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Fukushima Nuclear Accident Update Log

Full Update

IAEA Incident Emergency Centre (IEC)

Important Note on Updates


IAEA Briefing on Fukushima Nuclear Accident (2 June 2011, 18:30 UTC)


Presentations:
Summary of Reactor Status
Fukushima Radiological Monitoring and Consequences
Fukushima Marine Environment Monitoring
Watch Video

On Thursday, 2 June 2011, the IAEA provided the following information on the status of nuclear safety in Japan:

Overall, the situation at the Fukushima Daiichi nuclear power plant remains very serious.

The IAEA receives information from various official sources in Japan through the Japanese national competent authority, the Nuclear and Industrial Safety Agency (NISA). This Update Brief is based on information issued by the IAEA Incident and Emergency Centre up to 16:00 UTC on 31 May 2011.

1. Fukushima Daiichi Nuclear Power Plant Status

Tables 1 - 4 track progress for Units 1 - 4 towards fulfilling the three basic safety functions of the IAEA safety standards: prevention of criticality, removal of decay heat and mitigation of radioactive releases. The tables replace the three-colour table that was used previously. The charts are cross-referenced to the Tokyo Electric Power Company (TEPCO) "Roadmap" plan to bring the nuclear reactors and the spent fuel pools at the Fukushima Daiichi plant to a stable cooling condition and to mitigate radioactive releases.

On 17 May 2011, TEPCO provided a status report against the TEPCO "Roadmap" showing progress since the Roadmap was issued on 17 April 2011. While the basic policy and targets defined in the Roadmap remain, several changes were made to account for new information obtained and progress made to date.

On 13 May TEPCO commenced the preparatory work for the installation of a cover for the reactor building of Unit 1. The reactor building cover will be installed as an emergency measure to prevent the dispersion of radioactive substances until mid- to long term measures, including radiation shielding, are implemented.

TEPCO has reported that information obtained after calibration of the reactor water level gauges of Unit 1 shows that the actual water level in the Unit 1 reactor pressure vessel was lower than was indicated, showing that the fuel was completely uncovered. The results of provisional analysis show that fuel pellets melted and fell to the bottom of reactor pressure vessel at a relatively early stage in the accident.

TEPCO reported that "most part of the fuel is considered to be submerged in the bottom of reactor pressure vessel and some part exposed." TEPCO also reported that leakage of cooling water from the reactor pressure vessel is likely to have occurred. However, TEPCO considers that the actual damage to the reactor pressure vessel is limited, on the basis of the temperatures now being measured around the reactor pressure vessel.

The results of the analysis are provisional; TEPCO will continue to conduct investigations. Similar analyses will be conducted for Units 2 and 3 when radiation levels allow calibration of the instrumentation.

Nitrogen gas is still being injected into the containment vessel in Unit 1 to reduce the possibility of hydrogen combustion inside the containment vessel.

In Units 1, 2 and 3 fresh water is being continuously injected both via the feed water system lines and the fire extinguishers lines into the reactor pressure vessel; temperatures and pressures remain stable.

To protect against potential damage as a result of future earthquakes, TEPCO started work on 9 May to install a supporting structure for the floor of the spent fuel pool of Unit 4. TEPCO has formulated the hypothesis that the damage to the Unit 4 building could have been caused by hydrogen generated at Unit 3 that flowed into Unit 4.

Fresh water is being injected as necessary into the spent fuel pools of Units 1 - 4. Water supply from concrete pump trucks is being gradually replaced by the Fuel Pool Cooling and Clean-up system in Units 1 to 3. However, closed loop cooling has not been yet established.

Stagnant water with high levels of radioactivity in the basement of the turbine buildings of Units 1 and 3 is being transferred to the condensers, the radioactive waste treatment facility, the high-temperature incinerator building and temporary storage tanks. Stagnant water in the basement of the turbine building of Unit 6 is being transferred to a temporary tank. Countermeasures against the outflow of water to the sea and to prevent and minimize the dispersion of radionuclides in water have been put in place.

Full-scale spraying of anti-scattering agent is continuing at the site with the use of both conventional and remote controlled equipment.

2. Radiation Monitoring

The daily monitoring of the deposition of caesium and iodine radionuclides for 47 prefectures is continuing. Since 17 May, deposition of I-131 has not been observed. Low levels of Cs-137 deposition were reported in a few prefectures on a few days since 18 May; the reported values range of from 2.2 to 91 Bq/ m2 for Cs-137.

Gamma dose rates values for all 47 prefectures are reported daily by the Ministry of Education, Culture, Sports, Science and Technology (MEXT) of Japan. On 31 May the gamma dose rate reported for Fukushima prefecture was 1.5 µSv/h. In all other prefectures, reported gamma dose rates were below 0.1 µSv/h; with a general decreasing trend. Meanwhile, the decrease of the gamma dose rate has slowed down, since the short-lived radionuclides have decayed away.

Gamma dose rates reported specifically for the monitoring points in the eastern part of Fukushima prefecture, for distances of more than 30 km from the Fukushima Daiichi plant, showed a general decreasing trend, ranging from 0.1 µSv/h to 17 µSv/h, as reported for 31 May.

On-site measurements at the west gate of the Fukushima Daiichi plant indicate the presence of I-131 and Cs-137 in the air in the close vicinity of the plant (within approximately 1 km). The concentrations in air reported for 29 May were about 3 Bq/m3 for I-131 and about 9 Bq/m3 for Cs-137. The values observed in the previous days show daily fluctuations with an overall decreasing tendency.

Protective Actions

In April, the Government of Japan announced protective actions to reduce the external exposure to the population beyond a distance of 30 km from the Fukushima-Daiichi Nuclear Plant. NISA has reported that the evacuation of the "Planned Evacuation Zones" within Iitate village and Kawamata town commenced on 15 May. Confirmation of completion of the evacuation is awaited.

Food Monitoring and Food Restrictions

Food Monitoring (Reported from 19 to 31 May)

Food monitoring data were reported from 19 to 31 May by the Ministry of Health, Labour and Welfare for a total of 818 samples collected in 18 different prefectures. Most of the monitoring continues to be concentrated in Fukushima prefecture, where 328 out of the 818 samples (over 40%) were collected.

Analytical results for 766 samples (over 93%) of the 818 samples indicated that Cs-134 and Cs-137 or I-131 were either not detected or were below the regulation values set by the Japanese authorities. However, 52 samples were above the regulation values for radioactive caesium and/or iodine.

In Fukushima prefecture, five samples of fishery products collected on 16 and 17 May; one sample of unprocessed tea leaves collected on 17 May; three samples of shiitake mushrooms and nine samples of bamboo shoots collected on 19 May; five samples of seafood collected on 20, 21 and 23 May, and; one sample of Japanese apricot, two samples of shiitake mushrooms and seven samples of bamboo shoots collected on 26 May were above the regulation values for Cs-134/Cs-137. One sample of algae collected on 21 May was also above the regulation values for Cs-134/Cs-137 and I-131.

In Chiba, Gunma, Ibaraki and Tochigi prefectures, eighteen samples of unprocessed raw tea leaves collected on 17, 19, 24 and 26 May were above the regulation values for Cs-134/Cs-137.

Food Restrictions

Consolidated and updated information on food restrictions in Fukushima prefecture were reported on 30 May by the Ministry of Health Labour and Welfare indicating that restrictions on the distribution of bamboo shoots were lifted in the Hirata-Mura area. However, restrictions remain in effect on the distribution of raw unprocessed milk, turnips, bamboo shoots and ostrich fern in specific areas of the prefecture. Restrictions on the distribution and consumption of sand lance fish (the whole prefecture) and specific non-head type (e.g. spinach) and head-type leafy vegetables (e.g. cabbage), flower head brassicas (e.g. broccoli, cauliflower) and shiitake mushrooms (specific areas of the prefecture) also remain in effect.

In Ibaraki prefecture there is a continuing restriction on the distribution of spinach produced in the cities of Kitaibaraki and Takahagi.

3. Marine Monitoring

The marine monitoring programme is carried out both near the discharge areas of the Fukushima Daiichi plant by TEPCO at 22 locations and at off-shore stations by MEXT on 16 stations. The radioactive contamination of the marine environment had occurred by aerial deposition and by continuing discharges and outflow of water with various level of radioactivity from the four damaged reactors at Fukushima Daiichi.

Seawater Monitoring

The activity concentrations of I-131, Cs-134 and Cs-137 in seawater close to the Fukushima Daiichi plant at the screen of Unit 2 have been measured every day since 2 April. Concentrations of Cs-134 and Cs-137 decreased from of more than 100 MBq/L initially to less than 5 kBq/L on 7 May but increased again to levels of around 20 kBq/L at the 16 May and to about 10 kBq/L on the 17 May. Since then the concentrations dropped slowly to less than 2 kBq/L but increased to about 5 kBq/L on 29 May. The levels of I-131 are varying significantly and the activity ratio to radio-caesium is not constant. On 28 and 29 May the concentrations were around 20 kBq/L. The variability of I-131 relatively to the radio-caesium concentrations could be an indication of retention of caesium by the zeolite sandbags in place, which would have almost no effect on iodine or further production of decay products in the reactor.

Monitoring of the marine environment is performed by TEPCO on the near field area and by MEXT at off-shore sampling positions. The monitoring of MEXT includes also measurement of ambient dose rate in air above the sea, analysis of ambient dust above the sea, analysis of surface samples of sea water and analysis of samples of sea water collected at 10 m above the sea bottom and in a mid-layer as well at a few locations for sediments. On most of the offshore stations I-131, Cs-134 and Cs-137 reached levels below the applied detection limit of 10 Bq/L. There will be a further decrease of the concentration during the propagation of contaminated waters in the sea. The activity found in surface sediments at the near shore stations close to the reactors was between 24 and 320 Bq/kg for Cs-137 in the middle of May. The activity in sediments decreases with distance, but is also highly dependent upon the sediment type. The contamination of marine sediments indicates the enrichment of radio-caesium on particulate matter and its removal from the water column into the sea floor.

4. IAEA Activities

The Fact Finding Mission to Japan has now concluded the first part of its work and is on its way back to Vienna. The next part of the work will be to finalize and agree on the report, which will be presented at the Ministerial Conference in June. A preliminary summary is available on the IAEA website.


IAEA Briefing on Fukushima Nuclear Accident (12 - 18 May 2011, 17:00 UTC)


Presentations:
Summary of Reactor Status: Unit 1, 18 May 2011
Summary of Reactor Status: Unit 2, 18 May 2011
Summary of Reactor Status: Unit 3, 18 May 2011
Summary of Reactor Status: Unit 4, 18 May 2011

On Friday, 20 May 2011, the IAEA provided the following information on the status of nuclear safety in Japan:

1. Fukushima Daiichi Nuclear Power Plant Status

Tables 1 - 4 track progress made for each of Units 1 - 4 towards fulfilling the three basic safety functions of the IAEA safety standards: prevention of criticality, removal of decay heat and mitigation of radioactive releases. The tables replace the three-colour table that was used previously. The charts are cross-referenced to the Tokyo Electric Power Company (TEPCO) "Roadmap" plan to bring the nuclear reactors and the spent fuel pools at the Fukushima Daiichi plant to a stable cooling condition and to mitigate radioactive releases.

On 17 May 2011, TEPCO provided a status report against the TEPCO "Roadmap". Progress has been made during the last month since the issuing of the Roadmap on 17 April 2011. While the basic policy and targets defined in the Roadmap remain, several changes were made to account for new information obtained and progress made to date.

On 13 May TEPCO commenced the preparatory work for the installation of a cover for the reactor building of Unit 1. The reactor building cover will be installed as an emergency measure to prevent the dispersion of radioactive substances until mid- to long term measures, including radiation shielding, are implemented.

TEPCO has reported that information obtained after calibration of the reactor water level gauges of Unit 1 shows that the actual water level in the Unit 1 reactor pressure vessel was lower than was indicated, showing that the fuel was completely uncovered. The results of provisional analysis show that fuel pellets melted and fell to the bottom of reactor pressure vessel at a relatively early stage in the accident.

TEPCO reported that "most part of the fuel is considered to be submerged in the bottom of reactor pressure vessel and some part exposed." TEPCO also reported that leakage of cooling water from the reactor pressure vessel is likely to have occurred. However, TEPCO considers that the actual damage to the reactor pressure vessel is limited, on the basis of the temperatures now being measured around the reactor pressure vessel.

With regard to the status of the reactor core of Unit 1, TEPCO believes that because the fuel has been being cooled continuously by means of water injection, it is unlikely that the situation could result in a future release of large amounts of radioactive material.

The results of the analysis are provisional; TEPCO will continue to conduct investigations. Similar analyses will be conducted for Units 2 and 3.

Nitrogen gas is still being injected into the containment vessel in Unit 1 to reduce the possibility of hydrogen combustion inside the containment vessel.

In Units 1, 2 and 3 fresh water is being continuously injected into the reactor pressure vessel; temperatures and pressures remain stable.

To protect against potential damage as a result of future earthquakes, TEPCO started work on 9 May to install a supporting structure for the floor of the spent fuel pool of Unit 4.

Fresh water is being injected as necessary into the spent fuel pools of Units 1 - 4.

Stagnant water with high levels of radioactivity in the basement of the turbine buildings of Units 1, 2 and 3 is being transferred to the condensers, the radioactive waste treatment facility, the high-temperature incinerator building and temporary storage tanks. Stagnant water in the basement of the turbine building of Unit 6 is being transferred to a temporary tank. Countermeasures against the outflow of water to the sea and to prevent and minimize the dispersion of radionuclides in water have been put in place.

Full-scale spraying of anti-scattering agent is continuing at the site with the use of both conventional and remote controlled equipment.

2. Radiation Monitoring

Deposition in 47 Prefectures

The daily monitoring of the deposition of caesium and iodine radionuclides for 47 prefectures is continuing. Since 12 May negligible deposition has occurred. I-131 was reported in only one prefecture and Cs-137 was reported in three prefectures, with a value of 4.8 Bq/m2 for I-131 and a range of from 4.7 to 10 Bq/m2 for Cs-137.

Gamma Dose Rates in 47 Prefectures

Gamma dose rates are measured daily in all 47 prefectures. The Ministry of Education, Culture, Sports, Science and Technology (MEXT) of Japan reports values on the basis of data collected from each prefecture. On 18 May the value of gamma dose rate reported for Fukushima prefecture was 1.6 µSv/h. In all other prefectures, reported gamma dose rates were below 0.1 µSv/h, with a general decreasing trend.

Gamma Dose Rates in Areas More Than 30 km from Fukushima Daiichi Plant

Gamma dose rates reported specifically for the monitoring points in the eastern part of Fukushima prefecture, for distances of more than 30 km from the Fukushima Daiichi plant, showed a general decreasing trend, ranging from 0.1 µSv/h to 17 µSv/h, as reported for 17 May.

Maps of gamma dose rates, deposition of Cs-134 and deposition of Cs-137 within the 80 km zone around the Fukushima Daiichi plant were produced by means of aerial gamma ray monitoring by the Nuclear Safety Technology Centre of MEXT and the United States Department of Energy.

The map of the deposition of radiocaesium is presented in Fig. 1. The values represent the sum of Cs-134 and Cs-137. The areas in green show a deposition of these two radionuclides of between 0.6 and 1 MBq/m2. The areas in yellow indicate a deposition of between 1 and 3 MBq/m2. The areas in red indicate a deposition of between 3 and 30 MBq/m2. All are normalized to 29 April 2011.

The map shows that the results obtained are consistent with all previous reported measurements of deposition in soil and of gamma dose rates.

Air Concentrations of Radionuclides On-site at Fukushima Daiichi Plant

On-site measurements at the west gate of the Fukushima Daiichi plant indicate the presence of I-131 and Cs-137 in the air in the close vicinity of the plant (within approximately 1 km). The values observed in the previous days show daily fluctuations with an overall decreasing tendency.

Concentrations of Radionuclides in Drinking Water

As of 10 May, the restriction on the consumption of drinking water relating to I-131 - which had been applied since 1 April as a precautionary measure for one remaining location (the village of Iitate in Fukushima prefecture), and only for infants - was lifted.

Food Monitoring and Food Restrictions (12 - 18 May 2011)

Food Monitoring

From 12 to 18 May, the Ministry of Health, Labour and Welfare reported results of continued monitoring for radioactivity in food. Over this period, results for 503 food samples from fifteen different prefectures were reported. Most of this monitoring continues to be concentrated within Fukushima prefecture (39% of samples reported for 12 - 18 May). The majority of results were below regulation values, but 28 out of these 503 samples (fewer than 6%) were found to have radioactivity levels above the Japanese regulation values for radiocaesium. These samples were collected in three prefectures (Fukushima, Ibaraki and Kanagawa). None of the 503 samples was found to have radioiodine in excess of the regulation values.

In Fukushima prefecture, 175 of the 194 samples (more than 90%) had radiocaesium levels below the regulation values set by the Japanese authorities. However, 19 of the 194 samples (fewer than 10%) exceeded the regulation values for Cs-134/Cs-137. Samples above the regulation values were bamboo shoots (ten samples), shiitake mushrooms (five samples), and four samples of fish (two samples of whitebait, one sample of ayu and one sample of Japanese smelt).

In Kanagawa prefecture, 6 out of 33 samples (18%) were found to exceed the regulation values set by the Japanese authorities for Cs-134/Cs-137, these were six samples of unprocessed tea leaves (an additional ten samples of unprocessed tea leaves were found to have levels below this regulation value).

In Ibaraki prefecture, 3 of the 66 samples (4%) reported were above the regulation values set by the Japanese authorities for Cs-134/Cs-137. These were unprocessed tea leaves (two samples) and parsley (one sample).

Food Restrictions

As of 18 May, the only food restrictions remaining are in Fukushima prefecture and for the cities of Kitaibaraki and Takahagi in Ibaraki prefecture.

In Fukushima prefecture there are restrictions on the distribution and consumption of sand lance fish. In specified areas of Fukushima prefecture there are also restrictions on the distribution of raw unprocessed milk, turnips, bamboo shoots, ostrich ferns and shiitake mushrooms, and restrictions on the distribution and consumption of specific non-head type and head-type vegetables (e.g. spinach and cabbage), flowerhead brassicas (e.g. cauliflower) and shiitake mushrooms.

In Ibaraki prefecture there is a continuing restriction on the distribution of spinach produced in the cities of Kitaibaraki and Takahagi.

3. Marine Monitoring

The marine monitoring programme is carried out both near the discharge areas of the Fukushima Daiichi plant by TEPCO and at off-shore stations by MEXT. The increase in the radioactivity in the marine environment had occurred by aerial deposition and by continuing discharges and outflow of water with high levels of radioactivity from the Daiichi plant.

Seawater Monitoring

The activity concentrations of I-131, Cs-134 and Cs-137 in seawater close to the Fukushima Daiichi plant at the screen of Unit 2 have been measured every day since 2 April. Concentrations of Cs-134 and Cs-137 decreased from initial values of more than 100 MBq/L to less than 5 kBq/L on 7 May, but increased to levels of around 20 kBq/L on 16 May, and to about 10 kBq/L on 17 May. There was a significant increase in levels of I-131 from about 8 to 80 kBq/L from 10 to 11 May, in parallel with the increase for both radiocaesium isotopes. This indicates that there is still some production of fission products. The I-131 levels decreased to about 20 kBq/L on 17 May.

Monitoring of the marine environment is performed by TEPCO in the near field area and by MEXT at off-shore sampling positions. The monitoring of MEXT also includes: measurement of ambient dose rates in air above the sea; analysis of ambient dust above the sea; analysis of surface samples of sea water; and analysis of samples of sea water collected at 10 m above the sea bottom and in a mid-layer, as well as at several locations for sediments. At most of the offshore stations, I-131, Cs-134 and Cs-137 reached levels below the detection limit of 10 Bq/L.

Fig. 1.: Map of deposition of radiocaesium (sum of Cs-134 and Cs-137) for the land area within 80 km of the Fukushima Daiichi plant, as reported by the Japanese authorities (MEXT):

Aerial Measuring Results

IAEA Briefing on Fukushima Nuclear Accident (4 - 11 May 2011, 17:00 UTC)


Presentations:
Summary of Reactor Status: Unit 1, 11 May 2011
Summary of Reactor Status: Unit 2, 11 May 2011
Summary of Reactor Status: Unit 3, 11 May 2011

On Friday, 13 May 2011, the IAEA provided the following information on the status of nuclear safety in Japan:

1. Emergency at Fukushima Daiichi Nuclear Power Plant

Overall, the situation at the Fukushima Daiichi nuclear power plant remains very serious.

The IAEA receives information from various official sources in Japan through the Japanese national competent authority, the Nuclear and Industrial Safety Agency (NISA). This Update Brief is based on information issued by the IAEA Incident and Emergency Centre up to 17:00 UTC on 11 May 2011.

Fukushima Daiichi Nuclear Power Plant Status

The three attached charts, one for each of the Units 1 - 3, track progress made towards fulfilling the three basic safety functions of the IAEA safety standards: prevention of criticality, removal of decay heat and mitigation of radioactive releases. The chart replaces the three-colour status chart that was used previously. The charts are cross-referenced to the Tokyo Electric Power Company (TEPCO) "Roadmap" plan to bring the nuclear reactors and the spent fuel pools at the Fukushima Daiichi plant to a stable cooling condition and to mitigate radioactive releases.

Nitrogen gas is still being injected into the containment vessel in Unit 1 to reduce the possibility of hydrogen combustion inside the containment vessel.

TEPCO has elaborated a measure to fill the primary containment vessel of Unit 1 with water up to a level above the reactor fuel rods. This measure is intended to provide stable cooling of the reactor and reactor pressure vessel. The planned steps are:

  1. Reduce radiation levels in the reactor building by installing a filtered air circulation system (completed), remove rubble, decontaminate and install shielding;
  2. Recalibrate existing reactor pressure vessel water level and pressure instruments and install additional reactor pressure vessel water level gauges to improve monitoring of conditions inside the reactor pressure vessel;
  3. Install primary and secondary closed-loop cooling systems;
  4. Flood the containment to provide a water supply for the primary system.

In Units 1, 2 and 3 fresh water is being continuously injected into the reactor pressure vessel; temperatures and pressures remain stable.

To protect against potential damage as a result of future earthquakes, TEPCO started work on 9 May to install a supporting structure for the floor of the spent fuel pool of Unit 4.

Fresh water is being injected as necessary into the spent fuel pools of Units 1 - 4.

Stagnant water with high-level radioactivity in the basement of the turbine buildings of Unit 1, Unit 2 and Unit 3 is being transferred to the condensers, the radioactive waste treatment facility and temporary storage tanks. Stagnant water in the basement of the turbine building of Unit 6 is being transferred to a temporary tank. Countermeasures against the outflow of water to the sea and to prevent and minimize the dispersion of radionuclides in water have been put in place.

Full-scale spraying of anti-scattering agent is continuing at the site with the use of both conventional and remote controlled equipment.

2. Radiation Monitoring

Deposition in 47 Prefectures

The daily monitoring of the deposition of caesium and iodine radionuclides for 47 prefectures is continuing. For the period 5 - 10 May, deposition of I-131 was detected in three prefectures, with values ranging from 1.5 Bq/m2 to 4.5 Bq/m2. Deposition of Cs-137 was detected in eight prefectures in the same period, the values reported ranging from 3 Bq/m2 to 44 Bq/m2. The reported values show that variable but low level deposition of radionuclides was still occurring in some prefectures.

Gamma Dose Rates in 47 Prefectures

Gamma dose rates are measured daily in all 47 prefectures. On 10 May the value of gamma dose rate reported for Fukushima prefecture was 1.7 µSv/h. In all other prefectures, reported gamma dose rates were below 0.1 µSv/h with a general decreasing trend.

Gamma Dose Rates in Areas More Than 30 km from Fukushima Daiichi Plant

Gamma dose rates reported specifically for the monitoring points in the eastern part of Fukushima prefecture, for distances of more than 30 km from the Fukushima Daiichi plant, showed a general decreasing trend, ranging from 0.1 µSv/h to 20.3 µSv/h, as reported for 10 May.

Maps of gamma dose rates, deposition of Cs-134 and deposition of Cs-137 within the 80 km zone around the Fukushima Daiichi plant were produced by means of aerial gamma ray monitoring by the Nuclear Safety Technology Centre of MEXT and the United States Department of Energy (DOE). The maps show that the results obtained are consistent with all previous measurements of deposition in soil and of dose rates.

Air Concentrations of Radionuclides On-site at Fukushima Daiichi Plant

On-site measurements at the west gate of the Fukushima Daiichi plant indicate the presence of I-131 and Cs-137 in the air in the close vicinity of the plant (within approximately 1 km). The concentrations in air reported for 10 May were 4 Bq/m3 for total I-131 and 16 Bq/m3 for total Cs-137. The values observed in the previous days show daily fluctuations with an overall decreasing tendency.

Concentrations of Radionuclides in Drinking Water

As of 10 May, the restriction on the consumption of drinking water relating to I-131 - which had been applied since 1 April as a precautionary measure for one remaining location (the village of Iitate in Fukushima prefecture), and only for infants - was lifted.

Food Monitoring and Food Restrictions

Food Monitoring

The Ministry of Health, Labour and Welfare reported on the radionuclide test results for 4 - 11 May for 436 food samples from 14 different prefectures. The prefectures of Chiba, Fukushima, Gunma, Ibaraki, Miyagi, Niigata and Tochigi accounted for more than 90% of the reported food analysis results, with most food monitoring concentrated in Fukushima prefecture (52% of samples analysed and reported until 11 May). In two prefectures (Fukushima and Kanagawa), 17 out of 436 (3.9%) samples were found to have radioactivity above the Japanese regulation values.

In Fukushima prefecture, levels in 212 (93%) of the 228 samples reported were below the regulation values for I-131 and radioactive caesium. However, 16 of the 228 samples (7%) exceeded the regulation values set by the Japanese authorities for Cs-134/Cs-137, including bamboo shoots (eight samples), shiitake mushrooms (four samples), ostrich fern (two samples), turnip (one sample) and sand lance fish (one sample).

In Kanagawa prefecture, unprocessed tea leaves were the only food that exceeded the regulation values set by the Japanese authorities for Cs-134/Cs-137 (one of thirteen samples, i.e. 7.7%).

Food Restrictions

As of 11 May, the only food restrictions remaining are in Fukushima prefecture and for the cities of Kitaibaraki and Takahagi in Ibaraki prefecture.

In Fukushima prefecture there are restrictions on the distribution and consumption of sand lance fish. In specified areas of Fukushima prefecture there are also restrictions on the distribution of raw unprocessed milk, turnips, bamboo shoots, ostrich ferns and shiitake mushrooms, and restrictions on the distribution and consumption of specific non-head type and head-type vegetables (e.g. spinach and cabbage), flowerhead brassicas (e.g. cauliflower) and shiitake mushrooms.

In Ibaraki prefecture there is a continuing restriction on the distribution of spinach produced in the cities of Kitaibaraki and Takahagi.

3. Marine Monitoring

The marine monitoring programme is carried out both near the discharge areas of the Fukushima Daiichi plant by TEPCO and at off-shore stations by MEXT. The increase in the radioactivity in the marine environment had occurred by aerial deposition and by discharges and outflow of water with high level radioactivity.

Seawater Monitoring

The activity concentrations of I-131, Cs-134 and Cs-137 in seawater close to the Fukushima Daiichi plant at the screen of Unit 2 have been measured every day since 2 April. Concentrations of Cs-134 and Cs-137 decreased from initial values of more than 100 MBq/L to less than 10 kBq/L on 30 April and have remained constant at this level to the present.

Levels of I-131 on 7 May remained at around 200 Bq/L.

As of 7 May, no relevant changes in the radionuclides concentrations at the other TEPCO sampling positions have been reported.

Monitoring performed by MEXT at off-shore sampling positions consists of:

  1. Measurement of ambient dose rate in air above the sea;
  2. Analysis of ambient dust above the sea;
  3. Analysis of surface samples of seawater;
  4. Analysis of samples of seawater collected at 10 m above the sea bottom and in a mid-layer.

On 7 May the data reported only for the sampling points S1, S3 and 9 showed that Cs-137, Cs-134 and I-131 are not detectable.

4. Monitoring Data from IAEA Member States

Over the past ten weeks, the following States have provided the IAEA with monitoring data and/or links to their web sites: Algeria, Austria, Belgium, Bulgaria, Canada, China, Czech Republic, Denmark, Finland, France, Georgia, Germany, Greece, Iceland, Islamic Republic of Iran, Ireland, Italy, Republic of Korea, Latvia, Lithuania, Luxembourg, Malaysia, Mexico, Philippines, Poland, Portugal, Romania, Russian Federation, Singapore, Slovakia, Spain, Sri Lanka, Sweden, Switzerland, Ukraine and United States of America.

IAEA Briefing on Fukushima Nuclear Accident (5 May 2011, 20:00 UTC)


Presentations:
Summary of Reactor Status
Fukushima Radiological Monitoring and Consequences
Fukushima Marine Environment Monitoring
Watch Video

On Thursday, 5 May 2011, the IAEA provided the following information on the current status of nuclear safety in Japan:

1. Emergency at Fukushima Daiichi Nuclear Power Plant Since 21 April

Overall, the situation at the Fukushima Daiichi nuclear power plant remains very serious.

The IAEA receives information from various official sources in Japan through the Japanese national competent authority, the Nuclear and Industrial Safety Agency (NISA). This Update Brief is based on information received by the IAEA Incident and Emergency Centre up to 17:00 UTC on 3 May 2011.

Fukushima Daiichi Nuclear Power Plant Status

The IAEA has developed new charts for tracking the progress made towards fulfilling the three basic safety functions of the IAEA safety standards: prevention of criticality, removal of decay heat and mitigation of radioactive releases. These new charts, one for each of the reactor units and for the spent fuel pools, will replace the three-colour status chart that has been in use up until now. The charts provide the IAEA with a benchmark for following progress under "Roadmap" plan announced previously by the Tokyo Electric Power Company (TEPCO) to bring the nuclear reactors and the spent fuel pools at the Fukushima Daiichi plant to a stable ccooling condition and to mitigate radioactive releases.

On 27 April TEPCO provided an update of the estimated percentage of core damage for Units 1, 2 and 3: for Unit 1 the core damage was revised from an estimated 70% to 55%; for Unit 2 the core damage was revised from an estimated 30% to 35%; and for Unit 3 the core damage was revised from an estimated 25% to 30%. This reflects a revised assessment since 15 March rather than any recent changes in conditions in the reactor cores.

On 29 April TEPCO checked the status inside the reactor building of Unit 1 using a remotely controlled robot and confirmed that there was no significant leakage of water from the primary containment vessel. Nitrogen gas is still being injected into the containment vessel in Unit 1 to reduce the possibility of hydrogen combustion inside the containment vessel.

TEPCO has a plan to fill the primary containment vessel of Unit 1 with water up to a level above the reactor fuel rods. This measure is intended to provide stable cooling of the reactor and reactor pressure vessel. (On 5 May TEPCO submitted a report to NISA on this plan).

In Unit 2 and Unit 3 fresh water is being continuously injected into the reactor pressure vessel and temperatures and pressures remain stable.

Fresh water is being injected as necessary into the spent fuel pools of Units 1 - 4. Radionuclide analysis of a water sample taken from the Unit 4 spent fuel pool on 28 April detected levels of Cs-134 of 49 Bq/cm3; levels of Cs-137 of 55 Bq/cm3; and levels of I-131 of 27 Bq/cm3.

An amount of approximately 70 000 tonnes of stagnant water with high-level radioactivity in the basement of the turbine buildings of Unit 1, Unit 2 and Unit 3 is being transferred to the condensers, the radioactive waste treatment facility and temporary storage tanks. Stagnant water in the basement of the turbine building of Unit 6 is being transferred to a temporary tank. Countermeasures against water outflow to the sea and to prevent and minimize the spread of the radionuclides in water have been put in place.

Full-scale spraying of anti-scattering agent is continuing at the site with the use of both conventional and remote controlled equipment.

Measures Announced by Government of Japan

The Government of Japan announced the establishment or redesignation of the following zones:

  • A "no entry zone" within 20 km of the Fukushima Daiichi nuclear power plant (as of midnight, Japan local time, on 22 April 2011), with provision for temporary re-entry;
  • "Planned evacuation zones" to be applied to some specific zones outside the 20 km radius from the Fukushima Daiichi plant (from which planned evacuations were expected to be implemented in approximately one month's time from 22 April, so in late May);
  • "Emergency evacuation preparation zones" to be applied to the area within a 20 - 30 km radius from the Fukushima Daiichi plant (except for areas designated as planned evacuation zones), in which preparations should be made so that the residents can take shelter indoors or can evacuate the area by their own means in the event of an emergency.

The designation of "planned evacuation zones" applies to some specific zones outside the 20 km radius from the Fukushima Daiichi plant: "the villages of Katsurao, Namie and Iitate, part of the town of Kawamata, and part of the city of Minamisoma."

The designation of "emergency evacuation preparation zones" applies to the area within a 20 - 30 km radius from the Fukushima Daiichi plant (except for areas designated as planned evacuation zones): "the towns of Hirono and Naraha, the village of Kawauchi, and parts of the cities of Tamura and Minamisoma." In addition, with regard to the areas located within a 20 - 30 km radius from the nuclear power plant, the advisory for sheltering indoors that had been in effect to date was lifted.

With regard to the Fukushima Daini nuclear power plant, the Government of Japan also announced on April 21 that the size of the evacuation zone around the Fukushima Daini plant would be reduced from 10 km to 8 km and the order of evacuation would be lifted from areas farther than 8 km around the plant.

2. Radiation Monitoring (26 April to 3 May 2011)

Deposition in 47 Prefectures

The daily monitoring of the deposition of caesium and iodine radionuclides for 47 prefectures is continuing. For the period 22 April to 2 May, deposition of I-131 was detected in eight prefectures, ranging from 1.8 Bq/m2 to 89 Bq/m2. Deposition of Cs-137 was detected in 13 prefectures in the same period, the values reported ranging from 1.3 Bq/m2 to 92 Bq/m2. The reported values show that variable deposition of radionuclides was still occurring in certain prefectures. The values for deposition are significantly lower than those detected in the first weeks of the emergency and the number of prefectures affected is diminishing.

Gamma Dose Rates in 47 Prefectures

Gamma dose rates are measured daily in all 47 prefectures. The only notable values are those from Fukushima prefecture, where gamma dose rates were 1.8 µSv/h or just under, and Ibaraki prefecture, where gamma dose rates were 0.12 µSv/h or just under. In all other prefectures, reported gamma dose rates were below 0.1 µSv/h, with a general decreasing trend.

Gamma Dose Rates in Areas More Than 30 km from Fukushima Daiichi Plant

Gamma dose rates reported specifically for monitoring points in the eastern part of Fukushima prefecture, for distances of more than 30 km from the Fukushima Daiichi plant, showed a general decreasing trend over the period 26 April to 2 May, ranging from 0.1 µSv/h to 19.7 µSv/h.

Air Concentrations of Radionuclides On-site at Fukushima Daiichi Plant

On-site measurements at the west gate of the Fukushima Daiichi plant indicate the presence of I-131 and Cs-137 in the air in the close vicinity of the plant (within approximately 1 km). The concentrations in air reported for the period 31 March to 1 May ranged from 40 Bq/m3 to 1180 Bq/m3 for total I-131 and 10 Bq/m3 to 270 Bq/m3 for total Cs-137.

Concentrations of Radionuclides in Drinking Water

Since 1 April there has been one remaining restriction on the consumption of drinking water relating to I-131 (with a limit of 100 Bq/L), which is applicable only for the village of Iitate in the Fukushima prefecture and only for infants.

Both I-131 and Cs-137 are still detectable, but in only a few prefectures. According to the Japanese Ministry of Education, Culture, Sports, Science and Technology (MEXT), I-131 was detected in a maximum of six prefectures for the period 22 April to 1 May, with reported values ranging from 0.04 to 0.92 Bq/L; Cs-137 was reported in the same period in up to two prefectures with measured values ranging from 0.05 to 0.41 Bq/L. All these levels are below the limits set by the Japanese authorities for the restriction of water consumption due to the presence of radionuclides. The other samples did not show levels of radionuclides above the detection limit for I-131 and Cs-137.

Radiation Monitoring of Workers and Public

Radiation monitoring of workers and the public is continuing.

On 29 April, NISA reported that as of 27 April, 175 045 people had been monitored for radiation.

On 30 April TEPCO summarized the results of exposure measurements of workers engaged in emergency work whose external exposure exceeded 100 mSv at the end of March 2011. According to the summary, for total internal exposure and external exposure there were: two workers with effective doses of 200-250 mSv; eight workers with effective doses of 150-200 mSv; and 11 workers with effective doses of 100-150 mSv.

"Enforced Plan on Environmental Monitoring"

On 22 April MEXT issued a press release on an Enforced Plan on Environmental Monitoring that has the objectives of obtaining an overview and providing data necessary to support the decision to establish the planned evacuation zones.

To meet these objectives, the plan includes the following:

  • Collection of data on the distribution of radioactive material inside an appropriate area, including the area in the vicinity of the Fukushima Daiichi plant;
  • Preparation for future evaluations of changes in dose rates and accumulated amounts of radioactive substances in all delineated zones around the Fukushima Daiichi plant; and
  • Provision of information on environmental dose rates for the purpose of evaluation of personal radiation doses to local residents.

It was announced that maps will be produced on the basis of the results of environmental monitoring, including maps of dose rates and distributions of radioactivity, estimated accumulated doses and levels of soil surface contamination.

This Enforced Plan on Environmental Monitoring will be conducted in close cooperation between MEXT, Japan Atomic Energy Agency, universities, the Ministry of Defence, the police, prefectural police, Fukushima prefecture, electrical utilities and others, including the United States Department of Energy.

MEXT will compile all the data collected. MEXT and the Nuclear Safety Commission will cooperate with the Ministry of Economy, Trade and Industry (METI) and other organizations, and will establish procedures for standardizations on ranges and methods for the emergency environmental monitoring.

Food Monitoring and Food Restrictions (19 March to 3 May)

Food Monitoring

The Ministry of Health, Labour and Welfare reported that from 19 March to 3 May, 2 461 food samples had been collected from 18 different prefectures. The prefectures of Chiba, Fukushima, Gunma, Ibaraki, Niigata, Saitama and Tochigi accounted for more than 90% of the reported food analysis results, with most food monitoring concentrated in Fukushima prefecture (38% of samples analysed and reported until 3 May). In six prefectures (Chiba, Fukushima, Gunma, Ibaraki, Tochigi, Tokyo), 222 (9%) samples were found to have radioactivity above the Japanese regulation values.

In Fukushima prefecture, levels in over 84% of the 942 samples reported were below the regulation values for I-131 and radioactive caesium. However, 149 of 942 samples (16%) exceeded the regulation values, including vegetables (107 samples), shiitake mushrooms (19 samples), unprocessed raw milk (18 samples) and sand lance fish (five samples).

In Ibaraki prefecture, 89% of the 442 samples reported were below the regulation values. However, 47 of the 442 samples (11%) exceeded the regulation values, including vegetables (37 samples), unprocessed raw milk (five samples) and sand lance fish (five samples).

In four other prefectures, vegetables were the only foods that exceeded the regulation values (11 samples in Chiba, three samples in Gunma, 11 samples in Tochigi and one sample in Tokyo).

Food Restrictions

Restrictions on the distribution and/or consumption of milk and specific types of vegetables have been in place in five prefectures (Chiba, Fukushima, Gunma, Ibaraki and Tochigi) since they were first imposed on 21 March. As of 3 May, the only restrictions remaining are in Fukushima prefecture and for the cities of Kitaibaraki and Takahagi in Ibaraki prefecture.

Specifically, in Ibaraki prefecture there is a continuing restriction on the distribution of spinach produced in the cities of Kitaibaraki and Takahagi. In Fukushima prefecture there are restrictions on the distribution of turnips and on the distribution and consumption of sand lance fish and certain non-head type leafy vegetables (e.g. spinach). In specified areas of Fukushima prefecture there are also restrictions on the distribution of raw unprocessed milk and restrictions on the distribution and consumption of specific head-type vegetables (e.g. cabbage), flowerhead brassicas (e.g. cauliflower) and shiitake mushrooms.

3. Marine Monitoring

The marine monitoring programme is carried out both near the discharge areas of the Fukushima Daiichi plant by TEPCO and at off-shore stations by MEXT. The increase in the radioactivity in the marine environment had occurred by aerial deposition and by discharges and outflow of contaminated water with a high radioactivity level.

Seawater Monitoring

The activity concentrations of I-131, Cs-134 and Cs-137 in seawater close to the Daiichi plant at the screen of Unit 2 were measured every day from 2 April to 2 May. The concentrations fell by several orders of magnitude from initial values of more than 100 MBq/L at the beginning of April to less than 10 kBq/L for Cs-134 and Cs-137 on 30 April, with a continuing decreasing trend over time. The sandbags containing zeolite absorbers for absorbing caesium, which were placed at several locations between Unit 2 and Unit 4 to reduce concentrations of Cs-134 and Cs-137, do seem to have effected the observed reduction in the levels of caesium radionuclides. However, levels of I-131 remained at around 100 kBq/L from 26 April to 30 April; on 2 May they had increased to around 200 Bq/L at this sampling position.

The concentrations of the relevant radionuclides at the other TEPCO sampling positions show a general decreasing trend up to 4 May with some fluctuations.

Monitoring performed by MEXT at off-shore sampling positions consists of:

  1. Measurement of ambient dose rate in air above the sea;
  2. Analysis of ambient dust above the sea;
  3. Analysis of surface samples of seawater;
  4. Analysis of samples of seawater collected at 10 m above the sea bottom and in a mid-layer.

The analysis for almost all sampling positions has shown a general decreasing trend in concentrations of the relevant radionuclides over time. Samples were taken at stations 1 - 10 every four days after 2 April. Activity concentrations at MEXT sampling points 30 km off-shore are significantly lower than those at TEPCO sampling points 15 km off-shore due to further dilution. None of the activity concentrations of I-131 and Cs-137 in surface samples taken from points 1, 3, 5, 7, 9 and S-3 on 27 April and from points 2, 6 and S-4 on 25 April were above the detection limits. Samples taken from points 4, 8 and 10 showed concentrations of Cs-137 between of 10.5 Bq/L and 40 Bq/L. Only the sample from point 10 had an I-131 activity concentration, at 21.5 Bq/L, that was above the detection limit. (However, there was no information about the limit of detection.)

Samples were taken at the recently added off-shore stations at the Ibaraki prefecture on 25 April. There were no activity concentrations of I-131 and Cs-137 in the surface layer of sea water that were above the detection limits. MEXT has recently added an additional sampling point for sediment collection (S-4) near the Ibaraki coast.

Radiation Monitoring in Ports

On 22 April the Japanese Ministry of Land, Infrastructure, Transport and Tourism (MLIT) issued guidelines for radiation measurements in ports in Japan in order to provide foreign port authorities with accurate data. The guidelines cover gamma dose rate measurements for export shipping containers and shipping as well as radiation monitoring of the atmosphere and of sea water in ports.

Measurements relating to export shipping containers for export and to shipping can be conducted by the port authorities, by ship operators or by other parties.

The guidelines specify the measuring locations and methodology, as well as criteria for decontamination and for reporting. If measurements have been conducted in accordance with the guidelines, attestations of the measured dose rates will be issued jointly by MLIT and the port authorities.

With regard to export shipping containers, the guidelines state that decontamination is necessary if the measured dose rate exceeds three times the dose rate due to natural background radiation. Decontamination is to be carried out in an area to be specified by the port authorities. In accordance with the International Maritime Dangerous Goods code of the International Maritime Organization, a reporting level of 5 μSv/h is set. If the dose rate exceeds this reporting level, all relevant organizations are to be informed.

With regard to shipping, the guidelines recommend that decontamination should be carried out if the measured dose rate exceeds three times the dose rate due to natural background radiation, and decontamination must be carried out if the dose rate exceeds 5 μSv/h.

Radiation measurements in the atmosphere and in seawater in ports will be carried out by the port authorities or by MLIT.

4. IAEA Activities

Over the past eight weeks, the following States have provided the IAEA with monitoring data and/or links to their web sites: Austria, Belgium, Bulgaria, Canada, China, Czech Republic, Denmark, Finland, France, Georgia, Germany, Greece, Iceland, Islamic Republic of Iran, Ireland, Italy, Republic of Korea, Latvia, Lithuania, Luxembourg, Malaysia, Mexico, Philippines, Poland, Portugal, Romania, Russian Federation, Singapore, Slovakia, Spain, Sri Lanka, Sweden, Switzerland, Ukraine and United States of America. The IAEA Environmental Laboratories in Monaco also monitor air activity continuously for Monaco. Levels are in the same low range as elsewhere in Europe.

IAEA Briefing on Fukushima Nuclear Accident (5 May 2011, 20:00 UTC)


Presentations:
Summary of Reactor Status
Fukushima Radiological Monitoring and Consequences
Fukushima Marine Environment Monitoring
Watch Video

On Thursday, 5 May 2011, the IAEA provided the following information on the current status of nuclear safety in Japan:

1. Emergency at Fukushima Daiichi Nuclear Power Plant Since 21 April

Overall, the situation at the Fukushima Daiichi nuclear power plant remains very serious.

The IAEA receives information from various official sources in Japan through the Japanese national competent authority, the Nuclear and Industrial Safety Agency (NISA). This Update Brief is based on information received by the IAEA Incident and Emergency Centre up to 17:00 UTC on 3 May 2011.

Fukushima Daiichi Nuclear Power Plant Status

The IAEA has developed new charts for tracking the progress made towards fulfilling the three basic safety functions of the IAEA safety standards: prevention of criticality, removal of decay heat and mitigation of radioactive releases. These new charts, one for each of the reactor units and for the spent fuel pools, will replace the three-colour status chart that has been in use up until now. The charts provide the IAEA with a benchmark for following progress under "Roadmap" plan announced previously by the Tokyo Electric Power Company (TEPCO) to bring the nuclear reactors and the spent fuel pools at the Fukushima Daiichi plant to a stable ccooling condition and to mitigate radioactive releases.

On 27 April TEPCO provided an update of the estimated percentage of core damage for Units 1, 2 and 3: for Unit 1 the core damage was revised from an estimated 70% to 55%; for Unit 2 the core damage was revised from an estimated 30% to 35%; and for Unit 3 the core damage was revised from an estimated 25% to 30%. This reflects a revised assessment since 15 March rather than any recent changes in conditions in the reactor cores.

On 29 April TEPCO checked the status inside the reactor building of Unit 1 using a remotely controlled robot and confirmed that there was no significant leakage of water from the primary containment vessel. Nitrogen gas is still being injected into the containment vessel in Unit 1 to reduce the possibility of hydrogen combustion inside the containment vessel.

TEPCO has a plan to fill the primary containment vessel of Unit 1 with water up to a level above the reactor fuel rods. This measure is intended to provide stable cooling of the reactor and reactor pressure vessel. (On 5 May TEPCO submitted a report to NISA on this plan).

In Unit 2 and Unit 3 fresh water is being continuously injected into the reactor pressure vessel and temperatures and pressures remain stable.

Fresh water is being injected as necessary into the spent fuel pools of Units 1 - 4. Radionuclide analysis of a water sample taken from the Unit 4 spent fuel pool on 28 April detected levels of Cs-134 of 49 Bq/cm3; levels of Cs-137 of 55 Bq/cm3; and levels of I-131 of 27 Bq/cm3.

An amount of approximately 70 000 tonnes of stagnant water with high-level radioactivity in the basement of the turbine buildings of Unit 1, Unit 2 and Unit 3 is being transferred to the condensers, the radioactive waste treatment facility and temporary storage tanks. Stagnant water in the basement of the turbine building of Unit 6 is being transferred to a temporary tank. Countermeasures against water outflow to the sea and to prevent and minimize the spread of the radionuclides in water have been put in place.

Full-scale spraying of anti-scattering agent is continuing at the site with the use of both conventional and remote controlled equipment.

Measures Announced by Government of Japan

The Government of Japan announced the establishment or redesignation of the following zones:

  • A "no entry zone" within 20 km of the Fukushima Daiichi nuclear power plant (as of midnight, Japan local time, on 22 April 2011), with provision for temporary re-entry;
  • "Planned evacuation zones" to be applied to some specific zones outside the 20 km radius from the Fukushima Daiichi plant (from which planned evacuations were expected to be implemented in approximately one month's time from 22 April, so in late May);
  • "Emergency evacuation preparation zones" to be applied to the area within a 20 - 30 km radius from the Fukushima Daiichi plant (except for areas designated as planned evacuation zones), in which preparations should be made so that the residents can take shelter indoors or can evacuate the area by their own means in the event of an emergency.

The designation of "planned evacuation zones" applies to some specific zones outside the 20 km radius from the Fukushima Daiichi plant: "the villages of Katsurao, Namie and Iitate, part of the town of Kawamata, and part of the city of Minamisoma."

The designation of "emergency evacuation preparation zones" applies to the area within a 20 - 30 km radius from the Fukushima Daiichi plant (except for areas designated as planned evacuation zones): "the towns of Hirono and Naraha, the village of Kawauchi, and parts of the cities of Tamura and Minamisoma." In addition, with regard to the areas located within a 20 - 30 km radius from the nuclear power plant, the advisory for sheltering indoors that had been in effect to date was lifted.

With regard to the Fukushima Daini nuclear power plant, the Government of Japan also announced on April 21 that the size of the evacuation zone around the Fukushima Daini plant would be reduced from 10 km to 8 km and the order of evacuation would be lifted from areas farther than 8 km around the plant.

2. Radiation Monitoring (26 April to 3 May 2011)

Deposition in 47 Prefectures

The daily monitoring of the deposition of caesium and iodine radionuclides for 47 prefectures is continuing. For the period 22 April to 2 May, deposition of I-131 was detected in eight prefectures, ranging from 1.8 Bq/m2 to 89 Bq/m2. Deposition of Cs-137 was detected in 13 prefectures in the same period, the values reported ranging from 1.3 Bq/m2 to 92 Bq/m2. The reported values show that variable deposition of radionuclides was still occurring in certain prefectures. The values for deposition are significantly lower than those detected in the first weeks of the emergency and the number of prefectures affected is diminishing.

Gamma Dose Rates in 47 Prefectures

Gamma dose rates are measured daily in all 47 prefectures. The only notable values are those from Fukushima prefecture, where gamma dose rates were 1.8 µSv/h or just under, and Ibaraki prefecture, where gamma dose rates were 0.12 µSv/h or just under. In all other prefectures, reported gamma dose rates were below 0.1 µSv/h, with a general decreasing trend.

Gamma Dose Rates in Areas More Than 30 km from Fukushima Daiichi Plant

Gamma dose rates reported specifically for monitoring points in the eastern part of Fukushima prefecture, for distances of more than 30 km from the Fukushima Daiichi plant, showed a general decreasing trend over the period 26 April to 2 May, ranging from 0.1 µSv/h to 19.7 µSv/h.

Air Concentrations of Radionuclides On-site at Fukushima Daiichi Plant

On-site measurements at the west gate of the Fukushima Daiichi plant indicate the presence of I-131 and Cs-137 in the air in the close vicinity of the plant (within approximately 1 km). The concentrations in air reported for the period 31 March to 1 May ranged from 40 Bq/m3 to 1180 Bq/m3 for total I-131 and 10 Bq/m3 to 270 Bq/m3 for total Cs-137.

Concentrations of Radionuclides in Drinking Water

Since 1 April there has been one remaining restriction on the consumption of drinking water relating to I-131 (with a limit of 100 Bq/L), which is applicable only for the village of Iitate in the Fukushima prefecture and only for infants.

Both I-131 and Cs-137 are still detectable, but in only a few prefectures. According to the Japanese Ministry of Education, Culture, Sports, Science and Technology (MEXT), I-131 was detected in a maximum of six prefectures for the period 22 April to 1 May, with reported values ranging from 0.04 to 0.92 Bq/L; Cs-137 was reported in the same period in up to two prefectures with measured values ranging from 0.05 to 0.41 Bq/L. All these levels are below the limits set by the Japanese authorities for the restriction of water consumption due to the presence of radionuclides. The other samples did not show levels of radionuclides above the detection limit for I-131 and Cs-137.

Radiation Monitoring of Workers and Public

Radiation monitoring of workers and the public is continuing.

On 29 April, NISA reported that as of 27 April, 175 045 people had been monitored for radiation.

On 30 April TEPCO summarized the results of exposure measurements of workers engaged in emergency work whose external exposure exceeded 100 mSv at the end of March 2011. According to the summary, for total internal exposure and external exposure there were: two workers with effective doses of 200-250 mSv; eight workers with effective doses of 150-200 mSv; and 11 workers with effective doses of 100-150 mSv.

"Enforced Plan on Environmental Monitoring"

On 22 April MEXT issued a press release on an Enforced Plan on Environmental Monitoring that has the objectives of obtaining an overview and providing data necessary to support the decision to establish the planned evacuation zones.

To meet these objectives, the plan includes the following:

  • Collection of data on the distribution of radioactive material inside an appropriate area, including the area in the vicinity of the Fukushima Daiichi plant;
  • Preparation for future evaluations of changes in dose rates and accumulated amounts of radioactive substances in all delineated zones around the Fukushima Daiichi plant; and
  • Provision of information on environmental dose rates for the purpose of evaluation of personal radiation doses to local residents.

It was announced that maps will be produced on the basis of the results of environmental monitoring, including maps of dose rates and distributions of radioactivity, estimated accumulated doses and levels of soil surface contamination.

This Enforced Plan on Environmental Monitoring will be conducted in close cooperation between MEXT, Japan Atomic Energy Agency, universities, the Ministry of Defence, the police, prefectural police, Fukushima prefecture, electrical utilities and others, including the United States Department of Energy.

MEXT will compile all the data collected. MEXT and the Nuclear Safety Commission will cooperate with the Ministry of Economy, Trade and Industry (METI) and other organizations, and will establish procedures for standardizations on ranges and methods for the emergency environmental monitoring.

Food Monitoring and Food Restrictions (19 March to 3 May)

Food Monitoring

The Ministry of Health, Labour and Welfare reported that from 19 March to 3 May, 2 461 food samples had been collected from 18 different prefectures. The prefectures of Chiba, Fukushima, Gunma, Ibaraki, Niigata, Saitama and Tochigi accounted for more than 90% of the reported food analysis results, with most food monitoring concentrated in Fukushima prefecture (38% of samples analysed and reported until 3 May). In six prefectures (Chiba, Fukushima, Gunma, Ibaraki, Tochigi, Tokyo), 222 (9%) samples were found to have radioactivity above the Japanese regulation values.

In Fukushima prefecture, levels in over 84% of the 942 samples reported were below the regulation values for I-131 and radioactive caesium. However, 149 of 942 samples (16%) exceeded the regulation values, including vegetables (107 samples), shiitake mushrooms (19 samples), unprocessed raw milk (18 samples) and sand lance fish (five samples).

In Ibaraki prefecture, 89% of the 442 samples reported were below the regulation values. However, 47 of the 442 samples (11%) exceeded the regulation values, including vegetables (37 samples), unprocessed raw milk (five samples) and sand lance fish (five samples).

In four other prefectures, vegetables were the only foods that exceeded the regulation values (11 samples in Chiba, three samples in Gunma, 11 samples in Tochigi and one sample in Tokyo).

Food Restrictions

Restrictions on the distribution and/or consumption of milk and specific types of vegetables have been in place in five prefectures (Chiba, Fukushima, Gunma, Ibaraki and Tochigi) since they were first imposed on 21 March. As of 3 May, the only restrictions remaining are in Fukushima prefecture and for the cities of Kitaibaraki and Takahagi in Ibaraki prefecture.

Specifically, in Ibaraki prefecture there is a continuing restriction on the distribution of spinach produced in the cities of Kitaibaraki and Takahagi. In Fukushima prefecture there are restrictions on the distribution of turnips and on the distribution and consumption of sand lance fish and certain non-head type leafy vegetables (e.g. spinach). In specified areas of Fukushima prefecture there are also restrictions on the distribution of raw unprocessed milk and restrictions on the distribution and consumption of specific head-type vegetables (e.g. cabbage), flowerhead brassicas (e.g. cauliflower) and shiitake mushrooms.

3. Marine Monitoring

The marine monitoring programme is carried out both near the discharge areas of the Fukushima Daiichi plant by TEPCO and at off-shore stations by MEXT. The increase in the radioactivity in the marine environment had occurred by aerial deposition and by discharges and outflow of contaminated water with a high radioactivity level.

Seawater Monitoring

The activity concentrations of I-131, Cs-134 and Cs-137 in seawater close to the Daiichi plant at the screen of Unit 2 were measured every day from 2 April to 2 May. The concentrations fell by several orders of magnitude from initial values of more than 100 MBq/L at the beginning of April to less than 10 kBq/L for Cs-134 and Cs-137 on 30 April, with a continuing decreasing trend over time. The sandbags containing zeolite absorbers for absorbing caesium, which were placed at several locations between Unit 2 and Unit 4 to reduce concentrations of Cs-134 and Cs-137, do seem to have effected the observed reduction in the levels of caesium radionuclides. However, levels of I-131 remained at around 100 kBq/L from 26 April to 30 April; on 2 May they had increased to around 200 Bq/L at this sampling position.

The concentrations of the relevant radionuclides at the other TEPCO sampling positions show a general decreasing trend up to 4 May with some fluctuations.

Monitoring performed by MEXT at off-shore sampling positions consists of:

  1. Measurement of ambient dose rate in air above the sea;
  2. Analysis of ambient dust above the sea;
  3. Analysis of surface samples of seawater;
  4. Analysis of samples of seawater collected at 10 m above the sea bottom and in a mid-layer.

The analysis for almost all sampling positions has shown a general decreasing trend in concentrations of the relevant radionuclides over time. Samples were taken at stations 1 - 10 every four days after 2 April. Activity concentrations at MEXT sampling points 30 km off-shore are significantly lower than those at TEPCO sampling points 15 km off-shore due to further dilution. None of the activity concentrations of I-131 and Cs-137 in surface samples taken from points 1, 3, 5, 7, 9 and S-3 on 27 April and from points 2, 6 and S-4 on 25 April were above the detection limits. Samples taken from points 4, 8 and 10 showed concentrations of Cs-137 between of 10.5 Bq/L and 40 Bq/L. Only the sample from point 10 had an I-131 activity concentration, at 21.5 Bq/L, that was above the detection limit. (However, there was no information about the limit of detection.)

Samples were taken at the recently added off-shore stations at the Ibaraki prefecture on 25 April. There were no activity concentrations of I-131 and Cs-137 in the surface layer of sea water that were above the detection limits. MEXT has recently added an additional sampling point for sediment collection (S-4) near the Ibaraki coast.

Radiation Monitoring in Ports

On 22 April the Japanese Ministry of Land, Infrastructure, Transport and Tourism (MLIT) issued guidelines for radiation measurements in ports in Japan in order to provide foreign port authorities with accurate data. The guidelines cover gamma dose rate measurements for export shipping containers and shipping as well as radiation monitoring of the atmosphere and of sea water in ports.

Measurements relating to export shipping containers for export and to shipping can be conducted by the port authorities, by ship operators or by other parties.

The guidelines specify the measuring locations and methodology, as well as criteria for decontamination and for reporting. If measurements have been conducted in accordance with the guidelines, attestations of the measured dose rates will be issued jointly by MLIT and the port authorities.

With regard to export shipping containers, the guidelines state that decontamination is necessary if the measured dose rate exceeds three times the dose rate due to natural background radiation. Decontamination is to be carried out in an area to be specified by the port authorities. In accordance with the International Maritime Dangerous Goods code of the International Maritime Organization, a reporting level of 5 μSv/h is set. If the dose rate exceeds this reporting level, all relevant organizations are to be informed.

With regard to shipping, the guidelines recommend that decontamination should be carried out if the measured dose rate exceeds three times the dose rate due to natural background radiation, and decontamination must be carried out if the dose rate exceeds 5 μSv/h.

Radiation measurements in the atmosphere and in seawater in ports will be carried out by the port authorities or by MLIT.

4. IAEA Activities

Over the past eight weeks, the following States have provided the IAEA with monitoring data and/or links to their web sites: Austria, Belgium, Bulgaria, Canada, China, Czech Republic, Denmark, Finland, France, Georgia, Germany, Greece, Iceland, Islamic Republic of Iran, Ireland, Italy, Republic of Korea, Latvia, Lithuania, Luxembourg, Malaysia, Mexico, Philippines, Poland, Portugal, Romania, Russian Federation, Singapore, Slovakia, Spain, Sri Lanka, Sweden, Switzerland, Ukraine and United States of America. The IAEA Environmental Laboratories in Monaco also monitor air activity continuously for Monaco. Levels are in the same low range as elsewhere in Europe.

IAEA Briefing on Fukushima Nuclear Accident (3 May 2011, 19:50 UTC)


Presentation:
Summary of Reactor Status

On Tuesday, 3 May 2011, the IAEA provided the following information on the current status of nuclear safety in Japan:

1. Current Situation

Overall, the situation at the Fukushima Daiichi nuclear power plant remains very serious.

Changes to Fukushima Daiichi Nuclear Power Plant Status

The IAEA receives information from various official sources in Japan through the Japanese national competent authority, the Nuclear and Industrial Safety Agency (NISA). The Update Brief is based on information received by the IAEA Incident and Emergency Centre by 17:00 UTC on 2 May 2011.

Management of On-site Contaminated Water

According to the 25 April evaluation by NISA of the report submitted by the Tokyo Electric Power Company (TEPCO), there is a little less than 70 000 tonnes of stagnant water with high-level radioactivity in the basement of the turbine buildings of Units 1, 2 and 3.

The stagnant water (around 120 m3) in the basement of the turbine building of Unit 6 was transferred to a temporary tank on 1 May. The transfer of stagnant water from the basement of the turbine building of Unit 6 was resumed on 2 May.

Work to block the Unit 2 trench pit was started on 1 May.

Plant Status

On 27 April TEPCO provided an update of the estimated percentage of core damage for Units 1, 2 and 3 following an assessment (the values assessed previously which TEPCO had provided on 15 March are given in parentheses): Unit 1: 55% core damage (70%); Unit 2: 35% core damage (30%); Unit 3: 30% core damage (25%). This reflects a revised assessment rather than any recent changes in conditions in the reactor cores.

White "smoke" continues to be emitted from Unit 2 and Unit 3. There was no more white "smoke" seen emanating from Unit 4 as of 21:30 UTC on 25 April or from Unit 1 as of 21:30 UTC on 30 April.

In Unit 1 fresh water is being continuously injected into the reactor pressure vessel through the feedwater line at an indicated flow rate of 6 m3/h using a temporary electric pump with off-site power.

In Unit 2 and Unit 3 fresh water is being continuously injected into the reactor pressure vessel through the fire extinguisher line at an indicated rate of 7 m3/h using temporary electric pumps with off-site power.

On 29 April TEPCO checked the status inside the reactor building of Unit 1 using a remotely controlled robot and confirmed that there was no significant leakage of water from the primary containment vessel. Nitrogen gas is still being injected into the containment vessel in Unit 1 to reduce the possibility of hydrogen combustion inside the containment vessel. The indicated pressure in the reactor pressure vessel is still increasing.

In Unit 1, the indicated temperature at the feedwater nozzle of the reactor pressure vessel is 142 °C and at the bottom of reactor pressure vessel is 106 °C.

In Unit 2 the indicated temperature at the feedwater nozzle of the reactor pressure vessel is 118 °C. The reactor pressure vessel and the dry well remain at atmospheric pressure. On 28 April an amount of 43 tonnes of fresh water was injected into the spent fuel pool using the spent fuel pool clean-up system.

In Unit 3 the indicated temperature at the feed water nozzle of the reactor pressure vessel is 99 °C and at the bottom of the reactor pressure vessel is 124 °C. The reactor pressure vessel and the dry well remain at atmospheric pressure.

On 2 May an amount of 55 tonnes of fresh water was injected into the Unit 2 spent fuel pool using the fuel pool clean-up system.

There has been no change in the status in Unit 5 or in the common spent fuel storage facility.

Spraying of anti-scattering agent at the site is continuing. An area of about 1 000 m2 on the south side of the turbine building of Unit 4, and an area of about 4 400 m2 of the surface on the slope around the former main office building, near the on-site gymnasium and on the west side of the shallow draft quay, were sprayed on 1 May.

2. Radiation Monitoring

The daily monitoring of deposition of caesium and iodine radionuclides for the 47 prefectures continues. Deposition of Cs-137 and Cs-134 was detected in six prefectures on 2 May. The values reported ranged from 2.6 Bq/m2 to 19 Bq/m2. Compared with recent data, deposition of these radionuclides has been detected in fewer prefectures and in lower amounts than for previous days.

Gamma dose rates are measured daily in all 47 prefectures. A general decreasing trend has been observed in all locations since around 20 March. Gamma dose rates reported on 2 May remain at 1.7 µSv/h for Fukushima prefecture and 0.11 µSv/h for Ibaraki prefecture. The other 45 prefectures had gamma dose rates of below 0.1 µSv/h, falling within the range of local natural background radiation levels.

Gamma dose rates reported specifically for the eastern part of Fukushima prefecture, for distances of more than 30 km from the Fukushima Daiichi plant, ranged from 0.1 µSv/h to 19.7 µSv/h, as reported on 2 May.

Since 1 April there has been one remaining restriction on the consumption of drinking water relating to I-131 (with a limit of 100 Bq/L), which is applicable only for one village in the Fukushima prefecture and only for infants. According to the Japanese Ministry of Education, Culture, Sports, Science and Technology (MEXT), I-131 was detected in one prefecture on 29 April, with a reported value of 0.22 Bq/L; in two prefectures on 30 April, with reported levels of 0.04 Bq/L and 0.10 Bq/L respectively; and in one prefecture on 1 May, with a reported level of 0.38 Bq/L. Cs-137 was reported on 30 April in only one prefecture, with a measured level of 0.05 Bq/L. All these levels are below the limits set by the Japanese authorities for the restriction of water consumption due to the presence of radionuclides. The other samples did not show levels of radionuclides above the detection limit for I-131, Cs-134 and Cs-137.

Food Restrictions

On 1 May restrictions were lifted on the distribution of raw unprocessed milk in Fukushima prefecture from the city of Minamisouma (limited to Kashima-ku and excluding Karasuzaki, Ouchi, Kawago and Shionosaki areas) and Kawamata town (excluding Yamakiya area).

3. Marine Monitoring

The marine monitoring programme is carried out both near the discharge areas of the Fukushima Daiichi plant by TEPCO and at off-shore stations by MEXT. (The locations of the sampling positions have been provided in previous briefings.) Increased radioactivity in the marine environment occurred by aerial deposition and by discharges and outflow of contaminated water with a high radioactivity level.

Marine Discharges

In a news release issued on 25 April, NISA communicated its evaluation of a report submitted by TEPCO on 21 April in relation to contaminated water with a high radioactivity level that flowed out from Unit 2 of the Fukushima Daiichi plant. The outflow rate is estimated to have been approximately 4.3 m3/h. The concentrations of the relevant radionuclides, estimated from measurements, were 5400 MBq/L of I-131, 1800 MBq/L of Cs-134 and 1800 MBq/L of Cs-137.

Seawater Monitoring

The activity concentrations of I-131, Cs-134 and Cs-137 in sea water at the screen of Unit 2 were measured every day from 2 April to 30 April. The concentrations fell by several orders of magnitude from initial values of more than 100 MBq/L at the beginning of April to less than 10 kBq/L for Cs-134 and Cs-137 on 30 April, with a continuing decreasing trend. However, levels of I-131 remained at around 100 kBq/L from 26 April to 30 April at this sampling position. The sandbags containing Zeolite® absorbers that were placed at several locations between Unit 2 and Unit 4 to reduce the concentrations of Cs-134 and Cs-137 seem to be effective.

The concentrations of the relevant radionuclides at the other TEPCO sampling positions show a general decreasing trend up to 30 April.

Monitoring performed by MEXT at off-shore sampling positions consists of:

  • Measurement of ambient dose rate in air above the sea;
  • Analysis of ambient dust above the sea;
  • Analysis of surface samples of seawater; and
  • Analysis of samples of seawater collected at 10 m above the sea bottom.

The analysis for almost all sampling positions has shown a general decreasing trend in concentrations of the relevant radionuclides over time. Samples were taken at stations 1 - 10 every four days after 2 April. Activity concentrations at MEXT sampling points 30 km off-shore are significantly lower than those at TEPCO sampling points 15 km off-shore. None of the activity concentrations of I-131 and Cs-137 in surface samples taken from points 1, 3, 5, 7, 9 and S-3 on 27 April and from points 2, 6 and S-4 on 25 April were above the detection limits. Samples taken from points 4, 8 and 10 showed concentrations of Cs-137 between of 10.5 Bq/L and 40 Bq/L. Only the sample from point 10 had an I-131 activity concentration, at 21.5 Bq/L, that was above the detection limit.

Samples were taken at the recently added off-shore stations at the Ibaraki prefecture on 25 April. There were no activity concentrations of I-131 and Cs-137 in the surface layer of sea water that were above the detection limits.

Radiation Monitoring in Ports

On 22 April the Japanese Ministry of Land, Infrastructure, Transport and Tourism (MLIT) issued guidelines for radiation measurements in ports in Japan in order to provide foreign port authorities with accurate data. The guidelines cover gamma dose rate measurements for export shipping containers and shipping as well as radiation monitoring of the atmosphere and of sea water in ports.

Measurements relating to export shipping containers for export and to shipping can be conducted by the port authorities, by ship operators or by other parties. The guidelines specify the measuring locations and methodology, as well as criteria for decontamination and for reporting. If measurements have been conducted in accordance with the guidelines, attestations of the measured dose rates will be issued jointly by MLIT and the port authorities.

With regard to export shipping containers, the guidelines state that decontamination is necessary if the measured dose rate exceeds three times the dose rate due to natural background radiation. Decontamination is to be carried out in an area to be specified by the port authorities. In accordance with the International Maritime Dangerous Goods Code of the International Maritime Organization, a reporting level of 5 µSv/h is set. If the dose rate exceeds this reporting level, all relevant organizations are to be informed.

With regard to shipping, the guidelines recommend that decontamination should be carried out if the measured dose rate exceeds three times the dose rate due to natural background radiation, and decontamination must be carried out if the dose rate exceeds 5 µSv/h.

Radiation measurements in the atmosphere and in sea water in ports will be carried out by the port authorities or by MLIT.

IAEA Briefing on Fukushima Nuclear Accident (2 May 2011, 19:50 UTC)


Presentation:
Summary of Reactor Status

On Monday, 2 May 2011, the IAEA provided the following information on the current status of nuclear safety in Japan:

1. Current Situation

Overall, the situation at the Fukushima Daiichi nuclear power plant remains very serious.

Changes to Fukushima Daiichi Nuclear Power Plant Status

The IAEA receives information from various official sources in Japan through the Japanese national competent authority, the Nuclear and Industrial Safety Agency (NISA).

Management of On-site Contaminated Water

According to the 25 April evaluation by NISA of the report submitted by the Tokyo Electric Power Company (TEPCO), there is a little less than 70 000 tonnes of stagnant water with high-level radioactivity in the basement of the turbine buildings of Units 1, 2 and 3. The transfer of stagnant water from the turbine building of Unit 2 to the radioactive waste treatment facilities was resumed on 30 April.

Plant Status

On 27 April TEPCO provided an update of the estimated percentage of core damage for Units 1, 2 and 3 following an assessment (the values assessed previously which TEPCO had provided on 15 March are given in parentheses): Unit 1: 55% core damage (70%); Unit 2: 35% core damage (30%); Unit 3: 30% core damage (25%). This reflects a revised assessment rather than any recent changes in conditions in the reactor cores.

White &qout;smoke" continues to be emitted from Unit 2 and Unit 3. No more white &qout;smoke&qout; was seen coming from Unit 4 as of 21:30 UTC on 25 April or from Unit 1 as of 21:30 UTC on 30 April.

In Unit 1 fresh water is being continuously injected into the reactor pressure vessel through the feedwater line at an indicated flow rate of 6 m3/h using a temporary electric pump with off-site power.

In Unit 2 and Unit 3 fresh water is being continuously injected into the reactor pressure vessel through the fire extinguisher line at an indicated rate of 7 m3/h using temporary electric pumps with off-site power.

On 29 April, TEPCO checked the status inside the reactor building of Unit 1 using a remotely controlled robot and confirmed that there was no significant leakage of water from the primary containment vessel. Nitrogen gas is still being injected into the containment vessel in Unit 1 to reduce the possibility of hydrogen combustion inside the containment vessel. The indicated pressure in the reactor pressure vessel is still increasing.

In Unit 1, the indicated temperature at the feedwater nozzle of the reactor pressure vessel is 142 °C and at the bottom of reactor pressure vessel is 105 °C.

In Unit 2 the indicated temperature at the feedwater nozzle of the reactor pressure vessel is 119 °C. The reactor pressure vessel and the dry well remain at atmospheric pressure. On 28 April an amount of 43 tonnes of fresh water was injected into the spent fuel pool using the spent fuel pool clean-up system.

In Unit 3 the indicated temperature at the feed water nozzle of the reactor pressure vessel is 91 °C and at the bottom of the reactor pressure vessel is 118 °C. The reactor pressure vessel and the dry well remain at atmospheric pressure.

Radionuclide analysis of a water sample taken from the Unit 4 spent fuel pool on 28 April detected levels of Cs-134of 49 Bq/cm3; levels of Cs-137 of 55 Bq/cm3; and levels of I-131 of 27 Bq/cm3.

There has been no change in the status in Unit 5 or Unit 6 or in the common spent fuel storage facility.

Spraying of anti-scattering agent at the site is continuing. An area of about 2 000 m2 on the south side of the turbine building of Unit 4, and an area of about 5 400 m2 of the surface on the slope around the former main office building, near the on-site gymnasium and on the west side of the shallow draft quay, were sprayed on 30 April.

2. Radiation Monitoring

Deposition of Cs-137 was detected in ten prefectures in the period 28 April to 1 May. The values reported ranged from 1.3 Bq/m2 to 90 Bq/m2. I-131 deposition was reported for two prefectures on 28 April and for one on 1 May, with values of 45 Bq/m2, 89 Bq/m2 and 1.8 Bq/m2.

Gamma dose rates are measured daily in all 47 prefectures. A general decreasing trend has been observed in all locations since around 20 March. For the Fukushima prefecture gamma dose rates were 1.7 µSv/h on 1 May. In Ibaraki prefecture gamma dose rates were 0.11 µSv/h. The other 45 prefectures had gamma dose rates of below 0.1 µSv/h, falling within the range of local natural background radiation levels.

Gamma dose rates reported specifically for the eastern part of Fukushima prefecture, for distances beyond 30 km from the Fukushima Daiichi plant, showed a similar general decreasing trend, ranging from 0.1 to 18.1 µSv/h, as reported on 30 April.

On-site measurements at the west gate of the Fukushima Daiichi plant indicate the presence of I-131 and Cs-137 in the air in the close vicinity of the plant (within approximately 1 km). The values reported for the period 27 April - 1 May ranged from 0.4x 10-4 Bq/cm3 to 2.2 x 10-4 Bq/cm3 for total I-131 and 0.1 x 10-4 Bq/cm3 to 0.3x 10-4 Bq/cm3 for particulate Cs-137.

Since 1 April there has been one remaining restriction on the consumption of drinking water relating to I-131 (with a limit of 100 Bq/L), which applies to one village in the Fukushima prefecture and only for infants. According to the Japanese Ministry of Education, Culture, Sports, Science and Technology (MEXT), only three samples of drinking water reported on 28 April from the 47 prefectures had levels above the detection limit for I-131. These three levels, which measured 0.14 Bq/L, 0.16 Bq/L and 0.54 Bq/L, were all below the regulation value set by the Japanese authorities. No samples were reported with levels above the detection limit for Cs-134 and Cs-137.

Food Monitoring

Food monitoring data were reported by the Japanese Ministry of Health, Labour and Welfare on 28, 29, 30 April and 1 May for a total of 190 samples taken on 25 - 30 April and 1 May from 12 prefectures (Chiba, Fukushima, Gunma, Hyogo, Ibaraki, Kanagawa, Nagano, Niigata, Saitama, Tochigi, Tokyo and Yamagata). Analytical results for 180 of the 190 samples for various vegetables, mushrooms, fruit (strawberries), beef, pork, poultry eggs, seafood, fresh milk, raw unprocessed milk and yoghurt indicated that I-131, Cs-134 and Cs-137 were either not detected or were below the regulation values set by the Japanese authorities. In Fukushima prefecture, one sample of bamboo shoot from 27 April and one sample of ostrich fern and five samples of shiitake mushrooms from 28 April were above the regulation values set by the Japanese authorities for Cs-134/Cs-137. In Ibaraki prefecture, three samples of seafood (sand lance) from 28 April (one sample) and 29 April (two samples) were above the regulation values set by the Japanese authorities for Cs-134/Cs-137.

3. Marine Monitoring

The marine monitoring programme is carried out both near the discharge areas of the Fukushima Daiichi plant by TEPCO and at off-shore stations by the Japanese Ministry of Education, Culture, Sports, Science and Technology (MEXT). The locations of the sampling positions were provided in previous briefings. Increased radioactivity in the marine environment occurred by aerial deposition and by discharges and outflow of contaminated water with a high radioactivity level.

Marine Discharges

In a news release issued on 25 April, NISA communicated its evaluation of a report submitted by TEPCO on 21 April in relation to contaminated water with a high radioactivity level that flowed out from Unit 2 of the Fukushima Daiichi plant. The outflow rate is estimated to have been approximately 4.3 m3/h. The concentrations of the relevant radionuclides, estimated from measurements, were 5400 MBq/L of I-131, 1800 MBq/L of Cs-134 and 1800 MBq/L of Cs-137.

Sea Water Monitoring

The activity concentrations of I-131, Cs-134 and Cs-137 in sea water at the screen of Unit 2 were measured every day from 2 April 2011 to 30 April 2011. The concentrations fell by several orders of magnitude from initial values of more than 100 MBq/L at the beginning of April to less than 10 kBq/L for Cs-134 and Cs-137 on 30 April, with a continuing decreasing trend. However, levels of I-131 remained at around 100 kBq/L from 26 April to 30 April at this sampling position.

The concentrations of the relevant radionuclides at the other TEPCO sampling positions show a general decreasing trend up to 30 April.

Monitoring at off-shore sampling positions consists of:

  • Measurement of ambient dose rate in air above the sea;
  • Analysis of ambient dust above the sea;
  • Analysis of surface samples of sea water; and
  • Analysis of samples of sea water collected at 10 m above the sea bottom.

The analysis for almost all sampling positions has shown a general decreasing trend in concentrations of the relevant radionuclides over time. Samples from coastal positions still show higher concentrations of such radionuclides than samples from off-shore positions. The radionuclides I-131, Cs-134 and Cs-137 are still detected in most sea water samples, but no longer for some of the off-shore positions.

IAEA Update Briefing on Fukushima Nuclear Accident (28 April 2011, 18:00 UTC)


Presentation:
Summary of Reactor Status

On Thursday, 28 April 2011, the IAEA provided the following information on the current status of nuclear safety in Japan:

1. Current Situation

Overall, the situation at the Fukushima Daiichi nuclear power plant remains very serious, but there are signs of recovery in some functions, such as electrical power and instrumentation.

Changes to Fukushima Daiichi Nuclear Power Plant Status

The IAEA receives information from various official sources in Japan through the Japanese national competent authority, the Nuclear and Industrial Safety Agency (NISA).

Management of On-site Contaminated Water

According to the 25 April evaluation by NISA of the report submitted by the Tokyo Electric Power Company (TEPCO), there is a little less than 70 000 tonnes of stagnant water with high-level radioactivity in the basement of the turbine buildings of Units 1, 2 and 3.

Plant Status

On 25 April the power supply for the temporary electrical pumps that supply water to the reactor pressure vessel of Units 1, 2 and 3 was switched from the off-site power supply to temporary diesel generators to allow work to enhance the off-site power supply. The power supply has now been returned to the off-site supply.

White "smoke" continues to be emitted from Units 2 and 3. No more white "smoke" was seen coming from Unit 4 as of 21:30 UTC on 25 April.

In Unit 1 fresh water was being continuously injected into the reactor pressure vessel through the feedwater line at an indicated flow rate of 6 m3/h using a temporary electric pump with off-site power. On 27 April at 01:02 UTC an operation was initiated to increase the flow rate for injected water gradually from 6 m3/h to 14 m3/h to determine the amount of water required to flood the reactor core.

In Unit 2 and Unit 3 fresh water is being continuously injected into the reactor pressure vessel through the fire extinguisher line at an indicated rate of 7 m3/h using temporary electric pumps with off-site power.

In Unit 4 water continues to be sprayed on to the spent fuel pool using a concrete pump truck. An amount of 85 tonnes of water was sprayed on 27 April.

Nitrogen gas is still being injected into the containment vessel in Unit 1 to reduce the possibility of hydrogen combustion in the containment vessel. The indicated pressure in the reactor pressure vessel is still increasing.

In Unit 1, the indicated temperature at the feedwater nozzle of the reactor pressure vessel is 132.0 °C and at the bottom of reactor pressure vessel is 110.5 °C.

In Unit 2 the indicated temperature at the feedwater nozzle of the reactor pressure vessel is 120.4 °C. The reactor pressure vessel and the dry well remain at atmospheric pressure. On 26 April an amount of 47.5 tonnes of fresh water was injected into the spent fuel pool using the spent fuel pool clean-up system.

In Unit 3 the indicated temperature at the feed water nozzle of the reactor pressure vessel is 72.0 °C and at the bottom of the reactor pressure vessel is 110.7 °C. The reactor pressure vessel and the dry well remain at atmospheric pressure.

There has been no change in the status in Unit 5 or Unit 6 or in the common spent fuel storage facility.

Spraying of anti-scattering agent at the site is continuing. An area of 7 500 m2 to the east of the Unit 3 turbine building was sprayed on 27 April.

2. Radiation Monitoring

Deposition of Cs-137 was detected in four prefectures on 26 and 27 April, the values reported ranging from 4 Bq/m2 to 29 Bq/m2. I-131 deposition was reported for one prefecture on 26 April, with a value of 3.3 Bq/m2.

Gamma dose rates are measured daily in all 47 prefectures. A general decreasing trend has been observed in all locations since around 20 March. For the Fukushima prefecture gamma dose rates remain at 1.8 µSv/h. In Ibaraki prefecture gamma dose rates were slightly below 0.12 µSv/h. The other 45 prefectures had gamma dose rates of below 0.1 µSv/h, falling within the range of local natural background radiation levels. Gamma dose rates reported specifically for the eastern part of Fukushima prefecture, for distances beyond 30 km from the Fukushima Daiichi plant, showed a similar general decreasing trend, ranging from 0.1 to 13.6 µSv/h, as reported on 26 April.

On-site measurements at the west gate of the Fukushima Daiichi plant indicate the presence of I-131 and Cs-137 in the air in the close vicinity of the plant (within approximately 1 km). The concentrations in air reported since 31 March show a maximum on 14 April of 11.8 x 10−4 Bq/cm3 for total I-131 and 2.7 x 10-4 Bq/cm3 for total Cs-137. The values reported for 26 April are 9.0 x 10−5 Bq/cm3 for total I-131 and 2.4 x 10−5 Bq/cm3 for total Cs-137.

Since 1 April there has been one remaining restriction on the consumption of drinking water relating to I-131 (with a limit of 100 Bq/L), which applies to one village in the Fukushima prefecture and only for infants.

Enforced Plan on Environmental Monitoring

On 22 April the Japanese Ministry of Education, Culture, Sports, Science and Technology (MEXT) issued a press release on an "Enforced plan on environmental monitoring" with the objectives of obtaining an overview and providing data necessary to support the decision to establish the planned evacuation zones.

To meet these objectives, the plan included the following:

  • Collection of data on the distribution of radioactive material inside an appropriate area, including the area in the vicinity of the Fukushima Daiichi plant;
  • Preparation for future evaluations of changes in dose rates and accumulated amounts of radioactive material in all delineated zones around the Fukushima Daiichi plant; and
  • Provision of information on environmental dose rates for the purpose of evaluation of personal radiation doses to local residents.

It was announced that maps will be produced on the basis of the results of environmental monitoring, including maps of dose rates and distributions of radioactivity, estimated accumulated doses and levels of soil surface contamination.

This "enforced plan on environmental monitoring" will be conducted in close cooperation between MEXT, Japan Atomic Energy Agency, universities, the Ministry of Defence, the police, prefectural police, Fukushima prefecture, electrical utilities and others, including the United States Department of Energy.

MEXT will compile all the data collected. MEXT and the Nuclear Safety Commission will cooperate with the Ministry of Economy, Trade and Industry (METI) and other organizations, and will establish procedures for standardizations on ranges and methods for the emergency environmental monitoring.

Food Monitoring

Food monitoring data were reported by the Japanese Ministry of Health, Labour and Welfare on 27 April for a total of 129 samples taken on 21 and 24 - 27 April from 10 prefectures (Chiba, Fukushima, Gunma, Ibaraki, Kanagawa, Miyagi, Niigata, Saitama, Tochigi and Yamagata). Analytical results for 125 of the 129 samples for various vegetables, mushrooms, fruit (strawberries), pork, seafood, fresh milk and raw unprocessed milk indicated that I-131, Cs-134 and Cs-137 were either not detected or were below the regulation values set by the Japanese authorities. In Fukushima prefecture, two samples of spinach from 24 and 25 April and two samples of seafood (sand lance) from 26 April were above the regulation values set by the Japanese authorities for Cs-134/Cs-137.

Food Restrictions

On 27 April restrictions were lifted on the distribution of spinach in Tochigi prefecture. In Fukushima prefecture, restrictions were lifted on the distribution and consumption of head type leafy vegetables from 17 locations in the Aizu and Minamiaizu districts (cities of Aizuwakamatsu and Kitakata; towns of Aizubange, Aizumisato, Bandai, Inawashiro, Kaneyama, Minamiaizu, Mishima, Nishiaizu, Shimogo, Tadami and Yanaizu; villages of Hinoemata, Kitashiobara, Showa and Yugawa) and flower head brassicas from nine locations (city of Shirakawa; towns of Hanawa, Tanagura, Yabuki and Yamatsuri; villages of Izumizaki, Nakajima, Nishigo and Samegawa).

3. Marine Monitoring

Marine Monitoring Programme

The marine monitoring programme is carried out both near the discharge areas of the Fukushima nuclear power plant by TEPCO and at off-shore stations by the Japanese Ministry of Education, Culture, Sports, Science and Technology (MEXT). The locations of the sampling positions, including several new additional positions, were provided in the briefings of 26 April and 27 April. Contamination of the marine environment occurred by aerial deposition and by discharges and outflow of water with contamination.

Monitoring at off-shore sampling positions consists of:

  • Measurement of ambient dose rate in air above the sea;
  • Analysis of ambient dust above the sea;
  • Analysis of surface samples of sea water; and
  • Analysis of samples of sea water collected at 10 m above the sea bottom.

The analysis for almost all sampling positions has shown a general decreasing trend in concentrations of the relevant radionuclides over time. Samples from the coastal positions still show higher concentrations of such radionuclides than samples from the off-shore positions. The radionuclides I-131, Cs-134 and Cs-137 are still detected in most sea water samples, but no longer for some of the off-shore positions.

IAEA Briefing on Fukushima Nuclear Accident (27 April 2011, 18:00 UTC)


Presentation:
Summary of Reactor Status

On Wednesday, 27 April 2011, the IAEA provided the following information on the current status of nuclear safety in Japan:

1. Current Situation

Overall, the situation at the Fukushima Daiichi nuclear power plant remains very serious, but there are signs of recovery in some functions, such as electrical power and instrumentation.

Changes to Fukushima Daiichi Nuclear Power Plant Status

The IAEA receives information from various official sources in Japan through the Japanese national competent authority, the Nuclear and Industrial Safety Agency (NISA).

Management of On-site Contaminated Water

According to the 25 April evaluation by NISA of the report submitted by the Tokyo Electric Power Company (TEPCO), there is a little less than 70 000 tonnes of stagnant water with high-level radioactivity in the basement of the turbine buildings of Units 1, 2 and 3.

Plant Status

On 25 April the power supply for the temporary electrical pumps that supply water to the reactor pressure vessel of Units 1, 2 and 3 was switched from the off-site power supply to temporary diesel generators to allow work to enhance the off-site power supply. The power supply has now been returned to the off-site supply.

White "smoke" continues to be emitted from Units 2 and 3. No more white "smoke" was seen coming from Unit 4 as of 21:30 UTC on 25 April.

In Unit 1 fresh water is being continuously injected into the reactor pressure vessel through the feedwater line at an indicated flow rate of 6 m3/h using a temporary electric pump with off-site power.

In Unit 2 and Unit 3 fresh water is being continuously injected into the reactor pressure vessel through the fire extinguisher line at an indicated rate of 7 m3/h using temporary electric pumps with off-site power.

In Unit 4 140 tonnes of fresh water was sprayed over the spent fuel pool on 23 April and 165 tonnes of fresh water was sprayed over the spent fuel pool on 24 April using a concrete pump truck. The nuclear emergency response headquarters reported that temperature measurements showed the spent fuel pool temperature to be 83 °C before spraying and 66 °C after spraying on 23 April, and the spent fuel pool temperature to be 86 °C before spraying and 81 °C after spraying on 24 April.

Nitrogen gas continues to be injected into the containment vessel in Unit 1 to reduce the possibility of hydrogen combustion in the containment vessel. The pressure in the reactor pressure vessel is increasing.

The reactor pressure vessel temperatures in Unit 1 remain above cold shutdown conditions. The indicated temperature at the feedwater nozzle of the reactor pressure vessel is 134.7 °C and at the bottom of reactor pressure vessel is 110.9 °C.

The reactor pressure vessel temperatures in Unit 2 remain above cold shutdown conditions. The indicated temperature at the feed water nozzle of the reactor pressure vessel is 121.2 °C. The reactor pressure vessel and the dry well remain at atmospheric pressure. Fresh water injection (a total of 135 tonnes) to the spent fuel pool via the spent fuel pool cooling line was carried out from 19 to 25 April.

The temperature at the bottom of the reactor pressure vessel in Unit 3 remains above cold shutdown conditions. The indicated temperature at the feed water nozzle of the reactor pressure vessel is 67.9 °C and at the bottom of the reactor pressure vessel is 110.4 °C. The reactor pressure vessel and the dry well remain at atmospheric pressure.

There has been no change in the status in Unit 5 or Unit 6 or in the common spent fuel storage facility.

2. Radiation Monitoring

On 25 April deposition of Cs-137 was detected in five prefectures, the values reported ranging from 3.2 to 20 Bq/m2.

Gamma dose rates are measured daily in all 47 prefectures. A general decreasing trend has been observed in all locations since around 20 March. For Fukushima prefecture, gamma dose rates in recent days were in the range 1.7-1.8 µSv/h. In Ibaraki prefecture, gamma dose rates were slightly below 0.12 µSv/h. In all other prefectures, reported gamma dose rates were below 0.1 µSv/h with similar decreasing trends.

Gamma dose rates reported specifically for the eastern part of Fukushima prefecture, for distances beyond 30 km from Fukushima Daiichi, showed a similar general decreasing trend, ranging from 0.1 to 19.4 µSv/h, as reported on 25 April. The other 45 prefectures had gamma dose rates of below 0.1 µSv/h, falling within the local natural background range.

In drinking water, I-131 or Cs-137 is detectable, but in only a few prefectures. As of 1 April, the one remaining restriction on the consumption of drinking water relating to I-131 (at a level of 100 Bq/L) applies to only one village in the Fukushima prefecture, and the restriction applies only to infants.

Food Monitoring

Food monitoring data were reported by the Japanese Ministry of Health, Labour and Welfare on 26 April for a total of 39 samples taken on 22 and 24 - 26 April from eight prefectures (Chiba, Fukushima, Gunma, Hokkaido, Ibaraki, Kanagawa, Niigata and Yamagata). Analytical results for all of the samples of various vegetables, mushrooms, beef, seafood and raw unprocessed milk indicated that I-131, Cs-134 and Cs-137 were either not detected or were below the regulation values set by the Japanese authorities.

3. Marine Monitoring

Marine Monitoring Programmes

The marine monitoring programme is carried out both near the discharge areas of the Fukushima nuclear power plant by TEPCO and at off-shore stations by the Japanese Ministry of Education, Culture, Sports, Science and Technology (MEXT). The locations of the sampling positions, including several new additional positions, were given in the briefing of 26 April (see Fig. 1: Locations of TEPCO and MEXT Seawater Sampling Positions). Contamination of the marine environment occurred by aerial deposition and by discharges and outflow of contaminated water.

Monitoring at off-shore sampling positions consists of:

  • Measurement of ambient dose rate in air above the sea;
  • Analysis of ambient dust above the sea;
  • Analysis of surface samples of seawater; and
  • Analysis of samples of seawater collected at 10 m above the sea bottom.

Fig. 1: Locations of TEPCO and MEXT Seawater Sampling Positions

TEPCO and MEXT Seawater Sampling Positions

IAEA Briefing on Fukushima Nuclear Accident (26 April 2011, 18:00 UTC)


Presentation:
Summary of Reactor Status

On Tuesday, 26 April 2011, the IAEA provided the following information on the current status of nuclear safety in Japan:

1. Current situation

Overall, the situation at the Fukushima Daiichi nuclear power plant remains very serious, but there are signs of recovery in some functions, such as electrical power and instrumentation.

After the announcement on 11 April by the Government of Japan to establish "planned evacuation zones" and "emergency evacuation preparation zones", in a Press Conference on 22 April by the chief cabinet secretary of Japan Mr. Edano it was stated that "the Prime Minister, as head of the Nuclear Emergency Response Headquarters, has issued instructions to the governor of Fukushima Prefecture and the heads of municipal governments concerned." These instructions included:

  • Designation of "planned evacuation zones" to be applied to some specific zones outside the 20 km radius from the Fukushima Daiichi plant: "the villages of Katsurao, Namie and Iitate, part of the town of Kawamata, and part of the city of Minamisoma," where planned evacuations are expected to be implemented in approximately one month's time.
  • Designation of "emergency evacuation preparation zones," to be applied to the area within a 20 - 30 km radius from the Fukushima Daiichi plant (except for areas designated as planned evacuation zones): "the towns of Hirono and Naraha, the village of Kawauchi and parts of the cities of Tamura and Minamisoma," in which preparations should be made so that the residents can take shelter indoors or can evacuate by their own means in the event of an emergency. In addition, with regard to the areas located within a 20 - 30 km radius from the nuclear power plant, the advisory for sheltering indoors that has been in effect to date has been lifted.

Changes to Fukushima Daiichi Nuclear Power Plant Status

The IAEA receives information from various official sources in Japan through the Japanese national competent authority, the Nuclear and Industrial Safety Agency (NISA).

Management of On-site Contaminated Water

According to the 25 April evaluation by NISA of the report submitted by TEPCO, there is a little less than 70 000 tonnes of stagnant water with high-level radioactivity in the basement of the turbine buildings of Units 1, 2 and 3.

Plant Status

On 25 April the power supply for the temporary electrical pumps that supply water to the reactor pressure vessel of Units 1, 2 and 3 was switched from the off-site power supply to temporary diesel generators to allow work to enhance the off-site supply.

White "smoke" continues to be emitted from Units 2, 3 and 4.

In Unit 1 fresh water is being continuously injected into the reactor pressure vessel through the feedwater line at an indicated flow rate of 6 m3/h using a temporary electric pump with off-site power.

In Unit 2 and Unit 3 fresh water is being continuously injected into the reactor pressure vessel through the fire extinguisher line at an indicated rate of 7 m3/h using temporary electric pumps with off-site power.

In Unit 4 140 tonnes of fresh water was sprayed over the spent fuel pool on 23 April and 165 tonnes of fresh water was sprayed over the spent fuel pool on 24 April using a concrete pump truck. The nuclear emergency response headquarters reported that temperature measurements showed the spent fuel pool temperature to be 83 °C before spraying and 66 °C after spraying on 23 April, and the spent fuel pool temperature to be 86 °C before spraying and 81 °C after spraying on 24 April.

Nitrogen gas is being injected into the containment vessel in Unit 1 to reduce the possibility of hydrogen combustion in the containment vessel. The pressure in the reactor pressure vessel is increasing.

The reactor pressure vessel temperatures in Unit 1 remain above cold shutdown conditions. The indicated temperature at the feedwater nozzle of the reactor pressure vessel is 138 °C and at the bottom of reactor pressure vessel is 111 °C.

The reactor pressure vessel temperatures in Unit 2 remain above cold shutdown conditions. The indicated temperature at the feed water nozzle of the reactor pressure vessel is 123 °C. The reactor pressure vessel and the dry well remain at atmospheric pressure. Fresh water injection (approximately 38 tonnes) to the spent fuel pool via the spent fuel pool cooling line was carried out on 25 April.

The temperature at the bottom of the reactor pressure vessel in Unit 3 remains above cold shutdown conditions. The indicated temperature at the feed water nozzle of the reactor pressure vessel is 75 °C and at the bottom of the reactor pressure vessel is 111 °C. The reactor pressure vessel and the dry well remain at atmospheric pressure.

There has been no change in the status in Unit 5 or Unit 6 or in the common spent fuel storage facility.

2. Radiation Monitoring

For the period 21 - 25 April deposition of I-131 was detected in eight prefectures, ranging from 2.2 to 37 Bq/m2. Deposition of Cs-137 was detected in 11 prefectures, the values reported ranging from 1.3 to 69 Bq/m2.

Gamma dose rates are measured daily in all 47 prefectures. For Fukushima prefecture gamma dose rates decreased from 1.9 µSv/h on 21 April to 1.7 µSv/h on 23 April. In Ibaraki prefecture, gamma dose rates were 0.12 µSv/h. In all other prefectures, reported gamma dose rates were below 0.1 µSv/h with similar decreasing trends.

Gamma dose rates reported specifically for the eastern part of Fukushima prefecture, for distances beyond 30 km from Fukushima Daiichi, showed a similar general decreasing tendency, ranging from 0.1 to 19.4 µSv/h on 25 April. The latest maximum reported value for 20 April was 24 µSv/h.

The other 45 prefectures presented gamma dose rates of below 0.1 µSv/h, falling within the local natural background range.

In drinking water, I-131 or Cs-137 is detectable, but in only a few prefectures. As of 1 April, the one remaining restriction on the consumption of drinking water relating to I-131 (at a level of 100 Bq/L) applies to only one village in the Fukushima prefecture, and the restriction applies only to infants.

Food Monitoring

Food monitoring data were reported by the Japanese Ministry of Health, Labour and Welfare on 21 April for a total of 62 samples taken over 18 - 21 April from 11 prefectures (Chiba, Fukushima, Gunma, Ibaraki, Kanagawa, Nagano, Niigata, Saitama, Tochigi, Tokyo and Yamagata). Analytical results for all of the samples of various vegetables, mushrooms, seafood and unprocessed raw milk indicated that I-131, Cs-134 and Cs-137 were either not detected or were below the regulation values set by the Japanese authorities.

Food monitoring data were reported by the Japanese Ministry of Health, Labour and Welfare on 22, 23 and 24 April for a total of 164 samples taken in the period 19-23 April from 11 prefectures (Chiba, Fukushima, Gifu, Gunma, Hyogo, Ibaraki, Kanagawa, Niigata, Saitama, Tochigi and Yamagata). Analytical results for 158 of the 164 samples of various vegetables, mushrooms, fruit (strawberries), seafood and raw unprocessed milk indicated that I-131, Cs-134 and Cs-137 were either not detected or were below the regulation values set by the Japanese authorities. Six samples of shiitake mushrooms (grown outdoors) taken in Fukushima prefecture on 21 April were above the regulation values set by the Japanese authorities for Cs-134/Cs-137.

Food monitoring data were reported by the Japanese Ministry of Health, Labour and Welfare on 25 April for a total of 15 samples taken on 21 and 24 - 25 April from seven prefectures (Fukushima, Gunma, Ibaraki, Kanagawa, Niigata, Tochigi and Yamagata). Analytical results for all of the samples of various vegetables, fruit (strawberries), beef, milk and raw unprocessed milk indicated that I-131, Cs-134 and Cs-137 were either not detected or were below the regulation values set by the Japanese authorities.

Food Restrictions

On 21 April restrictions on the distribution of raw unprocessed milk produced in Soma City and Shinchi town in Fukushima prefecture were lifted, as well as the restriction on the distribution of spinach from Nasushiobara City and Shioya town in Tochigi prefecture. On 22 April, the restrictions on the distribution of spinach, shungiku, qing-geng-cai, sanchu, celery and parsley produced in Chiba prefecture were also lifted.

On 22 April the chief cabinet secretary, Mr. Edano, announced that "a decision has been made to prohibit the cultivation of rice for the duration of the 2011 harvest within the evacuation zones, planned evacuation zones and emergency evacuation preparation zones," in Fukushima prefecture. This measure concerns rice grown for human consumption on the land most affected by the deposition of radionuclides.

On 25 April in Fukushima prefecture restrictions on the distribution of shiitake mushrooms produced in Iwaki City were lifted. Restrictions were placed on the distribution of shiitake mushrooms from Motomiya City.

3. Marine Monitoring

Marine Monitoring Programmes

Further to previous briefings, new monitoring points have been announced by TEPCO, with sampling starting 25 April. Fig. 1 shows existing and new TEPCO sampling points, as well as existing and new MEXT sampling points.

The Japanese Ministry of Education, Culture, Sports, Science and Technology (MEXT) added further sampling points in its off-shore monitoring programme on 25 April (see Fig. 1). In addition, sampling has started (on 25 April) in five off-shore points off Ibaraki Prefecture.

Fig. 1: TEPCO and MEXT Seawater Sampling Locations:

TEPCO and MEXT Seawater Sampling Locations

Monitoring at off-shore sampling points consists of:

  • Measurement of ambient dose rate in air above the sea;
  • Analysis of ambient dust above the sea;
  • Analysis of surface samples of seawater; and
  • Analysis of samples of seawater collected at 10 m above the sea bottom.

IAEA Briefing on Fukushima Nuclear Accident (21 April 2011, 16:25 UTC)


Presentation:
Summary of Reactor Status

(Note: Unless there are significant developments, no further written brief will be issued until Tuesday 26 April.)

On Thursday, 21 April 2011, the IAEA provided the following information on the current status of nuclear safety in Japan:

1. Current Situation

Overall, the situation at the Fukushima Daiichi nuclear power plant remains very serious, but there are signs of recovery in some functions, such as electrical power and instrumentation.

At a press conference held at 11:00 (Japan local time) on 21 April, the chief cabinet secretary, Mr. Edano, announced the establishment of a no entry zone around Fukushima Daiichi nuclear power plant, as well as basic policies concerning temporary re-entry. As of midnight (Japan local time) on 22 April 2011, the area within 20 km of Fukushima Daiichi nuclear power plant is announced as a no entry zone.

Chief cabinet secretary, Mr. Edano, also announced a re-designation of the evacuation zone around Fukushima Daini nuclear power plant. He announced that "the size of the evacuation zone around the station would be reduced from 10 km to 8 km," and that "the order to evacuate based on the incident at Fukushima Daini nuclear power station would be lifted from areas farther than 8 km around the station."

Changes to Fukushima Daiichi Nuclear Power Plant Status

The IAEA receives information from a variety of official Japanese sources through the Japanese national competent authority, the Nuclear and Industrial Safety Agency.

Management of On-site Contaminated Water

Injection of approximately 17 000 L of coagulant (liquid glass) to the power cable trench of Unit 2 was carried out on 18 April and injection of approximately 7 000 L of liquid glass on 19 April. The transfer of stagnant water from the Unit 2 turbine building to radioactive waste treatment facilities commenced on 19 April.

The stagnant water (around 100 m3) in the basement of the turbine building of Unit 6 was transferred to the condenser on 19 April.

Plant status

Work to strengthen the electrical power system between Units 1 - 2 and Units 3 - 4 by establishing multiple power lines was completed on 19 April.

White "smoke" continues to be emitted from Units 2, 3 and 4.

In Unit 1 fresh water is being continuously injected into the reactor pressure vessel through the feedwater line at an indicated flow rate of 6 m3/h using a temporary electric pump with off-site power.

In Unit 2 and Unit 3 fresh water is being continuously injected into the reactor pressure vessel through the fire extinguisher line at an indicated rate of 7 m3/h using temporary electric pumps with off-site power.

In Unit 4 40 tonnes of fresh water was sprayed over the spent fuel pool on 19 April using a concrete pump truck.

Nitrogen gas is being injected into the containment vessel in Unit 1 to reduce the possibility of hydrogen combustion in the containment vessel. The pressure in the containment vessel has stabilized. The pressure in the reactor pressure vessel is increasing.

The reactor pressure vessel temperatures in Unit 1 remain above cold shutdown conditions. The indicated temperature at the feedwater nozzle of the reactor pressure vessel is 154 °C and at the bottom of reactor pressure vessel is 113 °C.

The reactor pressure vessel temperatures in Unit 2 remain above cold shutdown conditions. The indicated temperature at the feed water nozzle of the reactor pressure vessel is 135 °C. The reactor pressure vessel and the dry well remain at atmospheric pressure. Fresh water injection (approximately 47 tonnes) to the spent fuel pool via the spent fuel pool cooling line was carried out on 19 April.

The temperature at the bottom of the reactor pressure vessel in Unit 3 remains above cold shutdown conditions. The indicated temperature at the feed water nozzle of the reactor pressure vessel is 100 °C and at the bottom of the reactor pressure vessel is 108 °C. The reactor pressure vessel and the dry well remain at atmospheric pressure.

There has been no change in the status in Unit 6 or in the common spent fuel storage facility.

2. Radiation Monitoring

On 20 April, deposition of I-131 was detected in 8 prefectures, ranging from 2.4 to 80 Bq/m2. Deposition of Cs-137 was detected in seven prefectures, the values reported ranging from 2.6 to 87 Bq/m2.

Gamma dose rates are measured daily in all 47 prefectures. For Fukushima on 20 April a gamma dose rate of 1.9 µSv/h was reported, and for Ibaraki prefecture a gamma dose rate of 0.12 µSv/h was reported. In all other prefectures, reported gamma dose rates were below 0.1 µSv/h.

Dose rates are also reported specifically for the eastern part of Fukushima prefecture, for distances beyond 30 km from Fukushima Daiichi. On 19 April the values in this area ranged from 0.1 to 22 µSv/h.

In cooperation with local universities, the Japanese Ministry of Education, Culture, Sports, Science and Technology (MEXT) has set up an additional monitoring programme. For 20 April, measurements of gamma dose rates were reported for 54 cities in 40 prefectures. In Fukushima City a value of 0.42 µSv/h was reported. For nine cities, gamma dose rates between 0.13 and 0.17 µSv/h were reported. For all other cities reported gamma dose rates were below 0.1 µSv/h.

I-131 or Cs-137 is detectable in drinking water, but at levels below 1 Bq/L and in only a few prefectures. As of 20 April, one restriction on drinking water for infants relating to I-131 (100 Bq/L) remains in place for a small scale water supply in a village of the Fukushima prefecture.

Food monitoring data reported by the Japanese Ministry of Health, Labour and Welfare on 20 April covered a total of 103 samples. These samples were taken on 3, 14, 15, 18, 19 and 20 April from nine prefectures (Chiba, Fukushima, Gunma, Ibaraki, Kanagawa, Niigata, Tochigi, Tokyo and Yamagata).

Analytical results for 99 samples of various vegetables, shiitake mushrooms, fruit (strawberries), fish, seafood and unprocessed raw milk indicated that I-131, Cs-134 and Cs-137 were either not detected or had levels below the regulation values set by the Japanese authorities. Four samples of leafy vegetables (Japanese parsley, komatsuna, shinobuhuyuna and spinach) taken on 18 April from Fukushima prefecture had levels above the regulation values set by the Japanese authorities for radioactive caesium.

On 20 April, restrictions were placed on the distribution and consumption of the young of a specific sea fish (sand lance) from the coastal region of Fukushima prefecture. As has been reported previously, sand lance is the only seafood that has been found with I-131, Cs-134 or Cs-137 levels above the regulation values set by the Japanese authorities.

3. Marine Monitoring

TEPCO Seawater Monitoring Programme

TEPCO is conducting a programme for seawater monitoring (by surface sampling) at a number of near-shore and off-shore monitoring locations. Following a directive from NISA, on 16 April TEPCO announced that it will increase the number of sea sampling points from ten to 16. A further four points are to be added at 3 km from the coast and two points are to be added at 8 km from the coast. The new sampling sites are indicated on Map 1: TEPCO Seawater Sampling Locations, on which new points are indicated with green bullets.

On some days, two samples were collected at the same sampling point, a few hours apart, and analysed separately.

Until 3 April a generally decreasing trend in radioactivity was observed at the sampling points TEPCO 1 to TEPCO 4. After the discharge of contaminated water from the plant on 4 April, a temporary increase in radioactivity in sea water was reported. Since 5 April a general downward trend in the concentration of radionuclides in sea water for all TEPCO sampling points has been observed.

On 21 April new data for TEPCO sampling points were reported. For TEPCO 1 - 4 (sampling date 19 April) the values for both I-131 and Cs-137 were below 0.5 kBq/L. For TEPCO 5 - 10 (sampling date 18 April) the values for both I-131 and Cs-137 were below 0.3 kBq/L.

For the six new stations at 3 km off-shore and 8 km off-shore (green bullets in Map 1; sampling date 18 April), I-131 and Cs-137 were not detectable at the two stations 3 km off-shore; for all the other stations the level of I-131 was below 0.3 kBq/L and that of Cs-137 was below 0.4 kBq/L.

Map 1: TEPCO Seawater Sampling Locations:

TEPCO Seawater Sampling Locations

MEXT Off-shore Seawater Monitoring Programme

On 21 April new data were reported (sampling date 19 April)for the MEXT 2, 4, 6, 8, 10 and B off-shore seawater sampling locations shown in Map 2: MEXT Seawater Sampling Locations. I-131 was detected only at the location MEXT 6 and the level was below 20Bq/L. Cs-137 was detected at locations MEXT 6 and 8 at a level of below 30 Bq/L.

Map 2: MEXT Seawater Sampling Locations:

MEXT Seawater Sampling Locations

4. IAEA Activities

Georgia and Iceland have also provided monitoring data, in addition to the States that have been mentioned in previous briefs.

On 18 April the IAEA monitoring team finished its radiological monitoring campaign and the team returned to Vienna on 20 April.

IAEA Briefing on Fukushima Nuclear Accident (20 April 2011, 16:00 UTC)


Presentation:
Summary of Reactor Status

On Wednesday, 20 April 2011, the IAEA provided the following information on the current status of nuclear safety in Japan:

1. Current Situation

Overall, the situation at the Fukushima Daiichi nuclear power plant remains very serious, but there are early signs of recovery in some functions, such as electrical power and instrumentation.

Changes to Fukushima Daiichi Nuclear Power Plant Status

The IAEA receives information from a variety of official Japanese sources through the Japanese national competent authority, the Nuclear and Industrial Safety Agency (NISA).

Management of On-Site Contaminated Water

TEPCO has provided a plan to NISA for the transfer of highly contaminated water from the basement of the turbine building of Unit 2 to the main building of the radioactive waste treatment facilities, to reduce the risk of this stagnant waste water being discharged to the environment. Measures to ensure that the radioactive waste treatment facility is watertight were completed on 18 April and the transfer of water from Unit 2 was commenced on 19 April.

Plant Status

Work to strengthen the electrical power system between Units 1 - 2 and Units 3 - 4 was completed on 19 April. White "smoke" continues to be emitted from Units 2, 3 and 4.

In Unit 1 fresh water is being continuously injected into the reactor pressure vessel through the feedwater line at an indicated flow rate of 6 m3/h using a temporary electric pump with off-site power. In Units 2 and 3 fresh water is being continuously injected into the reactor pressure vessel through the fire extinguisher line at an indicated rate of 7 m3/h using a temporary electric pump with off-site power. In Unit 4 fresh water continues to be sprayed onto the spent fuel pool using a concrete pump truck.

Nitrogen gas is being injected into the containment vessel in Unit 1 to reduce the possibility of hydrogen combustion within the containment vessel. The pressure in the containment vessel has stabilized. The pressure in the reactor pressure vessel is increasing.

The reactor pressure vessel temperatures in Unit 1 remain above cold shutdown conditions. The indicated temperature at the feedwater nozzle of the reactor pressure vessel is 164 °C and that at the bottom of reactor pressure vessel is 114 °C.

The reactor pressure vessel temperatures in Unit 2 remain above cold shutdown conditions. The indicated temperature at the feed water nozzle of the reactor pressure vessel is 133 °C. The reactor pressure vessel and the dry well remain at atmospheric pressure.

The temperature at the bottom of the reactor pressure vessel in Unit 3 remains above cold shutdown conditions. The indicated temperature at the feed water nozzle of the reactor pressure vessel is 99 °C and that at the bottom of reactor pressure vessel is 110 °C. The reactor pressure vessel and the dry well remain at atmospheric pressure.

There has been no change in the status in Units 5 and 6 or in the common spent fuel storage facility.

2. Radiation Monitoring

On 19 April, deposition of I-131 was detected in 13 prefectures, ranging from 1.8 to 368 Bq/m2. Deposition of Cs-137 was detected in seven prefectures, the values reported ranging from 2.4 to 160 Bq/m2.

Gamma dose rates are measured daily in all 47 prefectures. For Fukushima on 20 April a gamma dose rate of 1.9 µSv/h was reported, and for Ibaraki prefecture a gamma dose rate of 0.13 µSv/h was reported. In all other prefectures, reported gamma dose rates were below 0.1 µSv/h.

In cooperation with local universities, the Japanese Ministry of Education, Culture, Sports, Science and Technology (MEXT) has set up an additional monitoring programme. For 19 April, measurements of the gamma dose rates were reported for 53 cities in 40 prefectures. In Fukushima City a value of 0.42 µSv/h was reported. For all other cities reported gamma dose rates were below 0.13 µSv/h.

In drinking water, I-131 or Cs-137 is detectable, but at levels below 1 Bq/L and in only a few prefectures. As of 17 April, one restriction on drinking water for infants relating to I-131 (100 Bq/L) is in place in a small scale water supply in a village of the Fukushima prefecture.

Food monitoring data reported by the Japanese Ministry of Health, Labour and Welfare on 19 April covered a total of 36 samples. These were taken on 4, 18 and 19 April from eight prefectures (Chiba, Fukushima, Gunma, Ibaraki, Kanagawa, Nagano, Niigata and Saitama). Analytical results for 35 of the samples of various vegetables, shiitake mushrooms, fruit (strawberries), edible shoots (Japanese Angelica tree), seafood, yoghurt and unprocessed raw milk indicated that I-131, Cs-134 and Cs-137 were either not detected or were below the regulation values set by the Japanese authorities. One sample of seafood (sand lance) taken on 18 April from the coastal region of Fukushima had levels above the regulation values set by the Japanese authorities for I-131 and also for radioactive caesium.

3. Marine Monitoring

TEPCO Monitoring Programme

TEPCO is conducting a programme for seawater monitoring (by surface sampling) at a number of near-shore and off-shore monitoring locations. Following a directive from NISA, on 16 April TEPCO announced that it will increase the number of sea sampling points from ten to 16. A further four points are to be added at 3 km from the coast and two points are to be added at 8 km from the coast. The new sampling sites are indicated on Map 1: TEPCO Seawater Sampling Locations, on which new points are indicated with green bullets.

On some days, two samples were collected at the same sampling point, a few hours apart, and analysed separately.

Until 3 April a generally decreasing trend in radioactivity was observed at the sampling points TEPCO 1 to TEPCO 4. After the discharge of contaminated water from the plant on 4 April, a temporary increase in radioactivity in seawater was reported. Since 5 April a general downward trend in the concentration of radionuclides in seawater for all TEPCO sampling points has been observed.

On 20 April no new data for TEPCO 1 - 4 sampling points were reported. For TEPCO 5 - 10, data for TEPCO 8 only were reported on 20 April (for sampling on 17 April). Both I-131 and Cs-137 were below 0.1 kBq/L.

Map 1: TEPCO Seawater Sampling Locations:

TEPCO Seawater Sampling Locations

MEXT Off-shore Monitoring Programme

On 20 April no new data were reported for the MEXT off-shore sampling locations shown on Map 2: MEXT Seawater sampling Locations.

Map 2: MEXT Seawater Sampling Locations:

MEXT Seawater Sampling Locations

4. IAEA Activities

Sri Lanka has also provided monitoring data, in addition to the countries that have been mentioned in previous briefs.

On 18 April the IAEA monitoring team finished its radiological monitoring campaign and the team is to return to Vienna on 20 April.

IAEA Briefing on Fukushima Nuclear Accident (19 April 2011, 18.00 UTC)


Presentations:
Summary of Reactor Status
Fukushima Radiological Monitoring and Consequences
Fukushima Marine Environment Monitoring
Watch Video

On Tuesday, 19 April 2011, the IAEA provided the following information on the current status of nuclear safety in Japan:

1. Current Situation

Overall, the situation at the Fukushima Daiichi nuclear power plant remains very serious but there are early signs of recovery in some functions, such as electrical power and instrumentation.

On 17 April, the Ministry of Economy, Trade and Industry (METI) announced that TEPCO had issued a "Roadmap towards Restoration from the Accident at the Fukushima Daiichi Nuclear Power Station". The roadmap outlines 63 measures to be taken in two steps over a period of six to nine months.

Changes to Fukushima Daiichi Nuclear Power Plant Status

The IAEA receives information from a variety of official Japanese sources through the nation's national competent authority, the Nuclear and Industrial Safety Agency.

TEPCO has provided a plan to NISA for the transfer of highly contaminated water from the basement floor of the turbine building of Unit 2 to the Main Building of the Radioactive Waste Treatment Facilities in order to reduce the risk of this stagnant waste water being discharged to the environment.

On 17 and 18 April, an unmanned robot was used to conduct inspections of the Reactor Buildings in Units 1, 2 and 3.

As of 18 April, white "smoke" was still observed coming from Units 2, 3 and 4.

In Unit 1, fresh water is being continuously injected into the RPV through the feed-water line at an indicated flow rate of 6 m3/h using a temporary electric pump with off-site power. In Units 2 and 3, fresh water is being continuously injected through the fire extinguisher lines at an indicated rate of 7 m3/h using temporary electric pumps with off-site power.

RPV temperatures remain above cold shutdown conditions in all Units. In Unit 1 the temperature at the feed water nozzle of the RPV is 170 °C and at the bottom of the RPV is 115 °C. In Unit 2, the temperature at the feed water nozzle of the RPV is 142 °C. In Unit 3 the temperature at the feed water nozzle of the RPV is 100 °C and at the bottom of the RPV is 114 °C.

In Unit 1 Nitrogen gas is being injected into the containment vessel to reduce the possibility of hydrogen combustion within the containment vessel. The pressure in this containment vessel has stabilised. The pressure in the RPV is increasing. In Units 2 and 3 Reactor Pressure Vessel and Drywell pressures remain at atmospheric pressure.

On 18 April the concrete pump truck sprayed water into the Unit 3 spent fuel pool. On 17 April, approximately 140 tonnes of fresh water was pumped into the Unit 4 spent fuel pool.

There has been no change in the status in Units 5 and 6 or in Common Spent Fuel Storage Facility.

On 17 and 18 April, anti-scattering agent was sprayed over an additional 3100 m2 area near the Centralized Waste Treatment Facility.

2. Radiation Monitoring

On 18 April, deposition of I-131 was detected in 6 prefectures ranging from 2.3 to 65 Bq/m2. Deposition of Cs-137 was detected in 2 prefectures; the values reported were 4.7 and 14.8 Bq/m2.

Gamma dose rates are measured daily in all 47 prefectures. The values tend to decrease over time. For Fukushima, on 18 April a dose rate of 1.9 µSv/h was reported. In the Ibaraki prefecture, a gamma dose rate of 0.13 µSv/h was reported; in all other prefectures, reported gamma dose rates were below 0.1 µSv/h.

Dose rates are also reported specifically for the Eastern part of the Fukushima prefecture, for distances beyond 30 km from Fukushima-Daiichi. On 17 April, the values in this area ranged from 0.1 to 23 µSv/h.

MEXT has set up an additional monitoring programme in cooperation with local universities. For 18 April, measurements of the gamma dose rates were reported for 53 cities in 40 prefectures. In Fukushima City, a value of 0.38 µSv/h was observed; in 9 cities, gamma dose rates ranged from 0.13 to 0.17 µSv/h. For the other cities, gamma dose rates of less than 0.1 µSv/h were reported.

In drinking water, I-131 or Cs-137 is detectable at very low levels only in a few prefectures. As of 17 April, one restriction for infants related to I-131 (100 Bq/l) is in place in a small scale water supply in a village of the Fukushima prefecture.

On 18 April, the IAEA Team made measurements at 12 different locations in the Fukushima area at distances ranging from 13 to 43 km, South and Southwest from the Fukushima nuclear power plant. At these locations, the dose rates ranged from 0.25 to 6.8 µSv/h. At the same locations, results of beta-gamma contamination measurements ranged from 0.01 to 0.15 Megabecquerel/m2.

Analytical results related to food contamination were reported by the Japanese Ministry of Health, Labour and Welfare on 18 April, and covered a total of 23 samples taken on 8, 15, 17 and 18 April. Analytical results for all of the samples of various vegetables, shiitake mushrooms, leafy vegetables, fruit (strawberries), fish and unprocessed raw milk in eight prefectures (Chiba, Fukushima, Gunma, Hokkaido, Ibaraki, Niigata, Saitama and Yamagata) indicated that I-131, Cs-134 and/or Cs-137 were either not detected or were below the regulation values set by the Japanese authorities.

3. Marine Monitoring

TEPCO Monitoring Programme

TEPCO is conducting a programme for seawater (surface sampling) at a number of near-shore and off-shore monitoring locations following a directive from NISA, on 16 April TEPCO announced they will increase the number of sea sampling points from 10 to 16. A further four points will be added at 3 km from the coast and two points will be added at 8 km from the coast. The new sampling sites are indicated on the map below. (See Map 1: TEPCO Seawater Sampling Locations, new points indicated with green bullets).

On some days, two samples were collected at the same sampling point, a few hours apart and analysed separately.

Until 3 April a general decreasing trend in radioactivity was observed at the sampling points TEPCO 1 to TEPCO 4. After the discharge of contaminated water on 4 April, a temporary increase in radioactivity has been reported. Again since 5 April, general decreasing trend has been observed in the concentration of radionuclides in sea water for all TEPCO sampling points.

On 18 April new data for TEPCO sampling points have been reported (sampling date 15 April). Since 9 April the levels of I-131 and Cs-137 at the sampling points TEPCO number 5-10 are lower than those at the near-shore stations (below 0.5 kBq/l) and the levels of I-131 and Cs-137 at the sampling points TEPCO 1 - 4 are below 20 kBq/l. At all TEPCO sampling points since 9 April a decreasing trend has been observed.

MEXT Off-shore Monitoring Programme

The Japanese Ministry of Education, Culture, Sports, Science and Technology (MEXT) initiated the off-shore monitoring program on 23 March and subsequently 4 points were added to the off-shore sampling scheme. On 4 April, MEXT added two sampling points to the north and west of sampling point 1. These are referred to as points A and B. (See Map2: MEXT Seawater Sampling Locations).

The results reported on 18 April (sampling date 15 April) showed that Cs-137 and I-131 were detected at MEXT 4, 6 and 8. The highest concentrations were recorded at MEXT 4 (below 200Bq/l for Cs-137 and about 160 Bq/l for I-131). At MEXT 6 and 8 sampling locations both Cs-137 and I-131 were reported at levels below about 40 Bq/l.

The results reported on 19 April (sampling date 17 April) showed that at the stations MEXT 5, 7 and 9, Cs-137 and I-131 are below 90 Bq/l.

Neither Cs-137 nor I-131 have been detected at MEXT A and B. (See Map 2: MEXT Seawater Sampling Locations).

Map 1: TEPCO Seawater Sampling Locations:

TEPCO Seawater Sampling Locations

Map 2: MEXT Seawater Sampling Locations:

MEXT Seawater Sampling Locations

4. IAEA Activities

The mission of BWR expert to Japan provided the IAEA with a unique opportunity to communicate directly with the various stakeholders working to address challenges at both the Daiichi and Daini reactor sites. All organizations fully cooperated with the IAEA team and provided the team with a better understanding of event sequences, current challenges and future plans and priorities.

The IAEA team of BWR experts toured the Fukushima Daiichi site and the Emergency center. The team was also able to tour the Fukushima Daini site. At all facilities, the IAEA team noted a strong, positive attitude broadly displayed by the management, support and task implementation teams, even though the situation is not yet stabilized. Activities appeared to be well organized, efforts were thoroughly planned, and responsibilities well communicated.

IAEA Briefing on Fukushima Nuclear Accident (18 April 2011, 15:35 UTC)


Presentation:
Summary of Reactor Status

On Monday, 18 April 2011, the IAEA provided the following information on the current status of nuclear safety in Japan:

1. Current Situation

Overall, the situation at the Fukushima Daiichi nuclear power plant remains very serious but there are early signs of recovery in some functions, such as electrical power and instrumentation.

On 17 April, the Ministry of Economy, Trade and Industry (METI) announced that TEPCO had issued a "Roadmap towards Restoration from the Accident at the Fukushima Daiichi Nuclear Power Station." The roadmap outlines 63 measures to be taken in two steps over a period of six to nine months. TEPCO declared they will "make every effort to enable evacuees to return to their homes and for all citizens to be able to secure a sound life."

Changes to Fukushima Daiichi Nuclear Power Plant Status

The IAEA receives information updates from a variety of official Japanese sources, through the national competent authorities: the Nuclear and Industrial Safety Agency (NISA) and the Ministry of Education, Culture, Sports, Science and Technology (MEXT).

Based on the information received by 18 April 2011, 02:00 UTC the following update related to the reactor units at the Fukushima Daiichi Nuclear Power Plant and related environmental conditions is provided.

As a countermeasure against a possible tsunami, the distribution boards for the pumps injecting water to the reactor pressure vessels of Units 1, 2 and 3 were transferred to higher ground on 15 April. In order to minimize the liberation of radioactive material into the ocean, two sandbags filled with Zeolite were placed between the Inlet Screen Pump Room of Unit 1 and Unit 2. Further, five sandbags filled with Zeolite were placed between the Inlet Screen Pump Room of Unit 2 and Unit 3 on 17 April. The Zeolite material is designed to capture specific radioactive elements. It is intended to sample and analyze the Zeolite material periodically to determine the effectiveness of this procedure.

The removal of debris (amount equivalent to 8 containers) using remote-control heavy machinery continued on 16 April.

Nitrogen gas is being injected into the Unit 1 containment vessel to reduce the possibility of hydrogen combustion within the containment vessel. The pressure in this containment vessel has stabilised. The pressure in the RPV is stable.

In Unit 1, fresh water is being continuously injected into the RPV through the feed-water line at an indicated flow rate of 6 m3/h using a temporary electric pump with off-site power. In Units 2 and 3, fresh water is being continuously injected through the fire extinguisher lines at an indicated rate of 7 m3/h using temporary electric pumps with off-site power.

RPV temperatures remain above cold shutdown conditions in all Units, (typically less than 95 °C). In Unit 1 the temperature at the feed water nozzle of the RPV is 180 °C and at the bottom of the RPV is 117 °C. In Unit 2, the temperature at the feed water nozzle of the RPV is 141 °C. In Unit 3 the temperature at the feed water nozzle of the RPV is 91 °C and at the bottom of the RPV is 122 °C.

In accordance with the report of the Nuclear Emergency Response HQs (Prime Minister's Office) from 15 April, thermography temperatures of the Containment Vessel and Spent Fuel Pool in Unit 1 were 33 & deg;C and 36 °C respectively. In Unit 3 the temperatures were 68 °C and 59 °C at the same positions. Also on 15 April, thermography temperature of the Unit 2 reactor building roof was 31 °C

As of 16 April, no white "smoke" was seen to be coming from Unit 1 although white "smoke" was still observed coming from Units 2 and 3. As of 16 April white "smoke" was also visible in Unit 4.

Fresh water injection (around 45 tonnes) to the spent fuel pool was carried out via the spent fuel pool cooling line of Unit 2 and completed by 16 April. Due to the occurrence of an earthquake on 16 April, the motor-driven pump was stopped. The spent fuel pool was confirmed to be filled with water.

In accordance with NISA Release 94, TEPCO took water samples from the spent fuel pool of Unit 4 on 12 April, in order to examine the conditions. The sample was taken by using the arm of the concrete pump vehicle. At the same time, the temperature of water in the spent fuel pool of Unit 4 was measured with a thermistor attached to the arm of the concrete pump vehicle. The activities for I-131, Cs-134 and Cs-137 were 220 Bq/cm3, 88 Bq/cm3 and 93 Bq/cm3 respectively.

There has been no change in the status in Units 5 and 6.

The power supply to the Common Spent Fuel Pool was temporarily interrupted due to a short-circuit on 17 April.

2. Radiation Monitoring

From 15 to 17 April, I-131 was detected in only one prefecture on 15 April; with a reported value of 4.1 Bq/m2. During this period, deposition of Cs-137 was detected in 8 prefectures. The total deposition of Cs-137 in these prefectures on these 3 days ranged from 2.3 Bq/m2 to 66 Bq/m2.

Gamma dose rates are measured daily in all 47 prefectures. The values tend to decrease over time. For Fukushima, on 18 April a dose rate of 1.9 µSv/h was reported. In the Ibaraki prefecture, a gamma dose rate of 0.13 µSv/h was reported; in all other prefectures, reported gamma dose rates were below 0.1 µSv/h.

Dose rates are also reported specifically for the Eastern part of the Fukushima prefecture, for distances beyond 30 km from Fukushima-Daiichi. On 16 April, the values in this area ranged from 0.1 to 25 µSv/h.

In cooperation with local universities, MEXT has set up an additional monitoring programme, for 17 April, measurements of the gamma dose rates were reported for 53 cities in 40 prefectures. In 43 cities, the gamma dose rates were below 0.1 µSv/h. In 9 cities, gamma dose rates ranged from 0.12 to 0.17 µSv/h. In Fukushima City, a value of 0.42 µSv/h was observed.

Only in a few prefectures, I-131 or Cs-137 is detectable in drinking water at very low levels. As of 16 April, one restriction for infants related to I-131 (100 Bq/l) is in place in a small scale water supply in a village of the Fukushima prefecture.

On 15 and 16 April, the IAEA Team made measurements at 44 different locations in the Fukushima area at distances ranging from 20 to 58 km, West from the Fukushima nuclear power plant. At these locations, the dose rates ranged from 0.6 to 37 µSv/h. At the same locations, results of beta-gamma contamination measurements ranged from 0.03 to 2.8 Megabecquerel/m2. The highest values were observed at distances of less than 30 km from the power plant.

On 17 April, the IAEA Team made measurements at 17 different locations in the Fukushima area at distances ranging from 20 to 62 km, North and Northwest from the Fukushima nuclear power plant. At these locations, the dose rates ranged from 0.4 to 3.3 µSv/h. At the same locations, results of beta-gamma contamination measurements ranged from 0.03 to 0.27 Megabecquerel/m2.

Analytical results related to food contamination were reported by the Japanese Ministry of Health, Labour and Welfare on 15 April (34 samples), 16 April (65 samples) and 17 April (51 samples). These reported analytical results covered a total of 150 samples taken from 13 to 16 April. Analytical results for 146 of the 150 samples for various vegetables, spinach and other leafy vegetables, shitake mushrooms, fruit (strawberries), seafood and unprocessed raw milk in nine prefectures (Chiba, Fukushima, Gunma, Hyogo, Ibaraki, Kanagawa, Niigata, Saitama and Yamagata), indicated that I-131, Cs-134 and/or Cs-137 were either not detected or were below the regulation values set by the Japanese authorities. In Fukushima prefecture, three samples of shitake mushrooms taken on 14 April were above the regulation value set by the Japanese authorities for Cs-134 and Cs-137. One sample of shitake mushrooms taken on 14 April was above the regulation values set by the Japanese authorities for I-131 and/or Cs-134 and Cs-137.

On 16 April, the restriction on the distribution of raw unprocessed milk produced in Fukushima was lifted in 25 areas (Fukushima city, Nihonmatsu city, Date city, Motomiya city, Kunimi town, Otama village, Furudono city, Koriyama city, Sukagawa city, Tamura city (excluding former Toji village area), Miharu town, Ono town, Kagamiishi town, Ishikawa town, Asakawa town, Hirata village, Shirakawa city, Yabuki town, Izumisaki village, Nakajima village, Saigo village, Samekawa village, Hanawa town, Yamatsuri town and Iwaki city).

On 17 April, the restriction on the distribution of Kakina and parsley produced throughout Ibaraki prefecture was lifted. The restriction on the distribution of spinach from Ibaraki prefecture was also lifted with the exception of spinach produced in the cities of Kitaibaraki and Takahagi.

3. Marine Monitoring

TEPCO Monitoring Programme

TEPCO is conducting a programme for seawater (surface sampling) at a number of near-shore and off-shore monitoring locations. Following a directive from NISA, on 16 April TEPCO announced they will increase the number of sea sampling points from 10 to 16. A further four points will be added at 3 km from the coast and two points will be added at 8 km from the coast.

On some days, two samples were collected at the same sampling point, a few hours apart and analysed separately.

Until 3 April a general decreasing trend in radioactivity was observed at the sampling points TEPCO 1 to TEPCO 4. After the discharge of contaminated water on 4 April, a temporary increase in radioactivity has been reported. Again since 5 April, general downward in the concentration of radionuclides in sea water for all TEPCO sampling points has been observed.

On the 18 April no new data for TEPCO sampling points have been reported.

MEXT Off-shore Monitoring Programme

The Japanese Ministry of Education, Culture, Sports, Science and Technology (MEXT) initiated the off-shore monitoring program on 23 March and subsequently points 9 and 10 were added to the off-shore sampling scheme. On 4 April, MEXT added two sampling points to the north and west of sampling point 1. These are referred to as points A and B. (See Map 2: MEXT Seawater sampling Locations).

The last results reported on 18 April (sampling date 15 April) showed that Cs-137 and I-131 were detected at MEXT 4, 6 and 8. The highest concentrations were recorded at MEXT 4 (below 200Bq/l for Cs-137 and about 160 Bq/l for I-131). At MEXT 6 and 8 sampling locations both C-s-137 and I-131 were reported at levels below about 40 Bq/l.

Map 2: MEXT Seawater Sampling Locations

MEXT Seawater Sampling Locations

IAEA Briefing on Fukushima Nuclear Accident (15 April 2011, 14:30 UTC)


Presentation:
Summary of Reactor Status

(Note: The next written brief will be available on Monday, 18 April, unless there are any significant developments.)

On Friday, 15 April 2011, the IAEA provided the following information on the current status of nuclear safety in Japan:

1. Current Situation

Overall, the situation at the Fukushima Daiichi nuclear power plant remains very serious but there are early signs of recovery in some functions, such as electrical power and instrumentation.

Changes to Fukushima Daiichi Plant Status

The transfer of contaminated water from the trench of the Unit 2 Turbine Building to the condenser started on 12 April and continued on 13 April until approximately 660 tonnes were transferred.

To minimize the movement of contaminated water to the open sea, temporary boards to stop water (3 steel plates in total) were installed on 13 April on the ocean-side of the Inlet Bar Screen of Unit 2.

Silt fences have also been installed in the inlet canal and in front of the Inlet Bar Screens of Units 1, 2, 3 and 4. On 11 April, a silt screen was installed at the southern end of the inlet canal. The installation in front of the Inlet Bar Screen of Units 3 and 4 was completed on 13 April and for Units 1 and 2 on 14 April.

As of 14 April, white "smoke" was still observed coming from Units 2 and 3. White "smoke" was also observed coming from Unit 4 on 14 April.

On 13 April, Japan's Nuclear and Industrial Safety Agency (NISA) reported that the Tokyo Electric Power Compan (TEPCO) had begun to install a backup line for providing fresh water to the Reactor Pressure Vessels (RPVs) at Units 1, 2, and 3.

In Unit 1, fresh water is being continuously injected into the RPV through the feed-water line at an indicated flow rate of 6 m3/h using a temporary electric pump with off-site power. In Units 2 and 3, fresh water is being continuously injected through the fire extinguisher lines at an indicated rate of 7 m3/h using temporary electric pumps with off-site power.

Nitrogen gas is being injected into the Unit 1 containment vessel to reduce the possibility of hydrogen combustion within the containment vessel. The pressure in this containment vessel has stabilised. The pressure in the RPV is increasing as indicated on one channel of instrumentation. The other channel shows RPV pressure as stable. In Units 2 and 3 Reactor Pressure Vessel and Drywell pressures remain at atmospheric pressure.

RPV temperatures remain above cold shutdown conditions in all Units, (typically less than 95 °C). In Unit 1, the temperature at the feed water nozzle of the RPV is 197 °C and at the bottom of the RPV is 119 °C. In Unit 2, the temperature at the feed water nozzle of the RPV is 150 °C. In Unit 3 the temperature at the feed water nozzle of the RPV is 91 °C and at the bottom of the RPV is 121 °C.

On 14 April, a concrete pump truck, with a capacity of 50t/h, began spraying fresh water to the Unit 3 spent fuel pool. In Unit 4, a sample of the water in the spent fuel pool was collected for analysis.

There has been no change in status in Unit 5 and 6 and the Common Spent Fuel Storage Facility.

2. Radiation Monitoring

On 14 April, depositions of both Iodine-131 and Cesium-137 were detected in 1 and 5 prefectures respectively. For both I-131 and Cs-137, the depositions detected were below 20 Bq/m2 at all stations.

Gamma dose rates are measured daily in all 47 prefectures. The values have tended to decrease over time. For Fukushima, on 14 April a dose rate of 2.0 µSv/h was reported. In the Ibaraki prefecture, a gamma dose rate of 0.14 µSv/h was reported. The gamma dose rates in all other prefectures were below 0.1 µSv/h.

Dose rates are also reported specifically for the Eastern part of the Fukushima prefecture, for distances beyond 30 km from Fukushima Daiichi. On 14 April, the values in this area ranged from 0.1 to 21 µSv/h.

In cooperation with local universities, Japan's Ministry of Education, Culture, Sports, Science and Technology (MEXT)has set up an additional monitoring programme and measurements of the gamma dose rates are made in 54 cities in 40 prefectures. As of 14 April, the gamma dose rates were below 0.1 µSv/h in 45 cities. In 8 cities, gamma dose rates ranged from 0.13 to 0.17 µSv/h. In Fukushima City, a value of 0.42 µSv/h was observed.

Only in a few prefectures, I-131 or Cs-137 is detectable in drinking water at very low levels. As of 12 April, one restriction for infants related to I-131 (100 Bq/l) is in place in a smallscale water supply in a village of the Fukushima prefecture.

On 14 April, an IAEA Team made measurements at 11 different locations in the Fukushima area at distances ranging from 15 to 39 km, South and Southwest from the Fukushima Daiichi nuclear power plant. At these locations, the dose rates ranged from 0.3 to 2.8 µSv/h. At the same locations, results of beta-gamma contamination measurements ranged from 0.16 to 2.5 MBq/ m2. The highest values were observed at distances of less than 23 km from the power plant.

NISA reported on 14 April that among approximately 300 workers at the Fukushima Daiichi plant, 28 have received accumulated doses exceeding 100 mSv in the period related to this emergency. No worker has received a dose above Japan's guidance value of 250 mSv for restricting the exposure of emergency workers.

Analytical results related to food contamination were reported by the Japanese Ministry of Health, Labour and Welfare on 14 April for a total of 50 samples taken from 11th to 14 April. Analytical results for all of the samples of various vegetables, mushrooms, fruits (strawberries), various meats, seafood and unprocessed raw milk in ten prefectures (Chiba, Fukushima, Gunma, Ibaraki, Kanagawa, Nagano, Niigata, Saitama, Tochigi and Yamagata) indicated that I-131, Cs-134 and/or Cs-137 were either not detected or were below the regulation values set by the Japanese authorities.

On 14 April, the Prime Minister of Japan approved the lifting of restrictions on the distribution of kakina in Tochigi prefecture.

3. Marine Monitoring

TEPCO Monitoring Programme

TEPCO is conducting a programme for seawater (surface sampling) at a number of near-shore and off-shore monitoring locations. (See Map 1: TEPCO Seawater Sampling Locations).

On some days, two samples were collected at the same sampling point, a few hours apart and analysed separately.

Until 3 April a general decreasing trend in radioactivity was observed at the sampling points TEPCO 1 to TEPCO 4. After the discharge of contaminated water on 4 April, a temporary increase in radioactivity was reported. Since 5 April, a general downward trend in the concentration of radionuclides in sea water for all TEPCO sampling points has been observed.

On 15 April, new data for TEPCO 1 - 4 sampling points have been reported. At all four locations, the concentration of both I-131 and Cs-137 measured on 12 April was below 2kBq/l.

For TEPCO 5 - 10 no new data have been reported.

MEXT Off-shore Monitoring Programme

MEXT initiated the off-shore monitoring program on 23 March and subsequently points 9 and 10 were added to the off-shore sampling scheme. On 4 April, MEXT added two sampling points to the north and west of sampling point 1. These are referred to as points A and B. (See Map 2: MEXT Seawater Sampling Locations).

The most recent results reported on 11 April showed that Cs-137 was only detected at MEXT 4 (below 100Bq/l). The highest concentration of I-131 (about 90 Bq/l) was also recorded at MEXT 4. For other sampling locations I-131 was reported at levels below about 15 Bq/l.

On 15 April, no new data from any MEXT sampling points have been reported.

Map 1: TEPCO Seawater Sampling Locations:

TEPCO Seawater Sampling Locations

Map 2: MEXT Seawater Sampling Locations:

MEXT Seawater Sampling Locations

4. IAEA Activities

The 141st Session of the FAO Council was briefed by representatives of the Joint FAO/IAEA Division on the nuclear emergency in Japan on Friday, 15 April, at the FAO Headquarters in Rome, Italy. The briefing included a general background summary of the emergency, the current situation in Japan, FAO/IAEA/WHO responses and actions taken to date, and future challenges. The Member States expressed their appreciation for the IAEA/FAO/WHO inter-agency collaboration and coordination during the Japanese nuclear emergency and called for strengthening cooperation in future remediation actions.

IAEA Briefing on Fukushima Nuclear Accident (14 April 2011, 15:30 UTC)


Presentation:
Summary of Reactor Status

On Thursday, 14 April 2011, the IAEA provided the following information on the current status of nuclear safety in Japan:

1. Current Situation

Overall, the situation at the Fukushima Daiichi plant remains very serious but there are early signs of recovery in some functions such as electrical power and instrumentation.

Earthquake of 13 April

The NISA Press Release reported that an earthquake occurred at Hamadori in Fukushima prefecture on 13 April, at 01:07 UTC. The earthquake had a moment magnitude of M 5.4 and was at a depth of 24.7 km, as reported by the IAEA International Seismic Safety Centre. The distances from the earthquake's epicenter to Fukushima Daini and Fukushima Daiichi nuclear power plant were 67 and 75 km respectively. No unusual events have been reported at the near sites (Onagawa, Fukushima Daiichi, Fukushima Daini and Tokai).

Changes to Fukushima Daiichi Plant Status

Freshwater injection is confirmed to continue for Units 1 to 3. The transfer of contaminated water from Unit 2 turbine building to the condenser was started (12 April) and suspended (13 April) to check for any leakage. Temperature at the Unit 1 outlet nozzle shows a decreasing trend continuously for several days now.

To minimize migration of contaminated water to the open sea, on the ocean-side of the Inlet Bar Screen of Unit 2, the two temporary steel plates (3 plates in total) were installed to stop water from leaking out of the inlet bay (around 08:30 untill 10:00, 13 April). In addition, a silt fence to prevent the spread of the contaminated water was installed in front of the Screen of Units 3 and 4. (13:50 UTC, 13 April).

In Unit 1 fresh water is being continuously injected into the RPV through the feed-water line at an indicated flow rate of 6 m3/h using a temporary electric pump with off-site power. In Units 2 and 3 fresh water is being continuously injected through the fire extinguisher lines at an indicated rate of 7 m3/h using temporary electric pumps with off-site power.

Nitrogen gas is being injected into the Unit 1 containment vessel to reduce the possibility of hydrogen combustion within the containment vessel. The pressure in this containment vessel has stabilised. The pressure in the RPV is increasing as indicated on one channel of instrumentation. The other channel shows RPV pressure as stable. In Units 2 and 3 Reactor Pressure Vessel and Drywell pressures remain at atmospheric pressure.

RPV temperatures remain above cold shutdown conditions in all Units, (typically less than 95 °C). In Unit 1 the temperature at the feed water nozzle of the RPV is 206 °C and at the bottom of the RPV is 119 °C. In Unit 2 the temperature at the feed water nozzle of the RPV is 167 °C. In Unit 3 the temperature at the feed water nozzle of the RPV is 92 °C and at the bottom of the RPV is 119 °C.

On 12 April in Units 3 and 4, fresh water (35 T and 195 T respectively) was sprayed over the Spent Fuel Pools using a Concrete Pump Truck. A sample of the water in the spent fuel pool was collected for analysis.

There has been no change in status in Unit 5 and 6 and the Common Spent Fuel Storage Facility.

2. Radiation Monitoring

On 13 April, deposition of both I-131 and Cs-137 was detected in 2 and 5 prefectures respectively. For both, I-131 and Cs-137, the depositions detected were below 20 Bq/m2 at all stations.

Gamma dose rates are measured daily in all 47 prefectures. The values tend to decrease over time. For Fukushima, on 13 April a dose rate of 2.0 µSv/h was reported. In the Ibaraki prefecture, a gamma dose rate of 0.14 µSv/h was reported. The gamma dose rates in all other prefectures were below 0.1 µSv/h.

Dose rates are also reported specifically for the Eastern part of the Fukushima prefecture, for distances beyond 30 km from Fukushima-Daiichi. On 13 April, the values in this area ranged from 0.2 to 26 µSv/h.

In addition to the 7 measurements referred to in yesterday's brief, (note- these measurements were made at distances of 25 km and 33 km not 32 km and 62 km as reported), 13 more measurements were made on 12 April at distances of 25 to 33 km, West and Northwest from the Fukushima Nuclear Power Plant by the IAEA team. At these locations, the dose rates ranged from 0.5 to 16.5 µSv/h. At the same locations, results of beta-gamma contamination measurements ranged from 0.05 to 2.1 Megabecquerel/m2.

On 13 April, the IAEA Team made measurements at 7 different locations in the Fukushima area at distances ranging from 32 to 62 km, North and Northwest from the Fukushima Daiichi nuclear power plant. At these locations, the dose rates ranged from 0.35 to 2.6 µSv/h. At the same locations, results of beta-gamma contamination measurements ranged from 0.35 to 2.6 Megabecquerel/m2.

Analytical results related to food contamination were reported by the Japanese Ministry of Health, Labour and Welfare on 13 April that covered a total of 98 samples taken on 4 and 11 to 13 April. Analytical results for 76 of the samples of various vegetables, pork, seafood and unprocessed raw milk in nine prefectures (Chiba, Fukushima, Gunma, Ibaraki, Kanagawa, Miyagi, Niigata, Saitama and Yamagata) indicated that I-131, Cs-134 and/or Cs-137 were either not detected or were below the regulation values set by the Japanese authorities. In Fukushima prefecture on 11 April, twenty samples of various vegetables were above the regulation values set by the Japanese authorities for Cs-134/Cs-137, and one sample of seafood (sand lance) and one sample of spinach were above the regulation values set by the Japanese authorities for both I-131 and Cs-134/Cs-137.

3. Marine Monitoring

TEPCO Monitoring Programme

TEPCO is conducting a programme for seawater (surface sampling) at a number of near-shore and off-shore monitoring locations. (See Map 1: TEPCO Seawater Sampling Locations).

On some days, two samples were collected at the same sampling point, a few hours apart and analysed separately.

Until 3 April a general decreasing trend in radioactivity was observed at the sampling points TEPCO 1 to TEPCO 4. After the discharge of contaminated water on 4 April, a temporary increase in radioactivity has been reported.

On 11 April decreasing trends for both I-131 and Cs-137 concentrations of two orders of magnitude from near-shore (less than 10 kBq/l) to 15 km off-shore (0.1-0.02 kBq/l) were observed.

On 14 April no new data for TEPCO 1 - 10 sampling points have been reported.

MEXT Off-shore Monitoring Programme

Japanese Ministry of Education, Culture, Sports, Science and Technology (MEXT) initiated the off-shore monitoring program on 23 March and subsequently points 9 and 10 were added to the off-shore sampling scheme. On 4 April, MEXT added two sampling points to the north and west of sampling point 1. These are referred to as points A and B. (See Map 2: MEXT Seawater Sampling Locations).

On 11 April Cs-137 was only detected at MEXT 4 at a concentration level of about 70 Bq/l. The highest concentration of I-131 (about 90 Bq/l) was also recorded at MEXT4. For other sampling locations I-131 was reported at levels below about 15 Bq/l.

0n 14 April no new data for all MEXT sampling points have been reported.

Map 1: TEPCO Seawater Sampling Locations:

TEPCO Seawater Sampling Locations



Map 2: MEXT Seawater Sampling Locations:

TEPCO Seawater Sampling Locations



4. IAEA Activities

The 141st Session of the FAO Council will be briefed by representatives of the Joint FAO/IAEA Division on the nuclear emergency in Japan on Friday, 15 April, at FAO Headquarters in Rome, Italy. The briefing will include a general background summary of the emergency, the current situation in Japan, FAO/IAEA/WHO responses and actions taken to date, and future challenges.

IAEA Briefing on Fukushima Nuclear Accident (13 April 2011, 14:30 UTC)


Presentation:
Summary of Reactor Status

On Wednesday, 13 April 2011, the IAEA provided the following information on the current status of nuclear safety in Japan:

1. Current Situation

Overall, the situation at the Fukushima Daiichi plant remains very serious but there are early signs of recovery in some functions such as electrical power and instrumentation.

There have been no changes concerning the provisional INES Level 7 rating and protective measures as reported in yesterday's brief.

Earthquakes of 11 and 12 April

The IEC received information from the IAEA International Seismic Safety Center on the following recent earthquakes (equal or higher than magnitude Mw = 6.0) which occurred in the time interval from 23:08 UTC on 11 April to 05:07 UTC on 12 April:

i) At 23:08 UTC, 11 April, an earthquake with a magnitude of 6.2 occurred offshore of the East Coast of Honshu, Japan, at a depth of 13.1 km. Distances from the epicentre of the earthquake to nuclear power plant sites were: 188 km to Tokai, 217 km to Fukushima Daini, 229 km to Fukushima Daiichi, 236 km to Hamaoka and 285 km to Kashiwazaki-Kariwa.

ii) At 05:07 UTC, 12 April, an earthquake with a magnitude of 6.0 occurred inland east of Honshu, Japan, at a depth of 10.6 km. Distances from the epicentre of the earthquake to nuclear power plant sites were: 46 km to Fukushima Daini, 53 km to Fukushima Daiichi, 72 km to Tokai, 165 km to Onagawa and 179 km to Kashiwazaki-Kariwa.

The NISA Press Release regarding the earthquake which occurred on 12 April, states that there was no effect on the following nuclear power plant sites: Fukushima Daiichi, Fukushima Daini, Tokai Daini, Onagawa. Other nuclear related facilities (Mitusubishi Nuclear Fuel, Nuclear Fuel Industries, Ltd., JAEA Tokai and its recycling plant) in the Tokai area were reported to be safe by their respective operators.

Changes to Fukushima Daiichi Plant Status

On 11 April, a fire broke out in the housing outlet structure for cooling water for Units 1 to 4. The fire was extinguished manually. No consequences were identified in terms of release of radioactive material, cooling of the plants, or values recorded by radiation monitoring posts.

In Unit 1 fresh water is being continuously injected into the RPV through the feed-water line at an indicated flow rate of 6 m3/h using a temporary electric pump with off-site power. In Units 2 and 3 fresh water is being continuously injected through the fire extinguisher lines at an indicated rate of 7 m3/h using temporary electric pumps with off-site power.

Nitrogen gas is being injected into the Unit 1 containment vessel to reduce the possibility of hydrogen combustion within the containment vessel. The pressure in this containment vessel has stabilised. The pressure in the RPV is increasing as indicated on one channel of instrumentation. The other channel shows RPV pressure as stable.

In Units 2 and 3 Reactor Pressure Vessel and Drywell pressures remain at atmospheric pressure.

RPV temperatures remain above cold shutdown conditions in all Units, (typically less than 95 °C). In Unit 1 temperature at the feed water nozzle of the RPV is 206 °C and at the bottom of the RPV is 119 °C. In Unit 2 the temperature at the feed water nozzle of the RPV is 165 °C. The temperature at the bottom of RPV was reported as 208 °C (this measurement has been available since 12 April). In Unit 3 the temperature at the feed water nozzle of the RPV is 99 °C and at the bottom of the RPV is 116 °C.

There has been no change in status in Units 4, 5 and 6 and the Common Spent Fuel Storage Facility.

2. Radiation Monitoring

On 12 April, deposition of both iodine-131 and cesium-137 was detected in 7 and 6 prefectures respectively. The values reported for iodine-131 ranged from 1.6 to 460 Bq/m2 and for cesium-137 from 31 to 700 Bq/m2. The highest deposition was observed in the Ibaraki prefecture.

Gamma dose rates are measured daily in all 47 prefectures, the values tend to decrease. For Fukushima, on 12 April a dose rate of 2.1 µSv/h, for the Ibaraki prefecture a gamma dose rate of 0.14 µSv/h was reported. The gamma dose rates in all other prefectures were below 0.1 µSv/h.

Only in a few prefectures, iodine-131 or cesium-137 is detectable in drinking water at very low levels. As of 12 April, a restriction for infants related to iodine-131 (100 Bq/l) is in place as a precautionary in a small scale water supply in one village of the Fukushima prefecture.

MEXT reported on measurements of strontium-89 (half-life: 50.5 days) and strontium-90(half-life: 28.8 years) in three samples taken in one village in the Fukushima prefecture on 16 March. The activities in soil for Sr-89 ranged from 13 and 260 Bq/kg and for Sr-90 between 3.3 and 32 Bq/kg. Sr-90 was also distributed globally during nuclear weapons' testing in the atmosphere, typical global levels of Sr-90 in surface soils are in the order of one to a few becquerel per kg. Strontium was also measured in plant samples in four others villages, with values ranging from 12 to 61 Bq/kg for Sr-89 and 1.8 to 5.9 Bq/kg for Sr-90.

On 12 April, the IAEA Team made measurements at 7 different locations in the Fukushima area at distances of 32 to 62 km, North and Northwest from the Fukushima nuclear power plant. At these locations, the dose rates ranged from 0.6 to 1.6 µSv/h. At the same locations, results of beta-gamma contamination measurements ranged from 0.6 to 1.7 Megabecquerel/m2.

NISA reported on 12 April that the three workers who had previously been exposed to high dose rates while working in the turbine building of Unit 3 have undergone further medical checks. No negative outcomes were identified. In the case of the two workers who received doses of a few Sievert to their legs as a result of walking in contaminated water, medical tests showed no evidence of either skin burns or erythema.

Analytical results related to food contamination were reported by the Japanese Ministry of Health, Labour and Welfare on 12 April that covered a total of 55 samples taken on 8 and 10 to 12 April. Analytical results for 53 of the samples of various vegetables, fruit (strawberries), seafood and unprocessed raw milk in eight prefectures (Chiba, Fukushima, Gunma, Ibaraki, Kanagawa, Niigata, Saitama and Yamagata) indicated that I-131, Cs-134 and/or Cs-137 were either not detected or were below the regulation values set by the Japanese authorities. In Ibaraki prefecture for samples taken on 11 April, one sample of seafood (sand lance) was above the regulation values set by the Japanese authorities for I-131 and one sample of spinach was above the regulation values set by the Japanese authorities for Cs-134/Cs-137.

On 13 April, the Prime Minister of Japan requested the Governor of Fukushima prefecture to restrict the consumption of shiitake mushrooms (grown on logs in open fields only) produced at Iitate-village until further notice. Instructions were also issued to restrict the distribution of shiitake mushrooms (grown on logs in open fields only) produced in the cities of Date, Soma, Minamisoma, Tamura and Iwaki; the towns of Shinchi, Kawamata, Namie, Futaba, Ookuma, Tomioka, Naraha and Hirono; and the villages of Iitate, Katsurao and Kawauchi until further notice.

3. Marine Monitoring

TEPCO Monitoring Programme

TEPCO is conducting a programme for seawater (surface sampling) at a number of near-shore and off-shore monitoring locations. (See Map 1: TEPCO Seawater Sampling Locations).

On same days, two samples were collected at the same sampling point, a few hours apart and analysed separately.

Until 3 April a general decreasing trend was observed at the sampling points TEPCO 1 to TEPCO 4. After the discharge of contaminated water on 4 April, a temporary increase has been reported.

On 13 April new data for samples collected on 11 April at TEPCO 1 - 10 sampling points have been reported. As for the near-shore stations TEPCO 1, 3 and 4 levels of I-131 and Cs-137 below 1.5 kBq/l have been reported. At TEPCO 2, for both I-131 and Cs-137 concentrations of about 7 kBq/l were measured.

As for the six TEPCO stations 15 km offshore, at TEPCO 5 - 6 - 10 the concentration of I-131 was below 0.3 kBq/l and that of Cs-137 below 0.2 kBq/l. At TEPCO 7 and 8, I-131 and Cs-137 below 0.05 kBq/l below 0.02 kBq/l were measured. At TEPCO 9 concentrations of about 1 kBq/l of both I-131 and Cs-137 were recorded.

MEXT Off-shore Monitoring Programme

MEXT initiated the off-shore monitoring program on 23 March and subsequently points 9 and 10 were added to the off-shore sampling scheme. On 4 April, MEXT added two sampling points to the north and west of sampling point 1. These are referred to as points A and B. (See Map 2: MEXT Seawater Sampling Locations).

On 13 April new data for samples collected on 11 April at MEXT 2, 4, 6, 8, 10 an B sampling points have been reported.

Cs-137 was only detected at MEXT 4 at a concentration level of about 70 Bq/l.

I-131 concentration of about 90 Bq/l was measured at Station MEXT 4. At MEXT 6, 8, 10 and B, I-131 below about 15 Bq/l was reported.

Map 1: TEPCO Seawater Sampling Locations:

TEPCO Seawater Sampling Locations



Map 2: MEXT Seawater Sampling Locations:

TEPCO Seawater Sampling Locations



4. IAEA activities

No new activities to report.

IAEA Briefing on Fukushima Nuclear Accident (12 April 2011, 14:30 UTC)


Presentations:
Summary of Reactor Status
Fukushima Radiological Monitoring and Consequences
Fukushima Marine Environment Monitoring
International Nuclear and Radiological Event Scale (INES)
Watch Video

On Tuesday, 12 April 2011, the IAEA provided the following information on the current status of nuclear safety in Japan:

1. Current Situation

Overall, the situation at the Fukushima Daiichi plant remains very serious, but there are early signs of recovery in some functions such as electrical power and instrumentation.

Provisional INES Level 7 Rating

The International Atomic Energy Agency (IAEA) can confirm that the Nuclear and Industrial Safety Agency (NISA) has submitted a provisional International Nuclear and Radiological Event Scale (INES) Level 7 rating for the accident at the Fukushima Daiichi nuclear power plant. This new provisional rating considers the accidents that occurred at Units 1, 2 and 3 as a single event on INES and uses estimated total release to the atmosphere as a justification. Previously, separate provisional INES Level 5 ratings had been applied for Units 1, 2 and 3.

Japanese authorities notified the IAEA in advance of the public announcement and the formal submission of the new provisional rating.

The provisional rating was determined by NISA after it received the results of the analysis conducted by the Japan Nuclear Energy Safety Organization (JNES). NISA then applied the INES assessment methodology to calculate the total estimated release in terms of radiological equivalence to I-131. Based on this provisional assessment, NISA concluded that the accident would be provisionally rated INES Level 7 as per the definition below, taken from the INES User's Manual, 2008 Edition [pdf]:

Level 7

"An event resulting in an environmental release corresponding to a quantity of radioactivity radiologically equivalent to a release to the atmosphere of more than several tens of thousands of terabequerels of I-131."

NISA estimates that the release of radioactive material to the atmosphere is approximately 10% of the Chernobyl accident, which is the only other accident to have an INES Level 7 rating.

Protective Measures

"On 11 April the Government of Japan announced that they had concluded to establish 'Planned Evacuation Areas' and 'Evacuation prepared Area' in the areas beyond the 20km radius from the Fukushima Daiichi nuclear power plant. The review was conducted because the Government consider the safety of residents its first priority.

The Government of Japan considered the standards recommended by the International Commission on Radiological Protection (ICRP) and the International Atomic Energy Agency (IAEA) as part of the review.

About the 'Planned Evacuation Areas', the Japanese authorities have found that the areas beyond 20 km radius could be exposed to over 20mSv during the course of the next one year, approximately until next March. Therefore the Government of Japan will be consulting with the local communities in terms of planned evacuations, ant at this juncture they are hoping that this planned evacuation will be carried out during the next month to come. The Planned Evacuation Areas that have been newly designated for evacuation include Kutsurao village, Namie town, Iitate village, a part of Kawamata town and a part of Minami Souma City.

The Government also defined a second new area called the 'Evacuation Prepared Area'. This area includes the area previously defined as the 'Indoor Evacuation Area' between 20 and 30 km from Fukushima Daiichi, but excludes those areas designated above as 'Planned Evacuation Areas'.

Within the 'Evacuation Prepared Area' people living in this area should be prepared for indoor evacuation or evacuation (outside of this area) in case of emergency. Voluntary evacuation is recommended within this area. Children, pregnant women, people who require nursing care and those who are hospitalized should not enter this area. Kindergartens, pre-schools, elementary schools, junior-high schools and high school will be closed within this area."

Earthquake of 11 April

The IAEA confirms that an earthquake occurred in Japan at 08:16 UTC, 11 April.

The IAEA International Seismic Safety Centre rated it as a 6.6 magnitude, revised from an initial 7.1 magnitude. The epicenter of the earthquake was in Fukushima Prefecture, 68 km from the Daiichi nuclear power plant. The epicenter was inland at a depth of 13.1 km.

The IAEA contacted NISA who confirmed the following regarding the status of the Fukushima Daiichi nuclear power plant:

  • No changes were observed on the readings at the on-site radiation monitoring posts;
  • Workers were temporarily evacuated to the seismic evacuation shelter;
  • Off-site power was lost and water injection pumps for Units 1, 2 and 3 stopped but were restarted 50 minutes after the earthquake; and
  • The injection of nitrogen into Unit 1 stopped and resumed later.

Changes to Fukushima Daiichi Plant Status

In Unit 1 fresh water is being continuously injected into the RPV through the feed-water line at an indicated flow rate of 6 m3/h using a temporary electric pump with off-site power. In Units 2 and 3 fresh water is being continuously injected through the fire extinguisher lines at an indicated rate of 7 m3/h using temporary electric pumps with off-site power.

Nitrogen gas is being injected into the Unit 1 containment vessel to reduce the possibility of hydrogen combustion within the containment vessel. The pressure in this containment vessel is increasing due to the addition of nitrogen. The pressure in the RPV is increasing as indicated on both channels of instrumentation. In Units 2 and 3 Reactor Pressure Vessel and Drywell pressures remain at atmospheric pressure.

RPV temperatures remain above cold shutdown conditions in all Units, (typically less than 95 °C). In Unit 1 temperature at the feed water nozzle of the RPV is 221 °C and at the bottom of the RPV is 120 °C. In Unit 2 the temperature at the feed water nozzle of the RPV is 155 °C. The temperature at the bottom of the RPV was not reported. In Unit 3 the temperature at the feed water nozzle of the RPV is 97 °C and at the bottom of the RPV is 111 °C.

There has been no change in status in Units 4, 5 and 6 and the Common Spent Fuel Storage Facility.

2. Radiation Monitoring

On 11 April, deposition of both iodine-131 and cesium-137 was detected in 6 and 8 prefectures respectively. The values reported for iodine-131 ranged from 2.1 to 35 Bq/m2 and for cesium-137 from 5.2 to 41 Bq/m2.

Gamma dose rates are measured daily in all 47 prefectures, the values tend to decrease. For Fukushima, on 11 April a dose rate of 2.1 µSv/h, for the Ibaraki prefecture a gamma dose rate of 0.15 µSv/h was reported. The gamma dose rates in all other prefectures were below 0.1 µSv/h.

Dose rates are also reported specifically for the Eastern part of the Fukushima prefecture, for distances of more than 30 km to Fukushima-Daiichi. On 11 April, the values in this area ranged from 0.2 to 25 µSv/h.

In an additional MEXT monitoring programme, on 11 April measurements were reported for 25 cities in 13 prefectures. In Fukushima City, a value of 0.42 µSv/h was observed. In all other cities, gamma dose rates ranged from 0.04 to 0.13 µSv/h. Typical normal background levels are in the range of 0.05 to 0.10 µSv/h.

On 11 April, the IAEA Team made measurements at 9 different locations in the Fukushima area at distances of 30 to 58 km, West to Northwest from the Fukushima nuclear power plant. At these locations, the dose rates ranged from 0.1 to 2.2 µSv/h. At the same locations, results of beta-gamma contamination measurements ranged from 0.01 to 0.28 Megabecquerel/m2.

Analytical results related to food contamination were reported by the Japanese Ministry of Health, Labour and Welfare on 11 April, and covered a total of 21 samples taken on 8 April and 10 to 11 April. Analytical results for all of the samples of various vegetables, spinach and other leafy vegetables, fruit (strawberries), various meats (chicken, beef and pork), seafood and unprocessed raw milk in eight prefectures (Fukushima, Gunma, Hyogo, Ibaraki, Miyagi, Niigata, Saitama and Yamagata) indicated that I-131, Cs-134 and/or Cs-137 were either not detected or were below the regulation values set by the Japanese authorities.

3. Marine Monitoring

TEPCO Monitoring Programme

TEPCO is conducting a programme for seawater (surface sampling) at a number of near-shore and off-shore monitoring locations.

Until 3 April a general decreasing trend was observed at the sampling points TEPCO 1 to TEPCO 4. After the discharge of contaminated water on 4 April, a temporary increase has been reported.

On 12 April no new data for TEPCO 1 - 10 sampling points have been reported.

MEXT Off-shore Monitoring Programme

As reported in the brief of 8 April MEXT initiated the off-shore monitoring program on 23 March and subsequently points 9 and 10 were added to the off-shore sampling scheme. On 4 April, MEXT added two sampling points to the north and west of sampling point 1. These are referred to as points A and B.

0n 12 April no new data for all MEXT sampling points have been reported.

4. IAEA Activities

In addition to countries that have already been identified in previous briefs, the Philippines and the Republic of Korea have also provided monitoring data and/or links to their websites.

The team of three Agency experts in BWR technology is due back in Vienna today.

Fukushima Nuclear Accident Update (12 April 2011, 04:45 UTC)


The Japanese Nuclear and Industrial Safety Agency (NISA) today issued a new provisional rating for the accident at the Fukushima Daiichi nuclear power plant on the IAEA International Nuclear and Radiological Event Scale (INES).

The nuclear accident at Fukushima Daiichi is now rated as a level 7 "Major Accident" on INES. Level 7 is the most serious level on INES and is used to describe an event comprised of "A major release of radioactive material with widespread health and environmental effects requiring implementation of planned and extended countermeasures". Japanese authorities notified the IAEA in advance of the public announcement and the formal submission of the new provisional rating.

The new provisional rating considers the accidents that occurred at Units 1, 2 and 3 as a single event on INES. Previously, separate INES Level 5 ratings had been applied for Units 1, 2 and 3. The provisional INES Level 3 rating assigned for Unit 4 still applies.

The re-evaluation of the Fukushima Daiichi provisional INES rating resulted from an estimate of the total amount of radioactivity released to the environment from the nuclear plant. NISA estimates that the amount of radioactive material released to the atmosphere is approximately 10% of the 1986 Chernobyl accident, which is the only other nuclear accident to have been rated a Level 7 event.

Earlier ratings of the nuclear accident at Fukushima Daiichi were assessed as follows:

On 18 March, Japanese authorities rated the core damage at the Fukushima Daiichi 1, 2 and 3 reactor Units caused by loss of all cooling function to have been at Level 5 on the INES scale. They further assessed that the loss of cooling and water supplying functions in the spent fuel pool of the Unit 4 reactor to have been rated at Level 3.

Japanese authorities may revise the INES rating at the Fukushima Daiichi nuclear power plant as further information becomes available.

INES is used to promptly and consistently communicate to the public the safety significance of events associated with sources of radiation. The scale runs from 0 (deviation) to 7 (major accident).

Further information on the INES scale: http://www-ns.iaea.org/tech-areas/emergency/ines.asp.

Further details regarding this development can be found in the NISA Press Release [pdf].

IAEA Briefing on Fukushima Nuclear Accident (11 April 2011, 13:00 UTC)


Presentation:
Summary of Reactor Status

On Monday, 11 April 2011, the IAEA provided the following information on the current status of nuclear safety in Japan:

1. Current Situation

Earthquake of 7 April

External power has been restored at all sites affected by the 7 April earthquake.

Earthquake of 11 April

The IAEA confirms that an earthquake occurred in Japan at 08:16 UTC, 11 April. The IAEA International Seismic Safety Centre (ISSC) has rated it as a 6.6 magnitude, revised from an initial 7.1 magnitude. The epicenter of the earthquake is 68 km from Daichi, 60 km from Daini, 61 km from Tokai, 173 km from Kashiwazaki-Kariwa and 179 km from Onagawa power plants. The epicenter was in land (37.01 N/ 140.48 E) at a depth of 13.1 km. The IAEA has been in contact with NISA and can confirm the following. Based on a report by TEPCO, NISA confirms at the Fukushima Daiichi nuclear power plant. No changes have been observed on the readings at the on-site radiation monitoring posts. Workers have been evacuated to the seismic evacuation shelter. Off-site power was lost and water injection pumps for Units 1, 2 and 3 stopped. NISA confirmed later that off-site power was restored and water injection resumed 50 minutes after the earthquake.

Changes to Fukushima Daiichi Plant Status

Overall, the situation at the Fukushima Daiichi plant remains very serious but there are early signs of recovery in some functions such as electrical power and instrumentation.

In Units 1, 2 and 3, 60 000 T of contaminated water need to be removed from the turbine buildings and trenches. This water will be transferred to the condensers of each unit and the Radioactive Waste Treatment facility. In addition, temporary storage tanks have been ordered to provide additional capacity for the water and will be located adjacent to the Radioactive Waste Treatment facility. At Unit 1 and 2 water transfer from the condenser to the condensate storage tank was completed on 10 April.

In order to make room for higher contaminated water from the turbine buildings and trenches, 1 343 T of low level contaminated water from Units 5 and 6 sub-drain pit were released to the sea from 4 to 9 April. In addition, 9 070 T of low-level contaminated water was discharged from the Central Radioactive Waste Disposal Facility to the south discharge point.

Nitrogen gas is being injected into the Unit 1 containment vessel to reduce the possibility of hydrogen combustion within the containment vessel. The pressure in this containment vessel is increasing due to the addition of nitrogen.

Since 6 April, TEPCO has been moving debris from Units 1 to 4 to a common storage area on-site using remote controlled heavy equipment.

On 10 April additional anti-scattering agent was sprayed in an area of about 550 m2 on the mountain-side of the Common Spent Fuel Pool to prevent the radioactive materials on the ground from being scattered.

In Unit 1 fresh water is being continuously injected into the RPV through the feed-water line at an indicated flow rate of 6 m3/h using a temporary electric pump with off-site power. In Units 2 and 3 fresh water is being continuously injected through the fire extinguisher lines at an indicated rate of 7 m3/h using temporary electric pumps with off-site power.

In Unit 1 the pressure in the RPV is increasing, as indicated on both channels of instrumentation. In Units 2 and 3 Reactor Pressure Vessel and Drywell pressures remain at atmospheric pressure.

RPV temperatures remain above cold shutdown conditions in all Units, (typically less than 95 °C). In Unit 1 temperature at the feed water nozzle of the RPV is 228 °C and at the bottom of the RPV is 121 °C. In Unit 2 the temperature at the feed water nozzle of the RPV is 149 °C. The temperature at the bottom of the RPV was not reported. In Unit 3 the temperature at the feed water nozzle of the RPV is 92 °C and at the bottom of the RPV is 111 °C.

An additional 60 T of fresh water was injected via the Spent Fuel Cooling System line to the spent fuel pool in Unit 2 by a temporary pump on 10 April.

There has been no change in status in Units 4, 5 and 6.

2. Radiation Monitoring

On 10 April, deposition of both iodine-131 and cesium-137 was detected in 7 and 6 prefectures respectively. The values reported for iodine-131 ranged from 6.3 to 920 Bq/m2 and for cesium-137 from 7.9 to 800 Bq/m2. The highest deposition was reported for both, iodine-131 and cesium-137, in the prefecture of Ibaraki. /p>

Gamma dose rates are measured daily in all 47 prefectures, the values tend to decrease. For Fukushima, on 10 April a dose rate of 2.2 µSv/h, for the Ibaraki prefecture a gamma dose rate of 0.15 µSv/h was reported. The gamma dose rates in all other prefectures were below 0.1 µSv/h.

Dose rates are also reported specifically for the Eastern part of the Fukushima prefecture, for distances of more than 30 km to Fukushima-Daiichi. On 10 April, the values in this area ranged from 0.2 to 25 µSv/h.

MEXT has set up an additional monitoring programme, in cooperation with local universities, measurements are made in 26 cities in 13 prefectures. As of 10 April, in 19 cities, the gamma dose rates were below 0.1 µSv/h. In 6 cities, gamma dose rates ranged from 0.13 to 0.17 µSv/h. In Fukushima City, a value of 0.42 µSv/h was observed. Typical normal background levels are in the range of 0.05 to 0.10 µSv/h.

Only in a few prefectures, iodine-131 or cesium-137 is detectable in drinking water at very low levels. As of 10 April, a restriction for infants related to iodine-131 (100 Bq/l) is in place as a precautionary measure in only one village of the Fukushima prefecture.

On 10 April, the IAEA Team made measurements at 7 different locations in the Fukushima area at distances of 23 to 39 km, South and Southwest from the Fukushima nuclear power plant. At these locations, the dose rates ranged from 0.4 to 1.6 µSv/h. At the same locations, results of beta-gamma contamination measurements ranged from 0.01 to 0.18 Megabecquerel/m2. The highest beta-gamma contaminations have been determined at distances of less than 30 km from Fukushima-Daiichi.

Analytical results related to food contamination, reported by the Japanese Ministry of Health, Labour and Welfare from 8 to 10 April covered a total of 157 samples taken from 6 to 10 April. Analytical results for 153 of the 157 samples for various vegetables, spinach and other leafy vegetables, shitake mushrooms, fruit (strawberries), pork, seafood and unprocessed raw milk in eight prefectures (Chiba, Fukushima, Gunma, Ibaraki, Kanagawa, Nagano, Niigata and Saitama), indicated that I-131, Cs-134 and/or Cs-137 were either not detected or were below the regulation values set by the Japanese authorities. In Fukushima prefecture, one sample of seafood (sand lance) taken on 7 April was above the regulation values set by the Japanese authorities for I-131 and three samples of shiitake mushrooms taken on 8 April were above the regulation values set by the Japanese authorities for I-131 and/or Cs-134 and Cs-137

3. Marine Monitoring

TEPCO Monitoring Programme

As reported in the brief of 8 April TEPCO is conducting a programme for seawater (surface sampling) at a number of near-shore and off-shore monitoring locations as illustrated in Map 1.

Map 1: TEPCO Seawater Sampling Locations:

TEPCO Seawater Sampling Locations

Until 3 April a general decreasing trend was observed at the sampling points TEPCO1 to TEPCO4. After the discharge of contaminated water on 4 April, a temporary increase has been reported.

On 11 April new data (8 April sampling day) for TEPCO 1 - 4 sampling points have been reported. At the near-shore sampling point TEPCO 1 an increase from 2,2 kBq/l (7 April) to 19 kBq/l for I-131 and from 1.7 kBq/l (7 April) to 12 kBq/l for Cs-137 has been reported. As for TEPCO 3 and TEPCO 4 a further decrease as respect to the results for the sampling day, 7 April, in the concentration of I-131 and Cs-137 has been reported. At the sampling point TEPCO 2 a decrease in the concentration of I-131 to about 50 kBq/l) and Cs-137 to about 34 kBq/l as respect to the results obtained on 7 April was observed.

For the six sampling points TEPCO 5 to TEPCO 10 since 7 April no new data have been reported. The data since 7 April have been summarized in the previous brief of 10 April.

MEXT Off-shore Monitoring Programme

As reported in the brief of 8 April MEXT initiated the off-shore monitoring program on 23 March and subsequently points 9 and 10 were added to the off-shore sampling scheme. On 4 April, MEXT added two sampling points to the north and west of sampling point 1. These are referred to as points A and B on the map below.

Map 2: MEXT Seawater Sampling Locations:

MEXT Seawater Sampling Locations

0n 11 April new data have been reported for MEXT 1, 3, 5, 7 and 9 for 9 April sampling day.

At MEXT 1 both I-131 and Cs-137 were no longer detectable. At MEXT 3 an increase of the level of both I-131 and Cs-137 was recorded. At MEXT 5 the level of I-131 decreased and Cs-137 was not detected. At MEXT 7 and MEXT 9 an increase for I-131 was recorded and Cs-137 was no longer detectable.

No new data for the other sampling points have been reported at the date of 11 April 2011.

4. IAEA Activities

The team of three Agency experts in BWR technology have concluded their mission with meetings with NISA, Ministry of Foreign Affaires (MOFA), MEXT, Atomic Energy Commission (AEC) and Nuclear Safety Commission (NSC).

IAEA Update: New Earthquake in Japan (11 April 2011, 11:30 UTC)


The IAEA confirms that an earthquake occurred in Japan on 11 April at 08:16 UTC. The IAEA International Seismic Safety Centre has rated it as a 6.6 magnitude, revised from an initial 7.1 magnitude. The epicenter of the earthquake is 68 kilometres from the Fukushima Daiichi nuclear power plant, 60 kilometres from the Fukushima Daini nuclear power plant, 61 kilometres from Tokai Daini nuclear power plant, 173 kilometres from Kashiwazaki-Kariwa nuclear power plant, and 179 kilometres from Onagawa nuclear power plant. The epicenter was in land (37.01 N/ 140.48 E) at a depth of 13.1 km.

The IAEA has been in contact with Japan's Nuclear and Industrial Safety Agency (NISA) and can confirm the status of the following nuclear facilities:

Fukushima Daiichi Nuclear Power Plant

Based on a report by the Tokyo Electric Power Company (TEPCO), NISA confirms that no changes have been observed on the readings at the on-site radiation monitoring posts. Workers have been evacuated to the seismic evacuation shelter. Off-site power was lost and water injection pumps for Units 1, 2 and 3 stopped.

NISA confirms later that off-site power was restored and water injection resumed 50 minutes after the earthquake.

Fukushima Daini Nuclear Power Plant

NISA confirms that no changes have been observed on the readings at the on-site radiation monitoring posts and that off-site power remained available.

Onagawa Nuclear Power Plant

The five off-site power lines remain available. No changes have been observed on the readings at the on-site radiation monitoring posts.

Tokai Daini Nuclear Power Plant

The Tokai Daini nuclear power plant remains in cold shutdown since the 11 March earthquake. No abnormality has been observed.

IAEA Briefing on Fukushima Nuclear Accident (10 April 2011, 15:00 UTC)


Presentation
Summary of Reactor Status

On Sunday, 10 April 2011, the IAEA provided the following information on the current status of nuclear safety in Japan:

1. Current Situation

Earthquake of 7 April

External power has been restored at all sites affected by the 7 April earthquake. The 3 litres of water that were spilled at Onagawa nuclear power plant have been cleaned up.

Changes to Fukushima Daiichi Plant Status

Overall, the situation at the Fukushima Daiichi plant remains very serious but there are early signs of recovery in some functions such as electrical power and instrumentation.

In Units 1, 2 and 3, 60 000 tons of contaminated water need to be removed from the turbine buildings and trenches. This water will be transferred to the condensers of each unit and the Radioactive Waste Treatment facility. In addition, temporary storage tanks have been ordered to provide additional capacity for the water and will be located adjacent to the Radioactive Waste Treatment facility. In Unit 2 water transfer from the condenser to the condensate storage tank was completed on 9 April.

Nitrogen gas is being injected into the Unit 1 containment vessel to reduce the possibility of hydrogen combustion within the containment vessel. The pressure in this containment vessel is increasing due to the addition of nitrogen.

In Unit 1 fresh water is being continuously injected into the reactor pressure vessel through feed-water line at an indicated flow rate of 6 m3/h using a temporary electric pump with off-site power. In Units 2 and 3 fresh water is being continuously injected through the fire extinguisher lines at indicated rates of 7 m3/h and 7 m3/h respectively using temporary electric pumps with off-site power.

In Unit 1 the pressure in the RPV is increasing as indicated on both channels of instrumentation. NISA has indicated that some instruments in the reactor vessel may not be working properly. In Units 2 and 3 Reactor Pressure Vessel and Drywell pressures remain at atmospheric pressure.

RPV temperatures remain above cold shutdown conditions, typically less than 95 °C. In Unit 1 temperature at the feed water nozzle of the RPV is 235 °C and at the bottom of the RPV is 120 °C. In Unit 2 the temperature at the feed water nozzle of the RPV is 145 °C. The temperature at the bottom of the RPV was not reported. In Unit 3 the temperature at the feed water nozzle of the RPV is 97 °C and at the bottom of the RPV is 109 °C.

The concrete pump vehicle sprayed fresh water (90 T) to the spent fuel pool in Unit 4 on 9 April.

There has been no change in status in Units 4, 5 and 6 and the Common Spent Fuel Storage Facility.

2. Radiation Monitoring

On 9 April, deposition of both iodine-131 and cesium-137 was detected in 5 and 6 prefectures respectively. The values reported for iodine-131 ranged from 7.8 to 650 becquerel per square metre and for cesium-137 from 3.3 to 370 becquerel per square metre. The highest deposition was reported for both, iodine-131 and cesium-137, in the prefecture of Ibaraki.

Gamma dose rates are measured daily in all 47 prefectures, the values tend to decrease. Dose rates are also reported daily for the Eastern part of the Fukushima prefecture, these values are decreasing as well. As of 9 April, the gamma dose rates, reported for distances of more than 30 km to Fukushima-Daiichi, ranged from 0.2 to 26 μSv/h.

In an additional monitoring programme, set up by MEXT in cooperation with local universities, measurements are made in 27 cities in 14 prefectures. As of 9 April, in 19 cities, the gamma dose rates were below 0.1 μSv/h. In 7 cities, gamma dose rates range from 0.13 to 0.21 μSv/h. In Fukushima City, a value of 0.46 μSv/h was observed. Typical normal background levels are in the range of 0.05 to 0.10 μSv/hr.

As of 7 April, iodine-131 and cesium-137 was detectable in drinking water in a few prefectures at levels far below those that would trigger recommendations for restrictions of drinking water. As of 7 April, one restriction for infants related to I-131 (100 Bq/l) is in place as a precautionary measure in only one village of the Fukushima prefecture.

On 9 April, the IAEA Team made measurements at 8 different locations in the Fukushima area at distances of 32 to 62 km, North and North West from the Fukushima nuclear power plant. At these locations, the dose rates ranged from 0.4 to 3.7 microsievert per hour. At the same locations, results of beta-gamma contamination measurements ranged from 0.03 to 0.19 Megabecquerel per square metre.

3. Marine Monitoring

As reported in the brief of 8th April TEPCO is conducting a programme for seawater (surface sampling) at a number of near-shore and off-shore monitoring locations as illustrated in Map 1.

Map 1: TEPCO Seawater Sampling Locations:

TEPCO Seawater Sampling Locations



Until 3 April a general decreasing trend was observed at the sampling points TEPCO 1 to TEPCO 4. After the discharge of contaminated water on 4 April, a temporary increase has been reported. On 10 April new data (7 April sampling day) for all TEPCO sampling points have been reported. At the near-shore sampling points TEPCO 1, TEPCO 3 and TEPCO 4 a further decrease with respect to the results for the sampling day 5 April, in the concentration of I-131 and Cs-137 have been reported. At the sampling point TEPCO 2 a further increase in the concentration of I-131 (from about 40 kBq/l on 6 April to about 150 kBq/l) and Cs-137 (from about 25 kBq/l on 6 April to about 65 kBq/l) was observed.

For the six sampling points TEPCO 5 to TEPCO 10 on April 7 the following has been reported: as TEPCO 5, TEPCO 6 and TEPCO 10 a further decrease of the levels of I-131 below 0.2 kBq/l and of Cs-137 below 0.1 kBq/l were measured.

At TEPCO 7 an increase of the level of I-131 has been recorded. At TEPCO 8 and TEPCO 9 an increase in the levels of both I-131 and Cs-137 has been measured. The reading at TEPCO 9 is from about 0.07 kBq/l (6 April) to about 0.37 kBq/l for I-131 and from about 0.05 kBq/l to about 0.21 kBq/l for Cs-137.

MEXT Off-shore Monitoring Programme

As reported in the brief of 8 April MEXT initiated the off-shore monitoring program on 23 March and subsequently points 9 and 10 added to the off-shore sampling scheme. On 4 April, MEXT added two sampling points to the north and west of sampling point 1. These are referred to as points A and B on the map below.

Map 2: MEXT Seawater Sampling Locations:

TEPCO Seawater Sampling Locations



On 10 April new data have been reported (7 April sampling day) for the sampling points MEXT 6 and MEXT 10. At MEXT 6 sampling point an increase in I-131 (from about 18 Bq/l on 3 April to about 57Bq/l) and Cs-137 (from about 10Bq/l on 3 April to about 20 Bq/l) has been measured. At MEXT 10 the level of I-131 remains about 35 Bq/l as on 3 April; Cs-137 is no longer detectable.

No new data for the other sampling points have been reported at the date of 10 April.

4. IAEA Activities

The team of three Agency experts in BWR technology will conclude their mission on Monday with meetings with NISA, Ministry of Foreign Affairs (MOFA), MEXT, Atomic Energy Commission (AEC) and Nuclear Safety Commission (NSC).

In addition to those reported in previous briefs the following countries have submitted monitoring data and/or links to national websites where data is available: USA, Czech Republic and Latvia.

IAEA Briefing on Fukushima Nuclear Accident (9 April 2011, 15:00 UTC)


Presentation:
Summary of Reactor Status

On Saturday, 9 April 2011, the IAEA provided the following information on the current status of nuclear safety in Japan:

1. Current Situation

Earthquake of 7 April

The IAEA confirms that an earthquake occurred in Japan at 14:32 UTC, 7 April. The IAEA International Seismic Safety Centre has rated it as a 7.1 magnitude, revised from an initial 7.4 magnitude. The epicenter of the earthquake was 20 km from the Onagawa nuclear power plant and approximately 120 km from the Fukushima Daiichi and Daini nuclear power plants. With the recovery of external power at the Rokkasho Reprocessing Plant, all sites reported on yesterday have external power.

Changes to Fukushima Daiichi Plant Status

In Units 1, 2 and 3, 60 000 tons of contaminated water need to be removed from the turbine buildings and trenches. This water will be transferred to the condensers of each Unit and the Radioactive Waste Treatment facility. In addition, temporary storage tanks have been ordered to provide additional capacity for the water and will be located adjacent to the Radioactive Waste Treatment facility.

Nitrogen gas is continuing to be injected into the Unit 1 containment vessel to reduce the possibility of hydrogen combustion within the containment vessel. The pressure in this containment vessel is increasing due to the addition of nitrogen.

In Unit 1 fresh water is being continuously injected into the reactor pressure vessel through feed-water line at an indicated flow rate of 6 m3/h using a temporary electric pump with off-site power. In Units 2 and 3 fresh water is being continuously injected through the fire extinguisher lines at indicated rates of 8 m3/h and 7 m3/h respectively using temporary electric pumps with off-site power.

In Unit 1 the pressure in the RPV is increasing as indicated on both channels of instrumentation. NISA has indicated that some instruments in the reactor vessel may not be working properly. In Units 2 and 3 Reactor Pressure Vessel and Drywell pressures remain at atmospheric pressure.

RPV temperatures remain above cold shutdown conditions, typically less than 95 °C. In Unit 1 temperature at the feed water nozzle of the RPV is 246 °C and at the bottom of the RPV is 119 °C. In Unit 2 the temperature at the feed water nozzle of the RPV is 141 °C. The temperature at the bottom of the RPV was not reported. In Unit 3 the temperature at the feed water nozzle of the RPV is 89 °C and at the bottom of the RPV is 110 °C.

The concrete pump vehicle continued to spray fresh water to the spent fuel pool in Unit 3 on 8 April.

There has been no change in status in Units 4, 5 and 6 and the Common Spent Fuel Storage Facility.

2. Radiation Monitoring

On 8 April, low levels of deposition of both iodine-131 and cesium-137 were detected in 10 and 7 prefectures respectively. The values reported for iodine-131 ranged from 1 to 46 becquerel per square metre, for cesium-137 from 5 to 42 becquerel per square metre.

Gamma dose rates are measured daily in all 47 prefectures and the values continue to decrease. For Fukushima, on 8 April a dose rate of 2.3 µSv/h, for the Ibaraki prefecture a gamma dose rate of 0.15 µSv/h were reported. The gamma dose rates reported for the other 45 prefectures were below 0.1µSv/h.

Since the end of March, MEXT has set up an additional monitoring programme in cooperation with local universities. Measurements are made in 26 cities in 13 prefectures. As of 8 April, in 17 cities, the gamma dose rates were below 0.1 µSv/h. In 8 other cities, gamma dose rates ranged from 0.13 to 0.17 µSv/h, In Fukushima City, a value of 0.42 µSv/h was observed. Typical normal background levels are in the range 0.05 to 0.1 µSv/hr.

The IAEA Team in Fukushima made measurements on the 8 April at 8 different locations at distances of 24 to 42 km, in Northwesterly directions from the Fukushima nuclear power plant. At these locations, the dose rates ranged from 1.6 to 56 microsievert per hour. At the same locations, results of beta-gamma contamination measurements ranged from 0.2 to 5.0 Megabecquerel per square metre. The highest beta-gamma contaminations have been determined at distances of less than 30 km.

Since our written brief of yesterday, data related to food contamination has not been reported. However, on 8 April the Ministry of Health, Labour and Welfare reported that the Emergency Response headquarters had approved the lifting of restrictions on the distribution of unprocessed raw milk in certain locations in Fukushima prefecture (city of Kitakata and the towns of Aizumisato, Bandai, Inawashiro, Michima, Minamiaizu and Simogo) and on the distribution of spinach and kakina in Gunma prefecture.

As reported in the brief of 8 April TEPCO is conducting a programme for seawater (surface sampling) at a number of near-shore and off-shore monitoring locations as illustrated in the Map 1.

Map 1: TEPCO Seawater Sampling Locations

Until 3 April a general decreasing trend was observed at the sampling points TEPCO 1 to TEPCO 4. After the discharge of contaminated water on 4 April, a temporary increase has been reported.

On 6 April at the near-shore sampling points TEPCO 1, TEPCO 3 and TEPCO 4 a decrease in the concentration of I-131 and Cs-137 have been reported. However, at the sampling point TEPCO 2 an increase in the concentration of I-131 (from about 20 kBq/l on 5 April to about 40 kBq/l) and Cs-137 (from about 15 kBq/l on 5 April to about 25 kBq/l) was observed.

For the six sampling points TEPCO 5 to TEPCO 10 on 6 April levels of I-131 below 0.4 kBq/l and Cs-137 below 0.2 kBq/l were measured.

MEXT Off-shore Monitoring Programme

As reported in the brief of 8 April, MEXT initiated the off-shore monitoring program on 23 March and subsequently points 9 and 10 were added to the off-shore sampling scheme. On 4 April, MEXT added two further sampling points to the north and west of sampling point 1. These are referred to as points A and B on the map below.

Map 2: MEXT Seawater Sampling Locations

0n 9 April new data have been reported for samples taken on 5 April. These data were for the sampling points MEXT3 and MEXT5. At MEXT3 there was an increase from about 3 Bq/l on 1 April to about 10 Bq/l on 5 April for I-131. At MEXT5 there was an increase from about 12 Bq/l on 1 April to about 65 Bq/l for I-131and from about 15 Bq/l to about 40 Bq/l for Cs-137 on 5 April.

No new data for the other sampling points have been reported.

3. IAEA Activities

A team of three Agency experts in BWR technology continue to meet with TEPCO and NISA officials in Tokyo.

IAEA Briefing on Fukushima Nuclear Accident (8 April 2011, 15:00 UTC)


Presentation:
Summary of Reactor Status

On Friday, 8 April 2011, the IAEA provided the following information on the current status of nuclear safety in Japan:

1. Earthquake of 7 April

The IAEA confirms that an earthquake occurred in Japan at 14:32 UTC, 7 April. The IAEA International Seismic Safety Centre has rated it as a 7.1 magnitude, revised from an initial 7.4 magnitude. The epicenter of the earthquake was 20 km from the Onagawa nuclear power plant and approximately 120 km from the Fukushima Daiichi and Daini nuclear power plants.

The IAEA has been in contact with NISA and can confirm the status of the following nuclear facilities:

Fukushima Daiichi Nuclear Power Plant

No changes have been observed at the on-site radiation monitoring posts. The injection of water into the reactor pressure vessels of Units 1, 2 and 3 was not interrupted.

Fukushima Daini Nuclear Power Plant

No changes have been observed of the readings at the on-site radiation monitoring posts.

Onagawa Nuclear Power Plant

All reactors have been in cold shutdown since 11 March earthquake.

Two out of the three lines supplying off-site power to the site were lost following the 7 April earthquake. Off-site power continues to be supplied through the third line.

Cooling of the spent fuel pool was temporarily lost, but has subsequently been restored.

No change has been observed in the readings from the on-site radiation monitoring post. The status of the plant is currently being checked.

Tokai Daini Nuclear Power Plant

Tokai Daini nuclear power plant remains in cold shutdown since the 11 March earthquake. No abnormality has been observed.

Higashidori Nuclear Power Plant

The Higashidori nuclear power plant was shut down and in a maintenance outage at the time of the 7 April earthquake. Off-site power was lost temporarily. Emergency power supply to the site operated as expected until off-site power was restored. All the fuel had been removed from the reactor core and stored in the spent fuel pool. Cooling of the spent fuel pool is operational.

Tomari Nuclear Power Plant (in Hokkaido)

At the time of the 7 April earthquake Tomari Unit 1 and Unit 2 were in operation. Following the 7 April earthquake, the Hokkaido Electric Power Company reduced the generating power to 90% of capacity.

Rokkasho Reprocessing Plant

The Rokkasho Reprocessing Plant and uranium enrichment facility lost off-site power. Emergency power supply to the site is operating.

2. Current Situation

Overall, the situation at the Fukushima Daiichi plant remains very serious although there are early signs of recovery in some functions such as electrical power and instrumentation.

As of 6 April, TEPCO started injecting nitrogen gas to Unit 1 containment vessel to reduce the possibility of hydrogen combustion within the containment vessel.

The leakage of highly contaminated water from the 20 cm crack in the cable storage pit of Unit 2 directly to the sea reported on 2 April was stopped by injection of coagulation agents (liquid glass) on 5 April. Additional activities to secure the leak were reported finished on 6 April.

To prevent discharge of contaminated water from the Fukushima Plant to the open sea, construction work was carried out at the breakwater in the southern part of the Plant on 5 April.

In Unit 1 fresh water has been continuously injected into the reactor pressure vessel through feed-water line at an indicated flow rate of 6 m3/h using a temporary electric pump with off-site power. In Units 2 and 3 fresh water is being injected into the reactor pressure vessels continuously through the fire extinguisher lines at indicated rates of 8 m3/h and 7 m3/h using temporary electric pumps with off-site power.

The reactor pressure vessels' temperatures remain above cold shutdown conditions (normally less than 95 °C). In Unit 1 indicated temperature at the feed water nozzle of the RPV is 224 °C and at the bottom of RPV is 117 °C. The pressure in the RPV is increasing as indicated on both channels of instrumentation. NISA has indicated that some instruments in the reactor vessel may not be working properly. Drywell pressure is increasing slightly due to the addition of nitrogen. In Unit 2 the indicated temperature at the feed water nozzle of the RPV is 144 °C. The temperature at the bottom of RPV was not reported. Indicated Drywell pressure remains at atmospheric pressure. In Unit 3 the indicated temperature at the feed water nozzle of the RPV is 88 °C and at the bottom of RPV is 112 °C. Fresh water was sprayed onto the spent fuel pool by concrete pump vehicle (50t/h) from 21:53 UTC, 6 April.

No change in status in Units 4, 5 and 6 and the Common Spent Fuel Storage Facility.

2. Radiation Monitoring

On 7 April, low levels of deposition of both iodine-131 and cesium-137 were detected in 5 and 4 prefectures respectively. The values reported for iodine-131 ranged from 3.8 to 20 becquerel per square metre, for cesium-137 from 9.7 to 25 becquerel per square metre.

Gamma dose rates continue to decrease. For Fukushima, on 7 April a dose rate of 2.3 µSv/h, for the Ibaraki prefecture a gamma dose rate of 0.16 µSv/h was reported. Dose rates reported for the Eastern part of the Fukushima prefecture, for distances of more than 30 km to Fukushima-Daiichi, range from 0.2 to 28 µSv/h.

As part of a new measurement program carried out by MEXT in cooperation with universities, gamma dose rates have also been measured in 26 cities in 13 prefectures for the period 5 to 7 April. In 19 cities, all measurements are below 0.1µSv/h. In a further five cities, some measurements are up to 0.21µSv/h. In the city of Tsukuba in the prefecture of Ibaraki, dose rates are in the range 0.17 to 0.2 0 µSv/h. In Fukushima City, the range is 0.42 to 0.5 µSv/h. typical normal background levels are in the range 0.05 to 0.1 µSv/h.

As of 6 April, iodine-131 and cesium-137 was detectable in drinking water in a few prefectures at levels far below those that would initiate recommendations for restrictions of drinking water. As of 7 April, one restriction for infants related to I-131 (100 Bq/l) remains in place as a precautionary measure in only one village of the Fukushima prefecture.

Since our written briefing of yesterday, data related to food contamination was reported on 7 April by the Japanese Ministry of Health, Labour and Welfare. These reported analytical results covered a total of 63 samples taken from 5 - 7 April. Analytical results for 62 of the 63 samples for various vegetables, spinach and other leafy vegetables, various meats, unprocessed raw milk and seafood in nine prefectures (Chiba, Fukushima, Gunma, Hyogo, Ibaraki, Kanagawa, Niigata, Tochigi and Yamagata) indicated that I-131, Cs-134 and/or Cs-137 were either not detected or were below the regulation values set by the Japanese authorities. One sample of spinach (grown outdoors) taken on 6 April in Ibaraki prefecture was above the regulation value set by the Japanese authorities for I-131.

TEPCO is conducting a programme for seawater (surface sampling) at a number of near-shore and off-shore monitoring locations. The near-shore sampling point for Daiichi Units 1 - 4 is located 330 m south of their common discharge point. The near-shore sampling point for Daiichi Units 5 and 6 is located 30 m north of their common discharge point.

Until 3 April a general decreasing trend was observed at these sampling points. After the discharge of contaminated water on 4 April, a temporary increase has been reported. On 5 April a decrease was again observed at these points.

At the Daini site, near-shore samples are being collected at two locations: directly north of the common discharge point of Daini, and close to Iwasawa Beach, which is south of Daini nuclear power plant. The latter monitoring point is 16 km south of Daiichi nuclear power plant on the northern boundary of TEPCO's Hirono thermal power plant. Starting from 2 April, TEPCO collected samples at three additional sampling points lying on a north-south transect that runs parallel to the coast but at a distance of 15 km from the shore. On 4 April, a further set of three sampling points, also at 15 km from the shore, was added. All six sampling locations lie along a north-south transect.

Since 5 April TEPCO is sampling daily at 6 points situated 15 km offshore along a north-south transect. Levels of radionuclides reported at these locations for 5 of April are in the range 57 - 200 Bq/l for I-131, 57 - 310 Bq/l for Cs-134 and 18 - 320 Bq/l for Cs-137. Values of Cs-134 and Cs-137 measured at the sampling points situated at the North and South ends of the transect are considerably lower than those measured at the stations directly offshore from the release points.

MEXT initiated the off-shore monitoring program on 23 March. Initially, the monitoring was carried out at 8 points lying on a north-south transect parallel to the coast and 30 km off-shore. Sampling points 1 to 8 are separated by about 10 km. On 28 March, points 9 and 10 were added to the off-shore sampling scheme. Points 8, 9 and 10 lie in one line perpendicular to the coast. Points 8 to 10 are also separated by 10 km. On 4 of April MEXT added two sampling points to the north-west of sampling point 1. These are referred as point A and B. Monitoring at off-shore points consist of:

  • Measurements of ambient dose rate in air;
  • Collection and analysis of surface sample of seawater; and
  • Collection and analysis of samples of sea water collected 10 metres above the sea water bottom.

On 8 April the only data reported concerned the 15 km offshore north-south transect.

4. IAEA Activities

A team of three Agency experts in BWR technology continue to meet with TEPCO and NISA officials in Tokyo and are expected to be back in Vienna on 13 April 2011.

In addition to those reported in previous briefs the following countries have submitted monitoring data and/or links to national websites where data is available: Denmark, Germany, Lithuania, Luxembourg, Mexico and Portugal.

IAEA Briefing on Fukushima Nuclear Accident (7 April 2011, 18:00 UTC)


Presentations:
Summary of Reactor Status
Status of Fukushima Units
Fukushima Radiological Monitoring and Consequences
Fukushima Marine Environment Monitoring
Watch Video

On Thursday, 7 April 2011, the IAEA provided the following information on the current status of nuclear safety in Japan:

1. Current Situation

Overall, the situation at the Fukushima Daiichi plant remains very serious although there are early signs of recovery in some functions such as electrical power and instrumentation.

On 6 April it was reported that the leakage of water from the sidewall of the pit closest to the sea has stopped after coagulation agents (liquid glass) were injected into the holes drilled around the pits. Work continues to prevent further releases to the sea.

According to the TEPCO Press Release of 4 April, approximately 10 000 T of water from the radioactive waste treatment plant and 1 500 T of subsurface waters stored in the sub drain pits of Unit 5 and 6 are being discharged to the sea to provide room to store water with higher levels of radioactivity in a safer manner. TEPCO has estimated that these discharges would increase the effective dose to a member of the public by 0.6 mSv, if he/she were to eat seaweed and seafood from 1 km from the discharge point every day for a year. It should be noted however that the movements of all ships, including fishing boats, are restricted within a 30km zone from the NPP.

In Unit 1 fresh water is being continuously injected into the reactor pressure vessel through the feed-water line at an indicated flow rate of 6 m3/h using a temporary electric pump with off-site power. Fresh water is being injected continuously into the RPVs through the fire extinguisher lines in Units 2 and 3 at indicated rates of 8 m3/h and 7 m3/h respectively using a temporary electric pump with off-site power.

As of 6 April, TEPCO started injecting nitrogen gas to Unit 1 containment vessel to provide an inerted atmosphere to reduce the possibility of hydrogen combustion within the containment vessel.

On Unit 1 the indicated temperature at the feed water nozzle of the RPV is 224 °C and at the bottom of RPV it is 117 °C. Instrumentation "B" for Reactor Pressure indicates that the pressure in the RPV is increasing and instrumentation "A" indicates that it has stabilized. NISA has indicated that some instruments in the reactor vessel may not be working properly. Drywell pressure has increased slightly due to the injection of nitrogen. In Unit 2 the indicated temperature at the feed water nozzle of the RPV is stable at 143 °C. The temperature at the bottom of the RPV was not reported. Indicated Drywell pressure remains at atmospheric pressure. The indicated temperature at the feed water nozzle of the RPV in Unit 3 is 88 °C and at the bottom of the RPV is about 115 °C.

Additional water was injected via the Spent Fuel Cooling System line to the spent fuel pool by a temporary pump on 4 April.

There has been no change in status on Units 4, 5, 6 and the Common Spent Fuel Storage Facility.

2. Radiation Monitoring

On 6 April, low levels of deposition of both I-131 and Cs-137 were detected in 4 and 6 prefectures respectively. The values reported for I-131 ranged from 3.4 to 10 becquerels per square metre, for Cs-137 from 4.9 to 19 becquerels per square metre. Gamma dose rates continue decreasing. There is no significant change in gamma dose rates reported for 6 April compared to yesterday.

As of 5 April, I-131 and Cs-134/137 was detectable in drinking water in a small number of prefectures. All values were well below levels that would initiate recommendations for restrictions of drinking water. As of 6 April, one restriction for infants related to I-131 (100 Bq/l) is in place as a precautionary measure in only one village of the Fukushima prefecture.

TEPCO is responsible for near-shore sampling, taking samples of surface seawater. Samples near discharge areas are collected daily. Until 3 April a general decreasing trend was observed. However, after the discharge of contaminated water at 4 April, an increase from about 11 kBq/l as measured at 09:00 UTC to 41 kBq/l at 14:00 UTC for I-131; from 5.1 kBq/l at 09:00 UTC to 19 kBq/l for both, Cs-134 and Cs-137 at 14:00 UTC was recorded. On 5 April a decrease was observed as compared to the previous day, with seawater concentration of 5 kBq/l for Cs-137 and 11 kBq/l for I-131.

Since 4 April TEPCO added 3 new sampling points 15 km offshore, in addition to the already established 3 sampling points at the same distance, this resulting in a total of 6 sampling points situated along a north-south transect at a distance of 15 km from the coast.

Levels of radionuclides reported at these locations for 5 April are in the range 57 - 200 Bq/l for I-131, 18 - 310 Bq/l for Cs-134 and 18 - 320 Bq/l for Cs-137.

There were no new data for 30 km off-shore monitoring, carried out under the responsibility of MEXT, compared to yesterday's briefing.

On 6 April the marine expert from the IAEA Environment Laboratories Monaco completed his mission in Japan. From 2 to 4 April he embarked on the research vessel MIRAI to observe the sampling conducted 30 km offshore. He visited the JAEA laboratory in Tokai where the gamma spectrometric analyses are performed. He briefed representatives of the Japanese Government.

Since our written briefing of yesterday, data related to food contamination were reported on 6 April by the Japanese Ministry of Health, Labour and Welfare. These reported analytical results covered a total of 78 samples taken on 3 April (2 samples), 4 April (39 samples), 5 April (35 samples) and 6 April (2 samples). Analytical results for 52 of the 78 samples for various vegetables, spinach and other leafy vegetables, fruit (strawberries) and unprocessed raw milk in eight prefectures (Fukushima, Gunma, Hyogo, Ibaraki, Kanagawa, Niigata, Saitama and Yamagata) indicated that I-131, Cs-134 and/or Cs-137 were either not detected or were below the regulation values set by the Japanese authorities. However, it was reported that analytical results for 26 of the total 41 samples taken in Fukushima prefecture for various vegetables, spinach and other leafy vegetables indicated that I-131 and/or Cs-134/Cs-137 exceeded the regulation values set by the Japanese authorities.

On 5 April, the Japanese Ministry of Health, Labour and Welfare issued a press release indicating that a new provisional regulation value was set for I-131 at a limit of 2000 Bq/kg in fishery products.

As of 4 April, food restrictions (distribution and/or consumption) are in place in four prefectures (Fukushima, Ibaraki, Tochigi, and Gunma) and in certain locations in Chiba prefecture (Katori City, Tako Town and Asahi City).

In Fukushima, there are restrictions on the consumption of leafy vegetables, headed and non-headed leafy vegetables (e.g. spinach, komatsuna, cabbage), and flower-headed brassicas (broccoli, cauliflower). There are also restrictions on the distribution of headed and non-headed leafy vegetables, flower-headed brassicas (including turnips), spinach, kakina and unprocessed raw milk produced in the prefecture.

In Ibaraki, there are restrictions on the distribution of unprocessed raw milk, parsley, spinach and kakina produced in the prefecture.

In Chiba, there are restrictions on the distribution of spinach produced in Katori City and Tako Town. There are also restrictions on the distribution of spinach, chingensai, shungiku, sanchu, celery and parsley produced in Asahi City.

In Gunma and Tochigi, there are restrictions on the distribution of spinach and kakina produced in these prefectures.

3. IAEA Activities

The two agency experts in BWR technology are in Japan to have a direct exchange of views with the Japanese counterparts. They met with officials of NISA, TEPCO, the Japanese Atomic Energy Commission and the Nuclear Safety Commission. They visited the off-site emergency response center and the Fukushima Daiichi site. A third agency expert will join the team in Tokyo to have follow-up meetings with TEPCO and NISA at the end of the week.

The following countries have submitted monitoring data and/or links to national websites where data is available: Austria, Belgium, Bulgaria, Canada, China, Finland, France, Greece, Iran, Ireland, Italy, Malaysia, Poland, Romania, Russian Federation, Singapore, Spain, Sweden, Switzerland and Ukraine.

IAEA Update: New Earthquake in Japan (7 April 2011, 17:30 UTC)


The IAEA confirms that an earthquake occurred in Japan at 14:32 UTC, 7 April. The IAEA International Seismic Safety Centre has rated it as a 7.1 magnitude, revised from an initial 7.4 magnitude. The epicenter of the earthquake was 20 km from the Onagawa nuclear power plant and approximately 120 km from the Fukushima Daiichi and Daini nuclear power plants.

The IAEA has been in contact with NISA and can confirm the status of the following nuclear facilities:

Fukushima Daiichi Nuclear Power Plant

NISA confirms that no changes have been observed at the on-site radiation monitoring posts. The injection of water into the reactor pressure vessels of Units 1, 2 and 3 was not interrupted.

Fukushima Daini Nuclear Power Plant

NISA confirms that no changes have been observed of the readings at the on-site radiation monitoring posts.

Onagawa Nuclear Power Plant

All reactors have been in cold shutdown since the 11 March earthquake.

NISA has confirmed that two out of the three lines supplying off-site power to the site were lost following the 7 April earthquake. Off-site power continues to be supplied through the third line.

Cooling of the spent fuel pool was temporarily lost, but has subsequently been restored.

No change has been observed in the readings from the on-site radiation monitoring post. The status of the plant is currently being checked.

Tokai Daini Nuclear Power Plant

The Tokai Daini nuclear power plant remains in cold shutdown since the 11 March earthquake. No abnormality has been observed.

Higashidori Nuclear Power Plant

NISA has confirmed that the Higashidori NPP was in shutdown and in a maintenance outage at the time of the 7 April earthquake. Off-site power has been lost. Emergency power supply to the site is operating. All the fuel had been removed from the reactor core and stored in the spent fuel pool. Cooling of the spent fuel pool is operational.

Tomari Nuclear Power Plant (in Hokkaido)

At the time of the 7 April earthquake Tomari Unit 1 and Unit 2 were in operation. Following the 7 April earthquake, the Hokkaido Electric Power Company reduced the generating power to 90% of capacity.

Rokkasho Reprocessing Plant

NISA confirms that the Rokkasho Reprocessing Plant and uranium enrichment facility lost off-site power. Emergency power supply to the site is operating.

The IAEA will issue further information as soon as it becomes available.

Fukushima Nuclear Accident Update (6 April 2011, 15:15 UTC)


Japanese authorities have informed the IAEA that TEPCO has been authorized to begin injection of nitrogen into the primary containment vessel (PCV) of Unit 1 at the Fukushima Daiichi nuclear power plant. Injection of nitrogen is intended to displace oxygen inside the containment vessel, thereby reducing a risk of explosion due to the combustible combination of hydrogen and oxygen.

IAEA Briefing on Fukushima Nuclear Accident (6 April 2011, 14:00 UTC)


Presentation:
Summary of Reactor Status

On Wednesday, 6 April 2011, the IAEA provided the following information on the current status of nuclear safety in Japan:

1. Current Situation

Overall, the situation at the Fukushima Daiichi plant remains very serious.

TEPCO has identified a possible leakage path from the Turbine building of Unit 2 to the sea via a series of trenches/tunnels used to provide power to the sea water intake pumps and supply of service water to the reactor and turbine buildings. On 4 April, a tracer was used in an attempt to determine where the water was coming from. The tracer was also injected into two new bore holes that had been drilled near the pit. On 5 April it was confirmed that the tracer was seen leaking from the crack into the sea. Coagulation agents (liquid glass) were injected into the holes drilled around the pits to block leakage of water. It was reported that the leakage has currently stopped at 20:38 UTC on 5 April. Work continues to prevent further releases to the sea.

According to the TEPCO Press Release of 4 April, approximately 10 000 T of water from the radioactive waste treatment plant and 1 500 T of subsurface waters stored in the sub drain pits of Unit 5 and 6 are being discharged to the sea to provide room to store water with higher levels of radioactivity in a safer manner. The discharges started at 10:00 UTC and 12:00 UTC respectively on 4 April. TEPCO has estimated that these discharges would increase the effective dose to a member of the public by 0.6 mSv, if he/she were to eat seaweed and seafood from the discharge area every day for a year. It should be noted however that the movements of all ships, including fishing boats, are restricted within a 30km zone from the NPP, based on the hazardous area set by the Maritime Safety Agency. Also, Fukushima prefecture reported that no fishing has started beyond a 30km zone from the NPP in this prefecture.

In Unit 1 fresh water is being continuously injected into the reactor pressure vessel through feed-water line at an indicated flow rate of 6 m3/h using a temporary electric pump with off-site power. Fresh water is being injected continuously into the RPVs through the fire extinguisher lines in Units 2 and 3 at indicated rates of 8 m3/h and 7 m3/h respectively using a temporary electric pump with off-site power.

In Unit 1 the indicated temperature at the feed water nozzle of the RPV decreased from 234 °C to 222 °C and at the bottom of RPV stable at 115 °C. Instrumentation "B" for Reactor Pressure indicates that the pressure in the RPV is increasing and instrumentation "A" indicates that it has stabilized. NISA has indicated that some instruments in the reactor vessel may not be working properly. Drywell pressure is stable. In Unit 2 the indicated temperature at the feed water nozzle of the RPV is stable at 141 °C. The temperature at the bottom of RPV was not reported. Indicated Drywell pressure remains at atmospheric pressure. The indicated temperature at the feed water nozzle of the RPV in Unit 3 is stable at 85 °C and at the bottom of the RPV is about 115 °C.

Additional water was injected via Spent Fuel Cooling System line to the spent fuel pool in Unit 2 by a temporary pump on 4 April.

Power is available to instrumentation in Unit 3.

There has been no change in status on Units 4, 5, 6 and the Common Spent Fuel Storage Facility.

2. Radiation Monitoring

On 5 April, low levels of deposition of both iodine-131 and cesium-137 were detected in 5 and 7 prefectures respectively. The values for iodine-131 ranged from 12 to 70, for cesium-137 from 3.6 to 41 becquerel per square metre.

Gamma dose rates reported for 6 April showed no significant changes compared to yesterday. Since 23 March, values have tended to decrease. Gamma dose rates were reported for 45 prefectures to be between 0.02 to 0.1 microsievert per hour. In one prefecture the gamma dose rate was 0.16 microsievert per hour. These values are within or slightly above the natural background of 0.1 microsievert per hour.

As of 4 April, iodine-131 and cesium-134/137 was detectable in drinking water in a few prefectures. All values were far below levels that would initiate recommendations for restrictions of drinking water. As of 6 April, one restriction for infants related to I-131 (100 Bq/l) remains in place as a precautionary measure in only one village of the Fukushima prefecture.

On 6 April the IAEA monitoring team made measurements at 7 locations at distances of 23 to 39 km South and Southwest of the Fukushima nuclear power plant. The dose rates ranged from 0.04 to 2.2 microsievert per hour. At the same locations, results of beta-gamma contamination measurements ranged from 0.03 to 0.36 megabecquerel per square metre.

Since our written briefing of yesterday, data related to food contamination was reported on 5 April by the Japanese Ministry of Health, Labour and Welfare. These reported analytical results covered a total of 41 samples taken on 24 March (1 sample), 30 March (1 sample), 1 April (1 sample), 2 April (9 samples) and 4 April (29 samples). Analytical results for 40 of the 41 samples for various vegetables, spinach and other leafy vegetables, fruit (strawberries), chicken, poultry eggs, unprocessed raw milk and seafood in eight prefectures (Chiba, Fukushima, Gunma, Ibaraki, Kanagawa, Niigata, Saitama and Tokyo) indicated that iodine-131, caesium-134 and/or caesium-137 were either not detected or were below the regulation values set by the Japanese authorities. One sample of seafood (sand lance) taken on 4 April (offshore) in Ibaraki prefecture was above the regulation value set by the Japanese authorities for caesium-134/caesium-137.

TEPCO is responsible for near-shore sampling, taking samples of surface seawater. The near shore sampling point for Daiichi Units 1 - 4 is located 330 m south of their common discharge point. The near-shore sampling point for Daiichi Units 5 and 6 is located 30 m north of their common discharge point.

Samples near discharge areas are collected daily. Until 3 April a general decreasing trend was observed. However, after the discharge of contaminated water at 4 April, an increase from about 11 kBq/l at 09:00 UTC to 41 kBq/l at 14:00 UTC for I-131, and from 5.1 kBq/l at 09:00 UTC to 19 kBq/l for both, Cs-134 and Cs-137 at 14:00 UTC was detected.

There were no new data for off shore monitoring compared to yesterday's briefing.

3. IAEA Activities

The two agency experts in BWR technology in Japan are continuing their mission and will be joined by a third agency expert to have additional meetings with TEPCO at the end of the week. The marine expert from the IAEA Environment Laboratories Monaco, who joined the sampling campaign on the research vessel MARAI, returns to Vienna today.

Fukushima Nuclear Accident Update (6 April 2011, 08:15 UTC)


Leakage of Highly Contaminated Water into Sea

According to Japanese authorities, the leak of highly contaminated water from the cable storage pit located next to the Unit 2 inlet point at Fukushima Daiichi nuclear power plant has stopped as of 20:38 UTC on 5 April.

Workers had employed measures to stop the flow of water directly to the sea since 2 April, when the leak was first observed.

On April 2, concrete was poured into the pit in an attempt to stop the water leakage to the ocean, but no significant decrease in leakage was observed.

From 4:47 UTC to 5:30 UTC on 3 April, the top of the trench was broken open and polymer was poured into the trench to stop the leakage of water, but this measure was not successful.

Approximately 13 kg of liquid tracer was injected into the pit at 22:08 UTC, 3 April. The tracer was also injected into two new bore holes that had been drilled near the pit.

At 4:15 UTC, 5 April it was confirmed that the tracer was seen leaking from the crack into the sea.

At 6:07 UTC, 5 April coagulation agents (liquid glass) were injected into the holes drilled around the pits. The leakage was reported to have ceased at 20:38 UTC on April 5. Work continues to prevent further releases to the sea.

The photographs below represent the status of leakage before and after:


2 April 2011:

2 April 2011

5 April 2011, 20:38 UTC:

5 April 2011

Fukushima Nuclear Accident Update (5 April 2011, 20:25 UTC)


Japan Begins Discharge of Low Level Radioactive Water

Japanese authorities have confirmed to the IAEA that they began to discharge 11 500 tonnes of low level radioactive water from the Fukushima Daiichi nuclear power plant into the sea on 4 April. The operation is being conducted to create storage capacity for highly radioactive water that has pooled in parts of the reactor facility, hindering efforts to restore electrical power from the grid to the facility.

Japanese officials have reported that they plan to release 10 000 tonnes of water from a waste treatment facility and 1 500 tonnes from drainage pits around reactor Units 5 and 6. The operation is expected to last no more than five days.

IAEA Briefing on Fukushima Nuclear Accident (5 April 2011, 14:00 UTC)


Presentation:
Summary of Reactor Status

On Tuesday, 5 April 2011, the IAEA provided the following information on the current status of nuclear safety in Japan:

1. Current Situation

Overall, the situation at the Fukushima Daiichi plant remains very serious.

On 3 April, transferring of water from the Unit 1 condenser to the condenser storage tank was started in preparation for transferring water in the basement of the Unit 1 turbine building to the condenser. On 2 April, transferring of water from the Unit 2 condenser to the condenser storage tank was started in preparation for transferring water in the basement of the Unit 1 turbine building to the condenser.

TEPCO has identified a possible leakage path from the Turbine building of Unit 2 to the sea via a series of trenches/tunnels used to provide power to the sea water intake pumps and supply of service water to the reactor and turbine buildings. On 4 April, a tracer was used in an attempt to determine where the water was coming from. So far, the tracer has not been observed in the water leaking into the sea.

In Unit 1 fresh water has been continuously injected into the reactor pressure vessel through feed-water line at an indicated flow rate of 6 m3/h using a temporary electric pump with off-site power. In Units 2 and 3 fresh water is being injected continuously into the RPVs through fire extinguisher line at indicated rates of 9 m3/h and 7 m3/h using a temporary electric pump with off-site power.

In Unit 1 the indicated temperature at the feed water nozzle of the RPV decreased from 243 °C to 234 °C and at the bottom of RPV stable at 115 °C. The RPV pressure indications are fluctuating and Drywell pressure is stable. The RPV pressure indications for the 2 channels are diverging. For Unit 2 the indicated temperature at the feed water nozzle of the RPV is stable at 142 °C. The temperature at the bottom of RPV was not reported. Indicated Drywell pressure remains at atmospheric pressure. In Unit 3 the indicated temperature at the feed water nozzle of the RPV is stable at 114 °C and at the bottom of RPV is about 85 °C. The validity of the RPV temperature measurement at the feed water nozzle is still under investigation.

In Unit 2 additional water was injected via the Spent Fuel Cooling System line to the spent fuel pool by a temporary pump on 4 April. In Unit 4, 180 T of fresh water was sprayed to the spent fuel pool by concrete pump on 3 April.

There has been no change of status on Units 5 - 6 and the Common Spent Fuel Storage Facility.

2. Radiation Monitoring

On 3 April, deposition of both iodine-131 and cesium-137 was detected in 7 prefectures. The values for iodine-131 ranged from 2.4 to 82, for cesium-137 from 5.2 to 57 becquerel per square metre. On 4 April, deposition of iodine-131 was detected in 7 prefectures ranging from 3.1 to 75 becquerel per square metre. Deposition of cesium-137 in 6 prefectures ranging from 7.4 to 46 becquerel per square metre. Reported gamma dose rates in the 46 prefectures showed no significant changes compared to yesterday.

As of 3 April, iodine-131 and cesium-134/137 was detectable in 8 and 5 prefectures respectively. All values were well below levels that would trigger recommendations for restrictions of drinking water. As of 3 April, restrictions for infants related to I-131 (100 Bq/l) are in place in only one village of the Fukushima prefecture. The restriction is still in place as a precautionary measure.

Currently, the IAEA monitoring team is working in the Fukushima region. On 5 April, measurements were made at 7 locations at distances of 16 to 41 km, South and South West to the Fukushima nuclear power plant. The dose rates ranged from 0.3 to 31 microsievert per hour. At the same locations, results of beta-gamma contamination measurements ranged from 0.01 to 3.2 megabecquerel per square metre. The highest dose rates and beta gamma contaminations were measured at the location closest to the Fukushima Nuclear Power Plant.

Since our written briefing of yesterday, data related to food contamination was reported on 4 April by the Japanese Ministry of Health, Labour and Welfare. These reported analytical results covered a total of 24 samples taken on 31 March (4 samples) and 1, 3 and 4 April (20 samples). Analytical results for all of the 24 samples for various vegetables, fruit (strawberries) and seafood in five prefectures (Gunma, Ibaraki, Niigata, Saitama and Tochigi) indicated that iodine-131, caesium-134 and/or caesium-137 were either not detected or were below the regulation values set by the Japanese authorities.

The IAEA/FAO Food Safety Assessment Team has completed its tasks and returned to Vienna. The team met with relevant local government officials and stakeholders in the agriculture sector in the four prefectures (Fukushima, Ibaraki, Tochigi and Gunma) most affected by the nuclear emergency in Fukushima. The team were appraised on the local situation and provided relevant technical information.

On 31 March, the team reported to the Japanese Cabinet Office, the Ministry of Foreign Affairs, the Ministry of Health, Labour and Welfare, and the Ministry of Agriculture, Forestry and Fisheries in Tokyo. The team returned from their mission on 1 April.

Seawater is collected daily close to the discharge areas of Units 1 - 4 and of Units 5 and 6 at the Dai-ichi NPP. The data show a decreasing trend from 1 to 3 April from about 66 kBq/l to 24 kBq/l for I-131 and 21 kBq/l to 10 kBq/l for both Cs-134 and Cs-137 at Units 1 - 4. The concentrations at Units 5 and 6 also showed a decreasing trend until 3 April. These values were measured before the discharge of low level contaminated water authorised by the Japanese Government on 4 April.

New data were provided for the off-shore survey on 8 sampling points about 30 km east of the NPPs. Concentrations are between 5 and 18 Bq/l for I-131 and between roughly 1 and 11 Bq/l for Cs-137. For the new coverage of the coastal transect in the south, about 35 km south of Fukushima Daiini, the highest concentrations were detected at the sampling point closest to the coast in the south with about 38 Bq/l for I-131 and 4.5 Bq/l for Cs-137. The concentrations at all sampling points have decreased over time.

3. IAEA Activities

The two Agency experts in BWR technology are in Japan. A third Agency expert will join them in Tokyo to have additional meetings with TEPCO at the end of the week.

IAEA Briefing on Fukushima Nuclear Accident (4 April 2011, 12:15 UTC)


Presentations:
Summary of Reactor Status
Fukushima Radiological Monitoring

On Monday, 4 April 2011, the IAEA provided the following information on the current status of nuclear safety in Japan:

1. Current Situation

Power supply to the temporary electric pumps for water supply to the Reactor Pressure Vessels (RPV) of Units 1, 2 and 3 was switched from the temporary mobile power supply to the off-site power supply on 3 April.

Lighting in a part of Units 1 - 4 Turbine Building was restored on 2 April.

On 2 April, transferring of water from the Unit 1 condenser storage tank to the surge tank of the suppression pool was completed in preparation for transferring water in the basement of the Unit 1 turbine building to the condenser. Also on 2 April, transferring of water from the Unit 2 condenser to the condenser storage tank was started in preparation for transferring water in the basement of the Unit 1 turbine building to the condenser.

A second US Navy barge arrived on 2 April carrying fresh water that is being transferred to the first barge which is pumping water to the "filtered water tank".

TEPCO has identified a possible leakage path from the Turbine Building of Unit 2 to the sea via a series of trenches/tunnels used to provide power to the sea water intake pumps and supply of service water to the reactor and turbine buildings. Initial attempts on 2 April to stop the leak, by pouring concrete into the pit, were not successful. On 3 April, the top of the trench was broken open and polymer was poured into the trench in an attempt to stop the leakage of water to the sea through the pit, but leakage has not stopped as of 00:00 UTC on 4 April.

NISA have advised the IAEA that TEPCO have been given permission by the Government of Japan to discharge 10 000 ton of low level contaminated water from their radioactive waste treatment facility to the sea. This is in order to have sufficient capacity to store highly contaminated water found in the basement of the Unit 2 Turbine Building.

In addition TEPCO will discharge 1 500 ton of low level contaminated water in the sub-drain pit for Units 5 and 6 to prevent the water in the pit from leaking into the reactor buildings and potentially damaging safety-related equipment.

TEPCO has estimated that the potential additional annual dose to a member of the public would be approximately 0.6 millisieverts (mSv), if they ate seaweed and seafood caught, from near the plant, every day for a year.

As of 07:00 UTC, 4 April the discharge had not yet commenced. The IAEA have asked NISA for additional information.

In Unit 1 fresh water has been continuously injected into the reactor pressure vessel through the feed-water line at an indicated flow rate of 6 m3/h using off-site power. In Unit 2 and 3 fresh water is being injected continuously into the reactor pressure vessels through the fire extinguisher line indicated rates of 8 m3/h and 7 m3/h respectively using off-site power.

In Unit 1 the indicated temperature at the feed water nozzle of the RPV decreased from 253 °C to 243 °C and at the bottom of RPV it was stable at 113 °C. The RPV pressure indications are fluctuating and Drywell pressure is slightly increasing. The reliability of RPV pressure indications is in question. In Unit 2 the indicated temperature at the feed water nozzle of the RPV has decreased from 153 °C to 140 °C. The temperature at the bottom of RPV was not reported. Indicated Drywell pressure remains at atmospheric pressure. In Unit 3 the indicated temperature at the feed water nozzle of the RPV is stable at 114 °C and at the bottom of RPV is about 90 °C. The validity of the RPV temperature measurement at the feed water nozzle is still under investigation.

70 T of water was injected via the Spent Fuel Cooling System line to the spent fuel pool in Unit 2 by a temporary pump on 1 April. There has been no change in status in Units 4, 5 and 6. The temperature in the Common Spent Fuel Storage Facility was 32 °C at 23:10 UTC on 2 April.

2. Radiation Monitoring

Gamma dose rates are monitored in all prefectures continuously. Since 23 March, reported gamma dose rates in the 45 prefectures have decreased.

On 4 April the IAEA monitoring team made measurements at 7 locations at distances of 30 to 41 km South and Southwest of the Fukushima nuclear power plant. The dose rates ranged from 0.7 to 12.5 microsievert per hour. At the same locations, results of beta-gamma contamination measurements ranged from 0.1 to 2.0 megabecquerel per square metre.

Since our written briefing of 1 April 2011, significant data related to food contamination was reported on 1 April (33 samples), 2 April (64 samples) and 3 April (37 samples) by the Japanese Ministry of Health, Labour and Welfare. These reported analytical results covered a total of 134 samples taken on 15 March (2 samples), 29 - 31 March (77 samples) and 1 - 2 April (55 samples). Analytical results for 133 of the 134 samples for various vegetables, spinach and other leafy vegetables, mushrooms, fruit (strawberries), various meats (beef and pork), seafood and unprocessed raw milk in twelve prefectures (Chiba, Fukushima, Gunma, Ibaraki, Kanagawa, Kyoto, Niigata, Saitama, Shizuoka, Tchigi, Tochigi and Tokyo), indicated that iodine-131, caesium-134 and/or caesium-137 were either not detected or were below the regulation values set by the Japanese authorities. One sample of shiitake mushrooms taken on 1 April in Fukushima prefecture was above the regulation values set by the Japanese authorities for both iodine-131 and caesium-134/caesium-137.

Seawater is monitored by TEPCO near the discharge points of Daiichi and Daiini plants. For Daiichi Units 1 - 4, seawater is monitored 330 m south of the common discharge point; for Daiichi Units 5 and 6 seawater is sampled 30 m south of the common discharge point. On 1 April an additional 3 points at 15 km from these sites were added following the discovery of highly contaminated water leaking into the sea from the pit near Unit 2.

3. IAEA Activities

The two Agency experts in BWR technology have arrived in Japan. The objective of this expert visit is to have a direct exchange of views with the Japanese counterparts. They met with officials of NISA, TEPCO, the Japanese Atomic Energy Commission and the Nuclear Safety Commission. They will also visit the off-site emergency response center and possibly visit the Fukushima Daiichi site.

The marine expert from the IAEA Environment Laboratories Monaco travelled to Japan to observe and provide advice on the collection and analysis of seawater samples. He was embarked to the Research Vessel MIRAI on 2 April and was on board until the morning of 4 April.

Fukushima Nuclear Accident Update (3 April 2011, 17:15 UTC)


Japanese authorities today informed the IAEA of the following developments at the Fukushima Daiichi nuclear power plant:

In Units 1, 2 and 3, external power supply is now being used to power the pumps that are injecting fresh water into the reactors, thus replacing temporary electrical pumps.

The switch to external power supply occurred on 3 April at:

03:02 UTC (12:02 Japan time) for Unit 1.
03:12 UTC (12:12 Japan time) for Unit 2.
03:18 UTC (12:18 Japan time) for Unit 3.

Some lighting has been reactivated in the turbine buildings of Units 1, 2, 3 and 4.

IAEA Briefing on Fukushima Nuclear Accident (3 April 2011, 12:00 UTC)


Presentation:
Summary of Reactor Status

On Sunday, 3 April 2011, the IAEA provided the following information on the current status of nuclear safety in Japan:

1. Current Situation

Overall at the Fukushima Daiichi plant, the situation remains very serious.

On 2 April, transferring of water from the Unit 1 condenser storage tank to the surge tank of the suppression pool was completed in preparation for transferring water in the basement of the Unit 1 turbine building to the condenser. Also, on 2 April transferring of water from the Unit 2 condenser storage tank to the surge tank of the suppression pool was started in preparation for transferring water in the basement of the Unit 1 turbine building to the condenser.

A second US Navy barge arrived on 2 April carrying fresh water to be transferred to the "filtered water tank".

TEPCO has identified a possible leakage path from the Turbine building of Unit 2 to the sea via a series of trenches/tunnels used to provide power to the sea water intake pumps and supply of service water to the reactor and turbine buildings. As of 2 April, 07:25 UTC, the pouring of concrete was started in an attempt to stop the water leakage. As of 2 April, 10:15 UTC, pouring of concrete had ceased and no significant decrease in the rate of leakage was observed. There is a plan to inject polymer to attempt to stop the leakage. TEPCO announced on 2 April that, following the detection of highly contaminated water leaking through a crack found in a pit near Unit 2, they had added 3 additional sampling points at 15 km from Fukushima Daiichi and Fukushima Daiini.

Fresh water has been continuously injected into the Reactor Pressure Vessel (RPV) of Unit 1 through the feed-water line at an indicated flow rate of 8 m3/h using a temporary electric pump with diesel backup. Fresh water is being injected continuously into the RPVs in Units 2 and 3 at indicated rates of 9 m3/h and 7 m3/h respectively through the fire extinguisher lines using temporary electric pumps with diesel backup.

In Unit 1 the indicated temperature at the feed water nozzle of the RPV is relatively stable at 259 °C and at the bottom of RPV at 117 °C. The RPV pressure indications are fluctuating and Drywell pressure is slightly decreasing. In Unit 2 the indicated temperature at the feed water nozzle of the RPV has decreased slightly from 161 °C to 153 °C. The temperature at the bottom of RPV was not reported. Indicated Drywell pressure remains at atmospheric pressure. The indicated temperature at the feed water nozzle of the RPV in Unit 3 is stable at 118 °C and at the bottom of the RPV is about 92 °C. The validity of the RPV temperature measurement at the feed water nozzle is still under investigation.

Injection of water into the spent fuel pool in Unit 2 using the temporary pump was restarted on 1 April.

Units 5 and 6

Both units remain in cold shutdown with plant systems operating on off-site AC power.

Common Spent Fuel Storage Facility

The Common Spent Fuel Pool temperature is stable. TEPCO tested an "anti-scattering" agent (2 000 l) on 500 m2 area around the Common Spent Fuel Storage facility on 1t April. The purpose of spraying is to prevent radioactive particles from being dispersed from the plant by winds and rain.

2. Radiation Monitoring

On 2 April, deposition of iodine-131 was detected in 7 prefectures ranging from 4 to 95 becquerel per square metre. Deposition of cesium-137 in 6 prefectures was reported on 2 April ranging from 15 to 47 becquerel per square metre. Reported gamma dose rates in the 45 prefectures showed no significant changes compared to yesterday.

Most of the previously imposed recommendations for restrictions on drinking water have been lifted. As of 2 April, one recommendation for the restriction based on iodine-131 concentration was in place in one village in the Fukushima prefecture, which applied for infants only. Meanwhile, also in this village, the iodine-131 level in drinking water has dropped below 100 becquerel per litre, which is the recommended restriction level for intake by infants. The restriction is still in place as a precautionary measure of the local authority.

Currently, one IAEA monitoring team is working in the Fukushima region. On 2 April, measurements were made at 7 locations at distances of 32 to 62 km, North and Northwest to the Fukushima nuclear power plant. The dose rates ranged from 0.6 to 4.5 microsievert per hour. At the same locations, results of beta-gamma contamination measurements ranged from 0.09 to 0.46 megabecquerel per square metre.

3. BWR Experts

The two agency experts in BWR technology have arrived in Japan. The objective of this expert visit is to have a direct exchange of views with the Japanese counterparts.

4. TEPCO Employees

TEPCO had been investigating two employees who had been missing since the earthquake of 11 March. On 2 April NISA reported that on the afternoon of 30 March the two employees were found dead in the -1 Level of the Turbine Building of Unit 4.

IAEA Briefing on Fukushima Nuclear Accident (2 April 2011, 12:00 UTC)


Presentations:
Summary of Reactor Status

On Saturday, 2 April 2011, the IAEA provided the following information on the current status of nuclear safety in Japan:

1. Current Situation

Overall at the Fukushima Daiichi plant, the situation remains very serious.

In preparation for transferring water in the basement of the Unit 1 turbine building to the condenser, water in the condenser storage tank is being transferred to surge tank of the suppression pool since 31 March, 03:00 UTC. Water in the trench was transferred to a water tank at the central environmental facility main building. The water level in the trench was reduced by 1 metre to 1.14 metre below the top of the trench on 31 March. On Unit 2 in order to prepare for removal of the water from turbine building basement, pumping of water from the condenser to suppression pool water surge was started 29 March, 07:45 UTC and was finished 1 April, 02:50 UTC. On Unit 3 in order to prepare for removal of the water from the turbine building basement, pumping of water from the condenser to suppression pool water surge was started 28 March, 08:40 UTC and completed 30 March, 23:37 UTC.

In a press release on 2 April, NISA reported the following: Water, with a dose rate of greater than 1 000 millisievert/hr, was confirmed by TEPCO at around 00:30 UTC on 2 April, in a pit, housing cables located next to the Unit 2 sea water inlet point. There exists a crack on the sidewall of the pit, about 20 cm in length, and water inside the pit is confirmed to be leaking directly to the sea. The isotopic analysis of water samples from inside the pit, the sea and near the seawater inlet bar screen filter is in process. Currently a plan to patch the pit with concrete is underway to stop the leakage. An investigation on the leakage path to this pit is on-going and measures to stop leakage to the sea will be implemented.

Transfer of fresh water from a US Navy barge to the "filtered water tank" started on 1 April, 06:58 UTC, and was suspended on 1 April, 07:25 UTC due to a connection failure. A second US Navy barge left Onahama port and planned to arrive 2 April, 00:30 UTC.

On Unit 1 fresh water has been continuously injected into the reactor pressure vessel through the feed-water line at an indicated flow rate of 8 m3/h using a temporary electric pump with diesel backup. The indicated temperature at the feed water nozzle of the RPV has decreased from 256 °C to 249 °C and at the bottom of RPV decreased from 128 °C to 119 °C. There was a corresponding decrease in RPV pressure and Drywell pressure.

Fresh water is injected continuously through fire extinguisher line on Unit 2 at an indicated rate of 9 m3/h using a temporary electric pump with diesel backup. The indicated temperature at the feed water nozzle of the RPV has decreased from 165 °C to 161 °C. The temperature at the bottom of the RPV was not reported. Indicated Drywell pressure remains at atmospheric pressure.

On Unit 3 fresh water is being injected continuously at an indicated rate of 7 m3/h into the reactor core through the fire extinguisher line using a temporary electric pump with diesel backup. The indicated temperature at the feed water nozzle of the RPV is about 119 °C and at the bottom of RPV is about 90 °C.

Fresh water (90 T) was pumped into the spent fuel pool in Unit 1 using a concrete pumping truck on 31 March. In Unit 2, injection of water into the spent fuel pond using the temporary pump was restarted on 1 April, 05:56 UTC. Fresh water (180 T) was pumped into the spent fuel pool on Unit 4 using a concrete pumping truck on 1 April.

Units 5 and 6 remain in cold shutdown with plant systems operating on off-site AC power.

2. Radiation Monitoring

On 1 April, deposition of iodine-131 was detected in 7 prefectures ranging from 7 to 74 becquerel per square metre. Deposition of cesium-137 in 9 prefectures was reported on April 1st ranging from 2.9 to 76 becquerel per square metre. Reported gamma dose rates in the 45 prefectures showed no significant changes compared to yesterday.

The Ministry of Agriculture, Forestry and Fisheries of Japan informed the IAEA that, because of winter conditions, most cattle, pigs and chickens are presently kept indoors. Animals are primarily fed on stored dried grass, silage and grain that has not been contaminated by the releases from the Fukushima Daiichi NPP.

On 31 March, NISA reported that among the workers at the Fukushima Daiichi plant, 21 workers have received doses exceeding 100 mSv. No worker has received a dose above 250 mSv, which is the dose limit for emergency workers.

On the 30 March, 180 000 Bq/l of I-131 and 15 000 Bq/l of Cs-137 were detected in the vicinity of the discharge water outlet of Unit 4.

The data reported for 27 - 30 March indicated that the levels at 30 m from the common discharge point of Units 5 and 6 were relatively constant at 45 000 - 55 000 Bq/l for I-131 and 10 000 - 15 000 Bq/l for Cs-137.

In addition to the 8 sampling points 30 km from the coast two additional monitoring stations were added in the South, 10km and 20 km from shore. The values reported for 28 and 30 March indicate a non-uniform distribution and trend.

IAEA Briefing on Fukushima Accident (1 April 2011, 14.30 UTC)


Presentations:
Summary of Reactor Status
Fukushima Radiological Monitoring and Consequences
Fukushima Marine Environment Monitoring
Watch Video

On Friday, 1 April 2011, the IAEA provided the following information on the current status of nuclear safety in Japan:

1. Current Situation

Overall at the Fukushima Daiichi plant, the situation remains very serious.

The Unit 1 condenser is full. In preparation for transferring water in the basement of the turbine building to the condenser, water in the condenser storage tank is being transferred to the suppression pool surge tank since 31 March, 03:00 UTC. Water in the trench was transferred to a water tank at the central environmental facility process main building. In order to prepare for removal of the water from the turbine building basement in Unit 2, pumping of water from the condenser to the suppression pool water surge tank started at 07:45 UTC, 29 March. For Unit 3 pumping of water from the condenser to suppression pool water surge tank was started at 08:40 UTC, March 28 and was completed at 23:37 UTC on 30 March.

For Unit 1 fresh water has been continuously injected into the Reactor Pressure Vessel (RPV) through the feed-water line at an indicated flow rate of 8 m3/h using a temporary electric pump with diesel backup. In Unit 2 fresh water is injected continuously through the fire extinguisher line at an indicated rate of 8 m3/h using a temporary electric pump with diesel backup. In Unit 3 fresh water is being injected continuously at about 7 m3/h into the reactor core through the fire extinguisher line using a temporary electric pump with diesel backup.

The indicated temperatures at the feed water nozzle of the RPV and bottom of RPV on Unit 1 are stable at 256 °C and 128 °C respectively. There is a slight decrease in RPV and Drywell pressures. The indicated temperature at the feed water nozzle of the RPV of Unit 2 is stable at 165 °C. The temperature at the bottom of the RPV was not reported. Indicated Drywell pressure remains at atmospheric pressure. The indicated temperature at the feed water nozzle of the RPV in Unit 3 is stable at 101 °C and at the bottom of RPV is also stable at 112 °C. Indicated Drywell pressure remains slightly above atmospheric pressure. The validity of the RPV temperature measurement at the feed water nozzle is still under investigation.

The pumping of water into the Unit 1 Spent Fuel Pool by concrete pumping truck was started at 04:03 UTC on 31 March. Fresh water was sprayed to the spent fuel pool at the Unit 3 by the concrete pump on 31 March and to the spent fuel pool on Unit 4 on 1 April.

Units 5 and 6 remain in cold shutdown.

2. Radiation Monitoring

On 31 March, deposition of iodine-131 was detected by the Japanese authorities in 8 prefectures, and deposition of cesium-137 in 10 prefectures. In these prefectures where deposition of iodine-131 was reported, on 31 March, the range was from 29 to 1 350 becquerel per square metre. For caesium-137, the range was from 3.6 to 505 becquerel per square metre. In the Shinjyuku district of Tokyo, the daily deposition for iodine-131 was 50 becquerel per square metre and for cesium-137 it was 68 becquerel per square metre. No significant changes were reported in the 45 prefectures in gamma dose rates compared to yesterday. As of 28 March, recommendations for restrictions on drinking water are in place at two locations in the Fukushima prefecture and restrictions continue to apply for infants only. The IAEA monitoring team made additional measurements at 9 locations West of Fukushima-Daiichi nuclear power plant. The measurement locations were at distances of 30 to 58 km from the Fukushima nuclear power plant. The dose rates ranged from 0.4 to 2.3 microsievert per hour. At the same locations, results of beta-gamma contamination measurements ranged from 0.01 to 0.49 megabecquerel per square metre. The other team who had made monitoring measurements in Tokyo during the last week, has finished its activities.

Since our written briefing of yesterday, significant data related to food contamination was reported on 31 March by the Japanese Ministry of Health, Labour and Welfare. Reported analytical results covered 2 samples taken on 15 March and 109 samples from 27 - 31 March. Analytical results for 98 of the 111 samples for various vegetables, spinach and other leafy vegetables, fruit (strawberries), seafood, various meats (beef, chicken and pork) and unprocessed raw milk in eight prefectures (Chiba, Fukushima, Gunma, Ibaraki, Kanagawa, Niigata, Tochigi and Tokyo), indicated that iodine-131, caesium-134 and caesium-137 were either not detected or were below the regulation values set by the Japanese authorities. However, it was reported that analytical results in Chiba, Fukushima, Ibaraki and Tochigi prefectures for the remaining 13 of the total 111 samples for spinach and other leafy vegetables, parsley and beef indicated that iodine-131 and/or caesium-134 and caesium-137 exceeded the regulation values set by the Japanese authorities.

The following restrictions are in place (Ministry of Health, Labour and Welfare Press Releases, 21 and 23 March 2011):

  • Fukushima: Distribution and consumption of leafy vegetables (including broccoli, cabbage, cauliflower, kakina, komatsuna and spinach), turnip and unprocessed raw milk.
  • Ibaraki: Distribution of spinach, kakina, parsley and unprocessed raw milk.
  • Gunma: Distribution of spinach and kakina.
  • Tochigi: Distribution of spinach and kakina.

The Joint FAO/IAEA Food Safety Assessment Team has completed its mission and presented its report to the Japanese Cabinet Office, Ministry of Foreign Affairs, Ministry of Health, Labour and Welfare and the Ministry of Agriculture, Fisheries and Forestry on 31 March. The IAEA members of the Team are returning to Vienna today.

The Agency, in agreement with the Japanese government, will dispatch two reactor experts to Japan. They will hold meetings with the Nuclear Safety Commission, NISA, TEPCO and other Japanese counterparts from Monday, 4 April onwards. The objective of this visit is to exchange views with Japanese technical experts and to get first-hand information about the current status of reactors at Fukushima Daiichi, measures being taken and future plans to mitigate the accident.

The following countries have provided the monitoring data to the IAEA's Incident and Emergency Centre (IEC): Belgium, Bulgaria, Canada, Finland, France, Greece, Ireland, Italy, Malaysia, Russian Federation, Spain, Switzerland and Singapore.

IAEA Briefing on Fukushima Nuclear Accident (31 March 2011, 14:00 UTC) - Corrected


Presentation:
Summary of Reactor Status

On Thursday, 31 March 2011, the IAEA provided the following information on the current status of nuclear safety in Japan:

1. Current Situation

Overall at the Fukushima Daiichi plant, the situation remains very serious.

The Unit 1 condenser is full. Pumping water from the Unit-1 turbine building basement to the Unit 1 condenser has been stopped as of 22:30 UTC on 28 March. For Units 2 and 3, in order to prepare for removal of the water from the turbine building basement, pumping of water from the condenser to the suppression pool water surge tank started at 07:45 UTC, 29 March and 08:40 UTC, March 28 respectively.

For Unit 1 fresh water has been continuously injected into the Reactor Pressure Vessel (RPV) through the feed-water line at an indicated flow rate of 8 m3/h using a temporary electric pump with diesel backup. In Unit 2 fresh water is injected continuously through the fire extinguisher line at an indicated rate of 8 m3/h using a temporary electric pump with diesel backup. In Unit 3 fresh water is being injected continuously at about 7 m3/h into the reactor core through the fire extinguisher line using a temporary electric pump with diesel backup.

The indicated temperature at the feed water nozzle of the RPV on Unit 1 has decreased from 281 °C to 251 °C and at the bottom of RPV decreased from 134 °C to 128 °C. There appears to be a corresponding decrease in RPV pressure with a slight decrease in Drywell pressure. The indicated temperature at the feed water nozzle of the RPV of Unit 2 has increased from 177 °C to 181 °C. The temperature at the bottom of RPV was not reported. Indicated Drywell pressure remains at atmospheric pressure. The indicated temperature at the feed water nozzle of the RPV in Unit 3 is about 89 °C and at the bottom of RPV is about 114 °C. The validity of the RPV temperature measurement at the feed water nozzle is still under investigation.

No further information is available regarding the plan to commence the pumping of water into the Unit 1 Spent Fuel Pool by concrete pumping truck from 29 March. On Unit 2 the temporary electric pump supplying water to the spent fuel pool experienced a malfunction. Spent fuel pool water supply was changed to a fire truck pump but a crack was discovered in a hose on 30 March 04:10 UTC. Pumping water to the spent fuel pool was therefore stopped. Pumping was subsequently restored and water was fed into spent fuel pool in Unit 2 from 10:05 UTC on March 30. Water injection into the spent fuel pool in Unit 4 by concrete pump was completed at 09:33 UTC on March 30.

Units 5 and 6 remain in cold shutdown

2. Radiation Monitoring

On 30 March, deposition of iodine-131 was detected in 8 prefectures, and deposition of cesium-137 in 12 prefectures. On 30 March in the prefectures where deposition of iodine-131 was reported, the range was from 2.5 to 240 becquerel per square metre. For caesium-137, the range was from 3 to 57 becquerel per square metre. In the Shinjyuku district of Tokyo, the daily deposition of both iodine-131 and cesium-137 on 30 March was below 30 becquerel per square metre. No significant changes were reported in the 45 prefectures in gamma dose rates compared to yesterday.

Most of the previously imposed recommendations for restrictions on drinking have been lifted. As of 28 March, recommendations for restrictions based on I-131 concentration remain in place in four villages of in the Fukushima prefecture, in three of these villages, restrictions continue to apply for infants only.

Two IAEA teams are currently monitoring radiation levels and radioactivity in the environment in Japan. On 30 March, one team made gamma dose-rate measurements in the Tokyo region at 7 locations. Gamma-dose rates measured ranged from 0.03 to 0.28 microsievert per hour, which is within or slightly above the background. The second team made additional measurements at 7 locations in the Hirono area, South of Fukushima-Daiichi NPP. The measurement locations were at distances of 23 to 39 km from the Fukushima nuclear power plant. The dose rates ranged from 0.5 to 4.9 microsievert per hour. At the same locations, results of beta-gamma contamination measurements ranged from 0.04 to 0.34 Megabecquerel per square metre.

Since our briefing of yesterday, significant data related to food contamination has been submitted by the Japanese Ministry of Health, Labour and Welfare. Seventy-six samples were taken from 28 - 30 March, and reported on 30 March. Analytical results for 51 of the 76 samples for various vegetables, fruit (strawberries), seafood (sardines) and unprocessed raw milk in eight prefectures (Chiba, Fukushima, Gunma, Ibaraki, Kanagawa, Niigata, Saitama and Yamagata), indicated that iodine-131, caesium-134 and caesium-137 were either not detected or were below the regulation values set by the Japanese authorities. However, it was reported that analytical results in Fukushima prefecture for the remaining 25 of the 76 samples for broccoli, cabbage, rapeseed, spinach and other leafy vegetables, indicated that iodine-131 and/or caesium-134 and caesium-137 exceeded the regulation values set by the Japanese authorities.

The Joint FAO/IAEA Food Safety Assessment Team met with local government officials in Gunma prefecture on Wednesday. Farmers and producers were also represented and the meeting attracted media coverage. The questions to the IAEA/FAO team mainly focused on technical issues of remediation strategies, including the implications of long term releases if the NPP is not stabilized, the disposal of contaminated produce, mechanisms of 131I and 137Cs contamination, other possible radionuclides that may be produced/should be monitored, contamination of fruit and mushrooms, occupational exposure risks in the handling animals and agricultural products, feeding strategies for animals in affected areas, monitoring of soil and fallout and remediation strategies and methodologies. There were also discussions with producers and farmer organizations over the development of strategies for the next cropping season.

Local government officials briefed the FAO/IAEA Team on current knowledge of the extent of contamination in Gunma prefecture, including the principal agricultural products affected and levels of contamination found.

The Joint FAO/IAEA Team presented their report and responded to inquires at a follow-up inter-ministerial meeting in Tokyo. The meeting was attended by representatives of the Japanese Cabinet Office, Ministry of Foreign Affairs, Ministry of Health, Labour and Welfare and the Ministry of Agriculture. Strong interest was expressed as to the remediation of the agricultural land, continued possible contamination of agricultural products, and the need to maintain communication with relevant ministries in the future.

New results from the marine monitoring stations 30 km off-shore were reported for 28 March. These results indicate a decrease for the northernmost sampling station for I-131 and a slight increase for Cs-137 as compared to values measured on 27 March. For sampling points situated towards the south of the transect an increase has been recorded, both for I-131 and for Cs-137 as compared to the previous day, with maximum concentrations in water below 30 Bq/l and 20 Bq/l respectively, still considerably lower than the maxima recorded on 23 March. This increase can be correlated with trends in concentrations measured close to the discharge points.

The latest analyses in seawater 330 m south of the discharge point of NPP Units 1 - 4, and 30 m north of the discharge point of Units 5 - 6 were made available for 29 March. In particular readings of 130 000 Bq/l of I-131, 32 000 Bq/l of Cs-137 and 31 000 Bq/l of Cs-134 were reported near Units 1 - 4.

The Russian Federation, Ireland and Switzerland reported the detection of very small amounts of iodine-131 and cesium-137 in air. Highest levels found are in the order of a few millibecquerel per cubic meter. The levels are not of any radiological concern.

Correction: A previous version of this update mistakenly reported that Singapore has reported to the IAEA that it had detected very small amounts of iodine-131 and cesium-137 in air. Singapore has not made such a report.

IAEA Briefing on Fukushima Nuclear Accident (30 March 2011, 16.30 UTC)


Presentations:
IAEA Briefing on Fukushima Nuclear Accident
Summary of Reactor Status
Fukushima Radiological Monitoring and Consequences - Update
Fukushima Contaminated Water Flow Illustration
Fukushima Impact on Marine Environment
Fukushima Nuclear Power Plant Photos, 29 March 2011
Watch Video

On Wednesday, 30 March 2011, the IAEA provided the following information on the current status of nuclear safety in Japan.

1. Current Situation

Overall at the Fukushima Daiichi plant, the situation remains very serious.

With respect to the water that is present in the turbine buildings. In Unit 1, water has continued to be pumped into the condenser with 3 pumps (6.5 ton/hour each) and the water level has reduced from 40cm to 20cm. In Unit 2 from 07.45 UTC, pumping of water from the Condensate Storage Tank into the Surge Tank was started so that the that condenser can be drained to the Condensate Storage Tank and contaminated water can be pumped out from the Turbine building into the condenser. The same process of pumping the water from the Condensed Water Storage Tank into the Surge Tank was started on Unit 3 at 08.40 UTC on 28 March.

Near the Unit 3 building, 3 workers spilled water over themselves when removing a flange from seawater pipes on the residual heat removal system (RHR). After showering, contamination was not detected.

Fresh water has been continuously injected into the Reactor Pressure Vessel (RPV) through feed-water line at an indicated flow rate of 8.0 m3/h at Unit 1. The pumping of freshwater into the RPV has been switched from fire trucks to temporary electrical pumps with diesel generator. At Units 2 and 3 fresh water is being injected continuously through the fire extinguisher line at an indicated rate of 7 m3/h using a temporary electric pump.

The indicated temperature at the feed water nozzle of the RPV of Unit 1 has decreased from 323 °C to 281 °C and at the bottom of RPV remained stable at 134 °C. There is a corresponding decrease in Drywell pressure. At Unit 2 the indicated temperature at the feed water nozzle of the RPV has increased from 154 °C to 177 °C and at the bottom of RPV has increased from 78 °C to 88 °C. Indicated Drywell pressure remains at atmospheric pressure. For Unit 3 the indicated temperature at the feed water nozzle of the RPV is about 75 °C and at the bottom of RPV is about 116 °C. The validity of the RPV temperature measurement at the feed water nozzle is still under investigation.

With respect to the Spent Fuel Pools, it was planned to commence the pumping of water into the Unit 1 Spent Fuel Pool by concrete pumping truck from 29 March. Also, on 29 March pumping of fresh water into the Unit 2 spent fuel pool commenced via a temporary electrical pump. The temperature of the spent fuel pool is 46 °C as of 19:00 UTC, 29 March. For Unit 4 it was planned to commence pumping freshwater into the spent fuel pool on March 29. The IAEA has not received information on implementation of spraying activities in units 1 and 4.

Units 5 and 6 remain in cold shutdown

2. Radiation Monitoring

The majority of the recently measured radioactivity levels in drinking water are being reported below the levels established by the Japanese authorities which are 100 Bq/L of I-131 for infants; 300 Bq/L for adults and 200 Bq/L of Cs-137 for infants and adults. Previously imposed recommendations for restrictions on drinking water are being lifted in most of the affected locations. As of 28 March, recommendations for restrictions based on I-131 concentration remain in place in one village in the Fukushima prefecture. In three other locations of the Fukushima prefectures, restrictions continue to apply for infants only.

Two IAEA teams are currently monitoring radiation levels and radioactivity in the environment in Japan. On 29 March, one team made gamma dose-rate measurements in the Tokyo region at 8 locations. Gamma-dose rates measured ranged from 0.02 to 0.19 microsievert per hour, which is within or slightly above the background.

The second team made additional measurements at distances of 32 to 62 km, at directions North to Northwest from the Fukushima nuclear power plant. At these locations, the dose rates ranged from 0.5 to 6.8 microsievert per hour. At the same locations, results of beta-gamma contamination measurements ranged from 0.05 to 0.45 Megabecquerel per square metre.

Based on measurements of I-131 and Cs-137 in soil, sampled from 18 to 26 March in 9 municipalities at distances of 25 to 58 km from the Fukushima Nuclear Power Plant, the total deposition of iodine-131 and cesium-137 has been calculated. The results indicate a pronounced spatial variability of the total deposition of iodine-131 and cesium-137. The average total deposition determined at these locations for iodine-131 range from 0.2 to 25 Megabecquerel per square metre and for cesium-137 from 0.02-3.7 Megabecquerel per square metre. The highest values were found in a relatively small area in the Northwest from the Fukushima Nuclear Power Plant. First assessment indicates that one of the IAEA operational criteria for evacuation is exceeded in Iitate village. We advised the counterpart to carefully assess the situation. They indicated that they are already assessing.

As far as food contamination is concerned, 35 samples taken from 25-29 March, and reported on 29 March, for various vegetables, fruit (strawberry), seafood, pork and unprocessed raw milk in nine prefectures (Chiba, Gunma, Ibaraki, Kanagawa, Nagano, Niigata, Saitama, Tochigi and Yamagata), stated that results for iodine-131, caesium-134 and caesium-137 were either not detected or were below the regulation values set by the Japanese authorities.

The Joint FAO/IAEA Food Safety Assessment Team met with local government officials in Tochigi prefecture on 29 March and provided advice related to contamination of food and the environment.

Local government officials briefed the FAO/IAEA Team on the extent of contamination in Tochigi, the principle agricultural products affected, the main production areas and production methods (greenhouses, open-air), levels of contamination found (principally in air, tap/ground water and vegetables) and imminent plans to monitor soil contamination. A field visit also took place to a spinach producer outside Utsunomiya City.

Based on these latest discussions with the Tochigi authorities, it is apparent that the focus of the Joint FAO/IAEA mission has changed to some extent from the mechanisms of contamination to remediation strategies and techniques related to plant and animal production, food traceability and water/soil characterization.

The FAO/IAEA team is also meeting with the local government officials in Gunma prefecture today.

No new results from the marine monitoring stations 30 km off-shore as well as from close to the discharge, were reported since 27 March.

One IAEA staff member of the Monaco marine laboratory will fly to Japan on 31 March in order to join the Japanese team assessing marine environment.

The IAEA continues activities under the Joint Radiation Emergency Management Plan of the International Organisations through regular video/teleconferences. As of 30 March the WHO liaison officer is working in the IEC.

In response to the request for data on measurement, the IEC has received information from Singapore. The Singapore Authorities have sent reports on measurements in food imported from Japan (cabbages). Some samples were over the Codex Alimentarius values recommended for international trade. In Singapore no increase in gamma dose rates have been observed and no fission products have been found in air samples.

IAEA Briefing on Fukushima Nuclear Accident (29 March 2011, 16:30 UTC)


Presentations:
IAEA Briefing on Fukushima Nuclear Accident
Summary of Reactor Status
Fukushima Nuclear Power Plant Photos

On Tuesday, 29 March 2011, the IAEA provided the following briefing on the current status of nuclear safety in Japan:

1. Current Situation

The situation at the Fukushima Daiichi plant remains very serious.

Accumulated contaminated water was found in trenches located close to the turbine buildings of Units 1 to 3. Dose rates at the surface of this water were 0.4 millisieverts/hour for Unit 1 and over 1 000 millisieverts/hour for Unit 2 as of 18:30 UTC on 26 March. The Nuclear Safety Commission of Japan suggests that higher activity in the water discovered in the Unit 2 turbine building is supposed to be caused by the water, which has been in contact with molten fuel rods for a time and directly released into the turbine building via some, as yet unidentified path. An investigation is underway as to how the water accumulated in the trenches. Measurements could not be carried out at Unit 3 because of the presence of debris.

Fresh water has been continuously injected into the Reactor Pressure Vessels (RPVs) of Units 1, 2 and 3. From today at Unit 1, the pumping of fresh water through the feed-water line will no longer be performed by fire trucks but by electrical pumps with a diesel generator. The switch to the use of such pumps has already been made in Units 2 and 3. At Unit 3, the fresh water is being injected through the fire extinguisher line.

At Unit 1, there has been an increase in temperature at the feed-water nozzle of the RPV from 273.8 °C to 299 °C. The temperature at the bottom of the RPV remained stable at 135 °C. Temperatures at Unit 2 appear relatively stable at the same measurement points. At Unit 3, the temperature at the feed-water nozzle of the RPV is about 61.5 °C and 120.9 °C at the bottom of the RPV. The validity of the RPV temperature measurement at the feed water nozzle is still under investigation.

With the increase in temperature at Unit 1, there has been a corresponding increase in Drywell pressure. In the Drywell of Unit 2, the indicated pressure dropped slightly and is just above atmospheric.

It is planned to begin pumping fresh water into the spent fuel pool of Unit 4 today, on 29 March.

Units 5 and 6 remain in cold shutdown.

2. Radiation Monitoring

On 28 March, deposition of iodine-131 was detected in 12 prefectures, and deposition of cesium-137 in 9 prefectures. The highest values were observed in the prefecture of Fukushima with 23 000 becquerel per square metre for iodine-131 and 790 becquerel per square metre for caesium-137. In the other prefectures where deposition of iodine-131 was reported, the range was from 1.8 to 280 becquerel per square metre. For caesium-137, the range was from 5.5 to 52 becquerel per square metre. In the Shinjyuku district of Tokyo, the daily deposition of both iodine-131 and cesium-137 was below 50 becquerel per square metre. No significant changes were reported in the 45 prefectures in gamma dose rates compared to yesterday.

As of 28 March information on radioactivity in drinking water collected mainly from the Japanese Ministry of Health, Labour and Welfare indicates that recommendations for restrictions based on I-131 concentration remain in place only in four locations in the prefecture of Fukushima. To date, no recommendations for restrictions have been made based on Cs-137. The Japanese limits for the ingestion of drinking water by infants is 100 becquerel per litre.

Five soil samples, collected at distances between 500 and 1 000 metres from the exhaust stack of Unit 1 and 2 of the Fukushima Nuclear Power Plant on 21 and 22 March, were analysed for plutonium-238 and for the sum of plutonium-239 and plutonium-240. (Due to analytical reasons, the isotopes plutonium-239 and plutonium-240 cannot be measured separately). Plutonium-238 was detected in 2 of the 5 samples, while plutonium-239/240 was detected in all samples as expected.

Concentrations reported for both, plutonium-238 and plutonium-239/240 are similar to those deposited in Japan as a result of the testing of nuclear weapons. The ratio of the concentrations of plutonium-238 and plutonium-239/240 in two of the samples indicate that very small amounts of plutonium might have been released during the Fukushima accident, but this requires to be further clarified.

As far as food contamination is concerned, 63 samples taken from 24 - 29 March, and reported on from 27 - 29 March, for various vegetables, fruit (strawberries), mushrooms, eggs, seafood and pasteurized milk in eight prefectures (Chiba, Fukushima, Gunma, Ibaraki, Miyagi, Niigata, Tochigi and Yamagata), stated that results for iodine-131, caesium-134 and caesium-137 were either not detected or were below the regulation values set by the Japanese authorities.

The Joint FAO/IAEA Food Safety Assessment Team met with local government authorities in Ibaraki prefecture on Monday and provided advice related to contamination of food and the environment, including the mechanisms and persistence of such contamination, examples of remediation strategies, international standards and sampling plan designs and radionuclide transfer from soil to plants, particularly as related to rice production in the area.

Local government authorities briefed the FAO/IAEA Team on the extent of contamination in Ibaraki, the principle agricultural products affected, the main production areas and production methods (greenhouse, open-air) and levels of contamination found.

The FAO/IAEA team is also meeting with the local authorities in Tochigi prefecture today, and will meet with local government officials in Gunma tomorrow.

Sea Water Samples

No new results from the marine monitoring stations 30 km off-shore were reported for 27 or 28 March. However, new analyses in seawater 330 m east to the discharges point of NPP Units 1 - 4 were made available for 27 March. These concentrations show a significant decrease from 74 000 Becquerel per litre of iodine-131, 12 000 Becquerel per litre of cesium-137, and 12 000 Becquerel per litre of cesium-134 on 26 March to 11 000 Becquerel per litre of iodine-131 and 1 900 Becquerel per litre of cesium-137 on 27 March.

Sea water samples were also collected daily at a location 30 m from the common discharge point for Units 5 - 6. These results also show an increase in the radionuclide concentrations on 26 March. The sea water samples collected on March 27 show as well a decrease of the radionuclide concentration.

Fig. 1 and 2

It can be expected that the data will be quite variable in the near future depending on the discharge levels. In general, dilutions by ocean currents and into deeper waters as well decay of short lived radionuclides e.g. I-131 or I-132 will soon lead to lower values.

Marine Organisms

First analyses were reported in fish carried out by the National Research Institute of Fishery Research. 5 samples of fish were collected from the port of Choshi (Chiba prefecture) and 4 of 5 samples showed Cs-137 concentrations below limit of detection. In one sample Cs-137 was found with 3 Bq/kg (fresh weight) and it was reported that it was slightly above the limit of detection. This concentration is far below any concern for fish consumption.

It is still too early to draw conclusions for expected concentrations on marine food, because the situation may change rapidly, however, it is expected that the detected initial concentrations of seawater will soon drop to lower values by dilution and the levels in marine food will most likely not reach levels above given limits for consumption, (presuming that discharges of contaminated seawater from the reactor will not continue). It is not expected that fish or other marine food will be collected in a close area to the NPP Fukushima at the present situation. Some marine algae are known to accumulate in particular I-131 and Tc-99m. However, these values will soon be of no concern due to the short half-lives of the radionuclides mentioned.

Modelling Marine Dispersion

The Group SIROCCO of the Observatoire Midi-Pyrenées of the University of Toulouse, CNRS, is continuing to carry out model calculations. The model is based on an ocean circulation and current weather conditions and they results showed an initial north-eastern transport of liquid releases from the damaged reactors and the contaminated water would reach the northern monitored stations between 1 and 2 weeks later.

A model with tracer release directly in the sea show an along shore propagation in the southern direction and a northeast propagation moving away from the coast.

Fig. 3 and 4

With tracer release from atmospheric deposition, the propagation stretch offshore entering the Kuro-Shivo current in few days.

The first results are shown in Fig. 3 and 4. The data are converted into Bq/L by assuming arbitrary discharge or aerial release activities, respectively. The results should just be taken as indication of the dilution capacity and transport route of sea water.

Fukushima Nuclear Accident Update (28 March 2011, 23:00 UTC)


Japan Confirms Plutonium in Soil Samples at Fukushima Daiichi

After taking soil samples at the Fukushima Daiichi nuclear power plant, Japanese authorities today confirmed finding traces of plutonium that most likely resulted from the nuclear accident there. The Nuclear and Industrial Safety Agency told the IAEA that the Tokyo Electric Power Company (TEPCO) had found concentrations of plutonium in two of five soil samples.

Traces of plutonium are not uncommon in soil because they were deposited worldwide during the atmospheric nuclear testing era. However, the isotopic composition of the plutonium found at Fukushima Daiichi suggests the material came from the reactor site, according to TEPCO officials. Still, the quantity of plutonium found does not exceed background levels tracked by Japan's Ministry of Education, Culture, Sports, Science and Technology over the past 30 years.

IAEA Director General's Briefing: Fukushima Nuclear Accident (28 March 2011, 14:30 UTC)


Watch Video

Ladies and Gentlemen,

I will make a few general introductory remarks before handing over to my colleagues for the Technical Briefing. The current situation can be summarised as follows:

  • The situation remains very serious.
  • Priority now is to overcome the crisis.
  • We are also planning ahead.
  • The IAEA is doing everything in its power to help Japan.

Let me elaborate a little.

The crisis at the Fukushima Daiichi plant has still not been overcome and it will take some time to stabilise the reactors.

For now, radioactivity in the environment, foodstuffs and water - including the sea - is a matter of concern in the vicinity of the Fukushima plant and beyond. Current levels indicate a need for further comprehensive monitoring.

On the positive side, electrical power has been restored at Units 1, 2 and 3 and fresh water is now available on the site.

Since I addressed the special Board meeting a week ago, we have put two radiation monitoring teams on the ground in Japan.

An FAO/IAEA Food Safety Assessment Team is also now on the spot, meeting officials in prefectures affected by contamination.

In a crisis of this nature, it is vital to provide, and share, speedy and accurate information.

From the beginning, we have been working closely with the Japanese government and with the safety agency NISA.

My visit to Tokyo, and the presence of IAEA staff on the ground, have improved both the flow of information and the level of mutual understanding of a variety of technical issues.

This has been an interactive process: as well as receiving information, we have been asking questions, providing advice and obtaining clarifications.

On Friday (25 March 2011), I took part in a video conference with UN Secretary-General Ban Ki-Moon and the heads of a number of major Agencies.

I explained that we have been working fully in accordance with the Joint Radiation Emergency Management Plan of the International Organizations. The Plan is co-sponsored by fifteen organisations and the IAEA is the focal coordinating body.

Our Incident and Emergency Centre has distributed information, channelled offers of cooperation, sent missions to Japan, and coordinated with partners including WHO, FAO, WMO, ICAO and CTBTO.

I will meet the UN Secretary General and the heads of agencies again later this week at the Chief Executives' Board meeting in Kenya to strengthen coordination.

Ladies and Gentlemen,

The crisis is not yet over, but we need to start thinking about the future.

Once the situation has been stabilised, the Agency would like to send an international expert mission to conduct an assessment of the accident. This should include an element of peer review.

The Fukushima crisis has confronted the Agency and the international community with a major challenge.

It is vitally important that we learn the right lessons from what happened on 11 March, and afterwards, in order to strengthen nuclear safety throughout the world.

Following my statement at the Board of Governors meeting last week (21 March 2011), many countries joined my call for robust follow-up action.

I would therefore like to propose that a high-level IAEA Conference on Nuclear Safety should take place here in Vienna before the summer.

The Conference should cover the following points:

  • An initial assessment of the Fukushima accident, its impact and consequences;
  • Considering the lessons that need to be learned;
  • Launching the process of strengthening nuclear safety; and
  • Strengthening the response to nuclear accidents and emergencies.

The work ahead will be substantial. I firmly believe that the IAEA is the best venue for follow-up on the Fukushima accident. We have the necessary expertise, extensive membership and can ensure transparency.

I will keep you informed and count on your full support and cooperation.

Thank you.

IAEA Briefing on Fukushima Nuclear Accident (28 March 2011, 14:30 UTC)


Presentations:
IAEA Briefing on Fukushima Nuclear Accident
Summary of Reactor Status
Deposition/Time Integrated Concentration Model
Fukushima Potential Impact on Marine Environment
Fukushima Radiological Consequences
Watch Video

On Monday, 28 March 2011, Graham Andrew, Special Adviser to the IAEA Director General on Scientific and Technical Affairs, provided the following briefing on the current status of nuclear safety in Japan:

1. Current Situation

An earthquake of magnitude 6.5 occurred at on 27 March, 22:23 UTC near the east coast of Honshu. NISA has confirmed that there have been no abnormal radiation readings at the Onagawa nuclear power plant, the closest to the epicentre, whose three units remain in cold shutdown since the earthquake of 11 March. As of 02:30 UTC today, there were no reports of any problems at nuclear plants in Japan related to the latest seismic event.

Overall at the Fukushima Daiichi plant, the situation is still very serious.

NISA informed the Incident and Emergency Centre (IEC) that a meeting is planned with TEPCO to determine the origin and path of water in the turbine buildings of Units 1 to 4. As seen with the contaminated workers, high dose rates in the turbine buildings and contaminated water in the basements can hamper recovery efforts.

The pumping of contaminated water from the basement floor of Unit 1's turbine building into its main condenser is in progress, whereas at Unit 2 that process has not begun because the steam condenser is full. At Unit 3, the pumping of contaminated water and in particular where it is going, are under consideration. The issue is also being examined for Unit 4.

Temperatures measured at the feed water nozzle and at the bottom of the Reactor Pressure Vessel (RPV) continue to decrease slightly at Units 1 and 2, except the temperature at the feed water nozzle of Unit 1's RPV, which has slightly increased to 274 °C.

A positive development is that the pumping of fresh water into the reactor pressure vessel of Unit 1 is to switch from the use of fire trucks to temporary electrical pumps running on offsite power on 29 March. At Unit 2, this switch was carried out on 27 March, with a diesel generator as backup in case offsite power is interrupted. Fresh water is also being injected continuously into the reactor pressure vessel of Unit 3, albeit currently pumped by fire trucks. The switch to temporary electrical pumps for this Unit is planned for today.

On 27 March at Unit 3, water was sprayed into the spent fuel pool using a concrete pump truck, and seawater was also pumped in through the spent fuel cooling system. It is planned to start pumping fresh water into the spent fuel pool tomorrow.

It is also planned to commence pumping freshwater into the spent fuel pool of Unit 4 from tomorrow.

Units 5 and 6 remain in cold shutdown.

At noon today in Japan, the three workers mentioned in previous briefings were released from the National Institute of Radiological Sciences where they had been kept under observation. The result of analyses performed indicates that the level of localised exposure received by two of them is between 2 000 and 3 000 millisievert (i.e. somewhat lower than the previous estimate of 2 000 to 6 000 millisievert).

2. Radiation Monitoring

On 27 March, deposition of iodine-131 was detected in 9 prefectures, and deposition of cesium-137 in 4 prefectures. The highest values were observed in the prefecture of Tochigi with 320 becquerel per square metre for iodine-131 and 73 becquerel per square metre for caesium-137. In the other prefectures where deposition of iodine-131 was reported, on 27 March, the range was from 6.4 to 110 becquerel per square metre. For caesium-137, the range was from 16 to 61 becquerel per square metre. In the Shinjyuku district of Tokyo, the daily deposition of iodine-131 on 27 March was 100 becquerel per square metre, while for caesium-137 it was 36 becquerel per square metre. No significant changes were reported in the 45 prefectures in gamma dose rates compared to yesterday.

Two IAEA teams are currently monitoring radiation levels and radioactivity in the environment in Japan. One team made gamma dose-rate measurements in the Tokyo and Chiba region at 3 locations. Gamma-dose rates measured ranged from 0.08 to 0.13 microsievert per hour, which is within or slightly above the background. The second team made additional measurements at distances of 30 to 46 km from the Fukushima nuclear power plant. At these locations, the dose rates ranged from 0.5 to 3 microsievert per hour. At the same locations, results of beta-gamma contamination measurements ranged from 0.02 to 0.3 Megabecquerel per square metre.

New results from the marine monitoring stations 30 km off-shore were received for seawater samples taken on 26 March. The levels decreased at most of the locations. For iodine-131 the concentration results for four monitoring stations are between 6 to 18 becquerel per litre, and for caesium-137 between "below limit of detection" and 16 becquerel per litre. The dose rates measured on the sea surface remain relatively low between 0.04 and 0.1 microsievert per hour.

Samples collected on 26 March 330 metres east of the discharge point showed increasing concentrations. There were found to be 74 000 becquerel per litre for iodine-131, 12 000 becquerel per litre for caesium-137, and 12,000 becquerel per litre for caesium-134.

It is still too early to draw conclusions for expected concentrations in marine food, because the situation can change rapidly. Modelling results show an initial north-eastern transport of liquid releases from the damaged reactors.

Monitoring of iodine-131 and cesium-137 in drinking water is on-going. Iodine-131 has been monitored by the Japanese authorities in 2 of 10 samples taken in the Fukushima prefecture with values of 60 and 90 becquerel per litre. In the Ibaraki prefectures, iodine-131 was detected in 2 of 9 samples, the values were 40 and 90 becquerel per litre. The Japanese limits for the ingestion of drinking water by infants is 100 becquerel per litre.

As far as food contamination is concerned, samples reported from 26 to 27 March in six prefectures (Fukushima, Gunma, Ibaraki, Niigata, Tochigi and Yamagata) reported iodine-131 in asparagus, cabbage, celery, chive, cucumber, eggplant, leek, mushrooms, parsley, tomato, spinach and other leafy vegetables, strawberries and watermelon. One sample of hana wasabi taken on 24 March in Fukushima prefecture was above the regulation values set by the Japanese authorities. Caesium-137 was also measured above the regulation value in the same sample of hana wasabi, but in the remaining five prefectures, caesium-137 was not detected or the results were below regulation values.

The Joint FAO/IAEA Food Safety Assessment Team met with local government authorities in Fukushima on Sunday and discussed issues related to food contamination, including standards and sampling plan designs for radionuclides in food and the environment, radionuclide transfer from soil to plants, and mitigation strategies. The FAO/IAEA team also met with the local authority in Ibaraki prefecture today. They will have meetings with local government officials in Tochigi and Gunma tomorrow.

IAEA Briefing on Fukushima Nuclear Accident (27 March 2011, 13:30 UTC)


Presentation:
IAEA Briefing on Fukushima Nuclear Accident

1. Current Situation

The situation at the Fukushima Daiichi plant remains very serious.

The restoration of off-site power continues and lighting is now available in the central control rooms of Units 1, 2 and 3. Also, fresh water is now being injected into the Reactor Pressure Vessels (RPVs) of all three Units.

Radiation measurements in the containment vessels and suppression chambers of Units 1, 2 and 3 continued to decrease. White "smoke" continued to be emitted from Units 1 to 4.

Pressure in the RPV showed a slight increase at Unit 1 and was stable at Units 2 and 3, possibly indicating that there has been no major breach in the pressure vessels.

At Unit 1, the temperature measured at the bottom of the RPV fell slightly to 142 °C. At Unit 2, the temperature at the bottom of the RPV fell to 97 °C from 100 °C reported in the Update provided yesterday. Pumping of water from the turbine hall basement to the condenser is in progress with a view to allowing power restoration activities to continue.

At Unit 3, plans are being made to pump water from the turbine building to the main condenser but the method has not yet been decided. This should reduce the radiation levels in the turbine building and reduce the risk of contamination of workers in the turbine building restoring equipment.

No notable change has been reported in the condition of Unit 4.

Water is still being added to the spent fuel pools of Units 1 to 4 and efforts continue to restore normal cooling functions.

Units 5 and 6 remain in cold shutdown.

We understand that three workers who suffered contamination are still under observation in hospital.

2. Radiation Monitoring

Dose rates at the Fukushima site continue to trend downwards.

In 28 of the 45 prefectures for which data are available, no deposition of radionuclides was detected in the period 18 to 25 March. In seven of the other 17 prefectures, the estimated daily deposition was less than 500 becquerel per square metre for iodine-131 and less that 100 becquerel per square metre for caesium-137.

On 26 March, the highest values were observed in the prefecture of Yamagata: 7 500 becquerel per square metre for iodine-131 and 1200 becquerel per square metre for caesium-137. In the other prefectures where deposition of iodine-131 was reported, the daily range was from 28 to 860 becquerel per square metre. For caesium-137, the range was from 2.5 to 86 becquerel per square metre.

In the Shinjyuku district of Tokyo, the daily deposition of iodine-131 on 27 March was 220 becquerel per square metre, while for caesium-137 it was 12 becquerel per square metre.

No significant changes were reported in the 45 prefectures in gamma dose rates compared to yesterday. In general, gamma dose-rates tend to decrease due to the decay of short-lived radionuclides such as iodine-131.

Two IAEA teams are currently monitoring in Japan. One team made gamma dose-rate measurements in the Tokyo region at 8 locations. Gamma dose-rates measured ranged from 0.08 to 0.15 microsievert per hour, which is within or slightly above the normal background. The second team made additional measurements at distances of 30 to 41 km from the Fukushima nuclear power plant. At these locations, the dose-rates ranged from 0.9 to 17 microsievert per hour. At the same locations, results of beta-gamma contamination measurements ranged from 0.03 to 3.1 Megabecquerel per square metre.

The first results of aerial surveys of gamma dose-rates by the Japanese authorities have been received by the Incident and Emergency Centre. These are being analysed and will be presented when more detailed data have been received.

New data from monitoring of the marine environment, carried out from 24 March, 22:55 UTC to 25 March, 03:32 UTC about 30 km offshore, show a decrease in both caesium-137 and iodine 131. The contamination at these locations is influenced by aerial deposition of fallout as well as by the migration of contaminated seawater from the discharge points at the reactor. The measured radiation doses rates above the sea remain consistently low (between 0.04 and 0.1 microsievert per hour). The first results of model predictions received from the SIROCCO Group at the University of Toulouse are being assessed.

Recommendations relating to the restriction of drinking water consumption, based on measured concentrations of iodine-131, remain in place in seven locations (in one location for both adults and infants, and in six locations for infants).

As far as food contamination is concerned, samples taken from 23 to 25 March in five prefectures showed iodine-131 in unprocessed raw milk, but the levels were far below the regulation values set by the Japanese authorities. Caesium-137 was also detected in samples of unprocessed raw milk taken on 23 March in Chiba prefecture, but at levels far below the Japanese regulation values. Caesium-137 was not detected in any of the samples taken from 24-25 March in the other four prefectures.

Based on samples taken on 22 and 24-25 March, three prefectures (Chiba, Ibaraki and Tochigi) reported iodine-131 in celery, parsley, spinach and other leafy vegetables above the regulation values set by the Japanese authorities. Caesium-137 was also detected above the regulation values in one sample of spinach taken on 24 March in Tochigi prefecture, but in the remaining two prefectures, the results were below regulation values.

The Joint FAO/IAEA Food Safety Assessment Team arrived in Tokyo on Saturday. It will meet regulatory officials in various prefectures where food contamination has been detected. The team left for Fukushima early today. The Mission will assist and provide advice on sampling protocols, analytical procedures, data collected to date and actions taken by the Japanese authorities for the control of contaminated foods.

Fukushima Nuclear Accident Update (27 March 2011, 09:00 UTC)


According to the Japanese Prime Minister's office, TEPCO has begun work to remove water that has accumulated in the turbine buildings at the Fukushima Daiichi nuclear power plant. Workers have started to remove water from the Unit 1 turbine building to its main condenser and are making preparations to do the same at Unit 2. (A main condenser's function in a nuclear power plant is to condense and recover steam that passes through the turbine.) Work to remove water from the turbine buildings in Units 3 and 4 is currently under consideration.

Removal of water from the turbine buildings is an important step to continue power restoration to the plant.

The IAEA is seeking further updates from Japanese authorities on the progress of this process and will update as information becomes available.

Fukushima Nuclear Accident Update (27 March 2011, 03:00 UTC)


As previously reported, three workers at the Fukushima Daiichi nuclear power plant were exposed on 24 March to elevated levels of radiation. The IAEA has received additional information on the incident from the Japanese authorities.

For two of the three workers, significant skin contamination over their legs was confirmed. The Japanese authorities have stated that during medical examinations carried out at the National Institute of Radiological Sciences in the Chiba Prefecture, the level of local exposure to the workers' legs was estimated to be between 2 and 6 sieverts.

While the patients did not require medical treatment, doctors decided to keep them in hospital and monitor their progress over coming days.

Fukushima Nuclear Accident Update (27 March 2011, 01:15 UTC)


Brief Update on State of Fukushima Daiichi Reactors

AC Power-Units 1 to 4

The restoration work of off-site (i.e. grid) power is still in progress. Off-site power is now connected to Units 1 to 4.

Power distribution panels in the Power Centres of Units 2 and 4 have been connected to the off-site electricity supply, but individual components are still being checked prior to being energised.

The lighting in Units 1, 2 and 3 control rooms has been restored. Some instrumentation was recovered for Units 1, 2 and 4. However, due to the extent of damage inflicted by the earthquake and tsunami, at present it is not possible to estimate when the equipment may be returned to service.

AC Power-Units 5 and 6

Off-site power has been restored.

Unit 1

Fresh water continues to be injected into the reactor pressure vessel.

As of 25 March, 23:00 UTC, white "smoke" was confirmed to be emanating continuously from the reactor building.

Water sample taken from the stagnant water on the basement floor of the turbine building shows the presence of iodine-131, cesium-137 and cesium-134 to a level comparable to that measured in the turbine building of Unit 3 where three workers were exposed to elevated levels of radiation on 24 March.

Unit 2

Fresh water continues to be injected into the reactor pressure vessel.

As of 25 March, 23:00 UTC, white "smoke" was confirmed to be emanating continuously from the reactor building.

The spent fuel pool temperature increased and then stabilized at 57 °C as of 26 March, 00:30 UTC.

Unit 3

Fresh water is being injected into the reactor pressure vessel.

The temperature at the bottom of reactor pressure vessel has decreased to 100.4 °C on 26 March, 13:00 UTC. Seawater injection to the spent fuel pool is on-going.

White "smoke" emanating from the reactor building was still being observed as of 25 March, 23:00 UTC.

The dose rate in the reactor containment vessel and suppression chamber continued to decrease to 36.1 sieverts per hour and 1.4 sieverts per hour, respectively, as of 26 March, 13:00 UTC .

Unit 4

From March 22 to March 25, 130 to 150 tonnes of seawater was poured into the spent fuel pool each day using a concrete pump. Sea water was also poured in through the spent fuel cooling system from 24 March, 21:05 UTC to 25 March, 01:20.

White "smoke" was still being observed coming from the reactor building as of 25 March, 23:00 UTC.

Unit 5

The reactor remains in cold shutdown. Off-site power has been restored. The reactor water temperature increased to 43.8 °C.

The temperature in the spent fuel pool increased to 42.8 °C as of 26 March, 02:00 UTC.

Unit 6

The reactor remains in cold shutdown. Off-site power has been restored. The reactor pressure vessel water temperature decreased to 21.3 °C.

The spent fuel pool water temperature has slightly increased to 30.0 °C.

Fukushima Nuclear Accident Update (26 March 2011, 15:15 UTC)


The IAEA has been informed by Japanese authorities that fresh water is now being used in place of sea water to cool the reactor pressure vessels at Units 1, 2 and 3 at the Fukushima nuclear power plant. The switch to fresh water is preferable as it leaves fewer deposits in components and is less corrosive than sea water.

IAEA Briefing on Fukushima Nuclear Accident (26 March 2011, 14:30 UTC)


Presentation:
Summary of Reactor Status

On Saturday, 26 March 2011, Graham Andrew, Special Adviser to the IAEA Director General on Scientific and Technical Affairs, provided the following briefing on the current status of nuclear safety in Japan:

1. Current Situation

The situation at the Fukushima Daiichi plant remains very serious.

The restoration of off-site power is still progressing and instrumentation is being tested in Units 1, 2 and 4.

At Unit 1, the main change is the injection of freshwater to the Reactor Pressure Vessel (RPV). The temperature measured at the bottom of the RPV is stable at 144 °C. Pressure in the RPV, containment vessel and suppression pool have come back down after having increased from 22 to 24 March.

At Unit 2, the injection of freshwater to the RPV commenced at 01:00 on 26 March. The RPV temperature is stable at 100 °C at the bottom of the RPV. The pressure measured in the RPV and in the containment pressure vessel is stable at circa one atmosphere. Freshwater is also being injected in the RPV of Unit 3. Temperature measurement at the feed-water nozzle of Unit 3's RPV is still judged to be unreliable, but at the bottom of the RPV it is stable at 102 °C. White "smoke" continues to be emitted as of 23:00 UTC on 25 March from Unit 3, as it does from Unit 4. Unit 3 shows a consistently low containment drywell pressure of circa 1 atmosphere.

There have been high radiation readings in Units 1 and 3, the likelihood of damage to the containment integrity of Unit 3 is a cause for concern.

We understand that a total of 17 TEPCO workers and contractors have received doses between 100 and 180 millisievert. TEPCO measured the dose rate of 400 millisievert per hour above the surface of the water in the Unit 3 turbine building where 2 workers had been contaminated.

Units 5 and 6 are still in cold shutdown, with slight variations in RPV water temperatures (down a few degrees at Unit 5, up a few at Unit 6).

2. Radiation Monitoring

Deposition of radioactivity is monitored daily by Japanese authorities in all 47 prefectures. From 24 to 25 March, the daily level of deposition decreased in all but one prefecture. The highest value was observed in the prefecture of Ibaraki, where on 25 March a deposition of 480 becquerel per square metre for iodine-131 was observed; the highest value for caesium 137 was measured in Yamagata at 150 becquerel per square metre. For the Shinjyuku district of Tokyo, the additional deposition of iodine-131 and caesium-137 on 25 March was below 200 becquerel per square metre.

Monitoring of the marine environment has continued. New data for 21 to 25 March on radionuclide concentrations were made available for the discharge area 330 metres south of the pipeline of Fukushima Daiichi. The levels are generally quite high and vary significantly with time. The highest levels were detected at 25 March with, for example, 50 000 becquerel per litre of iodine-131, 7,200 becquerel per litre of caesium-137, and 7 000 becquerel per litre of caesium-134. Other short lived radionuclides were also reported. No new data has been reported by Japan from the monitoring stations located about 30 km offshore.

Monitoring of drinking water is on-going: iodine-131 in drinking water was detected on 24 March in 12 prefectures, whereas caesium-137 was detected in 6 of the 47 prefectures. In Tochigi, a value of 110 becquerel per litre was observed, which is above the recommended value for drinking water to be consumed by infants (i.e. 100 becquerel per litre). All other measurements were far below 100 becquerel per litre. All caesium-137 concentrations measured were lower than 10 becquerel per litre, which is significantly below the limit set by Japan of 200 becquerel per litre.

Environmental monitoring of soil, surface water, vegetation and air continues to be carried out in the Fukushima prefecture. The monitoring results indicate high levels of contamination. The values reported are generally consistent with measurements of gamma dose rates and beta-gamma contamination carried out by an IAEA monitoring team.

Two IAEA teams are currently monitoring in Japan. One team made gamma-dose rate measurements in Tokyo and the south of Tokyo in the prefecture of Kanagawa. Gamma-dose rates ranged from 0.05 to 0.2 microsievert. Another monitoring team made additional measurements at distances of 23 to 97 km (in a southerly and south westerly direction) from the Fukushima nuclear power plant. At these locations, the dose rates ranged from 0.73 to 8.8 microsievert per hour. At the same locations, results of beta-gamma contamination measurements ranged from 0.02 to 0.4 Megabecquerel per square metre.

Two prefectures (Ibaraki, Tochigi) reported iodine-131 in unprocessed raw milk, but the measurement results were below the regulation values set by the Japanese authorities. In addition, iodine-131 was not detected in any of the samples taken from the remaining four prefectures (Chiba, Gunma, Kanagawa and Saitama) and Tokyo. Caesium-137 was not detected in any of the samples.

For two prefectures (Ibaraki, Tochigi) iodine-131 and cesium-137 were reported in spinach and other leafy vegetables above the regulation values set by the Japanese authorities. However, iodine-131 and caesium-137 were either not detected or were below the regulation values, in all of the samples taken from the remaining four prefectures (Chiba, Gunma, Kanagawa and Saitama) and Tokyo. In all six prefectures and Tokyo, no iodine-131 and caesium-137 were detected in leeks, or measurements were well below the regulation values set by the Japanese authorities.

Fukushima Nuclear Accident Update (26 March 2011, 10:30 UTC)


IAEA Sends Second and Third Teams to Japan to Aid Response to Nuclear Emergency

The IAEA has dispatched additional teams to Japan to assist in the response to the Fukushima Daiichi nuclear power plant emergency.

On 24 March, a team of IAEA specialists travelled to Japan, where they will continue efforts to supplement Japan's radiation monitoring efforts. Team members include worker radiation protection experts and safeguards department officials.

On 25 March, a joint IAEA/Food and Agriculture Organization team departed Vienna. The three-person team included the Head of the IAEA Food and Environmental Protection Laboratory, an IAEA soil scientist, and an FAO food safety specialist from FAO's headquarters in Rome.

This food safety assessment team will provide advice and assistance on sampling and analytical strategies and will help interpret Japanese monitoring data.

Fukushima Nuclear Accident Update (26 March 2011, 05:15 UTC)


Brief Update on State of Fukushima Daiichi Reactors

Japanese authorities today confirmed a number of developments at the nuclear reactors at Fukushima Daiichi.

Unit 1

Workers have restored lighting in the control room and have recovered some instrumentation. As of 25 March, fresh water is now being pumped into the reactor pressure vessel (RPV) instead of seawater.

Unit 2

Seawater injection into the reactor pressure vessel continues, and RPV pressures remain stable.

Unit 3

Workers are now pumping fresh water into the RPV, while seawater is pumped into the spent fuel pool. In addition, firefighters sprayed water into the reactor building yesterday from the outside.

Unit 4

With no fuel in the RPV, concerns remain focused on the condition of the spent fuel pool, and workers continued to use a concrete pump truck to pour water into the pool from above while pumping seawater into the pool through the fuel pool cooling line.

Units 5 and 6

Both reactors have achieved safe, cold shutdown, and their fuel pool temperatures have stabilised at acceptable levels.

Fukushima Nuclear Accident Update (26 March 2011, 01:30 UTC)


Radioactive Materials Found in Japanese Seawater Sampling - Updated

Japanese authorities today reported data on radiation samples collected 30 kilometres off shore of the Fukushima Daiichi nuclear power plant on 24 March, and the levels of iodine-131 and cesium-137 showed slight variations from data collected at the same locations on 23 March (See previous update).

A vessel from the Japan Agency for Marine-Earth Science and Technology (JAMSTEC) collected water samples at eight points 30 kilometres from the coastline and found measurable concentrations of iodine-131 and cesium-137. The iodine concentrations measured were about at Japanese regulatory limits, and the cesium levels were well below those limits.

The IAEA's Environment Laboratories Monaco has received the data and offered this preliminary analysis:

Dilution, both into deeper layers and by dispersion along the prevailing ocean currents will lead to a rapid decrease of the initial surface contamination.

For the short term, iodine-131 will be the relevant radionuclide as far as doses are concerned, but for the long term, cesium-137 will be the more important radionuclide in the marine environment. It will be possible to follow this nuclide over long distances for several years.

It can be expected that radionuclides will take months or years to reach other shores of the Pacific. The main transport of contamination takes place by atmospheric transport over long distances.

IAEA Briefing on Fukushima Nuclear Accident (25 March 2011, 15:30 UTC)


Presentations:
Summary of Reactor Status
Fukushima Impact on Marine Environment
Fukushima Radiological Implications on Human Health
Radiation Doses in Perspective
Watch Video

On Friday, 25 March 2011, Graham Andrew, Special Adviser to the IAEA Director General on Scientific and Technical Affairs, provided the following information on the current status of nuclear safety in Japan.

1. Current Situation

There has not been much change at the Fukushima Daiichi plant over the last 24 hours. Some positive trends are continuing, but there remain areas of uncertainty that are of serious concern.

Unit 1 is with offsite AC power to the lighting of its central control room and to some of its instrumentation. Unit 3 now also has lighting to its central control room, but not power to its instrumentation. It remains too early to evaluate how much instrumentation may effectively be recovered at Units 1, 2, 3 and 4.

Reactor pressure is decreasing at Unit 1 and so is seawater injection. On the other hand, pressure readings in the reactor pressure vessels remain unreliable in Unit 2 and have become unreliable in Unit 3.

The temperature at the feed-water nozzle of the reactor pressure vessel continues to decrease (to 205 °C) at Unit 1, and at Unit 3 (42.8 °C), and it remains stable at Unit 2 (105 °C).

The dose rates in the containment vessel and suppression chamber have continued to decrease at Unit 1, and remained stable at Unit 2.

At Unit 3, radiation exposure of three TEPCO subcontracting workers has been confirmed. They were working in the basement, with contaminated water on the floor. Two of them were transferred to hospital with contamination of their feet.

There are no significant developments to report at Unit 4, where water spraying continues.

Units 5 and 6 remain in comparatively good condition. Temperatures at both, which had risen when the cooling pumps were briefly shut down in order to switch to off-site power, temperatures have since been restored to lower levels, and both units are still in cold shutdown. For the same reasons, a brief rise in temperature also occurred at the Common Spent Fuel Pool on 24 March.

2. Radiation Monitoring

On-site radiation monitoring at the Daiichi NPP indicates that dose rates continue to decrease.

Deposition of radioactivity is monitored daily by Japanese authorities in all 47 prefectures. From 23 March to 24 March, additional deposition has been detected in 7 of the 47 prefectures. Considerable variations are observed, the deposition at this day ranged from 42 to 16 000 Becquerel per square metre for iodine-131; the highest value determined for caesium-137 was 210 Becquerel per square metre. For the Shinjuku district of Tokyo, the deposition of iodine-131 on this day increased by 13 000 Becquerel per square metre, and the caesium-137 deposition by 160 Becquerel per square metre.

As far as the marine environment is concerned, sampling of air and seawater continues to be carried out by the Japanese Ministry of Education, Culture, Sport, Science and Technology (MEXT). Results are sent to the IAEA Monaco laboratory for assessment.

Measurements in the marine environment have been carried out 30 km off-shore and 330 metres from the discharge points on 23 March and repeated the next day. The results made available up to 25 March indicate concentrations of iodine-31 (some 80 becquerel/litre) and caesium-137 (about 26 becquerel/litre). This contamination is most likely due to atmospheric fallout rather than just ocean currents. Dilution in the ocean is expected to decrease rapidly this initial surface contamination. Caesium-137 will be more important over the long term owing to its half-life (30 years) compared to that of iodine-131 (8 days). Modelling of the dispersion of these radionuclides has been started, and the first results are becoming available. Marine dispersion will of course be much slower than atmospheric transport.

Since yesterday, additional data has been made available by the Japanese authorities concerning radionuclide concentrations in milk, vegetables and drinking water.

Levels of iodine-131 exceeded levels recommended by the Japanese authorities in five raw milk samples taken in Fukushima Prefecture, and exceeded levels of iodine-131 and cesium-137 in one vegetable (mizuna) sampled in Ibaraki Prefecture.

Monitoring of drinking water is on-going, iodine-131 in drinking water was detected in 13 prefectures, caesium-137 was detected in 6 of the 47 prefectures. During the period of 19 to 23 March, all results remained below the limits set by the Japanese government. However, permissible levels of iodine-131 were exceeded in drinking water samples taken in the Fukushima and Ibaraki Prefectures and in Tokyo from 17 to 23 March. More positively, the iodine-131 levels in drinking water for Tokyo are now below limits for consumption for infants recommended by the Japanese authorities and restrictions have been lifted.

As a result of food monitoring where contamination exceeded the levels recommended by the Japanese authorities, current restrictions on the distribution of milk are in place in 2 prefectures (Fukushima, Ibaraki) and on the distribution of certain vegetables in 4 prefectures (Fukushima, Ibaraki, Tochigi, Gunma). This regulatory approach is to prevent food contaminated with radioactivity above these limits entering the market and thereby, ensure the safety of foods. On 23 March, the Japanese authorities requested sampling of agricultural products in 6 neighbouring prefectures (Miyagi, Yamagata, Saitama, Chiba, Niigata and Nagano). This request for further food monitoring covers the same types of foods currently under restriction.

The joint FAO/IAEA food safety mission is currently travelling to Japan.

On 25 March, the IAEA radiation monitoring team made additional measurements at distances from 34 to 62 km from the Fukushima nuclear power plant. At these locations, the dose rate ranged from 0.73 to 8.8 microsievert per hour. At the same locations, results of beta-gamma contamination measurements ranged from 0.07 to 0.96 Megabecquerel per square metre.

Director General Amano had a video conference today with the UN Secretary General and the Heads of a number of other UN system organizations concerning the accident. In addition, close coordination led by the IAEA through the Joint Radiation Emergency Management Plan of International Organizations (JPLAN) continues.

Fukushima Nuclear Accident Update (25 March 2011, 15:45 UTC)


Japanese authorities have informed the IAEA that on 24 March, examinations of the thyroid glands in 66 children (14 of which are infants) were conducted near the evacuation area around the Fukushima nuclear plant. The exams were conducted at the Kawamata Town Health Center (40-50 kilometres from Fukushima Daiichi NPP) and Kawamata Town Yamakiya Branch Office (30-40 kilometres from Fukushima Daiichi NPP).

According to a 25 March 2011 Nuclear and Industrial Safety Agency press release, the results of the examinations indicated that the dose rate "of all the 66 children including 14 infants from 1 to 6 years old had no big difference from the level of background and was at the level of no problem in light of the view of Nuclear Safety Commission."

Regarding developments at the Fukushima Daiichi nuclear power plant, "white smoke" was reported at Units 1, 2 and 4 from 21:20 UTC on 24 March. Sea water injection to Units 1, 2, 3 and 4 continues as of 23:00 UTC 24 March.

The IAEA is seeking further information on the latest status of all Units and spent nuclear fuel at Fukushima Daiichi NPP.

Fukushima Nuclear Accident Update (25 March 2011, 05.15 UTC)


Update on Conditions of Fukushima Daiichi Nuclear Power Plant

At Unit 1 workers have advanced the restoration of off-site electricity and lighting in the Unit's main control room was recovered as of 24 March, 11:30 UTC. They are now checking the availability of the cooling system.

While the pressure in the reactor vessel remains high, Japanese authorities are reporting that it has stabilized.

At Unit 2 engineers are working for the recovery of lighting in the main control room, and the instrumentation and cooling systems.

At Unit 3, around 120 tonnes of seawater was injected in the spent fuel pool via the cooling and purification line. The operation was carried out between 23 March, 20:35 UTC and 24 March, 07:05 UTC.

Work was under way for the recovery of the instruments and cooling systems. However, it had to be suspended because three workers were exposed to elevated levels of radiation on 24 March.

At Unit 4, the spent fuel pool was sprayed with around 150 tonnes of water using concrete pump truck. The operation was carried out between 24 March, 05:36 UTC and 06:30 UTC of the same day.

At Units 5 and 6, repair of the temporary pump for Residual Heat Removal (RHR) was completed as of 24 March, 07:14 UTC, and cooling started again 21 minutes later.

At the Common Spent Fuel, the power supply was restored as of 24 March, 06:37 UTC and cooling started again 28 minutes later. Work is now under way for the recovery of the lighting and instrumentation systems.

As of 24 March, 09:40 UTC, the water temperature of the pool was around 73 °C.

As of 24 March, 10:30 UTC workers continue to inject seawater into the reactor pressure vessels of Units 1, 2 and 3 and are preparing to inject pure water.

Fukushima Nuclear Accident Update (25 March 2011, 02.50 UTC)


As previously reported, three workers at the Fukushima Daiichi nuclear power plant were exposed on 24 March to elevated levels of radiation. The IAEA has received additional information on the incident from the Japanese authorities.

The three were contracted workers laying cables in the turbine building of the Unit 3 reactor. Two of them were found to have radioactivity on their feet and legs.

These were washed in the attempt to remove radioactivity, but since there was a possibility of Beta-ray burning of the skin, the two were taken to the Fukushima University Hospital for examination and then transferred to Japan's National Institute of Radiological Sciences for further examination. They are expected to be monitored for around four days.

It is thought that the workers ignored their dosimeters' alarm believing it to be to be false and continued working with their feet in contaminated water.

The Nuclear and Industrial Safety Agency (NISA) of Japan instructed TEPCO to review the radiation control system immediately in order to avoid similar incidents in the future.

As of 24 March, 19:30 Japan time, the number of workers at the Fukushima Daiichi nuclear power plant found to have received more than 100 millisieverts of radiation dose totalled 17 including the three contract workers. The remaining fourteen are TEPCO's employees.

IAEA Briefing on Fukushima Nuclear Accident (24 March 2011, 21.30 UTC)


Presentation:
Summary of Reactor Status

On Thursday, 24 March 2011, Graham Andrew, Special Adviser to the IAEA Director General on Scientific and Technical Affairs, provided the following information on the current status of nuclear safety in Japan.

1. Current Situation

As far as the reactors at the Fukushima Daiichi site are concerned, there is some good news to report from the last 24 hours, although the overall situation is still very serious.

With AC power connected, instrumentation continues to be recovered in Units 1, 2 and 4. Workers returned after being evacuated from Units 3 and 4 on March 23, following confirmation that black smoke emissions from Unit 3 had ceased.

Reactor pressure is increasing in Unit 1, pressure readings are unreliable in Unit 2, and stable in Unit 3 as water continues to be injected through their feed-water pipes. The temperature at the feed-water nozzle of the Reactor Pressure Vessel (RPV) is decreasing at Units 1 (243 °C) and 3 (about 185 °C), and stable at Unit 2 (about 102 °C).

Units 5 and 6 are still under cold shutdown, they are undergoing maintenance using off-site AC power and existing plant equipment.

Dose rates in the containment vessels and suppression chambers of Units 1 and 2 have decreased slightly.

2. Radiation Monitoring

The IAEA radiation monitoring team made additional measurements at distances from 21 to 73 km from the Fukushima nuclear power plant. At distances between 34 and 73 km, in a westerly direction from the site, the dose rate ranged from 0.6 to 6.9 microsievert per hour. At the same locations, results of beta-gamma contamination measurements ranged from 0.04 to 0.4 Megabecquerel per square metre.

At distances between 30 and 32 kilometers from the Fukushima Nuclear Power Plant, in a north westerly direction from the site, dose rates between 16 and 59 microsievert per hour were measured. At these locations, the results of beta-gamma contamination measurements ranged from 3.8 to 4.9 Megabecquerel per square metre. At a location of 21 km from the Fukushima site, where a dose rate of 115 microsieverts per hour was measured, the beta-gamma contamination level could not be determined.

The second IAEA monitoring team has started their work today in Fukushima and Tokyo. Measurements will be taken to determine more precisely the actual radionuclides that have been deposited.

On-site monitoring by the Japanese authorities at the Daiichi nuclear power plant produced new data on 23 March for radionuclide concentrations in the air from samples collected between 19 and 23 March. Of the six radionuclides monitored, only iodine-131 was found to be in excess of the limits set by Japan. Overall, the dose rates reported on the site have decreased from 1930 to 210 microsievert per hour between 21 to 23 March.

There continues to be considerable daily variation in the deposition of iodine-131 and caesium-137 reported in 10 Prefectures. Recent rainfall and the resulting wet deposition may help explain the increased deposition in Tokyo. As measured by the Japanese authorities for the Shinjuku district of Tokyo, iodine-131 deposition increased by 36 000 Becquerel per square metre from 22 to 23 March, and caesium-137 deposition by 340 Becquerel per square metre.

Monitoring of the marine environment by ships of the Japanese Ministry of Education, Culture, Sport, Science and Technology has now begun. Seawater and air samples were collected on 23 March in coastal waters, at distances of about 30 km off-shore. Dose rate measurements were also taken. Results from 24 March indicate surface seawater concentrations at eight locations ranging from 24.9 to 76.8 Becquerel per litre for iodine-131, and 11.2 to 24.1 Becquerel per litre for caesium-137. Radionuclide concentrations in dust in the air above the sea were also measured. The results are being assessed by experts from the IAEA's Environment Laboratories Monaco.

New data provided by the Japanese authorities has been made available concerning radionuclide concentrations in foodstuffs, milk and drinking water. Sampling has been most thorough and extensive in the Fukushima and Ibaraki Prefectures. Of the 11 varieties of vegetables sampled from 18 to 22 March iodine-131 and caesium-137 levels exceed limits set for food and drink ingestion. Permissible levels of iodine-131 and caesium-137 (one sample) were also exceeded in nearly all of the milk samples taken in Fukushima and Ibaraki Prefectures between 16 to 21 March. In addition, permissible levels of iodine-131 were exceeded in drinking water samples taken in the Fukushima and Ibaraki Prefectures and in Tokyo from 17 to 23 March. Further sampling and analysis will be carried out in the days ahead by the Japanese authorities. A joint FAO/IAEA mission to Japan will be undertaken to provide advice and assistance on sampling strategies, analysis and the interpretation of data collected by the Japanese authorities related to food contamination.

In summary, radioactivity in the environment, foodstuffs and water is moving more to the forefront, as some technical concerns related to the status of the reactors at the Fukushima Daiichi site appear to be slightly less acute in some respects. However, the overall situation on the Fukishima site remains very serious.

Fukushima Nuclear Accident Update (24 March 2011, 17:30 UTC)


Japanese Seawater Samples Show Signs of Radioactive Materials

Japanese authorities today provided the IAEA with data on seawater samples they collected on 22 and 23 March, after detecting iodine and cesium in the water near the Fukushima Daiichi nuclear power plant. (See earlier update.)

A vessel from the Japan Agency for Marine-Earth Science and Technology (JAMSTEC) collected water samples at several points 30 kilometres from the coastline and found measurable concentrations of iodine-131 and cesium-137. The iodine concentrations were at or above Japanese regulatory limits, and the cesium levels were well below those limits.

The IAEA's Marine Environmental Laboratory in Monaco has received the data for review.

Fukushima Nuclear Accident Update (24 March 2011, 17:25 UTC)


Japanese Workers Treated for Radiation Exposure

Japanese authorities today reported that three workers at the Fukushima Daiichi nuclear power plant were exposed to elevated levels of radiation. The three were working in the turbine building of reactor Unit 3 and have received a radiation dose in the range of 170-180 millisieverts.

Two of the workers have been hospitalized for treatment of severely contaminated feet, which may have suffered radiation burns. The workers had been working for about three hours in contact with contaminated water.

The IAEA is seeking additional information.

Fukushima Nuclear Accident Update (24 March 2011, 15:00 UTC)


Presentation:
Summary of Reactor Status

The IAEA today released updated summary slides on reactor conditions at Fukushima Daiichi nuclear power plant.

Fukushima Nuclear Accident Update (24 March 2011, 14:00 UTC)


Spent Fuel Pools at Fukushima Daiichi Nuclear Power Plant - Updated

Spent fuel removed from a nuclear reactor is highly radioactive and generates heat. This irradiated fuel needs to be stored for one to three years in pools that cool the fuel, shield the radioactivity, and keep the fuel in the proper position to avoid fission reactions. If the cooling is lost, the water can boil and fuel rods can be exposed to the air, possibly leading to severe damage and a large release of radioactive materials.

Nuclear power plants must replace fuel every one to two years, and the Fukushima Daiichi reactors typically remove about 25 percent of the reactor's fuel - to be replaced with fresh, or unirradiated, fuel - during each refuelling outage. The spent fuel, which is hottest immediately after it is removed from the reactor, is placed in the spent fuel pool until it is cool enough to be moved to longer-term storage.

The concern about the spent fuel pools at Fukushima Daiichi is that the capability to cool the pools has been compromised. See diagram below for location of the pool in each reactor building.

Number of Fuel Assemblies in Cooling Pools at Fukushima Daiichi
(Reported 17 March by Japan's Ministry of Economy, Trade and Industry)

Capacity Irradiated Fuel Assemblies Unirradiated Fuel Assemblies Most Recent Additions of Irradiated Fuel
Unit 1 900 292 100 March 2010
Unit 2 1240 587 28 September 2010
Unit 3 1220 514 52 June 2010
Unit 4 1590 1331 204 November 2010
Unit 5 1590 946 48 January 2011
Unit 6 1770 876 64 August 2010

Here is a summary of spent fuel conditions at Fukushima Daiichi nuclear power plant, based on documents and confirmed by Japanese officials (new information in bold):

Unit 1

Unit 1 experienced an explosion on 12 March that destroyed the outer shell of the building's upper floors. No precise information has been available on the status of the spent fuel pool.

Unit 2

Precise information on the status of the spent fuel pool was unavailable in the days following the earthquake, but Japan's Nuclear and Industrial Safety Agency began to release temperature data on 20 March:

20 March, 23:00 UTC: 49 °C
21 March, 05:25 UTC: 50 °C
21 March, 21:20 UTC: 51 °C
22 March, 02:20 UTC: 53 °C
22 March, 06:30 UTC: 50 °C
22 March, 19:20 UTC: 51 °C
23 March, 00:00 UTC: 51 °C
23 March, 06:00 UTC: 51 °C
23 March, 16:00 UTC: 52 °C
24 March, 00:00 UTC: 47 °C

Workers conducted an operation to spray 40 tonnes of seawater to the spent fuel pool on 20 March, and they added another 18 tonnes on 22 March.

Unit 3

Unit 3 experienced an explosion on 14 March that destroyed the outer shell of the building's upper floors. The blast may have damaged the primary containment vessel and the spent fuel pool. To address these concerns, authorities began spraying water into the building, first by helicopter on 17 March and then by fire trucks and other vehicles through 22 March. Starting 23 March, seawater was injected into the spent fuel using the cooling and purification line. By midday 24 March, 4-5 tonnes of seawater had been injected through this line.

Unit 4

This reactor was shut down 30 November 2010 for routine maintenance, and all the fuel assemblies were transferred from the reactor to the spent fuel pool, before the 11 March earthquake. The heat load in this pool is therefore larger than the others.

On 14 March, the building's upper floors were severely damaged, possibly causing a reduction of cooling capability in the spent fuel pool. Emergency workers began spraying water into the building on 20 March, and have continued daily since then. On 22 March, workers began using a concrete pump truck that can deliver water more effectively, placing 150 tonnes of water on 22 March and 130 tonnes on 23 March.

Units 5 and 6

Instrumentation at these reactors began to indicate rising temperatures at their spent fuel pools starting on 14 March. Three days later, Japanese technicians successfully started an emergency diesel generator at Unit 6, which they used to provide power to basic cooling and fresh-water replenishment systems. Workers created holes in the rooftops of both buildings to prevent any hydrogen accumulation, which is suspected of causing earlier explosions at Units 1 and 3.

A second diesel generator came online on 18 March, and the next day, the higher-capability Residual Heat Removal (RHR) system recovered full function. External power was restored to Units 5 and 6 on 22 March. Temperatures in the spent fuel pools of Units 5 and 6 have gradually returned to significantly lower temperatures, although the Unit 5 pool temperature increased somewhat on 23 March after pumps for the RHR system were stopped when the diesel generators were removed from service.

Common Use Spent Fuel Pool

In addition to pools in each of the plant's reactor buildings, there is another facility - the Common Use Spent Fuel Pool - where spent fuel is stored after cooling at least 18 months in the reactor buildings. This fuel is much cooler than the assemblies stored in the reactor buildings. Japanese authorities confirmed as of 18 March that fuel assemblies there were fully covered by water, and the temperature was 57 °C as of 20 March, 00:00 UTC. Workers sprayed water over the pool on 21 March for nearly five hours, and the temperature on 23 March was reported to be 57 °C.

Fukushima Nuclear Accident Update (23 March 2011, 20:00 UTC)


Brief Update on State of Fukushima Daiichi Reactors

Japanese authorities today announced a number of developments at Fukushima Daiichi nuclear power plant, where reactor cooling systems were disabled following the massive earthquake and tsunami on 11 March.

At Units 1, 2, 3 and 4, workers have advanced the restoration of off-site electricity, and the lights are working in Unit 3's main control room.

Black smoke was seen emerging from the Unit 3 reactor building, spurring the temporary evacuation of workers from Units 3 and 4. The emission of smoke has now decreased significantly.

Crews continued today to use a concrete pump truck to deliver high volumes of water into the Unit 4 spent fuel pool, where there are concerns of inadequate water coverage over the fuel assemblies.

At Units 5 and 6, workers have successfully restored off-site power to the reactor, which had previously reached a safe, cold shutdown status.

Briefing on Fukushima Nuclear Accident (23 March 2011, 15:30 UTC)


Presentations:
Technical Briefing on Situation in Japan
Watch Video

On Wednesday, 23 March 2011, Graham Andrew, Special Adviser to the IAEA Director General on Scientific and Technical Affairs, briefed both Member States and the media on the current status of nuclear safety in Japan. His opening remarks, which he delivered at 15:30 UTC at the IAEA headquarters in Vienna, are provided below:

  • There are some positive developments related to the availability of electrical power supply to the Fukushima Daiichi nuclear power plants, although the overall situation remains of serious concern.
  • AC power is now available at Units 1, 2 and 4. Power has been restored to some instrumentation in all Units except Unit 3. At Unit 3, the main control room has lighting, but no power to its equipment or instruments. As a positive development instrumentation, as it becomes available, is providing more data that can be assessed by experts.
  • The pressure in the reactor pressure vessel and drywell of Unit 3 is stable. However, pressure has increased in both the reactor pressure vessel and the drywell of Unit 1, where seawater injection has been increased. Until heat can be removed from Unit 1, pressure tends to increase as water is injected. The reactor feed water system is being used, in addition to water injection through fire extinguisher lines.
  • Pressure readings in Unit 2 appear to be less reliable. Only limited data is available concerning the reactor pressure vessel and reactor containment vessels' integrity of Unit 2. Temperature readings in the reactor pressure vessels of Units 1 and 3 were high and of some concern. The temperature has now dropped in Unit 1 following the start of seawater injection via feed-water pipes. Indications are that the temperature at Unit 2 is stable.
  • Units 5 and 6 continue to have off-site power and remain in cold shutdown.
  • Dose rates measured in the containment vessels and suppression chambers of Units 1, 2 and 3 are available and are being studied.
  • Periodic water spraying of Units 2, 3, and 4 and the common spent fuel pool has continued.

Radiation Monitoring

The IAEA radiation monitoring team took additional measurements at distances from 30 to 73 km from the Fukushima nuclear power plant. Results from gamma dose-rate measurements in air ranged from 0.2 to 6.9 microsievert per hour. The beta-gamma contamination measurements ranged from 0.02 to 0.6 Megabecquerel per square metre.

The second IAEA monitoring team has now arrived in Japan. The two teams in Japan will continue to work closely with the Japanese authorities. Monitoring will be undertaken in the areas of Fukushima and Tokyo. Measurements will be taken to determine more precisely the actual composition of the radionuclides that have been deposited.

More data has become available from the Japanese authorities. The measurements indicate that the radiation dose rates at the Daiichi site are decreasing. Absent further releases from the site, this is to be expected as relatively short lived radionuclides such as Iodine-131 decay away. At the Daiini site, small spikes have been observed in gamma dose rate measurements; these are most likely to be the result of releases carried by the wind from the nearby Daiichi site.

The deposition of iodine-131 and caesium-137 varies across some ten Prefectures from day to day, but the trend is generally upward. In contrast, environmental radiation monitoring data in the Fukushima Prefecture outside the 20km evacuation zone, shows mostly decreasing values.

Monitoring of the marine environment is being undertaken by the Japanese Ministry of Education, Culture, Sport, Science and Technology (MEXT). High levels of iodine-131 and caesium-137 were measured close to the effluent discharge points Units 1 to 4 of Fukushima Daiichi (i.e. before dilution by the ocean). Future monitoring will cover eight locations 30 km off the coast at 10 km intervals. Results for seawater and the atmosphere above the sea should be available in the next few days. IAEA experts from the Environment Laboratories Monaco will assess this data.

Since yesterday, the IAEA has received further information from the Japanese Ministry of Health, Labour and Welfare regarding the presence of radioactivity in milk, drinking water and vegetables. The results of some samples were above the limits specified in Japanese regulations concerning limits for food and water ingestion.

In Fukushima prefecture six raw milk samples, and in Ibaraki prefecture three spinach samples, showed concentrations of Iodine-131 in excess of limits. We understand that the Prime Minister of Japan, Mr. Naoto Kan, has today issued instructions to food business operators to cease, for the time being, the distribution of, and for the public to cease the consumption of, certain leafy vegetables (e.g. spinach, komatsuna, cabbages) and any flowerhead brassicas (broccoli, cauliflower) produced in Fukushima Prefecture. The Prime Minister has ordered food business operators not to distribute, for the time being, any fresh raw milk and parsley in Ibaraki Prefecture.

We have also been advised that the Ministry of Health, Labour and Welfare has encouraged Ibaraki and Chiba Prefectures to monitor seafood products.

The Tokyo Metropolitan Water Office stated that levels of iodine-131 in tap water at a purification plant were found to be above the limits for drinking water for infants but below the level for adults. The Ministry of Health Labour and Welfare, has requested that tap water in Tokyo is not used as drinking water for infants.

So, in summary: there are some positive indications on the site; precautionary restrictions around the site on certain foodstuffs; and monitoring of the environment is continuing beyond the evacuation zone and at sea. No significant risk to human health has been identified.

Fukushima Nuclear Accident Update (23 March 2011, 01:10 UTC)


Restoring Power to Fukushima Daiichi

Without electrical power, cooling systems at Fukushima Daiichi's six reactors cannot operate. Many of the problems facing the nuclear power plant stem from the loss of electrical power at the site following the massive earthquake and tsunami on 11 March. The earthquake cut off external power to the plant and the tsunami disabled backup diesel generators.

Japanese officials have been working to restore power to the facility, and their efforts are organized in three phases.

Units 1 and 2

Reactor cooling systems at these units are severely hampered. There is suspected damage to the nuclear fuel in both units. Workers successfully connected off-site electrical supplies to a transformer at Unit 2 on 19 March and later to at least one electrical distribution panel inside the plant. Technicians are conducting diagnostic tests to determine the integrity of the reactor's electrical systems.

Japanese authorities plan to connect Unit 1 sometime after Unit 2. Because of the degraded condition of the Unit 1 reactor building, this work may take more time compared to Unit 2, the reactor building sustained significantly less damage since the earthquake struck.

Units 3 and 4

Reactor cooling systems at Unit 3 are severely hampered. There is suspected damage to the reactor's fuel, and the condition of its spent fuel pool is uncertain. Unit 4 had been shut down for routine maintenance - and all its fuel was removed to the reactor building's spent fuel pool - prior to the earthquake. There is therefore no concern about fuel in the reactor core, but considerable concern about the fuel in the spent fuel pool.

Workers are moving toward restoring electricity to both units, but their progress is uncertain.

Units 5 and 6

Both units had been shut down for routine maintenance prior to the earthquake, reducing their cooling needs somewhat, but not entirely. On 17 March operators were able to start one of the Unit 6 diesel generators. On 19 March, workers successfully connected the second diesel generator in Unit 6. The two generators were used to power cooling systems in both reactors, which then achieved a safe, cold shutdown configuration. Off-site power was restored to Unit 5 on 21 March.

Restoring external power to the power plant does not mean the reactors will immediately resume normal safety function. The earthquake and tsunami may have inflicted considerable damage in addition to knocking out electricity supplies. Since the extent of this damage (and therefore the extent of necessary repair) is unknown, it is not possible to accurately estimate a work schedule. Progress of efforts to restore power may be impaired by heavy gloves or respirators required to permit the operators to work in the reactors following the damage inflicted by the earthquake and tsunami.

As power is restored, workers will perform checks to make certain the conditions are safe to restart individual components. They will check for grounds and ensure circuits remain intact. If damage is discovered, a decision will have to be made whether to perform repairs or move on to the next component on a prioritized list. Nuclear reactors, especially safety related equipment, incorporate multiple layers of redundancy. So a problem in one component does not necessarily mean a specific safety function will be unrecoverable. It is more likely that operators will move on to the redundant equipment in an effort to determine the most intact system and focus their restoration efforts there. This process takes time.

Fukushima Nuclear Accident Update (22 March 2011, 23:15 UTC)


Summary of Conditions at Fukushima Daiichi Nuclear Power Plant

Located on the Eastern coast of Japan, the six nuclear power reactors at Daiichi are boiling water reactors (BWRs). A massive earthquake on 11 March disabled off-site power to the plant and triggered the automatic shutdown of the three operating reactors - Units 1, 2 and 3. The control rods in those units were successfully inserted into the reactor cores, ending the fission chain reaction. The remaining reactors - Units 4, 5 and 6 - had previously been shut down for routine maintenance purposes. Backup diesel generators, designed to start up after losing off-site power, began providing electricity to pumps circulating coolant to the six reactors.

Soon after the earthquake, a large tsunami washed over the reactor site, knocking out the backup generators. While some batteries remained operable, the entire site lost the ability to maintain normal reactor cooling and water circulation functions.

Here is the current status of the six reactors, based on documents and confirmed by Japanese officials (new information from 22 March in bold):

Unit 1

Coolant within Unit 1 is covering about half of the fuel rods in the reactor, and Japanese authorities believe the core has been damaged. High pressure within the reactor's containment led operators to vent gas from the containment. Later, an explosion destroyed the outer shell of the reactor building above the containment on 12 March.

There are no indications of problems with either the reactor pressure vessel or the primary containment vessel.

Efforts to pump seawater into the reactor core are continuing.

No precise information has been available on the status of the spent fuel pool.

On 18 March, Japan assigned an INES rating of 5 to this Unit. (See further information on ratings and INES scale).

On 19 March, the containment vessel pressure indication was restored.

Unit 2

Coolant within Unit 2 is covering about half of the fuel rods in the reactor, and Japanese authorities believe the core has been damaged. Following an explosion on 15 March, Japanese officials expressed concerns that the reactor's containment may not be fully intact. As of 19 March, 11:30 UTC, officials could no longer confirm seeing white smoke coming from the building. Smoke had been observed emerging from the reactor earlier. White "smoke/vapour" was observed again from 9:22 UTC on 21 March and diminished to nearly invisible by 22:11 UTC the same day. During the time of smoke emission, an increase in radiation dose rates was reported at 9:30 UTC 21 March. TEPCO then ordered an evacuation of plant personnel, though workers returned as of 00:00 UTC 22 March.

Efforts to pump seawater into the reactor core are continuing.

On 20 March, workers began pumping 40 tonnes of seawater into the spent fuel pool. Spent fuel temperature remains relatively stable with readings between 49°C and 53°C.

Restoration work to return power to all units continues, with progress at Unit 2 the most advanced. A distribution panel (power center) of Unit 2 has been connected to off-site electricity supply, and individual components in the unit are being checked prior to being energized.

On 18 March, Japan assigned an INES rating of 5 to this Unit.

Unit 3

Coolant within Unit 3 is covering about half of the fuel rods in the reactor, and Japanese authorities believe the core has been damaged. High pressure within the reactor's containment led operators to vent gas from the containment. Later, an explosion destroyed the outer shell of the reactor building above the containment on 14 March. Indicated containment pressure has stabilized over the past 24 hours.

Following the explosion, Japanese officials expressed concerns that the reactor's containment may not be fully intact. White smoke has been seen emerging from the reactor, but on 19 March it appeared to be less intense than in previous days. Grey smoke was observed on 21 March in the southeast corner of Unit 3 from 6:55 UTC. After two hours this smoke turned to a white color and gradually diminished. By 22:11 21 March, the smoke was observed to be "ceasing." As reported under the Unit 2 update, during the time of smoke emission, an increase in radiation dose rates was reported at 9:30 UTC on 21 March. TEPCO then ordered an evacuation of plant personnel, though workers returned as of 00:00 UTC 22 March.

Efforts to pump seawater into the reactor core are continuing. Of additional concern at Unit 3 is the condition of the spent fuel pool in the building. There are indications that there is inadequate cooling water level in the pool, and Japanese authorities have addressed the problem by dropping water from helicopters into the building and spraying water from trucks. Spraying from trucks continued on 20 March. There is no data on the temperature of the water in the pool.

On 18 March, Japan assigned an INES rating of 5 to this Unit.

Unit 4

All fuel from Unit 4 had been removed from the reactor core for routine maintenance before the earthquake and placed into the spent fuel pool. The building's outer shell was damaged on 14 March, and there have been two reported fires - possibly including one in the area of the spent fuel pool on 15 March - that were extinguished spontaneously.

Authorities remain concerned about the condition of the spent fuel pool, and Japanese Self Defence Forces began spraying water into the building on 20 March. As of 8:17 UTC on 22 March, a concrete pump was pumping water into the spent fuel pool at a rate of 50 tonnes per hour. The reported plan was to pump water at this rate for 3 hours.

On 18 March, Japan assigned an INES rating of 3 to this site.

Units 5 and 6

Shut down for routine maintenance before the earthquake, both reactors achieved cold shutdown on 20 March. The reactors are now in a safe mode, with cooling systems stable and under control, and with low temperature and pressure within the reactor.

Instrumentation from both spent fuel pools had shown gradually increasing temperatures over the past few days. Officials configured two diesel generators at Unit 6 to power cooling and fresh-water replenishment systems in the spent fuel pools and cores of Units 5 and 6. As of 20 March, temperatures in both pools had decreased significantly. /p>

Workers have opened holes in the roofs of both buildings to prevent the possible accumulation of hydrogen, which is suspected of causing explosions at other units.

Fukushima Nuclear Accident Update (22 March 2011, 18:00 UTC)


Spent Fuel Pools at Fukushima Daiichi Nuclear Power Plant - Updated

Spent fuel removed from a nuclear reactor is highly radioactive and generates intense heat. This irradiated fuel needs to be actively cooled for one to three years in pools that cool the fuel, shield the radioactivity, and keep the fuel in the proper position to avoid fission reactions. If the cooling is lost, the water can boil and fuel rods can be exposed to the air, possibly leading to severe damage and a large release of radiation.

Nuclear power plants must replace fuel every one to two years, and the Fukushima Daiichi reactors typically remove about 25 percent of the reactor's fuel - to be replaced with fresh, or unirradiated, fuel - during each refuelling outage. The spent fuel, which is hottest immediately after it is removed from the reactor, is placed in the spent fuel pool until it is cool enough to be moved to longer-term storage.

The concern about the spent fuel pools at Fukushima Daiichi is that the capability to cool the pools has been compromised. See diagram below for location of the pool in each reactor building.

Elevated radiation measurements at the site may be partially of the result of uncovered or overheated spent fuel.

Number of Fuel Assemblies in Cooling Pools at Fukushima Daiichi
(Reported 17 March by Japan's Ministry of Economy, Trade and Industry)

Capacity Irradiated Fuel Assemblies Unirradiated Fuel Assemblies Most Recent Additions of Irradiated Fuel
Unit 1 900 292 100 March 2010
Unit 2 1,240 587 28 Sept 2010
Unit 3 1,220 514 52 June 2010
Unit 4 1,590 1,331 204 Nov 2010
Unit 5 1,590 946 48 Jan 2011
Unit 6 1,770 876 64 Aug 2010

Here is a summary of spent fuel conditions at Fukushima Daiichi nuclear power plant, based on documents and confirmed by Japanese officials (new information in bold):

Unit 1

Unit 1 experienced an explosion on 12 March that destroyed the outer shell of the building's upper floors. No precise information has been available on the status of the spent fuel pool.

Unit 2

Precise information on the status of the spent fuel pool was unavailable in the days following the earthquake, but Japan's Nuclear and Industrial Safety Agency began to release temperature data on 20 March:

20 March, 23:00 UTC: 49 °C
21 March, 05:25 UTC: 50 °C
21 March, 21:20 UTC: 51 °C
22 March, 02:20 UTC: 53 °C
22 March, 06:30 UTC: 50 °C

Workers conducted an operation to spray 40 tonnes of seawater to the spent fuel pool on 20 March.

Unit 3

Unit 3 experienced an explosion on 14 March that destroyed the outer shell of the building's upper floors. The blast may have damaged the primary containment vessel and the spent fuel pool. Concerned by possible loss of water in the pool, authorities began spraying water into the building in an effort to replenish water levels. First, helicopters dropped seawater on 17 March, and every day since then, including 21 March, emergency workers have sprayed water from fire trucks and other vehicles, so far spraying at least 3,742 tonnes.

Unit 4

This reactor was shut down 30 November 2010 for routine maintenance, and all the fuel assemblies were transferred from the reactor to the spent fuel pool, before the 11 March earthquake. The heat load in this pool is therefore larger than the others.

On 14 March, the building's upper floors were severely damaged, possibly causing a reduction of cooling capability in the spent fuel pool. Emergency workers began spraying water into the building on 20 March, and have continued daily since then, so far spraying at least 255 tonnes.

Units 5 and 6

Instrumentation at these reactors began to indicate rising temperatures at their spent fuel pools starting on 14 March. Three days later, Japanese technicians successfully started an emergency diesel generator at Unit 6, which they used to provide power to basic cooling and fresh-water replenishment systems. Workers created holes in the rooftops of both buildings to prevent any hydrogen accumulation, which is suspected of causing earlier explosions at Units 1 and 3.

A second generator came online on 18 March, and the next day, the higher-capability Residual Heat Removal system recovered full function. Temperatures in the spent fuel pools of Units 5 and 6 have gradually returned to significantly lower temperatures (See graph below).

Common Use Spent Fuel Pool

In addition to pools in each of the plant's reactor buildings, there is another facility - the Common Use Spent Fuel Pool - where spent fuel is stored after cooling at least 18 months in the reactor buildings. This fuel is much cooler than the assemblies stored in the reactor buildings. Japanese authorities confirmed as of 18 March that fuel assemblies there were fully covered by water, and the temperature was 57 °C as of 20 March, 00:00 UTC. Workers sprayed water over the pool on 21 March for nearly five hours, and the Nuclear and Industrial Safety Agency reported that the pool temperature had risen to 61 °C as of 21 March, 07:30 UTC.

Fukushima Nuclear Accident Update (22 March 2011, 16:45 UTC)


Seawater Monitoring - Updated

Japanese authorities have reported that the Tokyo Electric Power Company has detected radioactive materials in seawater at one location near the Southern discharge canal at the Fukushima Daiichi nuclear power plant. Samples taken included levels of iodine-131, cesium-134, and cesium-137.

To study a larger area of the marine environment, the Japan Agency for Marine-Earth Science and Technology (JAMSTEC) plans to measure radioactivity around the plant from 22-23 March. Seawater will be collected from eight locations, and the Japan Atomic Energy Agency plans to analyse the samples and release results on 24 March. The analysis will include radionuclide concentrations found in sea water and dose rate in the air. The IAEA will continue to follow this information.

IAEA Briefing on Fukushima Nuclear Emergency (22 March 2011, 15.30 UTC)


Presentations:
IAEA Briefing on Fukushima Nuclear Emergency
Watch Video

On Tuesday, 22 March 2011, Graham Andrew, Special Adviser to the IAEA Director General on Scientific and Technical Affairs, briefed both Member States and the media on the current status of nuclear safety in Japan. His opening remarks, which he delivered at 15:30 UTC at the IAEA headquarters in Vienna, are provided below:

1. Current Situation

There continue to be some improvements at the Fukushima Daiichi nuclear power plant, but the overall situation remains very serious. High levels of contamination have been measured in the locality of the plant.

On the Fukushima site the highest concern remains the spent fuel in the storage ponds of each reactor unit, particularly Unit 4. Reactor Units1-3 remain of concern, in particular Unit 2.

We have not received validated information for some time related to the containment integrity of Unit 1 so we are concerned that we do not know its exact status. Grey smoke was observed from Unit 3 which led to the evacuation of plant personnel for several hours yesterday due to elevated dose rates. In addition, white smoke or vapour was observed from Unit 2. Efforts continue in Unit 2 to connect AC to pumps etc. Work for the recovery of off-site power supply to Units 3 and 4 is also proceeding.

Seawater is being injected into the reactor vessels of Units 1, 2 and 3. Water is being sprayed periodically into the spent fuel pools at Units 2, 3 and 4 but no information is available for the spent fuel pool of Unit 1. The Agency still lacks data on water levels and temperatures in the spent fuel pools at Units 1, 3 and 4.

There have been some positive developments concerning Units 5 and 6 that are in cold shutdown: off-site power is now being used in Unit 5; the pressure of the reactor pressure vessel of both units has decreased; and water is being injected in to the reactor pressure vessel, as needed.

2. Radiation Monitoring

IAEA monitoring of gamma dose rates and beta-gamma contamination has continued over the last 24 hours. This has been carried out together with the Japanese authorities to facilitate the comparison of results.

The IAEA took measurements at additional locations between 35 to 68 km from the Fukushima plant. The dose-rate results ranged from 0.8 to 9.1 microsieverts per hour. The beta-gamma contamination measurements ranged from 0.08 to 0.9 MBq per square metre. More precise interpretation of the results will be possible based on measurements to be made of the composition of the radioactive material that has been released.

In the coming days the IAEA will have two monitoring teams in Japan. One team will be in the Fukushima area and a separate team will undertake monitoring in Tokyo and the surrounding area.

The Agency continues to receive data confirming high levels of radioactivity in food, notably spinach, in samples taken from 37 locations in the vicinity of five cities south of the Fukishima site. This indicates that in four Prefectures some food products are above permissible levels. High levels of both Iodine-131 and Caesium-137 have been measured by the Japanese authorities in spinach and some other fresh vegetables, together with Iodine-131 in milk. However, as reported yesterday, distribution of food from the areas affected has been restricted. The Japanese authorities are monitoring the situation in the rest of the country. Further monitoring data will be provided by Japan to the IAEA/FAO on an ongoing basis.

Japan's Nuclear and Industrial Safety Agency (NISA) has announced that contamination has been found in sea water samples taken close to the outlet of the Fukushima Daiichi plant. We have been informed by NISA about plans to monitor the marine environment.

Fukushima Nuclear Accident Update (22 March 2011, 04:15 UTC)


Japanese authorities have reported that they will measure radioactivity in the marine environment around the Fukushima Daiichi nuclear power plant. The monitoring will be conducted from 22-23 March by the Japan Agency for Marine-Earth Science and Technology (JAMSTEC). Sea water sampling from eight locations will be sampled and analysed by the Japan Atomic Energy Agency (JAEA), and results will be provided on 24 March. The analysis will include radionuclide concentrations found in sea water and dose rate. The IAEA will continue to follow this information.

Fukushima Nuclear Accident Update (21 March 2011, 23:15 UTC)


Status of Fukushima Daiichi Nuclear Power Plant

Japanese authorities have notified the IAEA that efforts to restore power for the Fukushima Daiichi nuclear plant are on-going. As of 19 March at 21:46 UTC, the power centre at Unit 2 had received electricity. Work to restore electricity to Units 3 and 4 is continuing.

White "smoke" was reported seen emanating from Unit 2 on 21 March at 9:22 UTC. Grayish smoke was reported seen emanating from unit 3 at 6:55 on 21 March, and this was reported to have "died down" two hours later. All workers at Units 1 through 4 evacuated after the smoke at Unit 3 was seen. The IAEA is seeking further information at this time on the status of workers at the site.

Japanese authorities have also reported that water has been sprayed over the Common Spent Fuel Pool; this started on 21 March at 1:37 UTC. The IAEA is seeking further information on this development and will report further as updates are received from Japan.

Fukushima Nuclear Accident Update (21 March 2011, 15:30 UTC)


Presentation:
Technical Briefing on Situation in Japan

On Monday, 21 March 2011, Graham Andrew, Special Adviser to the IAEA Director General on Scientific and Technical Affairs, briefed both Member States and the media on the current status of nuclear safety in Japan. His opening remarks, which he delivered at 15:30 UTC at the IAEA headquarters in Vienna, are provided below:

"1. Current Situation

We are seeing some steady improvements, but the overall situation at the Fukushima Daiichi nuclear power plant remains very serious. High levels of contamination have been measured in the locality of the plant.

The restoration of electrical power to Unit 2, which we reported yesterday, is good news. AC power is available and an electrical load check to pumps, etc. is currently on-going. Work on the restoration of off-site power to Units 3 and 4 is also underway.

Seawater is still being injected into the reactor pressure vessels of Units 1, 2 and 3.

Pressure in the reactor pressure vessel and the containment vessel drywell at Unit 3, which had been rising yesterday, has again fallen.

Water is being sprayed periodically into the spent fuel pools at Units 2, 3 and 4. The Agency still lacks data on water levels and temperatures in the spent fuel pools at Units 1, 2, 3 and 4.

Following the restoration of cooling at Units 5 and 6, temperatures in the spent fuel pools continue to decline.

2. Radiation Monitoring

As I reported yesterday, the IAEA radiation monitoring team took measurements at distances from 56 to 200 km from the Fukushima nuclear power plant. At two locations in Fukushima Prefecture gamma dose rate and beta-gamma contamination measurements have been repeated. These measurements showed high beta-gamma contamination levels. Measurements by the IAEA and the Japanese authorities were taken at the same time and locations. The Japanese and independent IAEA measurements gave comparable results.

Measurement of gamma dose rate and beta-gamma contamination were taken on 20 March at more locations. The dose-rate results ranged from 2-160 microsieverts per hour, which compares to a typical natural background level of around 0.1 microsieverts per hour. High levels of beta-gamma contamination have been measured between 16-58 km from the plant. Available results show contamination ranging from 0.2-0.9 MBq per square metre.

Further measurements are needed to assess possible contamination beyond the area currently monitored - both closer to the facility and further way. We have no contamination measurements showing that that contamination levels are high at greater distances than 58 km from the plant, but this cannot be excluded.

I have no further information available regarding the measurement of alpha radiation. As I reported yesterday, from the measurements taken within the evacuation zone (20 km), no significant alpha radiation had been detected at that time.

In the coming days, the IAEA monitoring team will continue to take measurements in the Fukushima prefecture. We are seeking data from Japan on radioactivity contamination measurements for the rest of Japan.

Some results on the monitoring of foodstuffs have been made available by Japan to the IAEA and FAO. Results provided recently by the Japanese authorities range up to 55 000 Bq per kg of I-131 in samples of Spinach taken in in the Ibaraki Prefecture. These high values are significantly above Japanese limits for restricting food consumption (i.e. 2 000 Bq/kg). I understand that the Japanese Government is actively considering relevant precautionary measures and has instructed four Prefectures (Ibaraki, Totigi, Gunma, Fukushima) to refrain, for the time being, from distributing two types of vegetables (spinach and kakina) from these Prefectures and milk from Fukshima.

3. Agency Activities

Watch Video

The Director General briefed the Board of Governors today on the outcome of his visit to Tokyo."

Fukushima Nuclear Accident Update (20 March 2011, 21:00 UTC)


Summary of Conditions at Fukushima Daiichi Nuclear Power Plant

Located on the Eastern coast of Japan, the six nuclear power reactors at Daiichi are boiling water reactors (BWRs). A massive earthquake on 11 March disabled off-site power to the plant and triggered the automatic shutdown of the three operating reactors - Units 1, 2 and 3. The control rods in those Units were successfully inserted into the reactor cores, ending the fission chain reaction. The remaining reactors - Units 4, 5 and 6 - had previously been shut down for routine maintenance purposes. Backup diesel generators, designed to start up after losing off-site power, began providing electricity to pumps circulating coolant to the six reactors.

Soon after the earthquake, a large tsunami washed over the reactor site, knocking out the backup generators. While some batteries remained operable, the entire site lost the ability to maintain normal reactor cooling and water circulation functions.

Here is the current status of the six reactors, based on documents and confirmed by Japanese officials (new information from 20 March in bold):

Unit 1

Coolant within Unit 1 is covering about half of the fuel rods in the reactor, and Japanese authorities believe the core has been damaged. High pressure within the reactor's containment led operators to vent gas from the containment. Later, an explosion destroyed the outer shell of the reactor building above the containment on 12 March.

There are no indications of problems with either the reactor pressure vessel or the primary containment vessel.

Efforts to pump seawater into the reactor core are continuing.

No precise information has been available on the status of the spent fuel pool.

On 18 March, Japan assigned an INES rating of 5 to this Unit.

→ Further information on ratings and INES scale.

On 19 March, the containment vessel pressure indication was restored.

Unit 2

Coolant within Unit 2 is covering about half of the fuel rods in the reactor, and Japanese authorities believe the core has been damaged. Following an explosion on 15 March, Japanese officials expressed concerns that the reactor's containment may not be fully intact. As of 19 March, 11:30 UTC, officials could no longer confirm seeing white smoke coming from the building. Smoke had been observed emerging from the reactor earlier.

Efforts to pump seawater into the reactor core are continuing.

No precise information has been available on the status of the spent fuel pool. On 20 March, workers began pumping 40 tonnes of seawater into the spent fuel pool.

On 18 March, Japan assigned an INES rating of 5 to this Unit.

Unit 3

Coolant within Unit 3 is covering about half of the fuel rods in the reactor, and Japanese authorities believe the core has been damaged. High pressure within the reactor's containment led operators to vent gas from the containment. Later, an explosion destroyed the outer shell of the reactor building above the containment on 14 March.

Following the explosion, Japanese officials expressed concerns that the reactor's containment may not be fully intact. White smoke has been seen emerging from the reactor, but on 19 March it appeared to be less intense than in previous days.

Efforts to pump seawater into the reactor core are continuing.

Of additional concern at Unit 3 is the condition of the spent fuel pool in the building. There are indications that there is inadequate cooling water level in the pool, and Japanese authorities have addressed the problem by dropping water from helicopters into the building and spraying water from trucks. Spraying from trucks continued on 20 March. There is no data on the temperature of the water in the pool.

On 18 March, Japan assigned an INES rating of 5 to this Unit.

Unit 4

All fuel from Unit 4 had been removed from the reactor core for routine maintenance before the earthquake and placed into the spent fuel pool. The building's outer shell was damaged on 14 March, and there have been two reported fires - possibly including one in the area of the spent fuel pool on 15 March - that were extinguished spontaneously.

Authorities remain concerned about the condition of the spent fuel pool, and Japanese Self Defence Forces began spraying water into the building on 20 March.

On 18 March, Japan assigned an INES rating of 3 to this site.

Units 5 and 6

Shut down for routine maintenance before the earthquake, both reactors achieved cold shutdown on 20 March. The reactors are now in a safe mode, with cooling systems stable and under control, and with low temperature and pressure within the reactor.

Instrumentation from both spent fuel pools had shown gradually increasing temperatures over the past few days. Officials configured two diesel generators at Unit 6 to power cooling and fresh-water replenishment systems in the spent fuel pools and cores of Units 5 and 6. As of 20 March, temperatures in both pools had decreased significantly.

Workers have opened holes in the roofs of both buildings to prevent the possible accumulation of hydrogen, which is suspected of causing explosions at other units.

Restoration of Grid

Progress has been achieved in restoring external power to the nuclear power plant, although it remains uncertain when full power will be available to all reactors. Off-site electrical power has been connected to an auxiliary transformer and distribution panels at Unit 2. Work continues toward energizing specific equipment within Unit 2.

Evacuation

Japanese authorities have informed the IAEA that the evacuation of the population from the 20-kilometre zone around Fukushima Daiichi has been successfully completed. Japanese authorities have also advised people living within 30 kilometres of the plant to remain inside.

Iodine

On 16 March, Japan's Nuclear Safety Commission recommended local authorities to instruct evacuees leaving the 20-kilometre area to ingest stable (not radioactive) iodine. The pills and syrup (for children) had been prepositioned at evacuation centers. The order recommended taking a single dose, with an amount dependent on age:

Baby 12.5 mg
1 mo.-3 yrs. 25 mg
3-13 yrs. 38 mg
13-40 yrs. 76 mg
40+ yrs. Not necessary

Radiation Measurements

Radiation levels near Fukushima Daiichi and beyond have elevated since the reactor damage began. However, dose rates in Tokyo and other areas outside the 30-kilometre zone remain below levels which would require any protective action. In other words they are not dangerous to human health.

Dose rates have been provided by Ministry of Education, Culture, Sport, Science and Technology for 47 cities and town representing a comprehensive nationwide monitoring network. The data set covers the period from 15 March, 08:00 UTC to 20 March, 17:00 UTC with an hourly sampling frequency. No significant changes of dose rates have been observed if compared to previous day data.

At the Fukushima Daiichi nuclear plant, radiation levels spiked three times since the earthquake, but have stabilized since 16 March at levels which are, although significantly higher than the normal levels, within the range that allows workers to continue onsite recovery measures. Two new on-site environmental monitoring locations have been added to the monitoring network.

Radionuclides in Foodstuffs and Water

The IAEA has received information from the Japanese Ministry of Health, Labor and Welfare regarding the presence of Iodine-131 in three milk samples tested in the town of Kawamata. The concentration is reported to be above allowed levels. Cesium-137 was detected in one sample, though in concentration below allowed levels.

In the Ibaraki prefecture, Iodine-131 and Cesium-137 have been detected in leaf vegetables such as spring onions and spinach. Some of the samples have been reported to be above the levels allowed by the Japanese food hygiene law for emergency monitoring criteria for intake of vegetables.

According to the Nuclear Safety Division, Ministry of Education, Culture, Sports, Science and Technology (MEXT) analysis for Iodine-131 and Cesium-137 in tap water from 46 locations yielded the majority of samples as non-detects. Only six out of 46 exhibited any iodine-131, though the concentration was reported to be below levels allowed by the Japanese food hygiene law for emergency monitoring criteria for drinking water.


Fukushima Daiichi Summary Table - Units 1-6 (20 March 2011, 21:00 UTC):
  • Legend
  • No Immediate Concern
  • Concern
  • Severe Condition
Unit 1 2 3 4 5 6
Power (MWe/th) 460/1380 784/2381 784/2381 784/2381 784/2381 1100/3293
Type of Reactor BWR-3 BWR-4 BWR-4 BWR-4 BWR-4 BWR-5
Status at Time of Event In service - auto shutdown following earthquake Shut down for outage before earthquake
Core and Fuel Damaged No fuel rods Cold shutdown
Containment Integrity No damage reported Damage suspected No information Outage configuration No damage expected
Off-site Power Substation connected Power center (in Unit) connected Not available Not available
Diesel Generators Not available Two emergency diesel generators powering Units 5 and 6
Building Severe damage Slight damage Severe damage No damage reported
Water Level in Reactor Pressure Vessel About half of fuel assembly (stable) Outage configuration Above fuel
Pressure of Reactor Pressure Vessel Stabilised Unreliable data Elevated Outage configuration Stabilised Stabilised
Containment Pressure Drywell Stable Stable Elevated Outage configuration No information
Water Injection to Reactor Pressure Vessel Sea water Sea water Sea water Outage configuration Freshwater injection in progress
Water Injection to Containment Vessel Not available Not necessary
Spent Fuel Pool Temperature No information Spraying from outside Spraying from outside Spraying from outside Cooling restored

IAEA Briefing on Fukushima Nuclear Emergency (20 March 2011, 15.30 UTC)


Presentations:
Technical Briefing on Situation in Japan
Watch Video

On Sunday, 20 March 2011, Graham Andrew, Special Adviser to the IAEA Director General on Scientific and Technical Affairs, briefed both Member States and the media on the current status of nuclear safety in Japan. His opening remarks, which he delivered at 15:30 UTC at the IAEA headquarters in Vienna, are provided below:

1. Current Situation

There have been some positive developments in the last 24 hours, but the overall situation at the Fukushima Daiichi nuclear power plant remains very serious.

Efforts to restore electrical power to the site continue. Off-site electrical power has been connected to the local substation for Unit 2 today. Work is continuing under difficult conditions to connect power from the substation to the reactor building. Seawater is still being injected into the reactor pressure vessels of Units 1, 2 and 3. Water injection is not needed for Unit 4 as the reactor is in outage.

White "smoke" or vapour from Unit 3 is still being observed, but it is less intense than on previous days. Spraying of the reactor building with water is in progress.

Following an initial rise in pressure in the Unit 3 reactor pressure vessel, plans were made to vent the vessel should it become necessary. However, from information recently provided by NISA they have decided not to vent as the vessel pressure has started to reduce.

The situation in the reactor spent fuel pools is relatively stable, but is still of concern. Spraying of water into the pool of Unit 4 started yesterday. The Agency still lacks data on water levels and temperatures at the spent fuel pools at Units 1, 2, 3 and 4.

A positive development is that cooling has been restored to the reactor pressure vessels in Units 5 and 6. Temperatures in the spent fuel pools at these two units, which had been rising in the last few days, have now fallen significantly to around 40 degrees centigrade from a maximum of about 69 degrees yesterday. Two diesel generators, one for each Unit, are providing electricity.

2. Radiation Monitoring

Radiation levels in major Japanese cities have not changed significantly since yesterday and remain below those which are dangerous to human health.

The IAEA radiation monitoring team took additional measurements yesterday between Tokyo and locations up to 150 km from the Fukushima site. Dose rates were typically a few microsieverts per hour compared to a typical background level of around 0.1 microsieverts per hour.

From the measurements taken within the exclusion zone, no significant alpha radiation has been detected so far.

This morning, we received additional data from the Agency's monitoring team which indicated contamination on the ground at a location 50 to 70 km from the Fukushima site. The team will make confirmatory measurements tomorrow at the same locations to help validate the initial results. Grass and other samples have also been taken by the team from various locations in the Fukushima Prefecture for analysis. In the coming days, the IAEA monitoring team plans to take measurements at the same locations monitored by the Japanese authorities. This will assist in the validation of measurements. The IAEA is sending additional monitoring experts to Japan to supplement its capabilities in the field.

Some results on the monitoring of foodstuffs have been made available by Japan to the IAEA and FAO. We can confirm measurements indicating that, in some areas, Iodine-131 in milk and in freshly grown leafy vegetables, such as spinach and spring onions, is significantly above the levels set by Japan for restricting consumption of these food products.

3. Agency Activities

The Director General has returned to Vienna and will brief the Board of Governors on Monday on the outcome of his visit to Tokyo.

Fukushima Nuclear Accident Update (20 March 2011, 16:20 UTC)


Japanese authorities have notified the IAEA of progress at the Fukushima Daiichi nuclear power plant. Workers today have successfully placed reactor Unit 5 (at 05:30 UTC) and 6 (at 10:27 UTC) into cold shutdown.

This means that the reactors are in a safe mode, with cooling systems stable and under control, and with low temperature and pressure within the reactor.

Officials are continuing efforts to restore plant systems at Daiichi Units 1-3.

Unit 4 had been shut down for maintenance, with all its fuel removed from the reactor core, before the 11 March earthquake.

Eight other reactors at the Fukushima Daini, Onagawa, and Tokai nuclear power plants were shut down automatically after the earthquake and all are now in cold shutdown.

Fukushima Nuclear Accident Update (20 March 2011, 14:00 UTC)


Spent Fuel Pools at Fukushima Daiichi Nuclear Power Plant - Updated

Spent fuel removed from a nuclear reactor is highly radioactive and generates intense heat. This fuel needs to be actively cooled for one to three years in pools that cool the fuel, shield the radioactivity, and keep the fuel in the proper position to avoid fission reactions. If the cooling is lost, the water can boil and fuel rods can be exposed to the air, possibly leading to severe damage and a large release of radiation.

The concern about the spent fuel pools at Fukushima Daiichi is that sources of power to cool the pools have been compromised. (See diagram below for location of the pool in each reactor building.)

Elevated radiation measurements at the site may be partially of the result of uncovered or overheated spent fuel.

Here is a summary of spent fuel conditions at Fukushima Daiichi nuclear power plant, based on documents and confirmed by Japanese officials (new information in bold):

Unit 1

Unit 1 experienced an explosion on 12 March that destroyed the outer shell of the building's upper floors. No precise information has been available on the status of the spent fuel pool.

Unit 2

No precise information has been available on the status of the spent fuel pool. Authorities began adding 40 tonnes of seawater to the spent fuel pool on 20 March.

Unit 3

Unit 3 experienced an explosion on 14 March that destroyed the outer shell of the building's upper floors. The blast may have damaged the primary containment vessel and the spent fuel pool. Concerned by possible loss of water in the pool, authorities began spraying water into the building in an effort to replenish water levels. First, helicopters dropped seawater on 17 March, and every day since then, including today, emergency workers have sprayed water from fire trucks and other vehicles.

Unit 4

This reactor was shut down 30 November 2010 for routine maintenance, and all the fuel assemblies were transferred from the reactor to the spent fuel pool, before the 11 March earthquake. The heat load in this pool is therefore larger than the others.

On 14 March, the building's upper floors were severely damaged, possibly causing a reduction of cooling capability in the spent fuel pool. Emergency workers began spraying water into the building today.

Unit 5 and 6

Instrumentation at these reactors began to indicate rising temperatures at their spent fuel pools starting on 14 March. Three days later, Japanese technicians successfully started an emergency diesel generator at Unit 6, which they used to provide power to basic cooling and fresh-water replenishment systems. Workers created holes in the rooftops of both buildings to prevent any hydrogen accumulation, which is suspected of causing earlier explosions at Units 1 and 3.

A second generator came online on 18 March, and the next day, the higher-capability Residual Heat Removal system recovered full function. Temperatures in the spent fuel pools of Units 5 and 6 have gradually returned to significantly lower temperatures. (See graph at left.)

Common Use Spent Fuel Pool

In addition to pools in each of the plant's reactor buildings, there is another facility - the Common Use Spent Fuel Pool - where spent fuel is stored after cooling at least 18 months in the reactor buildings. This fuel is much cooler than the assemblies stored in the reactor buildings. Japanese authorities have confirmed that fuel assemblies there are fully covered by water, and the temperature was 57 °C as of 20 March, 00:00 UTC.

IAEA Briefing on Fukushima Nuclear Emergency (19 March 2011, 14:00 UTC)


Presentation:
Technical Briefing on Situation in Japan
Watch video

On Saturday, 19 March 2011, Graham Andrew, Special Adviser to the IAEA Director General on Scientific and Technical Affairs, briefed both Member States and the media on the current status of nuclear safety in Japan. His opening remarks, which he delivered at 14:00 UTC at the IAEA headquarters in Vienna, are provided below:

1. Current Situation

The situation at the Fukushima Daiichi nuclear power plants is similar to that which I described yesterday.

Efforts to restore electrical power to the site continue. It is hoped that power will be restored to Unit 2 today, which will then act as a hub for restoring power to Unit 1. However, we do not know if the water pumps have been damaged and if they will work when power is restored.

Seawater is still being injected into the reactor pressure vessels of Units 1 and 2 and additional fire trucks have arrived, reinforcing the operation to spray water into the Unit 3 reactor building.

We still lack reliable validated data on water levels and temperatures at the spent fuel pools at Units 3 and 4.

Temperatures at the spent fuel pools in Units 5 and 6 have risen in the past few days but this does not give rise to immediate concern. Water continues to be circulated within the reactor pressure vessels and the spent fuel ponds at both units.

A second diesel generator is providing power for cooling at Units 5 and 6. We have been informed that holes have been made in the roof of the reactor building at Units 5 and 6 to avoid the risk of a hydrogen explosion.

2. Radiation Monitoring

Radiation levels in major Japanese cities have not changed significantly since yesterday.

The IAEA radiation monitoring team took measurements at seven different locations in Tokyo and in the Kanagawa and Chiba Prefectures. Dose rates were well below those which are dangerous to human health.

The monitoring team are now on their way to Aizu Wakamatsu City, which is 97 km west of the Fukushima nuclear power plant. They have just provided initial measurements from three additional locations.

Measurements made by Japan in a number of locations have shown the presence of radionuclides - ie isotopes such as Iodine-131 and Caesium-137 - on the ground.

This has implications for food and agriculture in affected areas. The IAEA and the UN Food and Agriculture Organization (FAO) are consulting with the Japanese authorities on measures being taken in these areas related to food and agriculture.

The Japanese Ministry of Health, Labour and Welfare has announced that radiation levels that exceeded legal limits had been detected in milk produced in the Fukushima area and in certain vegetables in Ibaraki. They have requested the Bureau of Sanitation at the Fukishima Prefectural Office, after conducting an investigation of the relevant information, to take necessary measures, such as identifying the provider of these samples and places where the same lots were distributed and banning sales based on the Food Hygiene Law. (Note: The text originally read out at the briefing was: "The Japanese Ministry of Health, Labour and Welfare informed the Agency that radiation levels exceeding legal limits had been detected in milk produced in the Fukushima area and in certain vegetables in Ibaraki. The Ministry ordered protective measures including a ban on sales of these products." An oral correction was made during the media briefing.)

We now have continuous online access to data from CTBTO radionuclide monitoring stations, which is being evaluated by Agency dosimetry specialists.

As far as the Fukushima Daini nuclear power plant is concerned, there is no record of any incidents or radiation releases at the site. Present elevated radiation levels at the Daini site are attributed by Japan to events at the Daiichi nuclear power plant.

3. Agency Activities

The Director General has left Tokyo for Vienna after meetings with senior government leaders and officials from the plant operator TEPCO.

As you know, he plans to brief the Board of Governors on Monday on the outcome of his trip.

Fukushima Nuclear Accident Update (19 March 2011 12:00 UTC) - Corrected


Contamination in Food Products around Fukushima

(Please note correction posted 19 March at 15:30 UTC in bold in text below. Apologies for the inconvenience.)

The Japanese Ministry of Health, Labour and Welfare has confirmed the presence of radioactive iodine contamination in food products measured in the Fukushima Prefecture, the area around the Fukushima Daiichi nuclear power plant. According to the latest data, the food products were measured from 16-18 March and indicated the presence of radioactive iodine. To date, no other radioactive isotopes have been shown to increase in the analysis of food products around Fukushima.

Though radioactive iodine has a short half-life of about 8 days and decays naturally within a matter of weeks, there is a short-term risk to human health if radioactive iodine in food is absorbed into the human body. If ingested, it can accumulate in and cause damage to the thyroid. Children and young people are particularly at risk of thyroid damage due to the ingestion of radioactive iodine.

Japanese authorities have implemented two critical measures to counter the contamination of food products by radioactive iodine. First, on 16 March, Japan's Nuclear Safety Commission recommended local authorities to instruct evacuees leaving the 20-kilometre area to ingest stable (not radioactive) iodine. As an established method of prevention, the ingestion of stable iodine can help to prevent the accumulation of radioactive iodine in the thyroid. Stable iodine pills and syrup (for children) have been made available at evacuation centres. Second, the Ministry of Health, Labour and Welfare has requested an investigation into the possible stop of sales of food products from the Fukushima Prefecture.

The IAEA has passed this information to the Food and Agricultural Organization of the United Nations (FAO) and the World Health Organization (WHO) and will continue to report on this development.

According to materials on its website, the FAO is prepared to respond upon request from the Government of Japan in the following areas:

  • Assessing radioactive contamination of the agricultural environment, especially foods;
  • Providing technical advice and determining appropriate medium- and long-term measures for agriculture - including soil, land, forests, crops, fisheries, animal health and welfare and food safety; and
  • Facilitating international trade of foods, including agricultural produce.

The IAEA continues to gather information on this development and will report further as events warrant.

Fukushima Nuclear Accident Update (19 March 2011, 4:30 UTC)


Summary of Conditions at Fukushima Daiichi Nuclear Power Plant

Located on the Eastern coast of Japan, the six nuclear power reactors at Daiichi are boiling water reactors (BWRs). A massive earthquake on 11 March severed off-site power to the plant and triggered the automatic shutdown of the three operating reactors - Units 1, 2, and 3. The control rods in those units were successfully inserted into the reactor cores, ending the fission chain reaction. The remaining reactors - Units 4, 5, and 6 - had previously been shut down for routine maintenance purposes. Backup diesel generators, designed to start up after losing off-site power, began providing electricity to pumps circulating coolant to the six reactors.

Soon after the earthquake, a large tsunami washed over the reactor site, knocking out the backup generators. While some batteries remained operable, the entire site lost the ability to maintain proper reactor cooling and water circulation functions.

Here is the current status of the six reactors, based on documents and confirmed by Japanese officials (new information in bold):

Unit 1

Coolant within Unit 1 is covering about half of the fuel rods in the reactor, leading to fuel damage. High pressure within the reactor's containment led operators to vent gas from the containment. Later, an explosion destroyed the outer shell of the reactor building above the containment on 12 March.

There are no indications of problems with either the reactor pressure vessel or the primary containment vessel.

Efforts to pump seawater into the reactor core are continuing.

On 18 March, Japan assigned an INES rating of 5 to this unit.

→ Further information on ratings and INES scale.

Unit 2

Coolant within Unit 2 is covering about half of the fuel rods in the reactor, leading to fuel damage. Following an explosion on 15 March, Japanese officials expressed concerns that the reactor's containment may not be fully intact. NISA officials reported on 18 March that white smoke continues to emerge from the building.

Efforts to pump seawater into the reactor core are continuing.

On 18 March, Japan assigned an INES rating of 5 to this unit.

Unit 3

Coolant within Unit 3 is covering about half of the fuel rods in the reactor, leading to fuel damage. High pressure within the reactor's containment led operators to vent gas from the containment. Later, an explosion destroyed the outer shell of the reactor building above the containment on 14 March.

Following the explosion, Japanese officials expressed concerns that the reactor's containment may not be fully intact. NISA officials reported on 18 March that white smoke continues to emerge from the building.

Efforts to pump seawater into the reactor core are continuing.

Of additional concern at Unit 3 is the condition of the spent fuel pool in the building. There are indications that there is an inadequate cooling water level in the pool, and Japanese authorities have addressed the problem by dropping water from helicopters into the building and spraying water from trucks. On 18 March, Japanese Self Defence Forces used seven fire trucks to continue spraying efforts. There is no data on the temperature of the water in the pool.

On 18 March, Japan assigned an INES rating of 5 to this unit.

Unit 4

All fuel had been removed from the reactor core for routine maintenance before the earthquake and placed into the spent fuel pool. A portion of the building's outer shell was damaged by the explosion at Unit 3 on 14 March, and there have been two reported fires - possibly including one in the spent fuel pool on 15 March - that extinguished spontaneously, although smoke remained visible on 18 March.

Authorities remain concerned about the condition of the spent fuel pool.

On 18 March, Japan assigned an INES rating of 4 to this site.

Unit 5 and 6

Shut down before the earthquake, there are no immediate concerns about these reactors' cores or containment. Instrumentation from both spent fuel pools, however, has shown gradually increasing temperatures. Officials have configured two diesel generators at Unit 6 to power water circulation in the spent fuel pools and cores of Units 5 and 6.

Workers have opened holes in the roofs of both buildings to prevent the possible accumulation of hydrogen, which is suspected of causing explosions at other units.

Restoration of Grid

Progress has been achieved in restoring external power to the nuclear power plant, although it remains uncertain when full power will be available.

Evacuation

Japanese authorities have informed the IAEA that the evacuation of the population from the 20-kilometre zone around Fukushima Daiichi has been successfully completed. Japanese authorities have also advised people living within 30 kilometres of the plant to remain inside.

Iodine

On 16 March, Japan's Nuclear Safety Commission recommended local authorities to instruct evacuees leaving the 20-kilometre area to ingest stable (not radioactive) iodine. The pills and syrup (for children) had been prepositioned at evacuation centers. The order recommended taking a single dose, with an amount dependent on age:

Baby 12.5 mg
1 mo.-3 yrs. 25mg
3-13 yrs. 38mg
13-40 yrs. 76mg
40+ yrs. Not necessary

Radiation Measurements

Radiation levels near Fukushima Daiichi and beyond have elevated since the reactor damage began. However, dose rates in Tokyo and other areas outside the 30-kilometre zone remain far from levels which would require any protective action. In other words they are not dangerous to human health.

At the Fukushima Daiichi nuclear plant, radiation levels spiked three times since the earthquake, but have stabilized since 16 March at levels which are, although significantly higher than the normal levels, within the range that allows workers to continue onsite recovery measures.


Fukushima Daiichi Summary Table - Units 1-6
  • Legend
  • No Immediate Concern
  • Concern
  • Severe Condition
Unit 1 2 3 4 5 6
Power (MWe/th) 460/1380 784/2381 784/2381 784/2381 784/2381 1100/3293
Type of Reactor BWR-3 BWR-4 BWR-4 BWR-4 BWR-4 BWR-5
Status at the time of event In service - auto shutdown following earthquake Shut down for outage before earthquake
Core and Fuel Damaged No fuel rods No damage expected
Containment Integrity No damage reported Damage suspected No information Outage configuration No damage expected
Off-site power Recovery ongoing Not available
Diesel generators Not available Two emergency diesel generators powering Units 5 and 6
Building Severe damage Slight damage Severe damage No damage reported
Water level in reactor pressure vessel About half of fuel assembly Outage configuration Above fuel
Pressure of reactor pressure vessel Stable Unreliable data Stabilised Outage configuration No information
Containment Pressure Drywell No information Stable Stable Outage configuration No information
Water injection to reactor pressure vessel Sea water Sea water Sea water Outage configuration Not necessary
Water injection to containment vessel Not available Not necessary
Spent fuel pool temperature No information Stabilising

IAEA Briefing on Fukushima Nuclear Emergency (18 March 2011, 14:00 UTC)


Presentations:
Summary of Reactor Status
Technical Briefing of Nuclear Safety Aspects of Situation in Japan
Technical Briefing on Radiological Situation in Japan
View Video on YouTube

On 18 March 2011, Graham Andrew, Special Adviser to the IAEA Director General on Scientific and Technical Affairs, briefed both Member States and the media on the current status of nuclear safety in Japan. His opening remarks, which he delivered at 14:00 UTC at the IAEA headquarters in Vienna, are provided below:

1. Current Situation

As I reported yesterday, the situation at the Fukushima Daiichi nuclear power plants remains very serious, but there has been no significant worsening since our last briefing.

The situation at the reactors at Units 1, 2 and 3 appears to remain fairly stable.

Seawater was injected yesterday into Unit 2 and white smoke was again observed through the blown-out panels.

At Unit 3, which was the subject of helicopter water drops yesterday, water cannons have been spraying water on the spent fuel pond and seawater was injected into the reactor pressure vessel.

An important safety concern remains the spent fuel pools at Units 3 and 4. Information is lacking on water levels and temperatures at the spent fuel pools.

Efforts are being made to restore electrical power to the whole site. Another positive development is that diesel generators are providing power for cooling for both Units 5 and 6.

No problems have been reported at the common spent fuel pool. The spent fuel in the pool is fully covered by water.

The Japanese authorities today issued new ratings for the incidents on the IAEA International Nuclear and Radiological Event Scale - INES.

They assess core damage at the Fukushima Daiichi 1, 2 and 3 reactor Units, caused by the loss of all cooling function, as 5 on the INES scale.

The situation at Unit 4, where cooling and water supply in the spent fuel pool have been lost, is rated 3 by the Japanese authorities.

At the Fukushima Daini nuclear power plant, the loss of cooling functions in Units 1, 2 and 4 has also been rated as 3. All reactor Units at Fukushima Daini are now in a cold shut down condition.

2. Radiation Monitoring

As mentioned yesterday, regular dose rate information is now being received from 47 Japanese cities.

Dose rates in Tokyo and other cities remain far from levels which would require action - in other words they are not dangerous to human health.

First measurements in Tokyo by the Agency's newly arrived radiation monitoring team today showed no indication of Iodine-131 or Caesium-137. A second sampling will be carried out overnight.

3. Agency Activities

As you know, the Director General is in Tokyo, where he met the Prime Minister and other senior government ministers as well as the Vice-President of Tepco. The Director General stressed the importance of providing faster and more detailed information about the situation at the nuclear power plants, including to the international community. He also emphasized the importance of Japan working closely with the international community to resolve the crisis.

There was agreement between the Agency and our Japanese counterparts that the Agency mission would focus on radiation measurements and the identification of Japanese needs for a future environmental monitoring programme.

The Agency has started radiation measurements in Tokyo, as I mentioned, and we will move towards the Fukushima region as soon as possible. The Japanese counterparts confirmed their willingness to further strengthen their cooperation with the Agency and make available measurements made by TEPCO and the Ministry of Education, Culture, Sports, Science and Technology.

The Director General plans to brief the Agency's Board of Governors on his return from Japan.

Following our request yesterday, the CTBTO informed us today that data from its radionuclide monitoring stations will be made available to the Agency with immediate effect. On behalf of the Director General, I express my thanks to CTBTO Executive Secretary, Mr. Tibor Toth.

The International Civil Aviation Organization, in consultation with the Agency and a number of other international organizations, said today that international flight and maritime operations can continue normally into and out of Japan's major airports and sea ports and there is no medical basis for imposing additional measures to protect passengers. This will be kept under review.

Agency staff continue to work around the clock. We intend to hold another Technical Briefing and press conference at the same time tomorrow, Saturday.

Fukushima Nuclear Accident Update (18 March 2011, 12:25 UTC)


Japanese authorities have informed the IAEA that, prior to the earthquake of 11 March, the entire fuel core of reactor Unit 4 of the Fukushima Daiichi nuclear power plant had been unloaded from the reactor and placed in the spent fuel pond located in the reactor's building.

Clarification

Contrary to several news reports, the IAEA to date has NOT received any notification from the Japanese authorities of people sickened by radiation contamination.

In the report of 17 March 01:15 UTC, the cases described were of people who were reported to have had radioactive contamination detected on them when they were monitored.

Fukushima Nuclear Accident Update (18 March 2011, 10:15 UTC)


Japanese authorities have informed the IAEA that new INES ratings have been issued for some of the events relating to the nuclear emergency at the Fukushima Daiichi and Daini nuclear power plants.

Japanese authorities have assessed that the core damage at the Fukushima Daiichi 2 and 3 reactor Units caused by loss of all cooling function has been rated as 5 on the INES scale.

Japanese authorities have assessed that the loss of cooling and water supplying functions in the spent fuel pool of the Unit 4 reactor has been rated as 3.

Japanese authorities have assessed that the loss of cooling functions in the reactor Units 1, 2 and 4 of the Fukushima Daini nuclear power plant has also been rated as 3. All reactor Units at Fukushima Daini nuclear power plant are now in a cold shut down condition.

Addition of 12:45 UTC

Japanese authorities have assessed that the core damage at the Fukushima Daiichi 1 reactor unit caused by the loss of all cooling function has been rated as 5 on the INES scale.

This is an upgrade from a previous rating of 12 March as 4 on the INES scale, which was based on an abnormal rise of radioactive dose rate at the site boundary.

→ Further information on ratings and INES scale.

Fukushima Nuclear Accident Update (18 March 2011, 06:10 UTC)


Temperature of Spent Fuel Pools at Fukushima Daiichi Nuclear Power Plant - Updated

Spent fuel removed from a nuclear reactor is highly radioactive and generates intense heat. Nuclear plant operators typically store this material in pools of water that cool the fuel and shield the radioactivity. Water in a spent fuel pool is continuously cooled to remove heat produced by spent fuel assemblies. According to IAEA experts, a typical spent fuel pool temperature is kept below 25 °C under normal operating conditions. The temperature of a spent fuel pool is maintained by constant cooling, which requires a constant power source.

Given the intense heat and radiation that spent fuel assemblies can generate, spent fuel pools must be constantly checked for water level and temperature. If fuel is no longer covered by water or temperatures reach a boiling point, fuel can become exposed and create a risk of radioactive release. The concern about the spent fuel pools at Fukushima Daiichi is that sources of power to cool the pools have been compromised.

Concern about spent fuel storage conditions has led Japanese officials to drop and spray water from helicopters and trucks onto Unit 3 at Fukushima Daiichi nuclear power plant (See earlier update).

Japan's Nuclear and Industrial Safety Agency has reported increasing temperatures in the spent fuel ponds at Units 5 and 6 since 14 March. An emergency diesel generator at Unit 6 is now powering water injection into the ponds at those Units, according to NISA.

The IAEA can confirm the following new information regarding the temperatures of the spent nuclear fuel pools at Units 4, 5 and 6 at Fukushima Daiichi nuclear power plant:

Unit 4
13 March, 19:08 UTC: 84 °C
Unit 5
17 March, 03:00 UTC: 64.2 °C
17 March, 18:00 UTC: 65.5 °C
Unit 6
17 March, 03:00 UTC: 62.5 °C
17 March, 18:00 UTC: 62.0 °C

The IAEA is continuing to seek further information about the water levels, temperature and condition of all spent fuel pool facilities at the Fukushima Daiichi nuclear power plant.

Fukushima Nuclear Accident Update (17 March 2011, 16:55 UTC) - Clarified


Japanese authorities have informed the IAEA that engineers were able have begun to lay an external grid power line cable to Unit 2. The operation was completed at 08:30 UTC. The operation was continuing as of 20:30 UTC, Tokyo Electric Power Company officials told the Nuclear and Industrial Safety Agency.

They plan to reconnect power to Unit 2 once the spraying of water on the Unit 3 reactor building is completed.

The spraying of water on the Unit 3 reactor building was temporarily stopped at 11:09 UTC (20:09 local time) of 17 March.

The IAEA continues to liaise with the Japanese authorities and is monitoring the situation as it evolves.

IAEA Briefing on Fukushima Nuclear Emergency (17 March 2011, 14:00 UTC)


Presentations:
Technical Briefing on Situation in Japan
Watch Video: IAEA Teams Assist Japan in Monitoring Radiation from Fukushima

At the IAEA headquarters in Vienna, Graham Andrew, Special Adviser to the IAEA Director General on Scientific and Technical Affairs, briefed both Member States and the media on the current status of nuclear safety in Japan.

1. Current Situation

The situation at the Fukushima Daiichi nuclear power plants remains very serious, but there has been no significant worsening since yesterday.

The current situation at Units 1, 2 and 3, whose cores have suffered damage, appears to be relatively stable. Sea water is being injected into all three Units using fire extinguishing hoses. Containment pressures are fluctuating.

Military helicopters carried out four water drops over Unit 3.

Unit 4 remains a major safety concern. No information is available on the level of water in the spent fuel pool. No water temperature indication from the Unit 4 spent fuel pool has been received since 14 March, when the temperature was 84 °C. No roof is in place.

The water levels in the reactor pressure vessels of Units 5 and 6 have been declining.

2. Radiation Monitoring

We are now receiving dose rate information from 47 Japanese cities regularly. This is a positive development. In Tokyo, there has been no significant change in radiation levels since yesterday. They remain well below levels which are dangerous to human health.

As far as on-site radiation levels at the Fukushima Daiichi and Daini nuclear power plants are concerned, we have received no new information since the last report.

In some locations at around 30 km from the Fukushima plant, the dose rates rose significantly in the last 24 hours (in one location from 80 to 170 microsievert per hour and in another from 26 to 95 microsievert per hour). But this was not the case at all locations at this distance from the plants.

Dose rates to the north-west of the nuclear power plants, were observed in the range 3 to 170 microsievert per hour, with the higher levels observed around 30 km from the plant.

Dose rates in other directions are in the 1 to 5 microsievert per hour range.

3. Agency Activities

The Director General, who is now on his way to Japan, had another conversation with United Nations Secretary-General Ban Ki-Moon. The UN Secretary-General pledged all possible support for the Agency's efforts.

The Director General also met the Executive Secretary of the Comprehensive Nuclear Test Ban Treaty Organization (CTBTO), Tibor Toth, to discuss the possibility of the Agency gaining access to data collected by CTBTO radionuclide monitoring stations.

A written request has been made to CTBTO. We believe the additional data and information could assist the Agency in our assessment of the evolving situation in Japan.

A specialist from the World Meteorological Organization (WMO) joined our team in the Incident and Emergency Centre earlier this week, providing expert advice on the possible trajectories of winds from the area of the power plants.

Fukushima Nuclear Accident Update (17 March 2011, 11:05 UTC)


Based on a press release from the Japanese Chief Cabinet Secretary dated 17 March 2011, 04:00 UTC, the IAEA can confirm that the Japanese military carried out four helicopter water droppings over the building of reactor Unit 3 of the Fukushima Daiichi nuclear power plant.

According to the press release, the droppings took place between 00:48 UTC and 01:00 UTC.

Fukushima Nuclear Accident Update (17 March 2011, 01:15 UTC)


Injuries or Contamination at Fukushima Daiichi Nuclear Power Plant

Based on a press release from the Japanese Chief Cabinet Secretary dated 16 March 2011, the IAEA can confirm the following information about human injuries or contamination at the Fukushima Daiichi nuclear power plant.

Please note that this list provides a snapshot of the latest information made available to the IAEA by Japanese authorities. Given the fluid situation at the plant, this information is subject to change.

Injuries

  • 2 TEPCO employees have minor injuries;
  • 2 subcontractor employees are injured, one person suffered broken legs and one person whose condition is unknown was transported to the hospital;
  • 2 people are missing;
  • 2 people were "suddenly taken ill";
  • 2 TEPCO employees were transported to hospital during the time of donning respiratory protection in the control centre;
  • 4 people (2 TEPCO employees, 2 subcontractor employees) sustained minor injuries due to the explosion at Unit 1 on 11 March and were transported to the hospital; and
  • 11 people (4 TEPCO employees, 3 subcontractor employees and 4 Japanese civil defense workers) were injured due to the explosion at Unit 3 on 14 March.

Radiological Contamination

  • 17 people (9 TEPCO employees, 8 subcontractor employees) suffered from deposition of radioactive material to their faces, but were not taken to the hospital because of low levels of exposure;
  • One worker suffered from significant exposure during "vent work," and was transported to an offsite center;
  • 2 policemen who were exposed to radiation were decontaminated; and
  • Firemen who were exposed to radiation are under investigation.

The IAEA continues to seek information from Japanese authorities about all aspects of the Fukushima Daiichi nuclear plant.

Fukushima Nuclear Accident Update (16 March 2011, 22:00 UTC)


Temperature of Spent Fuel Pools at Fukushima Daiichi Nuclear Power Plant

Spent fuel that has been removed from a nuclear reactor generates intense heat and is typically stored in a water-filled spent fuel pool to cool it and provide protection from its radioactivity. Water in a spent fuel pool is continuously cooled to remove heat produced by spent fuel assemblies. According to IAEA experts, a typical spent fuel pool temperature is kept below 25 °C under normal operating conditions. The temperature of a spent fuel pool is maintained by constant cooling, which requires a constant power source.

Given the intense heat and radiation that spent fuel assemblies can generate, spent fuel pools must be constantly checked for water level and temperature. If fuel is no longer covered by water or temperatures reach a boiling point, fuel can become exposed and create a risk of radioactive release. The concern about the spent fuel pools at Fukushima Daiichi is that sources of power to cool the pools may have been compromised.

The IAEA can confirm the following information regarding the temperatures of the spent nuclear fuel pools at Units 4, 5 and 6 at Fukushima Daiichi nuclear power plant:

Unit 4
14 March, 10:08 UTC: 84 °C
15 March, 10:00 UTC: 84 °C
16 March, 05:00 UTC: no data
Unit 5
14 March, 10:08 UTC: 59.7 °C
15 March, 10:00 UTC: 60.4 °C
16 March, 05:00 UTC: 62.7 °C
Unit 6
14 March, 10:08 UTC: 58.0 °C
15 March, 10:00 UTC: 58.5 °C
16 March, 05:00 UTC: 60.0 °C

The IAEA is continuing to seek further information about the water levels, temperature and condition of all spent fuel pool facilities at the Fukushima Daiichi nuclear power plant.

IAEA Director General to Travel to Japan (16 March 2011, 18:50 UTC)


Watch Video

Director General Yukiya Amano announced the following today in Vienna:

"I plan to fly to Japan as soon as possible, hopefully tomorrow, to see the situation for myself and learn from our Japanese counterparts how best the IAEA can help. I will request that the Board of Governors meet upon my return to discuss the situation. My intention is that the first IAEA experts should leave for Japan as soon as possible."

On 15 March, Japan requested the IAEA for assistance in the areas of environmental monitoring and the effects of radiation on human health, asking for IAEA teams of experts to be sent to Japan to assist local experts.

Given the fast-changing situation in Japan, the Director General was unable to announce the itinerary for his trip. He expects to be in Japan for a short amount of time and then return to Vienna.

Fukushima Nuclear Accident Update (16 March 2011, 14:55 UTC)


Japanese authorities have reported concerns about the condition of the spent nuclear fuel pool at Fukushima Daiichi Unit 3 and Unit 4. Japanese Defense Minister Toshimi Kitazawa announced Wednesday that Special Defence Forces helicopters planned to drop water onto Unit 3, and officials are also preparing to spray water into Unit 4 from ground positions, and possibly later into Unit 3. Some debris on the ground from the 14 March explosion at Unit 3 may need to be removed before the spraying can begin.

Fukushima Nuclear Accident Update (16 March 2011, 03:55 UTC)


Japanese authorities have informed the IAEA that a fire in the reactor building of Unit 4 of the Fukushima Daiichi nuclear power plant was visually observed at 20:45 UTC of 15 March. As of 21:15 UTC of the same day, the fire could no longer be observed.

Fire of 14 March

As previously reported, at 23:54 UTC of 14 March a fire had occurred at Unit 4. The fire lasted around two hours and was confirmed to be extinguished at 02:00 UTC of 15 March.

Water Level in Unit 5

Japanese authorities have also informed the IAEA that at 12:00 UTC of 15 March the water level in Unit 5 had decreased to 201 cm above the top of the fuel. This was a 40 cm decrease since 07:00 UTC of 15 March. Officials at the plant were planning to use an operational diesel generator in Unit 6 to supply water to Unit 5.

The IAEA continues to liaise with the Japanese authorities and is monitoring the situation as it evolves.

Fukushima Nuclear Accident Update (15 March 2011, 22:30 UTC)


Japanese authorities have informed the IAEA that the evacuation of the population from the 20-kilometre zone around Fukushima Daiichi has been successfully completed.

The Japanese authorities have also advised that people within a 30-km radius to take cover indoors. Iodine tablets have been distributed to evacuation centres but no decision has yet been taken on their administration.

The IAEA continues to liaise with the Japanese authorities and is monitoring the situation as it evolves.

Fukushima Nuclear Accident Update (15 March 2011, 20:35 UTC)


The Japanese government today requested assistance from the IAEA in the areas of environmental monitoring and the effects of radiation on human health, asking for IAEA teams of experts to be sent to Japan to assist local experts. Preparations for these missions are currently under way.

The missions will draw on IAEA resources and may also possibly involve Response and Assistance Network (RANET) and Member States' capabilities.

This development follows the IAEA's offer to Japan of its "Good Offices" - i.e. making available the Agency's direct support and coordination of international assistance.

RANET is a network of resources made available by IAEA Member States that can be offered in the event of a radiation incident or emergency. Coordination of RANET is done by the IAEA within the framework of the Convention on Assistance in the Case of a Nuclear Accident or Radiological Emergency.

The IAEA continues to liaise with the Japanese authorities and is monitoring the situation as it evolves.

Fukushima Nuclear Accident Update (15 March 2011, 18:00 UTC)


The IAEA can confirm the following information about the status of the Fukushima Daiichi nuclear power plant:

Unit 4 was shut down for a routine, planned maintenance outage on 30 November 2010. After the outage, all fuel from the reactor was transferred to the spent fuel pool.

Units 5 and 6 were shut down at the time of the earthquake. Unit 5 was shut down as of 3 January 2011. Unit 6 was shut down as of 14 August 2010. Both reactors are currently loaded with fuel.

As of 00:16 UTC on 15 March, plant operators were considering the removal of panels from Units 5 and 6 reactor buildings to prevent a possible build-up of hydrogen in the future. It was a build-up of hydrogen at Units 1, 2 and 3 that led to explosions at the Daiichi facilities in recent days.

The IAEA continues to monitor and seek information on the status of plant workers, reactor conditions, and spent nuclear fuel at the Fukushima Daiichi nuclear plant.

Fukushima Nuclear Accident Update (15 March 2011, 15:30 UTC)


An earthquake of 6.1 magnitude was reported today at 13:31 UTC in Eastern Honshu, Japan. The Hamaoka nuclear power plant is sited an estimated 100 kilometres from the epicentre.

IEC confirmed with Japan that the plant continues to operate safely.

Units 1 and 2 are decommissioned, Unit 3 is under inspection and not operational, and Units 4 and 5 remain in safe operational status after the earthquake.

Fukushima Nuclear Accident Update (15 March 2011, 14:10 UTC)


The IAEA Incident and Emergency Centre (IEC) continues to monitor the status of the nuclear power plants in Japan that were affected by the devastating earthquake and consequent tsunami.

All Units at the Fukushima Daini, Onagawa, and Tokai nuclear power plants are in a safe and stable condition (i.e. cold shutdown).

The IAEA remains concerned over the status of the Fukushima Daiichi nuclear power plant, where sea water injections to cool the reactors in Units 1, 2 and 3 are continuing. Attempts to return power to the entire Daiichi site are also continuing.

After explosions at both Units 1 and 3, the primary containment vessels of both Units are reported to be intact. However, the explosion that occurred at 21:14 UTC on 14 March at the Fukushima Daiichi Unit 2 may have affected the integrity of its primary containment vessel. All three explosions were due to an accumulation of hydrogen gas.

A fire at Unit 4 occurred on 14 March 23:54 UTC and lasted two hours. The IAEA is seeking clarification on the nature and consequences of the fire.

The IAEA continues to seek details about the status of all workers, reactors and spent fuel at the Fukushima Daiichi plant.

An evacuation of the population from the 20-kilometre zone around Fukushima Daiichi is in effect. The Japanese have advised that people within a 30-km radius shall take shelter indoors. Iodine tablets have been distributed to evacuation centres but no decision has yet been taken on their administration.

A 30-kilometre no-fly zone has been established around the Daiichi plant. Normal civil aviation beyond this zone remains uninterrupted. The Japan Coast Guard established evacuation warnings within 10 kilometres of Fukushima Daiichi and 3 kilometres of Fukushima Daini.

The IAEA and several other UN organizations held a meeting at 11:00 UTC today to discuss recent developments and coordinate activities related to consequences of the earthquake and tsunami. The meeting was called under the framework of the Joint Radiation Emergency Management Plan of the International Organizations, and this group expects to work closely together in the days ahead.

IAEA Director General's Briefing on Day 5 of Japanese Earthquake Emergency (15 March 2011, 14:00 UTC)


Presentations:
Photo Gallery, Flickr
Watch Video

IAEA Director General Yukiya Amano briefed both Member States and the media on developments at the Fukushima Daiichi nuclear power plant.

Fukushima Nuclear Accident Update (15 March 2011, 11:25 UTC)


Fukushima Daiichi Nuclear Power Plant Update

Radiation Dose Rates Observed at Site

The Japanese authorities have informed the IAEA that the following radiation dose rates have been observed on site at the main gate of the Fukushima Daiichi Nuclear Power Plant.

At 00:00 UTC on 15 March a dose rate of 11.9 millisieverts (mSv) per hour was observed. Six hours later, at 06:00 UTC on 15 March a dose rate of 0.6 millisieverts (mSv) per hour was observed.

These observations indicate that the level of radioactivity has been decreasing at the site.

As reported earlier, a 400 millisieverts (mSv) per hour radiation dose observed at Fukushima Daiichi occurred between Units 3 and 4. This is a high dose-level value, but it is a local value at a single location and at a certain point in time. The IAEA continues to confirm the evolution and value of this dose rate. It should be noted that because of this detected value, non-indispensible staff was evacuated from the plant, in line with the Emergency Response Plan, and that the population around the plant is already evacuated.

About 150 persons from populations around the Daiichi site have received monitoring for radiation levels. The results of measurements on some of these people have been reported and measures to decontaminate 23 of them have been taken. The IAEA will continue to monitor these developments.

Evacuation of the population from the 20 kilometre zone is continuing.

The Japanese have asked that residents out to a 30 km radius to take shelter indoors. Japanese authorities have distributed iodine tablets to the evacuation centres but no decision has yet been taken on their administration.

Background on Radiation

A person's radiation exposure due to all natural sources amounts on average to about 2.4 millisievert (mSv) per year. A sievert (Sv) is a unit of effective dose of radiation. Depending on geographical location, this figure can vary by several hundred percent.

Since one sievert is a large quantity, radiation doses are typically expressed in millisievert (mSv) or microsievert (µSv), which is one-thousandth or one millionth of a sievert. For example, one chest X-ray will give about 0.2 mSv of radiation dose.

For further information on radiation, see Radiation in Everyday Life.

Fukushima Nuclear Accident Update (15 March 2011, 07:35 UTC)


Japanese authorities have confirmed that the fire at the spent fuel storage pond at the Unit 4 reactor of Fukushima Daiichi nuclear power plant was extinguished on 15 March at 02:00 UTC.

Please note that all future communications from the IAEA regarding events in Japan will use the Coordinated Universal Time (UTC) standard.

The IAEA continues to liaise with the Japanese authorities and is monitoring the situation as it evolves.

Fukushima Nuclear Accident Update (15 March 2011, 05:15 UTC)


Japanese authorities informed the IAEA that there has been an explosion at the Unit 2 reactor at the Fukushima Daiichi plant. The explosion occurred at around 06:20 on 15 March local Japan time.

Japanese authorities also today informed the IAEA at 04:50 CET that the spent fuel storage pond at the Unit 4 reactor of the Fukushima Daiichi nuclear power plant is on fire and radioactivity is being released directly into the atmosphere.

Dose rates of up to 400 millisievert per hour have been reported at the site. The Japanese authorities are saying that there is a possibility that the fire was caused by a hydrogen explosion.

The IAEA is seeking further information on these developments.

The IAEA continues to liaise with the Japanese authorities and is monitoring the situation as it evolves.

Fukushima Nuclear Accident Update (15 March 2011, 02:35 UTC)


Japanese authorities yesterday reported to the IAEA at 20:05 UTC that the reactors Units 1, 2 and 3 of the Fukushima Daini nuclear power plant are in cold shutdown status. This means that the pressure of the water coolant is at around atmospheric level and the temperature is below 100 °C. Under these conditions, the reactors are considered to be safely under control.

Japanese authorities have also informed the IAEA that teams of experts from Tokyo Electric Power Company (TEPCO), the plant's operator, are working to restore cooling in the reactor Unit 4 and bring it to cold shutdown.

The IAEA continues to liaise with the Japanese authorities and is monitoring the situation as it evolves.

Fukushima Nuclear Accident Update (14 March 2011, 22:03 UTC)


After the IAEA offered its "Good Offices" to Japan - i.e. making available the Agency's direct support and coordination of international assistance - the Japanese government yesterday asked the IAEA to provide expert missions to the country. Discussions have begun to prepare the details of those missions.

At a briefing for representatives of IAEA Member States held yesterday in Vienna, IAEA Director General Yukiya Amano outlined some of the areas in which IAEA support could be provided to Japan.

"The IAEA can offer support in technical areas such as radiation surveys and environmental sampling, medical support, the recovery of missing or misplaced radioactive sources or advice on emergency response," he said.

In addition, the IAEA is coordinating assistance from Member States through the Response and Assistance Network (RANET). The network consists of nations that can offer specialized assistance after a radiation incident or emergency. Coordination by the IAEA takes place within the framework of the Convention on Assistance in the Case of a Nuclear Accident or Radiological Emergency.

The IAEA continues to liaise with the Japanese authorities and is monitoring the situation as it evolves.

IAEA Director General Briefs Media on Nuclear Safety in Japan (14 March 2011, 16:45 UTC)


Presentations:
Director General Statement
Photo Gallery, Flickr
Watch Video

At 16:45 UTC on 14 March 2011, IAEA Director General Yukiya Amano briefed the media on the consequences of the twin natural disasters in Japan.

The press conference was opened by IAEA Director General Yukiya Amano, followed by comments from James Lyons, Director of the Division of Nuclear Installation Safety; Denis Flory, Deputy Director General for the Department of Nuclear Safety and Security; and Alena Buglova, acting Head of the Incident and Emergency Centre.

Fukushima Nuclear Accident Update (14 March 2011, 14:35 UTC)


Fukushima Daiichi Nuclear Power Plant

Japanese authorities have reported to the IAEA that Fukushima Daiichi Unit 2 has experienced decreasing coolant levels in the reactor core. Officials have begun to inject sea water into the reactor to maintain cooling of the reactor core.

Sea water injections into Units 1 and 3 were interrupted yesterday due to a low level in a sea water supply reservoir, but sea water injections have now been restored at both Units.

Evacuation Status

On 12 March, the Japanese Prime Minister ordered the evacuation of residents living within 10 kilometres of the Fukushima Daini nuclear power plant and within 20 kilometres of the Fukushima Daiichi nuclear power plant.

Japan's Nuclear and Industrial Safety Agency (NISA) has reported that about 185 000 residents had been evacuated from the towns listed below as of 13 March 2011, 17:00 (JST).

Populations of Evacuated Towns Near Affected Nuclear Power Plants

Hirono-cho 5 387
Naraha-cho 7 851
Tomioka-cho 15 786
Okuma-cho 11 186
Futaba-cho 6 936
Namie-cho 20 695
Tamura-shi 41 428
Minamisouma-shi 70 975
Kawauchi-mura 2 944
Kuzuo-mura 1 482
Total 184 670

Iodine Distribution

Japan has distributed 230 000 units of stable iodine to evacuation centres from the area around Fukushima Daiichi and Fukushima Daini nuclear power plants, according to officials. The iodine has not yet been administered to residents; the distribution is a precautionary measure in the event that this is determined to be necessary.

The ingestion of stable iodine can help to prevent the accumulation of radioactive iodine in the thyroid.

Weather Forecast

In partnership with the World Meteorological Organization (WMO), the IAEA is continuing to monitor weather forecasts and is providing updates to Member States. Since the incident began, winds have been moving away from the Japanese coast to the East, and predictions call for the same patterns to persist for the next three days.

The IAEA continues to liaise with the Japanese authorities and is monitoring the situation as it evolves.

IAEA Director General Briefed on Disaster Response and Nuclear Safety (14 March 2011, 08:30 UTC)


Watch Video

At the IAEA's Incident and Emergency Centre (IEC) and at its International Seismological Safety Centre (ISSC), IAEA Director General Yukiya Amano received a briefing at 08:30 UTC.

The IAEA emergency management experts detailed the status of emergency communications with Japanese authorities, as well as with emergency management counterparts in other IAEA Member States and among international organizations.

Director General Amano was briefed as well on nuclear safety, seismological activity, and the on-going disaster recovery efforts in Japan. The video of the briefing is available here.

Fukushima Nuclear Accident Update (14 March 2011, 06:00 UTC)


Japan's Nuclear and Industrial Safety Agency (NISA) has provided the IAEA with further information about the hydrogen explosion that occurred today at the Unit 3 reactor at the Fukushima Daiichi nuclear plant. A hydrogen explosion occurred at Unit 3 on 14 March at 11:01 am local Japan time.

All personnel at the site are accounted for. Six people have been injured.

The reactor building exploded but the primary containment vessel was not damaged. The control room of Unit 3 remains operational.

The IAEA continues to liaise with the Japanese authorities and is monitoring the situation as it evolves.

Fukushima Nuclear Accident Update (14 March 2011, 04:15 UTC)


Based on information provided by Japanese authorities, the IAEA can confirm the following information about the status of Units 1, 2, 3 and 4 at Fukushima Daini nuclear power plant.

All four Units automatically shut down on 11 March. All Units have off-site power and water levels in all Units are stable. Though preparations have been made to do so, there has been no venting to control pressure at any of the plant's Units.

At Unit 1, plant operators were able to restore a residual heat remover system, which is now being used to cool the reactor. Work is in progress to achieve a cold shutdown of the reactor.

Workers at Units 2 and 4 are working to restore residual heat removal systems.

Unit 3 is in a safe, cold shutdown.

Radiation dose rate measurements observed at four locations around the plant's perimeter over a 16-hour period on 13 March were all normal.

Fukushima Nuclear Accident Update (14 March, 2011, 03:00 UTC)


Japan's Nuclear and Industrial Safety Agency (NISA) has informed the IAEA that there has been an explosion at the Unit 3 reactor at the Fukushima Daiichi nuclear plant.

The explosion occurred at 11:01 am local Japan time.

The IAEA is seeking further information on this development.

Fukushima Nuclear Accident Update (14 March 2011, 00:30 UTC) - Clarified


Based on information provided by Japanese authorities, the IAEA can confirm the following information about the status of Units 1, 2 and 3 at Fukushima Daiichi nuclear power plant.

Unit 1 is being powered by mobile power generators on site, and work continues to restore power to the plant. There is currently no power via off-site power supply or backup diesel generators being provided to the plant. Seawater and boron are being injected into the reactor vessel to cool the reactor. Due to the explosion on 12 March, the outer shell of the containment building has been lost.

Unit 2 is being powered by mobile power generators on site, and work continues to restore power to the plant. There is currently neither off-site power supply nor backup diesel generators providing power to the plant. The reactor core is being cooled through reactor core isolation cooling, a procedure used to remove heat from the core. The current reactor water level is lower than normal but remains steady. The outer shell of the containment building is intact at Unit 2.

Unit 3 does not have off-site power supply nor backup diesel generators providing power to the plant. As the high pressure injection system and other attempts to cool the reactor core have failed, injection of water and boron into the reactor vessel has commenced. Water levels inside the reactor vessel increased steadily for a certain amount of time but readings indicating the water level inside the pressure vessel are no longer showing an increase. The reason behind this is unknown at this point in time. To relieve pressure, venting of the containment started on 13 March at 9:20 am local Japan time. Planning is underway to reduce the concentration of hydrogen inside the containment building. The containment building is intact at Unit 3.

The IAEA is seeking information about the status of spent fuel at the Daiichi plant.

Fukushima Nuclear Accident Update (13 March 2011, 20:45 UTC)


The Japanese authorities have informed the IAEA that radioactivity levels at the site boundary of the Onagawa nuclear power plant have returned down to normal background levels. The first (ie lowest) state of emergency was reported at the plant earlier on Sunday after an increased level of radioactivity was detected at the site boundary. Investigations at the site indicate that no emissions of radioactivity have occurred from any of the three Units at Onagawa. The current assumption of the Japanese authorities is that the increased level may have been due to a release of radioactive material from the Fukushima Daiichi nuclear power plant.

The IAEA continues to liaise with the Japanese authorities and is monitoring the situation as it evolves.

Fukushima Nuclear Accident Update (13 March 2011, 12:35 UTC)


Japanese authorities have informed the IAEA's Incident and Emergency Centre (IEC) that venting of the containment of reactor Unit 3 of the Fukushima Daiichi nuclear power plant started at 9:20 am local Japan time of 13 March through a controlled release of vapour. The operation is intended to lower pressure inside the reactor containment.

Subsequently, following the failure of the high pressure injection system and other attempts of cooling the plant, injection of water first and sea water afterwards started. The authorities have informed the IAEA that accumulation of hydrogen is possible.

Japanese authorities have also informed the IAEA that the first (i.e. lowest) state of emergency at the Onagawa nuclear power plant has been reported by Tohoku Electric Power Company. The authorities have informed the IAEA that the three reactor Units at the Onagawa nuclear power plant are under control.

As defined in Article 10 of Japan's Act on Special Measures Concerning Nuclear Emergency Preparedness, the alert was declared as a consequence of radioactivity readings exceeding allowed levels in the area surrounding the plant. Japanese authorities are investigating the source of radiation. The IAEA has offered its "Good Offices" to Japan to support the nation's response to the 11 March earthquake and tsunami. One IAEA capability intended to help member states during crises is the Response and Assistance Network (RANET). The network consists of nations that can offer specialized assistance after a radiation incident or emergency. Such assistance is coordinated by the IAEA within the framework of the Assistance Convention.

The IAEA continues to liaise with the Japanese authorities and is monitoring the situation as it evolves.

Fukushima Nuclear Accident Update (13 March 2011, 02:35 CET) - Corrected


An earlier version of this release incorrectly described pressure venting actions at Units 1, 2 and 4 at the Fukushima Daini nuclear power plant. Venting did not occur at these Units.

Japanese authorities have informed the IAEA that Units 1, 2 and 4 at the Fukushima Daini retain off-site power. Daini Unit 3 is in a safe, cold shutdown, according to Japanese officials.

Japanese authorities have reported some casualties to nuclear plant workers. At Fukushima Daiichi, four workers were injured by the explosion at the Unit 1 reactor, and there are three other reported injuries in other incidents. In addition, one worker was exposed to higher-than-normal radiation levels that fall below the IAEA guidance for emergency situations. At Fukushima Daini, one worker has died in a crane operation accident and four others have been injured.

In partnership with the World Meteorological Organization, the IAEA is providing its Member States with weather forecasts for the affected areas in Japan. The latest predictions have indicated winds moving to the Northeast, away from Japanese coast over the next three days.

The IAEA continues to liaise with the Japanese authorities and is monitoring the situation as it evolves.

Fukushima Nuclear Accident Update (12 March 2011, 20:10 UTC)


Japanese authorities have informed the IAEA that the explosion at Unit 1 reactor at the Fukushima Daiichi plant occurred outside the primary containment vessel (PCV), not inside. The plant operator, Tokyo Electric Power Company (TEPCO), has confirmed that the integrity of the primary containment vessel remains intact.

As a countermeasure to limit damage to the reactor core, TEPCO proposed that sea water mixed with boron be injected into the primary containment vessel. This measure was approved by Japan's Nuclear and Industrial Safety Agency (NISA) and the injection procedure began at 20:20 local Japan time.

Japan has reported that four workers at Fukushima Daiichi were injured by the explosion.

NISA have confirmed the presence of caesium-137 and iodine-131 in the vicinity of Fukushima Daiichi Unit 1. NISA reported an initial increase in levels of radioactivity around the plant earlier today, but these levels have been observed to lessen in recent hours.

Containment remains intact at Fukushima Daiichi Units 1, 2 and 3.

Evacuations around both affected nuclear plants have begun. In the 20-kilometre radius around Fukushima Daiichi an estimated 170 000 people have been evacuated. In the 10-kilometre radius around Fukushima Daini an estimated 30 000 people have been evacuated. Full evacuation measures have not been completed.

The Japanese authorities have classified the event at Fukushima Daiichi Unit 1 as a level 4 "Accident with Local Consequences" on the International Nuclear and Radiological Event Scale (INES). The INES scale is used to promptly and consistently communicate to the public the safety significance of events associated with sources of radiation. The scale runs from 0 (deviation) to 7 (major accident).

Japan has also confirmed the safety of all its nuclear research reactors.

The IAEA continues to liaise with the Japanese authorities and is monitoring the situation as it evolves.

IAEA Director General's Update on Tsunami and Earthquake Emergency Response (12 March 2011, 19:00 UTC)


Watch Video

IAEA Director General Yukiya Amano provided a video statement on the aftermath of the earthquake and tsunami that struck Japan. Director General Amano expressed his sincerest condolences for the lives and homes lost, and said: "My heart goes out to the people of my home country as they rise to the challenge of this immense tragedy."

Director General Amano notes the current effort to prevent further damage to Unit 1 reactor at the Fukushima Daiichi nuclear power plant.

In response to the situation, Director General Amano also explained the IAEA's dual role to use emergency communication channels to exchange verified, official information between Japan and other IAEA Member States, as well as to coordinate the delivery of international assistance, should Japan or other affected countries request it.

Fukushima Nuclear Accident Update (12 March 2011, 12:40 UTC)


Japan's Nuclear and Industrial Safety Agency (NISA) has informed the IAEA's Incident and Emergency Centre (IEC) that there has been an explosion at the Unit 1 reactor at the Fukushima Daiichi plant, and that they are assessing the condition of the reactor core.

The explosion was reported to NISA by the plant operator, Tokyo Electric Power Company (TEPCO), at 0730 CET. Further details were not immediately available.

Japanese authorities have extended the evacuation zone around the Fukushima Daiichi plant to a 20-kilometre radius from the previous 10 kilometres.

At the nearby Fukushima Daini nuclear power plant, the evacuation zone has been extended to a 10-kilometre radius from the previous three kilometres.

The authorities also say they are making preparations to distribute iodine to residents in the area of both the plants.

The IAEA has reiterated its offer of technical assistance to Japan, should the government request this. The IAEA continues to liaise with the Japanese authorities, and is in full response mode to monitor the situation closely around the clock as it evolves.

Fukushima Nuclear Accident Update (12 March 2011, 06:30 UTC)


Japanese authorities have informed the IAEA's Incident and Emergency Centre (IEC) that, starting at 12 March 9:00 am local Japan time, they have started the preparation for the venting of the containment of the Unit 1 reactor at the Fukushima Daiichi plant through a controlled release of vapour. The operation is intended to lower pressure inside the reactor containment.

Evacuation of residents living within ten kilometres of the Fukushima Daiichi nuclear power plant is reported to be under way. An area with a radius of three kilometres around the plant had already been evacuated.

The evacuation of residents living within three kilometres of the Fukushima Daini nuclear power plant is also under way.

The IAEA's IEC continues to liaise with the Japanese authorities, and is in full response mode to monitor the situation closely around the clock as it evolves.

Fukushima Nuclear Accident Update (11 March 2011, 21:10 UTC)


Japanese authorities have informed the IAEA's Incident and Emergency Centre (IEC) that officials are working to restore power to the cooling systems of the Unit 2 reactor at the Fukushima Daiichi nuclear power plant. Mobile electricity supplies have arrived at the site.

Japanese officials have also reported that pressure is increasing inside the Unit 1 reactor's containment, and the officials have decided to vent the containment to lower the pressure. The controlled release will be filtered to retain radiation within the containment.

Three reactors at the plant were operating at the time of the earthquake, and the water level in each of the reactor vessels remains above the fuel elements, according to Japanese authorities.

The IAEA's IEC continues to liaise with the Japanese authorities, and is in full response mode to monitor the situation closely round the clock.

IAEA Director General Expresses Condolences Following Japan Earthquake (11 March 2011, 20:50 CET)


"I would like to express my condolences and sympathies to the people of Japan who have suffered from this earthquake and to the Government of Japan," said IAEA Director General Yukiya Amano.

Fukushima Nuclear Accident Update (11 March 2011, 20:30 CET)


Japanese authorities have informed the IAEA's Incident and Emergency Centre (IEC) that today's earthquake and tsunami have cut the supply of off-site power to the Fukushima Daiichi nuclear power plant. In addition, diesel generators intended to provide back-up electricity to the plant's cooling system were disabled by tsunami flooding, and efforts to restore the diesel generators are continuing.

At Fukushima Daiichi, officials have declared a nuclear emergency situation, and at the nearby Fukushima Daini nuclear power plant, officials have declared a heightened alert condition.

Japanese authorities say there has so far been no release of radiation from any of the nuclear power plants affected by today's earthquake and aftershocks.

The IAEA's IEC continues to liaise with the Japanese authorities, and is in full response mode to monitor the situation closely round the clock.

Fukushima Nuclear Accident Update (11 March 2011, 16:55 UTC)


Japanese authorities have informed the IAEA's Incident and Emergency Centre (IEC) that they have ordered the evacuation of residents within a three-kilometre radius of the Fukushima Daiichi nuclear power plant, and told people within a 10-kilometre radius to remain indoors.

The Japanese authorities say there has so far been no release of radiation from any of the nuclear power plants affected by today's earthquake and aftershocks.

"The IAEA continues to stand ready to provide technical assistance of any kind, should Japan request this," IAEA Director General Yukiya Amano said.

The IAEA's IEC continues to liaise with the Japanese authorities, and is in full response mode to monitor the situation closely round the clock.

Fukushima Nuclear Accident Update (11 March 2011, 11:45 UTC)


The IAEA's Incident and Emergency Centre has received information from Japan's Nuclear and Industrial Safety Agency (NISA) that a heightened state of alert has been declared at Fukushima Daiichi nuclear power plant. NISA says the plant has been shut down and no release of radiation has been detected.

Japanese authorities have also reported a fire at the Onagawa nuclear power plant, which has been extinguished. They say Onagawa, Fukushima-Daini and Tokai nuclear power plants were also shut down automatically, and no radiation release has been detected.

The IAEA received information from its International Seismic Safety Centre that a second earthquake of magnitude 6.5 has struck Japan near the coast of Honshu, near the Tokai plant.

The IAEA is seeking further details on the situation at Fukushima Daiichi and other nuclear power plants and research reactors, including information on off-site and on-site electrical power supplies, cooling systems and the condition of the reactor buildings. Nuclear fuel requires continued cooling even after a plant is shut down.

The IAEA is also seeking information on the status of radioactive sources in the country, such as medical and industrial equipment.

The World Meteorological Organization has informed the IAEA that prevailing winds are blowing eastwards, away from the Japanese coast.

All IAEA staff in Japan, both in the Tokyo office and in nuclear facilities, are confirmed to be safe.

Fukushima Nuclear Accident Update (11 March 2011, 08:30 UTC)


The IAEA's Incident and Emergency Centre received information from the International Seismic Safety Centre (ISSC) at around 08:15 CET this morning about the earthquake of magnitude 8.9 near the east coast of Honshu, Japan.

The Agency is liaising with the Japanese Ministry of Economy, Trade and Industry (METI) to confirm further details of the situation. Japanese authorities reported that the four nuclear power plants closest to the quake have been safely shut down.

The Agency has sent an offer of Good Offices to Japan, should the country request support.

Current media reports say a tsunami alert has been issued for 50 countries, reaching as far as Central America. The Agency is seeking further information on which countries and nuclear facilities may be affected.