Fukushima Nuclear Accident Update Log
Updates of 1 April 2011
- Story Resources
- In Focus: Fukushima Nuclear Accident
- Fukushima Nuclear Accident: Information Sheet
- Criteria for Use in Preparedness and Response for a Nuclear or Radiological Emergency
- International Nuclear and Radiological Event Scale (INES)
- IAEA Incident and Emergency Centre (IEC)
- International Seismic Safety Centre (ISSC)
- Response Assistance Network (RANET)
- Japan Nuclear and Industrial Safety Agency (NISA)
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.