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Fukushima Nuclear Accident in Focus

IAEA Fukushima Daiichi Status Report


15 December 2011

What are the recent developments at the Fukushima Daiichi Nuclear Power Plant?

On 8 December TEPCO released a schematic depicting the Unit 1 gas control system framework for operating in both the containment and reactor pressure vessel. TEPCO has begun setting up a process to extract gas from the Unit 1 gas system for analysis (similar to the process used to extract gas at Unit 2).

On 8 December TEPCO conducted a full night-time training exercise with 61 participants to practice restoring cooling to the reactor units under low light conditions. This training included connecting water injection hoses, connecting power cables and the deployment of backup power sources. Previous night-time training was conducted on 13 May (140 participants) and 13 October (79 participants).

On 9 December TEPCO announced the establishment of additional sea water monitoring locations to monitor if there has been any increase in seawater contamination due to the leak from the evaporative concentration apparatus.

On 12 December TEPCO released results of a detailed analysis of the radionuclide concentration at several different locations in the water treatment process.

On 12 December TEPCO released an image showing a newly discovered leak at the sampling line of the evaporative concentration facility.

On 12 December NISA released a response to the water leak report provided by TEPCO on 8 December. NISA reviewed the report and provided a list of instructions to TEPCO.

On 12 December TEPCO released results from a radionuclide analysis of the water in the basements of reactor buildings 1 through 3.

On 14 December TEPCO released results from a radionuclide analysis of the water in the basements of the turbine buildings for Unit 3 and 4.

On 14 December TEPCO released details of a survey they performed on some of the onsite solid waste storage locations. The purpose of this survey was to visually inspect the conditions of the containers in each location, to conduct a radiological survey around the containers and the storage buildings and to measure the radiological material concentration in the air inside each structure.

Table 1: Status of Cooling Water Flow, Temperatures and Pressure at Units 1, 2 and 3

TEPCO's Fukushima Daiichi Nuclear Power Plant station reactors 1, 2 and 3 require circulating water to remove heat from their fuel.

Plant operators are working to bring the reactors into a "cold shutdown condition" defined by TEPCO and the Nuclear Emergency Response Headquarters as:

  • Lowering the coolant water temperature to below 100 degrees centigrade while reducing the pressure inside the reactor vessels to the same as the outside air pressure, or 1 atmosphere (atm); and
  • Bringing release of radioactive materials from primary containment vessel under control and reducing public radiation exposure by additional release (not to exceed 1 mSv/year at the site boundary as a target).

Indications Measurement Reactor
Unit 1 Unit 2 Unit 3
Water Flow Into Reactor1 Litres/hour 4 400 8 600 8 700
Reactor Vessel Pressure Atm 1.02 1.06 Downscale2
Outer Containment Vessel Pressure3 Atm 1.10 1.10 1.02
Reactor Vessel Temperature (Feed Water Nozzle)4 °C 36.9 65.2 57.4
Reactor Vessel Temperature (At Bottom of Reactor)5 °C 37.6 69.5 64.2
Suppression Pool Pressure6 Atm 0.84 Below Scale7 1.86
Date/Time of Data Acquisition   14 December
03:00 UTC
14 December
03:00 UTC
14 December
03:00 UTC
Notes:

1 Plant operators are pumping water into Unit 1 through one injection point and through two injections points in Units 2 and 3.
2 "Downscale" means the reading is below the lowest indication the instrument is capable of detecting. This is typically an indication that an instrument has failed.
3 The containment vessel completely surrounds the reactor vessel and support systems. It is designed to prevent the release of radioactive materials following an accident. Japanese plant operators are working to reduce the pressure in the containment vessel to 1 atmosphere, the same as the outside air pressure.
4 The temperature of the coolant water as it is pumped into the reactor vessels.
5 The temperature of the coolant water, measured at the bottom of the reactor vessel.
6 The suppression pool is designed to limit pressure in the containment vessel during an accident by condensing steam from the containment vessel. Japanese workers are aiming to get this pressure down to 1 atmosphere.
7 "Below scale" means the reading is below the lowest indication the instrument is capable of detecting. This is typically an indication that an instrument has failed.

Table 2: Most Recently Reported Temperatures in Fukushima Daiichi Spent Fuel Pools

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.


Location
Water Temperature
Temperature °C Date Measured
Unit 1 14.5 14 December
Unit 2 19.3 14 December
Unit 3 14.7 14 December
Unit 4 22.0 14 December
Unit 5 18.2 14 December
Unit 6 18.0 14 December
Common Spent Fuel Pool 19.0 14 December

What is the latest information regarding radiation monitoring of foodstuffs?

Food monitoring data were reported from 7 – 13 December by the Ministry of Health, Labour and Welfare (MHLW) for a total of 5389 samples collected on 6 and 20 September, 4, 20, 24-25, 27-28 and 31 October, 1-2, 4-5, 7-11, 14-19 and 21-30 November, and 1-13 December 2011 in 39 different prefectures (Aichi, Akita, Aomori, Chiba, Fukui, Fukuoka, Fukushima, Gunma, Hokkaido, Hyogo, Ibaraki, Ishikawa, Iwate, Kagawa, Kagoshima, Kanagawa, Kochi, Kumamoto, Kyoto, Mie, Miyagi, Miyazaki, Nagano, Nagasaki, Nara, Niigata, Okayama, Okinawa, Saga, Saitama, Shiga, Shimane, Shizuoka, Tochigi, Tokushima, Tokyo, Tottori, Toyama and Yamagata). Samples comprised baby and infant foods, cereals and cereal products, dairy products, eggs, flowers, vegetables, fruit and fruit products, mushrooms, nuts, tea, meat, fish and seafood.

Analytical results for 5372 (over 99.5%) of the 5389 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, 17 samples were found to be above the regulation values for radioactive caesium (Cs-134 and Cs-137), as follows:

  • As reported 7 December, two samples of common skete and one sample of brown hakeling collected on 5 December from Fukushima prefecture;
  • As reported on 8 December, two samples of kiwi fruit collected on 7 December from Fukushima prefecture; and
  • As reported on 12 December, 10 samples of boar meat collected on 17, 23, 24, 25, 28 and 30 November and on 2 and 4 December, one sample of Asian black bear meat collected on 5 December and one sample of tochu tea collected on 9 December from Fukushima prefecture.

Updated information on food restrictions was reported by MHLW on 9 December indicating that restrictions were placed on the distribution of kiwi fruit and rice (produced in 2011) from specific parts of Fukushima prefecture.

Resources Available

TEPCO has posted a page on its Website listing all of the video material it has posted between March and 30 September. These videos will remain available online until the end of December after which time they may be removed.