Brief overview of contaminated water leakage at the TEPCO’s Fukushima Daiichi Nuclear Power Station and countermeasures
August 28, 2013
Ministry of Foreign Affairs informs the brief overview of contaminated water leakage at the Tokyo Electric Power Company (TEPCO)’s Fukushima Daiichi Nuclear Power Station and countermeasures which have already been taken and will be taken.
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- The Government of Japan recognizes that taking countermeasures against the contaminated water leakages is the most urgent issue which has to be tackled. Prime Minister Abe has instructed that the government should play a responsible role in taking countermeasures against the contaminated water leakages. Against this background, the Nuclear Regulation Authority and Mr. Motegi, Minister of Economy, Trade and Industry visited the site of the Fukushima Daiichi Nuclear Power Station on 23rd and 26th August respectively.
- For the settlement of the contaminated water leakage issue as a whole, the entire government is determined to take drastic measures to the maximum extent possible together with the responses to the leakages from contaminated water tanks through such measures as investigation to the causes and recurrence prevention.
- At present, statistically-significant increase of radioactive concentration in the sea outside the port of the TEPCO’s Fukushima Daiichi Nuclear Power Station has not been detected. However, the Government of Japan will continue to pay the closest attention to the situation, make every effort to work on the contaminated water leakage issue, and provide information to the international community in an appropriate way.
Note1: Instruction by the Prime Minister at the Nuclear Emergency Response Headquarters on 8th August
“Stability of the Fukushima Daiichi Nuclear Power Station is also a challenge. Especially the issue of contaminated water is a matter of high interest of Japanese people and a matter of urgency to be tackled. The government will play a responsible role in taking countermeasures without leaving to TEPCO. I expect that the Minister of Economy, Trade and Industry will fully instruct TEPCO and take multilayered measures swiftly and firmly with a sense of speed. I expect the Chairman of the Nuclear Regulation Authority to make full efforts on the investigation of causes and taking effective measures for securing safety from the viewpoint of a regulatory authority.”
(Water leakage at a contaminated water tank in the H4 area)
- On 19th August, the puddle of water with high radiation dose was found around a contaminated water tank in the H4 area which is located about 500 m away from the sea. It is estimated that the amount of leakage contaminated water with high radiation dose is approximately 300 m3.
- On this leakage, instruction has been given as follows; (i)investigation to the causes, (ii)overall inspection of the tanks of the same type as the one causing water leakage, (iii)recurrence prevention measures, (iv)strengthening of monitoring and supervision, (v)investigation into the flows of contaminated water into the sea.
- In addition, when Mr. Motegi, Minister of Economy, Trade and Industry visited the site on 26th August, he gave the following instruction; (i)strengthening of the management of tanks and the surrounding area, (ii)strengthening of patrol, (iii)increasing of welding type tanks and the acceleration of the replacement of volt tightening type of tanks, (iv)acceleration of the treatment of water containing high amount of radio-active materials and decreasing of radiation dose of the surrounding area by collecting the contaminated soil, (v)identification of the risks of storing water containing high amount of radio-active materials and taking actions to cope with the risks.
（Estimation of the flows of contaminated water into the sea through ground water and countermeasures）
- It is estimated that approximately 1000 m3 of ground water per day flows into the TEPCO's Fukushima Daiichi Nuclear Power Station from the mountain side. About 400 m3 out of this ground water flows into the buildings. Some part of the remaining 600 m3 water runs through the contamination source inside the trench, which flowed in at the beginning of the accident, and then flows into the sea as contaminated water.
- Immediate countermeasures such as the improvement of the contaminated soil by sodium silicate (liquid glass) have been taken. At the same time, the Committee on Countermeasures for Contaminated Water Treatment will consider drastic countermeasures such as the installation of land-side impermeable walls adopting the frozen soil method and make a summary around mid-September.
Note2: The Committee on Countermeasures for Contaminated Water Treatment will consider immediate and drastic countermeasures for the solution of the issue of contaminated water through ground water and make a summary around mid-September.
- Removing water containing high amount of radio-active materials from the trench.
- Improving the contaminated soil by sodium silicate (liquid glass).
- Decreasing the inflows of water by pumping out ground water from the mountain-side (by-passing ground water).
Drastic countermeasures (Coming 1-2 years)
- Pumping out the ground water from the sub-drains.
- Installation of impermeable walls in the sea.
- Installation of land-side impermeable walls in order to prevent the inflow of water from the mountain and then to the sea.
Note3: Information sharing with the international community
Since the occurrence of the accident at the TEPCO’s Fukushima Daiichi Nuclear Power Station, the Government of Japan has been actively providing information on the situation of the accident. On the contaminated water leakage this time, the Ministry of Foreign Affairs provided information to all missions in Japan and IAEA etc. on 22nd July, 2nd August, 8th August, 21st August (2 times) and 28th August.