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En 2014, des centaines de réservoirs de stockage contenaient 400 000 m 3 d'eau utilisée pour refroidir les réacteurs après la crise de la centrale nucléaire de Fukushima Daiichi, un volume qui continue d'augmenter.
See later section on A significant problem in tracking radioactive release was that 23 out of the 24 radiation monitoring stations on the plant site were disabled by the tsunami.There is some uncertainty about the amount and exact sources of radioactive releases to air. Daiichi units 2, 3 and 5 exceeded their maximum response acceleration design basis in E-W direction by about 20%. Regarding releases to air and also water leakage from Fukushima Daiichi, the main radionuclide from among the many kinds of fission products in the fuel was volatile iodine-131, which has a half-life of 8 days. Without heat removal by circulation to an outside heat exchanger, this produced a lot of steam in the reactor pressure vessels housing the cores, and this was released into the dry primary containment (PCV) through safety valves. Here the fuel would have been uncovered in about 7 days due to water boiling off. The area subject to high dose rates (over 166 mSv/yr) diminished from 27% of the 1117 kmIn August 2011 The Act on Special Measures Concerning the Handling of Radioactive Pollution was enacted and it took full effect from January 2012 as the main legal instrument to deal with all remediation activities in the affected areas, as well as the management of materials removed as a result of those activities. Gas control systems which extract and clean the gas from the PCV to avoid leakage of caesium have been commissioned for all three units.Throughout 2011 injection into the RPVs of water circulated through the new water treatment plant achieved relatively effective cooling, and temperatures at the bottom of the RPVs were stable in the range 60-76°C at the end of October, and 27-54°C in mid-January 2012. "Units 1-4 were shut down automatically due to the earthquake. About JPY 43 billion ($431 million) was due to a higher estimate of compensation coming from damages to the agriculture, forestry and fisheries industries, as well as the food processing and distribution industries. They were restored to cold shutdown by the normal recirculating system on 20th, and mains power was restored on 21-22nd.In September 2013 Tepco commenced work to remove the fuel from unit 6.
In early June NISA increased its estimate of releases to 770 PBq, from about half that, though in August the NSC lowered this estimate to 570 PBqFor Fukushima Daini, NISA declared INES Level 3 for units 1, 2, 4 – each a serious incident.Beyond whatever insurance Tepco might carry for its reactors is the question of third party liability for the accident. Il s'agirait donc d'une Pour suivre l'évolution de la situation au Japon, il est possible d'aller sur le site de l'Institut de radioprotection et de sûreté nucléaire (
Damage to the diesel generators was limited and also the earthquake left one of the external power lines intact, avoiding a station blackout as at Daiichi 1-4. As noted above, removal of the very degraded fuel will be a long process in units 1-3, but will draw on experience at Three Mile Island in the USA. It also summarised radioactive releases and their effects.Meanwhile a July 2011 report from MIT's Centre for Advanced Nuclear Energy Systems provided a useful series of observations, questions raised, and suggestions.
The Fukushima Daiichi Nuclear Power Plantcomprised six separate boiling water reactorsoriginally designed by General Electric(GE) and maintained by the Tokyo Electric Power Company(TEPCO). This would generally involve removing the fuel and then sealing them for a further decade or two while the activation products in the steel of the reactor pressure vessels decay. These submerged and damaged the seawater pumps for both the main condenser circuits and the auxiliary cooling circuits, notably the Residual Heat Removal (RHR) cooling system.
It was established within the Ministry of Education, Culture, Sports, Science and Technology (MEXT), and was led by Law Professor Yoshihisa Nomi of Gakushuin, University in Tokyo.On 11 May 2011, Tepco accepted terms established by the Japanese government for state support to compensate those affected by the accident at the Fukushima Daiichi plant. In areas where radiation levels are over 20 mSv/yr evacuees will be asked to continue living elsewhere for “a few years” until the government completes decontamination and recovery work. This compares with levels of about 2.4 mSv they would have received from unavoidable natural sources. In the event, tsunami heights coming ashore were about 15 metres, and the Daiichi turbine halls were under some 5 metres of seawater until levels subsided. They were in 'cold shutdown' at the time, but still requiring pumped cooling. These were in two stages, and are described in the The government then created a separate Nuclear Regulatory Agency (NRA) under the authority of the Environment Ministry and combining the roles of NISA and NSC, commissioned in September 2012.
NISA was also criticised for its "negligence and failure over the years" to prepare for a nuclear accident in terms of public information and evacuation, with previous governments equally culpable. TEPCO décide de le négliger, arguant que Un comité d'experts est alors chargé de revoir les normes anti-sismiques. As noted above, units 5&6 were decommissioned in 2014 and will be used for training.Earlier, consortia led by both Hitachi-GE and Toshiba submitted proposals to Tepco for decommissioning units 1-4. See section above. This was both from the tsunami inundation and leakage from reactors. Statistics indicate that an average family of four has received about JPY 90 million ($900,000) in compensation from Tepco. Overall, people in Fukushima are expected on average to receive less than 10 mSv due to the accident over their whole lifetime, compared with the 170 mSv lifetime dose from natural background radiation that people in Japan typically receive.
Le 11 mars 2011, un séisme de magnitude 9 s'est produit à 80 kilomètres au large des côtes nord-est de l'île d'Honshū au Japon.
Electrical switchgear was also disabled. Cs-134 is also produced and dispersed, it has a two-year half-life.