Dream Theater Nice

The Fukushima Daiichi nuclear is a series of equipment failures, nuclear meltdowns, and releases of radioactive materials at the Fukushima I Nuclear Power Plant, following the 9.0 magnitude Tōhoku earthquake and tsunami on 11 March 2011.[6][7] The plant comprises six separate boiling water reactors maintained by the Tokyo Electric Power Company (TEPCO). This accident is the largest of the 2011Japanese nuclear accidents arising from the Tōhoku earthquake and tsunami, and experts consider it to be the second largest nuclear accident after the Chernobyl disaster, but more complex as multiple reactors are involved.[8]

At the time of the quake, Reactor 4 had been de-fueled while 5 and 6 were in cold shutdown for planned maintenance.[9] The remaining reactors shut down automatically afterthe earthquake, with emergency generators starting up to run the control electronics and water pumps needed to cool reactors. The plant was protected by a seawall designed to withstand a 5.7 m (19 ft) tsunami but not the 14 m (46 ft) maximum wave which arrived 41–60 minutes after the earthquake.[10] The entire plant was flooded, including low-lying generators and electrical switchgear in reactorbasements and external pumps for supplying cooling seawater. The connection to the electrical grid was broken as the Tsunami destroyed the power lines. All power for cooling was lost and reactors started to overheat, owing to natural decay of the fission products created before shutdown. The flooding and earthquake damage hindered external assistance.

In the hours and days that followed, reactors1, 2 and 3 experienced full meltdown.[11][12] Hydrogen explosions destroyed the upper cladding of the buildings housing Reactors 1, 3, and 4; an explosion damaged the containment of reactor 2;[13] multiple fires broke out at Reactor 4. With the remnants of its reactor core fallen to the bottom of its damaged reactor vessel, Unit 1 continues to leak cooling water approaching three months after theinitial events; similar conditions are hypothesized to exist at the other two melted-down reactors in the complex.[14]

Despite being shut down at the time of the earthquake and tsunami, Reactors 5 and 6 began to overheat. Fuel rods stored in pools in each reactor building began to overheat as water levels in the pools dropped. Fears of radioactivity releases led to a 20 km (12 mi) radiusevacuation around the plant while workers suffered radiation exposure and were temporarily evacuated at various times. One generator at Unit 6 was restarted on 17 March allowing some cooling at Units 5 and 6 which were least damaged. Grid power was restored to parts of the plant on 20 March, but machinery for Reactors 1 through 4, damaged by floods, fires and explosions, remained inoperable.[15]Flooding with radioactive water continues to prevent access to basement areas where repairs are needed.[16] However, on 5 May, workers were able to enter reactor buildings for the first time since the accident.[17]

Measurements taken by the Japanese science ministry and education ministry in areas of northern Japan 30–50 km from the plant showed radioactive caesium levels high enough to causeconcern.[18] Food grown in the area was banned from sale. Based on worldwide measurements of iodine-131 and caesium-137, it was suggested that the releases of those isotopes from Fukushima are of the same order of magnitude as those from Chernobyl in 1986;[19][20][21] Tokyo officials temporarily recommended that tap water should not be used to prepare food for infants.[22][23] Plutonium contamination hasbeen detected in the soil at two sites in the plant,[24] although further analysis revealed that the detected density are within limits from fallout generated from previous atmospheric nuclear weapons tests.[25] Two workers hospitalized with non-life threatening radiation burns on 25 March had been exposed to between 2000 and 6000 mSv of radiation at their ankles when standing in water in Unit...