Fukushima Disaster

The earthquake and tsunami that attacked Japan on March 11, 2011 caused the Fukushima nuclear power plant to collapse. It was the largest of the 2011 Japan nuclear accidents. A series of equipment failure, nuclear  meltdowns and release of radioactive materials made for the largest nuclear accident Japan has seen since the 1986 Chernobyl disaster. Multiple reactors and spent fuel pools make the disaster even more complex.

Emergency generators started up to run the control electronics and water pumps needed to cool the reactors. The entire plant was flooded by the 49 ft tsunami wave, including generators and the electrical switchgear in the reactor basements and externals pumps for supplying cooling seawater. At the time of the quake, reactors 5 and 6 had been shut down for planned maintenance and reactor 4 had been de-fuelled. The rest of the reactors automatically shut down once the earthquake hit.

Connection to the electrical grid was broken as the Tsunami destroyed power lines. Power for keeping the plant cool was destroyed and the reactors started overheating. Extra assistance would be needed to keep the plant cool from the flooding and earthquake damage. Reactors 1, 2 and 3 experienced full meltdown in the days and hours that followed the natural disaster. Hydrogen explosions destroyed the upper housing of reactors 1,3 and 4 with explosions at reactors 1 and 3, damaging the remains of reactor 2 and multiple fire outbreaks in reactor 4.

Fuel rods stored pools in each reactor began to overheat as water levels dropped. Radioactivity releases led to a 12 mile radius evacuation around the plant. Workers suffered radiation exposure and were temporarily evacuated. On March 20 grid power was restored in parts of the plants but reactors 1-4 remained inactive due to damaging flooding, fires and explosions. Areas where repairs were needed through the basement of the plant remained inaccessible because of flooding with radioactive water. It wasn’t until May 5th that workers were finally able to enter the reactor safely since the accident. Areas in Nothern Japan, 30-50km away from the plant showed radioactive caesium levels high enough to cause concern. Food grown in the area was banned from being sold. Iodine and Caesium levels released from those isotopes from Fukushima are of the same magnitude from Chernobyl in 1986. Officials advised that tap water used to prepare food for infants was not used.

Japanese officials assessed the accident as a level 4 on the International Nuclear Event Sales, although view from other agencies thought it should be much higher. Eventually the INES level was raised to a 5 and again to a 7. The Japanese government was criticized for poor communication with the public and improvised clean-up. A workforce in the hundreds or even thousands would take years to even decades to clean up the area.

http://www.independent.co.uk/news/world/asia/why-the-fukushima-disaster-is-worse-than-chernobyl-2345542.html

http://www.naturalnews.com/032035_Fukushima_physics.html

http://www.guardian.co.uk/world/2011/sep/09/fukushima-japan-nuclear-disaster-aftermath