1. Three of the six reactors of Fukushima No. 1 had a complete core meltdown a few days after the tsunami hit. The molten fuel penetrated not only through the bottom of the thick pressure vessel, but also poked holes at the bottom of the containment vessel, thus releasing fission materials into the environment. The meltdown itself started at 11p.m. on the day of the tsunami, March 11, 2011.
2. As expected, the meltdown caused the fuel cladding material, zircaloy (zirconium alloy), to react with vapor and to create large quantities of hydrogen and zirconium oxide, which caused the catastrophic hydrogen explosion that blew out three reactor buildings. The hydrogen explosion took place on March 12, 14 and 15. The Japanese Government did not admit to the meltdown until three months later, nor did they admit to the damage to the containment vessels until a half year later. Our government tried to hide this important information for some reason, though judging from the amount of fission material released and from the size of the hydrogen explosion, the meltdown of the entire core was undeniable for anyone who has studied reactor engineering.
3. The earthquake on March 11 damaged all of the five independent external power supply systems, and the 15-meter-high tsunami damaged all of the pumps and motors of the main and emergency cooling systems that were constructed along the shore line, thus disabling the cooling system that pumps in sea water.
4. The tsunami also sent massive amounts of water into the reactor buildings and the turbine housing, thus soaking the emergency diesel engines and batteries, which were stored in the basement of these buildings. This meant that all sources of emergency backup power stored in the basement of the reactors were totally destroyed.
5. There was an air-cooled diesel engine sitting atop a hill close to Reactor No. 6. Its airfins were too big to fit into the basement and was luckily placed outside, and as such, this engine started to generate electricity. With a pump brought in from outside, it started to cool not only Reactor No. 6, but had enough power to cool Reactor No. 5. Of the 13 emergency generators associated with the six plants, this was the only one of the three air-cooled backups, and hence not dependent on water as the heat sink. This air-cooled diesel engine was the only one not entirely submerged in water, but in fact at one point the water level did reach up to half its height. A few weeks later Reactors No. 5 and No. 6 were brought to a cold shutdown.
6. The buildings of reactors No. 1 and No. 3 were blown away by an explosion of hydrogen generated by the core meltdown. Reactor No. 4 eventually exploded, though its core had no fuel inside due to a periodic inspection that meant the fuel rods were stored elsewhere. It turned out that the Reactor No. 4's building filled with hydrogen that leaked from Reactor No. 3 through their common gas release ducts. Reactor No. 2 escaped from the massive explosion, although its core had completely melted. Its windows were blown away most likely by the explosions from neighboring reactors No. 1 and No. 3 and the hydrogen inside Reactor No. 2 escaped into the air. More
