2. Reactor 4 is building 7, demolished by explosives. [爆発物によって破壊された] Reactor 4 had been defueled and was undergoing replacement of it's internal stainless steel shroud, yet blew it's containment anyway. That is the FINAL smoking gun, an empty reactor is inert, and cannot produce an explosion, yet one happened at 4 that was so powerful it destroyed the structure leaving it in danger of falling over. Overheated open fuel pools cannot produce hydrogen because in an open fuel pool the water boils off at 100 Celsius, and won't be present in pressurized form at 2,000 degrees Celsius to liberate it's hydrogen by losing it's oxygen to the zircon cladding in the fuel rods. The rods will prefer the free oxygen in the air and burn long before attempting to claim the oxygen in whatever humidity there might be. The fact that the rods can catch fire only enforces the fact that they cannot release hydrogen in open air the way they can in a reactor. If you entertain the fantasy that they could, another problem against buildup presents itself - the hydrogen would be safely burned the moment it was created on the surface of the superheated rods. There would be no buildup. Fuel rods are many orders of magnitude below incapable of going supercritical also, even if totally melted down. The explosion at #4 was flatly impossible.

Reactor 4's dome was removed for defueling. Drone photos prove it. This dispels the rumors surrounding unit 4's explosion. Some people have said that this reactor was secretly in operation to enrich plutonium. This photo proves it was disassembled for shroud replacement as stated. Tepco is going out of it's way trying to explain the explosions, especially at reactor 4, because they did indeed occur, so an explanation is needed. As a result, they are giving reasons that cannot happen, just to say something.

have fun debunking, science wonks!

'The history of public debt is full of irony. It rarely follows our ideas of order and justice.' Thomas Piketty