Profile photo of 74

Fukushima Dai-ichi

I’m pretty certain they have know a long time the bottom melted out.

At an estimated eighty minutes after the March 11, 2011 tsunami strike (which caused various nuclear accidents, the worst of which being the Fukushima Daiichi nuclear disaster), the temperatures inside Unit 1 of the Fukushima Daiichi Nuclear Power Plant reached 2300 ˚C to 2500 ˚C, causing the fuel assembly structures, control rods and nuclear fuel to melt and form corium. The reactor core isolation cooling system (RCIC) was successfully activated for Unit 3, however the Unit 3 RCIC subsequently failed and at about 09:00 on March 13 the nuclear fuel had melted into corium. Unit 2 retained RCIC functions slightly longer and corium is not believed to have started to pool on the reactor floor until around 18:00 on March 14.[46]