If this is true the game is over.
At Fukushima, workers have been pumping water into three reactors in a desperate bid to keep the fuel rods from melting down. But Lahey, who was head of safety research for boiling-water reactors at General Electric when the company installed the units at the plant, said his analysis of radiation levels suggested these attempts had failed at reactor two.
He said at least part of the molten core, which includes melted fuel rods and zirconium alloy cladding, seemed to have sunk through the steel “lower head” of the pressure vessel and on to the concrete floor below.
“The indications we have, from the reactor to radiation readings and the materials they are seeing, suggest that the core has melted through the bottom of the pressure vessel in unit two, and at least some of it is down on the floor of the drywell,” Lahey said. “I hope I am wrong, but that is certainly what the evidence is pointing towards.”
The major concern when molten fuel breaches a containment vessel is that it will react with the concrete floor of the drywell, releasing radioactive gases into the surrounding area. At Fukushima, the drywell has been flooded with seawater, which will cool any molten fuel that escapes from the reactor and reduce the amount of radioactive gas released.
Lahey said: “It won’t come out as one big glob; it’ll come out like lava, and that is good because it’s easier to cool.”
The drywell is surrounded by a secondary steel-and-concrete structure designed to keep radioactive material from escaping into the environment. But an earlier hydrogen explosion at the reactor may have damaged this.
No, hydrogen explosions at nuclear reactors are no big deal. After all, this video is reactor #3, not reactor 2 being described above. It’s not as if the explosion below could have damaged a building right next to it or anything.
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