Melted fuel rod fragments have sunk to the bottoms of three reactors at the Fukushima No. 1 power plant and could theoretically burn through the pressure vessels if emergency water-pumping operations are seriously disrupted, the Atomic Energy Society of Japan said Friday.
If too many of the melted fuel fragments puddle at the bottom, they can generate enough concentrated heat to bore a hole in the pressure vessel, which would result in a massive radioactive release to the environment..
"It will take at least two or three months ... until the situation of fuel rods is stabilized" said Takashi Sawada, vice chairman of the nuclear body.