– Melting of Japan plant’s fuel rods confirmed (Irish Times):
SCIENTISTS SAY the fight to bring Japan’s crippled nuclear power plant under control could take three months or more, even if not hampered by further earthquakes. The announcement comes after another day of aftershocks, including one with an epicentre about 25km from the Fukushima plant.
The head of the Atomic Energy Society of Japan, Takashi Sawada, said yesterday that fuel rods in reactors 1 and 3 have melted and settled at the bottom of their containment vessels, confirming fears that the plant suffered a partial meltdown after last month’s huge earthquake and tsunami.
– Fuel rod fragments at bottom of vessels (Japan Times):
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.
The fuel rods are being cooled by tons of water that is being manually injected into the reactors and their spent-fuel pools by truck. But if those operations are interrupted for two or three days by an aftershock or other unforeseen event, the reactors’ cores will again be at risk of melting down further, he said.
The nuclear safety committee, consisting of nuclear engineers and academics, compiled the analysis based on the data disclosed by Tokyo Electric Power Co. and the Nuclear and Industrial Safety Agency, the government’s nuclear watchdog. Earlier reports quoting experts giving the same explanation have been circulating in western media for a week.
The fuel rods in reactors 1, 2 and 3 are heavily damaged. Pieces of the rods melted into fragments about 1 cm wide or smaller and drifted to the bottom of the pressure vessels, the committee said.
Japanese nuclear scientists say if a cooling system can be put in place at the Fukushima Daiichi plant, stabilizing its nuclear fuel could take another 3 months.
The deputy head of the Atomic Energy Society of Japan, Takashi Sawada, released the projection by an informal group of 11 society members on Thursday.
He said data published by Tokyo Electric Power Company shows that parts of the fuel rods in reactors 1 and 3 have melted and settled at the bottom of the pressure vessels.
He said if the ongoing water injections continue, the current situation can be maintained.