Radioactive water spilled from pools holding spent nuclear fuel rods at the Onagawa power plant in Miyagi Prefecture following the strong earthquake late Thursday, the nuclear safety agency said Friday.
At the crisis-hit Fukushima Daiichi nuclear power plant or at another plant in Fukushima Prefecture, meanwhile, no new problems have surfaced since the magnitude 7.4 aftershock of the deadly March 11 quake.
While the spent fuel pools at the Onagawa plant and the Higashidori nuclear power station in Aomori Prefecture, both operated by Tohoku Electric Power Co., lost their cooling functions for 20 to 80 minutes after the quake, the temperature hardly rose, the Nuclear and Industrial Safety Agency said.
A small amount of contaminated water spilled on the floor was observed inside the buildings at all three reactors at the Onagawa plant, which has suspended operations since the mega earthquake and tsunami last month, according to the agency.
In all, water spilled or leaked at eight sections of the plant as a result of the 11:32 p.m. quake, according to Tohoku Electric.
As much as 3.8 liters of water leaked at one of them, with the highest level of a radioactive isotope -- 5,410 bequerels per kilogram -- found in the spilled water on the floor beside a spent fuel pool in the building housing the No. 1 reactor.
A spent nuclear fuel disposal facility in the village of Rokkasho, Aomori Prefecture, lost external power supply and switched to an emergency generator but power was restored at 9:44 a.m. Friday, according to the agency.
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