Scientists warn of risks from spent-fuel cooling pools and plutonium-rich, mixed-oxide fuel inside one nuclear reactor, even as the No. 1 and No. 3 reactors appear to be coming under control.
Bullit Marquez / AP
Two Japanese nuclear reactors whose cooling systems were knocked out following an earthquake and tsunami were joined Monday morning by a third reactor that lost its cooling system. All three now are assumed at risk of partial or total meltdowns of their radioactive-fuel cores.
Still, one US nuclear expert said there was at least a glimmer of positive news emerging, with two of the three reactors showing signs of coming under control.
"Units No. 1 and No. 3 seem to be trending to more stable conditions and increasing safety margins," said Dave Lochbaum, a nuclear engineer and director of the Union of Concerned Scientist Nuclear Safety Program (UCS), a US nuclear safety watchdog group, in a conference call with reporters. No. 2, however, remains in an unstable, volatile situation, he said.
Two explosions over the weekend – apparently due to hydrogen buildup – ripped apart buildings housing the No. 1 and No. 3 reactors at the Fukushima I plant, about 150 miles north of Tokyo and owned by the Tokyo Electric Power Co. (TEPCO). The explosions injured workers and complicated efforts to flood the reactors to keep them cool.
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