Powerful Aftershock Complicates Japan’s Nuclear Efforts
By HIROKO TABUCHIand ANDREW POLLACK
Published: April 7, 2011TOKYO — The strongest aftershock to hit since the day of the March 11 earthquake and tsunami in Japan
rocked a wide section of the country’s northeast on Thursday night, prompting a tsunami alert, raising fears of new strains on the crippled Fukushima Daiichi nuclear plant and knocking out external power at three other nuclear facilities.
But the agency warned that slight changes in sea level were still possible, and it was unclear whether there was any damage along the coast. Many coastal communities were ravaged last month, and some are vulnerable because sea walls were breached and land levels sank.
Early Friday, injuries were reported in Sendai City and across the region, and blackouts continued in some areas, according to NHK. Five coal-powered power plants also shut down, adding to concerns over energy shortages.
Workers at the Fukushima Daiichi plant were told to take cover until the tsunami warning was lifted, but Japanese officials said at a news conference that water was still able to be pumped into three damaged reactors and a spent-fuel pool at a fourth in the crucial effort to keep their nuclear fuel cool. The plant’s cooling systems were knocked out by last month’s quake and tsunami.
Nitrogen also continued to be piped into the No. 1 reactor, the company said, in an effort to prevent a possible explosion. The Tokyo Electric Power Company, which runs the power station, said early Friday morning that it had found no new damage to the plant, though workers were checking to make sure there were no new radiation leaks. Monitoring posts around the plant were not showing any immediate increase in radiation levels, the company said.
A big aftershock is thought to pose an additional risk to the Fukushima plant because its containment structures, now filled with water that is highly radioactive, may be more vulnerable to rupture, according to an assessment by the United States Nuclear Regulatory Commission in late March.
Two other nuclear facilities — a fuel reprocessing plant at Rokkasho and a power plant at Higashidori, both in northern Aomori Prefecture — were running on emergency diesel generators after their external power was knocked out. The single reactor at Higashidori is shut down for maintenance, and all nuclear fuel has been transferred to spent fuel pools, which are being cooled by back-up diesel power, according to the operator, Tohoku Electric.
A third site, the Onagawa Nuclear Power Station in Miyagi Prefecture, lost two of its three external power systems, and cooling stopped temporarily at a spent fuel pool there, Tohoku Electric said. All three plants have been shut down since the March 11 quake, but power is needed to cool the nuclear fuel.Read More...
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