http://www.huffingtonpost.com/2011/03/18/nuclear-plants-regulators-risk_n_837504.htmlNearly six years before an earthquake ravaged Japan’s Fukushima Daiichi nuclear power plant, U.S. regulators came to a sobering realization: seismic risks to nuclear plants in the eastern two-thirds of the country were greater than had been suspected, and engineers might have to rethink reactor designs.
Thus began a little-noticed risk assessment process with far-reaching implications despite its innocuous-sounding name: Generic Issue 199. The process, which was supposed to have been finished nearly a year ago, is still under way. It is unclear when it will be completed.GI-199, as it is known, was triggered by new geophysical data and computer models showing that, as the Nuclear Regulatory Commission put it in an August 2010 summary document, “estimates of the potential for earthquake hazards for some nuclear power plants in the Central and Eastern United States may be larger than previous estimates.”
Data from the U.S. Geological Survey and other sources suggest, for example, that “the rate of earthquake occurrence … is greater than previously recognized” in eastern Tennessee and areas including Charleston, S.C., and New Madrid, Mo., according to the NRC document. There are 11 reactors in Tennessee, South Carolina and Missouri.
GI-199, a collaborative effort between the NRC and the nuclear industry, has taken on new urgency in light of the crisis in Japan. “Updated estimates of seismic hazard values at some of the sites could potentially exceed the design basis” for the plants, the NRC document says.
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