Regulators Aware For Years Of Understated Seismic Risks To Nuclear Plants

[jpak]

http://www.huffingtonpost.com/2011/03/18/nuclear-plants-regulators-risk_n_837504.html

Nearly 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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[Kolesar]

1. There is a fault line in the sedimentary bedrock hundreds of feet below Perry Nukular Power Plant

It was known before Cleveland Electric Illuminating Company built that plant.
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Earthquakes can occur in all sorts of locales. In January 1986, a late-morning quake measuring 4.96 on the Richter scale was blamed for cracks in the Perry Nuclear Power Plant on Lake Erie near Cleveland. At first, people thought it wasn’t a quake; speculation focused on an explosion somehow related to the Challenger space shuttle disaster or an attack on New York City. The newly licensed plant’s reactor was to be fueled for the first time the next day. Officials and the public were caught by surprise; few suspected Northeastern Ohio was in an active seismic zone. But it is. Experts determined that the quake’s epicenter was 11 miles from the plant, which has been dogged by controversy ever since.

[FBaggins]

3. The quake in Japan was about 10,000 times worse.

There's an issue of scale here.

[Kolesar]

4. But you said it was "the tsunami" in your other post on this thread...eom

[FBaggins]

5. And I think it probably was. I assumed that I didn't need to tell you that...

... Lake Erie isn't exactly prone to tsunami. :)

[FBaggins]

2. Do we know how much damage was done by seismic activity?

It's entirely possible that this entire event is from the tsunami, isn't it?

Obviously that was caused by the earthquake, but if we're doing an after-action report on what risks to mitigate in the future... the earthquake doesn't appear to be the problem.