Eastern US Earthquake shook North Anna nuclear plant in Virginia more than it was designed to handle

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Last month's record earthquake in the eastern United States may have shaken a Virginia nuclear plant twice as hard as it was designed to withstand, a spokesman for the U.S. nuclear safety regulator said on Thursday. But Dominion Resources told the Nuclear Regulatory Commission that the ground under the plant exceeded its "design basis" only by about 10 to 20 percent, and it plans to prove in the next month that its reactors are safe to restart. The discrepancy is one of many items the NRC and company must deal with, in the first instance in which an operating U.S. nuclear power plant has experienced a quake beyond its design parameters. The NRC must sign off on Dominion's restart plans for the North Anna plant, about 12 miles from the quake's epicenter -- and determine how it will make that decision.

Last month's record earthquake in the eastern United States may have shaken a Virginia nuclear plant twice as hard as it was designed to withstand, a spokesman for the U.S. nuclear safety regulator said on Thursday.

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But Dominion Resources told the Nuclear Regulatory Commission that the ground under the plant exceeded its "design basis" only by about 10 to 20 percent, and it plans to prove in the next month that its reactors are safe to restart.

The discrepancy is one of many items the NRC and company must deal with, in the first instance in which an operating U.S. nuclear power plant has experienced a quake beyond its design parameters.

The NRC must sign off on Dominion's restart plans for the North Anna plant, about 12 miles from the quake's epicenter -- and determine how it will make that decision.

"You have the unique opportunity of being at the cutting edge -- and whenever I say that, usually I get a response like, 'It feels like a bleeding edge,'" said Jack Grobe, deputy director of the NRC's Office of Nuclear Reactor Regulation, to officials from Dominion.

"It's not entirely clear to us exactly what we need in this submittal from you. A summary may not do it," Grobe said near the end of an exhaustive three-hour engineering face-off between a dozen top officials from each side.

Neither the company nor the NRC have found signs of serious damage to safety systems at the North Anna nuclear plant, although inspections by both sides continue.

NRC experts from a variety of nuclear engineering disciplines peppered Dominion counterparts with questions about the impact to fuel in the core, the strength of welds in plant steels, and the resilience of underground pipes.

Photo credit: Dominion Power

Article continues: http://www.reuters.com/article/2011/09/08/us-usa-nuclear-dominion-idUSTRE7877MG20110908