NRC Inspection Ordered After Indication Quake May Have Exceeded North Anna Design Limits

Centered just 12 miles from the North Anna nuclear plant, last week’s earthquake in Virginia may have exceeded the facility’s design limits, the Nuclear Regulatory Commission indicated Monday.

In a release, the agency said it has dispatched an augmented inspection team to gather further data on the plant, the earthquake and the wider risks such events pose to U.S. reactors.

NRC“No significant damage to safety systems has been identified, but Dominion has reported to the NRC that initial reviews determined the plant may have exceeded the ground motion for which it was designed. This determination is in line with NRC’s preliminary independent analyses, although data is still being collected and analyzed to determine the precise level of shaking that was experienced at key locations within the North Anna facility. The company and the NRC will continue to carefully evaluate information to determine if additional actions may be necessary,” the release read.

Last Tuesday’s 5.8 magnitude earthquake caused both Westinghouse pressurized water reactors at North Anna to trip. It also disabled the plant’s external power supply, which necessitated the use of diesel generators until power lines were restored a few hours later. Both units remain offline as Dominion and NRC personnel, including a seismic expert and a structural expert, inspect the facility and analyze data on the strength and effects of shaking at the plant. They will be joined by the augmented inspection team Tuesday.

“The fact that we’re sending an AIT should not be interpreted to mean that Dominion staff responded inappropriately or that the station is less safe as a result of the quake,” NRC Region II Administrator Victor McCree was quoted as saying in the release. “An AIT provides us with the resources needed to completely understand all the effects at North Anna and gather important information for the NRC’s continuing evaluation of earthquake risk at all U.S. nuclear plants.”

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