New evidence suggests that last week’s earthquake may have greatly exceeded the design basis standards for the North Anna nuclear plant. As the Bellingham Herald reported today:
A nuclear power plant in central Virginia may have experienced twice as much shaking as it was designed to withstand during last month’s rare East Coast earthquake, according to federal nuclear regulators, although no major damage has been found.
The data, as well as new details of the damage revealed at a Nuclear Regulatory Commission hearing Thursday, paint the clearest picture yet of how the magnitude 5.8 earthquake on Aug. 23 rocked a nuclear plant only a dozen miles from the epicenter in Mineral, Va.
North Anna, operated by Dominion Virginia Power, is the first nuclear power plant in the U.S. to undergo ground motion that exceeded its design.
The Nuclear Regulatory Commission said that the shaking in last week’s earthquake was significantly more that the plant was designed for:
NRC officials said preliminary seismic data from the U.S. Geological Survey shows the quake shook parts of North Anna at rates equal to 26 percent the force of gravity. The plant was designed to withstand jolts registering 12 percent and 18 percent the force of gravity for the sections built on rock and soil, respectively.