A nuclear power plant has reported that last week’s 5.8-magnitude earthquake may have created stronger shaking that it was designed to withstand, prompting the Nuclear Regulatory Commission to send additional inspectors to the Virginia facility this week.
“We’re perplexed,” said Jim Norvelle, spokesman of Dominion, which operates the North Anna nuclear plant, located about 10 miles from the quake’s epicenter in Mineral, Va. He said the plant’s engineers had estimated that the two reactors, which went online in 1978 and 1980, could withstand quakes of 5.9- to 6.2-magnitude.
That estimate is now in question. The difference may be lost in the translation from magnitude to ground motion. Although earthquakes are routinely measured in magnitude, or energy released, the NRC requires the nation’s 104 nuclear reactors to withstand a predicted level of ground motion, or acceleration — something calculated as a g-force. The NRC has cautioned that it’s not easy to convert the two.