Virginia Nuclear Plants Trips Off During 5.8 Magnitude Earthquake

Wall Street Journal
August 27, 2011

Earthquake Triggers Reactor-Design Review
Rebecca Smith

The North Anna nuclear power plant near Mineral, Virginia tripped off during the 5.8 magnitude earthquake last week in Virginia. While there was no structural damage, the plant tripped out of service when sensitive electrical equipment apparently responded to high-frequency ground motion—common to Eastern quakes, but not of Western ones—as if it were an electrical disturbance. The lesson learned from the experience is that East Coast quakes have special characteristics that need to be factored into construction of nuclear plants. The two reactors at North Anna were already on a list of 27 reactors that the Nuclear Regulatory Commission has identified as in the greatest need of additional seismic analysis. A subsequent article by Rebecca Smith in the Wall Street Journal reports that the 5.8 magnitude earthquake may have exceed the levels for which the plant was designed. If this preliminary finding proves to be valid, the plant’s owner, Dominion Resources, would need special approval from theNRC to return the plant to service. According to the Wall Street Journal, the NRC is in midst of a multiyear analysis of the effects of earthquakes on reactors in the central and eastern U.S., in the belief that earthquake risks there may have been underestimated.