From NBC News Washington (8/29/2011):
Despite being built to sustain more than the maximum expected shaking, last week’s earthquake may have exceeded the design parameters of the two nuclear reactors knocked offline.
That conclusion by Dominion Virginia Power and an independent government analysis prompted the Nuclear Regulatory Commission to send inspectors to the nuclear plant in Virginia.
The Dominion-operated North Anna Power Station 12 miles from the epicenter of the 5.8-magnitude quake in Louisa County temporarily lost power, but there was no significant damage to safety systems, according to the NRC. A low-level emergency was declared temporarily Tuesday after the incident.
The additional inspection should not be interpreted to mean the plant is less safe, the commission said Monday.
Nuclear power plants are built with margins of safety beyond the maximum expected shaking, and the damage detected so far at North Anna has been minimal.
(The article continues.)
In the meantime, Japan's Nuclear and Industrial Safety Agency now says there are 14 newly identified active faults near the nuclear facilities in Fukushima and Ibaraki Prefectures: 5 of them around TEPCO's Fukushima I and II Nuclear Power Plants, and 9 around the Tokai II Nuclear Power Plant operated by Japan Atomic Power Company and Tokai Fuel Reprocessing Facility operated by Japan Atomic Energy Agency. (From Kyodo News Japanese, 8/30/2011)
Don't worry, says NISA, they are all minor faults incapable of producing major earthquakes.