The NRC says the station's two units shut down automatically when the facility lost offsite power during the quake, and emergency diesel generators kicked in to cool the reactors until offsite power was restored.

The station remains shut down, however, as data from the quake is reviewed to assess the possible overall impact.

The NRC notes that no significant damage to safety systems has been found, but the company that operates the plant, Dominion, and the NRC agree that initial reviews show further analysis is necessary. The NRC says regulations require that the station not start up until it can demonstrate that no functional damage occurred to those features needed for continued safe operation.

“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,” says NRC Region II Administrator Victor McCree. “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.”

The AIT will include experts from the NRC and from the North Anna station. The AIT will hold an exit meeting with Dominion after the inspection is complete to discuss its preliminary findings, the NRC says.

As noted in an April NU story, nuclear plants in the U.S. are insured under a two-tier system: a private-liability insurance tier made available by a pool of U.S. insurers called American Nuclear Insurers, and a second tier funded by assessments on nuclear power plant operators. Congress created the program outlining this two-tier system in 1957 through the Price-Anderson Act.

For the first tier, policy limits are currently $375 million. Capacity for the second tier currently stands at around $12.2 billion.

A mutual insurance company formed by plant operators covers plants' physical premises.