North Anna Nuclear Generating Station (photo: dougward)

In what feels like a Friday news dump that goes to 11, the US Nuclear Regulatory Commission has given its approval to restart Dominion Virginia Power’s North Anna nuclear power facility. The decision came late in the day on a holiday–Veterans Day, 11/11/11.

As previously noted, the reactors at North Anna scrammed during the Mineral, VA earthquake of August 23. It was later shown the power plant sustained shaking well beyond its design criteria. Several spent fuel storage casks moved one to four inches, and other storage containers showed what was termed cosmetic damage (namely, cracks), but plant operators contend that the nuclear reactors sustained no “functional” damage.

What constitutes “functional” now remains to be seen. The fact is there was no official protocol–no “checklist”–for evaluating a nuclear facility after it experienced a seismic event such as this. The NRC’s inspectors have essentially been inventing that inspection regime on the fly as they surveyed the North Anna plant. Dominion has been pressing for permission to restart since shortly after the quake.

Of concern, beyond the cracks and dancing dry casks, has been the integrity of the containment buildings and, more specifically, the pipes and couplings that ensure that the reactors can be properly cooled once the cores are allowed to again heat up. Questions about the state of underground pipes were expressed right after the earthquake by watchdogs such as Paul Gunter, and those same buried pipes were cited as recently as last week when explaining the ongoing delay to the restart OK.

North Anna’s reactors were initially thought to have shut down when the cooling systems lost power from the electrical grid, soon after the Virginia quake. Three backup diesel generators provided power to the safety systems until power could be restored (a fourth generator failed). Later, however, it was discovered that the shaking itself caused the reactors to scram–a fast emergency shutdown sometimes compared to slamming the brakes on a speeding car.

How the NRC and its inspectors resolved questions about what constituted a passing grade after a never-before-seen event remains to be seen. Until then, it appears the NRC will do the regulatory equivalent of keeping its fingers crossed:

Eric Leeds, director of the NRC’s Office of Nuclear Reactor Regulation, said in a statement. “We’re satisfied the plant meets our requirements to restart safely, and we’ll monitor Dominion’s ongoing tests and inspections during startup of both reactors.”

Let’s hope inspectors work holidays.