by Paula C. Squires
Federal regulators responsible for monitoring the nation’s nuclear power plants say their inspection of North Anna Power Station following an Aug. 23 earthquake found no significant damage. However, the magnitude 5.8 quake that tripped North Anna’s two 980-megawatt nuclear reactors offline leaves some issues unresolved.
Eric Leeds, director of the NRC’s office of Nuclear Reactor Regulation, told an audience of about 150 at a public hearing in Louisa County in early October that there is no timeline for a restart. Dominion Virginia Power plant operators responded to the quake appropriately, protecting public health and safety, the NRC said. Yet, the agency has submitted about 100 questions to the utility regarding the plant’s performance, which must be answered before a restart can be authorized.
The hearing at North Anna’s information center in Louisa gave the NRC team a chance to weigh in with its independent review and provided the public with a chance to ask questions. The NRC got an earful. Several local residents wondered about the wisdom of restarting the reactors when nuclear power plants across the county are being asked to reassess their risks in the face of an unexpected seismic event, like the ground motion of the quake that exceeded North Anna’s licensed design. The August quake was the first time in the history of the U.S. nuclear industry that tremors knocked nuclear reactors offline.
The event was so unprecedented that the full NRC commission wants a briefing on what happened at North Anna and to review any restart issues. A meeting between Dominion Virginia Power, the full commission and its staff was scheduled for Oct. 21 at the NRC’s headquarters in White Flint, Md.
Greg Kolcum, North Anna’s senior NRC inspector who was in the plant’s control room when the quake occurred, said that the loss of offsite power “represented a degradation in plant safety. So we invited in the augmented inspection team.”
The NRC team identified some equipment issues that could raise red flags for other nuclear plants as they reassess earthquake risks. For instance, the plant’s seismic alarm panel lost some of its functions. Dominion has since installed a backup power supply. Also, the team discerned that seismic monitors located on plant structures may not have been in the best locations to accurately assess ground motion. Plus, there were no monitors in the dry cask storage area, with the casks moving as a result of the intensity of the quake.
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