NRC inspectors say earthquake did not cause significant damage to North Anna
- October 4, 2011
By Paula C. Squires
Federal regulators responsible for monitoring the nation’s nuclear power plants said yesterday that their inspection of North Anna Power Station following an Aug. 23 earthquake found no significant damage. However, the unprecedented event of a magnitude 5.8 quake that tripped North Anna’s two 980-megawatt nuclear reactors offline leaves some issues unresolved, and the agency plans to begin a new round of inspections on Wednesday before it will decide on a restart of the reactors.
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 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 new round of inspections are scheduled from Oct. 5 through Oct. 14. “The bottom line is that we won’t allow the plant to restart unless we think it’s safe. There are many issues to resolve going forward,” Leeds said.
Yesterday’s 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 Aug. 23 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 has been 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 yesterday that the loss of offsite power “represented a degradation in plant safety.
So we invited in the augmented inspection team.”
The NRC team did identify 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.
Victor McCree, an NRC regional administrator, said in an interview that the agency may begin requiring nuclear power plants to install what is known as a free field seismic detention system. It would be installed away from a plant to better measure earthquake activity. Jim Norvelle, a spokesman for Virginia Dominion Power, said Dominion already has installed one in a field away North Anna’s buildings and structures.
The NRC said it also observed anomalies on some safety-related equipment instruments that raised questions about equipment qualification. Altogether it said there were seven unresolved items that warranted further NRC review.
Ronald E. Stauffer, a lawyer who lives at nearby Lake Anna, questioned why the NRC wouldn’t hold the plant to the same higher margin of safety during a restart that would be required if Dominion’s application for a third nuclear reactor at the site is ever approved. “One of your key findings is that the ground motion exceeded the parameters for which the plant was designed. … How can you permit units 1 and 2 to be restarted without first upgrading them to meet the higher safety standard?”
The fact that North Anna sustained no significant damage shows that the plant has a safety margin beyond what’s its licensed for, responded Leeds.
Another speaker from Charlottesville asked if a future earthquake could damage the plant’s cooling ponds, hurting their ability to cool the reactor. McCree said North Anna could lose its cooling lake and still be able to maintain the plant’s safety.
David Heacock, chief nuclear officer for Dominion Resources, added that North Anna is equipped with steam-driven pumps that could cool the reactors indefinitely. Also, Heacock told the audience that while the ground motion of the earthquake exceeded the plant’s design, the force didn’t exceed the plant’s duration design. The quake lasted for about three seconds, he said, and the plant is designed to take 15 to 30 seconds of strong motion. “At no time was the public at any risk … There is tremendous margin at the plant. Going forward, we can show that the plant is safe,” he said.
Asked how long Dominion Virginia Power could be without the two nuclear reactors, which generate about 22 percent of the electricity for Dominion’s state customers, Heacock said other power sources are readily available on the open market. Right now, with mild weather, the cost has not been great. However, if the reactors remain down for a protracted period, Dominion could seek to recoup from customers the additional charges it has to pay for fuel, Heacock said. Dominion Virginia Power, a subsidiary of Dominion Resources Inc., is the state’s largest utility with about 2.3 million Virginia customers.
A couple of speakers asked the NRC if they could obtain the original environmental impact statement on North Anna, which was built in the late 1970s. Recent news reports have indicated that the station site was built on a geologic fault, a fact not initially disclosed to the NRC, and which resulted in Dominion paying a fine of nearly $35,000. At the time, the fault had not been active in years. Playing off that history, a local group has named itself “Not on our fault line.” Its members donned T-shirts with that slogan and were among those at yesterday’s hearing.
The NRC’s full inspection report will be available to the public at the end of the month. Norvelle said the hearing “went as expected. It was informative… We are working toward restart and believe there will be a restart.”