Two nuclear reactors that have remained shut down since the Aug. 23 earthquake can't be restarted until Dominion Virginia Power receives approval from the U.S. Nuclear Regulatory Commission, the federal agency said Friday.
The NRC sent a letter to Dominion confirming that the energy company won't restart the nuclear reactors at its North Anna Power Station about 11 miles from the quake's epicenter until it is given permission from the agency. Dominion says seismic vibrations from the 5.8-magnitude earthquake caused the plant's two reactors to shut down.
The agency is “reviewing Dominion's information to ensure North Anna's systems will be able to keep the public safe and the plant won't start up again until we're satisfied on that point,” Eric Leeds, director of the NRC's office of nuclear reactor regulation, said in a statement.
In early September, the NRC said preliminary data from the U.S. Geological Survey showed the earthquake caused peak ground movement about twice the level for which the plant about 50 miles northwest of Richmond was designed.
Dominion officials have told the NRC that ground movement under the plant exceeded its “design basis” -- the first time that has occurred at an operating U.S. nuclear plant. But Dominion said its seismic data from the site showed shaking at much lower levels than those reported by the USGS.
“In multiple, detailed inspections, we have found no significant damage at North Anna caused by the quake. We will continue to work with the NRC as it performs its necessary inspections,” said Dominion spokesman Jim Norvelle, who said the NRC letter is a formal step in the process of restarting the reactors.
During a media tour in early September, Dan Stoddard, senior vice president of nuclear operations for Dominion, said the company wouldn't restart the reactors until it's convinced it is safe. Stoddard said the damage was only cosmetic.
Inspections conducted after the quake show there is a safety margin that exceeds the design basis. With few exceptions, Dominion said safety components evaluated at the plant could withstand shaking even greater than that recorded by the Virginia earthquake.
A public hearing to discuss the findings of the agency's inspections is scheduled for Monday. Various groups have said the earthquake is a wake-up call about the danger of another event in the area and are asking that Dominion retrofit the reactors at the plant to higher earthquake safety standards.
The NRC has said it plans to order all U.S. plants later this year to update their earthquake risk analyses, a complex exercise that could take two years for some plants to complete. The review, launched well before the East Coast quake and the Japan nuclear disaster in March, marks the first complete update to seismic risk in years for the nation's 104 existing reactors, despite research showing greater hazards.
The two North Anna reactors are among 27 in the eastern and central U.S. that may need upgrades, according to a preliminary NRC review.
When fully operational, the Virginia facility produces enough energy to power about 450,000 homes. Dominion is using other power sources in its generation system to make up for the plant being offline.
The company is still weighing the addition of a third reactor at the Louisa County power plant but has not yet committed to move forward with the project. The company will reassess when it receives operating approval from the NRC, expected in 2013.
Dominion Virginia Power is a subsidiary of Dominion Resources Inc., one of the nation's largest producers and transporters of energy and has the nation's largest natural gas storage system. It serves retail customers in 15 states.