* North Anna reactors shut after earthquake in August * NRC must grant permission before North Anna returns * NRC says inspections of plant are ongoing By Scott Disavino and Ayesha Rascoe Oct 21 (Reuters) - Virginia-based power company Dominion said on Friday it was ready to restart the 1,806-megawatt North Anna nuclear power plant, but federal nuclear regulators said their safety review of the plant had yet to end. The plant shut down automatically on Aug. 23 when an earthquake struck central Virginia. The epicenter was about 11 miles (17.5 km) from the station and about four miles underground. The quake marked the first time an operating U.S. nuclear plant experienced a tremor that exceeded its design parameters. The U.S. Nuclear Regulatory Commission (NRC) on Friday reiterated its commitment to ensuring that the plant is totally safe before it allows operations to resume. "The bottom line is that the NRC will not authorize restart until we are satisfied that the plant can be operated while protecting public health and safety," Bill Borchardt, NRC executive director of operations, said at a commission hearing. The restart process for North Anna has taken place in the shadow of the nuclear disaster that roiled Japan in March when an earthquake and tsunami damaged the Fukushima Daiichi nuclear power plant, causing reactor fuel meltdowns and radiation releases. 'DESIGN BASIS ISSUE' Dominion said both North Anna units are ready to restart once the agency completes its independent review, analysis, and on-site inspections and grants permission. "The lack of damage from the Aug. 23 earthquake clearly demonstrated that North Anna's true seismic capability is greater than design basis of the station," David Heacock, president and chief nuclear officer of Dominion, said in a release. "While the quake lasted about 25 seconds, only 3.1 seconds of intense motion occurred. The station could have withstood significantly more," Heacock said. The NRC also said so far it had found no significant damage at the plant. However, some commissioners at the nuclear regulator questioned the possible implications of this event for the agency's regulatory regime. "We have a design basis issue ... if we know the design basis has been exceeded, how do you continue to operate unless you make that change in design basis?" NRC commissioner William Magwood said at the meeting. At the NRC's request, Dominion said it agreed to perform additional seismic analysis on certain components after restart to quantify and further demonstrate they can meet specific seismic requirements. Dominion said it spent about $21 million on its inspection, testing and analysis program, including repairs, since the earthquake occurred. Dominion has said the 903-MW North Anna Unit 1 has been ready to return to service since the end of September. Dominion conducted a planned refueling on the 903-MW North Anna Unit 2 during its downtime.