RICHMOND — Dominion Virginia Power said Tuesday that it expected to have its North Anna 1 nuclear power plant back up at full power quickly.
“We expect the unit to be at 100 percent soon,” company spokesman Richard Zuercher said Tuesday, though he would not, for competitive reasons, say specifically when it would be in full operation.
Dominion Virginia Power detected a leak Monday morning in an air line that is part of one of the plant’s generation systems, Zuercher said. As a result, the company reduced the reactor’s power to fix the line.
The line is not part of the plant’s nuclear safety systems, according to a U.S. Nuclear Regulatory Commission spokesman.
The NRC said the unit was manually taken from 100 percent of operating capacity to about 4 percent while repairs were made Monday afternoon.
The small line carries air under pressure to hold a main steam valve open during normal operations.
The valve is designed to close and stop steam flowing from a steam generator to the plant’s power turbine in the event of a steam-line rupture. Stopping rapid steam loss protects the reactor from cooling too rapidly in a shutdown.
Though Richmond-based Dominion Virginia Power removed the reactor from service, the nuclear chain reaction was maintained during the outage, with reactor power at about 4 percent, Zuercher said.
The repairs were quickly completed Monday, and workers began powering Unit 1 back up, NRC spokesman Joey Ledford said.
Dominion Virginia Power reconnected the Louisa County plant at reduced power to the electrical grid at about 9 a.m. Tuesday, Zuercher said.
Unit 1 was operating at 8 percent Tuesday morning, according to the once-a-day figure provided by the NRC.
Unit 2 continued to operate at full power.
Having the 980-megawatt unit out of service can cost the company, the state’s largest electric utility, as much as $500,000 to $1 million a day for replacement power.
The leak found Monday led to the second power reduction in one of the units at North Anna since they were restarted in November after being knocked offline by a magnitude-5.8 earthquake Aug. 23.
But less than a week after Unit 2 was restarted, power in the unit was reduced to 98 percent so workers could check out what appeared to be a faulty resistor on a feedwater-flow instrument. The utility returned the unit to full power within days.
Macenka and Bacque report for the Richmond Times-Dispatch.
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