North Anna nuclear reactor automatically trips offline, prompting an investigation
- October 24, 2012
One of two nuclear reactors at Dominion Virginia Power’s North Anna Power Station in Louisa County automatically shut down early Wednesday, prompting the company to notify the Nuclear Regulatory Commission of an unusual event condition.
However, by mid-day Richard Zuercher, manager of nuclear public affairs, said Dominion would request to retract that notification, because all systems functioned as designed to shut the unit down safely.
“We will be retracting our Notification of Unusual Event Classification as allowed under NRC regulations,” he said in an email to Virginia Business.
In its preliminary report to the NRC, Dominion said that Unit 2 tripped off automatically at 1:47 a.m. The company notified the NRC at 2:40 a.m. The shutdown occurred less than a week after Unit 2 had been restarted, after being offline for two weeks so repairs could be made to the seals of reactor coolant pumps.
Zuercher said the unit shut down Wednesday when four valves that govern the flow of steam that spins the turbine generator simultaneously closed. “The closing of the values caused the reactor to shut down,” he said. Station personnel and North Anna’s NRC resident inspector are investigating to determine what caused the valves to close.
Joey Ledford, a spokesman for the NRC in Atlanta, said “Our resident inspector will look at what happened, their response and whether any follow up is necessary.”
Ledford said it isn’t unusual for nuclear units to automatically trip offline. “That’s what they are designed to do. If something happens, they’re designed to shut themselves down.”