The Pilgrim Nuclear Power Station manually shut down while at reduced power during a condenser cleaning operation, a federal nuclear official said.
The condenser takes water from Cape Cod Bay and uses it to cool steam produced in the reactor to spin the turbine and generate electricity, according to officials with the Nuclear Regulatory Commission (NRC) and Entergy Nuclear, the company that owns the Plymouth, MA, plant.
During the cleaning, the condenser began to lose vacuum and they shut down the reactor shortly after 1 p.m., said NRC spokesman Neil Sheehan.
“There were no complications during the shut down,” Sheehan said.
The plant’s resident NRC inspectors responded to the facility’s control room when they learned of the event, he said.
They did not identify any safety concerns or performance issues, Sheehan said, adding they will follow the company’s efforts to troubleshoot the problem.
Plant technicians are investigating the cause of the loss of vacuum, said Entergy spokesman Rob Williams.
Once they find the cause, workers will make any necessary repairs and the plant will come back online, Williams said.
In May last year, Pilgrim experienced an automatic shutdown the NRC determined was from human error. The NRC gave the plant a “white” finding related to the May 10 unplanned shutdown, known as a scram.
In November, the plant shut down while at reduced power because a valve was inoperable. The plant shut down again in December so plant workers could repair a leaking safety relief valve that helps control steam pressure at the facility.
Despite these problems, overall the 40-year-old plant operated safely in 2011, according to the NRC.
Opponents, however, continue to argue the plant should shut down for good because of safety and environmental concerns related to its operation.
Pilgrim’s license to operate expires June 8. Entergy has asked the NRC for a 20-year extension of the license. A decision on that request is pending.