Calvert Cliffs Reactor Shuts Down

Thursday, May 23, 2013 @ 06:05 PM gHale

Plant operators powered down the Unit 2 reactor at Calvert Cliffs nuclear power plant in southern Maryland Tuesday after a pump that feeds water to a steam generator shut down because of high vibrations.

This is the second unplanned shutdown in the past two weeks.

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The cause of the pump’s vibrations appears to be a failed mechanical coupling between the pump’s motor and the pump, said Neil Sheehan, spokesman for the Nuclear Regulatory Commission (NRC).

Sheehan and Kory Raftery, spokesman for Constellation Energy Nuclear Group, said the manual shutdown went smoothly and posed no safety risks for plant workers or the public. Raftery said the reactor was in “stable condition.”

Both spokesmen said Tuesday’s shutdown appears unrelated to the unplanned “scram” of the same reactor on May 8. In the earlier case, according to accounts from Constellation and the NRC, an electrical malfunction caused some valves to close that feed steam to the turbine. The turbine then shut down, prompting the reactor itself to shut down automatically to prevent the buildup of steam pressure in the cooling system.

The reactor was out of service for five days while workers fixed the valves and then tested them. Plant personnel also installed electrical monitors to check for further problems, Raftery said.

Unit 2 will remain shut down until an investigation of the latest malfunction wraps up, plant workers make repairs and they fully test the system, Raftery said. Unit 1, the other reactor at the plant in Lusby, MD, is operating at 100 percent power.

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