NRC Sends More Inspectors to Calvert Cliffs Nuclear Plant

By Guy Leonard, St. Mary's County Times

HOLLYWOOD, Md. (April 16, 2015)—After another dual plant shutdown at Calvert Cliffs Nuclear Power Plant in Lusby last week the Nuclear Regulatory Commission (NRC) is sending inspectors to delve deeper into the causes of the latest mishap.

The shutdown was listed as an unplanned one, according to the NRC. When a transmission line from the power grid feeding electricity into the plant failed, it caused the shutdown of the two fission reactors.

After the shutdown, reactor No. 2’s backup electrical generator activated to provide power but “tripped” just 11 seconds later, the NRC stated.

“This same diesel generator failed to start in 2010 after a loss of off-site power,” an NRC statement reads. “In addition, one of three saltwater pumps on Unit No. 2 failed to automatically restart when power switched to the emergency diesel generators. Per procedure, operators manually started the pump, which provides cooling water to certain plant equipment.”

This shutdown is the latest in a string of shutdowns caused by various equipment at the facility, which has drawn criticism from nuclear energy watchdog groups.

The Union of Concerned Scientists was critical of the handling of the shutdown of reactors No. 1 and No. 2 by Exelon Corporation on two occassions last year and differed with the finding of the Nuclear Regulatory Commission that the plant personnel could not have prevented it.

Those two incidents, which resulted from snow being blown into critical electrical systems, were part of a group of four incidents that have taken place since 2010.

“Twice within the past five years, precipitation leaked into the Calvert Cliffs nuclear plant and shorted out electrical power supplies, causing once reactor to automatically shut down and components to malfunction that should have protected the second reactor from automatically shutting down,” the report released in March said. “Precipitation occurs all across the United States and its dozens of nuclear power plants, but none — except Calvert Cliffs — have experienced multiple reactor shutdowns due to similar intrusions of moisture.

“In other words, other plant owners have successfully prevented even on intrusion event while Calvert Cliffs has been uable to prevent repeated events.”

Exelon, the company which owns the plant, said that the shutdown caused last year by the driving snow was not just simple precipitation and the NRC had been satisfied by their response at that time.

The inspection team arrived at the Calvert Cliffs site Monday to begin their work.

“While there was no impact on public health and safety, the issues with the emergency diesel generator and the saltwater pump warrant a closer look,” said Dan Dorman, NRC Region I Administrator.