One reactor at Constellation Energy's Calvert Cliffs Nuclear Power Plant automatically shut down Wednesday afternoon after a temporary problem distributing electricity to the grid, a company spokesman said.
Calvert Cliffs I remains shut down as officials troubleshoot and investigate why that problem occurred at 1:51 p.m., said the spokesman, Dave Fitz.
"Plant staff took appropriate action," he said. "The safety of Calvert Cliffs was never threatened from this activity."
Staff reported the shutdown to the NRC within two hours, Fitz said. The plant has two Nuclear Regulatory Commission inspectors who work at Calvert Cliffs full time.
The second reactor at Calvert Cliffs is operating without problems Thursday, although at 96 percent power due to regularly scheduled maintenance, Fitz said.
The NRC must investigate further if the plant has more than three unplanned shutdowns in 7,000 hours of operation, according to commission spokesman Neil Sheehan.
This is the second unexpected shutdown for Calvert Cliffs this year. In February, melting snow on a leaky roof triggered loss of power to one reactor, prompting Calvert Cliffs II to shut down as well. A NRC team conducted a special inspection after that incident that concluded on April 30; a report on the review will be issued within 45 days, Sheehan said.