A malfunction at the Calvert Cliffs nuclear power plant caused an automatic shutdown of one of the two reactors there Thursday morning, the latest in a series of issues at the Southern Maryland facility.
Chicago-based Exelon Corp., which operates Calvert Cliffs, said the malfunction happened during electrical breaker testing. The Unit 1 reactor shut down as a result at about 10:15 a.m.
"All safety systems responded as designed and the plant came off-line as expected," Exelon said in a statement.
Calvert Cliffs' Unit 2 reactor is still at full power, Exelon said. It called the condition of the plant "safe and stable" and said it does not expect that electrical service to customers would be affected.
The incident was one of several shutdowns in the last few years at the plant, built in the 1970s. The most notable among them was both reactors going offline in January after an electrical malfunction — knocking out a major source of power as demand spiked in the bitter cold.
The Nuclear Regulatory Commission sent a team to conduct a special inspection after that event but concluded in March that overall, the plant "took appropriate actions."