Baltimore Gas and Electric Co.'s Calvert Cliffs nuclear power plant will remain partially shut down at least through tonight, as investigators determine what caused the partial loss of electrical power that runs the plant's safety equipment.
BGE's Calvert Cliffs Unit Two nuclear reactor automatically shut down Tuesday at 5:08 p.m., after four cooling pumps failed to work because of the power loss. As required by the Nuclear Regulatory Commission, BGE declared the shutdown an "unusual event" less than an hour later and notified the NRC.
"All backup and emergency systems worked as they were supposed to," said Victor Dricks, an NRC spokesman in Philadelphia, the region that oversees Calvert Cliffs. "They're still in what we call a hot shutdown, where the plant remains pressurized but there are no atoms being split."
As a result of the automatic shutdown and subsequent stabilization of Unit Two, the "unusual event" declaration was called off at 8:15 p.m.
Mr. Dricks said the agency has no plans to send inspectors to the 845-megawatt plant, and area residents are in no danger. The NRC maintains on-site, resident inspectors at Calvert Cliffs. While outages at Calvert Cliffs are rare, they draw attention in the wake of forced shutdowns between 1989 and 1991, in which BGE incurred costs of $458 million. It is expected that the utility could be liable for as much as $194 million of that amount, based on a recommendation by the state in a case before the Maryland Public Service Commission, the state agency that regulates utility concerns.
BGE engineers are still investigating the exact cause of the Tuesday shutdown. The problem occurred after the company had been "trouble shooting" on a different portion of the 500,000-volt electric line that supplies power to the Lusby plant's safety equipment, causing a circuit breaker to disconnect.
"We want to know exactly what happened and why before we restart the unit," said Karl R. Neddenien, a BGE spokesman.
BGE expected to have a full review completed late last night.
Joe Gilliland, an NRC spokesman at the federal regulatory body's headquarters in Rockville, said the power interruption could have been caused by an equipment malfunction, human error or even lightning.
The last automatic shutdown of one of Calvert Cliffs' two reactors occurred in January 1995, Mr. Neddenien said.
The shutdown had no effect on Calvert Cliffs Unit One, which continues to operate at full capacity. BGE has owned and operated the Calvert Cliffs plant, which provides nearly 40 percent of the utility's power, since 1975. Last year, Calvert Cliffs set a production record by generating 12.9 million megawatt-hours of electricity.