May 23 - Knight Ridder/Tribune Business News - Bruce Henderson The Charlotte Observer, N.C.

A team of federal investigators will visit the Catawba nuclear plant on Lake Wylie today to learn what led to the emergency shutdown this weekend of both of the plant's reactors.

Duke Energy declared an "unusual event," the lowest of four emergency stages, Saturday afternoon when the plant lost its off-site power source.

The reactors automatically shut down with the power loss, the first time both have "tripped" in the plant's 20-year operating history. Diesel generators kicked on to supply backup power.

"The plant responded as it should have," Duke spokeswoman Rita Sipe said Monday. The Nuclear Regulatory Commission said the public was not in danger.

No leaks were detected from the reactors' steam generators, through which radioactive water circulates. Off-site power was restored about six hours later, on Saturday night.

Duke said the problem occurred in the plant's switchyard, which sends electricity generated at Catawba toward customers and also brings electricity into the plant.

Ken Clark, an NRC spokesman in Atlanta, said an electrical fault in the switchyard opened a circuit breaker. What's unclear, he said, is why 12 other circuit breakers also opened, severing the connection to offsite power.

"This is a type of event that we would not expect to occur," Clark said.

 

Bruce Henderson: (704) 358-5051.