A 450-megawatt reactor at the San Onofre nuclear power plant has been shut down for an indefinite period because of a faulty water pump, a Southern California Edison spokesman said Friday.
The Unit 1 reactor was shut down about two hours after officials determined at 10 p.m. Thursday that the pump was malfunctioning, said David Barron, a spokesman for the utility company.
Barron said there was no release of radiation because of the malfunction and the plant's operators were able to shut down the reactor without incident.
After the shutdown, authorities declared that an "unusual event" had taken place, the lowest alert level in the nuclear industry. An unusual-event warning must be issued each time a reactor is shut down due to equipment malfunction, Barron said.