One of the San Onofre nuclear power plant's reactors
automatically shut down Sunday after a problem developed with a
circulating water system. The reactor, Unit 2, which generates
about 1,100 megawatts of electricity, was still not operating
yesterday morning. The other reactor, Unit 3, was operating at
full power. Southern California Edison, which operates the
plant, reported the incident to the Nuclear Regulatory
Commission as a “nonemergency.” Reactors are programmed to shut
down automatically in some instances. In this case, water
circulating through the plant slowed, causing a rise in water
temperature. That triggered an automatic reactor shutdown,
according to the report filed with the NRC. A plant spokesman
couldn't be reached for comment yesterday.