A sensor detected a steam generator tube leak Tuesday in one of the two units of the San Onofre Nuclear Generating Plant in San Diego County Tuesday, prompting the shutdown of the nuclear reactor, the Los Angeles Times reported.
Because the building containing the tube is not airtight, it is possible radioactivity escaped into the environment, KNBC-TV, Los Angeles, reported.
"It would have been very, very small, low level, which would not pose a danger to anyone," Nuclear Regulatory Commission spokesman Victor Dricks said.
An evacuation was not required, and none of the radiation detectors located throughout the facility reported any measurable amount of radioactivity, Southern California Edison spokesman Gil Alexander said.
Southern California Edison operates the facility, which is in the northwestern corner of San Diego County, near San Clemente.
After the problem is resolved, it will take several days to restart the reactor, KNBC-TV reported.