'Extremely small' radiation release at Calif. plant possible, utility says Mike Blake / Reuters The San Onofre Nuclear Generating Station sits on the shore of the Pacific Ocean in San Diego County, Calif. An "extremely small" amount of radiation could have escaped into the atmosphere from a Southern California nuclear power plant after a water leak prompted operators to shut down the reactor, a utility spokesman said Wednesday. Nuclear Regulatory Commission spokesman Victor Dricks echoed that, saying a small amount of radioactive gas "could have" escaped the San Onofre Nuclear Generating Station on the northern San Diego Coast. Southern California Edison spokesman Gil Alexander said the amount would have been "extremely small" and possibly not detectable by monitors. The company and federal regulators say the release would not have posed a safety risk for the public. A reactor at the plant was shut down Tuesday night after a possible leak was detected in one of the unit's steam generator tubes. Southern California Edison on Tuesday said in a statement that "a precautionary shutdown of Unit 3" at the electricity generating plant was under way, but that there had been no release of radiation to the atmosphere and there was no danger to employees or the public.