A small amount of radioactive gas escaped from a steam generator , the NRC says . Comment: Operators shut down the No . 3 reactor at California 's San Onofre plant as a result .
A small amount of radioactive gas escaped from a steam generator , the NRC says . The leak does not pose any threat to human health , an NRC spokesman says . Operators shut down the No . 3 reactor at California 's San Onofre plant as a result .