He said the water leak was about six-hundredths of a gallon per minute , far below the levels required to declare an `` unusual event '' -- the lowest of four NRC alert levels . A small amount of radioactive material escaped from a steam generator , the NRC says . The leak does not pose any threat to human life , an EPA spokesman said . Operators shut down the No . 3 reactor at California 's San Diego plant as a result .
A small amount of radioactive material escaped from a steam generator , the NRC says . The leak does not pose any threat to human life , an EPA spokesman said . Operators shut down the No . 3 reactor at California 's San Diego plant as a result .