A small amount of radioactive gas escaped from a steam generator , the NRC says . CNN 's Karan Olson and Matt Smith contributed to this report . 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 . Comment: Operators shut down the No . 3 reactor at California 's San Onofre plant as a result .