California nuclear plant shut indefinitely amid hunt to find cause of problems

http://www.cnn.com/2012/04/06/us/california-nuclear-plant/index.html

"The power plant has been shut down since this winter, when a small amount of radioactive gas escaped from a steam generator during a water leak. At the time, federal regulators said there was no threat to public health, though they could not identify how much gas leaked or exactly why it had happened."