California nuclear plant shut indefinitely amid hunt to find cause of problems [View all]
A large Southern California nuclear plant is out of commission indefinitely, and will remain so until there is an understanding of what caused problems at two of its generators and an effective plan to address the issues, the nation's top nuclear regulator said Friday.
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.
Each of the 65-foot-tall, 640-ton generators -- built by Japan's Mitsubishi Heavy Industries -- are packed with thousands of narrow tubes that carry hot, pressurized water from the reactors. The heat produces steam in a separate loop that drives the plant's turbines and generators.
Located near San Clemente, the San Onofre nuclear plant's twin reactors are "Southern California's largest and most reliable sources of electricity," according to Southern California Edison's website. When operational, the facility -- which is owned by that utility, San Diego Gas and Electric, and the city of Riverside -- supplies power for 1.4 million households at any given time.