"Faulty computer modeling caused the equipment problems that are expected to keep the San Onofre nuclear plant dark through the summer, federal regulators said Monday."
"Officials from the U.S. Nuclear Regulatory Commission gave their first public account of the initial findings of their investigation into the plant's problems at a meeting in San Juan Capistrano.
What they did not give was any indication of how long the plant is likely to remain out of service, saying there are still questions plant operator Southern California Edison needs to answer and more inspections the NRC must do.
The plant has been out of service since Jan. 31, when operators discovered a small leak in one of the thousands of steam generator tubes that carry hot, radioactive water used to create steam to turn turbines that generate electricity.
That led to the discovery that other tubes were rubbing against support structures and adjacent tubes, and wearing out more quickly than expected. Eight tubes failed pressure testing, which NRC officials said Monday is the first time in the nuclear industry that more than one tube at a plant has failed."