The Nuclear Regulatory Commission released its full report Thursday on the faulty steam generators that have
The report refutes in changing the design of the generators in order to avoid costly inspections.
"Southern California Edison provided the NRC with all the information required under existing regulations about proposed design changes to its steam generators prior to replacing them in 2010 and 2011," according to a press release from the NRC.
Nevertheless, Friends of the Earth, an environmental group issuing critical reports about the plant's problems, continues to assert that Edison didn't file the correct paperwork.
"The bottom line is that the NRC was asleep at the wheel then and now we’ve left it up to the same people to justify their mistake," according to a released statement from Friends of the Earth.
Thursday's report offers no real surprises about the causes of the wear that ruined more than 1,300 components inside steam generators at units 2 and 3.
At that meeting, NRC officials said steam generator manufacturer Mitsubishi Heavy Industries miscalculated the velocity and pressure of steam inside the thousands of tubes in the generator, underestimating it by three to four times.
Furthermore, manufacturing mistakes caused the tubes to vibrate against support structures and against each other, exacerbating wear, the NRC states.
Plant operator Southern California Edison is working on procedures to respond to the NRC officially and is continuing repairs. The San Onofre plant is jointly owned by SCE, San Diego Gas & Electric, and the city of Riverside.
“We are committed to continuing to work with the NRC on the steam generator issues and will continue to use conservative decision making as we work on repairs and planning for the future,” said San Onofre's Senior Vice President and Chief Nuclear Officer Pete Dietrich in a statement. “The number one priority is the safety of the public and our employees.”
Tubes numbering 1,317 have been plugged or taken out of service.
Super-heated, highly pressurized radioactive steam runs through the tubes, which act together like a radiator to boil pure water to make steam that turns a turbine to make electricity.
In the meantime, SCE must seek NRC approval before restarting. The utility has not given a specific timeline for doing so.