The U.S. Nuclear Regulatory Commission has cited Mitsubishi Heavy Industries… (Mark Boster / Los Angeles…)
SACRAMENTO -- Federal regulators have issued proposed safety violation citations to Southern California Edison Co. and its contractor for alleged design flaws in steam generators at the San Onofre nuclear power plant.
The Nuclear Regulatory Commission on Monday released the results of an inspection into the failures that led to Edison's decision in June to shutter two units at the electricity generating station near San Clemente.
In January of 2012, steam tubes in one of the units began to leak and the complex was shut down.
The commission preliminarily determined that inadequate computer modeling done by the contractor, Mitsubishi Heavy Industries, led to a deficient design of the steam generators and created a safety problem of "low to moderate" significance.
The commission is not seeking any financial penalties from either Edison or Mitsubishi.
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Edison has 10 days to notify the commission whether it will accept the findings, while Mitsubishi has 30 days to respond in writing. Edison has not determined how it might respond, said spokeswoman Maureen Brown.
Edison Vice President Pete Dietrich said the company wasn't surprised to receive the proposed citation because the utility had ultimate oversight responsibility. However, he stressed that Mitsubishi came up with the flawed design and failed to properly verify that the system was adequately built.
"SCE is responsible for the safe operation of San Onofre and will continue to make safety our top priority as the plant is decommissioned," Dietrich said. "Mitsubishi Heavy Industries is accountable for its failure to provide properly functioning steam generators."
The flaw noted by the commission "had no impact" on the "unprecedented" vibration that caused the steam generator leak, Mitsubishi said in a statement.
In July, Edison announced that it was initiating legal action against Mitsubishi to recover damages that the company said could reach into the hundreds of millions of dollars.
When it was operating at full power, San Onofre made enough electricity to run more than 1.4 million homes in Southern California.
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