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The company said in a statement it will provide additional evaluations next month to demonstrate Unit 2 can run at 100 percent power, even though its restart plan, based on 70 percent power, will remain unchanged.

The NRC has not ruled on that issue.

Daniel Hirsch, a lecturer on nuclear policy at the University of California, Santa Cruz, and a critic of the nuclear power industry, said the response “raises serious questions about the credibility of Edison.”

If company officials are preparing an analysis to run at full power “why have they said for months they need to restrict power to 70 percent?” Hirsch asked.

The problems at San Onofre center on steam generators that were installed during a $670 million overhaul in 2009 and 2010. After the plant was shut down, tests found some generator tubes were so badly eroded that they could fail and possibly release radiation, a stunning finding inside the nearly new equipment.

The ability of San Onofre to run safely at lower power _ and whether that limit would require an amendment to its operating license _ came up in December at a hearing of the Atomic Safety and Licensing Board, an arm of the NRC.

Administrative Judge Gary Arnold asked Edison attorney Steve Frantz if he was confident that the plant could operate at 99 percent power with its ailing generators.

“I do not say that,” Franz responded. He argued that running at 70 percent power would fall within San Onofre’s license and operating rules.

The generators, which resemble massive steel fire hydrants, control heat in the reactors and operate something like a car radiator. At San Onofre, each one stands 65 feet high, weighs 1.3 million pounds and has with 9,727 U-shaped tubes inside, each 0.75 inch in diameter. Hundreds of the tubes have been taken out of service because of damage or as a preventative step.

Craver also disclosed that Edison and the Japan-based company that built the generators, Mitsubishi Heavy Industries, are squabbling over the amount of money that could be recovered under warranty.


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