Edison Seeks to Restart San Onofre Unit, Run Below Capacity

Edison International (EIX), owner of California’s second-largest utility, has proposed restarting Unit 2 at its San Onofre nuclear power plant in California and running it at 70 percent of capacity to avoid shaking damaged pipes.

Five months after the restart, Edison will shut Unit 2 to inspect the steam generator for tube wear, the Rosemead, California-based company said in a statement today. Unit 3, which leaked radioactive water from a steam generator, will remain shut for further study. Edison didn’t propose a restart date. Both units have been shut since January.

The U.S. Nuclear Regulatory Commission will review Edison’s analysis of the cause of the pipe damage that shuttered both units in January and its restart plans before allowing the reactor to return to service. The agency will take a “number of months” for inspections and analysis before deciding on a restart of Unit 2, Chairman Allison Macfarlane said in a statement today.

Edison’s Unit 2 would produce 800 megawatts at reduced power, and it’s too early to know if the reactor would be online by next summer, Pete Dietrich, chief nuclear officer at Southern California Edison, said today during a call with reporters.

Costly Shutdown

The 2,200-megawatt San Onofre plant was closed after inspectors found unusual wear on tubes that carry radioactive water at its Unit 2 and Unit 3 reactors. The shutdown has cost Edison’s Southern California Edison utility $165 million in inspection, repair and replacement power costs as of June 30, the company said in a July 31 presentation to investors.

State regulators may open an investigation into whether the reactors should be removed from Edison’s utility rates as soon as next month.

In July, NRC inspectors said faulty computer modeling and manufacturing issues contributed to the unusual tube wear, which is more extensive at Unit 3. Mitsubishi Heavy Industries Ltd. (7011) built the steam generators, installed in Unit 2 in January 2010 and in Unit 3 in January 2011, according to the NRC.

Steam generators are massive radiator-like assemblies that transfer heat from the reactor to power-generating turbines.

David Freeman, an adviser to Friends of the Earth, an environmental group, said in an e-mail statement that operating the reactor at reduced power without fixing or replacing the generators “is like driving a car with worn-out breaks but promising to keep it under 50 miles an hour.”

Unloading Fuel

Independent analysis and more than 170,000 inspections have led Edison to conclude that it can operate Unit 2 at reduced power safely, Dietrich said today.

“This is not an experiment,” he said. “We have taken this seriously.”

Edison is unloading fuel from Unit 3, where leaks and tube damage were first discovered, and said in August it was laying off 730 employees, one-third of the plant’s workforce.

The company is considering replacing or repairing Unit 3, where loose tube supports have contributed to more damage than Unit 2, Dietrich said.

The nuclear plant is located about 60 miles (97 kilometers) south of Los Angeles and can produce power for 1.4 million homes, according to Edison’s website.

The shares rose 1.5 percent to $47.28 at 12:46 p.m. in New York.

To contact the reporters on this story: Mark Chediak in San Francisco at mchediak@bloomberg.net; Jim Polson in New York at jpolson@bloomberg.net

To contact the editor responsible for this story: Susan Warren at susanwarren@bloomberg.net

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