May 3, 2012 | 6:40 pm

A Southern California Edison executive said Thursday that the company is hoping to have the shuttered San Onofre nuclear plant back up and running in June, but even then the plant will have to run at a reduced capacity for the immediate future — and perhaps forever.

The reduced operation is meant to compensate for manufacturing defects that led to the plant’s closure three months ago.

Stephen Pickett, the company’s executive vice president of external relations, said Edison is preparing to propose a plan to the U.S. Nuclear Regulatory Commission that would have the plant’s reactor Unit 2 fired back up in early to mid-June and Unit 3 one to three weeks later.

The NRC will need to sign off on the plan before the plant can restart.

The plant has been closed since Jan. 31, when a steam generator tube in the plant’s reactor Unit 3 sprung a leak, releasing a small amount of radioactive steam. Since then, more than 500 of the plant’s 39,000 tubes have been taken out of service due to excessive wear.

Pickett characterized the problem as a “manufacturing defect” but said Edison has yet to determine whether the issue was caused by design problems or the way the equipment was put together.

San Onofre’s four steam generators were replaced within the last two years or so at a cost of $671 million, a figure to be recovered from ratepayers.

Pickett said the flow of steam through the tubes is causing some longer tubes to vibrate and rub against each other in Unit 3. Initially, officials said the wear in Unit 2 was of a less unusual type, with tubes rubbing against support structures. But later testing found two tubes at Unit 2 with the same type of wear.

He said the vibration appears to be caused by the level of steam flow through the tubes, which is causing certain longer tubes to vibrate and rub against each other.

In the near term, operating the plant at less than full capacity is the only way to make sure that the issues do not resurface, Pickett said.
“Whether we can do something in the longer term to operate at greater power levels, in terms of a mechanical fix, has yet to be determined,” he said.

The revelation came a day after Edison International’s quarterly earnings report, which estimated that the company’s cost for inspections and repairs — primarily plugging the degraded tubes to take them out of service — will be between $55 million and $65 million.

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