San Onofre workers unable to find leak at Unit 3 – Additional Unit 2 tests possible

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An undisclosed number of steam generator tubes will be taken out of service at the San Onofre Nuclear Generating Station.  Workers have begun blocking “a number of tubes” that help remove heat from San Onofre Nuclear Generating Station’s Unit 2 reactor because the tubes have experienced some unexpected wear, a plant spokesman said this week.

Edison spokesman Gil Alexander declined to say exactly how many tubes will be taken out of service and added that Edison will not share overall wear data with the public until “all inspections are completed and all data is analyzed.”

However, it looks like the damage at Unit 3 might be more severe than SCE has made known.  Alexander said, workers continue to look for the leak in Unit 3 and, based on the results of that testing, “additional Unit 2 testing might occur.”

One of the replaced San Onofre Steam Generators

No restart date set after strange sequence of events

Both reactors at SCE’s 2,150-megawatt San Onofre station are currently shut to address problems with the steam generators and no return date has been set for either reactor, and Edison has set no firm date on when the plant’s two reactors will be returned to service.

San Onofre shut Unit 3 January 31 in response to indications of a steam generator tube leak and a small release of radioactive gas near the leak.

The next day, the Nuclear Regulatory Commission issued a statement saying an unrelated inspection had detected premature wear on some of the tubes in the Unit 2 reactor, but did not comment on when the wear had been found, and if it had been reported prior to the leak at Unit 3.

The final number of tubes to be plugged and taken out of service has not been determined. Inspection of the steam generator tubes in Unit 3 continues, SCE said.

“Details regarding tube wear will not be available until all inspections are completed and all data is analyzed,” the company said.



All 19,454 steam-generator tubes in Unit 2 have been checked, 9,727 in each steam generator, Alexander said.

The same number will be checked in Unit 3

Only 7 percent of generator tubes can be taken out of service before performance is affected appreciably.



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