Future of damaged Calif. nuke plant coming clearer

[October 04, 2012]  LOS ANGELES (AP) -- The future of the damaged San Onofre nuclear power plant is slowly coming into focus, more than eight months after the California seaside plant was shut down following a break in a tube carrying radioactive water.

Southern California Edison executives are scheduled to announce "operational developments" Thursday, a move widely expected to be a steppingstone in a plan to restart one of the twin reactors, Unit 2.

Last month Nuclear Regulatory Commission chief Allison Macfarlane told a Senate committee that she expected Edison to submit paperwork this week that would detail repairs and how the reactor could operate safely, opening an NRC review that she said could last months.

The NRC has said there is no timetable to restart the plant.

A plan to return even one reactor to service would be a major turning point for Edison, three months after federal regulators found that a botched computer analysis eventually led to excessive wear to hundreds of steam generator tubes that carry radioactive water inside the reactors.

In a March letter, the regulators outlined a series of benchmarks Edison must reach to restart the plant, including determining the cause of vibration and friction that damaged tubes, how it would be fixed and monitored during operation.

The trouble began Jan. 31, when the Unit 3 reactor was shut down as a precaution after a tube break. Traces of radiation escaped at the time, but officials said there was no danger to workers or neighbors. Unit 2 had been taken offline earlier that month for maintenance, but investigators later found unexpected wear on scores of tubes inside both units.

Edison has been trying for months to determine how to correct the problem, while environmental activists have depicted the plant as a disaster-in-the-making. About 7.4 million Californians live within 50 miles of San Onofre, which can power 1.4 million homes.

Overall, investigators found wear from friction and vibration in 15,000 places, in varying degrees, in 3,401 tubes inside the four generators. In about 280 spots -- virtually all in the Unit 3 reactor -- more than 50 percent of the tube wall was worn away.

As far back as early May, Edison officials talked optimistically about restarting Unit 2, where tube damage has been less extensive. The prospects for its twin reactor, Unit 3, look bleaker. Company officials have left open the possibility that the heavily damaged generators in Unit 3 might be scrapped, and it's also possible the plant will never return to its full output of electricity.

The steam generators were manufactured by Japan-based Mitsubishi Heavy Industries. The design of the generators also is under congressional scrutiny.

The plant is owned by SCE, San Diego Gas & Electric and the city of Riverside. The Unit 1 reactor operated from 1968 to 1992, when it was shut down and dismantled.

[Associated Press; By MICHAEL R. BLOOD]

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