The Associated Press March 23, 2012, 10:15AM ET

Power supply at issue with Calif. plants offline

The indefinite shutdown of two nuclear reactors on the Southern California coast could prompt officials this summer to bring in electric generators on barges or restart retired power plants to make up for lost electricity, state regulators were told Thursday.

Analysts at the agency that operates California's wholesale power system outlined a series of possible steps to avoid blackouts, if the reactors at the San Onofre Nuclear Generating Station remain offline.

Investigators at the plant north of San Diego are trying to determine why hundreds of alloy tubes in massive steam generators are wearing down at an alarming rate.

The reactors are operated by Southern California Edison, and 19 percent of power used by SCE customers comes from nuclear generation.

Officials at the California Independent System Operator said at a meeting that plans are being set to keep the lights burning in Southern California, but shortages might develop with the onset of an extended heat wave, unless steps are taken to fill the gap.

Without the reactors "reliability is at risk" in the region during times of heavy energy use, a report said.

Possible steps to avert shortages could range from urging consumer conservation to restart two power plants in Huntington Beach, which were recently shut down.

There is no date to restart the twin reactors. A team of federal investigators was dispatched to the seaside site earlier this month to focus on Unit 3. While gradual tube wear is common in steam generators over time, no one knows why so many state-of-the-art tubes in relatively new equipment have degraded quickly.

There are nearly 20,000 steam generator tubes in each of the two reactors. After tests, plant operator Southern California Edison said a total of 321 tubes will be plugged and taken out of service at the two reactors, well within the margin to allow them to continue to operate.

Inside a steam generator, hot, pressurized water flowing through bundles of tubes heats a bath of non-radioactive water surrounding them. The resulting steam is used to turn turbines to make electricity.

The tubes are one of the critical barriers in the plant that keep radiation from escaping. If a tube breaks, there is the potential that radioactivity from the system that pumps water through the reactor could escape into the atmosphere. Serious leaks also can drain cooling water from a reactor.

The plant is owned by Edison, San Diego Gas & Electric and the city of Riverside. Southern California Edison serves nearly 14 million residents with electricity in Central and Southern California.


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