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Tube wear detailed at San Onofre, California nuke plant

By Tony Cadwalader | Daily Energy Dump | July 13, 2012

Costs and scrutiny continue to mount

Federal regulators have released the most detailed information to date on damage at California’s idled San Onofre nuclear power plant, according to KFI-AM in Los Angeles reporting an Associated Press story. (Via Drudge)

“Records posted Thursday show the extent of wear in 3,400 tubes that carry radioactive water in the plant’s troubled steam generators. The tube wear caused by vibration and friction was found in 15,000 places at varying degrees of erosion. The report has implications for the fate of the plant shut down since January.”

A fuller version of the story at the AP site said: ”The steam generators, which resemble massive steel fire hydrants, are one of the central pieces of equipment in a nuclear plant. At San Onofre, each one stands 65 feet high, weighs 1.3 million pounds, with 9,727 U-shaped tubes inside, each three-quarters of an inch in diameter.

“The alloy tubes represent a critical safety barrier – if one breaks, there is the potential that radioactivity could escape into the atmosphere. Also, serious leaks can drain protective cooling water from a reactor.

“Gradual wear is common in such tubing, but the rate of erosion at San Onofre startled officials since the equipment is relatively new. The generators were replaced in a $670 million overhaul and began operating in April 2010 in Unit 2 and February 2011 in Unit 3.

“Tubes have to be taken out of service if 35 percent – roughly a third – of the wall wears away, and each of the four generators at the plant is designed to operate with a maximum of 778 retired tubes.

“In one troubled generator in Unit 3, 420 tubes have been retired. The records show another 197 tubes in that generator have between 20 percent and 34 percent wear, meaning they are close to reaching the point when they would be at risk of breaking.

“More than 500 others in that generator have between 10 percent and 19 percent wear in the tube wall.”

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July 13, 2012 Posted by | Nuclear Power | , , , , | Leave a comment