San Onofre nuclear plant’s serious safety problems

Made in Japan? Fukushima Crisis Is Nuclear, Not Cultural TruthOut14 July 2012  By Gregg Levine, Capitoilette | News Analysis “……..Back at San Onofre, US regulators disclosed Thursday that the damage to the metal tubes that circulate radioactive water between the reactor and the steam turbines (in other words, part of the system that takes heat away from the core) was far more extensive than had previously been disclosed by plant operators:

[Each of San Onofre’s steam generators has] 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.

“The new data reveal that there are thousands of damaged tubes in both Units 2 and 3, raising serious questions whether either unit should ever be restarted,” said Daniel Hirsch, a lecturer on nuclear policy at the University of California, Santa Cruz, who is a critic of the industry. “The problem is vastly larger than has been disclosed to date.”

And if anything, the Nuclear Regulatory Commission is underplaying the problem. A report from Fairewinds Associates, also released this week, unfavorably compared San Onofre’s situation with similar problems at other facilities:

[SONGS] has plugged 3.7 times as many steam generator tubes than the combined total of the entire number of plugged replacement steam generator tubes at all the other nuclear power plants in the US.

The report also explains that eight of the tubes failed a “pressure test” at San Onofre, while the same test at other facilities had never triggered any more than one tube breach. Fairewinds goes on to note that both units at San Onofre are equally precarious, and that neither can be restarted with any real promise of safe operation….. http://truth-out.org/news/item/10333-made-in-japan-fukushima-crisis-is-nuclear-not-cultural

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