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UPDATED: Feds Probe San Onofre After Radiation Leaks

Some parts of the heat exchangers at San Onofre Nuclear Generating Station's Unit 3 failed a pressure test, officials said Wednesday.

The timeline for restarting the San Onofre Nuclear Generating Station in the wake of unexpected wear on new components is still unclear, plant and Nuclear Regulatory officials said Thursday.

Southern California Edison won’t get the go-ahead from the feds to restart the plant until the NRC figures out what caused the component failures and unexpected wear, said NRC spokeswoman Lara Uselding.

The NRC has sent an extra team of inspectors to the plant in addition to the two on-site - NRC staffers Greg Warnick and John Reynoso who work there year-round. The team, which arrives Monday, will be led by Greg Warner out of the NRC’s Arlington, Texas, office, Uselding said.

The unplanned shutdown is costing Edison $600,000 to $1 million per day, one energy expert said. Meanwhile, local anti-nuclear groups have seized on the problem to illustrate their assertion that nuclear energy is unsafe.

Three of the 129 new heat-exchanger tubes were found to have had unexpected wear after a radioactive steam leak in January. This week, they failed a pressure test and will have to be taken out of service, Southern California Edison said in a news release.

Testing the remaining tubes will take an additional eight days, Uselding said.

During normal functioning, superheated, radioactive water runs through the tubes in question—there are tens of thousands of tubes at the plant—and transfers the heat to pure water, creating steam to turn massive turbines that generate the electricity.

One of the tubes in Unit 3 sprung a leak in late January, squirting out radioactive steam before it was isolated. If any radiation escaped into the atmosphere, it was at undetectable levels, said plant officials and some outside experts.

Though the damaged tubes are only a year or so old and were replaced as part of $674-million upgrades to the plant, Uselding said it’s not unusual for the tubes to see some wear after even their first cycle.

What is unusual is the amount of wear and the number of tubes involved at San Onofre, she said. The team of experts will be studying the design, installation, shipping and operation of the new heat exchangers to determine the exact cause of the extensive wearing and will present those findings at a future public meeting, Uselding said.

Tube Testing and Operation

Though Southern California Edison will likely have to plug a number of tubes and take them out of service, Uselding said the plant could still operate at 100 percent with up to 700 tubes, or 8 percent of the tubes taken out of service.

 “Some plants can operate with more than 30 percent of the tubes plugged,” Uselding said. “It’s a plant-specific evaluation.”

So hypothetically, the San Onofre plant could be up and running even if technicians stopped up all 129 tubes in question, Uselding said. But they won’t be allowed to fire up the reactors again until the Nuclear Regulatory Commission figures out what happened to cause all the wear and tear in the first place and Edison proves they addressed the problem, she said.

According to literature provided by Southern California Edison, tubes are inspected using three different methods and three different devices.

Inspectors start by running two types of “eddy current” tests, both of which work by shooting an electric current through the tube walls to measure the thickness.

First, inspectors thread a “bobbin probe” into each tube to measure overall wear. Then, they use a more precise “rotating probe” to more thoroughly map out the areas in the tubes that showed substantial wear.

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Jeff Steinmetz March 15, 2012 at 06:51 PM
I think SCE has left out some key information here. 1) Why only 129 of the tubes are getting tested out of 19,454 steam generator tubes in Unit 3. 2) At what pressure level did these three tubes fail? Was it 1.2 times the normal pressure level or 1.5 times? Only telling us what the test process is, tells us nothing about the true results of the test or how safe or un-safe this plant is. 3) "Our tube testing plan, in accordance with industry standards is designed to help us understand the safety issues and significance of this situation.'' If the "industry standards" are good enough then why didn't the plant find the issue before you had a radiation leak and shut down on Jan 31? 4) With a shutdown costing up to $1 million a day and SONGS shut down now for 44 days; should the public trust your "industry standards" hold the public health and safety above all other interest? 5) what about unit 2? "Unusual wear has been found in hundreds of tubes in adjoining Unit 2. "A Nuclear Regulatory Commission spokesman said several hundred tubes in Unit 2 showed wearing on the inside; two were shot, and almost 900 others had significant thinning. The components are only one to two years old. "
Jeff Steinmetz March 15, 2012 at 06:53 PM
6) If the plant new they had this issue in unit 2, then why didn't the "industry standards" dictate they need to check the tubes in Unit 3 to ensure public health & safety? 7) The NRC new about the issue in unit 2, so why didn't this sleeping watch dog insist unit 3 be shut down and this issue investigated? Instead the plant was allowed to continue operations that resulted in a radiation leak and un-planned shutdown. 8) All of this occurred within one year of the tragic events in Fukushima, so the nuclear power industry, SONGS, and the NRC all knew now is the worst possible time for a radiation leak. The entire nuclear power industry understood the events in Fukushima are a significant threat to the industry, yet they still dropped the ball? In the case SONGS, the nuclear power plant with the worst safety record in the US, could it be they don't have adequate control of the ball? 9) What is going to happen when mother nature throws this plant a curve ball in the form of large earthquake or tsunami? Keep in mind they failed to keep things under control under normal operations. The pipes failed because they wore to thin and burst under the pressure. What is going to happen when you shake the ground under the pipes and add additional stress to the already weak pipes from "significant thinning"?
Gene Stone March 15, 2012 at 10:05 PM
Why have workers told us SCE cut the testing short when they installed them 18 months ago? Does Safety first really mean Profits first? http://residentsorganizedforasafeenvironment.wordpress.com/
Patti Davis March 15, 2012 at 11:56 PM
How do you like our coast as a hazardous radioactive nuclear waste dump for 200 - 300 years? That is the plan the NRC has for San Onofre. Help Stop This Madness http://sanonofresafety.org/california-nuclear-initiative/print-petition/
CriticalThinkerInFV March 16, 2012 at 12:56 AM
Shut it down for good
Chrystal coleman March 16, 2012 at 03:46 AM
Shut it down permanently! Nuclear energy is a crime against humanity. We have all seen the effects of nuclear radiation from Chernobyl 30 years ago. I'd rather live in the dark than have my children, and the next 10 generations born with birth defects and die of cancer. You can't reverse the effects of radiation. This is ridiculous. It isn't worth the risks! Shut it down!
Diane Hennessy March 16, 2012 at 05:24 PM
"The NRC has sent an extra team of inspectors to the plant in addition to the two on-site - NRC staffers Greg Warnick and John Reynoso who work there year-round. " So why didn't the two working there year round figure this out? This is crazy making stuff.. They test this week and they burst again. Time to close shop!
Ronald Douglas Kennedy March 26, 2012 at 05:03 PM
Greetings Jeff. Great read on this present issue. Regarding Your Question 9) "What is going to happen when mother nature throws this plant a curve ball in the form of large earthquake or tsunami? Keep in mind they failed to keep things under control under normal operations." Plate tectonics study of the San Onofre and Inglewood Fault. As one large strike, need to be understood before this facility goes back on line. Also the storage polls for spent full rods need to be moved inland. Of the sea bluff .
Gene Stone March 26, 2012 at 05:25 PM
Join our Volunteer Monitoring Network at: http://residentsorganizedforasafeenvironment.wordpress.com/2012/03/22/volunteers-of-america/

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