Feds: San Onofre Will Remain Shut

Wednesday, March 28, 2012 @ 02:03 PM gHale

As much as the potential power crunch this summer holds for Southern California, the troubled San Onofre nuclear plant will remain shut down until federal regulators can determine why tubes carrying radioactive water in the plant’s massive generators are rapidly decaying.

That news formalized an agreement with operator Southern California Edison (SCE) on the same day a report commissioned by an environmental group said the utility misled the Nuclear Regulatory Commission (NRC) about design changes that are the likely culprit in excessive tube wear.

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A four-page letter from NRC Regional Administrator Elmo E. Collins laid out a series of steps Edison must take before restarting the seaside reactors located 45 miles north of San Diego.

Elmo wrote the plant’s operator must resolve and fix the problems in the generators and “until we are satisfied that has been done, the plant will not be permitted to restart.”

The plant’s four steam generators each contain nearly 10,000 alloy tubes that carry hot, pressurized water from the reactors. The Unit 3 reactor shut down as a precaution in January after a tube break, and extensive wear was also on similar tubing in its twin, Unit 2, which shut down for maintenance.

Authorities in California have been scrambling to find additional power in case the reactors remain off-line through summer, when energy use typically peaks. That could include restarting retired plants in Huntington Beach in northern Orange County.

The company found the cause of the tube wear is coming from vibration and friction with adjacent tubes and bracing, however investigators don’t know why that’s happening.

The company “has been committed from the beginning to not returning Unit 2 or Unit 3 to service until we are satisfied it is safe to do so,” said SCE Spokeswoman Jennifer Manfre.

The problems raised questions about the integrity and safety of replacement generators the company installed at the two reactors in a multimillion-dollar makeover in 2009 and 2010. Traces of radiation escaped during the January leak, but officials said there was no danger to workers or neighbors.

The report by nuclear consultants Fairewinds Associates warned there needs to be a more detailed study on the alloy tubing in the generators before anyone restarts the reactors.

The study was for nuclear watchdog Friends of the Earth and authored by engineer Arnie Gundersen, a former nuclear industry executive who was a licensed reactor operator.

A series of equipment and design changes to the generators “created a large risk of tube failure at the San Onofre reactors,” the report found, citing a review of publicly available records. It said the rapid tube wear can raise the potential for an accident that could release radioactivity.

Among the modifications, the report said the tube alloy changed, they redesigned the bracing and added more tubes. It said the company never disclosed that such extensive changes were made, instead describing it as an exchange of similar equipment that allowed SCE “to avoid the requisite NRC oversight of a steam generator replacement.”

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