California: San Onofre nuke plant safety battery inoperable 4 years

Federal regulators are ramping up inspections at the San Onofre nuclear plant after it was discovered a battery used to supply power to safety systems didn't work for four years.

Nuclear Regulatory Commission regional administrator Elmo Collins said in a statement Monday that the problem stemmed from poor maintenance and the lapse is troubling because the condition persisted for so long.

Other emergency batteries were available to supply power to plant safety systems, but the NRC said the loss of even one emergency battery reduced the plant's safety margins. It was inoperable from 2004 to 2008.

San Onofre, on the coast between Los Angeles and San Diego, is operated by Rosemead-based Southern California Edison. The utility said in a statement that it accepted the outcome of the NRC's special inspection and will focus on preventing a recurrence.

"We agree with the NRC regarding the rigor needed in problem identification and resolution. To that end, we have made significant leadership and organizational changes at San Onofre to ensure that plant performance keeps pace with continuously rising nuclear industry standards," the statement said.

The commission said the San Onofre Nuclear Generating Station will receive additional oversight because of the "white" inspection finding. The problem was discovered on March 25. NRC color-coded safety inspection categories range from green to white, yellow and red. White is a low to moderate safety significance finding.

NRC inspectors found loose electrical connections to the battery were caused by inadequate maintenance. The regulatory commission also noted seven findings determined to be of low safety significance.

The NRC report said the San Onofre plant's "ability to effectively evaluate problems has been, and continues to be, a concern to the NRC." The commission plans additional oversight at the San Onofre plant "until sustained improvements are recognized."

The San Onofre plant has troubled the NRC for some time. In September, Edison executives and NRC officials met in San Clemente to discuss safety lapses at the northern San Diego County plant.

The commission disclosed in January that Edison fired or disciplined seven employees over the last two years for safety and security violations, including one worker who skipped hourly rounds for five years and falsified hourly logs.

Edison then appointed a site manager who replaced a half-dozen plant managers and began a new accountability training.