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Feds clear California nuclear plant over allegations of cover-up on troubled steam generators
LOS ANGELES (AP) ¯¯¯ Federal regulators Thursday concluded that the operator of the San Onofre nuclear power plant in California did not mislead the government about extensive modifications to its troubled steam generators, where damage has been found on scores of tubes that carry radioactive water.
Environmental activists had accused Southern California Edison of duping the Nuclear Regulatory Commission about a series of changes to the massive machines, including boosting the number of tubes and redesigning internal supports.
The seaside plant between San Diego and Los Angeles has been shuttered since January, after a tube break in one of the generators released traces of radiation.
An NRC report concluded that Edison "provided the NRC with all the information required under existing regulations about proposed design changes to its steam generators," according to an agency statement.
But a key issue remains under study: whether the agency needs to change the process that was used to approve the replacement generators.
Daniel Hirsch, a lecturer on nuclear policy at the University of California, Santa Cruz, who is a critic of the industry, said the agency was attempting to exonerate itself from blame for the plant's ongoing troubles.
The "NRC said they did nothing wrong," even though the faulty generators caused unprecedented tube damage and raised the risk of a serious accident, Hirsch said in a statement.
The trouble began to unfold in January, when the Unit 3 reactor was shut down as a precaution after a tube break. Traces of radiation escaped at the time, but officials said there was no danger to workers or neighbors. Unit 2 had been taken offline earlier that month for maintenance, but investigators later found unexpected wear on scores of tubes in both units.
After a three-month investigation, the NRC found a botched computer analysis resulted in design flaws that are largely to blame for unprecedented wear in tubes. Edison has been trying to determine how, or if, the problems can be fixed.
The problems have raised questions about the integrity and safety of replacement generators the company installed at the twin reactors in a multimillion-dollar makeover in 2009 and 2010.
Earlier this year, a report issued by environmental group Friends of the Earth asserted that equipment and design changes to the generators "created a large risk of tube failure at the San Onofre reactors." 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."
The tubes are one of the barriers between the radioactive and non-radioactive sides of the plant. If a tube breaks, there is the potential that radioactivity from the system that pumps water through the reactor could escape into the atmosphere.
Serious leaks also can drain cooling water from a reactor.
The steam generators were manufactured by Japan-based Mitsubishi Heavy Industries, according to company officials.
The design of the generators also is under congressional scrutiny.
The plant is owned by SCE, San Diego Gas & Electric and the city of Riverside. The Unit 1 reactor operated from 1968 to 1992, when it was shut down and dismantled.