The utility that runs California's San Onofre nuclear plant misled federal regulators about untested equipment and design changes that could result in the failure of tubing that carries radioactive water, according to a new report commissioned by an environmental group.

The analysis, conducted by nuclear consulting firm Fairewinds Associates and commissioned by Friends of the Earth, warns that the alloy tubing in the plant's steam generators requires more study before the San Onofre reactors are restarted.

In 2009 and 2010, the plant received a multimillion-dollar makeover, including the installation of two nuclear reactors. One of the reactors, Unit 3, was shut down as a precaution in January after a leak sprung in a tube carrying radioactive water. Its twin, Unit 2, was shut down for maintenance and refueling, but it was found to have extensive wear on its tubing, as well.

A team of federal investigators has been trying to determine what has caused the heavy wear. No date has been set to restart the reactors.

According to the report, the alloy was changed, bracing was redesigned and more tubes were added. The extensive changes were never disclosed to the government, allowing Southern California Edison, the utility that operates the plant, to go on with the revisions without Nuclear Regulatory Commission oversight.

The report says the plant, which is about 45 miles north of San Diego, "has experienced rapid degradation of their steam generator tubes" since the alterations. Such rapid wear can raise the potential for a radioactive accident.

A spokeswoman for Southern California Edison said the company would not comment until the report had been reviewed (Michael Blood, Associated Press, March 27). -- JE