Nuclear activists made their final plea to the Nuclear Regulatory Commission yesterday to hold a trial-like hearing before allowing the restart of crippled reactors at the San Onofre plant on California's West Coast.

"This was our only chance to go eyeball to eyeball, our only chance," said Arnie Gundersen, a nuclear engineer with Fairewinds Associates representing Friends of the Earth.

Anti-nuclear groups are calling for the crippled San Onofre reactors, about 45 miles north of San Diego, to remain shut down despite the operator's request to restart at least one unit for a five-month period.

The reactors have been offline for about a year, since Southern California Edison discovered a leak in tubes carrying hot radioactive water in steam generators that are used to produce power. The utility later discovered the tubes were worn down by mysterious vibrations. Edison is now lobbying to restart Unit 2 but has removed fuel from Unit 3.

An NRC investigation last year found that Mitsubishi Heavy Industries, which manufactured the generators, used a faulty computer model to gauge steam and water flow, which triggered vibrations that damaged the tubes (Greenwire, June 19, 2012).

But Gundersen told an NRC petition review board yesterday that Southern California Edison's order to change the design of the generators is solely to blame, and the utility should have tried to amend its license years ago to account for the large-scale equipment changes.

Doing so would have triggered an NRC investigation and prevented such a costly mistake, Gundersen said.

Friends of the Earth is calling on the NRC to suspend the utility's license until it is amended to account for the steam generator design changes. It is not clear when the NRC will act, but the agency has said it could decide on a potential restart as early as March.

Gundersen argued that Southern California Edison's problems were foreseeable and that the generator debacle is one of the worst mistakes at a nuclear plant in the past decade.

"In the past 10 years, nobody has screwed up a piece of equipment more than the steam generators at San Onofre," he told the review board.

But Gundersen's argument was also limited by the NRC's decision not to release documents detailing the tube failures. Gundersen said the agency denied his request to gain access to the documents even though he volunteered not to share the information (Greenwire, Jan. 4).

"We're boxing in the dark," he said.

Southern California Edison rebutted Gundersen's assertions in a filing to the NRC last week and maintained that changes to the steam generators did not require a license amendment.