10/10/02

Washington- At least one other nuclear power plant has recently found the kind of leaks and cracks that led to severe problems at Ohio's Davis-Besse nuclear plant.

The extent of leaking boric acid at the North Anna nuclear station, north of Richmond, Va., pales when compared with what happened at Davis-Besse, according to interviews and an incident report filed this week with the Nuclear Regulatory Commission. But the North Anna cracks, along with isolated cracks found at several other plants over the last year, are indicative of the serious problems and safety risks the nation faces as its nuclear power plants age, according to the Union of Concerned Scientists.

The problems suggest a need for greater vigilance by the NRC and the companies that own the power plants, says David Lochbaum, a UCS nuclear safety engineer who used to work in the industry and maintains there is "industrywide negligence."

The leaks and cracks "clearly demonstrate that the NRC is not requiring a thorough safety overhaul of aging nuclear power plants," Lochbaum said.

NRC officials agree on the need for vigilance - but not on the conclusions about agency complacency and potential disaster.

"I think the NRC has been pretty active on this topic," said Edwin Hackett, the assistant team leader of the NRC's lessons learned task force, which reported yesterday on the Davis-Besse debacle. He cited agency alerts on possible cracks and leaks since 1997.

The NRC has "pretty reasonable assurance that there's not something on the order of another Davis-Besse situation out there," Hackett said. "That's not to say there aren't cracks" in the nickel alloy nozzles that pass through reactor lids, guiding the rods that control the nuclear reaction.

It is widely known that the nozzles and the welds that attach them to the lids "are susceptible to stress corrosion cracking, and they do crack and will crack over time," Hackett said. "It's a question of what happens with the cracks. And if plants are doing reasonable inspections," they will discover the cracks, "and you would take steps to fix it before you got into a problem like Davis-Besse."

The question is, what is a reasonable inspection?

Dominion Energy, the company that owns North Anna, conducted visual inspections last year and found no cracks. But in recent weeks, when Dominion used ultrasonic and liquid-penetrant testing to check the nozzles during a routine refueling - a procedure requested, but not required, by the NRC as a result of Davis-Besse - it discovered widespread cracking.

Of 59 nozzles in the North Anna unit, 49 had cracks, according to the UCS. Preliminary tests showed that none of them appeared to be all the way through, but leaks were discovered in six welds where nozzles were attached to the lid, Dominion says. And boric acid was found on the reactor lid.

Dominion on Monday announced that it will replace the lid over the reactor rather than try to repair the nozzles, which are attached to the lid.

Dominion spokesman Richard Zuercher says the boric acid deposits were "very, very slight," barely enough to fill a small sugar packet.

But Lochbaum points out that other plants have found cracks since 2001: the Oconee nuclear station in South Carolina, Palisades in Michigan, Crystal River in Florida and Arkansas Nuclear One in Arkansas. Most of the cracks were minor but nonetheless in violation of NRC rules, which require a plant to shut down within six hours of discovering a crack.

Although the plants said they had not discovered the cracks before then, Lochbaum says they could employ better detection devices, like moisture detection equipment used in France.

"If the NRC doesn't enforce federal safety regulations like the six-hour rule," he said, "the price tag could include an avoidable accident."

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