Davis-Besse scrutinized

3/19/2010

OAK HARBOR, Ohio - Federal regulators want to know what, if any, lessons from Davis-Besse's latest relapse can be applied to the nation's 103 other nuclear plants, according to one of the key members of the special inspection team dispatched to the site by the U.S. Nuclear Regulatory Commission.

Jay Collins, a senior materials engineer at the NRC's headquarters in suburban Washington, said it will take some time before he and others on the inspection team discern what might be applicable to the rest of the industry and what is potentially unique to Davis-Besse, one of only seven plants with a Babcox & Wilcox design.

Since at least June of 2002, during a meeting of the NRC's Advisory Committee on Reactor Safeguards, the agency has known that the nation's Babcox & Wilcox plants typically operate hotter than others.

Davis-Besse, with an operating temperature of 605 degrees, was the nation's hottest in 2002. It typically operated 20 degrees warmer than the industry average of 585 degrees.

Mr. Collins said it was last known to be operating at about 600 degrees.

But he said the public should not jump to any conclusions.

Other factors could be contributing to the premature degradation of the control-rod drive mechanism nozzles on the reactor head that Davis-Besse put into service in 2004, he said.

Davis-Besse began operating in 1977. Its original head nearly burst in 2002 after FirstEnergy Corp. had allowed acid from the reactor to build up on it over six years or more, the NRC has said.

Its replacement head came from the Midland 2 nuclear plant in Midland, Mich., one that Consumers Power, the predecessor of Consumers Energy, stopped building in 1985.

That head is made of an inferior metal alloy, called Alloy 600, that is being phased out in the nuclear industry.

FirstEnergy and the NRC thought the utility would have a new head made of a superior metal alloy, called Alloy 690, on the Davis-Besse reactor before the one from Midland developed cracks. The new head is not expected to be ready until 2014.

Initial tests show potential flaws in 14 of the 69 nozzles jutting out of the current reactor head.

At least four have confirmed cracks, two with through-wall leakage, according to a utility report the NRC has posted online.

"It does raise a concern with the number of indications that they've received so far," Mr. Collins said.

He said the NRC has been in contact with the California-based Electric Power Research Institute, an industry research arm.

"We need to understand why this happened," Mr. Collins said of Davis-Besse's latest setback.

FirstEnergy is responsible for compiling a root-cause report, which will be subject to NRC auditing.

Contact Tom Henry at:

thenry@theblade.com

or 419-724-6079.