OAK HARBOR, Ohio - Deja vu for Davis-Besse?
After six years of rock-solid performance, the Ottawa County nuclear plant faces the prospect of staying offline for another extended period because multiple control-rod drive mechanism nozzles that jut out of its reactor head - one of the plant's largest and most important parts - again are aging faster than expected.
As of late yesterday afternoon, ultrasonic tests revealed possible flaws on 13 of the 52 nozzles that had been inspected, including four with confirmed cracks. Seventeen of the reactor head's 69 nozzles had not yet been inspected.
The situation is eerily close to what happened when the nuclear plant was forced to shut down for two years in 2002. But Viktoria Mitlyng, Nuclear Regulatory Commission spokesman, said there is no evidence of acid escaping from the reactor, pooling up on the head's surface, and compromising the integrity of the structure this time.
She said only about a teaspoon of dried boron - leakage evidence - was found on welds near the base of two nozzles, a sign the problem was caught in its early stages.
Cracks occasionally are found on such nozzles, but usually on equipment that has been in service longer than six years.
Mel Holmberg, the NRC's top metallurgist in its Midwest regional office near Chicago, was dispatched to the plant to look for clues that might explain premature aging.
No danger exists to the public unless Davis-Besse is put back into operation in substandard condition, a violation of federal NRC rules. That's what happened in 2000 and possibly earlier restarts, according to a joint investigation by the NRC and the U.S. Department of Justice that resulted in a record $33.5 million in fines being assessed against the utility and sanctions being taken against two former workers, as well as an in-house investigation that resulted in numerous firings.
The 2002 event has been described by federal officials as one of the greatest cover-ups in nuclear history. It led to changes in how plants are regulated nationally.
FirstEnergy, charged multiple times by the NRC for withholding information from the government in that case, has vowed to never have a repeat of that incident. The utility said it made good on that promise by reporting the latest problem at the first sign of trouble.
Indeed, the NRC has lauded FirstEnergy for safely operating Davis-Besse since the regulator allowed the utility to put the plant back into operation six years ago this month. That restart followed a record two-year outage that included not only technical fixes, but evidence that FirstEnergy executives had improved the plant's workplace atmosphere, or safety culture, so that employees and contractors would have a greater sense of assurance they would be taken seriously if they pointed out problems.
"The plant has been operating safely, it has been operating well. The performance speaks for itself," Ms. Mitlyng said.
Davis-Besse has been idle since its biennial refueling and maintenance outage began Feb. 28. Such outages typically last four to six weeks.
Nuclear reactors are refueled once every 18 months to two years, depending on the type of uranium in their fuel. During those outages, thousands of inspections and repairs are done - many of which cannot be performed while a plant is in service.
Todd Schneider, FirstEnergy spokesman, said the latest discovery of nozzle cracks - which began starting at 9:43 p.m. Friday - came as a morale blow to the plant's 600-some employees, many of whom helped bring it back into service following its two-year outage.
"The people here, while disappointed in finding something, are gratified they found it and reported it," he said. "We didn't expect to find this issue."
Mr. Schneider said it's impossible to predict now how much of a delay will result. He said the utility should have a better idea when tests are completed Monday.
France-based AREVA, one of the world's largest nuclear parts suppliers and contractors, is dispatching repair crews, he said.
"It's going to impact the schedule," Mr. Schneider said of the repairs. "We don't know exactly yet what type of impact it will be."
The plant's reactor head came from a scuttled nuclear plant in Midland, Mich. The dome-shaped cap was built in 1975 with a type of metal alloy that has been phased out in the nuclear industry for failing to hold up as well under years of pressure as scientists in the 1960s thought it would.
Both FirstEnergy and the NRC had expected worry-free operation from the replacement head for at least 10 to 15 years after putting Davis-Besse back into service in 2004.
Davis-Besse went online in 1977. Its original head was within weeks of bursting and allowing radioactive steam to form when the plant was taken offline for refueling and maintenance in 2002, according to studies done by the NRC and the U.S. Department of Energy.
The issue isn't just the presence of cracks but also the type of them.
Officials are trying to determine if any of the nozzles have circular-shaped - also known as circumferential - cracks in them. Those are the most dangerous. They follow a 360-degree pattern and make nuclear reactors more susceptible to releasing radioactive steam, because they compromise the integrity of the nozzles so much they can pop off like champagne corks when a plant is operating.
Those types of cracks were first discovered in France in the 1980s. They were found for the first time in the United States in 2001 at the Oconee nuclear plant in South Carolina, then at Davis-Besse in 2002. FirstEnergy has had an order on file with AREVA for a new reactor head out of a more durable alloy.
They take three years to build. The utility expects to install it on the Davis-Besse reactor in 2014, Mr. Schneider said.
Contact Tom Henry at:
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Deja vu for Davis-Besse? After six years of rock-solid performance, the Ottawa County nuclear plant faces the prospect of staying offline for another extended period because multiple control-rod drive mechanism nozzles that jut out of its reactor head - one of the plant's largest and most important parts - again are aging faster than expected.