The preliminary report found it to be true and the second report confirmed it: A fire at an idled Nebraska nuclear plant last June presented a serious safety threat.
A final determination found the small fire at the Fort Calhoun plant 19 miles north of Omaha, NE, was of “high safety significance,” the Nuclear Regulatory Commission (NRC) said. The finding mirrored the commission’s preliminary conclusion released March 12.
“This finding has high safety significance because it affected multiple safety systems and consequently warrants actions to prevent recurrence,” said the NRC’s regional administrator, Elmo Collins.
The utility “knew early on that this was a serious issue and we knew we were going to get a serious finding on that. That’s why we did not contest it,” said Omaha Public Power District (OPPD) spokesman Jeff Hanson.
They replaced the faulty equipment and they have tested similar gear, he said.
Such a serious finding typically means additional oversight for a nuclear plant, but Fort Calhoun already is under the NRC’s strictest oversight level because of a prolonged shutdown that began last spring and several other reported problems, including the failure of a key electrical part during a test and flood planning deficiencies, both found in 2010.
At the time of the fire, which started in an ill-fitting electrical breaker, the plant was offline. The electrical system running the pumps that cool spent fuel in a pool of water ended up disrupted. The pumps are a key piece of safety equipment because if pumping systems were to fail for several days and not fixed, cooling water could boil away and eventually allow radioactive releases.
The NRC said pool temperatures never exceeded safe levels and no radioactivity released.
The fire raised major concern because it could have happened any time and because workers didn’t fully investigate an unusual smell in the area three days earlier, which could have led them to discover the problem and prevent the fire, the NRC said.
Fort Calhoun initially shut down for refueling maintenance last spring, but major flooding along the Missouri River forced it to remain closed.
OPPD said it repaired all flood damage and has been discussing a restart checklist with the NRC, Hanson said. The earliest the plant could restart would be in the fall, officials said.