Federal regulators expressed serious concerns about a fire that briefly put the cooling system for used nuclear fuel out of commission at an idled Nebraska nuclear plant last summer.

Temperatures during the fire never exceeded safe levels, the Nuclear Regulatory Commission said in a new report, but workers failed to adequately look into an unusual smell in the area days before the fire. The commission said an investigation could have revealed the problem: an ill-fitting electrical breaker.

A serious threat finding generally requires a nuclear plant to undergo more oversight. But the Fort Calhoun plant north of Omaha is already under the commission's strictest level of oversight as a result of other problems. Fort Calhoun initially was shut down for refueling maintenance last spring, but major flooding nearby forced it to stay closed.

A representative from the Omaha Public Power District said the utility is moving toward restarting the plant during the spring, but it will not do so before it is safe (Josh Funk, AP/San Francisco Chronicle, March 12). -- WW