OMAHA, Neb. -- A small fire briefly knocked out the cooling system for used fuel at a nuclear power plant in Nebraska, but temperatures never exceeded safe levels and power was quickly restored, federal officials said Wednesday.
The electrical system running the pumps that cool spent fuel in a pool of water was disrupted by a suspected electrical fire Tuesday, though one pump was restored shortly after the incident and another was running Wednesday, utility officials said.
The pumps are a key piece of safety equipment because if pumping systems fail for several days and are not fixed, cooling water could boil away and eventually cause radioactive releases.
While a diesel-powered backup pump was available at the Fort Calhoun Station, it was not needed, said Mike Jones, a spokesman for the Omaha Public Power District, which operates the plant. No radiation was released and no other significant damage was reported.
Nuclear Regulatory Commission spokesman Eliot Brenner said power was restored to the first pump in about two hours, although the utility said it took only one hour.
Fort Calhoun's fuel pool was not physically damaged, and the utility estimated it would take about 80 hours before the pool water started boiling and evaporating, giving workers time to react.
The reactor was shut down in April for refueling and has not restarted because of rising water along the Missouri River. Federal officials said temperatures in the pool never topped 83 degrees.
"It was not even tepid bath water," Brenner said.
Nebraska state officials were notified, but the utility was able to control the fire before any significant state response was needed.
"What I saw is, from our perspective, that the emergency procedures at Fort Calhoun were activated, utilized and initiated per plan in response to the incident," said Al Berndt, assistant director of Nebraska Emergency Management Agency. "In that regard, I'm very comfortable with what happened."
The incident comes after the crisis at the Fukushima Dai-ichi nuclear plant in Japan prompted U.S. regulators and industry officials to re-examine the safety of storing nearly 55,000 tons of spent, radioactive fuel in water pools across the country.
Analysts have long recommended that spent fuel be removed from pools after several years and placed into dry casks that sit on land. Shifting fuel into dry storage would reduce the amount of radioactivity that could be released during an accident at a pool, said Robert Alvarez, a scholar at the Institute for Policy Studies who studies the issue. Dry casks are more resistant than pools to accidental damage or a terrorist attack.
While Alvarez, a former policy advisor to U.S. energy secretary, said losing pumps for an hour is not a crisis, he said the incident raises larger policy issues.
"Every time one of these things happens, you've got to ask yourself when's a more serious event going to happen?" he said.
Pools at most nuclear plants hold several times more spent fuel than originally intended. When the current fleet of nuclear plants was built, the pools were considered a temporary storage option. It was assumed spent fuel would be taken away, either for reprocessing into fresh fuel or shipped to underground repositories.
Those plans were dashed. President Jimmy Carter banned the reprocessing of nuclear fuel over fears that the technology would enable more countries to build nuclear weapons. President Barack Obama's administration has cancelled a long-stalled plan to complete an underground repository for used nuclear fuel at Yucca Mountain in Nevada.
Henry reported from Atlanta. Associated Press writer Matthew Daly in Washington contributed to this report.