NRC seeks info about fuel at 11 U.S. nuclear reactors including Byron | Reuters

Scott DiSavino Feb 17 (Reuters) - The U.S. Nuclear Regulatory Commission (NRC) said Friday it was requesting information from 11 nuclear plants regarding fuel performance during accidents. The NRC said this was not something that presents an immediate safety concern so there was no reason to shut any of the plants. "But we do want them to come back to us to show they are meeting our regulations," NRC spokesman Scott Burnell told Reuters. The 11 reactors are located at FirstEnergy's Beaver Valley in Pennsylvania, Exelon's Byron in Illinois, Duke Energy's Catawba in South Carolina and McGuire in North Carolina, American Electric Power's Cook in Michigan, and Dominion's Kewaunee in Wisconsin. The 11 plants are customers of U.S. nuclear power company Westinghouse Electric. The NRC's Burnell said there was a fundamental flaw in a computer program Westinghouse used in determining how reactor fuel loses the ability to conduct heat, a phenomenon known as "thermal conductivity degradation." Because of that error there is a possibility that plants could underestimate how hot their fuel could get in an accident, Burnell said. Westinghouse is majority-owned by Japanese multinational Toshiba Corp. "The NRC alerted the industry to this problem in 2009, and Westinghouse needs to do more to account for thermal conductivity degradation in its fuel performance codes," said Eric Leeds, director of the NRC's Office of Nuclear Reactor Regulation, in a statement. "We need assurances from a few nuclear power plants licensees to maintain assurance that they can continue to operate safely with sufficient margin." The NRC said the plants have until March 19 to provide the requested information to the NRC staff. If the information received does not "demonstrate that NRC regulations are met, the staff will recommend imposing restrictions on reactor operating limits until acceptable action has been taken," the NRC said in the statement. The NRC said the thermal conductivity degradation phenomenon could change the performance of the fuel during various accident scenarios, including loss-of-coolant accidents. NOT FUKUSHIMA RELATED Burnell said this request for information from the 11 plants was not related to the Fukushima nuclear accident in Japan last year where some reactor fuel melted down and released radiation. Fukushima was caused by a loss of electric power following an earthquake and tsunami, not a loss of coolant, Burnell said. The NRC said Westinghouse told the agency in December that an analysis the company had conducted indicated there could be thermal conductivity degradation in excess of NRC limits during a worst case loss of coolant accident at a Westinghouse pressurized reactor. The NRC said it also sent copies of the request for information to an additional 23 plants that use the Westinghouse performance models to ensure that they too are aware of their obligations to address this error.

UPDATE 1-NRC seeks info about fuel at 11 U.S. nuclear reactors | Reuters