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

By 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.