NRC asks reactor owners to reassess accident data
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The U.S. Nuclear Regulatory Commission has asked the owners of 11 Westinghouse nuclear reactors in the U.S., including two owned by FirstEnergy in Shippingport, to analyze whether the nuclear power plants could overheat in the event of a catastrophic accident.
The NRC said Friday it is concerned that aging nuclear fuel used in Westinghouse reactors in Beaver County and elsewhere could have reduced ability to transfer heat and therefore exceed the 2,200-degree Fahrenheit limit in loss-of-coolant accidents.
According to the commission, the fuel's "thermal conductivity degradation" wasn't properly analyzed in performance models done by Westinghouse. The reactor owners have until March 19 to provide the new analysis to the NRC.
"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.
"It's not a safety issue or a concern for the public," said Scott Shaw, a Westinghouse spokesman. "It has to do with how old the fuel being used is. It depends on the fuel cycle of the individual plant. Each devises its core differently."
Mr. Shaw said Westinghouse is working with each customer to determine the impact of the NRC information request and a response.
In December, Westinghouse informed the NRC that a company analysis done at a power plant showed that due to degradation of the fuel its temperature could peak at more than 100 degrees above levels that had been expected in case of a worst-case loss-of-coolant accident.
If the temperature exceeds the 2,200-degree Fahrenheit limit, it could affect the integrity of the cladding, one of three barriers between the fuel rods and the release of radioactivity, said Neil Sheehan, an NRC spokesman.
Jennifer Young, a FirstEnergy spokeswoman, said the Akron, Ohio-based power company is working to "revalidate" the information it has provided to the NRC for Beaver Valley Units 1 and 2, which are located 22 miles northwest of Pittsburgh. It will submit the revised analysis by the deadline.
"We feel comfortable with where we're at," she said. "Each plant has different variables, that's why we're doing the validation modeling."
Mr. Sheehan said that if new computer modeling of a coolant loss accident indicates that peak temperatures of core and cladding exceed the NRC-set limit, reactors could be asked to lower reactor temperatures during operation which would reduce the electric power produced by the plants.
The Beaver Valley reactors produce more than 1,800 megawatts of power. Unit 1 went on line in 1976 and Unit 2 in 1987.
The NRC information request was sent to Westinghouse-designed reactors that had reported peak cladding temperatures above 2,000 degrees Fahrenheit. In addition to Beaver Valley 1 and 2, the NRC contacted Braidwood 2 and Byron 2 in Illinois; Catawba 1 and 2 in South Carolina; Donald C. Cook 1 and 2 in Michigan; Kewaunee in Wisconsin; and McGuire 1 and 2 in North Carolina.
First Published February 18, 2012 12:00 am