Follow up to previous postings on nuclear energy, this news release: “The Nuclear Regulatory Commission has issued a Request for Information (RFI) to 11 nuclear power plants, requesting analyses of the effects of irradiation on nuclear fuel’s physical properties under certain postulated accident conditions. The agency is requesting the licensees evaluate a phenomenon known as “thermal conductivity degradation” – the fact that older fuel has a reduced capacity to transfer heat, potentially changing its performance during various accident scenarios, including loss-of-coolant accidents. The NRC is concerned that this phenomenon may not have been accounted for in realistic performance models for nuclear fuel developed by Westinghouse Electric Co. NRC regulations set a fuel thermal limit of 2,200 degrees Fahrenheit for “peak cladding temperature” under predicted loss-of-coolant accident conditions. Above that limit, the fuel rod is considered susceptible to damage. Thermal conductivity must be accounted for in realistic computer models used to evaluate a reactor’s emergency core cooling system. An error in the models may underestimate the fuel’s calculated peak cladding temperature. An error is considered significant if it would result in a difference of 50 degrees F or more in the predicted peak cladding temperature during the worst postulated loss-of-coolant accident scenario.”