PWR fuel debris filtering performance measurement method and its application

•Test requirements are derived to provide guidelines that could minimize test results deviation between test programs.•Binomial probability theory was introduced to analyze debris-filtering test results.•A guide to determine the number of required objects is suggested, considering the constraints such as confidence interval and surrounding geometries.•Various kinds of wire debris test were performed, and the results are discussed.•Wire debris diameter tolerance was calculated based on the statistical evaluation.

This paper concerns a nuclear fuel debris-filtering test methodology based on experimental statistics. In nuclear power plants worldwide, one of the main fuel-failure mechanisms is debris-induced fuel failure. Therefore, fuel vendors have introduced several debris-filtering designs in their fuel, and they evaluate the filtering efficiency using in-house test methodologies. However, the debris is not uniform in shape and dimension. In general, an in-house method would not be applicable for a fair evaluation of other vendor's fuels. To provide a more objective-oriented test methodology, debris-filtering test requirements are proposed, and a generalized test method including a reference debris specimen is discussed. The required number of debris specimens is also discussed, considering the statistics, manufacturability, and other constraints. A filtering evaluation method is also provided. Many tests were performed with different wire dimensions to verify the suggested method, and the results are also discussed. The debris-filtering test results show that the suggested requirements could be realized, and the method could be applicable for a fair evaluation of the fuel performance.