An Approach for Validating Actinide and Fission Product Burnup Credit Criticality Safety Analyses-Criticality (keff) Predictions

Taking credit for the reduced reactivity of spent nuclear fuel (SNF) in criticality analyses is referred to as burnup credit (BUC). Criticality safety evaluations require validation of the computational methods with critical experiments that are as similar as possible to the safety analysis models, and for which the keff values are known. This poses a challenge for validation of BUC criticality analyses, as critical experiments with actinide and fission product (FP)
nuclides similar to SNF are not available. To address the issue of validation for nuclides that lack experimental data (e.g., minor actinides and FPs) the US Nuclear Regulatory Commission initiated a project with the Oak Ridge National Laboratory to establish and demonstrate an approach that could be used for commercial SNF criticality safety evaluations based on bestavailable data and methods. This report describes how model-specific sensitivity data can be
used to translate nuclear data uncertainties into uncertainty in the model keff value.