Validation of BWR spent nuclear fuel isotopic predictions with applications to burnup credit

Abstract

Validating boiling water reactor (BWR) spent nuclear fuel inventory calculations is challenging due to the complexity of BWR assembly designs, the lack of publicly available radiochemical assay measurements, and limited access to documentation on fuel design and operating conditions. This study compiled and evaluated experimental data on measured nuclide concentrations in commercial spent fuel for 77 fuel samples that cover a wide range of modern assembly designs and operating conditions. These data were used to validate predictions of the isotopic content using the SCALE Polaris lattice physics depletion code. The isotopic bias and uncertainties derived from comparisons of calculated and measured nuclide concentrations are applied to estimate the combined effect on the effective neutron multiplication factor for a representative burnup credit spent nuclear fuel storage system. The experimental data, validation results, model uncertainties, and uncertainty analysis results for a cask burnup credit application system are described.