Validation of spent-fuel isotopics predicted by the SCALE-4 depletion sequence

The Standardized Computer Analyses for Licensing Evaluation (SCALE) code system is used extensively to perform away-from-reactor safety analyses (particularly criticality safety, shielding, and heat transfer analyses) for spent light water reactor fuel. Spent-fuel characteristics, such as radiation sources, heat generation sources, and isotopic concentrations, can be computed within SCALE using the SAS2 control module. At user-defined time steps, the SAS2 sequence performs a radiation transport analysis (via XSDRNPM-S) to obtain appropriate cross sections and spectral parameters for an ORIGEN-S point-depletion analysis. Each ORIGEN-S case produces the burnup-dependent fuel composition to be used in the next spectral calculation. Thus, the burnup-dependent cross sections and spectral parameters generated for ORIGEN-S are dependent on the initial enrichment, specified power history, and assembly model input to SAS2. A final ORIGEN-S case is used to perform the complete depletion/decay analysis using the burnup-dependent cross sections developed by the iterative scheme. The latest version of the SAS2 control module as released with SCALE-4 is denoted SAS2H. The purpose of this paper is to report recent SAS2H/ORIGEN-S calculations that were performed to compare pressurized water reactor (PWR) spent-fuel isotopic concentrations with measured data determined by radiochemical analyses