A Statistical Sampling Method for Uncertainty Analysis with SCALE and XSUSA

TLDR

The Sampler/XSUSA methodology is presented, with example applications to criticality safety and spent‑fuel analysis. XSUSA samples uncertainty data from the SCALE covariance library to generate random multigroup cross‑section values, which Sampler uses to compute perturbed self‑shielded cross sections and propagate them through any SCALE analysis sequence, then statistically analyzes the output distributions to quantify uncertainties and correlations. The Sampler, a new statistical sampling sequence for SCALE, has been developed and demonstrated to provide uncertainty and correlation estimates for criticality safety and spent‑fuel analyses.

Abstract

A new statistical sampling sequence called Sampler has been developed for the SCALE code system. Random values for the input multigroup cross sections are determined by using the XSUSA program to sample uncertainty data provided in the SCALE covariance library. Using these samples, Sampler computes perturbed self-shielded cross sections and propagates the perturbed nuclear data through any specified SCALE analysis sequence, including those for criticality safety, lattice physics with depletion, and shielding calculations. Statistical analysis of the output distributions provides uncertainties and correlations in the desired responses, due to nuclear data uncertainties. The Sampler/XSUSA methodology is described, and example applications are shown for criticality safety and spent-fuel analysis.