UNCERTAINTY AND SENSITIVITY ANALYSIS IN CRITICALITY CALCULATIONS WITH PERTURBATION THEORY AND SAMPLING

摘要

The paper presents uncertainty and sensitivity analyses in criticality calculations with respect to nuclear data performed with the SCALE module TSUNAMI based on general perturbation theory, and the tools SAMPLER, to be available with the next SCALE release, and XSUSA; the latter are based on a random sampling approach. The investigation mainly uses one-dimensional systems where computation times are low; nevertheless, results are given also for critical assemblies in three-dimensional representation. Results from the three tools are compared for a variety of output quantities, namely multiplication factors, reactivity effects, and one-group cross sections. The arrangements under consideration cover a wide variety of fuel and coolant materials with very different neutron spectra. For all systems and all output quantities considered, excellent agreement is obtained with all the tools. The sampling-based results are practically identical; deviations between the TSUNAMI and the sampling-based results are generally very low, too, with rare exceptions where the deviations are slightly larger than the 95% confidence interval of the sampling methods. In total, the results from the different methods appear to be completely consistent.