Sensitivity/Uncertainty Analysis for BWR Configurations of Exercise I-2 of UAM Benchmark

Abstract

In order to evaluate the uncertainties in prediction of lattice-averaged parameters, input data of core neutronics codes, Exercise I-2 of the OECD benchmark for uncertainty anal-ysis in modeling (UAM) was proposed. This work aims to perform a sensitivity/uncertainty analysis of the BWR configurations defined in the benchmark for the purpose of Exercise I-2. Criticality calculations are done for a 7x7 BWR fresh fuel assembly at HFP in four configurations: single unrodded fuel assembly, rodded fuel assembly, assembly/reflector and assembly in a color-set. The SCALE6.1 code package is used to propagate cross section covariance data through lattice physics calculations to both k-effective and two-group assembly-homogenized cross sec-tions uncertainties. Computed sensitivities and uncertainties for all configurations are analyzed and compared. It was found that uncertainties are very similar for the four test-problems, showing that the influence of the assembly environment on uncertainty prediction is very small.