DBRC and WCM scattering kernels for TRIPOLI-4, version 9

CEA/Saclay, DEN/DM2S/SERMA, 91191 Gif-sur-Yvette Cedex, France

Abstract

Recent works have pointed out some relevant shortcomings of the so called ‘Sampling of the Velocity of the Target nucleus’ (SVT) algorithm, which is currently used in most Monte Carlo codes for the Doppler broadening of the elastic scattering kernel. To overcome these limitations, which affect resonant nuclei such as ²³⁸U, and whose consequences in pincell criticality calculations can amount to a drop of a few hundred pcm, the Doppler Broadening Rejection Correction (DBRC) and the Weight Correction Method (WCM) have been proposed. In this work, we illustrate the implementation of DBRC and WCM in the TRIPOLI-4 Monte Carlo code. Several validation tests are discussed, and the impact of using DBRC or WCM to replace SVT is analyzed in detail in static as well as burnup calculations for UOX and MOX pincells, and in a PWR full-core simulation.