Explicit Treatment of Thermal Motion in Continuous-Energy Monte Carlo Tracking Routines

摘要

This paper introduces a new stochastic method for taking the effect of thermal motion into account on the fly in a Monte Carlo neutron transport calculation. The method is based on explicit treatment of the motion of target nuclei at collision sites and, consequently, requires simply cross sections at a temperature of OK regardless of the number of temperatures in the problem geometry. It utilizes rejection sampling techniques to manage the fact that total cross sections become distributed quantities. The method has a novel capability of accurately modeling continuous temperature distributions. The new stochastic method is verified using a simple test program, which compares its results to an analytical reference solution based on NJOY-broadened cross sections. Future implementation to Monte Carlo reactor physics code Serpent is also discussed shortly.