Analytic Treatment of Intra-Fuel-Rod Temperature Distributions in the GPU-Based Continuous Energy Monte Carlo Code PRAGMA

摘要

A practical scheme for the analytic treatment of intra-fuel-rod temperature distributions was implemented in the GPU-based continuous energy MC code PRAGMA. Simple polynomial fitting was used to describe the fuel temperature distributions for practicality, which eventually turned out to have sufficient accuracy. In order to perform tracking with the continuous temperature distributions, a localized delta tracking approach using temperature majorant microscopic cross sections was introduced. The accuracy of the scheme was verified against a fine-mesh calculation using a pin cell problem, and its performance was examined with a realistic 3D full-core simulation, whose result substantiated that it is as efficient as using no intra-pellet regions at all while fully reflecting continuous temperature distributions. Therefore, the suggested scheme can be effectively utilized in large-scale MC core analyses to achieve higher fidelity.