AN INTERIM STRATEGY FOR THE TREATMENT OF TEMPERATURE-DEPENDENT NUCLEAR DATA IN MONTE CARLO PARTICLE TRANSPORT CODES

摘要

The present work gives an overview of methods used for treating the temperature-dependence of nuclear data used in Monte Carlo neutral particle transport simulations as implemented in the MC21 Monte Carlo code and NDEX data processing system. These methods are based on storing cross sections at discrete temperatures and using interpolation, resulting in higher memory requirements than more recent on-the-fly methods. However, they offer a near-term solution for carrying out high fidelity coupled neutronic-thermal hydraulic simulations until more experience is gained with on-the-fly methods. Methods discussed are categorized by the pertinent energy range: thermal cross sections, epithermal cross sections, free-atom fast cross sections, and unresolved resonance range probability table data. A new method for approximating the Doppler broadened neutron and photon energy release given data at a single temperature is also developed. Finally, comparisons of both differential and integral data show that the temperature interpolation methods used in NDEX/MC21 produce accurate results in the models considered.