Verification of on-the-fly homogenization method based on the analysis of HTTR

Abstract An on-the-fly homogenization (OTFHom) method coupled with depletion based on Monte Carlo method was proposed and implemented in Reactor Monte Carlo code (RMC), which uses continuous energy cross sections to generate multi-group cross sections for specified problems and then uses them in Monte Carlo multi-group calculations to get more convergent results. In order to coupling with depletion, some modifications are made in continuous energy and multi-group calculation procedures to get one-group depletion cross sections and flux for each depletion region. A verification of OTFHom method is carried out to investigate the accuracy and efficiency using HTTR benchmark, which is a prismatic block-type high temperature gas cooled reactor designed by Japan. The criticality and depletion results show that OTFHom method can capture double heterogeneity effect accurately and reduce calculation time considerably because of the spatial homogenization of massive TRISO particles embedded in the graphite matrix. In terms of HTTR model, the time used by CE calculation is about 3 times of that used by OTFHom calculations.