Performance Improvement of Weight Window Method by Incorporating DXTRAN

This study introduces a novel DXTRAN-based weight window generator (DWWG) for variance reduction in Monte Carlo (MC) radiation shielding calculations implemented in the MCS code developed at Ulsan National Institute of Science and Technology. DWWG eliminates the iterative generation required by traditional weight window generators (WWGs) while ensuring target region scoring through the embedded DXTRAN. By incorporating virtual tracks of DXTRAN into the importance estimation, DWWG produces high-quality weight windows. Performance verification of two radiation shielding problems demonstrated that weight windows generated by DWWG, when combined with direct simulation or DXTRAN, yielded increased figures of merit and reduced relative standard deviations. These results establish DWWG as an effective WWG for variance reduction in MC simulations.