IMPROVED WEIGHT WINDOW VARIANCE REDUCTION FOR COUPLED RADIATION MONTE CARLO TRANSPORT CALCULATIONS

摘要

This paper presents an improvement for traditional weight window variance reduction in coupled radiation Monte Carlo transport calculations. The improved technique automatically adjusts the number of secondary particles created at each collision in order to ensure that the birth weight of each secondary particle falls within the weight window limits for the type, energy, direction, and location of the emitted radiation. The proposed technique simplifies the process for defining, applying, and optimizing radiation-specific space/energy importance definitions in coupled-radiation problems. Testing on a simplified problem demonstrates that the proposed adaptive-yield technique is effective even for deep-penetration coupled-radiation calculations that include many generations of secondary radiation.