Angular adaptive discrete ordinates method for deuterium–tritium neutron streaming experiments simulating narrow gaps

Abstract Shielding analyses for fusion reactors pose significant computational challenges, including strong anisotropic scattering and a combination of deep-penetration shielding and complex channeling. The discrete ordinates method is one of the most widely used techniques to solve the linear Boltzmann equation. We propose a regional angular adaptive algorithm to reduce angular discretization errors for shielding calculations. Angular adaptive refinement techniques are based on estimated local errors. The local errors are weighted by the importance distribution toward the computational goal, providing an appropriate goal-oriented adaptivity. The accuracy of this algorithm with FENDL/MG-3.0 libraries was investigated through analyses of streaming experiments with deuterium–tritium neutron sources at JAERI/FNS. From comparing reaction rates of measurements and calculations, the angular adaptive algorithm suffices in predicting the fast neutron field inside the gap. The solutions show that the algorithm can improve the accuracy of calculation results.