Massively Parallel Method of Characteristics Neutron Transport Calculation with Anisotropic Scattering Treatment on GPUs

Even for the significant advances in CPU computing power and high performance computing, direct whole-core neutron transport calculation still remains unfeasible for the industrial applications. Furthermore, the improving trend of CPU technology is being challenged nowadays by thermal and power constraints. Thus, heterogeneous computing is increasingly receiving attention as an alternative for reactor physics. This work suggests a method to accelerate method of characteristics neutron transport calculation with anisotropic scattering treatment on GPUs. The method was implemented in nTRACER, a direct whole-core neutron transport calculation code being developed by Seoul National University. Performance results on VERA benchmark problem #5 P1 and P2 calculation presented 10-13 times speedup on GPU with adequate support of CPU compared to original CPU solver with 16-core parallel calculation. It was demonstrated that even an entry-level commercial GPU can be used as an effective means of reactor physics analysis if CPU -- GPU concurrency and single precision are properly utilized.