Solving Three-Dimensional Large-Scale Neutron Transport Problems Using Hybrid Shared-Distributed Parallelism and Characteristics Method

The design of new generations of nuclear reactors will involve fine representations of the theoretical models. Advanced computational methods capable of solving large-scale problems dealing with large and complex systems are required. Therefore, the solution to challenging large-scale neutron transport problems is becoming more and more pressing in nuclear engineering applications. The increase in high-performance computing resources have made possible direct application of transport methods to large-scale computational models. However, many numerical acceleration techniques common to lattice transport codes are not applicable to three-dimensional geometries with heterogeneous material zones, especially for the eigenvalue problems with high-dominance scattering ratio. Consequently, large heterogeneous reactor problems have remained computationally intensive and impractical for routine engineering applications. One of the alternatives is to use high-performance computing methods to solve such problems in reasonable time.

In this context, we propose an approach based on high-performance computing techniques to solve large-scale neutron transport problems using a three-dimensional characteristics method. A performance model is then introduced to analyze the three-dimensional characteristics solvers in the context of hybrid shared/distributed memory modern architectures. Several numerical results and discussions are presented including a scalability analysis done to predict the performance on a large number of processors.