UWFDM-1343 Analysis of Mesh-Based Neutron Source Models for Better Coupling of Plasma Physics and Neutronics

Developments in computer architecture and neutronics code capabilities have enabled high-resolution analysis of complex 3-D geometries. Thus, accurately modeling 3-D source distributions has become important for performing nuclear analyses. In this work two methods are described which generate and sample such 3-D sources based directly on the plasma parameters of a fusion device and which facilitate the ability to update the neutron source following changes to the plasma physics configuration. The cylindrical mesh method is useful for toroidally symmetric machines and utilizes data in a standard file format which represents the poloidal magnetic flux on an R-Z grid. The conformal hexahedral mesh method takes plasma physics data generated in an idealized toroidal coordinate system and uses a Jacobian transformation and a functional expansion to generate the source. This work describes each methodology as well as associated test cases. The cylindrical mesh method was applied to ARIES-RS and the conformal hexahedral mesh method was applied to a uniform torus and to ARIES-CS. The results of these test cases indicate that the improved source definitions can have important effects on pertinent engineering parameters, such as neutron wall loading, and they should therefore be used for high-resolution nuclear analyses of all toroidal devices.