Deterministic Two-Dimensional MOX Fuel Assembly Transport Calculations Without Spatial Homogenization

As part of the effort for testing the ability of current transport codes to treat reactor core problems without spatial homogenization, the lattice code HELIOS was employed to perform criticality calculations. A basis for testing was seven-group form of the C5 MOX fuel assembly problem specified by Cavarec et. al. [1]. The problem, known as C5G7 MOX Benchmark is described in the Benchmark Specification [2] and comprises two cases - two and three-dimensional geometry. There are four fuel assemblies - two of them are MOX fuel assemblies and the other two are uranium dioxide assemblies. Each fuel assembly is made up of a 17x17 lattice of square fuel-pin cells. Fuel pin compositions are specified in the Benchmark Specification, which also provides seven-group transport corrected isotropic scattering cross-sections for UO₂, the three MOX enrichments, the guide tubes, the fission chamber and the moderator. This paper presents the methodology employed in solving the C5 MOX Fuel Assembly Problem using the transport code HELIOS. It presents results of eigenvalues calculation and also the pin powers using the Benchmark cross sections library and the specified geometry. (author)