Polaris: A new two-dimensional lattice physics analysis capability for the SCALE code system

Polaris is a new 2-dimensional (2-D) lattice physics capability in the SCALE code system for the analysis of light water reactor fuel designs. In this paper, the Polaris calculational methods are summarized and results are provided for a series of computational benchmarks. The summary includes the implementation of the relatively new resonance self-shielding approach called the embedded self-shielding method, the implementation of a new 2-D method-of-characteristics neutron transport solver, and the integration of the SCALE/ORIGEN depletion and decay solver for depleting material compositions. Polaris calculations are compared with reference continuous energy Monte Carlo solutions for a UO₂ fuel computational benchmark. Because Polaris is integrated into the SCALE code system, Polaris has been utilized as part of the new SCALE/Sampler code sequence, which provides stochastic uncertainty analysis for the impact of cross-section uncertainties on lattice physics calculations. SCALE/Sampler results are summarized for selected benchmark calculations.