Continuous-energy multidimensional S-N transport for problem-dependent resonance self-shielding calculations

摘要

A method is presented to obtain a continuous-energy representation of the neutron spectrum using two-dimensional discrete ordinates calculations with a combination of multigroup (MG) and point-wise (PW) nuclear data. This provides the capability of determining the fine-structure energy distribution of the angular flux and flux moments within the resonance range as well as the smoother spectrum in the high- and thermal-energy ranges. The continuous-energy flux spectra can be utilized as problem-dependent weighting functions within the whole two-dimensional domain to process self-shielded MG cross sections for reactor physics and/or criticality safety analysis so that the two-dimensional heterogeneous effect in the resonance calculation can be fully considered. This calculational method has been implemented in a new PW transport code called GEMINEWTRN that may be executed as a module in the SCALE computer code system. Example applications using ENDF/B cross-section data are presented to study the two-dimensional heterogeneous effect in the resonance calculations.