Application of 3-dimensional radiation transport codes to the analysis of the CRBR prototypic coolant pipe chaseway neutron streaming experiment

This report summarizes the calculational results from analyses of a Clinch River Breeder Reactor (CRBR) prototypic coolant pipe chaseway neutron streaming experiment Comparisons of calculated and measured results are presented, major emphasis being placed on results at bends in the chaseway. Calculations were performed with three three-dimensional radiation transport codes: the discrete ordinates code TORT and the Monte Carlo code MORSE, both developed by the Oak Ridge National Laboratory (ORNL), and the discrete ordinates code ENSEMBLE, developed by Japan. The calculated results from the three codes are compared (1) with previously-calculated DOT3.5 two-dimensional results, (2) among themselves, and (3) with measured results. Calculations with TORT used both the weighted-difference and nodal methods. Only the weighted-difference method was used in ENSEMBLE. When the calculated results were compared to measured results, it was found that calculation-to-experiment (C/E) ratios were good in the regions of the chaseway where two-dimensional modeling might be difficult and where there were no significant discrete ordinates ray effects. Excellent agreement was observed for responses dominated by thermal neutron contributions. MORSE-calculated results and comparisons are described also, and detailed results are presented in an appendix.