Heterogeneous 3-D SN transport reactor calculations using Attila

The Canadian Nuclear Safety Commission (CNSC) is preparing to license diverse reactor technologies (CANDU, LWR, small/research reactors). To this end, the CNSC has acquired the Attila SN transport code to serve as an independent tool in licensing reactor design evaluation. In this paper, we are presenting 3-D large scale parallel benchmark calculations of a small PWR with MOX using Attila SN transport code and their comparison to MCNP Monte Carlo. Our benchmark is that of Nam Zin Cho et al transformed into a new 3-D hexagonal geometry heterogeneous benchmark. It provides an evaluation of Attila code in complex calculations of power reactor core with MOX. In this benchmark, we computed using Attila the keff of the core with Control Rods and generated the assembly and pin powers choosing the pins placed in strong transport boundary layer effect zones. As a reference solution, the Monte Carlo MCNP calculations were obtained. The results show that the full core parallel heterogeneous 3-D SN transport calculations of a power reactor are feasible on a small workstation. Our keff results are within 0.8% (800 pcm) relative difference to MCNP reference result (0.9919) and assembly and pin power results are on the average about 2% and 3.6% different. These results validate the Attila code for nuclear design and licensing work. (author)