Verification of Shielding Calculation Capability of RMC With H.B.Robinson-2 Pressure Vessel Benchmark

Abstract

RMC is a 3-D continuous energy Monte Carlo code developed by REAL team in Tsinghua University, China. Besides the capability of fuel cycle burnup calculation, hybrid MPI/OpenMP parallelism strategy, sensitivity and uncertainty analysis, N-TH coupling calculation, shielding calculation methods including general source description, regional importance method, weight window method and source biasing method have been also developed for deep penetration problems. H.B.Robinson-2 Pressure Vessel Benchmark (HBR-2 benchmark) is used for the qualification of pressure vessel neutron flux calculation methods and shielding calculations based on this model have been performed by Monte Carlo codes such as SCALE, MCNPX and deterministic transport code DORT. In this work, the verification calculation of shielding calculation capability of RMC is conducted based on HBR-2 benchmark. The total calculation consists of two stages. Criticality calculation is performed first to obtain the fission neutron distribution in the reactor core assemblies. Then the fission neutron distribution is regarded as the initial neutron source in the following fixed source calculation. Variance reduction techniques such as source biasing and regional importance methods are combined together to be able to reduce the variance of the neutron flux in regions within and outside the pressure vessel including the downcomer and cavity regions. The preliminary calculation results show good agreement with MCNP and the shielding calculation of RMC is justified and applicable for deep penetration problems.