IMPACT OF RAY EFFECTS ON A~3 MCNP PERFORMANCE FOR A PURELY ABSORBING MEDIUM WITH VOID REGION

摘要

This paper analyzes the performance of A~3MCNP? (Automated Adjoint Accelerated MCNP)rnfor a purely absorbing medium with void region. A3MCNP? is based on the CADISrn(Consistent Adjoint Driven Importance Sampling) methodology, which uses a deterministic 3-rnD importance function, to determine variance reduction parameters. A3MCNP?rnautomatically prepares necessary input files for adjoint transport calculation using the TORTrndiscrete ordinates (SN) code. In a purely absorbing medium with void region, the SN methodrnsuffers from the ray effects. The impact of the ray effects on the performance of A3MCNP?rnis investigated using different uniform mesh distributions. It is demonstrated that for anrnadjoint function distribution with no oscillation (ray effects), A3MCNP? can yield significantrnspeedups over an analog Monte Carlo calculation, for a medium containing pure absorberrnand void regions.