Validation and evaluation of the ADVANTG code on the ICSBEP skyshine benchmark experiment

Validation and evaluation of the recently released ADVANTG code, which combines a well-known Monte Carlo (MC) transport code MCNP with a deterministic neutron transport code Denovo, is presented in the paper. The aim of ADVANTG is to automate the process of generating the variance reduction parameters for the fixed source MCNP calculations, which consequently accelerate the simulations in terms of the required CPU time. Reliability and consistent performance of the ADVANTG code were tested on a computationally demanding benchmark, i.e. the skyshine benchmark experiment from the ICSBEP handbook where neutron and photon scattering in the air above an open operating reactor are simulated. The speed-up factors or the increases in relative efficiency of up to 30,000 and 1400 compared to analog MCNP simulations were achieved using the ADVANTG-generated variance reduction parameters for neutrons and photons respectively. As the mean values obtained by the ADVANTG-accelerated simulation sit within the statistical uncertainties of the analog simulation, it was shown that no additional bias is introduced by the ADVANTG code. This article shows that ADVANTG code is a useful and effective tool for use in solving neutral particle transport problems in large geometries featuring skyshine.