Upgrading the neutronic version of the PSI cycle check-up methodology for full core PWR Monte Carlo simulations

Abstract

Full core Monte Carlo (MC) simulations are of high interest and can be used to study the beginning of live conditions of reactors. However, current hardware limitations make it difficult to perform such studies for other cycles, as the whole irradiation history of the fuel assemblies (FAs) loaded must be considered on a time scale of several years using MC depletion capabilities. Therefore, at PSI, a cycle check-up methodology (CHUP) is currently being developed to address this challenge. By extracting operating conditions and isotopic compositions from validated reference deterministic core-follow models (using CASMO5/SIMULATE5), MC neutron transport models are generated for selected operating points. These models can then be used to estimate quantities beyond the capabilities of deterministic solvers. This article presents the verification performed on a hot zero power (HZP) operating condition of a Swiss PWR using the newly updated CHUP methodology. This update consists of extracting information generated automatically from reference core models, minimising as much human intervention as possible. The performance of the method was first evaluated against the reference deterministic lattice code. Then, the memory requirements of the full core simulation were studied under different approximations. Finally, verification was performed against the nodal reference scheme.