Monte Carlo (MC) based neutron transport codes provide high-fidelity numerical solutions to problems
beyond the modelling capabilities of conventional core simulation methods. However, performing core-follow
calculations with MC codes remains challenging due to the necessity of incorporating thermal-hydraulic
feedback and generating evolved fuel composition for the cycle of interest by taking into account the entire
irradiation history of loaded fuel assemblies over previous cycles. Nevertheless, at PSI, the neutronic version
of a cycle check-up methodology (CHUP) is under development to address this challenge. This methodology
involves extracting operating conditions and nuclide compositions from validated reference deterministic corefollow models (CASMO5/SIMULATE5/SNF), subsequently generating MC neutron transport models for selected
operating points. This article presents the verification and validation performed for a hot zero power operating
condition of a Swiss pressurised water reactor using the updated CHUP methodology, which automates
information extraction from reference core models to minimise human intervention. The MC models were
verified by assessing their deviation from criticality, consistently found to be supercritical within the [10,60]
pcm range. Additionally, radial relative power distribution verification yield deviations in the [−5,4] % range
compared to validated nodal results. Finally, additional validation was performed using start-up measurements
from two successive cycles. Eight MC models were found to be subcritical, on average by 51 pcm, with a
standard deviation of 25 pcm.