Investigation and Validation of Spectral History Model in SCIENCE V2

Accurate modeling of spectral history effects in Pressurized Water Reactors (PWRs) is crucial to improve fuel cycle predictions and optimize core performance. This study investigates the impact of spectral history model on neutron transport calculations using SCIENCE V2, a computational tool for nuclear reactor analysis. The methodology includes the reconstruction of multi-parametrized libraries through a stepwise approach: fuel depletion simulations, restart calculations (branching), and bilinear interpolation techniques. A detailed sensitivity analysis is performed to assess the influence of state parameters, such as moderator density, fuel temperature, boron concentration, and spectral index, on plutonium production and cross-section variations. The study demonstrates that local parameters, but also environmental factors, including the presence of neighbouring assemblies and control rods, significantly alter local neutron spectra, thus affecting fuel depletion and isotopic composition. The validation phase employs APOLLO3® calculations to benchmark SCIENCE V2 configurations, confirming the model’s capability to capture spectral history effects with high fidelity. This research provides a refined methodology for improving nuclear simulations' accuracy, enhancing reactor safety, and operational efficiency.