SCALE Methodology for Spatially Based Activation of Materials for Transportable Microreactor Applications

Abstract

This study introduces an innovative methodology for spatially-based activation of materials, with a particular focus on addressing the challenges posed by extreme neutron flux variations in environments such as the ground surrounding transportable microreactors. In contrast to the conventional approach within the SCALE framework, which relies on averaging neutron flux across materials, this paper presents a new methodology that leverages neutron flux mesh tallies and voxel-specific material irradiation. After determining the neutron flux distribution, materials are irradiated spatially, with each voxel (3D geometric cell) receiving its own neutron flux. This comprehensive approach leads to the creation of a distributed photon flux source derived from nuclide decay for subsequent dose calculations. The significance of this research lies in its ability to accurately capture the complex spatial distribution of neutron flux in ground environments, a crucial aspect for the design and safety evaluation of transportable microreactors. This methodology ensures that materials are irradiated spatially by the neutron flux based on actual positions, further enhancing the ability to model the environmental impact of transportable microreactors. The proposed approach was validated through a comparison with the standard SCALE approach, demonstrating its precision within acceptable uncertainties. This research paves the way for more accurate safety assessments and informed decision-making in the deployment of transportable microreactors, contributing to the sustainable expansion of nuclear energy solutions.