Research Objectives The primary objective of this project is to utilize high-performance computing (HPC) resources to bridge the gap between experimental NDA data and predictive computational modeling. Specifically, this work focuses on: Advanced Burnup Credit Analysis: Leveraging the SCALE (Standardized Computer Analyses for Licensing Evaluation) and Serpent 2 codes to refine isotopic depletion calculations. Improved accuracy in predicting actinide and fission product inventories is vital for the realistic determination of reactivity margins in spent nuclear fuel storage and transport casks. Detector Response Modeling: Utilizing the MCNP (Monte Carlo N-Particle) code to perform detailed transport simulations of neutron and gamma-ray detector systems. By creating high-fidelity digital twins of assay equipment, we aim to optimize detector efficiency, reduce measurement uncertainties, and enhance the capability to detect diversion of nuclear materials. Methodology and Computational Requirements Monte Carlo methods, while inherently accurate due to their ability to model complex geometries with minimal approximation, are computationally intensive. To achieve the statistical precision necessary for safeguards applications—where signal-to-noise ratios are often low—we require variance reduction techniques such as weight window generation and weight splitting. These methods require significant iterative computational cycles to optimize parameters before production runs. The research will employ a multi-code strategy: Serpent 2 will be utilized for high-throughput, continuous-energy burnup calculations due to its optimized handling of large-scale depletion problems. SCALE (ORIGEN/KENO) will provide a standardized framework for regulatory-consistent depletion and criticality safety assessments. MCNP will be reserved for complex, three-dimensional detector geometries and pulse-height tally simulations, which are demanding on CPU time per particle history. Given the need to perform large parametric sweeps—essential for sensitivity analysis—we anticipate a total requirement of approximately [Insert Number, e.g., 2,000,000] core-hours over the next allocation period. These resources will enable the execution of high-fidelity models that are currently intractable on local institutional clusters. Impact on Safeguards The outcomes of this research will provide the Swedish nuclear community and international partners with validated computational methodologies. By enhancing the predictive power of M&S, this project directly supports the development of more robust, transparent, and efficient safeguards technologies. Ultimately, these simulations provide the quantitative backbone for verifying the peaceful use of nuclear energy in an era of increasing proliferation challenges.