My research focuses on the computational investigation of special nuclear materials, with particular emphasis on Plutonium Dioxide (PuO₂). Using first-principles density functional theory (DFT) and atomistic simulation techniques, I study both surface and bulk properties to understand gas adsorption, desorption, and transport mechanisms. This includes the effect of extended defects, thermodynamic stability, and changes in oxidation states and electronic structure. The work contributes to long-term nuclear waste storage safety by providing atomic-scale insights into the role of gases during storage.