Atlas

Interim storage of spent nuclear fuel (SNF) in Germany will extend beyond the year 2060, far exceeding the originally planned duration of 40 years. This poses challenges for ensuring the integrity of the fuel, particularly regarding high-burnup fuel (>55 GWd/tSM) and MOX fuel. These fuel types account for over 10% of Germany's SNF inventory. They exhibit complex microstructural heterogeneities as well as higher inventories of fission products and minor actinides, factors that can influence oxygen potential, gas diffusion, and the mechanical stability of fuel rods over time. However, international experience with the long-term storage of these fuel types is limited, and existing safety criteria developed for shorter storage periods require validation for extended timeframes. The ATLAS project uses a bottom up approach of combining fundamental experiments with simulation methods in order to generate meso- and engineering-scale data can be used to verify and support the storage of SNF over extended periods.