Innovative and new container/canister materials under disposal fields conditions: manufacturing feasibility and improved durability (InCoMand)

Deep geological disposal of high-level waste (HLW) will subject the container to various challenges, corrosion resistance being one of the most crucial. HLW components lifetimes are typically calculated based on the time-dependent corrosion behaviour alone, with the implicit assumption that the component has been designed to remain structurally stable over extremely long periods. However, for some component materials and designs, there may be significant interactions between mechanical and corrosion degradation modes that could affect the ultimate failure time. Even though the durability of several component materials subjected to corrosion processes have been previously studied in detail, the interaction of mechanical processes and corrosion calls for further study, and assessment of the impact of joint degradation modes on component lifetimes will result in a more robust and defensible safety case. Besides, as corrosion occurs in a thin interfacial surface layer between the component outermost surface and the environment, specific R&D work is required to understand the long-term performance controlled by the entire engineered barrier system (EBS). Indeed, this latter is complex, made of different materials (excluding here the containers), for instance the host rock and cement-based materials (backfills, buffers), and characterized by various, impactful conditions such as the water chemistry, the microbial activity, the stress load, the temperature, the radiation sources…).

Another approach to tackle the corrosion issue is to prevent and/or minimize it, thereby ensuring an even safer disposal. In this approach, materials much less prone to corrosion (e.g., ceramic materials) can be used to fabricate the containers. Alternatively, protective coatings can be applied to current selected reference materials. Both ways require selection of the relevant materials and of the fabrication/deposition methods and validation of the materials durability under realistic, accelerated field conditions.

The objective of this WP is to identify and qualify novel materials for the HLW containers/canisters, as well as providing a deeper knowledge of both traditional and novel materials long-term durability in, as realistic as possible, field conditions.