Geochemical optimisation of a disposal system for high-level radioactive waste

Geochemical exploration commonly utilises observations from nature to help find, and explain the genesis of, anomalies such as ore bodies. Radioactive waste disposal involves the inverse process of using such expertise to design a geochemical anomaly (the repository) which will persist for geological timescales. The particular challenge is developing a disposal concept which is “robust” — based on materials and processes which can be relied upon to function in a predictable manner.With regard to long-term performance, experience has indicated that geochemical barriers generally tend to be more robust in this sense than mechanical or hydrological barriers. They are also often easier to support with natural analogue arguments. With the aim of developing a practical design of engineered barriers which will provide convincing long-term safety in a wide range of geological environments, optimisation of the materials under consideration is examined from a geochemical perspective.