Radionuclide Migration in the Far-Field: The Use of Research Results in Safety Cases

In the Integrated Project FUNMIG fundamental processes governing radionuclide migration in the geosphere were investigated. Within the RTD Component 6 the involved Waste Management Organisations (WMOs) and an Integration Monitoring Group coordinated the linking of the scientific work performed in the Components 1 to 5 to its use in performance assessment and monitored the improvements achieved within this project for the safety cases of the individual radioactive waste disposal programmes in Europe. Boundary conditions for the near-field of a radioactive waste repository, in particular radionuclide fluxes and concentrations but also repository induced perturbations of the geosphere, were defined based on the WMOs' safety cases and on the outcome of the European Project NF-PRO. A comprehensive catalogue providing concise information for each task performed in FUNMIG was compiled. It facilitates the retrieval of knowledge acquired within FUNMIG and was used to map these tasks to internationally accepted lists of Features, Events and Processes (FEPs) for clay-rich, crystalline and salt host rocks. The subsequent evaluation revealed issues important for future safety cases, namely the mechanistic understanding, quantification and up-scaling of radionuclide diffusion in clay-rich host rocks and, for crystalline host rocks, the influence of colloids on radionuclide transport and the up-scaling of reactive transport modelling in fractured systems. Finally, the scientific outcome of FUNMIG was synthesised for each of the three host rocks by collecting the individual tasks in Super-FEPs. The transferability of knowledge between the host rocks is limited due to the host rock and site specificity of the research performed in FUNMIG.