The fate of chemicals in the environment is of importance in fields, including fuel-cycle or radioecology. Migration models describe the behaviour of radionuclides and relationships with properties: e.g. electrical charge, redox state. In addition, the retention on mineral surfaces strongly delays migration. This later mechanism may be described using various approaches and levels of complexity:
- Non-reactive approach, considering retention (Kd) without species chemistry,
- Reactive-transport, considering speciation in solution and on surfaces,
- Multi-component approaches, specifying diffusion for each compounds, e.g. NO3, EDTA, Th(IV), etc.
- Multi-species approaches, specifying the behaviour of each species for a given compound, e.g. [UO2] 2+, [CaUO2(CO3)3]2-, [Ca2UO2(CO3)3]0.
The work will focus on the development of multi-component and multi-species migration models. Models will be applied to assess more accurately the spread of chemical perturbations in natural barriers (soils, sediments). To this aim, available experimental data will be used as input data. A main objective is to quantify the differences between approaches and potential implications for radionuclide migration & corresponding mitigation strategies.