The HORIZON 2020 EURATOM Collaborative Project “Cement-based materials, properties, evolution, barrier functions (CEBAMA)” was developed to support the implementation of nuclear waste disposal in deep underground facilities. Radioactive waste poses potential health hazards and risk to the biosphere including humans. The best way to handle and dispose this material is a topic of broad public debate and concern. Supporting safe options for the long-term disposal of nuclear waste is therefore a key component in developing sustainable strategies to implement nuclear energy as part of the energy mix in Europe but also within decisions to finally phase out the use of nuclear energy.
Cement-based materials are highly relevant for the nuclear waste disposal Safety Case, because they are widely used in a repository, e.g. as waste matrix, liners and structural components or sealing materials. In order to make reliable assessments of the potential evolution and performance of a repository with time, it is important to understand the specific chemical and physical processes affecting cement materials and their effect on radionuclide behaviour and migration. Specific technical questions tackled within CEBAMA were:
- How do cement-based materials affect the isolation properties of other barriers, like the host rock and the clay backfill material? Experimental studies were performed to understand the interface processes between cement-based materials and the host rocks (crystalline rock, Boom Clay, Opalinus Clay, Callovo-Oxfordian) or bentonite backfill and assess the impact on physical and geochemical properties.
- How do specific radionuclides or toxic elements of interest behave in the presence of cement-based materials, or in media altered by the presence of these materials? Experimental studies were performed with relevant elements (Be, C, Cl, Ca, Se, Mo, I, Ra) in cement-driven environments.
- How well are we able to predict changes in transport properties coupled with chemical and physical processes on the cementitious matrix or in the cement host rock interface? Modelling work performed in CEBAMA supported advanced data interpretation and process modelling, covering mainly physical and chemical processes responsible for the changes in transport properties and extrapolate the models to different scales for application in Safety/Performance assessment.
