Maqarin Phase IV report

Cement and concrete are extensively used in the construction of repositories for low- and intermediate-level radioactive wastes (L/ILW). In underground silos, like those in Sweden and Finland for example, much of the waste is conditioned with concrete (e.g. spent ionexchange resins) and is packed in concrete containers (e.g. Figure 1.1)1. Even in many high-level radioactive waste (HLW) repositories, cement and concrete may be widely used. Instances include the paving of tunnels, shotcreting of tunnel walls, and injection and grouting of fractures. Consequently, in many repository designs, cement-based materials are expected to dominate the repository. In the Swiss L/ILW concept, for example, current designs envisage the use of up to 1.5 million tonnes of cement, approximately 85-90% by weight of the total repository. This will ensure the long-term maintenance of hyperalkaline conditions, predicted to suppress the solubility of key radionuclides in the waste (e.g. Hodgkinson and Robinson, 1987) and to enhance their sorption on the cement (e.g. Stumpf et al., 2004).