XRD Analysis of Cement Paste Samples Exposed to the Simulated Environment of a Deep Repository

Portland cement materials are widely used as engineered barriers in repositories for radioactive waste. The capacity of such barriers to avoid the disposed of radionuclides from entering the biosphere in the long-term depends on the service life of those materials. Thus, the performance assessment of structural materials under a series of environmental conditions prevailing at the environs of repositories is of significant interest. This study investigates the durability of cement paste, foreseen as backfill in a deep borehole for the disposal of disused sealed radioactive sources, as part of the development of the repository concept. The results are intended to contribute to the body of evidence in the safety case for the proposed disposal technology. This paper presents findings from X-Ray Diffraction (XRD) Analysis of cement paste exposed to varying temperatures and simulated groundwater after the samples had received the radiation dose expected to be accumulated until complete decay of the radioactive sources. The analysis serves to evaluate how such environmental factors influence the cement’s performance over time.