The aim of this mobility event was to study the coordination environment of Sr sorbed to altered bentonite materials for potential use as a buffer material in high activity nuclear waste disposal scenarios using Sr K-edge Extended X-ray Absorption Fine Structure (EXAFS) spectroscopy. Here, we measured 6 samples where Sr has been sorbed to untreated and heat-treated (150 °C, for up to 36 months) bentonites at two pH regimes (8 and 13). The project is part of the EURAD-funded HITEC work package which seeks to improve Thermal, Hydrological and Mechanical (THM) understanding of clay-based materials exposed to elevated temperatures (>100 °C) for extended timescales. As well as studying the physicochemical changes to the material, we wish to provide a quantitative and mechanistic description of the effects of elevated temperature on bentonite / radionuclide interactions via the use of combined Sr sorption isotherm experiments and EXAFS analyses.
The analysis of results is still ongoing
