Gas-bentonite interactions: Towards a better understanding of gas dynamics in Engineered Barrier Systems

Bentonite is a common backfill material used in Engineered Barrier Systems (EBS) for radioactive waste disposal. Its thermal, hydraulic, and chemical properties have been extensively studied. However, empirical evidence on the interactions with free gas phase present its pore space under conditions close to those prevailing deep geological repositories (i.e., exposure multiple species at temperature humidity of freshly backfilled EBS) scarce. This limits prediction/assessment evolution composition EBS. Here we outcome laboratory experiments targeting such gas-bentonite using two different types bentonite (Italian bentonite; Wyoming bentonite) being exposed atmospheric air sealed stainless-steel vessels. The results indicate that sorption can occur repository-like likely play significant role overall dynamics Drying both bentonites was shown partly re-activate their CO2 capacity during subsequent re-hydration phase. Furthermore, grinding resulted generation new pyrite surfaces significantly enhanced O2 removal from by oxidation. Our initial investigations call more systematic extensive series order quantitatively constrain processes involved interactions.