In-situ X-ray fluorescence to investigate iodide diffusion in opalinus clay: Demonstration of a novel experimental approach.

During the last two decades, the Mont Terri rock laboratory has hosted an extensive experimental research campaign focusing on improving our understanding of radionuclide transport within Opalinus Clay. The latest diffusion experiment, the Diffusion and Retention experiment B (DR-B) has been designed based on an entirely different concept compared to all predecessor experiments. With its novel experimental methodology, which uses in-situ X-ray fluorescence (XRF) to monitor the progress of an iodide plume within the Opalinus Clay, this experiment enables large-scale and long-term data acquisition and provides an alternative method for the validation of previously acquired radionuclide transport parameters.

Comparison of models to evaluate microbial sulphide generation and transport in the near field of a SF/HLW repository in Opalinus Clay.

In a deep geological repository for radioactive waste in the Opalinus Clay, disposal canisters may be corroded due to sulphide produced by sulphate reducing bacteria (SRB). This paper presents two computational models, a reactive transport model (RTM) and a simplified semi-analytical model (SM), to evaluate the potential of SRB to generate elevated sulphide concentrations, to assess sulphide fluxes to the canister and, in a simplified manner, the resulting canister corrosion. Calculations performed in the context of the repository's safety assessment based on a shared conceptual model reveal that the two computational models are complementary.

Pore water colloid properties in argillaceous sedimentary rocks.

The focus of this work is to evaluate the colloid nature, concentration and size distribution in the pore water of Opalinus Clay and other sedimentary host rocks identified for a potential radioactive waste repository in Switzerland. Because colloids could not be measured in representative undisturbed porewater of these host rocks, predictive modelling based on data from field and laboratory studies is applied. This approach allowed estimating the nature, concentration and size distributions of the colloids in the pore water of these host rocks.

KAg11(VO4)4 as a candidate p-type transparent conducting oxide.

For a material to be a good p-type transparent conducting oxide (TCO), it must simultaneously satisfy several design principles regarding its bulk and defect phase thermochemistry, its optical absorption spectrum, and its electric transport properties. Recently, we predicted Ag3VO4 to be p-type but with low conductivity and an optical band gap not large enough for transparency. To improve on the transport and optical properties of Ag3VO4, we searched an extended material space including quaternary compounds based on Ag, V, O, and an additional atom for a new candidate p-type TCO.