U/Th Particle Analyses

This proposal aims to investigate uranium (U) and thorium (Th) coordination environments using bulk EXAFS at the ROBL beamline (BM20). Samples come from two experiments. The first examines short-term (30-day) alteration of generation IV nuclear fuel particles in simulated lung fluids. Building on our recent study of UO₂ alteration, we use a suite of techniques to assess particle surface oxidation and secondary phase formation for advanced fuel in lung environments, informing health-risk assessment. The second investigates Th colloid formation during sorption to bentonite under conditions relevant to Finland’s Onkalo repository. This part is conducted as a continuation of previous successful beamtimes at ROBL studying radionuclide-bentonite interactions. We now aim to identify the formation mechanisms and stability of (intrinsic) Th colloids that control actinide mobility in bentonite-buffered systems.