In situ dehydration of the uranium mineral studtite: a variable temperature U M4-edge XAS and XES study.

The dehydration of studtite [UO2(O2)(H2O)2].2H2O is complex but goes through an X-Ray amorphous phase, whose structure is unknown, but possibly U but Possibly U2O7. Importantly it has been the cause of accidents in waste storage facilities. This project aims to explore the dehydration in an in-situ experiment at the U M4-edge by measuring the HERFD-XAS at intermediate temperature points from room temperature to 800 oC where the transition goes [UO2(O2)(H2O)2] to U2O7 to UO3, but no in-situ experiments have been conducted to look for intermediate phases. In addition at structural changes we will measure the v2C XES spectra for a full description on the electronic structure. This work will give more detailed information on the decomposition and structural phases observed in this important material and add to safety cases for both short and long term storage of uranium in waste nuclear fuel cycles.