Ambiguity in the crystal chemistry and dissolution kinetics of doped uranium dioxide nuclear fuels

Nuclear fuel, composed of UO2, has a complex chemistry and fuel manufacturers are increasingly interested in adding dopants that improve the performance within a nuclear reactor. The introduction of these dopants into the UO2 system can intrinsically alter the crystal chemistry and local speciation of the system, which in turn influences the oxidation behaviour. This may have negative consequences on the aqueous corrosion of the U-O system and therefore influence the safety of spent nuclear fuel in a geological disposal facility. In this proposal, we aim to understand the influence of metal dopants (Al, Cr, Ti) on the local structure, speciation and radiolytic dissolution of [001]-oriented UO2 single crystal thin films.We will systematically understand the local structure and speciation of U and metal dopants as a function of dopant type and concentration (HERFD-XANES), and we will quantify the dissolution of these materials through in-situ corrosion experiments performed using XRD.