Determination of actinide local chemical environnement and valence state in Plutonium(IV) or Uranium(VI) gels with citric acid or glycine

The aim of this proposal is to investigate the valence state and the local chemical environment of uranium and plutonium gels obtained with reaction of actinide(s) nitrates with citric acid and glycine by X-ray Absorption techniques (EXAFS and HERFD-XANES). More specifically, EXAFS will be conducted in order to probe the Pu and U local environments. Moreover, HERDF-XANES on simple and mixed actinides gels will be used to determine oxidation state of U and Pu. These gels are used as precursors for Solution Combustion Synthesis of mixed actinides oxides. Indeed, gels preparation (glycine/uranium or citric acid/uranium ratio...) strongly affect actinide oxides characteristics after combustion. Our objective is to correlate differences observed in powders (oxidation state, residual carbon content) and to initial gel properties.