Résumé
Anthropogenic activities have released significant amounts of plutonium in the environmentdue to the development of nuclear energy for industrial applications, space exploration andweapon production.|1,2] Both pseudo- and intrinsic plutonium colloids have been described aspotential vectors for the migration of actinides in the environment. Whereas pseudo-colloidsdeal with natural inorganic colloids on which Pu has been incorporated or adsorbed, intrinsiccolloids are related to the propensity of tetravalent Pu to hydrolyze and form its own colloid.[1-3] Predicting the behavior and reactivity of such species in the geosphere is a challenging topicrequiring their thorough characterization in order to provide a better knowledge of their localstructure, morphology, size and interfacial properties. X-ray based techniques appearparticularly relevant to probe the multi-scale properties of Pu colloids. The recent developmentof an analytical bench devoted to the quasi-simultaneous analysis of radioactive samples bysmall-angle X-ray scattering (SAXS) and X-ray absorption spectroscopy (XAS) on the MARSbeamline of the synchrotron SOLEIL allowed us to screen intrinsic Pu(IV) colloids (Fig. 1).Two kinds of stable colloidal suspensions prepared by conventional hydrolysis and sonicationof PuO2 powder in pure water (20 kHz, 20 °C, Ar/10%CO atmosphere) were investigated.[4,5]The non-intrusive synchrotron SAXS/XAS approach described in this work provides in-situinformation, over a large sample volume and directly in the native environment. The approachappears ideal for Pu colloidal systems and demonstrates that the preparation conditionsstrongly influence the multi-scale properties of intrinsic Pu(IV) colloids