Raman study of the surface oxidation in (U, Pu)O2 as a function of Pu content

J. Miren Elorrieta (1) , D. Manara (2) , L. Bonales Jimenez (1) , Jf. Vigier (2) , O. Dieste (2) , M. Naji (2) , Rc. Belin (3) , Vg. Baonza (4) , Rjm. Konings (2) , J. Cobos (1)

1 CIEMAT - Centro de Investigaciones Energéticas Medioambientales y Tecnológicas [Madrid]
2 JRC - European Commission - Joint Research Centre [Karlsruhe]
3 CEA-DES (ex-DEN) - CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire)
4 UCM - Universidad Complutense de Madrid = Complutense University of Madrid [Madrid]

This work presents a systematic Raman study of the matrix oxidation in a variety of (U1-y, Puy)O2 compositions (0 ≤ y ≤ 0.46) at different temperatures, between 250 DC and 400 DC. Our results indicate that the increase in Pu content hinders the oxidation process of the dioxide matrix. Further oxidation of the uranium-plutonium mixed dioxides in air starts between 250 DC and 310 DC, on a time scale of several hours. M4O9 seems to be the most stable intermediate phase formed upon oxidation of all the investigated mixed oxides, before final oxidation to M3O8. In addition, X-ray diffraction measurements and SEM images confirm the trend observed by Raman spectroscopy, i.e. Pu stabilises the fcc structure of the dioxide.

Keywords: Interim storage; Nuclear waste; Uranium-plutonium mixed oxides; Raman spectroscopy; Oxidation

Domains: Nuclear Experiment [nucl-ex]; Nuclear Theory [nucl-th]

J. Miren Elorrieta, D. Manara, L. Bonales Jimenez, Jf. Vigier, O. Dieste, et al.. Raman study of the surface oxidation in (U, Pu)O2 as a function of Pu content. Journal of Nuclear Materials, 2017, 495, ⟨10.1016/j.jnucmat.2017.08.043⟩. ⟨cea-02415667⟩