Radiation enhanced diffusion processes in UO₂and (U,Pu)O₂

Cation interdiffusion in uranium–plutonium mixed oxide fuels: Where are we now?

“…Even at room-temperature, this crystal structure can accommodate large deviations from oxygen stoichiometry (O/An = 2) as evidenced in the pure poles UO 2+x (Geønvold and Haraldsen, 1948), PuO 2−x (Gardner et al, 1965), AmO 2−x (Chikalla and Eyring, 1968), CmO 2−x (Mosley, 1972), BkO 2−x (Baybarz, 1968), and CfO 2−x (Baybarz et al, 1972) as well as in the respective solid solutions, the most studied being U 1−y PuyO 2±x Markin and Street, 1967), U 1−y Am y O 2±x (Bartscher and Sari, 1983), and Pu 1−y Am y O 2−x (Vauchy et al, 2017). These deviations from stoichiometry and irradiation defects both induce severe lattice defects and can also enhance atomic diffusion (Kilner et al, 1981;Matzke, 1983a;Ferry et al, 2005;Smirnov and Elmanov, 2016). Due to the large mass of the actinide atoms, cationic vacancies and/or interstitials are unprobeable; thus, only the anion sub-lattice (oxygen) supports the defects Atlas et al, 1966;Matzke and Sørensen, 1981;Matzke, 1987), namely, oxygen vacancies (V ) pairs in the AnO 2 region (Cristea et al, 2007;Kato et al, 2017a).…”