Reactive sintering of U1−yAmyO2±x in overstoichiometric conditions

In the framework of Partitioning & Transmutation (P&T), U1−yAmyO2±x materials are promising fuels for Am recycling. In this context, these materials were fabricated in the ATALANTE facility by a process which consists of pelletizing and reactive sintering. Since it was effective in studies conducted on UO2+x, sintering in overstoichiometric conditions was investigated. In this work, three Am contents (10, 20 and 30%) and four temperatures (from 1000 to 1300 °C) were studied. It was shown that low-density and multiphasic compounds were obtained. Moreover, XRD and XAFS analyses pointed out that the total reduction of Am(+IV) to Am(+III) and solid solution formation occur during sintering at temperatures inferior to 1300 °C. Although previous studies on UO2+x showed that high oxygen potential enhanced the diffusion process, this work proved that this effect is clearly modified by the presence of Am. Finally, sintering in overstoichiometric conditions is not yet suitable for Am-bearing fuel fabrication.