High temperature X-ray diffraction study of the kinetics of phase separation in hypostoichiometric uranium–plutonium mixed oxides

Room-temperature oxidation of hypostoichiometric uranium–plutonium mixed oxides U1−yPuyO2−x – A depth-selective approach

“…Pawley refinement [36] and phase fractions by the Rietveld analysis [37]) are reported elsewhere [12,38].…”

“…Thus, determining the oxygen stoichiometry is of main interest for various applications, including production of nuclear oxide fuels [2]. In the UO 2 -PuO 2 -Pu 2 O 3 sub-system, U 1-y Pu y O 2-x mixed oxides with high plutonium content (> 0.20) are multiphasic at room temperature [3][4][5][6][7][8][9][10][11][12][13]. The miscibility gap is composed of two f.c.c.…”

“…phase in the higher plutonium content range [5][6][7][8][9]. The two phases constituting the hypostoichiometric mixed oxides exhibit different oxygen content and are then called "high-oxygen" and "low-oxygen" phases, respectively [12,13]. During its lifetime within the nuclear cycle, the fresh uranium-plutonium mixed oxide U 1-y Pu y O 2-x is subjected to various atmospheres at room temperature (glove box atmosphere, air, …) for several timespans (e.g.…”

Influence of the oxygen potential on the sintering of UO2–45% PuO2

“…Sodium-cooled fast reactors (SFRs) are envisaged in France and an experimental prototype, ASTRID, is being currently under development [12]. Mixed uranium-plutonium oxide (MOX) fuel with plutonium content close to 30% is considered as candidate fuel for such reactor, and the research work regarding its fabrication is under progress [13][14][15][16][17].…”

“…However, for the other studied oxygen potentials, only one phase corresponding to the U 0.55 Pu 0.45 O 2−x solid solution is observed, which is in contradiction with the U Pu O phase diagram. Recently, Vauchy et al[17,32] has shown that during cooling down the (U, Pu)O 2−x phase can be oxidized due to the gas mixture-open system. This oxidation precludes the phase separation indicated in the phase diagram.…”