Influence of O/M ratio on sintering behavior of (U0.8, Pu0.2)O2±x

Assessing the oxygen stoichiometry during the sintering of (U, Pu)O 2 fuel

“…A significant release of O 2 and not UO 2 occurs during densification. It is well known that the local pO 2 will have a strong impact on the densification of the fuel sample [3,4], and the densification of PuO 2 is probably slowed down with such a high O 2 release above 900°C. Fig.…”

“…By comparing the measurements recorded during the sintering of pure PuO 2 and UO 2 , the following can be observed: 50-900°C: elimination of adsorbed moisture and organic species from the powder fabrication route, 300-900°C: reduction of UO 2+x into UO 2,00 , 900-1600°C: reduction of PuO 2 or (U, Pu)O 2 (solid solution formed at high temperature) into PuO 2Àx or (U, Pu)O 2Àx . In this temperature range, the release of O 2 leading to a significant increase in the local pO 2 likely induces a decrease of the temperature of densification and an increase of the densification rate as well [3,4].…”

“…The latter sets the nature and the concentration of point defects which govern diffusion mechanisms inside the material [2]. The oxygen partial pressure, pO 2 , of the sintering gas in equilibrium with MOX pellets needs to be precisely controlled; otherwise it may induce a large dispersion in the critical parameters for fuel manufacturing [2][3][4]. Among these parameters, the oxygento-metal ratio (O/M) after sintering defines many properties of the fuel in operation (thermal conductivity, mechanical properties, fuel-cladding interaction, etc.).…”

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

“…Several type of nuclear reactors and associated fuel are under consideration within the framework of the 4th generation international forum [1][2][3][4][5][6][7][8][9][10][11]. Sodium-cooled fast reactors (SFRs) are envisaged in France and an experimental prototype, ASTRID, is being currently under development [12].…”

Effect of oxygen‐to‐metal ratio on densification behavior in the sintering process of PuO2 pellets

“…It is important to control pellet density in the pellet production; sintering is one of the important processes available to control pellet density and to fabricate stable MOX pellets. Some studies on sintering behavior of oxide fuels have been reported [4][5][6][7][8][9]. Takeuchi et al [4,5] studied sintering behavior of MOX fuel in several atmospheres as a function of hydrogen partial pressure-tomoisture partial pressure (P H2 /P H2O ) ratio and they reported that sintering rate was affected by O/M ratio during the sintering process, and characteristics, such as density, dimensions and homogeneity of MOX pellets could be controlled by controlling the O/M ratio.…”