Reassessing the melting temperature of PuO2

Melting behaviour of americium-doped uranium dioxide

“…Given the limited amount and the high radioactivity of the investigated material, this dataset size was considered to be satisfactory, in that it permitted to obtain significant average values and standard deviations for each composition. The laser pulses lead to maximum temperatures between 3350 K and 3550 K. These temperatures compared with the expected values of the solid/liquid phase transitions for the pure dioxides [21][22][23][24][25]27,29], can be considered to be high enough to melt a sufficient amount of material to obtain a consistent thermal analysis during the cooling stage of the experiments.…”

“…The melting behaviour of the current mixed (uranium + americium) dioxides was studied by laser heating and fast multi-channel pyrometry, an experimental method developed at JRC-ITU [21][22][23][24][25][26]. Details of the laser-heating setup used in this research have been reported in previous publications [21][22][23][24][25][26], although the technique has been partially modified in the present work.…”

“…Details of the laser-heating setup used in this research have been reported in previous publications [21][22][23][24][25][26], although the technique has been partially modified in the present work. During the laser shots, a mixed oxide disk was held in a sealed autoclave under a controlled atmosphere of pressurized argon in which the absolute pressure of oxygen was checked and was lower than 10 Pa.…”

“…The method used for the melting experiments is based on laser heating and a self-crucible approach in order to avoid sample-crucible interactions during the measurements. It was recently applied to UO 2 [21], PuO 2 [22,23], U 1Àx Pu x O 2 [24,25] and MA-doped U 1Àx Pu x O 2 samples [26], and proved to give more accurate values than those previously obtained through more traditional thermal analysis methods [24,25,27]. The samples were also characterised after melting using powder X-ray Diffraction (XRD) and X-ray Absorption Spectroscopy (XAS).…”

High temperature phase transition of mixed (PuO 2 + ThO 2 ) investigated by laser melting

“…PuO 2 is therefore possibly easier to be reduced to a 3+ state [5]. (iv) Finally, only two basic assessments exist for the high temperature region [6,7] which also have to be updated with the newer results for PuO 2 [8].…”