On the melting behaviour of uranium/plutonium mixed dioxides with high-Pu content: A laser heating study

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).…”

Examination of nanosecond laser melting thresholds in refractory metals by shear wave acoustics

“…[17][18][19] Time resolved spectral pyrometry was used to measure melting points of stainless steel and platinum using nanosecond laser heating. 20 There has also been intense research devoted to measure melting points of refractory materials using laser pulses on the scale of milliseconds [21][22][23] and microseconds. 24 In this work we have introduced automated control of laser pulse energy-induced melting to improve measurement accuracy by studying dynamic thermomechanical properties in thermoelastic regime, at and above melting in several refractory metals such as (niobium, molybdenum, tantalum and tungsten) with various bulk shearing behavior, by actually measuring nanosecond laser melting thresholds in these metals.…”