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On the present state of investigation of thermodynamic properties of solid and liquid UO2+x

“…4 A theoretical study addressing this aspect [19] gave predictions that are in agreement with the observed behaviour of C p (T).…”

“…These data were obtained by direct measurements of C p under quasi-stationary conditions, i.e., not from cooling rate measurements. The technique used is an extension of the laser-flash method for simultaneous measurement of thermal diffusivity and heat capacity, and was successfully tested with graphite and zirconia at very high temperatures [4] showing a good agreement with drop calorimetry results. Experimental results [3] indicate that C p in solid UO 2 monotonically increases at temperatures higher than 2670 K. This provides a selection criterion for a proper fitting function of the enthalpy vs. temperature data.…”

“…The recent analysis of Fink included the C p measurements by Ronchi et al [4,5]. In this work the heat capacity of liquid UO 2 was measured up to 8000 K from the analysis of the cooling curve of small spherical samples heated, under high hydrostatic pressure conditions, by four similar, tetrahedrally-oriented laser beams.…”

“…An observed pre-melting k-transition leads to a steep increase of the anion defect concentration at a temperature of approximately 2670 K. At higher temperatures, though saturation of the FP concentration is expected, a further increase in C p with temperature is still observed, whereby, due to the occurrence of the k-transition, direct calorimetric measurements above 2700 K are less precise [3][4][5].…”

Thermophysical characterization of ZrN and (Zr,Pu)N

“…Thermal diffusivity measurements were carried out using a laserflash apparatus (LAF.I) developed in ITU [44,45]. The device is placed in a Pb-shielded glove box equipped with remote manipulators, and is designed to perform measurements on irradiated fuel samples up to very high burnup.…”