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|Title:||Experimental Determination of the Thermal Conductivity of Liquid UO2 Near the Melting Point|
|Authors:||SHEINDLIN Michael; STAICU DRAGOS; RONCHI C.; GAME-ARNAUD L.; REMY B.; DEGIOVANNI A.|
|Citation:||JOURNAL OF APPLIED PHYSICS vol. 101 p. 093508|
|Publisher:||AMER INST PHYSICS|
|Type:||Articles in periodicals and books|
|Abstract:||The article gives an account of measurements of the thermal conductivity of liquid UO2. The sample was heated up to above the melting point by a laser pulse of a controlled shape, and the produced thermogram of temperature history was measured by a fast and accurate pyrometer with a time resolution of 10 s. The experiment shows that the rate of temperature increase during the ascending part of the pulse changes moderately across the melting point. Due to the high power input, this effect cannot be explained in terms of the sole intake of latent heat of fusion. By solving the related heat transfer equation with a 2D-axisymmetric numerical model, it is demonstrated that this feature depends principally on heat conduction in the sample, and proves that the thermal conductivities of solid and liquid are not very different. A theoretical sensitivity study assessing the influence of the liquid thermal conductivity on the pulse temperature evolution showed that the conductivity of the liquid can be deduced from the fitting of the thermograms with a numerical precision of the order of 1%. The analysis reveals that the thermal conductivity is weakly correlated with the effective heat losses during the pulse and to the melting enthalpy, so that the uncertainty in its evaluation by fitting the experimental thermograms with model predictions is satisfactory. The value of the thermal conductivity of liquid UO2 near the melting point resulted to be 2.6±0.35 W m-1 K-1, where the magnitude of the uncertainty is much lower than the scatter of the previously published, discordant measurements.|
|JRC Directorate:||Nuclear Safety and Security|
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