Direct Calculation of Concentration-Dependent Activity Coefficient of UCl3 in Molten LiCl-KCl

It is believed that the thermodynamic properties, such as activity coefficient of UCl3 in molten LiCl-KCl, are concentration-dependent. However, most of the available experimental data now are limited to the extreme dilution cases. In the present study, thermodynamic integration (TI) method was applied to calculate the Gibbs energy of supercooled UCl3 and UCl3 in LiCl-KCl molten salt with different concentrations of UCl3 and then calculate the activity coefficient directly for different concentrations at a given temperature of 723 K. The calculated activity coefficients at low concentration cases were compared with available experimental measurements, and the comparison indicates the calculation results agree well with the literature. Most importantly, the present calculation shows that the activity coefficient of UCl3 in the molten salt is indeed a function of its concentration and increases with the mole fraction. (c) The Author(s) 2015. Published by ECS. All rights reserved.