Thermodynamic evaluation of LiCl-KCl-PuCl3 system

The present study focuses on developing the phase diagram of LiCl-KCl-PuCl3 system based on the CALPHAD (CALculation of PHase Diagram) method. Sub-binary systems of LiCl-KCl, LiCl-PuCl3, and KCl-PuCl3 were developed first by optimizing the Gibbs energy parameters according to the experimental data from literature using the two-sublattice model. Then the enthalpy of mixing of the LiCl-KCl-PuCl3 system was estimated, to explore the ternary interactions, using an empirical correlation derived from the surrounded-ion model for the asymmetric salt system due to the scarcity of available data for the ternary system. Based on the phase diagram developed, the solubility of PuCl3 in the eutectic LiCl-KCl melt at different temperatures was obtained, as well as the Gibbs energy of formation of PuCl3 in the salt as a function of PuCl3 concentration. The present study extends the experimental data for dilutions to concentrated solutions for which no experimental data have been well reported. (C) 2016 Elsevier B.V. All rights reserved.