Calculated thermodynamic properties of GdCl3 in LiCl-KCl eutectic molten salt

The thermodynamic behaviors of lanthanides in molten salt are significant for the pyroprocessing of spent nuclear fuel. In this study, the ternary phase diagram of LiCl-KCl-GdCl3 system was assessed by the CALPHAD method using two-sublattice model. The liquidus surfaces were calculated and plotted from 720 K to 1000 K. The solubility of GdCl3 from 720 K to 850 K was determined from the phase diagram developed. The activity coefficient and apparent potential of GdCl3 with a concentration up to 3 mol% were also investigated. They both show a dependence on the concentration. From 0 to 3 mol%, the apparent potential increases by about 3% and the activity coefficient increases by about 50%.