Key Phase Diagram Experiments and Thermodynamic Modeling of the NaCl–KCl–UCl 3 System for Molten Salt Reactor Applications

For the design of a molten salt system for a molten salt reactor (MSR), accurate thermodynamic information for multicomponent salt systems is essential. In the present study, thermodynamic modeling of the NaCl–UCl 3 , KCl–UCl 3 , and NaCl–KCl–UCl 3 systems were performed based on the critical evaluation of available phase diagram and thermodynamic property data in literature. In order to improve the accuracy of thermodynamic modeling of the ternary NaCl–KCl–UCl 3 system, the phase transitions of key ternary samples were determined using innovative electrical conductivity measurements. Based on the present modeling results, the exact ternary eutectic composition of the NaCl–KCl–UCl 3 system (0.433NaCl–0.217KCl–0.350UCl 3 ), which is critical for the MSR salt design, was experimentally determined for the first time. The resultant thermodynamic database was applied to the calculations of phase diagrams and thermodynamic properties relevant to MSR operations.