Thermodynamic investigations of the NaI-CsI, KI-CsI, and NaF-CsI pseudo-binary systems

[Display omitted] •Improved experimental results and thermodynamic models were obtained for the NaI-CsI and KI-CsI pseudo-binary systems using DSC measurements.•New reciprocal salts measurements of the NaF-CsI system.•Experimental sensitivity analyses for sample mass and heating rates, determined that 50 mg and 5 °C/min are reasonable values.•Contribution to the Joint Research Center Molten Salt Database (JRCMSD). The present study describes the thermodynamic assessment of three pseudo-binary systems relevant to CsI solubility in molten iodide salts: KI-CsI, NaI-CsI, and NaF-CsI. The motivation for this study was to corroborate a single previously reported data set of the NaI-CsI system, resolve inconsistencies reported by two different data-sets of the KI-CsI system, and generate new experimental data on the NaF-CsI system. Equilibrium data for all systems were obtained using Differential Scanning Calorimetry. Thermodynamic treatments of the three pseudo-binary systems were revised using the CALPHAD method with the thermodynamic software FactSage and Thermochimica. Both experimental and computational investigations provide increased confidence in the thermochemical behaviour of CsI in Molten Salt Reactor nuclear systems.