Correlational Approach to Predict the Enthalpy of Mixing for Chloride Melt Systems

[Image: see text] A methodology to estimate the heat of mixing (Δ(mix)H) for salt liquids in unexplored AkCl–AnCl(x)/LnCl(x) (Ak = alkali, An = actinide, Ln = lanthanide) systems is developed. It improves upon previous empirical approaches by eliminating the need for arbitrarily choosing the required composition at maximum short-range ordering, the minimum Δ(mix)H prior to performing the estimation, which avoids the intrinsic ambiguity of that approach. This semiempirical method has computationally reproduced the behavior of NaCl–UCl(3) and KCl–UCl(3) systems, providing Δ(mix)H values that agree well with the reported measurements within a propagated two standard deviations (2σ). The capability of the approach is demonstrated in its application to the entirety of the AkCl–UCl(3) and AkCl–PuCl(3) systems, the results from which have facilitated the accurate thermodynamic modeling of these and other AkCl–AnCl(3)/LnCl(3) systems. The resultant assessed Gibbs energy functions and models have been incorporated in the Molten Salt Thermal Properties Database–Thermochemical (MSTDB-TC).