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

Abstract

A methodology to estimate the heat of mixing (ΔmixH) for salt liquids in unexplored AkCl–AnClx/LnClx (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 ΔmixH prior to performing the estimation, which avoids the intrinsic ambiguity of that approach. This semiempirical method has computationally reproduced the behavior of NaCl–UCl3 and KCl–UCl3 systems, providing ΔmixH 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–UCl3 and AkCl–PuCl3 systems, the results from which have facilitated the accurate thermodynamic modeling of these and other AkCl–AnCl3/LnCl3 systems. The resultant assessed Gibbs energy functions and models have been incorporated in the Molten Salt Thermal Properties Database–Thermochemical (MSTDB-TC).