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

Area of Science:

• Materials Science
• Physical Chemistry
• Nuclear Engineering

Background:

• Accurate thermodynamic data is crucial for molten salt systems, particularly those involving actinides.
• Previous empirical methods for estimating heat of mixing (ΔmixH) in salt liquids had limitations regarding composition selection.

Purpose of the Study:

• Develop a robust methodology for estimating the heat of mixing (ΔmixH) in unexplored alkali chloride-actinide/lanthanide chloride (AkCl-AnCl/LnCl) salt systems.
• Improve upon existing empirical approaches by removing arbitrary composition choices and intrinsic ambiguities.

Main Methods:

• Developed a novel semiempirical method for estimating heat of mixing in complex salt mixtures.
• Validated the method by computationally reproducing heat of mixing for NaCl-UCl3 and KCl-UCl3 systems.

Main Results:

• The semiempirical method accurately reproduced heat of mixing (ΔmixH) for tested systems, aligning with experimental data within 2σ.
• Applied the methodology to the full range of AkCl-UCl3 and AkCl-PuCl3 systems.
• Generated accurate thermodynamic models and Gibbs energy functions for these systems.

Conclusions:

• The developed methodology provides a reliable way to estimate heat of mixing for unexplored molten salt systems.
• The findings facilitate accurate thermodynamic modeling of AkCl-AnCl3/LnCl3 systems.
• The assessed thermodynamic data has been integrated into the Molten Salt Thermal Properties Database-Thermochemical (MSTDB-TC).