Description

The Molten Salt Thermal Properties Database-Thermochemical (MSTDB-TC) Ver. 4.0, is a publicly available compendium of thermodynamic models and values for fluoride, chloride, and some iodide components and related systems of interest for molten salt reactor technology. These include fuel or coolant salts, consequential fission product and transuranic elements, and likely corrosion product elements such as iron, nickel and chromium. Phases include gas/vapor, liquids (i.e., molten salts and their components), solid solutions, and stoichiometric compounds. The database has been developed using FactSage® commercial software and is provided in the ChemSage .dat format. It is compatible with the open-source equilibrium codes Thermochimica and PyCalphad. The database is wholly internally consistent, but not necessarily consistent with other databases and caution should be exercised when using it with othersources. In addition, tomaintain consistency Ver. 4.0 should not be used in combination with earlier MSTDB-TC versions as some systems have been revised for Ver. 4.0.

The recent versions of the database include multiple reciprocal salt systems, i.e., in addition to multiple cations some systems have more than one anion. Note that reciprocal systems are represented graphically in the figure below to allow the user to best understand the relationships in these systems. The square represents all four species of a system with two cations and two anions, referred to as a reciprocal salts, with the pairs connected by the diagonals that form ternary reciprocal systems and are allowed to exchange both anions and cations. Additional information regarding reciprocal salts can be found in Blander, et al.[1]

[1] M. Blander. “The topology of phase diagrams of ternary molten salt systems”, Chemical Geology 3 (1968) 33–58.
https://doi.org/10.1016/0009-2541(68)90012-0.

Caution

• It is possible to perform thermodynamic equilibrium calculations with FactSage, Thermochimica, or other software using MSTDB-TC for salt melts that contain multiple cations/anions where major components of the salt mixture may not have been included in the system assessment. While calculations may be possible, the results may not be fully accurate as all possible interactions will not have been considered. Low concentration components in a mixture will be less affected, although caution is still urged.  The user is advised to check the listing of MSTDB-TC systems to be assured that their system of interest has been included.
• While accurate heat capacity values are used for components in system assessments, heat capacity values obtained from an equilibrium calculation for a mixture may not be accurate as extended temperature-dependent terms for the component heat capacities may not have been utilized in the system optimization. When looking to use heat capacity values for higher order systems caution should be exercised and references for the MSTDB-TC system assessment should be reviewed. In general, heat capacity values for melt solutions are best obtained from MSTDB-TP, assuming they are available for a particular higher order system in question.