Thermodynamic measurements and assessments for LiCl-NaCl-KCl-UCl3 systems

Thermodynamic Assessment of CrCl2 with NaCl–KCl–MgCl2–UCl3–UCl4 for Molten Chloride Reactor Corrosion Modeling

“…The solution models of the NaCl–KCl system were previously assessed and are compatible with a large number of systems currently in MSTDB-TC . However, our earlier thermodynamic assessment of the LiCl–NaCl–KCl–UCl 3 pseudo-quaternary system reported the NaCl–KCl solid solution as requiring reassessment due to being overly stable in the pseudo-ternary systems with UCl 3 . We have here found the same to be true for the NaCl–KCl–UCl 4 system.…”

“…During the measurements, a high-purity argon furnace tube (70 mL min –1 ) and protective gas (20 mL min –1 ) purges were used along with a tantalum ring getter to minimize crucible oxidation. The DSC was heated to 1773 K and held for 15 min after which temperature calibrations under heating and cooling were conducted following the zero K min –1 extrapolation procedure of Della Gatta et al The calibration incorporates a unique and reliable method of uncertainty quantification that was previously described …”

“…The DSC was heated to 1773 K and held for 15 min after which temperature calibrations under heating and cooling were conducted following the zero K min −1 extrapolation procedure of Della Gatta et al 28 The calibration incorporates a unique and reliable method of uncertainty quantification that was previously described. 6 The purity of MgCl 2 is estimated to be 0.99 ± 0.01, and that of CrCl 2 is estimated to be 0.98 ± 0.02 on a mole fraction basis from the powder XRD analysis and the characteristic shape of the DSC scans. DSC determined the melting points (T m ) of the pure salts as 986.8 ± 2.0 and 1090.5 ± 2.1 K, which have reported values of 987.2 29 and 1097.2 K, 29 respectively (expanded uncertainty U(T), 27 95% confidence approximately 2σ).…”

“…The characterization of the UCl 3 material was previously reported. 6 The XRD pattern and DSC scans of MgCl 2 and CrCl 2 are provided in the Supporting Information (Figures S1−S4).…”

“…The first nearest-neighbor (FNN) to SNN correlation factor, ζ A/Cl , is given by eq as defined by Wang et al based on the endmember cation (Z A/X A ) and anion (Z A/X X ) coordination numbers. The values for the alkali chlorides with MgCl 2 and UCl 3 were determined previously, with eqs and containing the values for the divalent chlorides and UCl 4 , respectively, as determined from Z A/X A = 6 and Z A/X X = Z A/X A / n , where n is the cation valence. ζ normalA / normalX = 2 normalZ normalA / normalX normalA normalZ normalA / normalX normalX normalZ normalA / normalX normalA + 0.25em normalZ normalA / normalX normalX 0.25em ζ Mg / Cl = ζ Cr / Cl = 4 0.25em ζ normalU IV / Cl = 2.4 …”