Thermodynamic evaluation of the (LiF+NaF+BeF2+PuF3) system: An actinide burner fuel

Thermodynamic assessment of the LiF–NaF–ThF4–UF4 system

“…In order to create such a database we first assess the binary sub-systems based on the available experimental data and afterwards the higher order systems are extrapolated according to the Toop mathematical formalism. This approach was shown as a very strong tool of predicting the fuel behaviour as demonstrated in previous studies [2][3][4]. Furthermore once the thermodynamic database is developed properties such as melting temperature, vapour pressure or solubility of actinide fluorides in the fuel matrix can be calculated.…”

“…The LiF-ThF 4 -UF 4 phase diagram has been investigated in detail by Weaver et al [21] and has been thermodynamically assessed by van der Meer et al [22] using a polynomial formalism for the description of both liquid and solid solutions. It contains three invariant equilibria, two eutectics and one quasi-peritectic.…”

Thermodynamic evaluation and optimization of the (NaF+AlF3+CaF2+BeF2+Al2O3+BeO) system

“…A thermodynamic assessment of the (NaF + BeF 2 ) system was previously made by Benes and Konings [44], where the Modified Quasichemical Model was used for the liquid phase with only one composition of maximum short-range ordering, close to the composition Na 3 Be 2 F 7 . This previous assessment was based solely on the phase diagram measurements of Roy et al [9] and the vapour pressure measurements of Sense and Stone [14] and Fukuda et al [15].…”

Developing Practical Models of Complex Salts for Molten Salt Reactors

“…The issue of variable coordination numbers is illustrated in a comparison of analyses performed with and without that assumption. An analysis of fluoride fuel salt for MSR applications by Benes and Konings [24] reasonably well reproduces the experimental phase diagram for the pseudo-binary NaF-BeF2 using measurements confined to less than 60 mol% BeF2. Their MQM representation utilized single endmembers for the fluorides and thus the fixed coordination numbers…”

“…On the plot are also indicated the RT ln(pF2) values for equilibria between the major Hastelloy-N elements (71Ni-16Mo-7Cr-4Fe mass) and their fluorides (except for molybdenum, which has values that are significantly more positive). Accurate calculations also require consideration of the activities of the metals in the alloy, i.e., alloy solid solutions or secondary phases, and thus models for the alloy phases (SGTE 2020 Alloy Database) [24] were equilibrated with the salt in calculating the indicated equilibrium reactions of Figure 4. The metal-fluoride equilibria thus provide threshold values, where more positive system RT ln(pF2) values will cause the fluoride of the metal to be more stable and thus potentially corrosion of the alloy.…”