Phase Equilibria for the Ternary Fused‐Salt System NaF–BeF₂–UF₄

Abstract

The phase equilibrium diagram for the ternary fused‐salt system NaF–BeF2–UF4 was based on evidence from differential thermal analysis, polarized light microscopy, and X‐ray examination of samples obtained from thermal‐gradient quenching studies and from high‐temperature filtration experiments. All the stable compounds in the binary systems NaF–BeF2 and NaF–UF4 displayed primary‐phase fields in the ternary system, including a new subsolidus compound which was observed and tentatively assigned the formula NaF · 4UF4. No ternary compounds or solid solutions were observed. The following three eutectics were found in the ternary system: (1) 72.5 NaF, 17.0 BeF2, and 0.5 mole % UF4 at 486°C, (2) 56.0 NaF, 43.5 BeF2, and 10.5 mole % UF4 at 339°C, and (3) 43.5 NaF, 56.0 BeF2, and 0.5 mole % UF4 at 345°C.

HT-NMR Studies of the Be–F Coordination Structure in FNaBe and FLiBe Mixed Salts

“…As a type of kindred element, NaF possesses highly similar physical properties to LiF, which makes NaF/BeF 2 (FNaBe) mixed salts a promising candidate to replace FLiBe in MSR applications. , Initially, the physical properties of FNaBe melts were studied to explore the feasibility of applying them as a coolant and fuel salt carrier, with a phase diagram as the main subject of research . The phase diagrams of NaF-BeF 2 and NaF-BeF 2 –UF 4 were determined to confirm the applicability of the ternary face system as a liquid medium for transporting nuclear fuel in nuclear reactors . With the development of computational chemistry and numerical simulation methods, many computational methods have been developed to investigate the thermal properties of molten salts, including the soft-sphere equation of state method and first-principles molecular dynamics (FPMD) simulations. , In addition, the thermal properties of FNaBe, such as thermal conductivity, viscosity, density, and phase transition behavior, were predicted by theoretical calculations .…”

“… 11 The phase diagrams of NaF-BeF 2 and NaF-BeF 2 –UF 4 were determined to confirm the applicability of the ternary face system as a liquid medium for transporting nuclear fuel in nuclear reactors. 12 With the development of computational chemistry and numerical simulation methods, many computational methods have been developed to investigate the thermal properties of molten salts, including the soft-sphere equation of state method and first-principles molecular dynamics (FPMD) simulations. 7 , 13 In addition, the thermal properties of FNaBe, such as thermal conductivity, viscosity, density, and phase transition behavior, were predicted by theoretical calculations.…”