| Forecast of geometrical structure for T-x-y-z diagram Li,Na,Th,U||F Vasily Lutsyk1; Anna Zelenaya1; Maria Parfenova2; Marina Lamueva3; 1INSTITUTE OF PHYSICAL MATERIALS SCIENCE SB RAS, Ulan-Ude, Russian Federation; 2TOMSK STATE UNIVERSITY OF CONTROL SYSTEMS AND RADIO-ELECTRONICS, Tomsk, Russian Federation; 3INSTITUTE OF PHYSICAL MATERIALS SCIENCE, Ulan-Ude, Russian Federation; PAPER: 173/Molten/Regular (Oral) SCHEDULED: 14:50/Fri. 25 Oct. 2019/Ambrosia A (77/RF) ABSTRACT: Geometric structure of four T-x-y diagrams, forming the T-x-y-z diagram of the quaternary system Li,Na,Th,U||F have been thoroughly analyzed, and 3D models of 4 space diagrams have been assembled. On the basis of data for the structure of the bounding binary and ternary systems, a scheme of mono and invariant states for the quaternary system has been formed. This scheme is the basis for the topological forecast of the geometrical structure of the Т-х-y-z diagram for LiF-NaF-ThF<sub>4</sub> -UF<sub>4</sub> (А-B-C-D) system. Nineteen binary compounds R(J) and 30 invariant transformations (2 peritectic, 20 quasiperitectic and 8 eutectic ones) are characterized this quaternary diagram. It is expected that within the quaternary system, 10 invariant reactions involving the melt (6 of quasiperitectic type and 4 of peritectic type) should run. The Т-х-y-z diagram will be formed by 17 hypersurfaces of liquidus. Seven of them correspond to the primary crystallization of lithium and sodium fluorides (A and B) and solid solutions С(D), R2(R11), R4(R12), R7(R15), R8(R16). Ten of them correspond to the primary crystallization of compounds R1, R3, R5, R6, R9, R10, R13, R14, R17, R18. Compound R10 on the edge LiF-UF4 (A-D) has, in both ternary adjoining systems, LiF-NaF-UF4 (A-B-D) and LiF-ThF4-UF4 (А-C-D), the liquidus surfaces of the wedge type. Compound R10 participates only in 2 phase reactions Q14: L+R10→A+R2(R11) and E7: L→A+R10+R2(R11). Therefore, it is assumed that in the Т-х-у-z diagram, the dots Q14 and E7 are joined without the quaternary invariant dot. On the scheme of mono and invariant states, they are joined by a line, corresponding to the reaction L→A+R10+R2(R11). Thus, a liquidus hypersurface of the compound R10 has a counter eR10R11pAR10E7Q14. References: 1. Beneš O. Thermodynamics of molten salts for nuclear applications. Dissertation. Prague. 2008. 205 p. 2. Beneš O., Beilmann M., Konings R.J.M. Thermodynamic assessment of the LiF-NaF-ThF4-UF4 system // Journal of Nuclear Materials. 2010. Vol. 405. P. 186-198. 3. Phase Diagrams of Nuclear Reactor Materials. ORNL-2548 / ed. by Тhoma R.E. 1956. 205 p. |
