Electrochemical and Thermodynamic Properties of Lanthanum in a Chloride Melt – Liquid Metal System

Abstract

The behavior and properties of lanthanum in a “molten salt – liquid metal” system in relation to pyrochemical reprocessing of spent nuclear fuels was considered. Temperature dependencies of lanthanum formal standard electrode potential E* La/La(III) and Gibbs free energy change of lanthanum trichloride formation in LiCl–KCl–CsCl eutectic based melts were obtained between 668–976 K. Also the behavior of lanthanum was studied in Ga–Al (1.6 wt. % Al) and Ga–Zn (3.64 wt. % Zn) eutectic based metallic alloys, and activity, solubility and activity coefficients of lanthanum determined.

Solubility of Lanthanum in Liquid Alloys with Gallium and Indium

“…In the present study, three independent techniques were employed for determining lanthanum solubility in gallium-indium-based alloys, i.e., sedimentation (precipitation), filtration and centrifugation. The experimental procedures and setups used for performing the measurements were described in detail previously [18][19][20]. The sedimentation technique involved taking samples of liquid alloys saturated with lanthanum at a given temperature and determining the lanthanum concentration by chemical analysis.…”

“…Temperature dependencies of activity coefficients can be calculated from the difference in the corresponding dependencies of activity and solubility [19,33]. The activity of β-lanthanum in alloys with gallium [20] and indium [26] can be expressed by the following equations: loga La(Ga) = −16,193 T −1 + 6.941, (573-1081 K)…”

Anodic dissolution of gallium in alkali metal chloride melts

“…Developing a feasible reprocessing technology requires comprehensive and reliable information about the electrochemical properties of all elements involved in the process. In recent years behavior of f-elements in gallium-containing alloys in relation to SNF reprocessing attracted considerable attention [15][16][17][18]. Electrochemical and thermodynamic properties of uranium [19][20][21][22][23][24] and various rare earth metals representing fission products [19][20][21][22][23][25][26][27][28][29][30][31][32] were extensively investigated in various gallium-containing alloys.…”