a b s t r a c tActivity of uranium was determine d in gallium, indium and gallium-indium eutectic (21.8 wt.% In) based alloys between 573 and 1073 K employing the electromotive force method. In two-phase U-Ga-In alloys, uranium forms the intermetallic compound UGa 3 . Activity coefficients and solubility of uranium in Ga-In eutectic were also determine d in the same temperature range. Partial thermodynamic functions of c-U in saturate d alloys wit h gallium, indium and Ga-In eutectic were calculated.

Reaction of oxygen with solutions of neodymium chloride in LiCl and 3LiCl–2KCl melts was studied at 450 °C–750 °C. The reaction resulted in the formation of neodymium oxychloride and the effect of temperature, amount of oxygen passed through the melt (oxygen-to-neodymium molar ratio), gas phase composition (O2, O2–H2O, Ar–O2, Ar–O2–H2O) on the course of the reaction were considered. Size of particles comprising solid precipitates formed in the melt was determined. High temperature electronic absorption spectroscopy was used to determine kinetic parameters of the reaction (reaction rates, rate constants, temperature coefficients). The activation energy of the reaction was evaluated.

Reaction of lithium oxide with neodymium chloride was studied in LiCl, LiCl–KCl and NaCl–KCl based melts at various O2– : Nd3+ mole ratios. The effect of the experimental conditions on the degree and rate of neodymium precipitation, phase composition of the solid reaction products was investigated. Size of the particles in the precipitates formed at various conditions was determined to assess the feasibility of subsequent separation of the solids from the technological melts.