Nitrogen and argon solubility in liquid uranium, tungsten, and molybdenum hexafluorides

Experimental data on the solubility of argon and nitrogen in liquid uranium, tungsten, and molybdenum hexafluorides in the temperature interval 20‐90°C and gas partial pressure 180‐929 kPa are presented. The application of the most common methods of calculating the solubility of gases for the systems studied is discussed. It has been shown for fluorine [1] that the solubility in uranium hexafluoride of gases appearing together with this product during commercial production and applications can have an appreciable effect on the structure of the technological scheme used for liquefying uranium hexafluoride and on the processes in which liquid uranium hexafluoride is present. Aside from fluorine, another gas accompanying uranium hexafluoride is nitrogen which enters the technological chain when dry nitrogen is blown through the apparatus or air penetrates when the equipment is not adequately sealed. The solubility of the inert gases which are products of the fission of uranium nuclei in liquid uranium hexafluoride can be of importance in fluoride-gas methods of reprocessing irradiated nuclear fuel. For these reasons, the solubility of nitrogen and one inert gas ‐ argon ‐ in liquid metal hexafluorides was studied experimentally. The experimental procedure and the method used to analyze the experimental data are described in [1]. The experiments showed that just as in the case of fluorine the solubility of nitrogen and argon in liquid metal hexafluorides is quite high, and as usual it increases with decreasing temperature of the solvent and increasing partial pressure of the gas (Table 1). However, only in the case of uranium hexafluoride does the behavior of the gases satisfy a well-known rule: gas with a higher critical temperature and boiling point dissolves better in this solvent (Table 2). The critical temperature and the boiling point of the gases studied are taken from [2]. Using the experimental data, we shall examine the application of the most commonly used method for calculating the solubility of gases in liquids for the systems studied. Henry’s Law. As Fig. 1 shows, a linear dependence of the solubility of nitrogen in liquid uranium hexafluoride on its partial pressure is observed with adequate accuracy; this attests to the validity of Henry’s Law for this system. Henry’s constants K for the gas ‐ liquid metal hexafluoride systems studied, calculated using the well-known equation