Measurement of the Kinematic Viscosity of the Eutectic LiF–AlF3

Abstract

The kinematic viscosity of a eutectic salt mixture with the molar composition 0.855LiF–0.145AlF₃ at temperatures to 850°C is measured by means of damped torsional vibrations of a cylinder with the experimental liquid. This salt mixture is of interest for separating actinides and lanthanides during reprocessing of spent nuclear fuel. Below 800°C the behavior of the system is found to differ from that of a normal liquid. Such behavior is explained by precipitation on solid surfaces. The precipitated fraction of the material is evaluated as a function of temperature. An analytical expression is obtained for the kinematic viscosity at temperatures above 800°C. The standard deviation of the kinematic viscosity evaluated assuming the dispersion to be independent of temperature equals 0.006·10^–6 m²/sec. The total error of measurement does not exceed 3%.