High-Temperature Viscosity Measurement of LiCl-KCI Molten Salts Comprising Actinides and Lanthanides

摘要

Pyrochemical process dealing with high-temperature LiCl-KC1 molten salts comprising trivalent ions of actinides and lanthanides have been extensively investigated since it has some advantages over the conventional wet chemical processes with respect to the volume reduction of the nuclear wastes, the recycling of spent fuels, the nuclear non-proliferation resistance, etc) Physical properties of molten salt such as viscosity, density, solubility, surface tension, solubility, diffusivity, electrical/thermal conductivity, etc., are important for the design and the early fault detection of each unit processes in the pyroprocess.2 Among them, the viscosities of the high-temperature molten salts should be considered much more carefully when designing the plant as well as handling and transferring the molten fluid containing radioactive actinides and lanthanides from one unit process to the other in the pyroprocess. The viscosity is also related to the electrical properties and the structure of the liquids. However, there are only viscosity data of pure molten LiCl-KCI eutectic in a limited range of temperatures (890-1080 K). Therefore, interpolation and extrapolation are required to determine the viscosity at a specific process condition, for example, at ca. 773 K for the transfer of molten salt in the pyroprocess. In addition, there have been no previous reports on the viscosity of LiCl-KCI eutectic containing a wide concentration range of actinides and lanthanides such as uranium (U), neodymium (Nd), cerium (Ce), and lanthanum (La), which are of major interests regarding the recycling of LiCl-KCI molten salts.