Melt-crystallization monitoring system for the purification of 10 kg-scale LiCl salt waste

Salt waste treatment process in the pyrochemical process is under development to separate or concentrate fission products from the LiCl salt waste and to minimize waste volume by recycling the purified LiCl salt into the electrochemical process. In particular, the Cs nuclide in the LiCl salt waste is difficult to separate by chemical method, so that melt-crystallization method has been employed and engineering-scale melt-crystallization system capable of 20 kg/batch treatment has been designed and installed at the PyRoprocess Inactive integrated Demonstration (PRIDE) facility. In this study, in order to evaluate scaled-up design of melt-crystallization process, the preliminary crystallization test was conducted with 10 kg LiCl salt waste having surrogate Cs, Sr, and Ba nuclides. In consideration of temperature gradients generated inside the crystallization vessel owing to the scale-up, melt-crystallization monitoring system was developed. Using the monitoring system, we could obtain purified LiCl crystal with uniform distribution of quantity on 6 crystallization plates and high separation efficiency of over 90% at various cooling conditions.