De-chlorination and stabilization of waste LiCl salt wastes

The spent LiCl salt waste generated from the Advanced Spent Fuel Conditioning Process (ACP) in KAERI is highly soluble in water and contains a relatively high amount of volatile element such as Cs. Therefore, this waste is very difficult to stabilize by the conventional cementation or vitrification process because of the low chemical durability of the cement waste forms and easy vaporization of the volatile radionuclides during melting. We suggested a new twostep process for a safe treatment of LiCl salt wastes containing volatile radionuclides. First, the chemical form of the soluble LiCl waste was converted into the chloride.free and less soluble hydroxide compound in an electrochemical reactor equipped with an ion exchange membrane, where an electrolytic dechlorination was performed without adding any chemical salt (electrolyte). Then a new stabilization concept, named the GRSS (Gel-Route Stabilization/Solidification) system aiming to greatly reduce the vaporization of radionuclides, was introduced to stabilize/solidify the hydroxide salt wastes. The product gels obtained from this gel-route reaction system can be fabricated to the more durable NZP(Na-Zr-P)-structure waste form through a high temperature process without or little vaporization of the radionuclides. In this paper, we described the conversion of metal chloride into metal hydroxide based on the electrochemical reaction route and the GRSS system using water-soluble raw materials and H2O as a solvent, its materials system and experimental procedure. Also, the experimental results on their applications to treat spent LiCl salt wastes are presented