Journal of Nuclear Fuel Cycle and Waste Technology

Metal chloride waste is generated as a main waste streams in a series of electrolytic processes of a pyrochemical process. Different from carbonate or nitrate salt, metal chloride is not decomposed into oxide and chlorine but it is just vaporized. Also, it has low compatibility with conventional silicate glasses. Our research group adapted the dechlorination approach for the immobilization of waste salt. In this study, the composition of SAP (SiO2-Al2O3-P2O5) was adjusted to enhance the reactivity and to simplify the solidification process as a subsequent research. The addition of Fe2O3 into the basic SAP decreased the SAP/Salt ratio in weight from 3 for SAP 1071 to 2.25 for MSAP(Fe=0.1). The experimental results indicated that the addition of Fe2O3 increased the reactivity of M-SAP with LiCl-KCl but the reactivity gradually decreased above Fe=0.1. Also, introducing B2O3 into M-SAP requires no glass binder for the consolidation of reaction products. U-SAP (SiO2-Al2O3-Fe2O3-P2O5-B2O3) could effectively dechlorinate the LiCl-KCl waste and its reaction product could be consolidated as a monolithic form without a glass binder. The leaching test result indicated that U-SAP 1071 was more durable than other SAPs wasteform. By using U-SAP, 1 g of waste salt could generated 3 4 g of wasteform for final disposal. The final volume would be about 3~4 times lower than the glass-bonded sodalite. From these results, it could be concluded that the dechlorination approach using U-SAP would be one of prospective methods to manage the volatile waste salt.

Keywords

Immobilization,Volatile radionulide,Sol-gel method,SiO2-Al2O3-P2O5,Metal chloride,pyroprocess