Journal of Nuclear Fuel Cycle and Waste Technology

This study suggested a new method to stabilize molten salt wastes generated from the pyro-process for the spent fuel treatment. Using conventional sol-gel process, SiO2-Al2O3-P2O5 (SAP) inorganic material that is reactive to metal chlorides were prepared. In this paper, the reactivity of SAP with the metal chlorides at 650~850, the thermal stability of reaction products and their leach-resistance under the PCT-A test method were investigated. Alkali metal chlorides were converted into metal aluminosilicate(LixAlxSi1-xO2-x) and metal phosphate(Li3PO4 and Cs2AlP3O10) while alkali earth and rare earth chlorides were changed into only metal phosphates (Sr5(PO4)3Cl and CePO4). The conversion rate was about 96~99% at a salt waste/SAP weight ratio of 0.5 and a weight loss up to 1100℃ measured by thermogravimetric analysis were below 1wt%. The leach rates of Cs and Sr under the PCT-A test condition were about 10-2g/m2・day and 10-4g/m2・day. From these results, it could be concluded that SAP can be considered as an effective stabilizer for metal chlorides and the method using SAP will give a chance to reduce the volume of salt wasteform for the final disposal through further researches.

Keywords

Stabilization,Volatile radionulide,Sol-gel method,SiO2-Al2O3-P2O5,Metal chloride,Wasteform