Solidification of Molten Salt Waste by Gel-Route Pre-treatment

This study suggested a new method for the solidification of molten salt waste generated from the electro-metallurgical process in the spent fuel treatment. Using binary material system, sodium silicate and phosphoric acid, metal chlorides were converted into metal phosphate in the micro-reaction module formed by SiO2 particles. The volatile element in the reaction module would little vaporized below 1100 .deg. C. After the gel product was mixed with borosilicate glass powder and thermally treated at 1000 .deg. C, Li exists as Li3PO4 separated from glass phase and, Cs and Sr would be incorporated into an amorphous phase from XRD analysis. In case of the addition of ZrCl4 to the binary system, the gel products were transformed into NZP structure considered as an prospective ceramic waste form after heat-treatment above 700 .deg. C. From these results, the gel-route pretreatment can be considered as an effective approach to the solidification of molten salt waste by the confirmed process or waste form and this also would be an alternative method on the ANL method using zeolites in USA by the confirmation of its chemical durability as an future work.