Development of iron phosphate glass with Cs sorption function; Study on suitable chemical composition for glass filter and its sorption mechanism

Mitamura, Naoki*; Tsuzuki, Tatsuya*; Amamoto, Ippei

Iron phosphate glass could be used to immobilize the high-level radioactive waste (HLW) and has the possibility to function as a Cs sorpant. However, the glass must endure high temperature from about 350C, the melting point of LiCl-KCl electrolyte, to 600C, the operational maximum temperature. In this study, we have successfully developed the iron phosphate glasses functioning as Cs sorpant, possessing heat resistance, etc.. To prevent the glass softening at temperature around 600C, alkali metal oxides, alkaline-earth metal oxides, alumina and/or titania were added into the FeO-PO glass. Through soak experiments of the glasses in molten salt(LiCl-KCl)containing CsCl, it was found that those glasses immobilize Cs by reacting with CsCl and formed crystal phase of CsFeCl and/or CsFeCl. This Cs sorption function is peculiar to the developed iron phosphate glasses.