Stabilities and Electron Irradiation Effects on Glass Waste Forms for Immobilization of Cs+ and Sr2+ from Pyro-processing

Abstract

Cs+ captured fly ash filter waste from pyro-processing was vitrified by glass waste form (hereinafter referred to as Cs+-glass). Carbonate Sr2+ waste including Ba2+ from pyro-processing was immobilized by glass waste form (hereinafter referred to as Sr2+-glass). 1.4MeV electrons were irradiated on the glass specimens in order to simulate the beta radiation of 137Cs and 90Sr on glass waste forms. Density, glass transition temperature (Tg), Vickers hardness and linear thermal expansion coefficient of pristine and irradiated glasses were measured. All of measured pristine and irradiated glass properties were similar to that of commercial nuclear waste glass waste forms. Chemical durability of pristine glass waste forms was estimated by product consistency test (PCT) and normalized release mass values were well below the U.S. criteria. Furthermore, electron paramagnetic resonance (EPR) and Magic angle spinning nuclear magnetic resonance (MAS NMR) were used to elucidate the existence of irradiation induced paramagnetic defect centers and structural modification of glass networks. In case of Cs+-glass, none of network formers were influenced by electron irradiation. For Sr2+-glass, only Si structure was polymerized due to electron irradiation except for B and Al structure. Work on thermal stability of a full-size canister for both glass waste forms was supported by computer simulation. As a result, the maximum temperature of glass waste forms will not go higher than glass transition temperature during an accident and preserve the glass performance.