Chemical behavior of P,S,Cl,F, and Cr in borosilicate nuclear waste glasses

Vitrification is one technology being considered for the immobilization of the tank low-level nuclear waste (LLW) at Hanford site of Washington. The LLW contains approximately 80 wt% Na{sub 2}O and borosilicate glasses are being evaluated as the final waste form. Some of these tank wastes also have significant concentrations of one or more of the minor components such as chloride, fluoride, phosphate, sulfate, and chromium oxide. These minor components could cause potential problems in the vitrification of LLW, which include component volatility and the formation of segregated phases on the melt surface and in the final product. Volatility of halides (Cl{sup -}, F{sup -}) and sulfate (SO{sub 4}{sup 2-}) can accelerate corrosion of melter off-gas equipment and electrodes. Additionally, phase segregation on the melt surface can adversely affect the waste melting rate and can have adverse effects on glass durability. This paper describes a study on borosilicate glass with minor components added to the waste glass. Results of the retention behaviors of the components are discussed.