The Idaho HLW technology program, Progress in HLW disposal strategy and glass-ceramic waste form development

Irradiated nuclear fuel has been reprocessed at the Idaho Chemical Processing Plant (ICPP) since 1951 to recover uranium-235 and krypton-85 and the resulting mixed hazardous and high-level waste (HLW) has been solidified to a calcine since 1963. The Idaho HLW Technology program is evaluating options for a strategy for final disposal for ICPP HLW and is performing research to develop a reference product and process for the immobilization of ICPP HLW for repository disposal. The volume of ICPP HLW projected for future annual generation is expected to increase by four-fold compared to historical processing rates. Using existing technology, a glass waste form containing 33 wt % calcine would fill approximately 1700 canisters/yr (0.63 m3/canister) based on projected average annual waste generation rates. Thus, research is focusing on technologies that can reduce the volume of immobilized HLW, including a glass-ceramic waste form and other processes to minimize waste volume prior to immobilization. This paper describes the regulatory factors which impact future mixed hazardous/HLW management at ICPP and identifies a potential reference strategy which could be used for environmental evaluations. The characteristics of one of the candidate waste forms for immobilizing ICPP calcine, a glass-ceramic, is described, including waste loading, crystalline phase identity and leach rates