An evaluation of glass-crystal composites for the disposal of nuclear and hazardous waste materials

Waste forms made of a glass-crystal composite (GCC) are being evaluated at Argonne National Laboratory for their potential use in the disposal of low-level nuclear and hazardous waste materials. This waste form is being developed within the framework strategy of DOE`s minimum Additive Waste Stabilization (MAWS) Program. The MAWS protocol involves the blending of multiple waste streams to achieve an optimal feed composition, which eliminates the need to use large amounts of additives to produce an acceptable waste form. The GCCs have a particularly useful utility in their ability to incorporate waste streams with high metal contents, including those that contain large amounts of scrap metals, and in their potential for sequestering radionuclide and hazardous constituents in corrosion-resistant mineral phases. This paper reports the results from tests conducted with simulated feeds representative of potential DOE and industry waste streams. Topics addressed include the partitioning of various radioactive and hazardous constituents between the glass and crystalline portions of the waste form, the development of secondary phases on the altered sample surfaces during corrosion testing, and the fate of waste components during corrosion testing, as indicated by elements released to solution and microanalysis of the reacted solid samples