Processes for immobilization of high-level solid wastes by glass and ceramic matrices

Processes for the immobilization of waste SiC hulls and fissile particles from reprocessing of HTGR fuels are presented. Compressed cylinders of waste-matrix material were formed under pressures of approx. 35, 71, or 142 MPa and sintered at temperatures ranging from approx. 500 to 10250C for approx. 1 h. The cylinders containing 50% SiC-25% soft glass-25% red clay possess the most desirable properties (high mechanical strength, low surface area, and low leachability) of the several different compositions studied. Within the pressure and temperature ranges studied, the pressure of cylinder formation and the sintering temperature appear to have relatively minor effects on those properties except for the initial cesium leachability. Higher pressure and temperature would tend to reduce the initial leachability significantly. 5 tables