Glass-ceramic composite wasteform to immobilize and stabilize a uranium-bearing waste generated from treatment of a spent uranium catalyst

Abstract A disposal method for radioactive waste should be carefully chosen on a case-by-case basis, taking into consideration, chemical and radiological properties of the waste, acceptance criteria required for disposal site, and circumstance of the country where the waste is generated. A large volume of uranium-bearing waste (UO2-Sb2O3-Fe2O3-SiO2 mixture oxide) from to be finally disposed will be generated from a process to treat spent uranium catalyst in South Korea. This worked studied a glass-ceramic composite wasteform tailor-made for the final uranium-bearing generated from the process. The physicochemical properties of the prepared glass-ceramic wasteform were evaluated to ensure that the waste acceptance criteria for a disposal site in South Korea could be met. The mechanism of forming the glass-ceramic matrix and its final structure were investigated by using TG-DSC, SEM-EDS and XRD. The optimal sintering temperature and content of B2O3 to be added were 1100 °C and approximately 2–3 wt % in the total uranium-bearing waste, respectively. The SiO2, Fe2O3 and Sb2O3 in the target uranium-bearing waste formed a glass phase with help of B2O3, and SbFeO4 oxide phase, respectively. Both UO2 and Al2O3, which exhibit high melting points, remained as refractory phases in the sintered body. Conversion of the uranium-bearing waste into a glass-ceramic composite matrix wasteform was confirmed to be an effective way to deal with the uranium-bearing waste in terms of volume reduction of the waste and waste acceptance criteria for the disposal site in Korea.