Cold sintering of ceramic materials for radioactive waste management

Prof. Ho Jin Ryu from the Department of Nuclear and Quantum Engineering (NQe) has developed an innovative cold sintering technology that can be used for the safe management of radioactive waste. Environment-friendly consolidation of the ceramic matrix containing volatile radioactive elements was achieved by applying the cold sintering technology.

Article | Spring 2020

Professor Ho Jin Ryu, a professor of nuclear and quantum engineering at KAIST, has developed a new material processing technology that can stably store and dispose of ultra-long-life radioactive iodine using innovative low-temperature sintering technology of ceramic materials. The development of the technology is expected to improve the long-term disposal safety of radioactive waste by safely immobilizing volatile radioisotopes.

In order to safely capture and dispose of the long-lived radionuclides generated in isotope production facilities or spent fuel processing facilities, it is recommended to use a durable matrix having excellent bonding strength and chemical stability. Currently, a medium such as glass is used to dispose of high-level waste, but iodine with a low boiling temperature may be released into the atmosphere by volatilization in a high-temperature melting process. In particular, iodine-129 has a half-life of more than 15 million years and requires careful attention to handling and management. Therefore, an innovative low temperature process for producing solid radioactive waste forms capable of immobilization of such an ultra-long-lived radioisotope is required.

Researchers in the US and Europe, which are leading the development of new radioactive waste form materials for immobilization, are working to develop advanced ceramic matrix materials that are manufactured by using a sintering process at high temperature. However, Professor Ryu’s team has developed a low temperature sintering process to produce iodine-containing sodalite ceramic media at temperatures below 300 degrees Celsius, as shown in Figure 1. Unlike the solvent-based low-temperature sintering process, which was recently reported in the United States, the research team has developed a unique eco-friendly low-temperature sintering process without using solvent and succeeded in patent application and registration of the related technologies (Figure 2).

 

Prof. Ho Jin Ryu explained, “As a result of this research, attempts to apply low-temperature sintering technology to various high-tech fields, including bio-implants, fuel cell electrolytes and all-solid-state batteries will be actively expanded.”
Dr. Muhmood Hassan, who graduated from KAIST in Nuclear and Quantum Engineering and is a postdoctoral fellow, participated as the first author of the recently published article entitled “Non-volatile immobilization of iodine by the cold-sintering of iodosodalite” in the Journal of Hazardous Materials (doi.org/10.1016/j.jhazmat.2019.121646). Another research entitled “Cold sintering and durability of iodate-substituted calcium hydroxyapatite (IO-HAp) for the immobilization of radioiodine” was published in the February 2019 issue of Journal of Nuclear Materials (doi.org/10.1016/j.jnucmat.2018.11.024). Also, a domestic patent for this invention was registered (10-1997974) in July, 2018.