Researchers from Washington State University have unveiled a groundbreaking technique for identifying salts in nuclear waste melting facilities. This advancement promises to enhance cleanup technologies, particularly at the Hanford site, one of the world's largest and most complex nuclear waste processing facilities.
Published in the journal Measurement, the study details how scientists employed two detectors to identify thin layers of sulfate, chloride, and fluoride salts during the vitrification process, which transforms nuclear waste into glass.
John Bassi, a student and lead author of the study, stated, "We demonstrated a technique that allows us to see the moment salts form. This enables monitoring of melting facilities and adjusting the composition of input materials." Vitrification involves loading nuclear waste into large melting units and heating it to high temperatures, after which the resulting glass is poured into cylinders for long-term safe storage.
The Hanford site presents unique challenges, having been used for plutonium production for the first nuclear bomb, resulting in waste containing nearly all elements of the periodic table. Salt formation during processing can lead to corrosion of expensive equipment and potential contamination if in contact with water during storage.
Utilizing a system developed at the Pacific Northwest National Laboratory and the Massachusetts Institute of Technology, researchers applied optical and electrical components to analyze radiation between the infrared and microwave ranges. Ian Wells, a co-author of the study and a graduate student at WSU's School of Mechanical and Materials Engineering, explained, "The uniqueness of this method lies in the fact that no additional lighting or systems are required; we can analyze the brightness of single-pixel images based solely on the heat emitted from the melt."
The system can differentiate types of salts and operate remotely, eliminating the need for sensor immersion in radioactive molten glass. Bassi noted, "This development significantly brings monitoring technology closer to practical application at the vitrification plant." Researchers anticipate that this technology could be applied in molten salt reactors and various manufacturing processes, including glass production, epoxy resins, and carbon fiber. Future plans include advancing from laboratory tests to large-scale melting trials.