RICHLAND, Wash. - Researchers at DOE’s Pacific Northwest National Laboratory (PNNL) and Washington State University (WSU) are seeking insight into the long-term behavior of glassified nuclear waste to ensure its durability hundreds of years into the future.
The research supports EM’s plans to turn nuclear and chemical waste currently stored in underground tanks at Hanford and other EM sites into a durable glass form. Specifically, it adds to the science that helps provide assurances for the safe disposition of waste and protection of the environment.
Glass has exceptional durability but can corrode over long periods with exposure to water. The rate of corrosion is dependent on factors including particular glass formulation, chemistry of the corroding water, presence of minerals, and temperature.
Glass corrosion does not represent a simple dissolution of material. Instead, the exposed glass undergoes changes in structure and composition to form rinds of new material called “alteration layers."
Dr. Joelle Reiser used state-of-the-art characterization tools to compare the structure of alteration layers created from exposure of glass to corrosive conditions with similar materials created synthetically. Comparing the well-known formation of the synthetic material to those of the glass alteration layers gives insight into how corrosion proceeds over long periods.
“We will be disposing of nuclear waste in a glass waste form, and it will be stored for a long time. Understanding these dissolution processes is not easy, but it will allow us to model the performance of the waste glass over these long time periods and under various geologic conditions," said Dr. Nicholas Machara, a physical scientist in EM’s Technology Development Office. “That information will allow the Department to bound the long-term risks from nuclear waste, inform the selection of storage options, and perhaps expand the processing conditions and formulations for producing nuclear waste glass."
Reiser conducted her work on glass waste forms at PNNL in the laboratory of Dr. Joe Ryan as part of her doctorate research at WSU. Her work included pioneering the use of the annihilation of small particles of anti-matter to characterize the alteration layers of glass and better understand their structure. Reiser recently received her doctorate from WSU and works at PNNL to extend this work to glasses that can immobilize a wider variety of waste.
Source: U.S. Dept. of Energy, Office of Environmental Management
