|
Getting your Trinity Audio player ready...
|
While many research projects look decades into the future, a Western University chemistry student contributed to field research with a million-year outlook.
PhD student Jessie McDonald is part of a team investigating corrosion resistance to ensure safe nuclear waste storage within stable bedrock at Canada’s proposed deep geological repository (DGR) in northwestern Ontario. In May, McDonald travelled to the site near the Township of Ignace and the Wabigoon Lake Ojibway Nation, with staff from the Nuclear Waste Management Organization (NWMO), a microbiologist from the University of Waterloo and technicians from Alberta and Switzerland. There, the team retrieved two modules – steel canisters packed with bentonite clay containing embedded copper specimens – from a borehole 300 metres underground.
“The equipment from Alberta to go deep into the bedrock is pretty impressive,” McDonald said. “A huge truck supported a line affixed with a grappling tool to bring the modules to the surface. It also lowered, activated and retrieved a water sampling device. It was super cool.”
The proposed deep geological repository site in northwestern Ontario, where Western scientists and partners are conducting field research into the natural and engineered barriers intended to isolate and safely store nuclear waste permanently. (Submitted)
A Western research team helped deploy the modules underground in 2021, where they remained exposed to local microbes and groundwater. McDonald focused on gathering groundwater samples for the Waterloo team’s microbial analysis. Managing the microbes is key to ensuring the outer copper shell of the proposed storage containers doesn’t fail due to corrosion.
How corrosion is prevented in nuclear waste storage containers
“We want these containers to last a million years,” said James Noël, Western chemistry professor and McDonald’s PhD supervisor. “Copper is stable in groundwater. It’s the sulfide-producing bacteria, which thrive in low-oxygen environments like deep bedrock, that are the real threat to the containers’ long-term integrity.”
Where oxygen is scarce, these microbes metabolize sulfate instead, converting it into sulfide that causes copper corrosion. Bentonite clay packed around each container addresses this problem by suppressing microbial activity. The clay itself offers the bacteria nothing to feed on, and when the compacted clay is exposed to groundwater, it swells and traps microorganisms, immobilizing them so they can no longer feed and reproduce – or corrode copper.
Five years in, the copper samples from the modules are revealing evidence the suppression is working largely as predicted. McDonald is analyzing them in the lab at Surface Science Western, Canada’s foremost surface analytical laboratory serving both industry and academia.
“I do a lot of surface analysis with a scanning electron microscope, which is fun and the main basis of my project, but actually seeing the retrieval process in person, being a part of it hands-on, was awesome,” McDonald said.
After the modules were retrieved, two new modules she’d prepared were deployed into the bedrock, for analysis by future students. The work at this site isn’t McDonald’s only long-term research. She also has six modules sitting two and a half kilometres deep on the floor of the Pacific Ocean near Vancouver Island, simulating how copper and bentonite behave in a saline, high-pressure marine environment as a comparison to the Ignace site’s groundwater conditions.
Researchers confident in materials for nuclear waste storage
The research is narrowing in on exactly how tightly the bentonite clay needs to be packed. In a real repository, bentonite would be compacted into dense blocks around each container, but the rest of the shaft full of irregular rock surfaces is harder to fill to the same uniform density. Noël’s team is testing how much that density can vary before microbial suppression starts to fail.
“Our work is confirming we can go to lower compaction densities and still inhibit the microorganisms and slow the corrosion process,” Noël said.
The broader question of whether copper and bentonite are the right materials to protect used nuclear fuel and prevent its release into the environment is already settled in Noël’s mind.
“We’re confident this is the way. We know it passes the bar. Now we’re filling in the details to know by how much it exceeds the bar so we can increase our confidence in the projected lifetime of the containers,” he said.
Students learning on the nuclear waste storage project are acquiring expertise for careers in critical sectors beyond nuclear, because corrosion prevention is essential in numerous industries. Across the globe, corrosion destroys infrastructure, threatens public safety, wastes natural resources and drives carbon emissions through frequent material replacement. The cost of corrosion to Canadians alone was counted at $63 billion annually in a study from the Association for Materials Protection and Performance. Noël says the scale is hard to overstate.
“Almost everything corrodes. It costs trillions of dollars in damage every year worldwide. Corrosion is a huge problem demanding critical solutions, leaving many opportunities for students with the training they get at Western.” – James Noël, Western chemistry professor
Transparency, community engagement in nuclear waste storage research
Western is the longest-running university partner of the NWMO, a not-for-profit organization responsible for implementing Canada’s plan for the long-term management of used nuclear fuel. Research at the proposed DGR site is producing data needed to support the NWMO’s eventual repository licence application. Unlike industry-funded research where results may be kept proprietary, Noël says the NWMO wants everything to be published.
“They know the review process will include opponents – very good, scientifically literate opponents – who will evaluate what they’ve done and they want that work to be high-quality and published so everyone can see the validity of the approach for themselves,” Noël said.
Western PhD student Jessie McDonald (lower right) was part of a team that extracted materials for analysis from the site in northwestern Ontario proposed to safely and permanently store nuclear waste. (Submitted)
Before the fieldwork began, McDonald and the team completed NWMO safety training and cultural awareness training with the Wabigoon Lake Ojibway Nation, whose traditional territory includes the proposed DGR site. In 2024, residents of the Indigenous community and the Township of Ignace voted by referendum to proceed with the project, following the NWMO’s lengthy site-selection process. McDonald says relationship building is central to the research, not an afterthought.
“Being there in person to explain the science starts conversations, so everyone understands what we’re doing. Visiting the Indigenous community was personally very meaningful,” she said.
The field trip caps a research path for McDonald that began when she took a summer job in Noël’s lab before her final undergraduate year in Western’s Faculty of Science. As a PhD student, she inherited the corrosion project from the graduate student she’d worked under, Claire Tully, who is now a chemist at Candu Energy.
McDonald became a mentor herself and currently supervises an undergraduate summer student, Jacob Joseph, who works with her analyzing the samples from the modules.
“We’re really lucky in this lab to actively participate in field research. We worked closely with the NWMO to plan everything and brainstorm the best ways to proceed,” she said.
“The entire experience was definitely the most rewarding part of my degree so far.”
Learn more about how Western is preparing future leaders and global citizens.
