Arianna Santos’ face lights up when she talks about her summer research: a nuclear engineering project that has the potential to change energy use in Canada someday.
The fourth-year materials engineering and society student has bounded into the room full of energy, with a large backpack, big glasses and a black raincoat zipped to her chin. Two weeks from midterms, she refers to her current period as a “chill” time.
Her unassuming attitude gives no hint that the work she’s doing is the first of its kind in nuclear research in Canada.
Santos, who is doing an interdisciplinary minor in nuclear, studied surrogate TRISO particles, a type of fuel used in some Small Modular Reactors (SMRs). Last summer, with support from her supervisor, Markus Piro, an associate professor of Engineering Physics, and Derek Cappon, McMaster’s Director of Reactor Operations & Maintenance, Santos tested the irradiation and characterization of capsules that mimic the behaviour of TRISO fuel in a reactor. The work was in partnership with the Canadian Nuclear Laboratories (CNL), where Santos spent two weeks this summer through the CNL Nuclear Undergraduate Research Experience program.
Arianna Santos using the hot cell manipulator arms.
What’s so special about this fuel?
TRIstructural ISOtropic (TRISO) fuel is special because each particle — which is about the size of a poppy seed — is surrounded by three different layers. That makes it effectively its own functional containment unit; it can withstand high temperatures in SMRs without melting or releasing radioactive fission products. The particles are very robust compared to current nuclear fuels and can be fabricated into pellets or spheres to be used as reactor fuel.
The fuel technology that Santos is looking at is intended to be used in advanced nuclear reactors, particularly ones that could be deployed to remote northern communities in Canada. But since it’s a much more complicated fuel type than has been previously used, engineers need to better understand how it works — and how it behaves in a reactor.
“With the recent need for clean energy and meeting the energy demand, Canada has been really supporting its nuclear side,” Santos said. “My project is to help support that and gain a research base to know that we can make and study and irradiate TRISO fuel.”
While research on how TRISO particles behave in a reactor has been done in other countries, predominantly Germany and America, it’s never been done in Canada — until now.
Unique facilities
Santos’ sample entering the scanning electron microscope.
Santos’ research used a suite of facilities at McMaster, including the McMaster Nuclear Reactor and the Centre for Advanced Nuclear Systems (CANS), where she got to work with radioactive materials remotely using the hot cells.
This type of work is usually only done at big national labs, Piro said. “Some universities will have a reactor, but then they can’t analyze it. That’s where the CANS facility is truly unique,” he said. McMaster, as far as he knows, is the only university in the world to be doing this work in-house.
Rong Guo, a manager in Nuclear Operations and Facilities and part-time PhD student, irradiated TRISO particles in the McMaster Nuclear Reactor. Santos then developed the plan to cut, mount, and polish each sample, and then put it in the CANS hot cell facilities. They used the scanning electron microscopy machine and an optical microscope to take images of the samples.
That final moment — getting optical images of the samples — was the culmination of months of research. Santos only had four samples to work with, and two of those were promised to CNL. “It was so nerve-wracking,” Santos said. “There’s the pressure of getting it right the first try.”
But Piro reminded her that the overall research goal was focused on capability testing – so even if she failed, they would still learn something. “I was expecting things to crash and burn and the whole thing to crumble, but it didn’t,” Santos said. “At the end, he was like, ‘I’m very impressed.’ And I was like, ‘Actually, me too.’”
An image from Santos’ research shows a surrogate TRISO particle cross-section taken from the optical microscope inside the hot cells. Notably, the image clearly shows all the different layers of the surrogate TRISO particle.
Agent of change
Santos, whose work has created foundational knowledge on this topic, hopes she and others will continue to build upon her research to understand if we can use TRISO fuel in Canada for small modular reactors and microreactors.
“If we can get it to work, produce it at a reasonable scale, then that just makes SMRs and microreactors more of a reality,” Santos said.
“Not only is that a scientific innovation – that’s really good for communities that are out of reach of coal, diesel, oil, further reducing Canada’s carbon emissions and giving access to clean energy and helping energy scarcity.”
Knowing that she’s setting up other people — and Canada and the world — for further successes is really exciting, Santos said – and it’s exactly what attracted her to McMaster in the first place.
“It’s been my dream to be an agent of change and scientific research,” she said. She got into engineering because she sees nuclear energy as key to achieving sustainable development and sustainability in the long term.
“I want to be part of that,” Santos said. “I want to give back to my community through that.”
A great team
Community is important to Santos, who rattles off a long list of names of the people who are part of her success.
“Dr. Piro’s research group, the people at Nuclear Operations and Facilities, my co-supervisor, Derek Cappon, the people who facilitated the radiation, the CANS people – Tony, Jaime, and Zhilin – without them, this project would not have been finished on time or to the degree that it succeeded,” Santos said.
Left-right: Rong Guo, Tony Marrone, Arianna Santos, Jaime Sanchez Ore, and Zhilin Peng. (Photo by Georgia Kirkos)
She also got great pointers from the people from CNL who had worked on compacting the TRISO particles before she got them.
“I feel like everyone has been so helpful that, although my name is on the research, it really is a team effort,” Santos said. “Without them, this would not have happened.”
And she couldn’t have asked for a better professor to work with than Piro, Santos said. “He is very supportive of students that show that they are interested. He wants you to succeed and he sets you up with opportunities all the time.”
She recalls how, when McMaster was hosting conferences and touring people through the hot cells, Piro would call on her to deliver an impromptu presentation of her research.
She’s now working on a paper for the Canadian Nuclear Society Fuel Conference, which she’ll present to people who work in the industry. And the work has already been shared, by Piro and Cappon, with other industry partners, nuclear vendors and stakeholders as a case study of capability development in Canada, specifically at McMaster.
“It’s a great case study of how we really had four things coming together,” said Piro.
“We had a really good student. We had a really good partner, CNL. We had really good facilities on campus – the reactor and the CANS facility. And we had really good support staff to support the student throughout the project.”
Santos never imagined that this would be her undergraduate experience. Even partway through her degree, there were trials: Classes were hard. Thermodynamics “nearly killed” her.
In her first research project, she battled constantly feeling like she didn’t know what she was doing. She nearly dropped out of the technical elective class – which is where she first connected with Piro – because a glitch in Mosaic made her think that she wasn’t going to get credit for it towards her degree.
Arianna Santos and Zhilin Peng, at the moment when they had their first successful surrogate TRISO particle cross section.
She stuck with it anyway.
Now, she reminds herself: You’re not supposed to know everything. You’re an undergrad and you can make mistakes. “That’s what the whole thing is for, is to learn. And you just need experiences to build you up.”
Working with her research group this summer made the whole experience worth it, she said. “Being surrounded with a community that is willing to guide you and pass on that knowledge makes you feel great (and like you’re not a burden),” she said. “Getting to work with people who are just as excited as you made my work extremely rewarding.”
And it’s surreal, for her, to be doing this work while still in university.
“I truthfully did not think I would be able to do a nuclear co-op or a job too soon,” she said. “I was like, ‘Okay, when I’m 50, I’ll be working somehow related to nuclear.’”
“And then in my third-year summer, I’m in the reactor. I get to see people put my samples in capsules and take them out of the reactor. I get to work on irradiated things… it’s just very exciting.”