During a liquid sodium experiment, things are going right when it doesn’t seem like anything is happening. In the Thermal Hydraulics Lab at Fort Lewis College, Engineering students and Billy Nollet, nuclear engineer and associate professor of Physics & Engineering, are running a Moving Magnet Pump for liquid sodium. Everyone is thrilled with the apparent inactivity.
Inside a “glove box,” a sealed plexiglass and stainless-steel box with thick rubber gloves constructed into the face so someone can work in the box unexposed while maintaining an inert atmosphere, the group is testing their unique pump design as well as a repertoire of other innovative instruments. Save for a few blips on a computer screen, and the dangling gloves slowly rising like Frankenstein’s Monster as the box pressurizes, there’s not much happening to the untrained eye.
“If we don’t see anything happen ever, that means we did our job,” says Andrew Napora, a senior Engineering student. “It’s really hard to do anything to a substance that you can’t see or touch, or put any kind of instrumentation inside of.”
Liquid sodium is a silvery molten metal that chemically reacts, potentially violently, with air and water and therefore needs a perfectly sealed system. Nollet and his students are using an MMP, an induction motor with magnets to pick up and move the melted sodium through a loop, to experiment with measuring and controlling the material’s impurity content and temperature. And their results are critical to the larger experiment going on in the nuclear power industry – how to develop more efficient, safer, and economical reactors.
Like the antifreeze in a car, liquid sodium can be used as a coolant in a nuclear reactor. These Sodium-cooled Fast Reactors were conceptualized in the U.S. in the 1950s, but the ones built were mothballed and decommissioned as water-cooled reactors became the preferred model. The main advantage of liquid sodium as a coolant compared to water is that it can operate at much higher temperatures (500-600 C) at ambient pressures, increasing both the efficiency and inherent safety of the system while producing less nuclear waste – but it is much more volatile. A leaky system would corrode the oxygen-hungry sodium instantly and jam up moving parts. If water were to come in contact, there could potentially be a hearty explosion. Still, with already more than 90,000 metric tons of nuclear waste just in the U.S. and a climate crisis exacerbated by fossil fuel use, a reimagining of the industry is due.
“The most romanticized version of what we’re trying to do is solve the energy crisis with the cleanest and safest energy on Earth,” says Nollet. “Energy production in general is a dangerous thing for humans to do, but we would also argue it is a necessary thing for us to do. It enables our way of life, and it enables everything that we do. And so, within those confines, I think it is our responsibility to find the safest energy we possibly can, and there’s no statistic that would argue with the fact that nuclear is the safest and cleanest energy on Earth.”
Nollet specializes in experimental thermal hydraulics and has been working in support of cooling systems for Sodium-cooled Fast Reactors for ten years. He arrived at FLC and opened the Thermal Hydraulics Lab in 2013. He’s worked on various instruments, pumps, filters, and mechanical systems associated with liquid sodium cooling systems.
"Many of the world’s energy and environmental challenges of the future are being tackled by FLC undergrads today. We relentlessly carry out this work in hopes that our innovations and newly-trained scientists will make a better tomorrow."
Billy Nollet, associate professor of Physics & Engineering
In 2018 he co-wrote and won a grant with the University of Wisconsin-Madison worth $365,000 for “Liquid Sodium Impurity Research” as part of the Versatile Test Reactor project. Congress allocated $35 million to the Department of Energy’s Office of Nuclear Energy to support advanced nuclear reactor research and development, and in turn DOE created the VTR project and distributed funding to four national labs and universities across the country. This grant was renewed in July 2019 for another $365,000.
“Fort Lewis’ VTR grant focuses on oxygen detection and instrument design for application in sodium systems, so specifically we are working on helping mitigate or analyze corrosion in these types of reactors for the future,” says Nollet.
Additionally, Nollet is part of a three-year, $800,000 grant through the Nuclear Energy University Program, of which $120,000 goes to FLC. The funding is allocated to national laboratories and then redistributed to universities to design better liquid sodium pumps – like the one in the glove box.
Rachel Day (Engineering, ’18) was the lead on pump design and preliminary testing while Dustin Mangus (Engineering, ’19) continued testing in the glove box through Summer 2019.
“We need to prove that our pump is going to be effective, that it’s not going to leak, and to test its efficiency and its ability to move liquid sodium through without having any dynamic seals or any moving parts that could cause leaks,” says Mangus.
Under Nollet’s guidance, these FLC undergrads are doing research and experiments that typically only graduate students at larger universities get to do. Mangus graduated in Spring 2019 and right after he completes his summer research with Nollet, he’ll head to Oregon State University to pursue his doctorate and continue researching liquid sodium thermal hydraulic systems. Mangus’ new faculty advisor from OSU was in the lab for the test and said there is likely no other undergrad in the country with as much hands-on experience as Mangus.
“It’s unheard of, which is why we’re scooping him up at Oregon State,” says Sam Briggs, assistant professor of Nuclear Science & Engineering at OSU. “He’s got the technical know-how to be in a [glove] box and work on these types of systems, and typically that’s something we have to train on our own.”
This summer, Briggs and other faculty and graduate students from OSU visited FLC and Nollet to learn what it would take to create their own liquid sodium lab.
“These are the types of capabilities that we’re working to develop at OSU,” says Briggs. “We’re essentially here trying to get some practical experience, and learn all the details you’re not going read about in papers regarding how you actually construct and operate these systems. We’re in the process of building something similar, but hopefully scaled up with capability do some interesting materials science work.”
Briggs’ background is in material science as it relates to radiation damage in nuclear environments. A big push in the nuclear industry right now is materials compatibility in these advanced environments and determining how to construct sodium-cooled, and even molten-salt cooled systems that will survive for forty plus years. Nollet has done a lot of work on the experimental side of liquid sodium research, which Briggs will draw on to develop the material science aspects at OSU.
“We want to leverage the capabilities of both institutions to be doing this state-of-the-art research and move the field forward,” says Briggs. “The nuclear industry has historical experience with sodium-cooled systems, but with the instruments and analytical technologies available to us today, we can do more advanced experimentation and get a much better understanding for the nuances involved in operating these systems and what factors actually dictate performance.”
Currently, the only academic institutions contributing to this scale of sodium work for the industry are MIT, University of Wisconsin-Madison, Argonne National Laboratory, and FLC. Oregon State University will now be joining that list. Nollet said his not-so-secret plan is to prepare his top students for graduate school at larger universities like Madison and OSU. The collaborative liquid sodium research has created a kind of pipeline of well-trained FLC undergrads, like Mangus, into those graduate programs (three of Nollet’s other alumni are already in doctorate programs at Wisconsin-Madison).
Nollet has also helped place around a dozen students into different Research Experiences for Undergraduates at various universities and labs and four different papers have been published with his undergraduate students as co-authors.
“Many of the world’s energy and environmental challenges of the future are being tackled by FLC undergrads today,” says Nollet. “We relentlessly carry out this work in hopes that our innovations and newly-trained scientists will make a better tomorrow.”