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Technology Appealing to the Core

[equipment at the RMTL]
MASc candidate Adam Brooks using equipment at the RMTL.

Building a nuclear reactor is not for the faint of heart. Between the competing and challenging demands of technical design, regulatory approval, and a potentially wary host community, the process can take years, even decades, to complete. In fact, perhaps the best reactor is one already up and running, which is why Queen’s researchers are looking at ways of extending the working lives of these critical, sometimes controversial installations.

The Reactor Materials Testing Laboratory (RMTL) is among a handful of facilities in the world dedicated to studying the physical materials used to make a nuclear site, including the piping carrying cooling liquids, fuel containers and the structures holding it all in place. Most of these items might be considered little different from what would be found in major commercial or industrial structures, with one major distinction: significant amounts of radiation.

Mark Daymond, who holds the NSERC-UNENE Industrial Research Chair in Nuclear Materials and a Canada Research Chair in Mechanics of Materials, likes to point out that radiation – the blanket term for all forms of electromagnetic energy – is everywhere. Background radiation is all around us: cosmic radiation from above, from the rocks under our feet and those used in our buildings. The difference in annual background radiation between living in Toronto or Winnipeg compared to Halifax is equivalent to the radiation received by smoking 2.5 packs of cigarettes a day. Or take an average cross-country flight on a commercial airliner and you will be exposed to similar radiation to what you would receive from a medical X-ray.

Nevertheless, the radiation levels found at the heart of a nuclear reactor are much more intense than any of these examples, and consequently much more difficult to study.

It is too dangerous for investigators to enter this hazardous environment and take samples or measurements to learn how well the place is holding up after what might be decades of continuous operation. Yet the possibility that this same radiation could be damaging the physical integrity of the reactor is too serious to overlook.

Daymond’s position was created to tackle this difficult challenge. Supported by the Natural Sciences and Engineering Research Council (NSERC) and the University Network of Excellence in Nuclear Engineering (UNENE), a not-for-profit corporation made up of public and private partners with an interest in nuclear engineering, his research chair enables him to explore how radiation affects some of the common materials that are used to build reactors.

He and his colleagues have spent the last few years establishing the RMTL, which is located in the north end of Kingston near Highway 401. The one-story building is largely indistinguishable from others found in this industrial park, although none will boast the array of technology found inside. The centerpiece is a linear accelerator that dominates a room, about the size of a passenger bus. At one end is a small container of hydrogen that serves as feedstock for protons, which this equipment accelerates into high energy beams. When these sub-atomic particles strike a sample of material, the result simulates the effect of radiation in a nuclear reactor. More importantly, the specific features of that radiation can be tailored to answer specific questions.

“You’re very limited in the kinds of tests you can do in a working reactor,” says Daymond, who explains that these facilities must always work within a narrow set of parameters as they generate electricity from day to day. Placing samples in a reactor is also problematic because they will become radioactive afterward and require elaborate handling to keep people safe, such as the use of cumbersome, lead-shielded “hot cells.” No such hot cells are required at the RMTL. If the accelerator beam strikes a piece of zirconium alloy, for example, which is commonly used in reactor tubes, the material is affected but exhibits only very low levels of radioactivity. Beyond the safety and convenience of this technique, the accelerator makes it possible to control radiation and the conditions of the sample being irradiated much more precisely than could be done in a reactor.

“You can pick the energy of your particles and the number of particles – you can dial your flux, essentially,” says Daymond. “You can control your environment very easily, including stress, temperature, or corrosive environment.”

The ability to manipulate these variables will allow the RMTL to pose questions about how reactors hold up to long-term operation and, more importantly, obtain answers that could be found in no other way. Since officially launching the lab in 2015, students and staff have been busy calibrating various detectors and examining irradiated samples to ensure that their findings reflect what would happen in a real-world setting.

“Comparing our early predictions and now our experimental results, we can see that we are able to predict how much radioactivity and damage that we’re producing in materials extremely well,” says Daymond. “During the design phase of the facility, we were doing these predictions theoretically. There can be orders of magnitude of variation in experimental conditions, so it is very satisfying that we’re still coming in spot-on.”

[tour of RTML]
Dr. Mark Daymond takes the Hon. Reza Moridi and MPP Sophie Kiwala on a tour of the RMTL. (Photo: Garrett Elliott)

Controlled by the standards and regulatory framework of the Canadian Nuclear Safety Commission, the RMTL has received $14M from the Canada Foundation for Innovation and the Ontario government, as well as support from Queen’s, its Faculty of Applied Science and Engineering, and High Voltage Engineering Europa, the Dutch-based accelerator manufacturer. The site also houses microscopes powerful enough to analyse samples at the nanometre scale, as well as equipment for testing the mechanical properties of irradiated material to determine if it has been weakened or compromised in some way. Such insights will help the owners and operators of reactors make crucial decisions about how long and how well these complex systems can function. At a time when this form of electricity generation has been praised for its lack of climate-altering carbon dioxide emissions, efforts to extend reactor working life are welcome.

“From both a financial and environmental sense, keeping existing reactors going as long as possible makes huge sense,” he concludes.

Tim Lougheed
(e)AFFECT Issue 11 Spring/Summer 2017