Before a turbofan blade can be safely installed in a jet engine, engineers need to make sure any casting materials have been cleared out from the network of narrow channels that circulate cool air inside the blade to keep the turbine from overheating. The task requires them to be able to see through metal, just as doctors use X-rays to penetrate see beneath their patients’ skin.
To do that, they use a neutron beam. Nuclear reactors produce neutrons (subatomic particles lacking an electric charge) in large quantities. Engineers beam those particles at the blades. If there’s casting material inside, such as butyl rubber, the particles will bounce off of it, alerting the engineers to its presence — and preventing potentially catastrophic engine failure.
Neutron-beam testing is just one of the many services the McMaster Nuclear Reactor offers — every commercial jet engine built in North America goes through the process. And when Chalk River’s National Research Universal reactor fully shuts down in 2018, the Hamilton facility will be the only major research reactor in Canada.
The move has left officials at Canadian Nuclear Laboratories, which oversees the Chalk River reactor, looking abroad to source neutrons. The shutdown will also leave Canada without a major source of medical isotopes, which are used to diagnose and treat some cancers.
Chris Heysel, director of the McMaster facility, argued before the House of Commons Standing Committee on Natural Resources — which is studying the future of Canada’s oil and gas, mining, and nuclear sectors — for help to increase the capacity of the Hamilton reactor and, perhaps, make up for the impending shortfall.
“If we really, truly want to support research in Canada, I think we need to enable the university [reactor] to have a research mandate,” says Heysel. “We do the best we can with the resources we have but at the end of the day we have to have a commercial focus to enable research.”
For now, the facility is self-funded; to generate revenue, the McMaster teams sells isotopes and rents out the reactor to other organizations. It currently operates below its full capacity — 5MW for 16 hours a day — but to expand its output or working hours would require more staffing and equipment.
“That type of change in operating cycle drives cost to the organization, whether it be fuel to run the car longer or people to drive it overnight and on weekends, or just the increased maintenance costs,” Heysel says.
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While international suppliers may provide enough medical isotopes to offset the Chalk River closure, Canadian researchers will have to cope with losing a major facility. Heysel says, if McMaster is to be expanded, his team would have to start planning and hiring new staff almost immediately.
Canadian Nuclear Laboratories is looking to reassign its Chalk River staff to other priorities, like research into small modular reactors (mini-reactors that could be deployed in remote northern communities) and continued work extending the life of nuclear plants across the country. For projects requiring a great number of neutrons — testing how well small-reactor components can withstand bombardment by neutrons, for example — the lab will look to an as-yet-undisclosed partner abroad.
Meanwhile, pressure is mounting on the medical research community find a new source of isotopes. They may already have found the solution in particle accelerators, which are capable of producing some of the same isotopes as reactors but don’t require radioactive fuel, instead relying on electricity and magnets. They’re also much less cumbersome to set up and to regulate.
Still, nuclear reactors are capable of putting out a much higher volume of neutrons than accelerators; researchers agree that both are essential tools for Canadian nuclear research.
“Canada has been a leader in reactor research for years, and I'd hate to see that go away,” says Paul Schaffer, associate lab director of the life sciences division at TRIUMF, a subatomic physics laboratory in British Columbia that’s home to the world’s biggest cyclotron. “With reactors having been a major supply of isotopes for years, Canada has now become reliant on foreign supply for those isotopes, so we're turning to our accelerator infrastructure to fill some of that gap so we're not reliant on foreign isotopes.”
The TRIUMF team led a successful effort to discover a means of producing the medical isotope technetium-99m using common medical particle accelerators. It’s a significant feat: technetium-99m is the world’s most commonly used medical isotope, essential to bone scans and cardiovascular tests, and previously only available from nuclear reactors.
Although particle accelerators can replicate some reactor capabilities, they can’t test small nuclear reactors via neutron beams — that task requires large-scale nuclear sources. That, says Matthew Dalzell of the Sylvia Fedoruk Canadian Centre for Nuclear Innovation, is where the Chalk River shutdown will have its farthest-reaching effects on the country’s research capacity.
“When you turn off a capability, it can be really hard to get it back,” he says. “Even if you decide 20 years from now we're going to build a new neutron reactor, who's going to run it?”
Photo courtesy of Canadian Nuclear Laboratories and licensed for commercial use under a Creative Commons licence. (See the uncropped version.)
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