Canada remains anti-nuke, but its potential path to the bomb is getting shorter

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For decades, Canada’s official policy on nuclear weapons has been that they shouldn’t exist, and there is no sign that principle is about to be abandoned.

But for reasons of history and geography, Canada is also one of the world's non-nuclear countries with the easiest technical path to a nuclear weapon. And because of the particular design of its CANDU reactors, it would also be one of the countries best-positioned to produce weapons-grade fissile material without tripping international alerts — although such a move would carry huge geopolitical risks.

Technological changes that are expected in the coming years will likely make Canada even more of a threshold nuclear arms power than it is today, whether it chooses to cross that threshold or not.

"The only thing that inhibits Canada is the will to do it, the political decision to do it," said nuclear weapons expert Steve Fetter of the University of Maryland, who served as head of national security and international affairs in the White House Office of Science and Technology Policy.

He's also a member of the National Academy of Sciences Committee on International Security and Arms Control, and the originator of the "Fetter Model," the standard technique used in arms control verification for detecting the presence of nuclear warheads through radiography.

"Canada was a major participant in the Manhattan Project, as was the U.K.," Fetter told CBC News. "Immediately after the [Second World War], we froze you out and said, 'No co-operation.' So Canada decided — as did the U.K. — to develop its own completely indigenous program."

The U.K., of course, went on to become a nuclear arms power, while Canada did not.

Canada designed the CANDU heavy water reactors that use unenriched, natural uranium containing only about 0.7 per cent of the U-235 isotope needed to make nuclear weapons. Most of the world’s 440-odd nuclear reactors are light water units that require uranium enriched to about four per cent U-235 content.

For this reason, and despite being the world’s second-biggest producer of uranium, Canada has never enriched domestically.

However, the CANDU is anything but a proliferation-proof technology, because it is not only the best kind of reactor for producing the plutonium-239 isotope used in bombs, but also for concealing its production.

"You do produce plutonium in a light water reactor," said Fetter. "But that plutonium is contained in highly radioactive spent fuel and it's not really high-quality."

Light water reactors work by loading enriched uranium, sealing the reactor core and then running it for 18-24 months before shutting down, reopening the core and replacing fuel. This makes it relatively easy to keep track of how much fuel is going in, and what is happening to the spent fuel that comes out. It’s impossible to secretly swap fuel rods while the reactor is generating power.

The Canadian heavy water reactor doesn’t work that way.

The Bulletin of the Atomic Scientists members including Steve Fetter, right, reveal the Doomsday Clock, set to 85 seconds to midnight, during a news conference in Washington, D.C., on Jan. 23, when they announced that the planet is closer than it's ever been to destruction as Russia, China, the U.S. and other countries become 'increasingly aggressive, adversarial and nationalistic.' (Pablo Martinez Monsivais/The Associated Press)

"All uranium-fuelled reactors produce plutonium. The issue with the CANDU is that it has online refuelling," explained Ed Lyman, director of nuclear safety for the Union of Concerned Scientists in Washington, D.C. "You're refuelling continuously, which makes it harder for the IAEA [International Atomic Energy Agency]."

Canada, which produces all of its own uranium, would be in a strong position to divert fissionable material undetected if so inclined, say the experts.

The plutonium produced in a heavy water reactor is also much easier to turn into a nuclear weapon, said Fetter.

"Of the countries that have made nuclear weapons with plutonium, many of them have used a heavy water reactor," he said.

That’s why India used a Canadian heavy water reactor to produce its first nuclear weapon in 1974, an all-plutonium implosion-type bomb. The "Smiling Buddha" test was the first to break the nuclear monopoly of the "Big Five" UN Security Council powers.

Fetter said the U.S. had heavy water reactors only for the purpose of producing plutonium and tritium. (Tritium, also produced in abundance by the CANDU reactor, is another critical component of a modern two-stage thermonuclear weapon that Canada has in abundance.)

Canada is also branching out into a new kind of technology that will require enriched uranium: the small modular reactor (SMR). Some of the proposed SMRs would use uranium enriched to a level as high as 20 per cent, known as high-assay low-enriched uranium (HALEU).

HALEU is already a proliferation concern in itself, said Lyman.

"Anything below 20 per cent is considered low-enriched uranium and has a much lower level of oversight. The IAEA considers it indirect-use material you can't directly use in a bomb,” he explained. "But there's evidence, both historical and technical, that that's not true, and that the actual cutoff for weapon-usable uranium is below 20 per cent. Could be 15 per cent, could be 10 per cent.

"And so I worry about this push for advanced reactors, SMRs that use HALEU up near 20 per cent, like the ARC 100 in Canada, that the material itself is in the dangerous band. And if Canada were to pursue a whole fleet of SMRs using HALEU, and especially if they were to build their own enrichment plants to support that, that might give them a threshold capability for bombs, even if they never make highly enriched [over 20 per cent] uranium."

ARC Canada points out that its proposed reactor in New Brunswick, which would become the only commercial fast-breeder reactor in the world outside Russia, mitigates against proliferation risks by having a long fuel cycle with a core that stays sealed for 20 years.

But there’s another factor: The arrival of SMRs that consume enriched uranium has got the government of Canada thinking about enrichment.

Employees walk down a tunnel at Cameco's Cigar Lake uranium mine in Cigar Lake, Sask., on June 15. Despite being the world’s second-biggest producer of uranium, Canada has never enriched domestically. (Liam Richards/The Canadian Press)

To enrich or not to enrich

"Any country which has a complete fuel cycle is a latent nuclear weapons country, in the sense that it is not far from making a nuclear weapon," said former IAEA director and Nobel Peace Prize laureate Mohamed ElBaradei.

Scientists consulted by CBC News said Canada would probably have little economic motive to build its own enrichment facilities. Canada’s nuclear energy strategy foresees importation of enriched uranium from France and the U.S. in the immediate future, even though that often means buying back Canadian-mined uranium after other countries have added value.

The longer-term question of whether Canada should develop domestic enrichment capability remains under assessment. - Canada's nuclear energy strategy

But the strategy also notes that "geopolitical volatility has exposed fragility in nuclear fuel supply chains at every stage — mining, milling, refining, conversion, enrichment, and fabrication."

Canada plans to double its exports of uranium in raw form, "but there is also a compelling case for expanding downstream capabilities selectively."

Domestic enrichment might not save Canada money, but would increase its strategic autonomy.

"Canada will continue to monitor the energy security implications of these supply chains," says the strategy. "The longer-term question of whether Canada should develop domestic enrichment capability remains under assessment."

A handful of non-nuclear arms powers have developed enrichment facilities. They include Brazil, Japan, Argentina, Germany and the Netherlands, but only Brazil combines a modern centrifuge facility with a large domestic supply of uranium.

Japan could theoretically produce weapons-grade uranium, but its nuclear technology, like South Korea’s, is largely American, its nuclear program is subject to strict inspections, and it has no uranium mines of its own — in fact it buys much of its supply from Canada.

A Canadian company, Cameco, is currently exploring the next frontier of uranium enrichment. The SILEX method uses laser excitation to separate U-235 more quickly and efficiently than spinning it in a centrifuge.

Already, a centrifuge facility can fit in an area the size of a high school gym. SILEX, said Fetter, "potentially could be even smaller and use less energy than centrifuge enrichment, which would make it harder to detect a clandestine facility."

The SILEX project has already received U.S. government funding and acquired land in western Kentucky for a plant expected to be operating by 2030.

For all the Carney government’s talk of "a more dangerous and divided world," there is still no public signal that Canada might abandon its long-held opposition to nuclear arms.

If the strategic situation were to change, Canada would have to decide whether to go the open route and formally depart the Treaty on the Non-Proliferation of Nuclear Weapons (NPT), or pursue nuclear arms through a clandestine program as other countries have done with a mixed record of success.

Plasma physicist Tara Drozdenko worked on nuclear weapons issues under the administrations of Barack Obama and George W. Bush. She represented the United States on NATO's Senior Group on Proliferation, and headed the Country/Regime Sanctions Unit at the U.S. Department of Treasury, where she managed the government's nuclear-related sanctions on countries such as Iran and North Korea.

Today, she’s not sure Washington remains committed to preventing proliferation, or how it would react to a Canadian decision to leave the NPT.

"In a normal administration, there would be condemnation, there would be reproach, there would be a lot of diplomatic efforts," she told CBC News. "I don't know what would happen in this administration. Would there be threats? Would there be some people that are like, yeah, everybody should have nuclear weapons? I really can't predict what this particular administration would do."

A TV screen shows a report of North Korea's multiple rocket launchers during a news program at the Seoul Railway Station in Seoul, South Korea, on April 23, 2024. (Lee Jin-man/The Associated Press)

So far, all the countries that have developed nuclear weapons — Israel, South Africa, India, Pakistan and North Korea — began their efforts in secret.

Drozdenko says Canada’s own nuclear industry, the design of its reactors and the fact that it has the world’s best uranium deposits would all give it a strong hand were it ever to pursue such a risky course.

"Canada is probably really well-positioned to do that, if Canada was determined," said Drozdenko. "You have a lot of land that's not heavily populated, and if you used technologies that didn't have a lot of energy or thermal signature, I don't think the U.S. has its intelligence assets pointed at Canada right now."

At some point, such a program would inevitably become known.

"It would require withdrawal from the non-proliferation treaty, which would be really impactful to the treaty worldwide, especially as a NATO country and up until now a pretty close ally of the U.S. I think that would be pretty catastrophic to that treaty,” Drozdenko said.

Fetter said Canada could probably easily assemble a simple “gun-type” nuclear weapon like the one used on Hiroshima, but would face scientific hurdles if it tried to build a modern thermonuclear weapon without conducting tests. North Korea required half a dozen tests to get there.

In the U.S., Russia and China, supercomputers today have replaced actual testing. Canada has the computing capacity but lacks the detailed data that nuclear arms powers have assembled on materials science, and the complicated timing and interactions inside a nuclear warhead — some of the most closely guarded secrets in the world.

But Fetter also said he didn’t expect North Korea to be able to put a modern, two-stage thermonuclear warhead on a ballistic missile and make it work.

"Canada has a lot of smart people," he noted.

With Canada embarked on a new era of greater military spending, including the purchase of modern submarines and its first foray into the world of cruise missiles, it is clearly assembling elements that could bring it closer to "breakout" as a nuclear arms power, if it desired.

The question of how other countries would react is the unknowable factor, said Drozdenko.

"Does Canada want to be in the position of North Korea, the pariah state that's making clandestine nuclear weapons?" she asked.

So far, the answer has always been no.