Last week I had the privilege of receiving an invitation from Dr. Jason Donev to  spend two days at the University of Calgary attending a series of lectures by Dr. Jeremy Whitlock. The lectures covered the history of nuclear science in Canada, the development of Small Modular Reactors (SMRs), nuclear non-proliferation, and “the exciting road ahead for sovereignty, security, and sustainable development in Canada.”

It was an eye-opening experience. I came away with a renewed appreciation for how deeply Canada has shaped, and continues to shape, the global nuclear landscape.

I was surprised to learn that, immediately after the Second World War, Canada possessed the world’s second-largest nuclear program and operated the most powerful research reactor on Earth. Canada was also among the very first nations to sign the Nuclear Non-Proliferation Treaty, establishing an early and consistent commitment to peaceful uses of atomic energy. 

Today, Canada is advancing one of the most carefully designed and community-supported deep geological repositories for long-term nuclear waste storage anywhere in the world.

These milestones are not isolated achievements. They are part of a coherent, seven-decade story of innovation, international collaboration, pragmatic engineering, and deliberate choices about safety, sovereignty, and sustainability.

This week, we’re tracing that story. From early 20th-century scientific breakthroughs and wartime contributions, through the development of the world-leading CANDU (Canada Deuterium Uranium) technology, to today’s focus on SMR deployment, uranium leadership, and responsible waste management. It is a distinctly Canadian nuclear narrative: technically ambitious, internationally responsible, and humbly world-class.

A Brief History of Nuclear in Canada

Canada’s nuclear story is one of pioneering innovation, wartime collaboration, and enduring leadership in peaceful atomic energy. From early 20th-century scientific breakthroughs to becoming the second nation to achieve controlled nuclear fission, Canada has carved out a distinctive path in the global nuclear landscape. The development of the homegrown CANDU reactor has enabled reliable, low-carbon electricity generation while supporting world-class research, medical isotope production, and uranium exports.

Early Beginnings (1900s–1930s)

In 1908, Ernest Rutherford, working at McGill University in Montreal, was awarded the Nobel Prize in Chemistry for his research on radioactive decay. In 1930, prospector Gilbert Labine discovered radium and uranium deposits at Port Radium in the Northwest Territories, marking the start of uranium mining in Canada. By the 1930s, George C. Laurence at the National Research Council (NRC) in Ottawa designed one of the world’s first nuclear reactors.

World War II and Post-War Research (1940s–1950s)

During World War II, Canada played a key role in Allied nuclear efforts. In 1942, a joint British-Canadian laboratory opened in Montreal under the NRC, focusing on heavy-water reactor designs. In 1944, construction began on the Chalk River Laboratories in Ontario, where an engineering team developed nuclear technology as part of broader wartime research. On September 5, 1945, the Zero Energy Experimental Pile (ZEEP) reactor at Chalk River achieved the first controlled nuclear fission reaction outside the United States, making Canada the second country to do so.

In 1946, the Atomic Energy Control Board (AECB) was established as Canada’s federal nuclear regulator. The National Research Experimental (NRX) reactor, then the world’s most powerful, began operations at Chalk River in 1947, followed by the National Research Universal (NRU) in 1957. These facilities supported radioisotope production, materials testing, and reactor design. In 1952, Atomic Energy of Canada Limited (AECL) was created as a Crown corporation to promote peaceful nuclear energy uses. The NRX experienced a core damage accident in 1952 but was rebuilt and restarted within 14 months.

In the mid-1950s, Wilfrid B. Lewis led the development of the CANDU reactor, a heavy-water moderated and cooled design using natural uranium, in collaboration with AECL, Ontario Hydro, and Canadian General Electric. Also in 1951, Canada pioneered cobalt-60 radiation therapy for cancer treatment, with the first units built and treatments delivered in Ontario and Saskatchewan.

Expansion and Commercialization (1960s–1980s)

The 1960s marked the shift to power generation. In 1962, the Nuclear Power Demonstration (NPD) reactor in Rolphton, Ontario, became Canada’s first electricity-producing reactor and CANDU prototype, with a 20 MW equivalent (MWe) capacity. AECL also developed the first commercial cobalt-60 sterilizer for food and medical supplies. In 1967, the 200 MWe Douglas Point reactor in Kincardine, Ontario, came online as the first full-scale CANDU unit.

The late 1960s saw the development of the SLOWPOKE (Safe Low-Power Kritical Experiment) (Safe Low-Power Kritical Experiment) research reactor, a low-maintenance miniature design used for experiments and still operating at some Canadian institutions. Commercial expansion accelerated in the 1970s: Pickering A (four units, 2,060 MWe) became the world’s largest nuclear station by 1973. The first CANDU export was to India in 1972. Bruce (1970s) and Darlington (1980s) stations followed, with Point Lepreau in New Brunswick and Gentilly-2 in Quebec online by the early 1980s. Uranium mining boomed, with major sites in Saskatchewan like Rabbit Lake and McArthur River.

Modern Developments (1990s–Present)

In 1994, Bertram Brockhouse won the Nobel Prize for neutron scattering research at Chalk River. The Canadian Nuclear Safety Commission (CNSC) replaced the AECB in 2000. Nuclear power grew to provide about 15-17% of Canada’s electricity by the 2000s, primarily in Ontario. The Nuclear Waste Management Organization (NWMO) was mandated in 2002 for long-term fuel storage.

Refurbishments extended reactor lives: Ontario’s $26 billion program for Darlington and Bruce began in 2015, with several units restarted by 2023-2024. Point Lepreau was refurbished from 2008-2012. The NRU shut down in 2018 after 60 years. In 2015, Arthur McDonald won the Nobel Prize for neutrino research at the Sudbury Neutrino Observatory.

Today, Canada has 17 operable CANDU reactors (12.7 GWe), mostly in Ontario, providing ~14% of electricity. Focus has shifted to small modular reactors (SMRs), with provinces like Ontario, Saskatchewan, New Brunswick, and Alberta signing a 2019-2021 MOU for SMR development. Ontario Power Generation plans a 300 MWe BWRX-300 at Darlington by 2030, and SaskPower selected GE Hitachi for mid-2030s deployment. AECL restructured in 2011, selling its CANDU division to Candu Energy (now under AtkinsRéalis). Canada remains a leader in uranium production, radioisotopes, and nuclear exports.

Year(s)	Key Event/Milestone
1908	Ernest Rutherford wins Nobel for radioactive decay research at McGill University.
1930	Uranium discovered at Port Radium, NWT.
1944–1945	Chalk River Labs established; ZEEP reactor achieves first fission outside US.
1947	NRX reactor starts at Chalk River.
1952	AECL founded.
1957	NRU reactor operational.
1962	NPD reactor produces first electricity.
1967	Douglas Point, first full-scale CANDU, online.
1971–1973	Pickering A units make it world’s largest nuclear station.
1972	First CANDU export to India.
Late 1960s	SLOWPOKE reactor developed.
1980s	Point Lepreau and Gentilly-2 online.
1994	Bertram Brockhouse Nobel for Chalk River research.
2000	CNSC established.
2002	NWMO created for waste management.
2011	AECL sells CANDU division.
2015	Arthur McDonald Nobel for neutrino work; Ontario refurbishment program starts.
2018	NRU shuts down.
2019–2021	Provinces sign MOU for SMRs.
2023–2024	Darlington and Bruce refurbishments complete several units.
2025–2030s	SMR deployments planned at Darlington and elsewhere.

Nuclear Natural Resources

Canada’s uranium resources represent one of the country’s most significant natural advantages in the global energy landscape. Centered in the Athabasca Basin of northern Saskatchewan, these deposits are renowned for hosting the world’s highest-grade uranium ores, which are often 10 to 100 times richer than typical mined deposits elsewhere.

Advantages of Canadian Uranium Quality

The exceptional concentration and quality of Canadian uranium enables efficient, lower-impact extraction, positioning Canada as a premier supplier of nuclear fuel with strong economic, environmental, and reliability benefits.

• Efficiency and Economics: Less ore needs to be mined and processed for the same amount of uranium, lowering costs and making production more competitive.

• Environmental Benefits: Reduced mining footprint, less waste rock/tailings, and lower energy/water use per unit of uranium produced.

• Processing: Facilities like the McClean Lake mill (the only one capable of handling ultra-high-grade ore without dilution) and Key Lake mill are designed specifically for these rich ores, ensuring high recovery rates and purity in the final yellowcake (uranium concentrate).

• Global Standing: Canada remains the second-largest uranium producer (behind Kazakhstan), contributing ~13–24% of world supply in recent years, with its output prized for reliability, strict regulatory standards, and sustainability.

Canada’s uranium resources stand out not only for their exceptional high grades but also for the innovative, safety-focused mining techniques developed to extract them efficiently from deep, challenging deposits in the Athabasca Basin.

These attributes enhance operational efficiency, cost-competitiveness, and sustainability, reinforcing Canada’s position as a supplier of premium, reliably produced uranium in the global nuclear fuel supply chain.

Uranium Enrichment

Canada is a global leader in the front end of the nuclear fuel cycle, ranking among the world’s top producers and exporters of natural uranium (yellowcake, U₃O₈). However, it has never pursued large-scale commercial uranium enrichment domestically and continues to rely on foreign services for this step.

Most operating reactors worldwide are light-water designs, either Pressurized Water Reactors (PWRs) or Boiling Water Reactors (BWRs), accounting for roughly 80–85% of the global fleet. These require enriched uranium fuel, with U-235 concentrations increased from the natural level of ~0.7% to 3–5% (or higher for some advanced designs). Enrichment, the isotope separation process, occurs abroad for Canadian exports.

In contrast, Canada’s fleet of 17 operable reactors relies almost entirely on homegrown CANDU pressurized heavy-water reactors (PHWRs). These are uniquely designed to use natural (unenriched) uranium fuel, thanks to heavy water (deuterium oxide) as both moderator and coolant. This eliminates the need for enrichment, simplifies the fuel cycle, lowers costs, and reduces dependence on foreign suppliers for domestic power generation.

Historical and Technical Reasons

This CANDU advantage, developed in the 1950s–1960s, has fundamentally shaped Canada’s approach. With no domestic demand for enriched fuel, there has been little incentive to build enrichment facilities. Canada instead excels in upstream activities: high-grade mining (especially in Saskatchewan), refining (Blind River, Ontario), and conversion to UF₆ (Port Hope, Ontario) or direct UO₂ fabrication for CANDU fuel. Enrichment is outsourced to partners such as Urenco (Europe/USA) or others.

Canada’s strong commitment to nuclear non-proliferation under the NPT and IAEA safeguards has also played a key role. Enrichment is a dual-use technology (capable of producing weapons-grade material at high levels), and avoiding it has aligned with a focus on peaceful uses, reinforcing Canada’s reputation without any outright legal prohibition (civilian enrichment is allowed up to <20% U-235).

Economically, enrichment plants demand massive capital investment (billions of dollars), specialized technology licensing (e.g., centrifuges), and a large, sustained market to justify costs. With reliable foreign supply and no domestic need, building capacity has not been viable. Most Canadian uranium is exported as UF₆ for foreign enrichment, capturing value abroad rather than at home.

Shifting Context and Recent Discussions

The Canadian nuclear landscape is evolving with plans for new reactors, particularly small modular reactors (SMRs) and light-water designs such as the GE-Hitachi BWRX-300 at Darlington. These require enriched fuel, including high-assay low-enriched uranium (HALEU, 5–20% U-235) for many advanced concepts, creating growing reliance on foreign enrichers (primarily USA and Europe, with historical exposure to Russia/China in global chains).

Recent analyses and policy discussions (2024–2026) highlight increasing concerns over:

• Geopolitical vulnerabilities and supply chain security, especially amid efforts to reduce dependence on non-allied sources.

• Energy security for provinces advancing SMR projects (e.g., Ontario, Saskatchewan).

• Economic potential to capture more value from uranium exports by adding domestic enrichment capacity.

While proposals exist for partnerships or new facilities, and some experts advocate clearer government policies to address fuel cycle gaps, no firm commitment to domestic enrichment has emerged. Past efforts (e.g., around 2006) faced challenges, and current focus leans toward allied backstop mechanisms and international cooperation rather than standalone Canadian plants.

Nuclear Waste Management and Storage

Canada manages nuclear waste primarily through the Nuclear Waste Management Organization (NWMO), a not-for-profit established in 2002 under the Nuclear Fuel Waste Act. The NWMO implements Adaptive Phased Management (APM), focusing on long-term containment of used nuclear fuel and high-level waste in a deep geological repository (DGR). In 2023, its mandate expanded to include intermediate-level and non-fuel high-level waste.

Current Efforts

• Site Selection and Regulatory Progress: In November 2024, the NWMO selected the Wabigoon Lake Ojibway Nation-Ignace area in northwestern Ontario as the host site, following a consent-based process with 22 initial communities, technical studies, borehole drilling, and a 2024 “Confidence in Safety” report. On January 5, 2026, the NWMO submitted the Initial Project Description to the Impact Assessment Agency of Canada (IAAC) and Canadian Nuclear Safety Commission (CNSC), starting the integrated impact assessment and licensing process. Public comments are invited until February 4, 2026.

• Design and Planning: Conceptual designs continue, with five companies (including WSP Canada Inc. and Peter Kiewit Sons ULC) selected in May 2025 for engineering, construction, and environmental work. The DGR will permanently store ~5.9 million used fuel bundles, shifting from interim onsite storage at reactor sites.

• Other Initiatives: Ontario Power Generation pursues a separate DGR for low- and intermediate-level waste at the Bruce Nuclear site (under CNSC review). Transportation from interim sites to the DGR is planned under APM.

All used nuclear fuel remains safely stored in licensed interim facilities at nuclear plants and research sites; the DGR provides the long-term solution.

Unique Aspects of the Proposed DGR

Located 650–800 meters underground in stable crystalline rock near the selected site, the facility emphasizes passive safety and isolation over geological timescales (millions of years), with a compact underground footprint (~2 × 3 km) and minimal surface impact.

• Multiple-Barrier System: Used fuel in corrosion-resistant containers, surrounded by swelling bentonite clay buffers and backfill in horizontal rooms—engineered and natural barriers provide redundant protection.

• Adaptive Design: Flexible, iterative approach incorporating site data, studies, and feedback; construction uses controlled methods suited to the rock.

• Monitoring and Retrievability: Real-time tracking of groundwater, radiation, air, and risks during construction, operation, and extended post-placement monitoring (decades); retrievability possible, though permanent isolation is the goal.

• Community and Indigenous Focus: Consent-based siting requires willing hosts; strong partnerships with Indigenous communities (e.g., Wabigoon Lake Ojibway Nation), integration of Indigenous Knowledge, economic benefits, and ethical stewardship for future generations.

• Public Engagement: Includes a Centre of Expertise with viewing galleries for transparency and education.

Modeled on Finland’s and Sweden’s repositories but tailored to Canada’s inventory and geology, the DGR is projected to become operational in the 2040s, marking a shift to permanent geological isolation.

The Future of the Canadian Nuclear Industry

The Canadian nuclear industry stands at a pivotal juncture, building on its storied legacy of innovation, safety, and international responsibility to address the nation’s evolving energy needs. As Canada confronts rising electricity demand driven by electrification, population growth, data centers, and artificial intelligence technologies, potentially doubling by mid-century, nuclear power offers a reliable, low-carbon solution that aligns with net-zero ambitions by 2050.

Near-term momentum is centered on Small Modular Reactors (SMRs), marking an evolution beyond the traditional CANDU fleet. Ontario Power Generation’s Darlington New Nuclear Project, now licensed for construction of the GE Hitachi BWRX-300, has moved from concept to execution, with the first 300 MWe unit targeted for grid connection by the end of the decade and additional units planned. In parallel, major refurbishments at Bruce and Darlington continue to anchor system reliability and extend the value of existing assets.

Across the country, provinces are advancing at different speeds but with increasing alignment. Saskatchewan is progressing toward a BWRX-300 in the Estevan region in the 2030s, New Brunswick is advancing advanced reactor options at Point Lepreau, and Alberta is exploring pathways through recent MOUs. Interprovincial collaboration, along with off-grid and remote applications, underscores the growing role of nuclear beyond traditional baseload generation.

Equally critical is Canada’s approach to responsible waste management. The Nuclear Waste Management Organization’s Adaptive Phased Management program has entered a decisive phase, with the deep geological repository project now in federal impact assessment and licensing. Designed for long-term isolation in stable crystalline rock and developed in partnership with the Wabigoon Lake Ojibway Nation, the project reflects Canada’s commitment to technical rigour, transparency, and reconciliation as the industry looks toward operations in the 2040s.

Canada’s position is further strengthened by its high-grade uranium resources in the Athabasca Basin, providing a strategic advantage as global demand for nuclear fuel accelerates. While discussions around domestic enrichment and HALEU supply continue, Canada remains firmly embedded within allied, non-proliferation-aligned supply chains.

Taken together, these developments point to a nuclear sector that is no longer simply maintaining legacy capacity, but actively redefining its role in Canada’s energy system. With pragmatic policy, sustained investment, and continued collaboration across governments, Indigenous partners, and industry, nuclear energy is poised to deliver emissions reductions, energy security, and durable economic value, cementing its role as a cornerstone of Canada’s resilient, sovereign, and sustainable energy future.