Canada’s AtkinsRéalis Group has submitted a Notice of Intent to the US Nuclear Regulatory Commission (NRC) to begin the licensing process for its Candu reactor technology in the United States. The company is leveraging NRC’s new Part 53 regulatory framework, aiming to secure an accelerated 18-month licensing decision timeline.
The filing represents a key milestone in the company’s strategy to deploy proven large-scale nuclear power in support of significant US electricity demand driven by data centres, artificial intelligence, advanced manufacturing and broader electrification.
“As the United States enters a new chapter in its civilian nuclear programme, AtkinsRéalis is uniquely positioned, as the steward of Candu technology, to help advance the country’s ambitious energy policy through proven, low-cost reactor technology with a world-class reputation,” said AtkinsRéalis President and CEO Ian L Edwards. “This Notice of Intent marks a critical milestone in the development of Candu’s international market. It’s also the first step in a process that supports our ambition to provide the US with the reliable, affordable and safe large-scale nuclear power that is central to providing energy security and creating investment, jobs and economic opportunity in the country.”
The company is engaging US utilities, state governments and prospective anchor power purchasers, including hyperscale data centre operators and large industrial users, to evaluate potential deployment opportunities. AtkinsRéalis is focusing on existing nuclear sites and jurisdictions with supportive nuclear policy frameworks to reduce siting risk and accelerate timelines.
Candu technology has a good track record with 34 units built globally and nearly 1,000 reactor-years of experience. Candu reactors have operated for decades in Canada, Romania, Argentina, Korea, and China. Historically, Candu builds (like those in Qinshan, China) have a reputation for being delivered on budget and on schedule.
The Enhanced Candu-6 design is a 700+ MWe pressurised heavy water reactor that uses natural uranium fuel and online refuelling, enabling continuous operation without shutdown. The Candu has two fully independent, rapid-acting shutdown systems that do not require electrical power – gravity-dropped shutoff rods and high-pressure liquid poison injection. Furthermore, the massive, cool low-pressure moderator tank acts as an inherent heat sink to slow down any potential accident progression.
Candu reactors can also co-produce crucial medical radioisotopes, such as Cobalt-60, which supplies 50% of the global market for cancer detection and sterilisation equipment.
The Candu design avoids the supply issues that plague light water reactors such as the AP1000, which have to rely on just a few ultra-heavy foundries globally capable of forging their massive pressure vessels. The Candu distributes its pressure boundary across hundreds of small tubes instead of containing it within one massive steel tank.
Historically, Canada chose this solution after post-WWII politics cut them off from uranium enrichment technology. Because they had to use natural uranium, they required a heavy-water moderator, which naturally demands a much larger physical core volume. Canada lacked the heavy industrial foundries required to forge a colossal, thick-walled pressure vessel of that size. Rather than ceding industrial sovereignty, Canadian engineers reinvented the reactor core.
The Candu dispenses with the giant pressure vessel entirely. Instead, the core consists of an array of hundreds of narrow, horizontal zirconium-alloy pressure tubes (typically 380 to 480 depending on the model). Because a narrow 10-centimetre tube has a radically smaller surface area, it can easily contain the exact same high coolant pressures with a wall thickness of just 4.2 millimetres, compared with the 20+ centimetre thick steel walls required by an AP1000.
Because the intense pressure is entirely isolated inside the individual tubes, the main outer reactor vessel – the Calandria – does not experience high structural stress. The Calandria is simply a large, stainless steel tank oriented horizontally that holds the heavy-water moderator at just slightly above atmospheric pressure. It operates under low pressure and can be manufactured using standard industrial steel plates, conventional rolling machines, and routine high-quality welding. Any tier-one domestic manufacturing shipyard or heavy industrial fabricator can construct a Calandria, bypassing specialized global nuclear foundries.
The 380-480 pressure tubes inside an Enhanced Candu-6 are identical. Instead of waiting years for a single bespoke component to arrive from overseas, a utility can contract local standard extrusion facilities to mass-produce the zirconium tubes on a continuous assembly line.
In light-water construction, the reactor containment building and the cooling loops cannot be completed until the RPV is installed. With a Candu, civil construction can progress uninterrupted. The empty Calandria shell is installed early, and the identical pressure tubes can be slid into place manually or systematically at any later phase
The Candu supply chain behaves more like an automotive or aerospace assembly line than a boutique megaproject. Rather than risking the entire project timeline for a few hyper-specialised global suppliers, AtkinsRéalis can source components across a vast, diversified network of tier-two domestic and international manufacturers. If a single supplier of zirconium tubes falls behind, orders can immediately be reallocated to an alternative vendor. The Canadian nuclear supply chain alone is composed of 250 companies and employs 90,000 professionals.
“Candu reactors strengthen US energy security in a very tangible way as they use natural uranium and do not require enrichment, ultimately reducing reliance on foreign enrichment services,” said Joe St Julian, President, Nuclear, AtkinsRéalis. “That fuel flexibility, combined with decades of on time and on budget performance, will give the United States greater control over its nuclear fuel supply chain, which is of paramount importance in the current geopolitical climate, while delivering dependable, low-carbon baseload power.”
