The 5 Countries Closest to Deploying a Commercial SMR
The global race to build the first grid-scale small modular reactor is no longer theoretical — these five nations are doing it right now.
The starting pistol has fired. After decades of conference room promises and engineering whitepapers, small modular reactors are being bolted together with real steel and real money. Governments that once hedged their bets are writing billion-dollar cheques. Regulators are clearing paths. Construction crews are showing up. The SMR race, which looked like a distant fantasy for most of the 2010s, is now a live competition — and the gap between the frontrunners and everyone else is widening fast. 🏁
So which countries are genuinely close? Not close in the “we filed some paperwork” sense, but close in the “concrete is being poured, licensing is nearly done, fuel loading is imminent” sense? The honest answer narrows the field considerably. What follows is a country-by-country look at who’s actually in contention — and a candid read on where each one really stands.
China: the race is over, and China won
Let’s get the uncomfortable news out of the way first. While the Western world has been debating, piloting, and announcing, China has been building. ⚡
The Linglong One — officially designated the ACP100, a 125 MWe integrated pressurized water reactor developed by China National Nuclear Corporation — is not a concept. It is a reactor that completed cold functional testing in October 2025, passed its non-nuclear turbine run test in December 2025, and is targeting commercial operation in the first half of 2026. According to officials from CNNC’s research arm, China will start commercial operation of the Linglong One in the first half of 2026. That makes it the world’s first commercial land-based SMR — full stop. 🌍
The numbers matter here. Key facts about Linglong One:
Located at the Changjiang site on Hainan Island, a province that already hosts two operating CNP600 reactors
First concrete poured July 2021; the 58-month construction schedule has held
Capable of producing 1 billion kilowatt-hours annually, enough for 526,000 households
First SMR in the world to pass an IAEA safety review, back in 2016
Designed for electricity, heating, steam production, and seawater desalination
The Nuclear Energy Agency’s SMR Dashboard listed Linglong One as “under construction” with commissioning set for 2026, and analysts noted that the most critical phases of civil engineering, equipment installation, and safety validation were completed. This isn’t a press release. This is a reactor progressing through hot trials toward fuel loading.
What makes China’s position particularly striking is the export ambition behind it. CNNC is actively pitching the ACP100 design to partners in Indonesia, Thailand, Malaysia, and Saudi Arabia under the Belt and Road Initiative. Every month the Linglong One operates, that pitch gets more credible. The 58-month build timeline — if it holds through commercial operation — becomes the benchmark that every Western developer will be measured against for the next decade.
Do you think the West has a realistic path to catching China’s head start on commercial SMR deployment? That’s the question the next four entries on this list are really trying to answer. 🔬
Canada: the West’s best shot, and it’s genuinely exciting
If you’re looking for a reason to be optimistic about the Western SMR program, look north. Canada is the only G7 nation with a grid-scale SMR under active construction — and it’s moving with a speed that should embarrass certain other English-speaking countries on this list.
Ontario Power Generation received its construction licence from Canada’s Nuclear Safety Commission in April 2025 and broke ground in May. The project uses GE Vernova Hitachi’s BWRX-300, a 300 MWe boiling water reactor that GVH describes as a 10th-generation design built on decades of real-world BWR experience. Construction began in May 2025 at Ontario’s Darlington New Nuclear Project site, with the first BWRX-300 unit scheduled to be operational in 2030. 🚀
The pacing here is genuinely impressive. As recently as March 30, 2026, Canada’s nuclear safety commission lifted the first regulatory hold point for the Darlington New Nuclear Project — the milestone relating to installation of the reactor building foundation — and OPG also applied in March 2026 for a 20-year operating licence. That’s not paper-shuffling; that’s a reactor whose foundation is in the ground and whose operator is already thinking about how it runs for the next two decades.
Key numbers on the Darlington project:
Four BWRX-300 units planned in total, with combined capacity of 1,200 MW — enough for 1.2 million homes
Total estimated cost of CAD 20.9 billion across all four units, including contingency
The Canadian Growth Fund and Building Ontario Fund have committed up to CAD 3 billion to de-risk the first-of-a-kind build
GE Vernova confirmed that key components including the reactor pressure vessel are in manufacturing
The tunnel boring machine, nicknamed “Harriett Brooks” after Canada’s first female nuclear physicist, arrived from Germany ahead of drilling the condenser cooling water tunnel
The BWRX-300 design has also completed Step 2 of the Generic Design Assessment in the UK, meaning its regulatory journey isn’t limited to North America. Tennessee Valley Authority submitted a construction permit application to the NRC for a BWRX-300 at its Clinch River site in Oak Ridge, Tennessee in May 2025, and Poland’s OSGE has selected it for the country’s first SMR at Włocławek. Darlington is, in effect, the first domino in a global deployment chain. If OPG delivers on time and on budget, the ripple effects across a dozen planned projects will be enormous. That’s a lot of pressure on one project site northeast of Toronto — and the people building it seem to know it.
United Kingdom: big ambitions, tight timeline
The UK announced its SMR ambitions so many times over the past five years that a healthy level of skepticism is warranted. But something actually happened in November 2025: the government selected Wylfa on the island of Anglesey in North Wales as the site for Britain’s first three SMRs, backed by a £2.5 billion government commitment, with Rolls-Royce SMR as the preferred developer. 💡
Great British Energy–Nuclear plans to begin site activity in 2026, with the ambition for Wylfa’s SMRs to be supplying power to the grid from the mid-2030s. The three initial units, each rated at 470 MWe, would deliver a combined 1,440 MW — enough for roughly 1.5 million homes. The site has a nuclear heritage dating back to a Magnox station that operated from 1971 to 2015, which means existing infrastructure and a community that’s already familiar with nuclear.
What makes the UK placement on this list credible rather than aspirational:
Rolls-Royce SMR’s design is in Step 3 of the UK Generic Design Assessment, the final stage before Design Acceptance Confirmation from the Office for Nuclear Regulation
Step 3 is expected to be completed in August 2026, with a total GDA duration of 53 months
If licensing completes on schedule, first concrete at Wylfa could happen as early as 2027, with a four-year construction timeline pointing to a possible operational date around 2031-2032
The Czech utility ČEZ owns a 20% stake in Rolls-Royce SMR and signed an Early Works Agreement in July 2025 to advance deployment at the Temelín site — giving the design its first export customer before UK completion
The UK’s track record on large-scale energy infrastructure — Hinkley Point C, anyone? — gives legitimate cause for caution. First-of-a-kind reactor projects are notoriously prone to delays and cost overruns, and Rolls-Royce SMR is still a developer without a completed build to its name. The mid-2030s target is plausible. It is not guaranteed.
That said, the political commitment looks firmer than at any previous moment. The £2.5 billion in government funding is real, the site is selected, the regulatory process is in its final stage, and there’s a named investor (Qatar’s sovereign wealth fund is among Rolls-Royce SMR’s backers). That’s meaningfully more concrete than most SMR programs globally. Pun intended. 🏗️
United States: messy, loud, and moving faster than it looks
The US SMR story is chaotic by design. There’s no single national champion, no coordinated timeline, and no shortage of skeptics pointing out that NuScale’s high-profile collapse on the Utah Associated Municipal Power Systems project in 2023 was a significant setback for the whole sector. All of that is true. And yet, the US is building SMRs — more than one, from more than one developer. 📈
The clearest case is TerraPower’s Natrium reactor in Kemmerer, Wyoming. Founded by Bill Gates, TerraPower broke ground in June 2024 on its 345 MWe sodium-cooled fast reactor adjacent to a retiring PacifiCorp coal plant. The design includes molten salt thermal storage that can peak to 500 MWe — a flexibility no light-water SMR offers. NRC approval is expected by December 2026, with the reactor targeting operation by 2030. This is not a paper project; the site is active, non-nuclear construction is underway, and TerraPower has committed funding exceeding $830 million in private capital alongside up to $2 billion in DOE support.
Beyond TerraPower, consider what else is moving:
Kairos Power’s Hermes test reactor in Oak Ridge, Tennessee — a fluoride salt-cooled design — is the only NRC-licensed SMR that has actually broken ground for construction
Tennessee Valley Authority submitted a construction permit application to the NRC for a BWRX-300 at Clinch River in May 2025, backed by a $400 million DOE grant
X-energy, together with Amazon, Korea Hydro & Nuclear Power, and Doosan Enerbility, announced a strategic partnership in 2025 to deploy its Xe-100 reactors with up to $50 billion in mobilised investment
The DOE’s Nuclear Reactor Pilot Program selected ten advanced reactor projects for accelerated development — a programme designed to produce operating demonstrations by the mid-2020s
What the US has, and consistently underestimates, is the deepest private capital market in the world. The hyperscalers — Amazon, Google, Microsoft, Meta — are not just writing cheques for nuclear power purchase agreements. They are creating revenue certainty that makes SMR project finance viable in a way it wasn’t five years ago. That demand signal matters. It’s why the US SMR market, despite its regulatory complexity and first-mover failures, remains one of the most important in the world. 💊
South Korea: disciplined, credentialed, and playing the long game
South Korea doesn’t get the breathless coverage of the other four countries on this list. It should. 🧬
The country has one of the world’s most proven nuclear operating records — 26 reactors in commercial operation, the Barakah project in the UAE delivered on time and on budget under KEPCO’s leadership — and it’s applying that same methodical discipline to its SMR program. Two designs are in active development:
The i-SMR (Innovative Small Modular Reactor), a 170 MWe integral PWR developed by a consortium led by KHNP and the Korea Atomic Energy Research Institute. It completed its basic design phase in 2025, submitted a Standard Design Approval application to the Nuclear Safety and Security Commission in early 2026, and is targeting SDA by 2028 with commercial operation in 2035
The SMART100, a 110 MWe design that received standard design approval from South Korea’s NSSC in September 2024 and has since received Approval in Principle from the American Bureau of Shipping for a floating nuclear power platform — a first for any SMR design of its type
South Korea’s National Assembly passed a Special Act on the Promotion and Support of Small Modular Reactor Development in February 2026, with the Ministry of Science and ICT planning to invest KRW 1,200 billion by 2030 in core technology for three domestically developed SMR reactor types.
Key developments in South Korea’s program:
KHNP signed an MOU with Daegu Metropolitan City to build a 680 MWe plant using four i-SMR modules at a high-tech industrial complex, targeting commercial development from 2033
Samsung Heavy Industries received ABS Approval in Principle for a floating marine nuclear power platform using SMART100 reactors
Major industrials including Doosan Enerbility, Samsung C&T, and HD Hyundai are all embedded in global BWRX-300 and other SMR supply chains, giving the country manufacturing leverage beyond its domestic designs
South Korea is co-developing SMR technology with Saudi Arabia under a formal government agreement targeting a SMART deployment in the Kingdom
South Korea’s 2035 commercial operation target for the i-SMR is later than the others on this list — but the design work is rigorous, the regulatory pathway is clear, and the industrial base to deliver it is already in place. No other country on this list has Korea’s combination of nuclear manufacturing depth and operating experience. When the i-SMR gets built, it will probably be on time.
What this all means
The five-country picture tells a clear story. China has lapped the field. The Linglong One’s H1 2026 commercial operation, if it delivers as planned, means the world’s first commercial land-based SMR will be Chinese — and will have been built in 58 months. That’s a benchmark Western programs are going to spend the rest of the decade trying to match.
Canada is the Western leader, with actual construction underway at Darlington and a 2030 target that looks credible given current progress. The UK has selected a site, a developer, and committed real money — with grid connection in the mid-2030s a plausible if not guaranteed outcome. The United States is building multiple projects through multiple developers, with private capital driving a pace that government-led programs can’t match. And South Korea is doing what it always does: moving carefully, building on proven engineering, and preparing to deliver.
The World Nuclear Association’s SMR Global Project Tracker puts the total number of designs in development at over 127 as of 2025, but the gap between “design in development” and “reactor under construction” is vast. These five countries have crossed it — or are crossing it now. Everyone else is still on the other side.
The question worth sitting with: if the first Western commercial SMR comes online in 2030 at Darlington, that’s four-plus years after China’s Linglong One. Is that gap recoverable in terms of export market position, technology credibility, and geopolitical influence? What do you think? ☢️