On a coastal stretch of Hainan island, where China’s southernmost nuclear power station already feeds electricity into the provincial grid, a compact reactor called Linglong One is nearing a milestone that the global nuclear industry has chased for more than a decade. Built by the China National Nuclear Corporation (CNNC) at the Changjiang Nuclear Power Plant, the ACP100 reactor is on track to become the world’s first land-based commercial small modular reactor to enter operation, with CNNC targeting grid connection in 2026.
If that schedule holds, China will have beaten every Western competitor to the punch, delivering a working commercial SMR while rival projects in the United States, the United Kingdom, and Canada remain stuck in licensing reviews or have stalled outright.
From blueprint to construction site
Construction of the Linglong One officially began on July 13, 2021, after China’s National Nuclear Safety Administration (NNSA) issued the required construction permit. The NNSA, which operates under the Ministry of Ecology and Environment, described the project in its own public announcement as the “world’s first commercial SMR project on land.” In China’s nuclear governance system, that permit comes only after regulators have reviewed detailed safety analyses, seismic assessments, environmental impact studies, and the full reactor design package.
The choice of Changjiang was strategic. The site already hosts two operating CNP-600 pressurized water reactors and has additional large units under construction, meaning the Linglong One can tap into existing grid connections, cooling water infrastructure, emergency planning zones, and trained operational staff. Rather than building from scratch on a greenfield site, CNNC embedded its flagship SMR inside a proven nuclear campus.
What the ACP100 actually is
The ACP100 is an integral pressurized water reactor, meaning its steam generators sit inside the reactor pressure vessel rather than in separate external loops. That design choice eliminates large-bore piping between major components, which removes one of the most significant accident pathways in conventional nuclear plants: a large-break loss-of-coolant accident.
The reactor is designed to produce approximately 125 megawatts of thermal energy and deliver around 125 megawatts of electrical output to the grid. That is roughly one-eighth the capacity of a typical large reactor, but the smaller footprint is the point. SMRs are intended for island grids, remote industrial sites, and countries whose electrical systems cannot absorb the output of a full-scale nuclear station. Hainan’s relatively isolated grid makes it a fitting proving ground.
Before construction began, the ACP100 design had already undergone international scrutiny. In 2016, the International Atomic Energy Agency completed a Generic Reactor Safety Review (GRSR) of the design, making it the first SMR in the world to pass that assessment. The GRSR is not a regulatory approval, but it signals that an independent international body found no fundamental safety obstacles in the concept, lending the project a layer of credibility beyond Chinese domestic review.
Where the project stands now
As of mid-2026, CNNC’s publicly stated timeline targets initial operations this year. Between the 2021 construction start and grid connection, the reactor must clear a series of regulatory gates familiar to every nuclear project worldwide: cold hydrostatic testing of the primary circuit, hot functional tests to verify system behavior at operating temperatures and pressures, fuel loading authorization from the NNSA, initial criticality (the first self-sustaining chain reaction), and a graduated power ascension program before reaching full commercial output.
Chinese state media and CNNC corporate communications have reported progress at the Changjiang site, including installation of major reactor vessel components. However, the NNSA has not published a detailed, independently verifiable commissioning schedule with specific dates for each intermediate milestone. Readers should treat the 2026 target as the operator’s stated goal rather than a confirmed regulatory commitment, recognizing that nuclear construction projects worldwide frequently encounter delays during the final testing and commissioning phases.
The global SMR race and why it matters
China’s progress with Linglong One stands in sharp contrast to the struggles facing SMR developers elsewhere. In the United States, NuScale Power’s SMR design became the first to receive design certification from the Nuclear Regulatory Commission in January 2023, but its flagship deployment project with the Utah Associated Municipal Power Systems (UAMPS) was canceled later that year after projected costs roughly doubled and customer utilities pulled out. NuScale is now pursuing alternative deployment sites, but no U.S. commercial SMR is under construction.
In the United Kingdom, Rolls-Royce SMR is progressing through the Generic Design Assessment process with regulators but has not yet broken ground. South Korea’s KAERI has developed the SMART reactor design, which passed an IAEA design review, but has no domestic construction commitment. Canada’s regulatory body is reviewing several SMR concepts from multiple vendors, with Ontario Power Generation’s Darlington site identified as a potential location, though construction timelines remain fluid.
Russia offers the closest operational comparison. The Akademik Lomonosov, a floating nuclear power plant with two KLT-40S reactors, began supplying electricity to the remote town of Pevek in 2020. But that is a barge-mounted system designed for Arctic conditions, not a land-based commercial SMR in the mold that most countries are pursuing. China’s Linglong One, if it reaches the grid as planned, would be the first to demonstrate the land-based commercial model that dozens of governments have identified as a potential tool for decarbonization and energy access.
Export ambitions and open questions
CNNC has signaled interest in marketing the ACP100 to countries involved in China’s Belt and Road Initiative, particularly nations with small or fragmented grids where a 125-megawatt reactor could be a practical fit. Pakistan, which already operates Chinese-designed large reactors, is frequently cited as a potential early customer.
But significant hurdles remain. No foreign nuclear regulator has publicly disclosed acceptance of a detailed ACP100 safety submission for site-specific licensing. Export of nuclear technology involves not just engineering but also international safeguards agreements, fuel supply arrangements, waste management commitments, and geopolitical considerations that can slow or block deals regardless of technical readiness. Until a foreign regulator formally begins a licensing review of the ACP100, export prospects remain aspirational.
Cost is another area where hard data is scarce. CNNC has not published detailed construction cost figures for the Linglong One in a format comparable to Western regulatory filings. Whether the project can demonstrate the economic competitiveness that SMR advocates have long promised, particularly against falling costs for solar, wind, and battery storage, will depend on data that only emerges after the reactor operates for a sustained period.
What to watch as Linglong One approaches the grid
The gap between “under construction” and “operational” is where nuclear projects are most vulnerable. Globally, reactors that broke ground on schedule have still faced years of delays during testing and commissioning. France’s Flamanville-3 EPR, originally expected to start in 2012, did not achieve first criticality until 2024. The Vogtle Units 3 and 4 in Georgia, the only new nuclear reactors built in the United States in a generation, came online years late and billions over budget.
For the Linglong One, the key signals to watch are NNSA announcements on fuel loading authorization and initial criticality. Those are the regulatory milestones that separate a construction project from a functioning reactor. CNNC’s stated 2026 timeline puts those steps in the near term, and confirmation from the Chinese regulator, rather than corporate press releases or secondary news reports, will be the most reliable indicator of whether the world’s first commercial SMR has actually crossed the finish line.
If it does, the implications extend well beyond Hainan. A working commercial SMR would validate a technology category that has absorbed billions in public and private investment worldwide but has yet to produce a single kilowatt-hour of commercially sold electricity from a land-based unit. For governments weighing their energy options, for utilities evaluating nuclear as a complement to renewables, and for competing SMR developers racing to prove their own designs, Linglong One’s performance in its first months of operation will set the benchmark.
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*This article was researched with the help of AI, with human editors creating the final content.
