China has quietly crossed a new nuclear threshold, bringing the second reactor at its Zhangzhou Nuclear Power Plant into full commercial service and cementing the site as the largest operating hub for its Hualong One technology. The move caps Phase I of a project designed to anchor the country’s coastal power grid with low carbon baseload electricity while showcasing a homegrown reactor design to the world.
Unit 2’s start of commercial operation at the Zhangzhou site in Fujian Province is more than a technical milestone, it is a signal of how aggressively the country is leaning on nuclear power to meet surging demand and climate goals at the same time. With two reactors now running and four more planned, the complex is emerging as a central pillar of China’s long term energy strategy.
Inside Zhangzhou’s Phase I milestone
At the heart of the story is Unit 2 of the China National Nuclear Corporation’s Zhangzhou Nuclear Power Plant in east China’s Fujian Province, which has now completed the final checks needed to move into full commercial operation. The unit finished a rigorous 168 hours of full power assessment, a standard proving run that tests every major system under continuous load before operators declare the reactor ready for long term service. Clearing that hurdle means the second power unit can now run as part of the national grid rather than as a test installation.
Phase I at Zhangzhou consists of two Hualong One reactors, referred to in official documents as Units 1 and 2, both developed and built by China National Nuclear Corporation. With Unit 2 now in commercial operation, the project’s first construction phase is formally complete, turning what had been a massive building site into a functioning industrial asset. The Zhangzhou Nuclear Power Plant is designed to eventually host six Hualong One units, and the first pair already delivers billions of kilowatt hours of clean electricity annually to Fujian and neighboring provinces, according to project descriptions linked to the Phase I completion.
How Unit 2 was brought online
Unit 2’s journey from construction site to operating reactor followed a carefully sequenced path that illustrates how China now standardizes its nuclear rollout. Fuel loading at the second nuclear power unit in Zhangzhou began after civil works and major equipment installation were complete, a step captured in official footage that highlighted technicians overseeing the insertion of fuel assemblies into the core. That process, described in coverage of how Fuel loading begins at the 2nd unit, marked the transition from construction to commissioning.
Once fuel was in place, operators moved through low power tests, grid connection, and then the extended full power trial that culminated in the 168 hour assessment. Reports from ZHANGZHOU note that, after this continuous run, the second power unit was judged to have met all technical indicators required for commercial operation, confirming that both the reactor core and auxiliary systems performed as designed. The formal declaration that the unit had passed its assessment effectively flipped Zhangzhou Unit 2 from a project in testing to a permanent part of the country’s power system.
Why Zhangzhou is now the world’s biggest Hualong One hub
With both initial reactors now in service, Zhangzhou has become the largest operating base for the Hualong One design, the flagship third generation reactor developed by China National Nuclear Corporation. Official descriptions of the site emphasize that Zhangzhou Nuclear Power Plant is planned to host six Hualong One units in total, making it the world’s largest Hualong One nuclear power base once all phases are complete. The completion of Phase I, with Units 1 and 2 online, is presented as the first step toward that six unit configuration in Fujian Province, a status highlighted in reports on the world’s largest Hualong One nuclear power base.
The scale matters because Hualong One is marketed as a standard, repeatable design that can be deployed in clusters, lowering costs and simplifying operations. Concentrating six identical units at Zhangzhou allows China National Nuclear Corporation to build a deep bench of operating experience, from shared maintenance teams to common spare parts, while delivering a large block of low carbon power to the coastal grid. The project’s backers frame this as proof that China can not only design advanced reactors but also deploy them at industrial scale, reinforcing the country’s broader nuclear ambitions that are visible in national level overviews of China and its energy strategy.
Unit 1’s earlier debut set the stage
Unit 2’s smooth start up was made possible in part because Zhangzhou Unit 1 had already blazed the trail into commercial service. Industry reports note that Zhangzhou 1 entered commercial operation on 1 January of the same year, giving operators months of experience with the site’s layout, grid connections, and Hualong One specific procedures before they repeated the process with the second reactor. That first unit’s commissioning, described in detail in coverage of how Zhangzhou 1 entered commercial operation, effectively turned Zhangzhou into a live plant while Unit 2 was still in testing. By the time Unit 2 began its own fuel loading and grid connection steps, engineers could draw directly on lessons from Unit 1’s start up, from fine tuning control room procedures to coordinating with regional grid operators. That experience likely contributed to the second unit’s ability to pass its 168 hour full power run without major incident, a performance that project backers point to as evidence of the Hualong One design’s maturity. The staggered commissioning also meant that Zhangzhou was already contributing clean electricity to the grid while Phase I was still being completed, a dynamic that helped the site reach the status of a fully fledged Hualong One base as soon as Unit 2’s full power assessment wrapped up.
From grid connection to commercial power
The path from first grid connection to full commercial operation at Zhangzhou mirrors a pattern that has become familiar across China’s nuclear fleet. Earlier, when another new Hualong One unit at the same site was first synchronized with the grid, officials highlighted that the successful launch provided a massive new source of carbon free electricity capable of supplying millions of homes once it reached full power. That moment, described in reports on how China has connected a new Hualong One unit to the grid after fuel loading in October 2025, marked the beginning of a trial period in which the reactor’s output was gradually increased.
Commercial operation only begins after that trial period proves the unit can run safely and reliably at full power, which is where the 168 hour continuous assessment comes in for Zhangzhou Unit 2. Passing that test allowed operators to declare that the second unit had cleared the final technical hurdle required for commercial operation, a status that unlocks its full contribution to the grid and revenue stream. The same pattern applied to Unit 1, which moved from first grid connection to commercial service over a similar sequence of tests, as noted in accounts of how Zhangzhou progressed through commissioning.
Part of a much bigger nuclear build out
Zhangzhou’s rise as a nuclear hub is not an isolated story, it is one node in a much larger expansion of atomic power across the country. National performance reports show that China had 32 reactors under construction as of 31 July 2025, totaling 34 GWe of capacity, a figure that underscores how many projects are moving in parallel. Those same overviews note that, in October 2024, the country’s first CAP1000 unit entered service and that other advanced projects such as Shidaowan Phase II and Xiapu Phase I are also underway, details captured in the China mainland performance report.
Policy decisions taken earlier in the decade laid the groundwork for this surge. A notable example is the decision described under the heading China Inks Approval for Four New Reactors, which detailed how authorities approved the construction of four new nuclear power plants in Fujian province and Liaoning province. Those approvals, combined with ongoing projects like Zhangzhou, signal a deliberate strategy to build a dense network of reactors along the coast and in industrial regions, using designs such as Hualong One to standardize the fleet.
What makes Hualong One strategically important
Hualong One is more than just another reactor type in the global mix, it is a symbol of technological self reliance for China National Nuclear Corporation and a platform for export ambitions. Technical summaries emphasize that the design is a third generation pressurized water reactor with fully independent intellectual property rights held by Chinese entities, a point highlighted in industry digests that describe how China’s Zhangzhou Nuclear Unit 2 represents a milestone for this indigenous technology. That independence matters in a world where nuclear projects can be entangled in export controls and geopolitical rivalries.
Deploying multiple Hualong One units at a single site like Zhangzhou allows engineers to refine the design in real operating conditions, from fuel management to digital control systems, while building a track record that can be shown to potential overseas customers. It also reduces reliance on foreign vendors for critical components and know how, giving China National Nuclear Corp more leverage in negotiations and more flexibility in how it finances and structures future projects. The fact that Zhangzhou is now the world’s largest Hualong One base, with Unit 2 in commercial operation and four more reactors planned at the site, underscores how central this design has become to the country’s nuclear identity.
How Zhangzhou compares with other “world’s largest” nuclear sites
Labeling Zhangzhou as the world’s largest Hualong One base is accurate, but it sits within a broader landscape of mega scale nuclear stations that define the upper end of the industry. In Russia, for example, the Leningrad plant recently became the largest nuclear station in that country after its latest unit went commercial, yet by gross installed capacity the world’s largest operational nuclear station is in Canada. That title belongs to Canada’s Bruce site, which has eight units and a combined capacity that still sets the benchmark, as noted in analyses of how Canada Bruce compares with other large stations.
Japan is also reentering the conversation about very large nuclear plants as it prepares to restart the Kashiwazaki Kariwa complex, long described as the world’s biggest nuclear plant by capacity, 15 years after the Fukushima accident. Reports from Dec describe how Japan’s nuclear odyssey is coming full circle with the planned restart, while parallel coverage notes that Japan prepares to restart the world’s biggest nuclear plant with Tokyo Electric Power Company (TEPC) at the center of the effort. Against that backdrop, Zhangzhou’s claim is more specific, it is the largest base for a single advanced Chinese design, rather than the largest nuclear station by total capacity.
Climate, reliability and the politics of “clean” power
Bringing Zhangzhou Unit 2 into commercial service strengthens China’s argument that nuclear power is a necessary pillar of any serious decarbonization plan. Official descriptions of the site stress that Units 1 and 2 together can generate large quantities of clean electricity annually, displacing fossil fuel generation that would otherwise emit significant amounts of carbon dioxide. That framing aligns with broader narratives that present nuclear as a complement to wind and solar, providing steady baseload power that can backstop variable renewables, a role that is particularly important in fast growing coastal provinces like Fujian where industrial demand is high, as highlighted in accounts of the clean electricity annually that Zhangzhou provides.
At the same time, the politics of nuclear power remain complex, shaped by memories of accidents like Fukushima and by debates over waste management and cost. Japan’s cautious approach to restarting Kashiwazaki Kariwa, with Tokyo Electric Power Company and TEPC under intense scrutiny, shows how public trust can constrain even technically advanced projects, as detailed in Dec coverage of Tokyo Electric Power Company and its plans. China’s leadership, by contrast, has signaled a willingness to move quickly on nuclear construction, as seen in the approvals summarized under China Inks Approval for Four New Reactors, betting that a strong safety record at sites like Zhangzhou will keep domestic opposition in check.
What comes next for Zhangzhou and China’s nuclear push
With Phase I complete, attention at Zhangzhou now shifts to the remaining four Hualong One units planned for the site, which will determine whether the complex can fully realize its ambition as a six reactor powerhouse. The experience gained from bringing Units 1 and 2 online, from fuel loading to grid integration and the 168 hour full power assessment, should shorten commissioning timelines for subsequent units and reduce technical risk. Industry digests that spotlight China National Nuclear Corp and its work at Zhangzhou suggest that the company views the site as a template for future multi unit Hualong One bases.
More broadly, the successful start of commercial operation at Zhangzhou Unit 2 reinforces the trajectory outlined in national performance reports, which show dozens of reactors under construction and a steady pipeline of new approvals. As those projects come online, they will reshape the country’s power mix, reducing the share of coal while increasing the role of nuclear and renewables, a shift that is already visible in summaries of first reactors brought online at major bases. For now, Zhangzhou stands as the clearest example of how that strategy looks on the ground, a coastal complex where a domestically designed reactor has moved from blueprint to commercial workhorse in just a few years.
Supporting sources: Second unit of world’s largest nuclear power base brought ….
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