China’s first commercial land based small modular reactor moved closer to grid operation in December after the ACP100 demonstration project at Changjiang in Hainan completed its non nuclear turbine steam run on the first attempt, according to China National Nuclear Corporation.
For a reactor class often promoted for construction speed and operational simplicity, the test offers an early indicator of whether those claims can hold under real project conditions.
The non nuclear turbine run, completed on December 23, verified stable operation across all conventional island systems, with the steam turbine generator meeting its design parameters. In nuclear project sequencing, this milestone functions as a full scale operational rehearsal of the balance of plant before fuel loading. It tests thermal performance, control systems, and mechanical integration without nuclear heat, reducing uncertainty ahead of hot functional testing and first criticality.
For CNNC, the result matters beyond a single unit. The ACP100, also branded as Linglong One, is positioned as the reference design for China’s domestic SMR rollout and a potential export platform. Demonstrating predictable commissioning behavior is therefore as strategically important as meeting power output targets.
Construction progress to date broadly aligns with CNNC’s original schedule. First concrete was poured in July 2021, with a planned construction period of 58 months. Equipment installation began in December 2022, the main internal reactor building structure was completed in March 2023, and the outer containment dome was installed in February 2024. Cold functional testing was completed on October 16, marking the first integrated operation of reactor and auxiliary systems and confirming leak tightness of the primary circuit.
The Changjiang site itself provides a controlled environment for first of a kind deployment. It already hosts two operating CNP600 pressurized water reactors, with two Hualong One units under construction and expected to enter commercial operation by the end of 2026. This clustering reduces grid connection risk and benefits from an experienced local workforce, factors that are often understated in SMR cost and schedule projections.
At 125 megawatts electric, the ACP100 sits at the upper end of the SMR category. CNNC estimates annual output at roughly one billion kilowatt hours, enough to supply about 526,000 households based on Chinese consumption metrics. The integrated pressurized water reactor design is intended to support multiple applications including electricity generation, district heating, industrial steam, and seawater desalination. That versatility is frequently cited as a differentiator, although actual deployment beyond power generation will depend on site specific economics and regulatory approvals.
From a regulatory perspective, the design’s early validation remains one of its stronger credentials. Development began in 2010, preliminary design was completed in 2014, and in 2016 the ACP100 became the first SMR to pass a safety review by the International Atomic Energy Agency. While an IAEA review does not substitute for national licensing, it does lower barriers for dialogue with foreign regulators, particularly in emerging nuclear markets.
China plans to begin commercial operation of the Changjiang ACP100 in the first half of 2026, according to comments reported by Reuters from a CNNC research institute official in December. That timeline places the project roughly five years from first concrete to operation, faster than large scale reactors but still longer than some SMR advocates initially projected. The gap highlights a persistent tension in the SMR narrative between modular ambition and the realities of nuclear construction, even within a centralized system like China’s.
The successful turbine test also arrives as China accelerates nuclear capacity additions more broadly. Large reactors remain the backbone of expansion, but SMRs are increasingly framed as complementary assets for coastal regions, industrial parks, and remote grids. Whether ACP100 can transition from a single demonstration unit to serial production will depend on cost transparency, repeatability of construction schedules, and evidence that smaller units can achieve competitive levelized costs when deployed at scale.
