China’s Hualong One Reactor Achieves First Criticality, Bringing 2027 Power On Track

At 18:00 local time on 10 July, the Changjiang Unit 3 reactor in Hainan Province entered its first criticality, signalling a major step toward commercial power generation, according to China National Nuclear Corporation (CNNC).

First Criticality Signals Progress Toward Grid Connection

Reaching first criticality means the reactor can sustain a controlled fission chain reaction without external neutron sources. Although the plant will not yet produce electricity, CNNC indicated that a series of low‑power physics tests will follow, during which safety systems and performance parameters will be validated before the unit is synchronized with the grid.

The unit is a 1,100 MWe Hualong One (also called HPR1000), a Generation‑III pressurised‑water design co‑developed by CNNC and China General Nuclear (CGN). Its safety architecture combines active and passive features, a double‑layer containment envelope and a design lifespan of 60 years, delivering roughly 1.1 GW of electrical output.

Construction of Unit 3 began in March 2021 with the first concrete pour for the nuclear island, and Unit 4 started later that year. Information released by China Huaneng and reported by World Nuclear News places the Phase II investment at about CNY 40 billion (approximately US$5.9 billion). Both reactors are slated for full operation in early 2027.

Earlier milestones include the loading of nuclear fuel on 30 April, a step that CCTV News described as the commencement of nuclear commissioning and the transition into the core phase leading toward electricity generation.

Changjiang Site Merges Established Reactors with SMR Innovation

The Changjiang complex already operates two CNP‑600 pressurised‑water reactors (Units 1 and 2), which entered commercial service in 2015 and 2016 and continue to supply power to Hainan. In addition, the site hosts the Linglong One demonstration project, known as the ACP100, a 125 MWe small modular reactor designed for electricity, district heating, industrial steam and seawater desalination. World Nuclear News reports that the SMR is currently undergoing pre‑commissioning trials.

Provincial energy planners have earmarked nuclear power as the primary source for Hainan’s future electricity supply, aiming to meet rising demand while curbing reliance on fossil fuels.

While the first criticality marks a significant achievement for Unit 3, additional testing will continue before the reactor is linked to the grid and begins commercial service. Upon completion, Unit 3 will join the existing fleet at Changjiang, and Unit 4 will progress toward becoming the next Hualong One addition to China’s growing nuclear portfolio.