Cold functional tests verify the proper installation and functionality of safety-critical components under low-temperature conditions. These tests focus on ensuring the integrity of the primary circuit, including pressure vessels, pipelines, and valves across both nuclear and conventional systems, while also cleaning main circulation pipes. The final test maintained a primary loop pressure of 22.3 MPa for 10 minutes, confirming, as the company stated: “The primary circuit pressure boundary of the Hualong One unit was intact and well sealed.”
The next phase involves hot functional tests, which will raise the reactor coolant system’s temperature to simulate operational conditions. These tests, conducted before loading nuclear fuel, ensure that coolant circuits and safety systems meet design standards, validating the performance of both nuclear and conventional equipment.
Construction of unit 3’s nuclear island began with the pouring of the base slab in March 2021, followed by unit 4 in December of the same year. Changjiang Phase II, encompassing units 3 and 4, represents a joint investment of CNY 40 billion ($6.4 billion), with China Huaneng holding a 51% stake and China National Nuclear Corporation owning 49%. The project, spanning 60 months, aims for both units to commence full operations in early 2027.
A representative from Huaneng Hainan Changjiang Nuclear Power noted: “The successful completion of cold testing at unit 3 is a significant step toward ensuring the reliability and safety of our Hualong One technology as we progress toward operational readiness.”
The Changjiang site already hosts two CNP-600 pressurized water reactors, units 1 and 2, operational since 2015 and 2016, respectively. Additionally, in 2021, construction began on a 125 MWe ACP100 small modular reactor, known as Linglong One, designed for versatile applications such as electricity, heating, steam production, or seawater desalination.
This progress at Changjiang underscores ongoing efforts to expand clean energy infrastructure in Hainan province. The completion of cold testing for unit 3 demonstrates technical precision and sets the stage for further milestones. As the project advances, units 3 and 4 are expected to contribute significantly to the region’s energy needs, supporting sustainable development through reliable nuclear power. The site’s diverse reactor portfolio highlights its role in fostering innovation and energy reliability for the future.
