Changjiang 3 containment building completed

Tuesday, 1 July 2025

"This marks the completion of the main structure of the reactor building of the nuclear island of unit 3 and the entry of the project construction into a new stage, laying a solid foundation for the full launch of subsequent nuclear island hot test and commissioning," China National Nuclear Corporation said.

First concrete was poured for the base slab of unit 3's nuclear island in March 2021, with that of unit 4 being poured in the December of that year. Changjiang Phase II - units 3 and 4 - represents a total estimated investment of CNY40 billion (USD6.4 billion), according to China Huaneng, which holds a 51% share in the project, with China National Nuclear Corporation holding the remaining 49%. The construction period is expected to be 60 months. Both Hualong One (HPR1000) units are scheduled to be fully operational in early 2027.

The Hualong One reactor design features a double-layered containment building, the main function of which is to ensure the integrity and leak tightness of the reactor building, and it plays a key role in the containment of radioactive substances.

The steel dome for Changjiang unit 3's inner containment - measuring more than 46 metres in diameter and 23 metres in height - was placed on top of the walls of the double containment structure in February 2023.

The outer steel dome - measuring 53 metres in diameter, 13 metres in height and weighing about 415 tonnes - was hoisted into place on top of the containment building in October last year.

Cold hydrostatic testing - carried out to confirm whether components and systems important to safety are properly installed and ready to operate in a cold condition - were completed in April. These will now be followed by hot functional tests, which involve increasing the temperature of the reactor coolant system and carrying out comprehensive tests to ensure that coolant circuits and safety systems are operating as they should.

The Changjiang nuclear site is already home to two operating CNP-600 pressurised water reactors (PWRs) - Changjiang 1 and 2 - which entered commercial operation in 2015 and 2016, respectively. In 2021, CNNC also began construction of a demonstration ACP100 small modular reactor at the site. The multi-purpose 125 MWe PWR - also referred to as the Linglong One - is designed for electricity production, heating, steam production or seawater desalination.