The outer steel dome has been installed at unit 1 of the Zhangzhou nuclear power plant in China's Fujian province, China Nuclear Engineering and Construction Corporation (CNECC) announced. Zhangzhou 1 is the first of two Hualong One units being built at the site, scheduled to enter commercial operation in 2024 and 2025, respectively.

The outer steel dome is installed at Zhangzhou 1 (Image: CNECC)

The dome - measuring 55 metres in diameter, 13 metres in height and weighing about 420 tonnes - was hoisted into place on top of the containment building using a 3200-tonne crane on 17 February.

CNECC - a subsidiary of China National Nuclear Corporation (CNNC) - said its installation marks "the completion of the unit's main structure construction, and for subsequent installation cold tests and grid connection". It added, "A solid foundation has been laid for power generation, and a solid step has been taken in the batch construction of Hualong One".

The main function of the double-layered containment building 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 Zhangzhou unit 1's inner containment - measuring 45 metres in diameter and almost 14 metres in height, and weighing about 260 tonnes - was raised by crane and placed on top of the walls of the double containment structure in October 2021. The concreting of the inner containment dome was completed in May last year.

China's Ministry of Ecology and Environment issued construction licences for Zhangzhou units 1 and 2 on 9 October 2019 to CNNC-Guodian Zhangzhou Energy Company, the owner of the Zhangzhou nuclear power project which was created by CNNC (51%) and China Guodian Corporation (49%) in 2011. The licences are valid for 10 years. Construction of unit 1 began one week after the issuance of the construction licence, with that of unit 2 starting in September 2020. The units are scheduled to enter commercial operation in 2024 and 2025, respectively.

The inner safety dome was installed on the containment building of Zhangzhou unit 2 in August 2022.