Concreting of containment building completed at Zhangzhou 1

The operation to pour the concrete over the outer containment shell took almost 17-and-a-half hours and was completed on 19 January, CNNC said.

The company noted that the outer containment of Zhangzhou 1 is composed of three parts: a cylinder, a quasi-spherical dome and an external water tank. "It is structurally connected with the fuel plant and electrical plant," CNNC said. "It is an important safety guarantee for nuclear power units - resistant to large aircraft collisions and magnitude 9 earthquakes."

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.

CNNC has adopted the "open roof" method of construction for both Zhangzhou 1 and 2, where a large crawler crane is used to lower the main equipment into the reactor building before the containment dome has been installed, rather than the traditional way of completing civil construction prior to installing the major components.