The outer dome of the containment building at unit 1 of China’s Zhangzhou NPP in Fujian province has been completed. China National Nuclear Corporation (CNNC) said the operation to pour the concrete over the outer containment shell took almost 17.5 hours.

Zhangzhou 1 is the first of two Hualong One units being built at the plant. They are scheduled to begin commercial operation in 2024 and 2025

CNNC explained that 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. It is an important safety guarantee for nuclear power units – resistant to large aircraft collisions and magnitude 9 earthquakes."

The steel dome for Zhangzhou unit 1's inner containment was installed in October 2021 and concreted in May 2022. The main function of the double-layered containment building is to ensure the integrity and leak tightness of the reactor building. It plays a key role in the containment of radioactive substances. The inner safety dome was installed on the containment building of Zhangzhou 2 in August 2022.

The open top method is being used for construction of both Zhangzhou units. This involves a large crawler crane lowering the main equipment into the reactor building before the containment dome has been installed. This saves time compared with the traditional method of completing civil construction before installing the major components.

Construction licences for Zhangzhou 1&2 were issued by the Ministry of Ecology & Environment in 2019 to CNNC-Guodian Zhangzhou Energy Company, the owner of the Zhangzhou nuclear power project owned by CNNC (51%) and China Guodian Corporation (49%). The licences are valid for 10 years.

Image: The completed outer dome at unit 1 of China’s Zhangzhou nuclear power plant (courtesy of CNNC)