The top head of the steel containment vessel (inner dome) has been installed at unit 1 of China’s Xudabao NPP in Liaoning Province. China National Nuclear Corporation (CNNC) said this “marked the transition of the unit’s construction from civil engineering to the installation phase”.
The Xudabao project was originally expected to comprise six CAP1000 reactors with units 1&2 as the first phase. However, plans changed, and two Russian-supplied VVER-1200 reactors were instead designated for Xudabao 3&4 with construction starting in July 2021 and May 2022 for commissioning in 2027 and 2028. In November 2023, the Ministry of Ecology & Environment announced that the National Nuclear Safety Administration had decided to issue a construction licence for Xudabao 1&2 with 1250 MWe CAP1000 reactors – the Chinese version of the Westinghouse AP1000. Two further CAP1000 reactors are proposed for units 5&6.
The steel containment vessel of the CAP1000 comprises six modules: a bottom head, a cylindrical shell (four rings), and a top head. The top head is assembled and welded together from 64 curved steel plates. This forms a semi-elliptical structure, weighing over 820 tonnes, with an inner diameter of some 40 metres and a height of more than 11 metres. Before it was lifted into place multiple systems and equipment were installed, including fire sprinklers, temporary ventilation, and airflow turbulence. This reduced subsequent construction work within the nuclear island, improving construction efficiency and reducing installation risks.
CNNC said installation of the top cover has paved the way for subsequent installation, commissioning and grid-connected power generation, laying “a solid foundation for Liaoning Province to build an integrated wind, solar, thermal, nuclear and storage energy base”. Once the Xudabao project is fully completed, it will provide nearly 540,100 GWh of clean energy, reducing carbon dioxide emissions by 5,670 tonnes a year.
The Xudabao plant is owned by Liaoning Nuclear Power Company Ltd, in which CNNC holds a 70% stake with Datang International Power Generation Company holding 20% and State Development and Investment Corporation owning 10%. The general contractor is China Nuclear Power Engineering Company Ltd, a subsidiary of CNNC.
