The fourth and final steel ring of the main containment shell has been installed at unit 3 of China’s Sanmen NPP in Zhejiang province, according to China National Nuclear Corporation subsidiary Sanmen Nuclear Power Company.
The steel containment consists of six modules – the bottom head, four ring cylinder modules and the top head. Installation of the 749-tonne fourth ring of the containment shell, with an inner diameter of about 40 metres and a height of about 8 metres, lasted two hours. Sanmen Power Company said the installation of the fourth ring “lays a solid foundation for the milestone of the top head of the containment shell of unit 3”.
The construction of two new units at each of the Sanmen (3&4), Haiyang (3&4) and Lufeng (5&6) NPPs was approved by China’s State Council in April 2021. Two Westinghouse AP1000 units built as Phase I of the Sanmen plant (1&2) started operation in 2018. Two CAP1000 reactors are being constructed as Phase II of the plant (units 3&4). First concrete was poured for the nuclear island of Sanmen 3 in June 2022 and for unit 4 in March 2023.
The CAP1000 is China’s version of the Westinghouse AP1000. It uses modular construction techniques, enabling large structural modules to be built at factories and then installed at the site. This reduces construction time and improves quality control. First concrete was poured for the nuclear island of Sanmen 3 in June 2022 and first concrete for unit 4 in March 2023. The units are expected to be connected to the grid in 2027 and 2028.be connected to the grid in 2027 and 2028.
