China’s Shanghai Nuclear Engineering Research & Design Institute (SNERDI) says the largest and heaviest module has been installed at unit 4 of the Sanmen NPP in Zhejiang province. The CA20 module is 20.5 metres long, 14.1 metres wide and 20.9 metres high. It comprises plant and equipment for used fuel storage, transmission, the heat exchanger and waste collection, among other things. The total weight of the hoisting was 1024 tonnes, and installation was carried out using a 2600-tonne crawler crane. More than 1376 cubic metres of concrete will now be poured to fill the walls of the module.

China’s State Council approved construction of two new units at each of the Sanmen NPP (3&4), Haiyang NPP (3&4) and Lufeng NPP (5&6) in 2021. The approvals were for Sanmen units 3&4, Haiyang 3&4 and units 5&6 of the Lufeng plant. Sanmen 1&2 and Haiyang 1&2 (Phase I) are Westinghouse AP1000 units. CNNC signed contracts for the civil construction of the nuclear islands and installation engineering for phase II at Sanmen and Haiyang in April 2022. China Nuclear Industry 22 Construction Company was contracted for the Sanmen Phase II nuclear island, and China Nuclear Industry 24 Construction Company for the Haiyang Phase II nuclear island. China Nuclear Industry Fifth Construction Company (CNI5) will undertake the nuclear island installation work at all four units.

First concrete for Sanmen 3 was poured in June 2022 and for Sanmen 4 in March 2023.

The CAP1000 reactor is China’s version of the AP1000. It uses modular construction techniques, enabling large structural modules to be built at factories and then installed at the site. "Compared with the CA20 module of unit 3 (installed in August 2022), the installation components of the unit 4 CA20 module were optimised during the assembly stage," SNERDI said. "Without affecting installation of the main body, the installation of some bulk items such as OLP panels, penetrations, steel bars and pipes was completed ahead of schedule." This paves the way for installation of the unit 4 nuclear island.

Image: The CA20 module being hoisted into place (courtesy of SNERDI)