The largest and heaviest module has been installed at unit 4 of the Sanmen nuclear power plant, the Shanghai Nuclear Engineering Research and Design Institute (SNERDI) has announced. Two CAP1000 units - the Chinese version of the AP1000 - are being constructed as Phase II of the plant, in China's Zhejiang province.

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

The cuboid-shaped CA20 module comprises plant and equipment for used fuel storage, transmission, the heat exchanger and waste collection, among other things. The module measures 20.5 metres long, 14.1 metres wide and 20.9 metres high.

At 08:28 on 25 April, after a series of hoisting operations, the CA20 module of the unit was moved into place, SNERDI said. The total weight of the hoisting was 1024 tonnes, and it 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 CA20 module.

The CA20 module in place on the foundation of unit 4's nuclear island (Image: SNERDI)

The CAP1000 reactor design - the Chinese version of the AP1000 - 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 (which was installed in August 2022), the installation items of the CA20 module of unit 4 were optimised during the assembly stage," SNERDI noted. "Without affecting the 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."

It added: "The smooth installation of the CA20 module of unit 4 of Sanmen nuclear power plant officially opened the prelude to the installation of the No.4 nuclear island and started a new journey of comprehensive construction on the island."

The construction of two new reactors at each of the Sanmen, Haiyang and Lufeng sites in China was approved by China's State Council in April 2021. The approvals were for Sanmen units 3 and 4, Haiyang 3 and 4 and units 5 and 6 of the Lufeng plant. The Sanmen and Haiyang plants are already home to two Westinghouse AP1000 units each, and two CAP1000 units were approved for Phase II (units 3 and 4) of each plant.

The first safety-related concrete was poured for the nuclear island of Sanmen 3 on 28 June last year, marking the official start of its construction. The first concrete for that of unit 4 was poured in March this year.