At unit 8 of China’s Tianwan NPP Rosatom has the lower part of the dome of the internal containment (VZO – Vnutrennei Zatsitnoi Obolochki). The large metal structures were assembled on the ground at a separate stand. The total weight of the structure was 375.5 tonnes. The hermetic shell of the reactor building will now be installed and concreted, and installation of the main equipment – reactor vessel, steam generators, the main circulation pipeline will begin, according to Alexey Bannik Vice President for projects in China at Atomstroyexport (general contractor and part of Rosatom).

Specialists will now assemble and install the upper part of the dome and weld the lower and upper tiers together. After the installation of the domed part is completed, the builders will continue to concrete the inner containment, which plays a pivotal role in preventing any radioactive material from leaking into the surrounding environment. The use of a double containment ensures the maximum protection. Outer containment (NZO – Naruzhnoi Zatsitnoi Obolochki) is a reinforced concrete structure that protects the reactor unit from external influences and is able to withstand an earthquake, tsunami or hurricane.

The agreement for construction of Tianwan 7&8 was signed by Russia and China in 1918 and commissioning is scheduled for 2026-2027. Construction of units 7&8, equipped with VVER-1200 reactors began in May 2021. Units 1-4, with VVER-1000 reactors commissioned between 2007 to 2018 are already in operation. Units 5&6 with Chinese ACPR-1000s were commissioned in 2020 and 2021.

Tianwan NPP is owned and operated by the Jiangsu Nuclear Power Corporation, whose shareholders are China National Nuclear Corporation (CNNC – 50% stake), China Power Investment Corporation (30%) and Jiangsu Guoxin Group (20%).

Image: Installation of the lower tier of the inner containment dome at Tianwan 8 (courtesy of Rosatom)