The upper part of the inner containment dome has been installed at unit 7 of China’s Tianwan NPP, which is being built with the assistance of Rosatom’s Engineering Division. The component weighs 214 tonnes and is 36 metres in diameter using a crane with a 2000 tonne lifting capacity.

Installation of the inner containment dome has been carried out in two stages. In May, the lower part of the dome (44 metres in diameter and weighing 391 tonnes) was installed on the containment’s cylindrical part in the reactor building.

“The construction of Tianwan 7 is proceeding on schedule,” said Alexey Bannik, Atomstroyexport Vice President for Projects in China and Prospective Projects. “The next step will be to install key equipment inside the reactor building, namely the reactor pressure vessel, steam generators, hydraulic tanks of the emergency core cooling system, pressuriser, and main circulation pumps.

The inner containment is constructed from pre-stressed reinforced concrete and consists of a cylindrical part and a hemispherical dome. The containment’s inner surface is lined with metal, to ensure tightness in all modes of NPP operation, including emergency events.

Tianwan NPP is the largest project of economic cooperation between Russia and China. 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.

The agreement for construction of Tianwan units 7&8 was signed by Russia and China in 1918 and commissioning is scheduled for 2026-2027. 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%).

The contract for units 7&8 signed by the Rosatom Engineering Division and CNNC companies. Subsequently executive contracts were also signed including a technical design contract and a general contract under which Rosatom’s Engineering Division is in charge of design and delivery of the nuclear island equipment and documentation and provision of associated services.

The Rosatom’s Engineering Division unites the leading companies of the nuclear industry, namely: Atomstroyexport JSC (Moscow, Nizhny Novgorod, branches in Russia and abroad), Joint Design Institute – Atomenergoproekt JSC (Moscow, Nizhny Novgorod, St Petersburg branches – design institutes, branches in Russia and abroad and R&D branches) and subsidiary construction organisations.

Earlier in June, the Petrozavodskmash plant of AEM-Technologies (part of Rosatom’s mechanical engineering division Atomenergomash) began shipping the main circulation pump (MCP) housings for Tianwan 7. The MCP circulates the coolant in the primary circuit and operates at a pressure of about 16 MPa and at a temperature of about 300 °C. When assembled with a spacer, the weight of an MCP housing is 48 tonnes. The shipment includes four housings with spacers.

Image: The upper part of the inner containment dome is lifted into position at Tianwan 7 (courtesy of Rosatom)