China National Nuclear Corporation announced the installation of the final module of the passive water tank in the reactor building of unit 4 at the Xudabao nuclear power plant, located in Liaoning Province. This milestone marks the full completion of the modular construction of major components for the project’s second phase, comprising two Russian-supplied VVER-1200 reactors.
Large-scale modular design
The passive tank, a key element of the heat removal system in the event of a primary circuit leak, is composed of four modules. Each weighs 325.9 tonnes and includes reinforced concrete slabs, stainless steel cladding, heat exchangers, and wall penetrations. The final assembled tank features 33 penetrations and 16 heat exchangers.
The modular system allows condensation of steam from the primary circuit inside steam generators, with the condensate returning to the reactor core to provide additional cooling. This technology is designed to enhance the inherent safety of new-generation reactors.
Four years of work and innovative method
The modular construction process extended over four years. Since the initial lifting of unit 3’s core shaft module in November 2021, project teams have implemented a strategy of systematic modular integration. This approach enabled improved schedule control and precision levels exceeding design requirements.
Technical innovations included a “four-in-one” combined hoisting operation, integrating the containment steel liner, through-hole components, steel truss, and horizontal steel mesh. This method was developed and implemented for the first time at such scale in a Chinese nuclear project.
Progressive deployment of VVER and CAP1000 reactors
The Xudabao site, also known as Xudapu, was originally intended to host six CAP1000 reactors, a Chinese adaptation of the American AP1000 model. Units 1 and 2 were to be prioritised. However, units 3 and 4 were reassigned to the VVER-1200 design under a cooperation agreement with Russia, with commissioning scheduled for 2027 and 2028.
In November 2023, Chinese environmental authorities granted construction permits for units 1 and 2, which will be equipped with CAP1000 reactors. Two additional CAP1000 reactors are planned for Phase III of the project.
A project led by a Chinese consortium
The Xudabao nuclear plant is owned 70% by China National Nuclear Corporation, 20% by Datang International Power Generation Company, and 10% by State Development and Investment Corporation. The site remains a central part of China’s nuclear expansion strategy, supporting industrialised nuclear construction methods.
