Construction of China's Xudabao 4 nuclear unit passes important milestone

Construction of China's Xudabao 4 nuclear unit has moved into its next phase after workers successfully installed the reactor containment dome, weighing more than 650 tonnes. Along with its sister unit Xudabao 3 (both VVER-1200 units), the unit is now awaiting the installation of technology and equipment. Current plans envisage Xudabao 3 and 4, in Liaoning province, entering commercial operation in 2027 and 2028. 

China National Nuclear Corporation (CNNC) announced that construction of its nuclear unit reached an important milestone on June 18. Technicians installed the dome of the VVER-1200 Xudabao 4 unit.

"The dome is an important component in ensuring the integrity and airtightness of the reactor building. The structure has a diameter of 44 metres and is positioned between 44.6 and 66.6 metres above ground. The dome contains an internal steel structure, equipment supports and hangers, sprinkler systems, lighting systems, hydrogen elimination equipment, equipment for heat exchangers, detection equipment and other equipment. Its total weight is 655.37 tonnes," CNNC said in a press release.

For the dome installation, CNNC used for the second time a system in which, instead of being lifted in two sections, the dome is assembled on the ground and hoisted as a single unit. This saves workers installation time overall; at Xudabao 4, placing the dome took 3.5 hours.

An interesting feature of the Xudabao power plant is that CNNC began work first on units 3 and 4. The first two units are to use CAP1000 technology, with construction of the first starting in November last year. Construction of Xudabao 2 has yet to begin.

Russian nuclear units in China

China began construction of two Russian units at the Xudabao plant and two units at the Tianwan plant in 2021 and 2022. The basis for Chinese-Russian cooperation is the 2019 agreement on the supply of the new units. Russia is responsible for supplying the nuclear island and nuclear fuel. China will supply the turbines and generators for the new units.

All the units are due to begin generating electricity by 2028. The two units at Xudabao will generate around 18 TWh of electricity a year, saving almost 19 million tonnes of CO2 emissions.

China currently operates four Russian-designed VVER-1000 units, all at the Tianwan plant (units 1 to 4).