Milestone Reached in Construction of Tianwan NPP's Unit 7

A momentous achievement has been reached in the construction of Unit 7 at the Tianwan Nuclear Power Station (NPS) in China. The lower tier of the liner within the inner containment
Tianwan Nuclear Power
Tianwan Nuclear PowerImage Source – ROSATOM

A momentous achievement has been reached in the construction of Unit 7 at the Tianwan Nuclear Power Station (NPS) in China. The lower tier of the liner within the inner containment dome of the reactor building has been successfully lifted into place. This remarkable milestone showcases the successful collaboration between Russia and China in constructing advanced power units and symbolizes their unwavering commitment to technological sovereignty.

The large-sized metal structure, weighing 391 tons with a diameter of 44 meters, has been meticulously installed in its designated position on the cylindrical part of the reactor building containment. To accomplish this task, a crane with an impressive maximum lifting capacity of 2,000 tons was transported to the construction site, ensuring the precise placement of the liner.

This notable event coincides with the two-year anniversary of the momentous occasion when the heads of Russia and China, Vladimir Putin and Xi Jinping, participated via a video conference in the ceremony marking the first concrete pouring into the foundation slab of Unit 7's reactor compartment. This event symbolized the commencement of the construction of the fourth stage of the Tianwan NPS. The project stands as a shining example of the successful cooperation between the two nations. Over several decades, experts from Russia and China have worked together to construct the most advanced power units of the NPS, continually improving and optimizing production processes while steadfastly advancing towards technological sovereignty.

The next phase of the project will involve completing the installation of the top tier of the liner and the necessary equipment and pipelines, weighing a total of 214 tons. This crucial step will pave the way for key installation works inside the reactor building, encompassing the installation of the reactor pressure vessel, steam generators, emergency core cooling system tanks, pressurizer, reactor coolant pumps, and other essential equipment, as well as the welding of the main coolant pipeline.

The reactor building serves as the primary structure at the NPS, housing the nuclear steam supply system and its emergency cooldown systems. The incorporation of double containment design ensures maximum protection against accidental releases of radioactive products into the environment. The reinforced concrete structure safeguards the reactor plant from external impacts, capable of withstanding earthquakes, tsunamis, or hurricanes. An outer containment provides physical protection for the inner containment, which consists of a pre-stressed reinforced concrete cylindrical part and a hemispherical dome. The inner containment's internal surface is lined with metal, ensuring leak-tightness in all operating modes, including emergency scenarios. This dual containment system is a distinctive feature of the Russian design of power units with VVER-1200 reactors, guaranteeing the highest level of safety.

Tianwan NPS represents the largest economic cooperation project between Russia and China. Presently, two power units are being constructed based on the Russian VVER-1200 design, while the previous four units, using the VVER-1000 design, operate successfully, supplying millions of kilowatts of energy to the national power grid. The signing of the Intergovernmental Protocol and the frame contract for the construction of Units 7 and 8 with VVER-1200 reactors in 2018 solidified the collaboration. As per the agreements, the Russian side has undertaken the design of the NPS nuclear island and will supply the key nuclear island equipment for both units. The Engineering Division of the Rosatom State Corporation is involved in the design and delivery of the nuclear island documentation and equipment, along with providing associated services. The construction of Units 7 and 8 began on May 19, 2021, marking a significant step forward in the ambitious project.

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