Cold functional tests verify the proper installation and functionality of safety-critical components under cold conditions. These tests ensure the leak-tightness of the primary circuit, including pressure vessels, pipelines, and valves in both nuclear and conventional islands, while also cleaning main circulation pipes. CNNC stated: “Completion of cold testing marks the full transition of unit 7 of the Tianwan nuclear power plant from the installation stage to the commissioning stage, and also laid a solid foundation for the safe and orderly implementation of the comprehensive commissioning work of subsequent units.”
The next phase involves hot functional tests, where the reactor coolant system’s temperature is raised to simulate thermal operating conditions. These tests, conducted before nuclear fuel loading, confirm that coolant circuits and safety systems meet design standards, ensuring the reliability of nuclear and conventional equipment.
The Tianwan nuclear power plant, located in Jiangsu province, is operated by Jiangsu Nuclear Power Company, a joint venture between CNNC (50%), China Power Investment Corporation (30%), and Jiangsu Guoxin Group (20%). Units 7 and 8, featuring Russian-designed VVER-1200 reactors, were agreed upon in June 2018 through contracts between Russia and China. Construction of Unit 7 began in May 2021, followed by Unit 8 in February 2022. Commercial operation is scheduled for 2026 for Unit 7 and 2027 for Unit 8.
The Tianwan facility includes eight units in total. Units 1 through 4, operational since June 2007 to December 2018, utilize Russian-supplied Gidropress VVER reactors, as will Units 7 and 8. Units 5 and 6, however, are equipped with Chinese-designed ACPR1000 reactors, reflecting a blend of international and domestic technology.
This milestone supports the plant’s ongoing efforts to enhance energy production capacity for domestic consumption, ensuring a stable and safe electricity supply. The completion of cold testing for Unit 7 sets the stage for further commissioning activities, advancing the project toward its operational goals.
