Cold hydrostatic tests have been completed at unit 7 of China’s Tianwan NPP in Jiangsu province, according to China National Nuclear Corporation (CNNC). The main purpose of the tests is to check the tightness of the primary circuit and its elements (reactor casings, pipelines and fittings of both nuclear and conventional islands), as well to clean the main circulation pipes.
CNNC said the completion of cold tests means that the unit transitions from the installation stage to the commissioning stage “and creates a solid basis for the safe conduct of complex commissioning work on subsequent units”.
The next stage will be hot tests, during which the temperature of the reactor system coolant will be increased, and comprehensive checks of the performance of cooling circuits and safety systems will be carried out. These tests, carried out before loading nuclear fuel, simulate the thermal operating conditions of the plant and confirm the compliance of the equipment of the nuclear and conventional islands with the design requirements.
In 2018, Russia and China signed four agreements, including for the construction of two VVER-1200 reactors for Tianwan units 7&8. Construction of unit 7 began in May 2021, and unit 8 in February 2022. The units are scheduled to be commissioned in 2026-2027. Tianwan 1-4, with VVER-1000 reactors, commissioned between 2007 and 2018, are already in operation. Units 5&6 with Chinese ACPR-1000s were commissioned in 2020 and 2021.
Tianwan NPP is owned and operated by the Jiangsu Nuclear Power Corporation, whose shareholders are CNNC (50%), China Power Investment Corporation (30%) and Jiangsu Guoxin Group (20%).
