On Feb 1, the vortex examination device and technology of the VVER-1000 unit horizontal-type vapor generator thermal transmission tube, independently researched and developed by China National Nuclear Corporation (CNNC), was successfully fitted to Unit 3 of Tianwan Nuclear Power Plant.

The incident shook off China’s dependence on imported devices from aboard in the nuclear sector, and proved that CNNC has thoroughly mastered the VVER unit core device in-service examination technology.

The device features precise and fast positioning, as well as high stability, which substantially increases the examination efficiency, shortens the follow-up units overhaul and debugging project duration, improves the ability of in-service examination, and expands the export of China’s nuclear power operations and maintenance technologies.

The vapor generator thermal transmission tube is known as the most vulnerable part of a nuclear power plant’s primary circuit pressure boundary, and the focal part of in-service monitoring during the operation period of nuclear power units.

At present, the advanced vortex examination device and technology of the horizontal-type vapor generator thermal transmission tube has been mastered by only several countries, Croatia included.

Tianwan Unit 1 and Unit 2 both utilized imported devices to conduct the vortex examination of the vapor generator thermal transmission tube. 

Due to the incapacity to core design parameters, the guarantee of reliability of examination devices was a key and difficult point during the vortex examination process, and restricted the optimization of examination technologies and project duration on overhaul.