The nuclear circuit flushing of the China-built K2 reactor in the Karachi nuclear power plant in Pakistan began on June 22, according to local news reports.

The K2 is the first overseas unit using Hualong One – or HPR 1000 -- nuclear technology, a domestically developed third-generation nuclear reactor design.

It was built by China Zhong Yuan Engineering Corporation, or CZEC, a unit of China National Nuclear Corporation, also known as CNNC.

Experts said that the start of nuclear circuit flushing means that the main structure installation of the main nuclear auxiliary system of the nuclear island has basically finished, and it is also one of the important prerequisites for the ensuing cold functional test.

Cold functional tests are carried out to confirm whether the main system and its supporting facilities are properly installed and ready to operate under high-pressure conditions.

The successful start of the nuclear circuit flushing lays a solid foundation for subsequent important nodes in the K2 reactor, according to officials.

Workers start the nuclear circuit flushing of the China-built K2 reactor in the Karachi nuclear power plant in Pakistan, on June 22. [Photo/CNNC]