Cold tests completed at second Karachi Hualong One

Cold functional tests are carried out to confirm whether components and systems important to safety are properly installed and ready to operate in a cold condition. The main purpose of these tests is to verify the leak-tightness of the primary circuit and components - such as pressure vessels, pipelines and valves of both the nuclear and conventional islands - and to clean the main circulation pipes. The tests mark the first time the reactor systems are operated together with the auxiliary systems.

Completion of the cold testing of Karachi 3 was overseen by the Pakistan Nuclear Regulatory Authority and the Pakistan Atomic Energy Commission (PAEC), CNNC said.

The successful completion of the cold testing means that the main work of the nuclear island installation project of the unit has been completed and the unit has entered the system commissioning stage, CNNC said. Cold testing will be followed by thermal testing, then first fuel loading and finally grid-connected power generation.

Karachi 2 and 3 are being constructed under a contract worth about USD9 billion signed between China National Nuclear Corporation and the PAEC in 2013. Construction of unit 2 began in 2015 and unit 3 in 2016. Installation of the reactor internals of Karachi 2 was completed in January 2019, while installation of unit 3's was completed in April last year.

Karachi 2 achieved first criticality - attaining an initial sustained chain reaction - on 28 February this year. Following a series of commissioning tests, the unit was connected to the grid on 18 March. It is scheduled to enter commercial operation later this year, with unit 3 following next year.

In addition to the two units under construction at Karachi, four demonstration Hualong One units are being built in China - two units CNNC's site at Fuqing in Fujian province, and two at China General Nuclear's Fangchenggang site in Guangxi province. All four units are expected to be connected to the Chinese grid by the end of 2022. Fuqing 5 was connected to the grid on 27 November, having achieved first criticality on 21 October, and entered commercial operation on 30 January. CNNC has also started construction of two Hualong units at the Zhangzhou plant in Fujian province, plus the first of two units at Taipingling in Guangdong.