Unit 5 at the Fuqing nuclear power plant in China's Fujian province attained a sustained chain reaction for the first time yesterday, China National Nuclear Corporation (CNNC) has announced. The unit - the first of two demonstration Hualong One reactors at the site - is scheduled to begin commercial operation by the end of this year, with unit 6 following by the end of next year. Unit 5 will be the world's first Hualong One reactor to be commissioned.

China's Ministry of Ecology and Environment issued the operating licence for Fuqing 5 on 4 September. The process of loading the 177 fuel assemblies into the reactor core began the same day and was completed on 10 September. Yesterday, at 3.09pm, the reactor achieved first criticality after the boron concentration in the primary loop was diluted and the control rods were withdrawn.

Various commissioning tests will now be carried out at the Hualong One, prior to it being connected to the electricity grid. It will then undergo tests at increasing power output levels before entering a full-power demonstration operating assessment. During this assessment stage, the performance indicators of the unit will need to meet design standards and the relevant requirements of the power grid, which will indicate that the unit has achieved formal commercial operating conditions.

China's State Council gave final approval for construction of Fuqing units 5 and 6 in April 2015. The pouring of first concrete for Fuqing 5 began in May that year, marking the official start of construction of the unit. Construction of unit 6 began in December the same year. The inner dome of unit 5 was installed on the containment building in May 2017, with the outer dome installed in January 2018.

Hot testing at Fuqing 5 was completed on 2 March. These tests involved increasing the temperature of the reactor coolant system and carrying out comprehensive tests to ensure that coolant circuits and safety systems are operating as they should. Such testing simulates the thermal working conditions of the power plant and verifies that nuclear island and conventional equipment and systems meet design requirements.

Construction of two demonstration Hualong One (HPR1000) units is also under way at China General Nuclear's Fangchenggang plant in the Guangxi Autonomous Region. Those units are expected to start up in 2022. 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.

Two HPR1000 units are under construction at Pakistan's Karachi nuclear power plant. Construction began on Karachi unit 2 in 2015 and unit 3 in 2016; the units are planned to enter commercial operation in 2021 and 2022.