First criticality means the plant achieved a controlled, self-sustaining nuclear fission chain reaction for the first time.
The criticality operation began on 20 April with permission to proceed from the regulator and was completed on 21 April at 01:13 local time after about 18 hours, CNEA said.
In late March, fuel loading was completed at Hongyanhe-6, a Generation III ACPR-1000 pressurised water reactor, construction of which began in July 2015.
The ACPR-1000 reactor – ACPR stands for Advanced Chinese PWR (pressurised water reactor) –was designed by the China Guangdong Nuclear Power Corp, which changed its name to CGN in 2013.
CNEA said the next stages of the commissioning phase will include grid connection and performance testing before the unit can be approved for commercial operation later this year.
There are five other units in commercial operation at the Hongyanhe site. Units 1 to 4 are of the CPR-1000 design while Unit 5, which began commercial operation last year, is another ACPR-1000.
According to the 14th Five-Year Plan (2021-25), China wants to have 70 GW of installed nuclear capacity by 2025, up from 51 GW at the end of 2020 and an increase of more than 40%, after failing to meet its previous target of having 58 GW of installed capacity by 2020.
The State Council recently approved the construction of six new commercial nuclear power plants.
According to data by the International Atomic Energy Agency, China has 53 nuclear reactor units in commercial operation. The Chinese fleet generated about 5% of the country’s electricity in 2021.