(Photo/CGTN)

A fourth nuclear power unit at Fuqing branch of China National Nuclear Corp (CNNC) began commercial operations on Sunday.

The China-designed No. 4 unit brings the total installed capacity to 4.35 million kw. The first unit was put into use in 2014.

The nuclear power units in Fuqing have generated 42 billion kwh of electricity.

The government has approved six additional nuclear power units to be built at the CNNC Fuqing branch. The No. 5 and 6 units will be a pilot project featuring Hualong One technology, a domestically-developed third-generation reactor design.

In May, a hemispherical dome was installed on the fifth unit, marking the completion of the construction work on the pilot project and the beginning of the assembly stage.

Currently, the CNNC has 17 operating nuclear power units. China has 36 operational nuclear reactors and is building 20 more, aiming to have 58 million kw of nuclear power capacity in operation by 2020.

China's legislature passed a Nuclear Safety Law on September 1 this year, which reflects the country's nuclear safety outlook, as well as its commitment to fulfilling obligations under international treaties.