FUZHOU - A containment dome has been installed on a reactor at China's nuclear power project using Hualong One technology, a domestically-developed third generation reactor design.

The dome, weighing 342 tonnes and measuring 46.8 meters in diameter, was installed using a crane on the No. 6 nuclear power unit in Fuqing, Southeast China's Fujian province at Wednesday, according to the China National Nuclear Corporation (CNNC).

The installation was finished ten days ahead of schedule, marking the completion of civil works and the beginning of the assembly stage, the CNNC said.

The dome ensures the nuclear reactor is well sealed, preventing radioactivity and other nuclear accidents.

"Considering its weight and volume, the installation was very demanding," said Liu Bin, an official with the nuclear project.

The dome was the second of its kind using Hualong One design installed on a reactor. The first, on the No. 5 unit, was completed last May.

Hualong One reactors were jointly designed by two nuclear power giants, China General Nuclear Power Group and CNNC, and passed inspection by a national panel in August 2014.

China has since approved the use of Hualong One technology to build two reactors in Fujian, the No. 5 and No. 6 units.

Hualong One reactors are among six units at the Fuqing nuclear project, of which four units have already been put into commercial operation.

It is estimated that the four operating units have generated more than 55 billion kwhs of electricity, cutting about 22 million tonnes of standard coal consumption and over 71.8 million tonnes of carbon dioxide.