The outer containment dome of the Karachi unit 2 nuclear reactor in Pakistan was successfully installed on Monday, a milestone marking the end of its general construction work, said China National Nuclear Corp, one of the country's largest nuclear power companies.

The installation of the outer containment dome of Karachi unit 2, the first export of China's Hualong One pressurized water reactor design, a domestically developed third-generation reactor design, will be followed up by containment and heat tests, it said.

CNNC has four HPR1000 units under construction around the world, which is the world's only third-generation pressurized water reactor nuclear power project constructed according to schedule.

Analysts said the successful installation of the outer containment dome will speed up nuclear cooperation between China and countries and regions participating in the Belt and Road Initiative, boosting confidence in China's Hualong One technology.

After years of development, China has risen from a nuclear energy novice to being a world leader in nuclear plant development globally, said Joseph Jacobelli, an independent energy analyst and Asia-Pacific CEO of clean energy producer Joule Power.

"I believe the nation's nuclear power technology companies should become major suppliers on the global stage as they develop the technologies rapidly, yet cautiously," he said.

"The massive amount of new capacity to be added in China over the next two decades will give them even more scope to test out their technologies. It is not a question as to whether they will join the top global ranks but more when they will do so."

Construction of Karachi unit 2 started in 2015 and is scheduled for commercial operation in 2020, said the company.

According to CNNC, the country's self-developed third-generation nuclear power technology adopts a double containment design, with the outer containment providing protection for the primary containment.

The outer containment dome is a 366-metric-ton multi-surface shell made up of 63 prescribed components.

Unit 5 of CNNC's Fuqing nuclear power plant, the nation's first demonstration nuclear power project using Hualong One technology, has recently succeeded in inverse power transmission, laying a solid foundation for future fuel loading, power generation and transmission for the unit.

China has charted plans to raise its total installed nuclear capacity to 58 gigawatts by 2020, while it also aims to have another 30 gigawatts under construction by the end of 2020.