The logo of Westinghouse Electric Corp. is pictured at the World Nuclear Exhibition (WNE), the trade fair event for the global nuclear community in Villepinte near Paris, France, June 26, 2018. REUTERS/Benoit Tessier

SHANGHAI (Reuters) - China’s fourth Westinghouse-designed AP1000 reactor went into full operation after a trial run this week, the operator said, marking the completion of the first phase of the project after years of delays.

China signed a deal with the U.S. firm in 2007 to build four reactors, hoping to create a platform for Beijing’s ambitious nuclear power expansion plans, but the roll-out of the unproven “third-generation” technology has been beset by safety concerns and design problems.

The second unit of the Haiyang nuclear power project on the eastern coast of China’s Shandong province is now ready to go into full commercial operation after 168 hours of full-load operations, China’s State Power Investment Corp said in statement on Thursday.

China put the world’s first AP1000 into operation at Sanmen in Zhejiang province last September, four years later than originally scheduled. Two more went into operation at Sanmen and Haiyang later in the year.

The AP1000 is designed by U.S.-based Westinghouse, which was acquired by Brookfield Business Partners BBU_u.TO from Japan's Toshiba last August following bankruptcy restructuring.

The completion of the project brings China’s total nuclear capacity up to 45 gigawatts, with 46 reactor units in operation throughout the country. Nuclear makes up about 2.5 percent of the country’s generation capacity.

China has scaled back the pace of new reactor approvals and no new conventional project has been given the go-ahead in more than three years. It is now expected to fall short of its 2020 target to have 58 gigawatts of working capacity and another 30 gigawatts under construction.

At the government’s annual energy meeting in December, officials made no commitments to approving and building any new projects in 2019, saying only that projects now under construction would be “pushed forward in an orderly manner”.