China is expected to start building at least five nuclear reactors in 2015 while facing a further delay at a plant that had been slated to start this year.

The Sanmen project in the eastern province of Zhejiang is expected to come online at the beginning of 2016 after problems were found in the main pump during testing, said Wang Zhongtang, chief engineer of China's State Nuclear Power Technology Corp. The Westinghouse Electric Co.-designed plant is the world's first AP1000 reactor.

China plans to expand atomic capacity threefold by 2020 in a renewed nuclear push after the country stopped approving new projects following the Fukushima meltdown in Japan in March 2011. The country's reactor-building program is now the world's most ambitious, according to the International Energy Agency.

The five projects represent more than 5 gigawatts of capacity, Shen Lixin, deputy secretary general of the Chinese Nuclear Society, said in Beijing on Thursday. China will probably keep up the pace of construction next year, said Shen, whose organization acts as a liaison between the government and academics.

Nuclear power is among the clean energies China hopes to rely on in a bid to cap carbon emissions by 2030. Atomic energy now accounts for just 2 percent of the country's total power generation, the IEA estimates.

Asia represents the future for nuclear energy. The region has 47 reactors under construction and a further 142 forecast by 2030, the World Nuclear Association said Thursday in a statement. Asian investment in nuclear projects could reach $781 billion during the period, the WNA said.

China has 22 reactors in operation and another 26 under construction, Shen said.