BEIJING -- China's state-owned power plant operators are introducing safer, more efficient nuclear reactors as the government looks to raise its nuclear power capacity by 50% by 2020 to reduce its reliance on coal.

So-called generation III plus reactors have safety features that automatically shut down the unit if the power is cut off. At least three advanced reactors will be operating in China by the end of the year, and more are on the way.

In Zhejiang Province, China National Nuclear Power, a unit of China National Nuclear Corp., began commercial power generation of its Sanmen-1 reactor in September, becoming the first company in the world to operate an AP1000 pressurized water reactor designed by Westinghouse Electric of the U.S.

Construction began in 2009. In April, the reactor received regulatory approval and was loaded with fuel. The 1,250 megawatt reactor was hooked up to the grid in June and was test run for 168 consecutive hours.

State Power Investment Corp.'s Haiyang plant in Shandong Province also has a Westinghouse AP1000 reactor, which began trial runs in August. Last month the advanced 1,250 MW reactor was declared ready for commercial operation. Eventually the power station will have six AP1000 reactors.

China General Nuclear Power Group's Taishan-1 in Guangdong Province is a European-type pressurized water reactor, or EPR, designed by French company Areva. The reactor was successfully powered up in June and trial runs are underway. If they go as planned, 1,750 MW plant will begin commercial operation by the end of the year.

According to China's National Energy Administration, more than 40 nuclear reactors are operating in the country, with a total capacity of 38,000 MW as of the end of August. Although that represents a near tripling of China's nuclear capacity compared with just five years earlier, nuclear power still accounted for less than 4% of the country's total output in 2017, while coal-fired plants had a 70%-plus share.

China's President Xi Jinping aims to raise the country's nuclear power output to 58,000 MW by around 2020, and to 150,000 MW by 2030, which would make it the world's biggest generator of nuclear power, ahead of the U.S. If it reaches that goal, nuclear power will grow to 8% of China's forecast electricity output.

Beijing is keen to develop its own nuclear reactor technology. Its Hualong One is a domestic version of the pressurized water reactor design, which it developed through its experience building and operating plants in China. It also incorporates technologies from overseas.

Even as China applies itself to developing nuclear power, the German and U.S. governments are wary of cooperating too closely, despite the business opportunities, due to concerns over technology leaks and possible military applications.

Plans are underway to build a number of Hualong One reactors, including at the Fuqing power plant in Fujian Province in China's southeast, and at the Fangchenggang nuclear project in the Guangxi-Zhuang Autonomous Region. China is also promoting exports of its homegrown advanced reactor in the U.K., Pakistan and elsewhere.

The U.S. Department of Energy in October announced new restrictions on exports of civilian nuclear technology to China. The German government in August blocked an attempt by Yantai Taihai Group, a metalworking and chemical company based in China's Shandong Province, to buy German precision equipment maker Leifeld Metal Spinning, whose machines can be used to fabricate nuclear plant components.

Although the new U.S. rules will not affect Westinghouse's AP1000 projects in China, Chinese companies hoping to use new American technology will have to offer more transparency about how it will be used.

Striking a balance between security and commercial interests will also be challenging for Washington. According to Chinese news outlets, U.S. exports to China of nuclear equipment totaled $170 million in 2017, making it the second-largest buyer of U.S. products after the U.K.