In February I flew through the interior of a machine that could represent the future of nuclear power. I was on a virtual-reality tour at the Shanghai Institute of Applied Physics in China, which plans in the next few years to build an experimental reactor whose design makes a meltdown far less likely. Inside the core—a superhot, intensely radioactive place where no human will ever go—the layers of the power plant peeled back before me: the outer vessel of stainless steel, the inner layer of a high-tech alloy, and finally the nuclear fuel itself, tens of thousands of billiard-ball-size spheres containing particles of radioactive material.

Given unprecedented access to the inner workings of China’s advanced nuclear R&D program, I was witnessing a new nuclear technology being born. Through the virtual reactor snaked an intricate system of pipes carrying the fluid that makes this system special: a molten salt that cools the reactor and carries heat to drive a turbine and make electricity. At least in theory, this type of reactor can’t suffer the kind of catastrophic failure that happened at Chernobyl and Fukushima, making unnecessary the expensive and redundant safety systems that have driven up the cost of conventional reactors. What’s more, the new plants should produce little waste and might even eat up existing nuclear waste. They could run on uranium, which powers 99 percent of the nuclear power plants in the world, or they could eventually run on thorium, which is cleaner and more abundant. The ultimate goal of the Shanghai Institute: to build a molten-salt reactor that could replace the 1970s-era technology in today’s nuclear power plants and help wean China off the coal that fouls the air of Shanghai and Beijing, ushering in an era of cheap, abundant, zero-carbon energy.

Over the next two decades China hopes to build the world’s largest nuclear power industry. Plans include as many as 30 new conventional nuclear plants (in addition to the 34 reactors operating today) as well as a variety of next-generation reactors, including thorium molten-salt reactors, high-temperature gas-cooled reactors (which, like molten-salt reactors, are both highly efficient and inherently safe), and sodium-cooled fast reactors (which can consume spent fuel from conventional reactors to make electricity). Chinese planners want not only to dramatically expand the country’s domestic nuclear capacity but also to become the world’s leading supplier of nuclear reactors and components, a prospect that many Western observers find alarming.