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Fail-Safe Nuclear Power

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.

The Shanghai Institute’s effort to develop molten-salt reactors, a technology that has sat all but forgotten in the United States for decades, reflects just how daring China’s nuclear ambitions are. Already, the government has invested some two billion Chinese renminbi ($300 million) over the last five years in molten-salt R&D. Building actual plants will require tens of billions more. As with other innovative nuclear technologies in development around the world, there are few guarantees: though people have run small, experimental molten-salt reactors, no one’s ever actually built one at utility scale and hooked it up to the grid. Yet the Chinese government expects to have a commercial-size plant up and running within 15 years, helping to revive the beleaguered nuclear power industry.

The first experiments with molten-salt reactors were carried out at Oak Ridge National Laboratory, in Tennessee, under its director Alvin Weinberg in the late 1950s. Today’s Chinese program, in fact, is the fruit of a unique and somewhat controversial partnership between Oak Ridge and the Shanghai Institute. The U.S. research program went on for more than a decade but was eventually shut down in favor of the technology used in the vast majority of nuclear power plants today. In retrospect, that decision contributed not only to the demise of a promising nuclear technology but also to the long stagnation of the industry.

Today, though, the world needs nuclear energy more than ever if we are to limit climate change. According to the International Energy Agency, the world’s nuclear capacity needs to more than double by midcentury if we are to stay within 2 °C of warming. As it stands now, that seems unlikely. Several countries, including China and India, have embarked on massive nuclear power build-outs, but most will entail big, conventional reactors—technology that is too expensive for much of the rest of the world. Even countries, such as Germany, that can afford nuclear power are phasing it out because they fear another disaster. That makes the fail-safe nuclear power plants being developed at the Shanghai Institute of paramount urgency.

After my virtual tour, Kun Chen, one of the molten-salt program’s lead scientists, walked me back to the institute’s main administration building. Snow had fallen overnight, and it was bitterly cold. In the auditorium a small crowd of staffers had gathered for a talk by Xu Hongjie, the director of the molten-salt program. It was the week before the long lunar new year holiday, and the institute’s annual banquet was being held that night. Xu spoke for more than two hours about the history of molten-salt technology and its prospects for the future.

“This has been China’s dream for a half-century,” he said. “Previously, we lacked the necessary knowledge and skills to make it a reality. Now we have the resources and the technology and the expertise. Now we can do it.”

Chain reactions

Alvin Weinberg first came to Oak Ridge in 1945, just after its laboratories had been built in the northern Tennessee hills to make weapons-grade uranium and plutonium. A veteran of the Manhattan Project, Weinberg became director of the rapidly growing national lab in 1955 and held the position until 1973. He was a pioneering nuclear physicist and a philosopher of nuclear power who used the phrase “Faustian bargain” to describe the tension between industrialized society’s thirst for abundant energy and the extreme vigilance needed to keep nuclear power safe. To make this energy source both clean and extremely cheap, he believed, the link between nuclear power and nuclear weapons would have to be severed. And the way to break that link was the thorium molten-salt reactor.

Read full article at Technology Review