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Are There Safer Ways To Produce Nuclear Energy?

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While the United States is working to get four new nuclear units up-and-running in Georgia and South Carolina, it is also partnering with China and Canada to operate some highly advanced next-generation nuclear plants.

"Molten salt reactors" that burn “thorium” are not only safer but they also create less radioactive waste than uranium. As for China, its next-generation 100 megawatt smaller plant could be operational within a decade. Similarly, the national labs here are partnering with a Canadian firm to build such a modular reactor -- an effort that is expected to produce an engineering design in a few years, and a commercial reactor in 10 years.

“While simple black and white statements about thorium versus uranium are the easiest point to get across, the real story is about a particular type of reactor, called molten salt reactors whose main feature is a liquid fuel form which gives outstanding potential benefits in safety, fuel economy and waste issues,” says David LeBlanc, an expert with Terrestrial Energy in Canada, which is working with the U.S. Department of Energy’s Oak Ridge National Laboratory in Tennessee on its project.

“Molten salt reactors are all-liquid fuel, or ‘pre-melted,’ which offers great potential for reactor safety and cost innovation,” adds LeBlanc, in prior email exchanges. “They do not need to keep coolant flowing to the reactor because the fuel itself is the coolant.”

By contrast, solid-fuel reactors burning uranium are now prevalent. Once uranium is used, it becomes highly radioactive. That waste is then cooled in spent fuel pools before it is stored in above-ground, concrete-encased steel caskets. As the world learned from both Ukraine's Chernobyl and Japan's Fukushima accidents in 1986 and 2011, respectively, that spent fuel could escape and do irreparable harm.

Thorium’s proponents point out that molten salt reactors that burn that fuel won’t “meltdown” because, unlike today’s high-pressured units, they are low-pressured and won’t vaporize. It is also far more abundant in nature than uranium.

China has the most aggressive research program into molten salt reactors and thorium. But so do India and Canada. In China’s case, it is spending hundreds of millions of dollars to try and commercialize this technology for two different plants using molten-salts.

“The first will use solid fuel but be cooled by low pressure molten salts,” says Terrestrial's LeBlanc. “The second is a true molten salt reactor whereby the fuel itself is in the form of a liquid salt.”

He adds that two molten salt reactors were built and operated in the United States in the 1950s and 1960s. However, the technology was shelved in the 1970s. Now, with China’s well-funded program, those molten salt reactors that run on thorium have a new life.

But don’t expect those advanced reactors to supplant solid-fuel units that run on uranium: The supply chain is now fully stocked and includes everything from uranium suppliers to reactor designers. However, if China and Canada can successfully demonstrate a thorium-fueled reactor, the paradigm could change.

“In 2012, I visited the Chinese molten salt reactor labs near Shanghai and it was clear that they are taking the time to get the basics right and to build a strong program from the ground up,” says David Martin, deputy director of research for the Weinberg Foundation in London, in a series of emailed questions.

“These thorium molten salt reactors offer great benefits but they are totally different from current reactors,” he adds. “So China will have to train a whole cohort of technicians, scientists and regulators to understand the reactor.”

To be clear, the U.S. nuclear fleet uses second-generation light water, solid fuel reactors. They operate, on average, at more than 90 percent capacity.

“Third-generation” light water reactors are going up mostly in China and India and they are the kind that are now getting constructed by Georgia-based Southern Company and South Carolina-based Scana Corp. Those third-generation reactors have superior fuel technology, thermal efficiency and safety features.

The next-generation reactors, called “fourth-generation,” are those that run at much higher temperatures. They are even more efficient than those in the third-generation, allowing them to produce more electricity at less cost.

For what it worth, a French nuclear safety watchdog group, IRSN, has said that it is “unable to determine” at this early point whether next-gen reactors are “significantly safer” than current nuclear designs. Meantime, other skeptics say that it is difficult to maintain high thermal efficiencies, which diminishes the economic case for those fourth-gen reactors over today’s technologies. As such, molten salt reactors can be more expensive than those in use now.

Thorium is most suited to run in fourth-generation “liquid fuel” reactors, which  operate at lower pressures and which are therefore inherently safer. Such molten salt reactors must reach high level temperatures to melt a salt solid. That liquid and fuel mixture is then used as a coolant in the fuel cycle.

“If China does build this reactor, it will still make economic and political sense to maintain the existing uranium-fueled reactors and to run them for as long as possible,” says Weinberg’s Martin. But if nuclear energy should undergo a renaissance, he adds, then it would bolster the need for molten salt reactors using thorium.

“If China successfully builds a thorium-fueled molten salt reactor, it will leapfrog the current generation of reactors,” Martin concludes. “This is the kind of urgency we need if we are to truly fight climate change and air pollution.”