Why China is developing a game-changing thorium-fuelled nuclear reactor
China is poised to test a thorium-powered nuclear reactor in September, the world’s first since 1969. The theory is that this new molten-salt technology will be “safer” and “greener” than regular uranium reactors, and so could help Beijing meet its climate goals. Yet is the country's investment in this also geostrategic?
A new page in the history of nuclear energy could be written this September, in the middle of the Gobi Desert, in the north of China. At the end of August, Beijing announced that it had completed the construction of its first thorium-fuelled molten-salt nuclear reactor, with plans to begin the first tests of this alternative technology to current nuclear reactors within the next two weeks.
Built not far from the northern city of Wuwei, the low-powered prototype can as yet only produce energy for around 1,000 homes, according to the scientific journal Nature.
But if the upcoming tests succeed, Chinese authorities will start a programme to build another reactor capable of generating electricity for over 100,000 homes. Beijing could then become an exporter of a reactor technology that has been the subject of much discussion for over 40 years, according to French financial newspaper Les Echos.
Lower accident risks?
The Chinese reactor could be the first molten-salt reactor operating in the world since 1969, when the US abandoned its Oak Ridge National Laboratory facility in Tennessee.
“Almost all current reactors use uranium as fuel and water, instead of molten salt and thorium," which will be used in China’s new plant, Jean-Claude Garnier, head of France’s Alternative Energies and Atomic Energy Commission (CEA), told FRANCE 24.
These two "new" ingredients were not chosen by accident by Beijing: molten-salt reactors are among the most promising technologies for power plants, according to the Generation IV forum – a US initiative to push for international cooperation on civil nuclear power.
With molten-salt technology, "it is the salt itself that becomes the fuel", Sylvain David, research director at the French National Centre for Scientific Research (CNRS) and nuclear reactors specialist, explained in a FRANCE 24 interview. The crystals are mixed with nuclear material – either uranium or thorium – heated to over 500°C to become liquid, and are then be able to transport the heat and energy produced.
Theoretically, this process would make the installations safer. "Some accident risks are supposedly eliminated because liquid burning avoids situations where the nuclear reaction can get out of control and damage the reactor structures," Jean-Claude Garnier added.
There's another advantage for China: this type of reactor does not need to be built near watercourses, since the molten salts themselves "serve as a coolant, unlike conventional uranium power plants that need huge amounts of water to cool their reactors", French newspaper Les Echos noted. As a result, the reactors can be installed in isolated and arid regions… like the Gobi Desert.
China's plentiful supply
Beijing has also opted to use thorium rather than uranium in its new molten-salt reactor, a combination that has drawn attention from experts for years. This is mostly because “there is much more thorium than uranium in nature”, Francesco D’Auria, nuclear reactor technology specialist at the University of Pisa, told FRANCE 24.
In addition, thorium belongs to a famous family of rare-earth metals that are much more abundant in China than elsewhere; this is the icing on the cake for Chinese authorities, who could increase its energy independence from major uranium exporting countries, such as Canada and Australia, two countries whose diplomatic relations with China have collapsed in recent years.
Beijing’s investment is also a long-term one. “For now, there is enough uranium to fuel all operating reactors. But if the number of reactors increases, we could reach a situation where supply would no longer keep up, and using thorium can drastically reduce the need for uranium. That makes it a potentially more sustainable option," Sylvain David explained.
A 'greener' nuclear energy?
According to supporters of thorium, it would also a "greener" solution. Unlike the uranium currently used in nuclear power plants, burning thorium does not create plutonium, a highly toxic chemical element, Nature pointed out.
With so many positives on their side, why are molten salts and thorium only being used now? “Essentially because uranium 235 was the natural candidate for nuclear reactors and the market did not look much further," Francesco D'Auria added.
Radiation, corrosion and... nuclear weapons
Among the three main candidates for nuclear reaction – uranium 235, uranium 238 and thorium – the first is “the only isotope naturally fissile”, Sylvain David explained. The other two must be bombarded with neutrons for the material to become fissile (able to undergo nuclear fission) and be used by a reactor: a possible but more complex process.
Once that is done on thorium, it produces uranium 233, the fissile material needed for nuclear power generation. That then becomes another problem with thorium: "The radiation emitted by uranium 233 is stronger than that of the other isotopes, so you have to be more careful," Francesco D'Auria warned.
The feasibility of molten-salt reactors is also questionable as it creates further technical problems. "At very high temperatures, the salt can corrode the reactor’s structures, which need to be protected in some manner," Jean-Claude Garnier explained.
The stakes are clearly high for the Chinese tests and they will be watched very closely around the world in order to see how Beijing hopes to overcome these obstacles. But even if China ends up claiming victory, they should not rejoice too quickly, Francesco D’Auria said: "The problem with corrosive products is that you don't realise their damage until five to 10 years after."
Moreover, the expert claims there is no reason to celebrate a nuclear reactor that not only produces energy, but also uranium 233. "This is an isotope that does not exist in nature and that can be used to build an atomic bomb," pointed out Francesco D'Auria.
As such, China could end up revolutionising the nuclear industry but, at the same time, they might once more alarm supporters of non-proliferation around the world.
This story was adapted from the original in French.
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