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China's experiment with a reactor could be commercialized if it is successful, which would help China meet its climate goals.
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China already has over 50 nuclear power plants. However, the first experimental thorium reactor will be built in Wuwei. Credit: Costfoto/Barcroft Media/Getty
Scientists are excited by the possibility of a nuclear reactor that uses thorium for fuel. These tests will be conducted in China. Experts say China will be the first country to commercialize the radioactive element, despite it having been tested in reactors in the past.
It is unique in that it uses molten salts instead of water. The reactor has the potential to generate nuclear energy that is safe and inexpensive, as well as a smaller amount of radioactive waste than other conventional reactors.
According to the Gansu provincial government, construction of the experimental thorium-reactor in Wuwei (on the outskirts the Gobi Desert) was expected to be complete by August. Trial runs were scheduled for August.
The weakly radioactive and silvery-colored metal thorium is found in rocks but has limited industrial applications. Researchers say it is a waste product from the China's growing rare-earth mining sector and therefore a viable alternative to imported Uranium.
Potential for greatness
Lyndon Edwards is a nuclear engineer at Sydney's Australian Nuclear Science and Technology Organisation. Thorium is more abundant than uranium so it would be very useful to have this technology in 50 to 100 years, when uranium resources start to run out. He says that the technology will be difficult to develop and is therefore important to begin work now.
China's molten-salt-reactor programme was launched in 2011 by Ritsuo Yoshioka (ex-president of the International Thorium Molten-Salt Forum, Oiso, Japan), who worked closely with Chinese researchers.
The Wuwei reactor, operated by the Shanghai Institute of Applied Physics(SINAP), is capable of producing just 2 megawatts of heat energy. This is enough to power approximately 1,000 homes. China plans to build a 373 megawatt reactor by 2030 if the experiments prove successful. This could be enough power for hundreds of thousands of homes.
These reactors are among the best technologies to help China achieve its goal of zero carbon emission by 2050, according to Jiang Kejun, an energy modeller at the Energy Research Institute of the National Development and Reform Commission.
Although thorium-223 is not a naturally occurring isotope, it can undergo fission when irradiated in reactors. However, it absorbs neutrons to create uranium-233 which is a fissile substance that generates heat.
The use of thorium as a fuel has been proven in several countries, including the United States, Germany, and the United Kingdom. It is also part of an Indian nuclear program. It is not cost-effective as it is more costly to extract than uranium. Also, unlike other naturally occurring uranium isotopes, it must be made into a fissile substance.
While some researchers favor thorium's use as a fuel, they argue that its waste products are less likely to be weaponized than those of uranium. Others disagree and say that there are still risks.
Source: US Department of Energy/International Atomic Energy Agency
The past is blasting back
China's experimental reactor will become the first molten salt reactor to be operational since 1969 when it was shut down by US researchers at Oak Ridge National Laboratory, Tennessee. It will also be the first molten salt reactor to be powered by thorium. SINAP researchers have said that the Chinese design is similar to Oak Ridge's, but it uses decades of innovation in manufacturing, materials, and instrumentation.
China researchers directly involved in the reactor's design did not respond to inquiries about confirmation and when exact tests will start.
Molten-salt reactors are much more efficient than light-water reactors found in conventional nuclear power plants. This is according to Charles Forsberg, a Massachusetts Institute of Technology nuclear engineer.
China's reactor will be using fluoride-based sodium salts. These melt to a transparent, colourless liquid at temperatures of around 450 C. The coolant used to transport heat from core of reactor is the salt. Molten-salt reactors use liquid salts instead of solid fuel rods. The liquid salt is used to dissolve the fuel into the core.
Because the fuel is already in liquid form, molten-salt reactors can be considered relatively safe. They also operate at lower pressures that conventional nuclear reactors. This reduces the chance of an explosion.
Yoshioka states that many countries are developing molten salt reactors to produce cheaper electricity from uranium, or to use plutonium waste from light-water reactors for fuel. However, China is the only one trying to use thorium fuel.
Thorium pellets at Mumbai's Bhabha Atomic Research Centre, India. Credit: Pallava Bagla/Corbis/Getty
Reactors of the next generation
Forsberg says China's reactor will serve as a laboratory to learn a lot, from studying corrosion to analyzing the radionucleotide content of the mixture as it circulates.
Simon Middleburgh (a Bangor University nuclear materials scientist) agrees that we will learn so many new science. If they allowed me, I would be on the first plane.
China's reactor could be operational for months. Middleburgh says that if something goes wrong along the way, it is impossible to continue and must stop and restart. One example is that pumps could fail, pipes might corrode, or a blockage may occur. Scientists are optimistic about their chances of success.
China is investing in many nuclear technologies, including molten-salt reactors. An intergovernmental forum in 2002 identified six promising technologies for fast-tracking by 2030. These included reactors that are cooled with lead or sodium liquids. China has programs for each of these technologies.
David Fishman, a project manager at Lantau Group's energy consultancy in Hong Kong, said that some of these reactor types could be used to replace coal-fuelled power stations. China is on its way to carbon neutrality and could remove boilers from power plants and retrofit them using nuclear reactors.