On the edge of the Gobi Desert, at a place called Wuwei, China will soon test a safe, inexpensive nuclear energy, that will not need water to cool nuclear fuel rods nor uranium.
This experimental nuclear reactor uses thorium as a fuel and experts believe that China will be the first country to have a chance to commercialize the technology, German website Spektrum.de reported.
The reactor is unusual in that it has molten salts circulating inside it instead of water.
It has the potential to produce nuclear energy that is relatively safe and cheap, while also generating a much smaller amount of very long-lived radioactive waste than conventional reactors.
Operated by the Shanghai Institute of Applied Physics (SINAP), the reactor is designed to generate just two megawatts of thermal energy — enough to supply up to 1,000 households.
If the experiments are successful, however, China hopes to build a reactor with a capacity of 373 megawatts by 2030, which could supply hundreds of thousands of households with electricity.
According to the government of Gansu Province, construction was to be completed by early September and a trial run is slated later this month.
What exactly is thorium and why is it important?
A weakly radioactive, silvery metal that occurs naturally in rocks and is currently rarely used industrially, it is a by-product of the growing rare earth mining industry in China and is therefore an attractive alternative to imported uranium.
“Thorium is much more abundant than uranium, so using it would be a very useful technology for the next 50 or 100 years when uranium reserves run out,” said Lyndon Edwards, a nuclear engineer with the Australian Nuclear Science and Technology Organization in Sydney.
The reactor type is one of the “perfect technologies” that should help China achieve its goal of zero carbon emissions by around 2050, says energy modeler Jiang Kejun from the Energy Research Institute of the National Development and Reform Commission in Beijing.
The naturally occurring isotope thorium-232 cannot be fissioned, but when irradiated in a reactor it absorbs neutrons and forms uranium-233, a fissile material that generates heat.
Thorium has been tested as a fuel in other types of nuclear reactors in countries such as the US, Germany, and the UK, and is part of a nuclear program in India.
So far, however, it has not proven to be cost-effective because its extraction is more expensive than uranium and, unlike some naturally occurring uranium isotopes, it has to be converted into a fissile material.
Some researchers advocate thorium as a fuel because they believe that its waste products are less weapons-grade than uranium, making it safer and greener.
Unlike the uranium currently used in nuclear power plants, burning thorium does not create plutonium, a highly toxic chemical element.
There’s another advantage — 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.”
As a result, the reactors can be installed in isolated and arid regions… like the Gobi Desert.
Compared to light water reactors in conventional nuclear power plants, molten salt reactors, also known as molten salt reactors, work at significantly higher temperatures.
The result: You can generate electricity much more efficiently, says Charles Forsberg, a nuclear engineer at the Massachusetts Institute of Technology (MIT) in Cambridge.
According to Nature.com, China’s reactor will use fluoride-based salts, which melt into a colourless, transparent liquid when heated to about 450 ºC. The salt acts as a coolant to transport heat from the reactor core.
In addition, rather than solid fuel rods, molten-salt reactors also use the liquid salt as a substrate for the fuel, such as thorium, to be directly dissolved into the core.
Molten-salt reactors are considered to be relatively safe because the fuel is already dissolved in liquid and they operate at lower pressures than do conventional nuclear reactors, which reduces the risk of explosive meltdowns.
However, some critics say the feasibility of molten-salt reactors remains 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,” said Jean-Claude Garnier, head of France’s Alternative Energies and Atomic Energy Commission (CEA).
When China starts up its pilot reactor, it will be the first molten salt reactor to have been in operation since 1969. At that time, US researchers shut down their reactor at Oak Ridge National Laboratory in Tennessee.
It will also be the first liquid salt reactor to run on thorium.
China’s reactor will be “a test bed to do a lot of learning,” says Forsberg, from analysing corrosion to characterizing the radionucleotide composition of the mixture as it circulates.
“We are going to learn so much new science,” agrees Simon Middleburgh, a nuclear materials scientist at Bangor University, UK. “If they would let me, I’d be on the first plane there.”
Molten-salt reactors are just one of many advanced nuclear technologies China is currently investing in.
In 2002, an intergovernmental forum identified six promising reactor technologies to fast-track by 2030, including reactors cooled by lead or sodium liquids. China has programs for all of them.
Some of these reactor types could replace coal-fuelled power plants, says David Fishman, a project manager at the Lantau Group energy consultancy in Hong Kong.
“As China cruises towards carbon neutrality, it could pull out [power plant] boilers and retrofit them with nuclear reactors.”
But even if China ends up claiming victory, they should not rejoice too quickly, said Francesco D’Auria, nuclear reactor technology specialist at the University of Pisa: “The problem with corrosive products is that you don’t realize their damage until five to 10 years after.”
If it is successful, series production could start as early as 2030, officials said.
Note: Researchers directly involved with the reactor did not respond to requests for confirmation of the reactor design and the exact timing of the start of the tests.
Sources: Spektrum.de, Nature.com, France24