China sees thorium breakthrough in Gobi desert
On the edge of the Gobi Desert, in a place called Wuwei, China will soon be testing safe, inexpensive nuclear power that does not require water to cool nuclear fuel rods or uranium.
This experimental nuclear reactor uses thorium as fuel and experts believe that China will be the first country to commercialize the technology, the German website Spektrum.de reported.
The reactor is unusual in that molten salts circulate in it instead of water.
It has the potential to produce relatively safe and inexpensive nuclear power while producing a much smaller amount of very long-lived radioactive waste than conventional reactors.
The reactor operated by the Shanghai Institute of Applied Physics (SINAP) is supposed to generate only two megawatts of thermal energy – enough to supply up to 1,000 households.
However, if the experiments are successful, China hopes to build a 373 megawatt reactor by 2030 that could power hundreds of thousands of households.
According to the government of Gansu Province, the construction work should be completed in early September, with a trial run this month.
What exactly is thorium and why is it important?
As a weakly radioactive, silvery metal that occurs naturally in rocks and is currently hardly used industrially, it is a by-product of the growing rare earth mining in China and thus an attractive alternative to imported uranium.
“Thorium is much more abundant than uranium, so it would be a very useful technology for the next 50 or 100 years when uranium reserves are depleted,” 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 CO2 emissions by around 2050, says energy modeler Jiang Kejun from the Energy Research Institute of the National Development and Reform Commission in Beijing.
China is developing a thorium-based reactor in the Gobi desert. Credit: US Department of Energy.
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 economical because it is more expensive to extract than uranium and, unlike some naturally occurring uranium isotopes, it must 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 more environmentally friendly.
Unlike uranium, which is currently used in nuclear power plants, burning thorium does not produce plutonium, a highly toxic chemical element.
Another advantage: This type of reactor does not have to be built near watercourses, since the molten salt itself “serves as a coolant, in contrast to conventional uranium power plants, which require huge amounts of water to cool their reactors”.
This allows the reactors to be installed in remote and arid regions … like the Gobi Desert.
Compared to light water reactors in conventional nuclear power plants, molten salt reactors, also called 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 uses fluoride-based salts that melt into a colorless, transparent liquid when heated to around 450 ° C. The salt acts as a coolant to transport heat out of the reactor core.
In addition, instead of solid fuel rods, molten salt reactors also use the liquid salt as a substrate for the fuel, such as thorium, which is dissolved directly in the core.
Molten salt reactors are considered relatively safe because the fuel is already dissolved in liquid and they operate at lower pressures than conventional nuclear reactors, reducing the risk of explosive core meltdowns.
However, some critics say the feasibility of molten salt reactors remains questionable as it raises further technical problems.
“At very high temperatures, the salt can corrode the structures of the reactor, which must be protected in some way,” said Jean-Claude Garnier, head of the French Commission for Alternative Energy and Atomic Energy (CEA).
When China starts up its pilot reactor, it will be the first molten salt reactor to have been in operation since 1969. US researchers shut down their reactor in the 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 ground for learning a lot,” says Forsberg, from analyzing the corrosion to characterizing the radionucleotide composition of the circulating mixture.
“We’re going to learn so much new science,” agrees Simon Middleburgh, a nuclear materials scientist at Bangor University, UK. “If they would let me, I would be on the first plane there.”
Molten salt reactors are just one of many advanced nuclear technologies that China is currently investing in.
In 2002, an intergovernmental forum identified six promising reactor technologies to be accelerated by 2030, including reactors that are cooled with lead or sodium liquids. China has programs for all of them.
Some of these reactor types could replace coal-fired power plants, says David Fishman, project manager at the energy consultancy Lantau Group in Hong Kong.
“If China moves towards CO2 neutrality, it could withdraw” [power plant] Boilers and retrofit them with nuclear reactors. “
But even if China wins in the end, they shouldn’t rejoice too quickly, said Francesco D’Auria, a specialist in nuclear reactor technology at the University of Pisa: “The problem with corrosive products is that their damage is not done until five before 10 years later. “
If successful, series production could start as early as 2030, it said.
Note: Researchers directly involved with the reactor did not respond to requests to confirm the reactor design and the exact timing of the start of the tests.
Sources: Spektrum.de, Nature.com, France24