Chinese government scientists have unveiled plans for the first experimental nuclear reactor of its kind that does not require water for cooling.
The prototype molten salt nuclear reactor, which runs on liquid thorium rather than uranium, is expected to be safer than traditional reactors because thorium cools and solidifies quickly in air, meaning any potential leak in much less radiation the environment would give off compared to leaks from conventional reactors.
The prototype reactor is due to be completed next month, and the first tests will begin in September.
Since this type of reactor does not require any water, it can also be operated in desert regions. The location of the first commercial reactor, which is planned to be built by 2030, will be in the desert city of Wuwei, and the Chinese government plans to build more in the sparsely populated deserts and plains of western China, as well as in up to 30 square kilometers in countries that are part of China Belt and Road Initiative – a global investment program in which China will invest in the infrastructure of 70 countries.
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Chinese officials consider nuclear exports an important part of the Belt and Road program.
“Phasing out nuclear power has already become a government strategy, and nuclear exports will help streamline our export trade and free up domestic high-end manufacturing capabilities,” said Wang Shoujun, a standing committee member of the China People’s Political Consultative Conference ( CPPCC) – a political advisory body that acts as a liaison between the Chinese government and business interests, according to a report on the CPPCC website.
Thorium – a silvery, radioactive metal named after the Norse god of thunder – is much cheaper and more common than uranium and cannot easily be used to make nuclear weapons. The new reactor is part of Chinese President Xi Jinping’s efforts to make China climate neutral by 2060, according to the team at the Shanghai Institute of Applied Physics that developed the prototype. China currently contributes 27% of total global carbon emissions, the largest amount of any single country and more than the combined total of the developed world, according to a 2019 report by the U.S. Rhodium Group.
“Small-scale reactors have significant advantages in terms of efficiency, flexibility, and economy,” write Yan Rui, physics professor at the Shanghai Institute of Applied Physics, and colleagues in an article about the project published July 15 in Nuclear Techniques. “They can play a key role in the future transition to clean energy. Small reactors are expected to become widespread in the next few years.”
The Taklamakan Desert, also known as “The Sea of Death”, is the second largest sand desert in the world and a potential location for the waterless reactors. (Image Credit: Que Hure / VCG via Getty Images)
Instead of using fuel rods, molten salt reactors work by dissolving thorium in liquid fluoride salt before sending it to the reactor chamber at temperatures above 600 degrees Celsius. When bombarded with high-energy neutrons, thorium atoms split and release energy and even more neutrons through a process called nuclear fission. This starts a chain reaction in which heat is given off to the thorium salt mixture, which is then sent through a second chamber where the excess energy is extracted and converted into electricity.
Thorium reactors have long held an elusive pull for nuclear scientists. Just two positions to the left of uranium in the periodic table of the chemical elements is almost all of the degraded thorium, thorium-232, the isotope used in nuclear reactions. In contrast, only 2% to 3% of all uranium mined is the fissile uranium-235 used in traditional nuclear reactors. This makes thorium a much more abundant source of energy.
The benefits of thorium don’t stop there. The waste products from uranium-235 nuclear reactions remain highly radioactive for up to 10,000 years and include plutonium-239, the main constituent of nuclear weapons. Ordinary nuclear waste must be housed in lead containers, isolated in secure facilities, and subjected to rigorous controls to ensure that it does not fall into the wrong hands. In contrast, the main by-products of a thorium nuclear reaction are uranium-233, which can be recycled in other reactions, and a number of other by-products with an average “half-life” (the time it takes for half the radioactive atoms of a substance) to be in a non-radioactive state) of only 500 years.
After the 2 gigawatt prototype was tested in September, China plans to build its first commercial thorium reactor. With a height of only 3 meters and a width of 2.5 meters, the researchers can generate 100 megawatts of electricity, enough to supply 100,000 people with electricity. Still, it has to be paired with other devices like steam turbines to make usable electricity.
The molten salt reactor concept was first developed in 1946 as part of a plan by the US Air Force’s predecessor to develop a nuclear-powered supersonic jet.
However, the experiment ran into too many problems, such as hot salt corrosion and cracks in pipes, and the project was abandoned in 1954. Since then, several groups have attempted to create workable molten salt reactors, including an experimental reactor at Oak Ridge National Laboratory in Tennessee, but thorium’s weak radioactivity makes it very difficult for nuclear fission reactions to build up to sustainable levels without the addition of uranium.
It is not yet clear how Chinese researchers solved these technical problems.
China’s efforts are the most advanced of many other new attempts to build thorium reactors, including one called Sodium, which is planning to build a pilot facility in Wyoming and has financial backing from Bill Gates and Warren Buffett.
Nuclear reactors aren’t the only technology China is investing in to become climate neutral. The Baihetan Dam, the second largest hydroelectric power plant in the world after China’s Three Gorges Dam, went online in June and has a power generation capacity of 16 gigawatts. UK energy consultancy Wood Mackenzie estimates that China will add 430 gigawatts of new solar and wind capacity over the next five years.
Even if China positions itself as a world leader in the fight against climate change, the country is already acutely affected by extreme weather events. Severe flooding in Henan province this week displaced around 100,000 people and killed at least 33, CNN reported. The weather bureau in Zhengzhou, the capital of the region, said the three rainy days had reached the level that can only be observed “once in 1,000 years”.
Originally published on Live Science.
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