China has achieved the first-ever thorium-to-uranium nuclear fuel conversion in its experimental Thorium Molten Salt Reactor (TMSR). The Shanghai Institute of Applied Physics (SINAP) of the Chinese Academy of Sciences said it had obtained valid experimental data following thorium fuel loading, confirming the technical feasibility of thorium utilisation in a molten-salt reactor nuclear energy system.
The 2 MW TMSR, built by SINAP in collaboration with other Chinese institutions in Wuwei City in Gansu Province, is currently the only operational molten-salt reactor in the world loaded with thorium fuel. The realisation of thorium-uranium conversion marks a milestone in TMSR development, providing core technical support and a feasible solution for China’s large-scale development and utilisation of thorium resources, and for the future progress of advanced nuclear energy systems.
“Featuring thorium-uranium conversion, it is the first time in the world that thorium was added to a molten-salt reactor, demonstrating the feasibility of our thorium resources utilisation. It is also a unique thorium-uranium cycle research platform in the world, laying a solid foundation for the construction of demonstration reactors and relevant commercial development in the future,” said SINAP Director Dai Zhimin.
SINAP said the TMSR programme was launched in 2011, achieving major progress from laboratory research to the engineering verification of core materials, equipment and technologies. With domestically developed core equipment and an independent supply chain, China has established complete TMSR technology and industrial chains in basic terms.
This aligns with China’s abundant thorium reserves and also allows for deep integration with other industries. These include solar power, wind power, high-temperature molten-salt energy storage, high-temperature hydrogen production, coal chemical engineering and petrochemical engineering. This will facilitate the development of a complementary, low-carbon, integrated energy system.
SINAP will work with leading energy companies to consolidate the TMSR industrial and supply chains and accelerate technology iteration and engineering application. The ultimate goal is to construct a 100 MW demonstration project and realise its demonstration application by 2035.
“Wind energy and solar energy are subject to weather conditions. Therefore, if we build molten-salt reactors in inland areas, they can play a role in balancing and stabilising the power grid. So, we chose to build the reactor in Wuwei, Gansu Province, to create a multi-energy mutual complementation system,” said Li Qingnuan, deputy director of SINAP.
“Thorium is related to rare earths which are in abundant supply in China, which means a sufficient reserve of thorium,” said Dai. “Therefore, the research on thorium-based molten salt reactors is highly suitable for our national conditions. If all the electricity in our country were generated with thorium resources, it could last thousands of years, fully ensuring our energy security and independence.”
The global nuclear power sector generally uses uranium-235 as reactor fuel, but its reserves in nature are very limited. China’s uranium resources are especially scarce, so it’s highly dependent on imports for nuclear raw materials, while demand grows with the industry’s rapid development. To find an alternative to uranium-235, the Chinese researchers looked to the TMSR that can convert thorium-232, which is rich in natural reserves, into uranium-233 by absorbing neutrons, creating a sustainable nuclear fuel supply, SINAP noted.
The TMSR programme was launched in 2011. To prevent possible leakage of radioactive substances, the scientists innovatively designed the integrated structure of the reactor, integrating core equipment such as the reactor core, fuel salt pump, and heat exchanger within the main reactor vessel. “With heat exchangers inside the reactor, the molten salt coolant never comes out of the reactor body. We also have a safe container outside the reactor body, so there’s a multi-layer protection to make sure radioactive materials don’t leak,” explained Dai.
“Even if there occurs an accident involving the entire reactor, only a very small amount of fission products may be discharged. As the byproducts have already gone through our treatment systems during normal operations, there won’t be much leakage of radioactive materials even in extreme accident situations,” said SINAP Deputy Director Li.
