By Wu Wanzhen in Wuwei and Li Menghan in Beijing

A  researcher works at the charging-sampling hot cell of the experimental  Thorium Molten Salt Reactor at the Wuwei campus of the Chinese Academy  of Sciences' Shanghai Institute of Applied Physics in Minqin county of  Wuwei city, Northwest China's Gansu province, Oct 24, 2025.  [Photo/Xinhua]

China's thorium molten salt reactor has become the first in the world  to transmute thorium fuel into uranium fuel for nuclear fission.

Key physical parameter data of protactinium-233 confirms the  successful establishment of a nuclide conversion chain from thorium-232  to uranium-233 within the reactor. The milestone preliminarily verifies  the technical feasibility of the thorium fuel cycle and further  consolidates China's leading position in molten salt reactor research.

The 2-megawatt thermal liquid-fueled thorium molten salt reactor, led  by the Shanghai Institute of Applied Physics of the Chinese Academy of  Sciences, is situated in the Hongshagang industrial cluster in Minqin  county, administered by Wuwei city, Gansu province.

"Nuclear energy, characterized by high energy density, near-zero  carbon emissions and independence from seasonal variations, is a safe,  clean, efficient and low-carbon energy source. It plays a crucial role  in safeguarding energy security and advancing large-scale  commercialization goals," said Cai Xiangzhou, deputy director of the  Shanghai Institute of Applied Physics.

Cai highlighted that China has witnessed consistent growth in newly  installed nuclear power capacity each year. However, the country faces  sustainability challenges due to its heavy reliance on imported uranium —  the most widely used nuclear fuel. The issue underscores the critical  importance of a stable nuclear fuel supply for sustainable development.

Dai Zhimin, director of the Shanghai Institute of Applied Physics,  said that thorium fuel is widely regarded as a promising alternative to  uranium, citing two key advantages: China's abundant thorium reserves  and its negative temperature coefficient of reactivity, which  effectively mitigates the risks of radioactive release. In addition,  thorium-fueled reactors generate spent fuel with reduced volume and  shorter radioactive half-lives, significantly simplifying waste  disposal.

"As a fourth-generation nuclear power reactor type, molten salt  reactors use high-temperature molten salt as a coolant. Endowed with  inherent safety features, water-free cooling, low-pressure operation and  high-temperature output, they are internationally recognized as the  most suitable reactor type for thorium resource utilization," Dai said.

He added that the technology facilitated deep integration with  industries such as solar energy, wind power, high-temperature molten  salt energy storage, high-temperature hydrogen production, and coal, oil  and gas chemical engineering.

In response to the national strategic demands for energy security and  sustainable development, the CAS launched a program in 2011 to enhance  core technological capabilities and develop a thorium-based molten salt  reactor system.

Construction of the reactor commenced in 2020, with equipment  installation completed in 2022. By June 2024, it reached full-power  operation at 650 C. In September, it obtained the world's first  experimental license for thorium loading in a molten salt reactor. Last  October, the first thorium loading was successfully completed,  establishing the world's only research platform dedicated to molten salt  reactors and thorium-uranium fuel cycle studies.

"The program brought together nearly 100 domestic research  institutions, universities and industrial companies. The collaborative  team overcame key challenges in reactor design, the development of  critical materials and equipment, reactor safety, and installation and  commissioning," Cai said.

Cai emphasized that the team had pioneered technologies for  controlling oxygen content in thorium fluoride and established a  preparation process for nuclear-grade thorium-based fuel salt.

"Over 90 percent of the reactor's components are domestically  produced, with 100 percent localization of key parts and a fully  independent supply chain. This achievement marks the initial  establishment of an industrial ecosystem for thorium molten salt reactor  technologies in China," he added.

Dai said: "The Shanghai Institute of Applied Physics will collaborate  with leading energy enterprises, including the State Power Investment  Corporation, to build a comprehensive industrial and supply chain  ecosystem for the thorium molten salt reactors.

"Our goal is to complete the construction and demonstration operation  of a 100-megawatt thermal prototype by 2035 and realize  commercial-scale application. This will accelerate technological  innovation and engineering transformation, ultimately providing China  with a safe, reliable and domestically controlled thorium-based energy  generation solution."

Contact the writers at limenghan@chinadaily.com.cn