China has world’s first thorium reactor in landmark for clean nuclear energy

China has activated the world’s only operational thorium molten salt reactor, marking a global breakthrough in clean nuclear energy using declassified United States research.

Chinese scientists reloaded fuel into the working reactor in the Gobi Desert without halting operations, a feat revealed during a closed-door meeting at the Chinese Academy of Sciences (CAS) on April 8, according to Guangming Daily.

The 2-megawatt experimental unit, designed to run on thorium, uses molten salt as a coolant and fuel carrier. Project chief scientist Xu Hongjie confirmed that the reactor had reached critical milestones, including full-power operation in June 2024 and successful in-operation fuel reloading four months later.

“We now lead the global frontier,” Xu said at the meeting. “Rabbits sometimes make mistakes or grow lazy. That’s when the tortoise seizes its chance.”

Thorium is seen by experts as a safer, more abundant alternative to uranium. It produces less long-lived radioactive waste and carries a lower risk of weaponisation.

Combined with molten salt reactor design—first tested by US scientists in the 1960s—this technology operates at atmospheric pressure and is engineered to self-limit overheating.

The Chinese team relied heavily on declassified American research to develop their system. “The US left its research publicly available, waiting for the right successor,” Xu said. “We were that successor.”

Researchers at the CAS Shanghai Institute of Applied Physics built upon historical data, recreated experiments, and advanced them. Construction began in 2018, and the team has grown to over 400 members, many of whom worked through holidays to keep the project on schedule.

The breakthrough aligns with China's ambition to diversify its energy portfolio. A larger 10-megawatt thorium reactor is under construction and expected to reach criticality by 2030. China has also announced plans for thorium-powered cargo ships, aiming to reduce emissions in global maritime transport.

Xu noted the symbolic timing of the development, highlighting that June 17 marks the anniversary of China’s first hydrogen bomb test. “We chose the hardest path, but the right one,” he said.