Thorium Reactors: A Safer Alternative to Uranium fueled Reactors without the Proliferation risk
Tom Jigme Wheat
Team working on project reportedly achieves milestone by completing fuel reloading while experimental molten salt reactor was running
Chinese scientists have achieved a milestone in clean energy technology by successfully adding fresh fuel to an operational thorium molten salt reactor, according to state media reports.
It marks the first long-term, stable operation of the technology, putting China at the forefront of a global race to harness thorium – considered a safer and more abundant alternative to uranium – for nuclear power.
The development was announced by the project’s chief scientist, Xu Hongjie, during a closed-door meeting at the Chinese Academy of Sciences on April 8, the official Guangming Daily reported on Friday.
The experimental reactor, located in the Gobi Desert in China’s west, uses molten salt as the fuel carrier and coolant, and thorium – a radioactive element abundant in the Earth’s crust – as the fuel source. The reactor is reportedly designed to sustainably generate 2 megawatts of thermal power.
During the April 8 meeting, Xu said China “now leads the global frontier”, according to Guangming Daily.
He made reference to Aesop’s fable The Tortoise and the Hare to compare the race between China and the United States to develop the technology.
“Rabbits sometimes make mistakes or grow lazy. That’s when the tortoise seizes its chance,” Xu told the meeting, referring to the US abandoning its molten salt reactor research in the 1970s after initial experiments.
American scientists pioneered molten salt reactor technology – including building a small test reactor in the 1960s – but the project was shelved in favour of uranium-based systems.
“The US left its research publicly available, waiting for the right successor,” Xu was quoted as saying. “We were that successor.”
His team at the CAS Shanghai Institute of Applied Physics spent years dissecting declassified American documents, replicating experiments, and innovating beyond them. “We mastered every technique in the literature – then pushed further,” he said.
China’s thorium molten salt reactor project began with theoretical research in the 1970s, and in 2009 the CAS leadership tasked Xu with making the next-generation nuclear energy technology a reality, according to state media reports.
The project team expanded from dozens of members to more than 400 researchers within two years.
“We learned by doing, and did by learning,” Xu said. The challenges were immense – designing new materials, troubleshooting for extreme temperatures, and dealing with engineering components that had never been built before.
After construction of the experimental reactor started in 2018, most of the scientists involved in the project abandoned their holidays – they worked day and night, and some stayed on site for more than 300 days in a year.
By October 2023 it was built and achieved criticality – a sustained nuclear chain reaction. And by June 2024 it had reached full-power operation.
Four months later the process of thorium fuel reloading was completed while the reactor was running – making it the only operational thorium reactor in the world.
“We chose the hardest path, but the right one,” Xu was quoted as saying, referring to the drive for a real-world application rather than a purely academic pursuit.
He also noted the significance of the date when the reactor achieved full power, telling the meeting that “57 years ago to the day – June 17 – China detonated its first hydrogen bomb”.
Now it wants to replicate that disruptive impact on the energy sector.
A much bigger thorium molten salt reactor is already being built in China and is slated to achieve criticality by 2030. That research reactor is designed to produce 10 megawatts of electricity.
Meanwhile, US efforts to revive the development of a molten salt reactor remain on paper, despite bipartisan congressional support and Department of Energy initiatives.
According to Xu, abandoning the project was seen as “a forgivable mistake” in the US, in part because the technology was not ready.
But “in the nuclear game, there are no quick wins”, he was quoted as saying. “You need to have strategic stamina, focusing on doing just one thing for 20, 30 years.”