Chinese research institute confirms success of fission-based innovation that is poised to reshape clean, sustainable nuclear power
The achievement makes the 2 megawatt liquid-fuelled thorium-based molten salt reactor (TMSR) the only operating example of the technology in the world to have successfully loaded and used thorium fuel.
According to the academy, the experiment has provided initial proof of the technical feasibility of using thorium resources in molten salt reactor systems and represents a major leap forward for the technology.
It is the first time in the world that scientists have been able to acquire experimental data on thorium operations from inside a molten salt reactor, according to a report by Science and Technology Daily.
The article, published on Saturday, was China’s first official confirmation of its success in the development of TMSR technology, an innovation that is poised to reshape the future of clean sustainable nuclear energy.
Li Qingnuan, Communist Party secretary and deputy director at the Shanghai Institute of Applied Physics, told the newspaper that “since achieving first criticality on October 11, 2023, the thorium molten salt reactor has been steadily generating heat through nuclear fission”.
Thorium is much more abundant and accessible than uranium and has enormous energy potential. One mine tailings site in Inner Mongolia is estimated to hold enough of the element to power China entirely for more than 1,000 years.
At the heart of the breakthrough is a process known as in-core thorium-to-uranium conversion that transforms naturally occurring thorium-232 into uranium-233 – a fissile isotope capable of sustaining nuclear chain reactions.
This transformation occurs through a precise sequence of nuclear reactions. The thorium-232 absorbs a neutron to become thorium-233, which decays into protactinium-233 and then further decays into the final product – a powerful nuclear fuel.
Critically, the entire process takes place inside the reactor core, eliminating the need for external fuel fabrication.
Thorium is dissolved in a fluoride salt into a high-temperature molten mixture which serves as both fuel and coolant. Neutrons from a small initial charge of fissile material, such as enriched uranium-235 or plutonium-239, initiate the chain reaction.
Throughout the operation, thorium-232 continuously captures neutrons and transforms into uranium-233, which then releases energy through nuclear fission to create a self-sustaining “burn while breeding” cycle – one of the technology’s defining advantages.
Unlike conventional pressurised water reactors, which must be shut down periodically to open the pressure vessel and replace solid fuel rods, the TMSR’s liquid fuel – a homogeneous mixture of fissile material dissolved in molten salt circulates continuously, allowing for on-the-fly refuelling without interrupting operations.
“This design not only dramatically improves fuel utilisation but also significantly reduces the volume of long-lived radioactive waste,” Li said. “It’s one of the key advantages that sets thorium molten salt reactors apart.”
Another advantage of the TMSR is that it requires no water at all, in sharp contrast to conventional nuclear power plants that are usually built near coastlines because of their massive cooling needs.
The constraint has limited deployment of nuclear reactors in arid or inland regions but is no impediment to a TMSR system which uses high-temperature molten fluoride salts instead of water as both the fuel carrier and coolant.
Because the salts efficiently transfer heat at atmospheric pressure and extreme temperatures, the technology is opening the door to safe, efficient nuclear power plants deep inland – and even on mobile platforms such as large ships, according to the report.
The Chinese Academy of Sciences launched the TMSR nuclear energy system in 2011 as a strategic priority research programme aimed at addressing national goals in sustainable energy and carbon reduction.
