Chinese scientists have successfully refuelled an experimental thorium-fueled molten salt reactor continuously without shutting it down. The Chinese reactor prototype reached full operational power in June 2024, and in October researchers reloaded fuel while the reactor remained online, a world-first.
The achievement was announced recently by Xu Hongjie, head of the scientific team responsible for the thorium reactor project, during a meeting of the Chinese Academy of Sciences (CAS). “We are now at the frontier of global nuclear innovation,” he said.
Xu and his team at the Shanghai Institute of Applied Physics (SINAP – Chinese Academy of Sciences) developed and advanced the technology based on declassified research from the USA. He explained that researchers in the US had been building and testing early molten salt reactor technology since the 1960s, but did not develop it further, choosing to focus on uranium fuelled pressurised water reactor technology. [CEN note: This technology was more conducive to the US’s production of Uranium isotopes for nuclear weapons.]
“The US left its research publicly available, waiting for the right successor. We were that successor,” he told the CAS meeting. “We mastered every technique in the literature – then pushed further.”
China has been quietly reviving this abandoned technology since 2011. Xu said construction of the experimental reactor in the Gobi Desert began in 2018. He noted that their team grew from initially several dozen people to more than 400.
The reactor design uses molten fluoride salts to dissolve the thorium fuel, functioning both as a coolant and as a carrier of fissile material. This allows the system to operate at high temperatures exceeding 700°C, but without the high pressures associated with traditional reactors. [CEN Note: The Chinese developed sytem has a built-in safety system that eliminates meltdowns of the type seen in the Fukishima and Chernobyl disasters]. The use of thorium-232, which must be converted into fissile uranium-233, enables a completely different nuclear fuel cycle with a lower risk of proliferation and significantly fewer long-lived radioactive waste products.
Thorium is not only more abundant than uranium – available in three to four times greater quantities globally – but also less suitable for weapons production. The reactor produces very low amounts of plutonium-239, the isotope commonly used in nuclear weapons, and the uranium-233 bred from thorium is more difficult to separate and utilise for military purposes. According to Chinese reports, the plutonium content of thorium reactor waste is “much lower” than in conventional nuclear systems.
The reactor also has passive safety features. In the event of overheating or power failure, the system uses a “frozen salt plug” at the bottom of the reactor vessel that melts automatically, allowing molten radioactive salt to drain into a secondary cooling chamber. This gravity-fed shutdown prevents meltdowns without requiring active control or external intervention.
China has already broken ground on a larger, 10 MWe demonstration Thorium reactor, located near Wuwei in Gansu Province, which will generate both electricity and hydrogen. This facility, slated for completion by 2030, is designed to produce 60 MW of thermal energy, contributing to China’s larger goal of building a renewable and low-carbon energy hub in the desert.
The thorium molten salt system is also being eyed for non-electrical applications. The high temperatures of the reactor make it ideal for thermochemical hydrogen production, potentially transforming the economics of green hydrogen. There are also early-stage concepts for thorium-powered ships, particularly container vessels. These could run for years without refuelling, significantly reducing maritime emissions.
- [Edited extract from source below].
Source: Nuclear Engineering International, April 22, 2025. https://www.neimagazine.com/…/china-refuels-thorium…/
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