From Thorium to Power: China Achieves Uranium-Breeding Milestone

Researchers at the Chinese Academy of Sciences have reached a pivotal energy independence milestone, successfully "breeding" nuclear fuel from thorium in an experimental reactor. The team at the Shanghai Institute of Applied Physics has confirmed their thorium-based molten salt reactor can convert abundant thorium into fissile uranium-233, creating a self-sustaining fuel cycle that could power China for centuries using its vast domestic thorium reserves.

In a breakthrough that could fundamentally reshape nuclear energy, Chinese scientists have demonstrated the world's first successful thorium-to-uranium fuel conversion within an operating reactor. The 2 megawatt liquid-fuelled thorium-based molten salt reactor (TMSR), located in China's Gobi Desert, has become the only operational reactor of its kind to achieve this technological feat, marking what researchers call "a major leap forward" for clean, sustainable nuclear power.

According to Science and Technology Daily, which published China's first official confirmation of the success on Saturday, the experiment provides crucial experimental data on thorium operations from inside a molten salt reactor—something never before accomplished globally. The achievement validates the technical feasibility of using China's enormous thorium resources in advanced reactor systems that could provide virtually limitless clean energy.

Li Qingnuan, Communist Party secretary and deputy director at the Shanghai Institute of Applied Physics, confirmed the reactor's operational status to the newspaper. "Since achieving first criticality on October 11, 2023, the thorium molten salt reactor has been steadily generating heat through nuclear fission," she stated. This continuous operation has allowed researchers to gather invaluable data on the complex nuclear transformations occurring within the reactor core.

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The revolutionary process at the heart of this achievement is called in-core thorium-to-uranium conversion. It transforms naturally occurring thorium-232—a weakly radioactive element that cannot sustain a chain reaction on its own—into uranium-233, a powerful fissile isotope that releases tremendous energy. This transformation occurs through a precise sequence where thorium-232 absorbs a neutron to become thorium-233, which decays into protactinium-233 and then further decays into the final uranium-233 product.

What makes this technology truly transformative is China's abundant thorium reserves. "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," reported Science and Technology Daily. This domestic abundance means China could achieve genuine energy independence, free from the geopolitical constraints and supply chain vulnerabilities associated with traditional uranium fuel.

The TMSR's design represents a radical departure from conventional nuclear technology. Unlike traditional pressurized water reactors that use solid fuel rods and require shutdowns for refueling, the TMSR uses a homogeneous mixture of fissile material dissolved in molten fluoride salts that serves as both fuel and coolant. This liquid fuel circulates continuously, enabling what researchers call a "burn while breeding" cycle where thorium continuously converts to uranium-233 while simultaneously releasing energy through fission.

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"This design not only dramatically improves fuel utilization but also significantly reduces the volume of long-lived radioactive waste," Li explained. "It's one of the key advantages that sets thorium molten salt reactors apart." The system also operates at atmospheric pressure, eliminating the risk of high-pressure explosions that concern conventional reactor designs.

Another revolutionary advantage is the reactor's independence from water cooling. While traditional nuclear plants must be built near coastlines or large water sources, the TMSR uses high-temperature molten salts that efficiently transfer heat without water. This opens the door to deploying nuclear power in arid inland regions of China and even on mobile platforms like large ships—expanding nuclear energy's potential reach dramatically.

The journey to this breakthrough began in 2011 when the Chinese Academy of Sciences launched the TMSR program as a strategic priority. After nearly 15 years of research and development led by Xu Hongjie, former director of the Shanghai institute, the team overcame formidable challenges in materials science, reactor design, and nuclear chemistry. Their efforts culminated in the reactor achieving first criticality in October 2023, followed by full power operation in June 2024, and finally the historic thorium-loading experiment this year.

Safety remains paramount in the design. The system operates underground with full radiation shielding, and its chemically stable molten salts effectively trap radioactive materials. In the unlikely event of a leak, the molten salt would flow into a passive safety drain tank, solidifying as it cools and containing any potential release.

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With a complete industrial ecosystem for TMSR technology now taking shape in China—including nearly 100 research institutions and 100 percent domestically produced core components—the country is building a 100MW demonstration reactor in the Gobi Desert with the goal of proving commercial viability by approximately 2035. This successful thorium-breeding experiment represents not just a scientific achievement but a potential pathway to sustainable energy independence for centuries to come.