China Achieves World’s First Thorium-Uranium Fuel Conversion in Molten Salt Reactor

The Shanghai Institute of Applied Physics, Chinese Academy of Sciences, announced that the Thorium Molten Salt Reactor (TMSR-LF1) has successfully achieved the first-ever thorium–uranium nuclear fuel conversion.

• This milestone makes China the first country in the world to obtain experimental data after introducing thorium into a molten salt reactor, and the only operational reactor globally that has successfully incorporated thorium fuel.

About the TMSR-LF1 Reactor

• Type: Thorium-powered Molten Salt Reactor (MSR).
• Fuel: Uranium enriched to less than 20% uranium-235.
• Thorium inventory: ~50 kg.
• Conversion ratio: ~0.1 (ratio of new fissile material bred to fissile material consumed).
• Coolant: Lithium-beryllium fluoride (FLiBe) with 99.95% Li-7, serving as the fertile blanket.
• Fuel compound: Uranium tetrafluoride (UF₄).
• Significant milestone: In October 2024, the first-ever thorium addition to a molten salt reactor was completed, paving the way for this achievement.

About Molten Salt Reactors (MSRs)

• Generation: Part of the fourth-generation advanced nuclear reactor systems.
• Coolant: Use molten fluoride salts instead of water.
• Pressure: Operate at atmospheric pressure, enhancing safety.
• Safety Features:
  • Inherent cooling without water.
  • Low-pressure operation, reducing explosion risks.
  • High-temperature output, improving thermal efficiency.
• Flexibility: Can operate with epithermal or fast neutron spectrums and various fuels, including thorium and uranium.

Significance of the Achievement

• Marks a breakthrough in thorium fuel cycle research, an area long regarded as a potential path to sustainable nuclear energy.
• Establishes China’s unique molten salt reactor and thorium-uranium fuel cycle platform — a first of its kind globally.
• Offers prospects for safer, cleaner, and more efficient nuclear power, with reduced long-term radioactive waste.

India’s Thorium Programme

• India has one of the world’s largest thorium reserves, mainly found in monazite sands along the southern coasts.
• The Department of Atomic Energy (DAE) has developed a three-stage nuclear power programme to utilise thorium as a long-term, sustainable energy source:
  1. Stage 1 – Pressurised Heavy Water Reactors (PHWRs):
     • Use natural uranium to produce electricity and plutonium as a by-product.
  2. Stage 2 – Fast Breeder Reactors (FBRs):
     • Use plutonium from Stage 1 to breed uranium-233 and more plutonium.
  3. Stage 3 – Thorium Reactors:
     • Use thorium (Th-232) to breed uranium-233 (U-233), enabling large-scale thorium utilisation.
• Goal: Achieve energy independence by using thorium, which is abundant, safe, and nearly inexhaustible.

About Thorium

• Element symbol: Th
• Atomic number: 90
• Naturally occurring radioactive metal, produced by radioactive decay of uranium.
• Found in minerals such as monazite, thorite, and thorianite.
• Offers high energy potential and lower nuclear waste generation compared to uranium.

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