Thoriumbased

Thoriumbased refers to nuclear fuel cycles and reactor concepts that use thorium, primarily thorium-232, as a fertile material to breed fissile uranium-233 for sustained fission.

In a thorium-based cycle, Th-232 absorbs a neutron to become Th-233, which beta decays to protactinium-233 and then to uranium-233, the fissile species. U-233 then can be fissioned to release energy. Starting the cycle requires a source of neutrons and a reactor design capable of handling the chemical and radiological properties of thorium fuel.

Prominent designs include molten salt reactors such as liquid fluoride thorium reactors (LFTRs) that dissolve thorium fluoride in molten salts, enabling online reprocessing and operation at high temperature with improved safety margins. Other approaches include using thorium in existing light-water or heavy-water reactors as an admixture and in Canada’s heavy-water reactor programs.

Advantages include the relative abundance of thorium, especially in a world with limited uranium; potential for reduced long-lived transuranic waste; and higher fuel utilization in some designs. Limitations include U-233's potential for weapons use, technical challenges in achieving sustained breeding, and the need for reprocessing to separate fissile U-233, which raises proliferation concerns.

Status and challenges: Thoriumbased systems have not progressed to commercial deployment on a wide scale; pilot programs exist in several countries, and research organizations continue to explore reactor concepts, materials, and fuel-cycle chemistry. Regulatory and economic hurdles, material compatibility with high-temperature salts, and the requirement for robust fuel reprocessing infrastructure have slowed commercialization.

Thorium reserves are more abundant than uranium, with large deposits in India, Australia, and Africa; interest in thoriumbased energy has persisted since the mid-20th century as a potential solution for energy security and waste management.