• Thorium is more abundant in nature than uranium.
• It is fertile rather than fissile, and can only be used as a fuel in conjunction with a fissile material such as recycled plutonium.
• Thorium fuels can breed fissile uranium-233 to be used in various kinds of nuclear reactors.
• Molten salt reactors are well suited to thorium fuel, as normal fuel fabrication is avoided.

The use of thorium as a new primary energy source has been a tantalizing prospect for many years. Extracting its latent energy value in a cost-effective manner remains a challenge, and will require considerable R&D investment.