What is Molten Salt Reactor?

A nuclear reactor design that uses molten fluoride or chloride salts as coolant, fuel carrier, or both — enabling operation at high temperatures and low pressures with inherent safety advantages.

Which deep tech sector does Molten Salt Reactor belong to?

Molten Salt Reactor is a key concept in the Small Modular Reactors sector.

Molten Salt Reactor — Deep Tech Glossary

Molten salt reactors (MSRs) are among the most promising advanced nuclear designs, offering a fundamentally different approach from conventional solid-fuel, water-cooled reactors. In an MSR, salts — typically fluorides of lithium, beryllium, or sodium — are heated to liquid form and circulated through the reactor core. The fuel can either be dissolved directly in the salt (fuel-salt MSRs) or contained in solid form with the salt acting only as coolant (clean-salt MSRs). Because molten salts operate at atmospheric pressure and have high boiling points, MSRs avoid the high-pressure containment requirements of water-cooled reactors.

Several companies are developing MSR technology. Kairos Power, backed by significant DOE support, is building its Hermes demonstration reactor in Tennessee using a fluoride salt coolant with TRISO pebble fuel. Terrestrial Energy in Canada is advancing its Integral Molten Salt Reactor (IMSR). TerraPower initially pursued MSR technology before pivoting to its sodium-cooled Natrium design. In China, the Shanghai Institute of Applied Physics has built a small experimental thorium MSR, making it one of the first MSR projects to reach operational status in decades.

The appeal of MSRs extends beyond safety. Their high operating temperatures (600-700+ degrees Celsius) enable efficient electricity generation and industrial process heat for hydrogen production, desalination, and chemical manufacturing. Challenges include developing salt-compatible structural materials that resist corrosion over decades, managing radioactive salt chemistry, and navigating regulatory frameworks designed primarily for solid-fuel water-cooled reactors. For deeper coverage, see DeepTechIntel's nuclear section.