Sodium-cooled fast reactor

A sodium-cooled fast reactor (SFR) is a fast neutron reactor cooled by liquid sodium.

The initials SFR in particular refer to two Generation IV reactor proposals, one based on existing liquid metal cooled reactor (LMFR) technology using mixed oxide fuel (MOX), and one based on the metal-fueled integral fast reactor.

Currently China, Russia and India have operational sodium-cooled fast reactors (see the list of reactors).

In 2020, Natrium received an $80M grant from the US Department of Energy for development of its SFR. The program plans to use High-Assay, Low Enriched Uranium fuel containing 5-20% uranium. The reactor was expected to be sited underground and have gravity-inserted control rods. Because it operates at atmospheric pressure, a large containment shield is not necessary. Because of its large heat storage capacity, it was expected to be able to produce surge power of 500 MWe for 5+ hours, beyond its continuous power of 345 MWe.

In the United States, TerraPower (using its Traveling Wave technology) is building its own reactor along with molten salt energy storage in partnership with GEHitachi's PRISM integral fast reactor design, under the Natrium appellation in Kemmerer, Wyoming.

Non-nuclear construction began in 2024, while the work on the nuclear island is expected to begin in 2026. The NRC issued the construction permit for Kemmerer Unit 1 on March 4, 2026.

In 2023, ARC Clean Technology Canada signed a memorandum of understanding with the Government of Alberta according to which Invest Alberta entity will support ARC's ARC-100 sodium-cooled 100 MWe reactor (based on Experimental Breeder Reactor II). ARC said that ARC-100 could become operational in 2029. ARC-100 project is a pool type reactor.

The nuclear fuel cycle employs a full actinide recycle with two major options: One is an intermediate-size (150–600 MWe) sodium-cooled reactor with uranium-plutonium-minor-actinide-zirconium metal alloy fuel, supported by a fuel cycle based on pyrometallurgical reprocessing in facilities integrated with the reactor. The second is a medium to large (500–1,500 MWe) sodium-cooled reactor with mixed uranium-plutonium oxide fuel, supported by a fuel cycle based upon advanced aqueous processing at a central location serving multiple reactors. The outlet temperature is approximately 510–550 degrees C for both.