HEU to LEU: Step by Step

See how the Megatons to Megawatts program recycles nuclear warheads into fuel for nuclear power plants.

Dismantlement

Warhead dismantlement

The conversion of highly enriched uranium (HEU) from Russian nuclear weapons into low enriched uranium (LEU) for use in fabricating fuel for commercial nuclear power reactors took place at several nuclear installations in Russia and began with the removal of the warheads and their HEU metal components from strategic and tactical nuclear missiles.

Downblending

Downblending of HEU to LEU

Oxidation

At the Siberian Chemical Enterprise (SChE) (formerly Tomsk-7) in Seversk and the Mayak Production Association (MPA) near Ozersk, the HEU warhead components were machined into metal shavings. The shavings were then heated and converted to an HEU oxide and any contaminants were chemically removed.

Fluorination

At SChE and the Electrochemical Plant (ECP) near Krasnoyarsk, the HEU oxide was converted to highly enriched uranium hexafluoride (UF6), a compound that becomes a gas when heated.

Dilution

At SChE, ECP and the Urals Electrochemical Integrated Plant (UEIP) near Ekaterinburg, the highly enriched UF6 was introduced into a gaseous process stream. There, it was mixed with other material and was diluted to less than 5 percent concentration of the fissionable uranium-235 isotope, a level too low to be of any military value but ideal for producing electric power.

Transfer to Cylinders

At the three dilution facilities, the now low enriched uranium (LEU) was checked to ensure the product meets commercial specifications and was then transferred to 2.5-ton steel cylinders. 

Shipment to St. Petersburg

Cylinders loaded for shipment

The LEU was enclosed in shipping containers and sent to a collection point in St. Petersburg. Centrus took possession of the containers in St. Petersburg, and they were delivered to Centrus' facilities in the United States.

Arrival at Centrus Facility

USEC enrichment plant

At Centrus' facilities (originally the Portsmouth Gaseous Diffusion Plant but later the Paducah Gaseous Diffusion Plant), the LEU was tested again to ensure that it meets appropriate commercial and customer specifications. If necessary, the enrichment level of the uranium was further adjusted to meet utility customers’ needs. 

Shipment to Fabricators

Fuel fabricator

Centrus shiped the warhead-derived LEU to fabricators, who converted it into uranium oxide pellets and fabricated them into fuel assemblies. The assemblies were then delivered to Centrus' utility customers as a source of fuel for their nuclear reactors.

HEU Transparency Program

To provide confidence that the LEU from Russia was actually derived from warhead material, the U.S. Department of Energy and the National Nuclear Security Administration administered the HEU Transparency Program. Through this program, the NNSA monitored several steps in the process described above to provide confidence that the nonproliferation objectives were met.

Nuclear Fuel Cycle

Nuclear power is a vital part of the world's energy mix. Find out how the uranium fuel that powers the world's nuclear reactors is mined and processed in several important steps that make up the nuclear fuel cycle.

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