Uranium conversion, explained
Uranium conversion turns yellowcake (U₃O₈) into uranium hexafluoride (UF₆) for enrichment. How the conversion process works and why capacity is scarce.
Uranium conversion is the step in the nuclear fuel cycle that turns yellowcake (U₃O₈) into uranium hexafluoride (UF₆), the chemical form required for enrichment. It sits between the traded commodity form of uranium and the enrichment stage. Conversion capacity is concentrated in a few facilities, which makes it one of the tighter points in the fuel supply chain.
How the uranium conversion process works
Enrichment is performed on uranium in gaseous form, and yellowcake is a solid powder. Conversion changes the material from one form to the other. The process purifies the uranium and combines it with fluorine to produce UF₆. UF₆ is solid at room temperature and becomes a gas at moderate heat, which is the property enrichment requires.
The output is UF₆ in sealed steel cylinders, ready to be fed into an enrichment plant. Conversion is priced separately from the uranium itself, as a service charged per kilogram of uranium converted.
The conversion process, step by step
Commercial conversion follows one of two routes, dry or wet, but both perform the same chemistry. In simplified form, the sequence has five steps.
- Receipt and sampling. Drums of U₃O₈ arrive from mills and are sampled to confirm uranium content and impurities.
- Purification. The concentrate is purified to remove impurities that would interfere with enrichment.
- Conversion to UO₂ and UF₄. The purified uranium is reduced to uranium dioxide, then reacted with hydrogen fluoride to form uranium tetrafluoride (UF₄).
- Fluorination to UF₆. The UF₄ is reacted with fluorine gas to produce UF₆.
- Filling cylinders. The UF₆ is collected and filled into steel cylinders for shipment to an enrichment plant.
A related service, sometimes also called conversion, works in the other direction. Depleted UF₆ left over from enrichment can be deconverted into a stable oxide for long-term storage.
How conversion is bought and priced
Utilities buy conversion as a separate service, alongside uranium, enrichment, and fuel fabrication. Like uranium, conversion is bought mostly under multi-year term contracts, with a smaller spot market. Price indicators for conversion are published separately from the uranium price, in U.S. dollars per kilogram of uranium.
The utility usually owns the uranium throughout. It delivers U₃O₈ to the converter's account, pays the conversion fee, and receives a matching quantity of uranium as UF₆ credited to its account for delivery to the enricher.
Why conversion capacity is scarce
Only a small number of commercial conversion facilities operate worldwide, and new capacity is slow and capital-intensive to build. Commercial conversion capacity is located in the United States, Canada, France, Russia, and China. The conversion facility in Metropolis, Illinois is the only operating conversion facility in the United States.
Because supply is concentrated in so few places, conversion has its own market and price. Periods of tight conversion capacity can raise the delivered cost of nuclear fuel even when uranium is available.
Why conversion facilities are the market's custody points
Conversion facilities also hold physical uranium and record changes in ownership. Institutions that own uranium typically hold it in a book account at a conversion facility. Ownership transfers between accounts by book transfer rather than by moving the material. Accredited conversion facilities are, as a result, the custody and settlement points of the physical uranium market.
Conversion and Uranium Digital
Uranium Digital's digital warehouse receipts are backed 1:1 by physical U₃O₈ held at an accredited U.S. conversion facility, and independently audited. Redemption settles by book transfer of U₃O₈ into the redeeming institution's account at the conversion facility, using the same custody infrastructure the market already relies on. See physical settlement, and the nuclear fuel cycle for the full path from ore to fuel.
FAQ
Uranium conversion is the step in the nuclear fuel cycle that turns yellowcake (U₃O₈) into uranium hexafluoride (UF₆), the form used for enrichment. The process purifies the uranium and combines it with fluorine to produce a compound that becomes a gas when heated. Conversion sits between the mined, traded commodity and the enrichment stage.
Only a small number of commercial conversion facilities operate worldwide, and new capacity is slow and expensive to build. When conversion capacity is tight, it can raise the delivered cost of nuclear fuel even when uranium itself is available. This is why conversion trades as its own market, separate from the uranium commodity.
The conversion facility in Metropolis, Illinois is the only operating uranium conversion facility in the United States. Other commercial conversion capacity is located in Canada, France, Russia, and China.
Conversion facilities are where physical uranium is held and where ownership is transferred. Institutions hold uranium in a book account at a conversion facility, and title moves between accounts by book transfer. On Uranium Digital, physical U₃O₈ backing digital warehouse receipts is held at ConverDyn and settled the same way.