The Fuel Cycle: From Mine to Reactor

The fuel in a US reactor has been on a long industrial journey, and each stage of it appears as an amber square on this map's fuel-cycle layer.

It begins as uranium ore — or more often today, as uranium dissolved out of underground sandstone by in-situ recovery (ISR), the technique used at the Wyoming, Texas, and Nebraska sites on the map: oxygenated water circulates through the ore body via wells, leaches out the uranium, and surfaces it with no open pit at all. Conventional milling (the White Mesa mill in Utah is the country's last) crushes mined ore and chemically extracts the same product: yellowcake (U₃O₈), a coarse yellow-to-brown powder that is barely radioactive — you could stand beside a drum of it safely — but is the raw material of everything that follows.

Yellowcake can't be enriched directly; enrichment needs a gas. Conversion turns U₃O₈ into uranium hexafluoride (UF₆), a compound with the convenient property of becoming gaseous just above room temperature. One facility in the United States does this — Honeywell's Metropolis Works in Illinois, a single amber square carrying an entire stage of the national fuel cycle.

Enrichment is the technological heart. Natural uranium's 0.7% U-235 must become 3–5% for standard reactor fuel, and the working method is the gas centrifuge: UF₆ spins in a tall rotor at tens of thousands of rpm, the marginally heavier U-238 molecules drift outward, and cascades of thousands of centrifuges in series multiply a tiny per-stage separation into reactor-grade product. Enrichment effort has its own unit — the separative work unit (SWU) — and its own strategic geography: the only commercial-scale enrichment plant in the US is Urenco's facility in Eunice, New Mexico, with new American capacity (Centrus in Piketon, Ohio; Orano's planned Oak Ridge plant; laser enrichment at Wilmington, NC) racing to grow, for reasons just below.

Fabrication turns enriched UF₆ into fuel: reconverted to uranium dioxide powder, pressed and sintered into ceramic pellets, loaded into zirconium-alloy tubes, and assembled into the precision-engineered fuel bundles described in the plant-anatomy page. The fabrication plants in Columbia SC, Richland WA, and Wilmington NC supply the operating fleet; new facilities like TRISO-X in Oak Ridge exist for the advanced-reactor fuels described next page.

Now the uncomfortable geography. The United States operates the world's largest reactor fleet and mines about 1% of the uranium it consumes. The rest is imported — Canada, Kazakhstan, and Australia are the major suppliers, with Kazakhstan alone producing roughly 40% of the world's uranium. Russia, long a major supplier of enrichment services in particular, was banned by US law in 2024 (with wind-down waivers), which converted a slow strategic worry into an immediate commercial one: enrichment capacity outside Russia is now the bottleneck the Western industry is investing to clear. The fuel-cycle layer's import-sources panel summarizes this dependence.

One more term you'll meet constantly in the advanced-reactor world: HALEU — high-assay low-enriched uranium, enriched to between 5% and 20%. Many next-generation designs (TerraPower's Natrium, Oklo's Aurora, X-energy's TRISO-fueled Xe-100) need it, almost no Western capacity existed to make it until Centrus began first US HALEU production in Piketon in 2023, and scaling that supply is one of the genuine schedule risks for the entire advanced-reactor pipeline. When you read that a new reactor's fuel is "not yet available at commercial scale," HALEU is usually what's meant.