Depleted uranium
Depleted uranium is the byproduct of enrichment, with less uranium-235 than natural uranium. What it is, how radioactive it is, and how it is used and stored.
Depleted uranium is uranium that contains a lower concentration of the fissile isotope uranium-235 than natural uranium. It is the byproduct of enrichment. When uranium is separated into an enriched stream and a depleted stream, the depleted stream, known as the tails, is left with typically 0.2 to 0.3 percent uranium-235, compared with about 0.7 percent in nature.
How depleted uranium is produced
Enrichment concentrates uranium-235 into a smaller quantity of product, so most of the uranium fed into an enrichment plant leaves as tails. Producing one kilogram of low-enriched uranium leaves roughly seven kilograms of depleted uranium. The tails leave the plant as depleted uranium hexafluoride (UF₆), which is stored in steel cylinders or deconverted into a more stable uranium oxide for long-term storage.
How radioactive depleted uranium is
Depleted uranium is weakly radioactive, about 60 percent as radioactive as natural uranium, because much of the uranium-235 and uranium-234 has been removed. It emits mainly alpha particles, which do not penetrate skin. The main health concern is inhaling or ingesting it, and like other heavy metals it is chemically toxic.
Uses of depleted uranium
Depleted uranium is very dense, about 1.7 times as dense as lead. That density makes it useful for radiation shielding, counterweights in aircraft, and military armor and armor-piercing munitions.
Depleted uranium and the uranium market
Depleted uranium sits outside the traded uranium commodity, which is yellowcake (U₃O₈) at natural enrichment. It is relevant to the market through the tradeoff between uranium feed and SWU. Enriching to a lower tails assay recovers more uranium-235 from each pound of feed but uses more enrichment work. When enrichment capacity is cheap relative to uranium, stored tails can also be re-enriched, which adds to uranium supply.
FAQ
Depleted uranium is uranium with less uranium-235 than natural uranium, typically 0.2 to 0.3 percent compared with about 0.7 percent. It is the byproduct, or tails, of the enrichment process. It is very dense and weakly radioactive.
Depleted uranium is about 60 percent as radioactive as natural uranium. It emits mainly alpha particles, which are stopped by skin or a sheet of paper, so external exposure is low. The main risks come from inhaling or ingesting it, and from its chemical toxicity as a heavy metal.
Depleted uranium is used where high density is valuable, including radiation shielding, aircraft counterweights, and military armor and munitions. Stored tails can also be re-enriched to recover more uranium-235 when enrichment capacity is cheap relative to uranium.