Nuclear Glossary

U3O8 (Yellowcake)
U3O8 or Yellowcake is milled and treated uranium ore. It is unrefined and contains natural uranium. Through conversion, it is treated to become UF6, Uranium Hexafluoride.

Conversion
Conversion is a service to convert the U3O8 into UF6. It is essential that the uranium be in the UF6 form for further refinement.

UF6
Uranium Hexafluoride is a crystalline solid that easily sublimes into a gas. Through SWU, it becomes EUP.

Tails
Uranium tails are the leftovers from the UF6 refinement process, and are unusable for fission, and thus a waste product. Tails contain mostly U238, however, as the refinement process is not 100% efficient, a small amount of U235 remain in the tails.

Optimum Tails
Optimum tails for Uranium represents the most cost efficient way of refining Uranium, with the smallest possible amount of U235 in the waste stream.
 
SWU
SWU (Seperative Work Units) is a unit of measurement that refers the amount of energy necessary to enrich uranium by 1% by volume. It is the process used to convert UF6 into EUP. It is either done in a centrifuge or through gaseous diffusion. Centrifuge uses less energy and is more effective.

EUP
Enriched Uranium Product is the final stage of the enrichment process. It is approximately 4-5% U235 by volume, significantly up from the 0.7% that occurs naturally. The EUP is suitable for use in reactors after it has been processed into pellets or fuel rods.