Editing Enriched uranium (section)

===Centrifuge techniques===

====Gas centrifuge====
{{Main|Gas centrifuge}}

[[File:Gas centrifuge cascade.jpg|thumb|A cascade of gas centrifuges at a U.S. enrichment plant]]
The gas centrifuge process uses a large number of rotating cylinders in series and parallel formations. Each cylinder's rotation creates a strong [[centripetal force]] so that the heavier gas molecules containing <sup>238</sup>U move tangentially toward the outside of the cylinder and the lighter gas molecules rich in <sup>235</sup>U collect closer to the center. It requires much less energy to achieve the same separation than the older gaseous diffusion process, which it has largely replaced and so is the current method of choice and is termed second generation. It has a separation factor per stage of 1.3 relative to gaseous diffusion of 1.005,<ref name="Lodge"/> which translates to about one-fiftieth of the energy requirements. Gas centrifuge techniques produce close to 100% of the world's enriched uranium. The cost per separative work unit is approximately 100 dollars per [[Separative Work Units]] (SWU), making it about 40% cheaper than standard gaseous diffusion techniques.<ref name=Weinberger2012>{{cite journal |last=Weinberger |first=Sharon |title=US grants licence for uranium laser enrichment |journal=Nature |date=28 September 2012 |pages=nature.2012.11502 |doi=10.1038/nature.2012.11502 |s2cid=100862135 |doi-access=free }}</ref>

====Zippe centrifuge====
{{main|Zippe-type centrifuge}}
[[File:Zippe-type gas centrifuge.svg|thumb|upright|Diagram of the principles of a Zippe-type gas centrifuge with U-238 represented in dark blue and U-235 represented in light blue]]

The Zippe-type centrifuge is an improvement on the standard gas centrifuge, the primary difference being the use of heat. The bottom of the rotating cylinder is heated, producing convection currents that move the <sup>235</sup>U up the cylinder, where it can be collected by scoops. This improved centrifuge design is used commercially by [[Urenco Group|Urenco]] to produce nuclear fuel and was used by Pakistan in its nuclear weapons program.