The URENCO centrifuge consists of an ultra-light, thin-walled tube made from advanced materials, containing a cylindrical rotor that rotates at high velocity in a vacuum, on an almost frictionless bearing.
The gaseous UF6 is fed into the centrifuge, where it adopts a rotational motion. The centrifugal forces push the heavier U238 closer to the wall of the rotor than the lighter U235. The gas closer to the wall becomes depleted in U235, whereas the gas nearer the rotor axis is slightly enriched in U235. The centrifuge's electric motor produces heat at the base of the machine, causing a temperature profile along the length of the centrifuge, assisting the separation process.
The gaseous UF6 is fed through a pipe from the top of the centrifuge into the centre of the cylinder, where it takes up the rotational motion and also flows along the temperature gradient. The two streams of UF6, one enriched and one depleted in U235 are removed from the centrifuge by two pipes.
The enrichment level achieved by a single centrifuge is insufficient to obtain the desired concentration of U235. It is therefore necessary to connect a number of centrifuges together, both in series and in parallel. This arrangement of centrifuges is known as a cascade. Passing through the successive centrifuges of the cascade, the U235 is gradually enriched to the required assay, typically between 3% and 5% by weight.