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1. Heating uranium hexafluoride (UF6) to turn it into a gas
UF6 is delivered to our enrichment facilities by approved suppliers in international standardised transport containers.
UF6 is solid at ambient temperature. At our enrichment facilities, we connect the transport container holding UF6 to the plant feed system. It is then heated in order to vaporise the UF6 and turn it into gas at sub atmospheric pressure.
2. Spinning UF6 in high speed centrifuges to enrich it
We feed the UF6 gas into a centrifuge casing containing a cylindrical rotor which spins at high speed, separating uranium’s two isotopes. The heavier isotope uranium238 (U238) is forced closer to the wall of the rotor than the lighter uranium235 (U235). As a result, the UF6 gas closer to the wall is depleted in U235 and the UF6 gas nearer the rotor axis is slightly enriched in U235. We repeat the process over and over again in a series of centrifuges, known as cascades, until we achieve the desired levels of U235 enrichment to meet our customers’ specifications, typically between 3% and 5%.
3. Compressing and cooling the enriched uranium
The enriched uranium is fed from the centrifuge cascades into a compressor and then into a cooling box containing a cylinder. As it cools, the UF6 vapour solidifies in cylinders. We homogenise the UF6 in the cylinders and check the quality of a sample before delivery to customers. We weigh all cylinders to comply with the accounting and tracking requirements of the European Atomic Energy Community, United States Nuclear Regulatory Commission and the International Atomic Energy Agency.
4. Storing and converting depleted uranium
The UF6 gas closer to the wall in the centrifuge is partially depleted in U235. This by-product is known as tails. We collect and cool tails in a cooling box containing a cylinder, weighing it to ensure all material can be accounted for. Tails still contain a low concentration of U235 and can be re-enriched if economically viable.
We store tails at our enrichment facilities in internationally approved containers pending deconversion to a chemically stable form, uranium oxide (U3O8), for long term storage for future enrichment or final disposal. Once operational, our Tails Management Facility will be responsible for deconversion and will convert UF6 to U3O8. This process additionally creates hydrofluoric acid, a valuable chemical used globally by industry.
Find out more about our Tails Management Facility here.