Uranium Enrichment

Abstract

Only gas graphite reactors and heavy water reactors can operate with natural uranium (${\sim }0.7\%$ U-235). However, the burnup of their fuel is limited. Present light water reactors operating with a fuel burnup of about 55–60 $\text{ GW}_\mathrm{ th}/\text{ t}$ need their uranium fuel enriched to 4–5% U-235 content. Uranium enrichment is performed almost exclusively by the gaseous diffusion and gas centrifuge process. The gaseous diffusion enrichment plants in the USA and France provide about 42% of the worldwide enrichment capacity. Gaseous diffusion plants will phase out in the near future as more economic gas centrifuge plants will be built which provide already about 58% of the world wide enrichment capacity. The separative work unit (SWU) which is a measure of the amount of energy necessary to produce a certain unit (amount) of enriched uranium is by an order of magnitude lower (in e.g. SWU/kg U) for centrifuge enrichment than for gaseous diffusion enrichment. Laser isotope separation, chemical isotope separation and plasma isotope separation were scientifically studied. Only one laser isotope separation (SILEX) plant is being built in the USA.