Cycle Front End

From the extraction of uranium to the fuel fabrication

The front-end of the nuclear cycle is the name given to the various stages ranging from the extraction of uranium ore in mines to the introduction of fuel assemblies in reactors.

The content in uranium of uranium ores is low and generally does not exceed a few percent. Mines are often located far from industrial sites. To avoid unnecessary transports of large tonnages over long distances, an initial concentration of uranium is carried out in close proximity to mining sites.

After a treatment which varies from one site to another, uranium is concentrated into a bright yellow powder, called “yellowcake”. The yellow cake contains about 750 kg of uranium per ton.

After transport, the next step is purification. Although already, concentrated the “cake” should be refined in order for uranium to get rid of impurities, for the preparation of the fuel.

Natural uranium contains only 0.7 % of uranium-235, the fissile iisotope that undergoes fission and produces energy in reactors.

For most existing reactors, natural uranium is not convenient and should be enriched in isotope 235. The industrial processes of isotope separation requires uranium to be in the form of uranium hexafluoride UF6, a fluorine gaseous compound. This uranium compound has the property of being able to pass easily from solid to liquid and gaseous states. Below 65 ° C it is liquid which facilitates the transport, above 65 ° C, it becomes gaseous and ready for enrichment. These operations of refining and conversion take place in France on the sites of Malvési, then Pierrelatte.

The final operation of isotope separation, by far the most complex, costly and strategic, is described elsewhere.

In 2000 the annual production in France was of 17,725 tons of raw uranium and 2,422 tons of enriched uranium (it has not varied much since). This would allow supplying fuel for 100 reactors of 1,000 megawatts.