Fabrication of the fuel and its subsequent reprocessing after it has been used in the nuclear reactors constitute the fuel cycle. However, by convention, the cycle begins with extraction of the uranium ore and ends with disposal of a range of radioactive wastes arising from the spent fuel.
The uranium ore is extracted, then purified and concentrated into “yellow cake” on the mining sites. The solid yellow cake is then converted into uranium hexafluoride gas (UF6) during the conversion operation. This fabrication of the raw material for enrichment is carried out by COMURHEX in Malvési (Aude département1) and Pierrelatte (Drôme département). The installations involved – which are not regulated as basic nuclear installations (BNIs) – use natural uranium whose uranium 235 content is about 0.7%.
Most of the world’s reactors use uranium which is slightly enriched with uranium 235. For example, the pressurised water reactor (PWR) series requires uranium enriched to between 3 and 5% with isotope 235. Raising the isotopic content of uranium 235 from 0.7% to between 3 and 5% is the role of the EURODIF plant in Tricastin, which separates the uranium hexafluoride by means of a twin-stream gaseous diffusion process, with one stream becoming enriched in uranium 235 while the other becomes depleted during the course of the process.
The process used in the FBFC plant at Romans-sur-Isère transforms the enriched uranium hexafluoride into uranium oxide powder. The fuel pellets manufactured with this oxide are clad to make up the fuel rods, which are then combined to form the fuel assemblies. These assemblies are then placed in the reactor core where they release power by fission of the uranium 235 nuclei.
|
Fabrication of the fuel and its subsequent reprocessing after it has been used in the nuclear reactors constitute the fuel cycle. However, by convention, the cycle begins with extraction of the uranium ore and ends with disposal of a range of radioactive wastes arising from the spent fuel. 
