The nuclear fuel cycle is inseparable from any other activity in the industry. It incorporates every activity, from operating uranium mines, to uranium conversion and enrichment, fuel fabrication, recycling, and processing of spent fuel, and finally the deep disposal of residual waste. Working in the fuel cycle means working in the nuclear industry. Before it can be used, be it in a reactor for electricity production or in an experimental reactor, the uranium has to be extracted from the ore, and then transformed and enriched. Fuel fabrication then follows.
The same applies at the end of the cycle. After use in a reactor, the spent fuel is processed and, depending on the chemical species, reconditioned as fuel or stored awaiting deep storage.
These two major stages, upstream and downstream, are critical in the nuclear industry. But what are they exactly?
Everything starts in the mines, where the natural uranium ore is extracted. The uranium is then concentrated in the form of "yellow cake" before being sent to an enrichment and conversion facility.
Enrichment is a technique that takes the uranium 235 content from 0.7% to about 3% (for PWR fuel) and up to 20% (for experimental reactors).
After enrichment, the uranium undergoes further chemical transformations to produce uranium dioxide which is made into fuel pellets and placed inside a zirconium alloy cladding. These are the fuel rods.
After use in a reactor, the spent fuel is cooled and then sent to a treatment plant. Uranium, plutonium, and residual waste (minor actinides, fission products) are chemically separated and then transferred to the appropriate sectors.
Uranium can be used to produce new fuel, plutonium is sometimes used to produce MOX fuel, and the waste is vitrified and stored prior to final disposal.
Sofren operates in the areas outlined above, both upstream (involved in the design and construction of the Georges Besse II enrichment plant) and downstream (numerous projects in partnership with industry key players and in the fuel reprocessing plant in The Hague).