The nuclear fuel cycle starts with mining and milling of the uranium ore, uranium conversion factory, the enrichment plant, the fuel fabrication plant, the reactor, the spent fuel storage on site and then 2 options either the once through leading to storage in huge special casks of spent fuel or the reprocessing one leading to separation of used uranium, plutonium, minor actinides and fission products, waste management and storage. All the steps include transportation with different means and casks depending on the transported products.
The nuclear fuel cycle is composed of the following activities:
- mining uranium ore deposit - usually containing 1kg U per ton,
- milling it through chemical treatment to concentrate it resulting in the creation of the famous yellow cake,
- uranium conversion into hexafluoride UF6 to prepare it for enrichment,
- uranium isotopic enrichment which means increasing the proportion from natural concentration of 0.7%to the required
isotopic concentration around 4% for the fuel of light water reactors today,
- fuel fabrication: fuel elements for Light Water Reactors are rods in which the uranium at the right isotopic
concentration is filled in the form of UO2 pellets. The fuel rods are then assembled in usually square arrays
called the fuel assemblies and then sent to the reactors as “fresh fuel”,
- reactors which burn the fuel up the time where it has to be unloaded from the reactor core when having reached
the high burn up permitted,
- spent fuel storage: after unloading the used fuel it is stored on the reactor site in special water pools to wait for
the decay of the heat production of the fuel assembly which takes around a year,
- then 2 different options:
* Open fuel cycle also called “once through” in which one send for intermediate and later final storage the
fuel assemblies themselves in dry massive casts,
* Closed fuel cycle where the fuel assemblies are transported in dry massive shipping casts to the reprocessing plant,
- reprocessing plant: it is the place where the separation of the various components to treat them separately
(95% uranium, 1% plutonium, fission products and minor actinides), and the final result is uranium which can be re-
enriched, PuO2 recycled with UO2 for fabrication of MOX fuel. The other products are highly radioactive
wastes bonded in a glass matrix for long term storage.
- radioactive waste management and final storage.