The nuclear fuel cycle consists of the following activities: uranium mining and calcining, conversion, enrichment, fuel fabrication, power generation and spent fuel management.

The Mining and Calcining Process

Historically, uranium has been extracted from both open-pits and underground mines. In recent times, alternative techniques such as in-situ leach mining, in which solutions are injected into the underground deposits to dissolve uranium, have become more widely used.

Mined ore is milled and the uranium extracted via a multi-stage metallurgical process. The resulting uranium-rich slurries are then calcined to produce uranium concentrate, U3O8, a brownish powder that contains approximately 90% uranium oxide.

Conversion and Enrichment

Most nuclear reactors require uranium that has a higher proportion of U235 than that present in naturally occurring uranium. In order to increase the level of U235, uranium concentrates must first undergo a chemical conversion process into uranium hexafluoride, UF6.

Thereafter, the UF6 must undergo a process used to increase the amount of U235 known as uranium enrichment. Via the enrichment process, the U235 level is raised from the naturally occurring level of 0.71% to levels in the range of 3-5%.

Fuel Fabrication

In order to fabricate fuel for use in nuclear power stations the enriched UF6 needs to be deconverted to uranium dioxide, (UO2). This then undergoes various processes resulting in ceramic UO2 fuel pellets which are loaded into metal fuel pins then configured into nuclear fuel assemblies.

Power Generation and Spent Fuel Management

Nuclear fuel assemblies are loaded into nuclear reactors and 'burned' to produce electricity. A variety of reactor types are in operation around the world although predominant designs are varieties of water-cooled reactors of the Boiling Water ("BWR") or Pressurised Water ("PWR") types.

After several years in-reactor the U235 in the fuel has mostly been used up and the fuel assemblies are discharged into a temporary cooling pond at the reactor site. The spent nuclear fuel must now be dealt with and this can be via long-term storage, geological disposal or by reprocessing the fuel to recover unused uranium and plutonium.