The Nuclear Fuel Cycle
The nuclear fuel cycle is a complex cycle which consists of a series of stages and steps that nuclear fuel material progress through, from cradle to grave.
Although Uranium is the most used nuclear fuel material and the nuclear fuel cycle usually refers to the uranium fuel cycle, it is worth noting that other cycles exist like the plutonium cycle and thorium cycle which are part of the nuclear fuel cycle.
The nuclear fuel cycle starts with the birth of the nuclear fuel material (mining of uranium) and ends its burial (disposal as nuclear waste), it typically includes the following stages:
- Mining: to recover uranium ore, the ore usually contains 0.1 – 15% uranium depending on the uranium mine.
Milling: of the ore to produce uranium concentrate that usually contains more than 80% uranium, commonly known as 'yellowcake'
Refining: The uranium concentrate (U3O8) is refined to produce uranium dioxide (UO2).
Conversion: Uranium dioxide is converted into gaseous uranium hexafluoride (UF6) ready for enrichment.
Enrichment: a very sensitive and advanced technology, a physical stage during which the concentration of the U235 isotope is increased in the UF6
Fuel Manufacturing: The enriched UF6 is converted into the desired fuel material.
Fuel Fabrication: The uranium fuel is pressed into pellets and stacked in rods, or rolled in plates or other forms for use in reactors
Fuel Burnup: Nuclear fuel is loaded into a reactor and burned (nuclear reaction).
Spent Fuel: Highly radioactive consumed fuel is removed from the reactor and stored on-site for no less than five years.
Reprocessing: spent fuel is reprocessed to recover uranium and/or plutonium, to manufacture new fuel elements, and close the nuclear fuel cycle.
Final Disposal: Spent fuel is permanently disposed of; the first permanent disposal is expected in the 2020’s.