Conversion, Enrichment and Fuel Fabrication
Most nuclear power plants use fuel enriched with the isotope U235. To do this the uranium oxide from the mine site is converted to a gas, UF6, which is then enriched to U235 either by diffusion – exploiting the different speeds U235 and U238 travel through a membrane or centrifuge – passing the gas through spinning cylinders, the centrifugal force moving the heavier U238 to the outside of the cylinder and concentrating U235 in the centre. These processes increase the concentration of U235 in the uranium oxide to around 4- 5%.
Enriched uranium oxide pellets are then produced and coated in stainless steel to form rods. These are then sealed and assembled in clusters for use in the nuclear power plants.
Further information can be found here: http://world-nuclear.org/info/Nuclear-Fuel-Cycle/Introduction/Nuclear-Fuel-Cycle-Overview/
Used Fuel Management
The used fuel is first stored to allow most of the radioactivity to decay. It can then be reprocessed or recycled into a Mixed Oxide Fuel (“MOX”) for re-use in nuclear power plants or prepared for long term storage.
There are several long-term underground storage facilities planned but as yet none have been built. The total volume for all the world’s nuclear waste is very small, especially when compared with other, often more toxic, industrial waste. The total volume of material for one year from the world’s 400+ nuclear power plants would fit in a 2 storey building built over a basketball court.