Nuclear fuel

Nuclear fuel is a material that can be burned by nuclear fission or fusion to derive nuclear energy. The most common nuclear fuels are uranium-235 and plutonium-239. Before uranium can be used in nuclear power plants, it must first be enriched.

Uranium mines operate in some twenty countries, though about half of world production comes from just ten mines in six countries, in Canada, Australia, Niger, Kazakhstan, Russia and Namibia.

Uranium resources can be extracted from the ground in three ways: open pit, underground, and in-situ leach (ISL).

The milling process involves crushing and pulverizing the rock into very fine fragments and adding water to create slurry. This slurry is then mixed with sulfuric acid or an alkaline solution to release the uranium from the host rock. 

The vast majority of all nuclear power reactors require 'enriched' uranium fuel in which the proportion of the uranium-235 isotope has been raised from the natural level of 0.7% to about 3.5% to 5%.  The enrichment process needs to have the uranium in gaseous form, so on the way from the mine it goes through a conversion plant which turns the uranium oxide into uranium hexafluoride (UF6).

The enrichment plant concentrates the useful U-235, leaving about 85% of the uranium by separating gaseous uranium hexafluoride into two streams: One stream is enriched to the required level of U-235 and then passes to the next stage of the fuel cycle.  The other stream is depleted in U-235 and is called 'tails' or depleted uranium.  It is mostly uranium-238 and has little immediate use. 

Enriched UF6 is transported to a fuel fabrication plant where it is converted to uranium dioxide (UO2) powder. This powder is then pressed to form small fuel pellets, which are then heated to make a hard ceramic material. The pellets are then inserted into thin tubes to form fuel rods. These fuel rods are then grouped together to form fuel assemblies, which are several meters long.

Because nuclear plants refuel every 18-24 months, they are not subject to fuel price volatility like natural gas and oil power plants.

 Nuclear power plants have achieved the lowest production costs between coal, natural gas and oil.

Finally; Fuel costs make up 30 percent of the overall production costs of nuclear power plants but fuel costs for coal, natural gas and oil, however, make up about 80 percent of the production costs.