Nuclear power plants, which supply America with 20 percent of its electricity, require uranium – a naturally occurring metal – to run. uranium in its natural state, however, cannot be loaded into or consumed by nuclear power plants. It must go through a series of operations to become usable.

After uranium ore is mined, it is processed into a concentrated form, which is called yellow cake, given its powdery consistency. Impurities are removed and then the yellow cake is converted into gaseous uranium hexafluoride, a suitable form for enrichment.

Further Refinement

At this stage, the uranium hexafluoride still must be further refined, or enriched. The ultimate goal of enrichment is to increase the amount of a specific element, uranium 235, in the uranium hexafluoride gas. uranium 235 is the key building block of nuclear power plant fuel. 

Natural uranium contains less than one percent of uranium 235, which is not enough to be used in a nuclear reactor. The enrichment process increases the amount of uranium 235 from less than 1 percent to between 3 percent and 6 percent, making it usable as fuel for modern nuclear power plants.

There are two ways to enrich uranium:

• Gaseous diffusion
  
  
• Centrifuge technology

Gaseous diffusion, the first AREVA industrialized separation technology, involves passing uranium gas through porous barriers to separate out the needed element, uranium 235. There now exists, however, a more advanced technology, the centrifuge process, which is much more effective, using 50 times less electricity than gaseous diffusion.

During the centrifuge process, uranium gas is separated by high-speed rotation in a vacuum-sealed cylinder. The centrifugal force created by the rotation pushes the heavier particles in the gas outward towards the cylinder wall, where they fall to the bottom. The lighter uranium 235 particles migrate to the center, where they are transported upward and captured. This method allows the manufacturer to increase the percentage of uranium 235 in the uranium.

Once the uranium gas is enriched in uranium 235, it is cooled to form a solid crystal. It is then shipped to a fuel fabrication facility where it eventually will be processed into the fuel rods that are used to generate electricity at nuclear power plants.