Uranium Enrichment

Explanation :

• Natural uranium is composed of various isotopes, or different types of uranium. It contains approximately 99.3% of the isotope uranium-238, and has only very small concentrations, about 7%, of the fissile isotope uranium-235. An isotope is considered fissile if it can be split by a slow moving neutron.
• Uranium-235 is the most significant fissile isotope of uranium for reactor fuel and nuclear weapons.
• Uranium needs to be in a gaseous form for enrichment due to the varying chemical and physical properties the different isotopes (U-235 and U-238) have.
• Commercially, the U235 isotope is enriched to 3 to 5% (from the natural state of 0.7%) and is then further processed to create nuclear fuel.
• At the conversion plant, uranium oxide is converted to the chemical form of uranium hexafluoride (UF6) to be usable in an enrichment facility.

Stages of Enrichment

• Uranium enriched to concentrations above 0.7% but less than 20% uranium-235 is defined as low enriched uranium (LEU). Most nuclear reactors use LEU that is about 3-5% uranium-235.
• Uranium enriched to more than 20% uranium-235 is defined as highly enriched uranium (HEU). All HEU is weapons-usable, but the lower the enrichment level the greater the amount of material required to achieve a critical mass - the amount of material required to build a bomb.
• States with nuclear weapons typically use so-called weapons-grade HEU, which is typically defined as 90% HEU or above, to minimize weapons’ size.