Through enrichment process, concentration of which uranium isotope is increased in the natural uranium?

The enrichment process is primarily used to increase the concentration of U-235 in natural uranium.
Important PointsUranium is a heavy metal that naturally occurs in the Earth's crust. It is approximately 99.3% Uranium-238 (U-238) and 0.7% Uranium-235 (U-235) by weight. A less common isotope, Uranium-234 (U-234), also exists in trace amounts.

• Uranium-235 is of particular interest because it is "fissile," meaning it can sustain a nuclear chain reaction.
• When a neutron strikes the nucleus of a U-235 atom, the nucleus splits, releasing a large amount of energy (the principle behind both nuclear power reactors and nuclear weapons) and more neutrons, which can then trigger more fissions.
• Uranium-238, the most common isotope, is not fissile, but is "fertile." This means that it can be transformed into other fissile materials (like Plutonium-239) under certain conditions.
• The level of enrichment needed depends on the intended use. For most nuclear power reactors, a moderate level of enrichment (3-5% U-235) is sufficient.
• However, for research reactors or nuclear weapons, "highly enriched uranium" (with over 20% U-235, and typically above 85% for weapons) is required.

Additional Information

• Safety and non-proliferation are significant concerns in the process of uranium enrichment, given the potential misuse of highly enriched uranium for illicit nuclear weapons.
• As a result, uranium enrichment activities are subject to strict international regulations and monitoring