urani235

Uranium-235 (235U) is a fissile isotope of uranium, meaning it can sustain a nuclear chain reaction. It is one of three naturally occurring isotopes of uranium, along with uranium-238 and a trace amount of uranium-234. Naturally occurring uranium consists of about 99.27% uranium-238 and only about 0.72% uranium-235.

For most nuclear applications, such as power reactors and nuclear weapons, uranium must be enriched to increase the concentration of uranium-235. The process of enrichment typically involves separating uranium isotopes based on their slight mass difference.

When a uranium-235 nucleus absorbs a slow-moving neutron, it becomes unstable and undergoes fission. This fission process releases a significant amount of energy, along with more neutrons. These released neutrons can then go on to cause fission in other uranium-235 nuclei, leading to a self-sustaining chain reaction. This controlled chain reaction is the basis for nuclear power generation. In an uncontrolled chain reaction, the rapid release of energy results in a nuclear explosion.

Uranium-235 has a half-life of approximately 703.8 million years. Its discovery is attributed to the work of Alfred Nier, Edward Brevoort, Milton Grosse, and Enrico Fermi in 1938. The unique properties of uranium-235 have made it a cornerstone of nuclear technology, with significant implications for energy production and international security.