uranu238

Uranium-238, commonly written as U-238, is the most abundant isotope of natural uranium. It has atomic number 92 and a mass number of 238, and accounts for about 99.3% of natural uranium. U-238 is a long-lived radioactive nuclide.

It decays by alpha emission to thorium-234, which beta decays to protactinium-234 and then through additional beta decays to stable lead-206. The U-238 decay chain continues through several intermediates before reaching lead-206, making it a key part of uranium’s natural radioactivity and dating capabilities.

Occurrence and production: U-238 occurs in uranium-bearing minerals such as uraninite and pitchblende. It is extracted during mining and milling of uranium ore and remains the dominant isotope in commercially mined uranium.

Uses and significance: Although U-238 is not fissile, it is fertile, meaning it can capture a neutron to become plutonium-239, a fissile material used in some reactor fuels and, in some cases, in nuclear weapons. Because of its long half-life, U-238 is central to uranium-lead dating, one of the oldest radiometric dating methods used to determine the ages of rocks and minerals. The element’s high density and chemical properties also contribute to its use in shielding and specialized industrial applications.

History and naming: The element uranium was named after the planet Uranus and was discovered in 1789 by Martin Heinrich Klaproth. Its most abundant isotope, U-238, underpins much of the science and technology associated with uranium.