The activity concentration arising solely from the decay of the uranium isotopes (U-234, U-235 and U-238) found in natural uranium is 25.4 Bq per mg. In nature, uranium isotopes are typically found in ...

Uranium is a radioactive element, meaning its atoms are unstable and decay over time ... A different isotope, uranium-235, is used in nuclear reactors and weapons, as U-238 cannot sustain a ...

and the time it takes for one-half of a particular isotope to decay is its radioactive half-life. For example, about 1.5 percent of a quantity of Uranium 238 will decay to lead every 100 million ...