Radiometric dating is a method used to date rocks and other objects based on the known decay rate of radioactive isotopes. The two uranium isotopes decay at different rates, and this helps make uranium-lead dating one of the most reliable methods because it provides a built-in cross-check.

What does uranium dating do?

As its name suggests, uranium-series dating uses the radioactive decay of uranium to calculate an age. When uranium decays, it goes through a series of decays until it eventually reaches a stable isotope. So, for example, uranium 238 will decay to uranium 234, which will decay to thorium 230.

Why is U-238 not used as a fuel?

Uranium-235 (natural abundance 0.71%) is very scarce and difficult to separate from uranium-238 (natural abundance 99.28%). The much more abundant uranium-238 does not undergo fission and therefore cannot be used as a fuel for nuclear reactors.