A more commonly used unit is the rad, which is a hundredth of a gray. 0.01 gray Different kinds of radiation have different levels of effectiveness when it comes to ionizing molecules in living tissue. The absorbed dose really needs to be corrected for this, and the correction is an easy one. If a uranium atom absorbs a neutron it will be unstable, and will generally split into two fragments. This process, the splitting of a large nucleus into two smaller ones, is known as nuclear fission.
Many nuclear reactors use uranium as fuel to generate electricity.
Although radioactive by-products are produced in the reactor, generating electricity in a nuclear reactor is much more efficient than using a chemical process, such as burning oil, gas, or coal. The chemical processes that occur during burning produce a few eV of energy per molecule. Such neutrons, with kinetic energy of 0.04 eV or less, are known as thermal neutrons. When a thermal neutron hits a U-235 nucleus and is absorbed, the nucleus generally splits into two big pieces and a few neutrons. These neutrons have kinetic energies of several MeV, however, and this energy must be removed so the neutron becomes a thermal neutron and can be used to break apart another uranium nucleus.