In the fissioning of uranium, about one hundred dif­ferent radioactive nuclides are produced. The princi­pal fission products and their half-lives are shown in Table 4.1. In the radioactive decay process beta particles and gamma rays are emitted from most of the nuclides.

Activation products

The materials of reactor construction, the uranium fuel cladding and the reactor coolant are subject to neutron bombardment in the fission process. As a consequence, radionuclides are formed by neutron cap­ture and typical nuclides and their half-lives are shown in Table 4.2. Radioactive decay gives rise to emission of beta particles and gamma rays in general. The radioactive quantities of activation products that arise are considerably less than the fission products.