Protection against radioactivity.
Radioactivity describes the characteristic of unstable atomic nuclei to change spontaneously while releasing energy. The energy is released as ionising radiation. A nucleus' point of dissolution is incidental. An atomic nucleus becomes stable and breaks down no further when the lowest energy level has been reached.
Radioactive decay is not only used for producing energy. It is applied in technical fields (testing materials, measuring thickness) and in medical science (nuclear medicine, scintigraphy, fighting tumours, imaging techniques).
