Salient. An Organ of Student Opinion at Victoria University College, Wellington N.Z. Vol. 20, No. 6. May 9, 1957
In an ordinary atomic bomb or a nuclear reactor (atomic pile) energy is obtained by breaking the nucleus of some heavy element such as uranium or plutonium into two parts (fission). The energy of the heavy original nucleus is greater than the sum of the energies of the two pieces resulting from the fission, and so the two pieces fly apart with considerable energy. This heats up the material around them, in a bomb the heat is generated in a tiny fraction of a second so the effect is explosive, in a reactor the process is carefully controlled, the heat is generated over a relatively long period and may be used to drive turbines, etc., to give useful power.
The two smaller nuclei which result from the fission of the heavy uranium give atoms which have normal chemical reactions and are in most respects no different from atoms found in the world about us. But their birth is somewhat unnatural and they are slightly unbalanced in their construction. They have more neutrons in them than is proper. This makes them unstable and most of them keep on shooting out electrons until they are stable. This is called radioactivity. The fast electrons shot out of the nucleus are called beta rays, in the process several penetrating kind of X-rays called gamma rays are also produced.