ABSTRACT
Nuclear energy can be liberated by two different processes, fission and fusion. In fission a heavy nucleus (uranium, plutonium, etc) is split into two or more fragments by bombardment of neutrons, simultaneously producing large amounts of energy. If uranium235, consisting of 143 neutrons and 92 protons, is bombarded it produces 200 MeV for each nucleus that undergoes fission, two or three neutrons and also two radioactive nuclei. Fusion occurs when two light nuclei of hydrogen isotopes unite and undergo a fusion reaction from which neutrons of several MeV are emitted. For reaction of the hydrogen isotopes deuterium and tritium, the most studied process, a 14.1 MeV neutron is produced, and in addition an alpha particle, an He-4 nucleus, of 3.5 MeV. In the process an intermediate compound nucleus of two protons and three neutrons is formed which is unstable and immediately splits into a neutron and an alpha particle.
