Atomic energy is the source of power for both nuclear reactors and nuclear weapons. This energy comes from the fission or fusion of atoms. ‘What are nuclear weapons?’ explains how a nuclear weapon works by looking at the characteristics of an atom and charts the discovery of the power of the atom for destructive purposes. The peaceful end of the Cold War did not mean the end of nuclear threats. We don't like to imagine the scenario of the use of nuclear weapons today. The task of caring for the injured would literally be beyond the ability of any medical system to respond.