Nuclear Fission
Fission is the splitting of a large atom into two or more smaller ones. Fission reaction does not normally occur in nature. Fission produces many highly radioactive particles. Critical mass of the substance and high-speed neutrons are required. Takes little energy to split two atoms in a fission reaction. The energy released by fission is a million times greater than that released in chemical reactions, but lower than the energy released by nuclear fusion. One class of nuclear weapon is a fission bomb, also known as an atomic bomb or atom bomb. Fission is used in nuclear power plants. Uranium is the primary fuel used in power plants.
Nuclear Fusion
Fusion is the fusing of two or more lighter atoms into a larger one. Fusion occurs in stars, such as the sun. Few radioactive particles are produced by fusion reaction, but if a fission "trigger" is used, radioactive particles will result from that. High density, high temperature environment is required. Extremely high energy is required to bring two or more protons close enough that nuclear forces overcome their electrostatic repulsion. The energy released by fusion is three to four times greater than the energy released by fission. One class of nuclear weapon is the hydrogen bomb, which uses a fission reaction to "trigger" a fusion reaction. Fusion is an experimental technology for producing power. Hydrogen isotopes (Deuterium and Tritium) are the primary fuel used in experimental fusion power plants.
