Related Terms. Ratio of the density of a substance at 20Â°C or 68Â°F to the density of water at 4Â°C or 39.2Â°F.
Nuclear fission. NUCLEAR FISSION. Nuclear fission is a reaction in which an atom's nucleus is broken apart, releasing a tremendous amount of energy. Nuclear fission is used in many power plants on Earth (and is used in atomic weapons). nuclear fission: Reaction that splits nuclei into less massive fragments.nuclear fusion: Reaction that joins the nuclei of atoms to form more massive nuclei. - (n.). The splitting of an atomic nucleus into two large fragments. nuclear fusion - (n.) ... ~ reactors naturally produce free neutron s; their role is to sustain the energy-producing chain reaction.
Nuclear fission is the splitting (hence the term fission) of a heavy nucleus into two smaller nuclei. Typically involved is uranium-235 or plutonium-239. Nuclear fusion is tâ¦he combining (hence the term fusion) of two light nuclei into one larger nucleus. Typically involved is hydrogen-2 (deuterium) or hydrogen-3 (tritium).