Typical fission events release about two hundred million eV of energy for each fission event. By contrast, most chemical oxidation reactions (such as burning coal or TNT ) release at most a few eV per event, so nuclear fuel contains at least ten million times more usable energy than does chemical fuel. The energy of nuclear fission is released as kinetic energy of the fission products and fragments, and as electromagnetic radiation in the form of gamma rays ; in a nuclear reactor, the energy is converted to heat as the particles and gamma rays collide with the atoms that make up the reactor and its working fluid , usually water or occasionally heavy water . 1 electron volt = 1.60217646 × 10-19 joules 1 electron volt = 1.60217646 × 10-19 joules
In nuclear physics and nuclear chemistry , nuclear fission is a nuclear reaction in which the nucleus of an atom splits into smaller parts, often producing free neutrons and lighter nuclei , which may eventually produce photons (in the form of gamma rays ). Fission of heavy elements is an exothermic reaction which can release large amounts of energy both as electromagnetic radiation and as kinetic energy of the fragments ( heating the bulk material where fission takes place). For fission to produce energy, the total binding energy of the resulting elements has to be higher than that of the starting element. Fission is a form of nuclear transmutation because the resulting fragments are not the same element as the original atom. The atomic number, Z , should not be confused with the mass number , A , which is the total number of protons and neutrons in the nucleus of an atom. The number of neutrons, N , is known as the neutron number of the atom; thus, A = Z + N . Since protons and neutrons have approximately the same mass (and the mass of the electrons is negligible for many purposes), the atomic mass of an atom is roughly equal to A .