A nuclear reactor is a device that can manage a self-sustaining series of nuclear-fission reactions. Neutrons freed in one reaction may hit other heavy nuclei, causing them to split. Fission is the process in which a nucleus splits into two smaller pieces. A large amount of energy is released in this process.
In a nuclear reactor the chain reaction is maintained at a steady pace. The rate of this chain reaction is controlled by materials, usually in the form of rods that take in neutrons. Nuclear reactors are designed so they can't blow up like atomic bombs. Control rods made of boron are gradually placed in the core if the series begins to continue too fast, which could destroy the core. The heat released by fission is removed from the core by a coolant circulated through the core. Some of the energy is used to heat up water and convert it to steam.
This steam runs a turbine, and the turbine's energy is turned into electricity by a generator. Besides providing an important source of electric power, nuclear reactors are also used to fuel certain types of military machines, submarines, and some spacecrafts. Another major use of reactors is the creation of radioactive isotopes that are used in scientific research and medical therapy.
Most of the energy of fission--about 85 percent of it--is released within a very short time after the process occurs. The rest of the energy comes from the radioactive decay of fission wastes, which is what the leftovers are called after they have emitted neutrons. Radioactive decay continues when the fission series has been stopped.
A breeder reactor is a nuclear reactor that produces more fissionable material than it consumes to create energy. This type of reactor is designed to lengthen the nuclear fuel supply...