Classification by generation

• Generation I reactor
• Generation II reactor
• Generation III reactor
• Generation IV reactor

Classification by phase of fuel

• Solid fueled
• Fluid fueled
• Gas fueled

Classification by use

• Electricity
• Power plants
• Propulsion, see nuclear propulsion
• Nuclear marine propulsion
• Various proposed forms of rocket propulsion
• Other uses of heat
• Desalination
• Heat for domestic and industrial heating
• Hydrogen production for use in a hydrogen economy
• Production reactors for transmutation of elements
• Breeder reactors. Fast breeder reactors are capable of enriching Uranium during the fission chain reaction (by converting fertile U-238 to Pu-239) which allows an operational fast reactor to generate more fissile material than it consumes. Thus, a breeder reactor, once running, can be re-fueled with natural or even depleted uranium.^[4]
• Creating various radioactive isotopes, such as americium for use in smoke detectors, and cobalt-60, molybdenum-99 and others, used for imaging and medical treatment.
• Production of materials for nuclear weapons such as weapons-grade plutonium
• Providing a source of neutron radiation (for example with the pulsed Godiva device) and positron radiation (e.g. Neutron activation analysis and Potassium-argon dating)
• Research reactors : Typically reactors used for research and training, materials testing, or the production of radioisotopes for medicine and industry. These are much smaller than power reactors or those propelling ships, and many are on university campuses. There are about 280 such reactors operating, in 56 countries. Some operate with high-enriched uranium fuel, and international efforts are underway to substitute low-enriched fuel.