ABSTRACT
Five basic types of nuclear power plants can be commonly found in the world today. These are: pressurized water reactors, boiling water reactors, heavy water reactors, gas-cooled reactors, and liquid metal fast breeder reactors. These reactors use different combinations of coolants and different types of fuel to generate the power the world needs. The ability of a reactor to produce electric power over long periods of time is dependent upon the type of coolant, the composition of the core, and the enrichment of the fuel. Many factors go into selecting a reactor coolant, and some of the most important factors include cost, availability, neutronic performance, and thermal-hydraulic performance. Reactor coolants can be further subdivided into three broad categories: Fluids, liquid metals and gases. The cladding separates the fuel from the coolant, and in the case of a light water reactor, the coolant also serves as the moderator.
