What is "pressurized water reactor"

n. A form of nuclear power plant in which heat from the reactor is transferred via a continuous flow of pressurized water

n. a nuclear reactor that uses water as a coolant and moderator; the steam produced can drive a steam turbine [syn: PWR]

Pressurized water reactors (PWRs) constitute the large majority of the world's nuclear power plants (notable exceptions being the United Kingdom, Japan and Canada) and are one of three types of light water reactor (LWR), the other types being boiling water reactors (BWRs) and supercritical water reactors (SCWRs). In a PWR, the primary coolant ( water) is pumped under high pressure to the reactor core where it is heated by the energy generated by the fission of atoms. The heated water then flows to a steam generator where it transfers its thermal energy to a secondary system where steam is generated and flows to turbines which, in turn, spin an electric generator. In contrast to a boiling water reactor, pressure in the primary coolant loop prevents the water from boiling within the reactor. All LWRs use ordinary water as both coolant and neutron moderator.

PWRs were originally designed to serve as nuclear marine propulsion for nuclear submarines and were used in the original design of the second commercial power plant at Shippingport Atomic Power Station.

PWRs currently operating in the United States are considered Generation II reactors. Russia's VVER reactors are similar to U.S. PWRs. France operates many PWRs to generate the bulk of its electricity.