- They 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 released 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.