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Pressurised Water Reactors (PWRs) are the most common power reactor design worldwide, although other types are more widely used in Canada, Japan, and the UK, and they were historically the first type of power generation reactor designed, being used on the US Navy's first nuclear powered submarine[1] and subsequently on its first dedicated electricity power generation plant[2] at Shippingport.[3]

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, high pressure water flows through a steam generator: a heat exchanger in which it transfers thermal energy to water in a secondary system, which is at lower pressure and allowed to boil, producing steam which drives a turbines, which in turn drives an alternator to generate electricity.

Simple animation of a PWR power station Video with audio description of how a PWR power works

By comparison in a boiling water reactor (BWR) the water cooling the core boils and passes as steam directly to the turbines, so that type of reactor has no pressuriser or steam generator.

Both PWRs and BWRs use ordinary (light) water as both coolant and neutron moderator. Most PWRs use anywhere from 2 to 4 steam generators.

Most PWRs in current operation are designs dating from the late 20th century and are considered Generation 2 reactors. Newer designs such as the Korean Kepco APR1400, Russian VVER 1200, Chinese HPR1000 "Hualong One", US AP1000, and EPR have design improvements which classify them as Generation 3 or Generation 3+. Several Small Modular Reactors are also PWR designs.

Further reading

Footnotes and references

  1. Reactor History: The PWR and the Nautilus What is Nuclear
  2. The UK's electricity generating reactor at Calder Hall was primarily intended for producing plutonium for nuclear weapons
  3. Nuclear Reactor Development: The commercialisation of the pressurized water reactor What Is Nuclear