Pressurized Water Reactor (PWR)

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The pressurised water reactor (PWR) is the most common type of nuclear power reactor in the world, accounting for around two-thirds of all reactors in operation. The VVER (an acronym derived from the Russian vodo-vodyanoy energetichesky reaktor) is a Soviet-developed type of pressurised water reactor. PWR technology was originally developed in the United States, while the VVER design evolved independently in the Soviet Union.

Ceramic uranium dioxide pellets, typically containing uranium enriched to around 3%—5% in uranium-235, are used as fuel. They are inserted into fuel rods that are assembled into fuel assemblies about 4 metres long. The reactor core is housed in a steel pressure vessel and is typically about 3.5 metres high and 3 metres in diameter. The reactor is periodically shut down for refuelling, typically every 12 to 24 months, when a portion of the fuel assemblies is replaced.

Light water is used as both the moderator and the coolant, making the PWR a type of light water reactor (LWR). Water circulates in the primary circuit at a pressure of about 15.5 MPa and leaves the reactor at a temperature of around 315 °C. The thermal energy is transferred in steam generator to water in the secondary circuit, where steam is produced to drive a turbine. A PWR nuclear power plant therefore uses a two-circuit arrangement.

Schematic diagram of a PWR.

Schematic diagram of a PWR.

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Video: View of the Watts Bar Nuclear Plant in the USA, with two Westinghouse pressurised water reactors.

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Cross-sectional diagram of a nuclear power unit with a PWR.

Cross-sectional diagram of a nuclear power unit with a PWR.

The San Onofre Nuclear Generating Station in California is located on the Pacific coast and originally had three pressurised water reactors. Unit 1 was permanently shut down in 1992, while Units 2 and 3 ceased operation in 2013 following problems with their replacement steam generators. All three units are now being decommissioned. (Source: © iofoto / stock.adobe.com)
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The Trillo Nuclear Power Plant in Spain consists of a single pressurised water reactor supplied by the German company KWU. With a gross electrical output of about 1,066 MWe, the plant began commercial operation in 1988. (Source: © Jose / stock.adobe.com)
The Trojan Nuclear Power Plant was Oregon’s only commercial nuclear power plant. Its pressurised water reactor began commercial operation in 1976 and was permanently shut down in 1993, primarily because of economic and reliability concerns associated with steam generator tube degradation. (Source: Wikipedia.org)
The Callaway Energy Center in Missouri, USA, operates a single Westinghouse pressurised water reactor with an electrical output of approximately 1,200 MW. (Source: © spiritofamerica / stock.adobe.com)
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Pressurised water reactors are also widely used to power nuclear submarines and aircraft carriers.

Nuclear Power Plant — PWR
Nuclear Power Plant — PWR On-line interactive 3D model

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