PWR

PWR
Name	Pressurized Water Reactor
Type	Nuclear reactor
Invented	1940s–1950s
Developer	Westinghouse Electric Company; Soviet Union research by Nikolay Dollezhal; designs by Framatome and General Electric
First critic	Shippingport Atomic Power Station
Fuel	Enriched Uranium-235; variants use Mixed oxide fuel
Coolant	Pressurized Light water reactor coolant
Moderator	Light water reactor moderator
Status	Widely deployed
Country	Multinational

PWR

A pressurized water reactor is a type of nuclear fission reactor that uses high‑pressure liquid water as both coolant and neutron moderator. It is a dominant commercial reactor class in civil nuclear power, deployed by companies and institutions such as Westinghouse Electric Company, Areva (now Framatome), General Electric, Rosatom, and national utilities in United States, France, Russia, Japan, South Korea, and China. The design emphasizes primary‑loop isolation, heat exchangers, and robust pressure boundary systems derived from early projects like Shippingport Atomic Power Station and research at Oak Ridge National Laboratory.

Overview

PWRs operate using enriched Uranium-235 fuel assemblies within a reactor vessel developed by firms like Westinghouse Electric Company and Framatome, producing heat transferred via a primary coolant loop to steam generators tied to secondary loops that drive turbines made by General Electric or Siemens. Major deployments occurred under national programs overseen by regulators such as the Nuclear Regulatory Commission in the United States, the Autorité de sûreté nucléaire in France, and the Nuclear Regulation Authority in Japan. Commercial fleets include reactor parks at sites like Dukovany Nuclear Power Station, Paluel Nuclear Power Plant, Ohi Nuclear Power Plant, and Kori Nuclear Power Plant.

Design and Components

Key components include a robust reactor pressure vessel produced to standards used by suppliers such as Mitsubishi Heavy Industries, a primary coolant pump system, steam generators often supplied by Babcock & Wilcox, control rod drive mechanisms developed by AREVA NP/Framatome, and containment structures modeled on precedents like the Three Mile Island Nuclear Generating Station and Fessenheim Nuclear Power Plant. Instruments include neutron flux detectors, coolant chemistry monitors, and emergency core cooling systems influenced by standards from International Atomic Energy Agency guidance and national design authorities such as Nuclear Energy Institute.

Operation and Safety Systems

Normal operation maintains the primary loop at high pressure to prevent boiling, with heat transferred to a secondary loop that produces steam for steam turbine generators connected to electrical grids managed by utilities like EDF and Tokyo Electric Power Company. Safety systems include redundant and diverse emergency core cooling systems, automatic reactor trip systems informed by lessons from Three Mile Island accident and Chernobyl disaster responses, passive safety features in modern designs inspired by research at Idaho National Laboratory, and containment buildings designed to withstand external events referenced in studies by Sandia National Laboratories.

Fuel and Reactor Core

Fuel assemblies use enriched Uranium-235 in zirconium alloy cladding developed from metallurgy research at Argonne National Laboratory and fabrication by industrial partners. Some operators use Mixed oxide fuel (MOX) as in deployments at Belgian Nuclear Research Centre collaborations, while advanced fuel cycle considerations reference work from Centre national de la recherche scientifique and Rosatom programs. Core design balances neutronics, thermal hydraulics, and burnup strategies evaluated using codes from institutions like Electric Power Research Institute and Institut de radioprotection et de sûreté nucléaire.

History and Development

The class emerged from mid‑20th century programs including the Shippingport Atomic Power Station project and research at Oak Ridge National Laboratory, with commercial evolution driven by companies such as Westinghouse Electric Company, General Electric, and Framatome. International adoption accelerated during the postwar era under national fleets in United States, France, Soviet Union, Japan, and later South Korea and China, influenced by policy decisions like those of Atoms for Peace proponents and standards shaped by International Atomic Energy Agency guidance and national regulators.

Incidents and Regulatory Response

Operational incidents have ranged from minor coolant leaks to significant events like the partial meltdown at Three Mile Island Nuclear Generating Station, prompting regulatory reforms by the Nuclear Regulatory Commission and international reviews by the International Atomic Energy Agency. Other operational learnings trace to adaptations following events at Fukushima Daiichi nuclear disaster and aging management insights from long‑term operation cases such as Beznau Nuclear Power Plant and Calvert Cliffs Nuclear Power Plant, with enhanced oversight by authorities like Office for Nuclear Regulation in the United Kingdom and Korean Nuclear Safety and Security Commission.

Variants and International Deployment

Variants include evolutionary designs from Westinghouse such as the AP1000‑influenced families, large units by Framatome in France (e.g., N4 series), and Soviet‑era pressurized water types developed under OKB Gidropress for deployment in Russia and export markets. Exported fleets operate at sites including Zaporizhzhia Nuclear Power Plant, Gravelines Nuclear Power Station, Ulchin Nuclear Power Plant, and Taishan Nuclear Power Plant, built under international partnerships involving EDF, China National Nuclear Corporation, and KHNP.

Category:Nuclear reactors