A pressurized water reactor is a nuclear reactor which employs heavy water under pressure as a coolant agent. A nuclear reactor is a large vat-like, sealed container where controlled nuclear chain reaction is carried out using long uranium rods. In a power plant, the nuclear reaction generates heat, which transforms the water in the large tank into steam. Then the pressurized steam is conveyed through a pipe to the turbine that drives an AC generator. The heat produced by the rods of uranium is due to the release of energy in the form of particles of atoms. The heavy water utilized can be either deuterium or tritium, which are hydrogen with a heavy nucleus containing one or two neutrons, respectively.
The pressurized water reactor was first used in nuclear submarines. The first civilian PWR was manufactured at Shippingport, in 1956, and it was put in operation in 1957. It was a 60 MW reactor which employed high enrichment uranium fuel. It would be followed by the Yankee Rowe Power Plant, which also utilized uranium oxide fuel. Over the years, the new nuclear plants that entered in service were increased in generation capacity, in regard to the size of components, the number of coolant loops, and overall improvements in designs. Modern PWR can generate up to 1,400 MW (Net).
A PWR basically consists of the reactor pressure vessel, which contains the core (where the atomic fission takes place), core barrels (rods), and the primary circuit loops that transmit the heat to the steam generators, and the secondary loops that conveys the steam to the turbine, plus control and safety systems. The primary side pressure is regulated by a pressurizer on one of the primary loops. The primary circuit in enclosed in a containment. Up until a few years ago, the main vendors in the USA were Westinghouse, Babcock and Willcox, and Combustion Engineering. In Germany, Kraftwerk Union used to be the main vendor, while Framatom was the French company.
Below, pressurized water reactor in a nuclear power plant
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