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A boiling water reactor (BWR) is a type of nuclear reactor used for the generation of electrical power. It is the second most common type of electricity-generating nuclear reactor after the pressurized water reactor (PWR). BWR are thermal neutron reactors, where water is thus used both as a coolant and as a moderator, slowing down neutrons.
Due to the requirement to load a pressurized water reactor's primary coolant loop with boron, undesirable radioactive secondary tritium production in the water is over 25 times greater than in boiling water reactors of similar power, owing to the latter's absence of the neutron moderating element in its coolant loop. The tritium is created by ...
The progenitor of the BWR line was the 5 MW Vallecitos Boiling Water Reactor (VBWR), brought online in October 1957. Six design iterations, BWR-1 through BWR-6, were introduced between 1955 and 1972. This was followed by the Advanced Boiling Water Reactor (ABWR) introduced in the 1990s and the Economic Simplified Boiling Water Reactor (ESBWR ...
Most reactor systems employ a cooling system that is physically separate from the water that will be boiled to produce pressurized steam for the turbines, like the pressurized-water reactor. But in some reactors the water for the steam turbines is boiled directly by the reactor core, for example the boiling-water reactor.
The Reactor Protection System (RPS) is a system, computerized in later BWR models, that is designed to automatically, rapidly, and completely shut down and make safe the Nuclear Steam Supply System (NSSS – the reactor pressure vessel, pumps, and water/steam piping within the containment) if some event occurs that could result in inadvertant criticality.
Water pressure in a closed system tracks water temperature directly; as the temperature goes up, pressure goes up and vice versa. To increase the pressure in the reactor coolant system, large electric heaters in the pressurizer are turned on, raising the coolant temperature in the pressurizer and thereby raising the pressure. To decrease ...
Whilst most power reactors do have a pressure vessel, they are generally classified by the type of coolant rather than by the configuration of the vessel used to contain the coolant. The classifications are: Light-water reactor - Includes the pressurized water reactor and the boiling water reactor. Most nuclear power reactors are of this type.
The coolant (treated water), which is maintained at high pressure to prevent boiling, is pumped through the nuclear reactor core. Heat transfer takes place between the reactor core and the circulating water and the coolant is then pumped through the primary tube side of the steam generator by coolant pumps before returning to the reactor core.