Auxiliary feedwater is a backup
water
Water (chemical formula ) is an Inorganic compound, inorganic, transparent, tasteless, odorless, and Color of water, nearly colorless chemical substance, which is the main constituent of Earth's hydrosphere and the fluids of all known living ...
supply system found in
pressurized water reactor
A pressurized water reactor (PWR) is a type of light-water nuclear reactor. PWRs constitute the large majority of the world's nuclear power plants (with notable exceptions being the UK, Japan and Canada). In a PWR, the primary coolant (water) i ...
nuclear power plants (PWRs). This system, sometimes known as emergency feedwater, can be used to cool the reactor, if normal feedwater to the
steam generators
A steam generator is a form of low water-content boiler, similar to a flash steam boiler. The usual construction is as a spiral coil of water-tube, arranged as a single, or monotube, coil. Circulation is once-through and pumped under pressure, ...
fails to work. It works by pumping water to the steam generators from reserve tanks or a larger body of water (e.g. lake, river, or ocean) to remove
decay heat
Decay heat is the heat released as a result of radioactive decay. This heat is produced as an effect of radiation on materials: the energy of the alpha, beta or gamma radiation is converted into the thermal movement of atoms.
Decay heat occur ...
from the
reactor by dumping non-radioactive steam to atmosphere or using this steam to drive turbine driven auxiliary feedwater pump(s). The auxiliary feedwater system in PWRs are often equipped with ''motor driven'' aux feedwater pumps, and, as an additional measure, ''turbine driven'' aux feedwater pump that is driven not by electricity but by steam generated by decay heat removal from the normal secondary side steam circuit of the plant. In contrast to
emergency core cooling systems for
loss-of-coolant accident
A loss-of-coolant accident (LOCA) is a mode of failure for a nuclear reactor; if not managed effectively, the results of a LOCA could result in reactor core damage. Each nuclear plant's emergency core cooling system (ECCS) exists specifically t ...
s, the auxiliary feedwater system does not inject directly into the reactor core. Instead, it cools in an indirect manner by cooling the primary circuit with the reactor via the steam generators.
Nuclear technology
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