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An open heat exchanger is one in which extracted steam is allowed to mix with the feedwater. This kind of heater will normally require a feed pump at both the feed inlet and outlet since the pressure in the heater is between the boiler pressure and the condenser pressure. A deaerator is a special case of the open feedwater heater which is ...
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 ...
The nuclear powered steam generator started as a power plant for the first nuclear submarine, the USS Nautilus. It was designed and built by the Westinghouse Electric Company power company for the submarine; from there the company started its development and research of nuclear-powered steam generators. [3]
Combined-cycle systems can reach higher values. As with all heat engines, their efficiency is limited, and governed by the laws of thermodynamics. The Carnot efficiency dictates that higher efficiencies can be attained by increasing the temperature of the steam. Sub-critical pressure fossil fuel power stations can achieve 36–40% efficiency.
The efficiency of a conventional steam–electric power plant, defined as energy produced by the plant divided by the heating value of the fuel consumed by it, is typically 33 to 48%, limited as all heat engines are by the laws of thermodynamics (See: Carnot cycle). The rest of the energy must leave the plant in the form of heat.
The energy requirements can be calculated from steam tables. For example, to heat water from 25 °C to steam at 250 °C at 1 atm requires 2869 kJ/kg. To heat water at 25 °C to liquid water at 250 °C at 5 MPa requires only 976 kJ/kg. It is also possible to recover much of the heat (say 75%) from superheated water, and therefore energy use for ...
The essential service water system (ESWS) circulates the water that cools the plant's heat exchangers and other components before dissipating the heat into the environment. Because this includes cooling the systems that remove decay heat from both the primary system and the spent fuel rod cooling ponds, the ESWS is a safety-critical system. [ 7 ]
The water required to cool the condenser is taken from a nearby river or ocean. It is then pumped back into the river or ocean, in warmed condition. The heat can also be dissipated via a cooling tower into the atmosphere. The United States uses LWR reactors for electric power production, in comparison to the heavy water reactors used in Canada ...