Pressurized Water Reactor (PWR):Pumps for nuclear power plant

[ Nuclear Power Generation ]

[ ENERGY ]

Pump for continuous re-circulation of nuclear furnace coolant (light water) to the steam generator to cool the thermal energy generated by the nuclear power

At the time of the trouble of the primary cooling water loss or when the main steam pipe is broken, the reactor core is urgently cooled and boric acid is urgently injected. As a result, the reactor core is cooled and the fuel rod is kept in the allowable temperature.

This pump supplies make-up water to maintain the volume when the primary reactor coolant has contracted due to decrease of load. Also it supplies sealing water to the sealed part of the primary reactor coolant pump.

This pump removes the heat of the primary reactor coolant after the reactor is stopped and lowers its temperature. Also, it prevents expansion of the trouble at the time of the trouble of the coolant loss by injecting boric acid of the fuel replacement water pump into the reactor core.

This pump has the role of minimizing the leakage of the radioactive material from the containment vessel at the time of the accident of nuclear power. At the time of such accident the pump sprays boric acid water into the vessel and eliminate contamination of the fissionable material.

This pump has the intermediate characteristics of two lines, the primary reactor coolant and the seawater pump, and even if the primary reactor coolant leaks, it prevents radioactive water from being discharged outside.

This pump sends water to each of the following equipment and cools them.

• Nuclear reactor component cooler
• Diesel generator
• Refrigerating machine for air-conditioning
• Supply of seawater pump bearing lubricating water and cooling of the electric motor bearing

This is the horizontal type turbine driven pump for sending water of the condensing tank (or the deaerator storage tank) to the steam generator to remove the heat of nuclear reactor cooling line when starting or stopping. Since it is necessary to supply feed water even when electricity stops, two pumps are provided; one is the motor driven pump that can be operated from the electric source of the diesel generator and the other is the turbine driven pump that can be operated with main steam.

This is the horizontal type turbine driven pump for sending water of the condensing tank (or the deaerator storage tank) to the steam generator to remove the heat of nuclear reactor cooling line when starting or stopping. Since it is necessary to supply feed water even when electricity stops, two pumps are provided; one is the motor driven pump that can be operated from the electric source of the diesel generator and the other is the turbine driven pump that can be operated with main steam.

This pump takes from the deaerator storage tank feed water pressured up by the booster pump and pushes it into the steam generator through the high-pressure heater. Accordingly, the main feed pump must be high temperature and high-pressure pump since it requires the head larger than the pressure inside the steam generator. Also, from the viewpoint of assuring feed water of the steam generator, this is one of the important auxiliary machinery of the plant.

This pump takes feed water from the deaerator storage tank and increases NPSHava (net positive suction head). Namely, the purpose of installation of this pump is to assist suction of the main feed water pump. In the case of the plant in which the deaerator is not installed, the feed water booster pump is not required and not installed since the head of the condensate pump is designed very high.

This booster takes condensate from the condenser hot well and sends it to the condensate booster pump through the grand condenser and the condensate demineralizer.

The purpose of installation of this pump is to pressure up the condensate sent from the condensate pump and to send it to the deaerator through the low-pressure heater. This pump is not installed in the plant in which the condensate demineralizer is not provided.

This pump is installed to suction seawater from the intake, to exchange heat while passing through the condenser and to discharge water to sea from the water discharge outlet. Usually two units are installed and there is no spare. It is determined from the viewpoint of the construction cost and economy whether the pump should be of the fixed pitch vane type or the variable pitch vane type.

This pump has the hydraulic variable pitch vane structure. Its merits are smaller consumption of motive power and smooth start of operation (start of operation with the vane fully closed). Whether the pump should be of the fixed pitch vane type or the variable pitch vane type is determined from the viewpoint of construction cost and economy.

Pump with the fixed impeller

The steam discharged from the high-pressure turbine is condensed to drain. Drain, after collected in the drain tank, is sent to the deaerator by the moisture separator drain pump.