A nuclear power plant uses the energy released due to nuclear reactions. The nuclear reaction is a chain reaction. The rate of reaction increases continuously in an uncollected manner if a proper arrangement is not taken to control the reaction. In actual nuclear reaction, uranium is bombarded with slow moving neutrons. These neutrons are called fission neutrons. This bombarding breaks uranium atom nucleus and releases energy.
From above few lines it is clear that to facilitate a nuclear reaction we need four basic arrangements.
- A vessel where the reaction will occur that is reaction chamber.
- The raw material for the reaction that is uranium.
- The arrangement for decelerating motion of fission neutrons before bombarding that is graphite.
- The reaction controlling arrangement something which can highly absorb neutrons that is cadmium.
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A basic construction of nuclear reactor consists of these four primary arrangements. In the reaction chamber in the vessel uranium rods are kept inside graphite cylinder. As we have already come to know that graphite decelerates the speed of the neutrons before these strike on the uranium rods. To control the rate of reaction cadmium rods are inserted in the vessel from the top. Cadmium is a high absorber of neutrons. When the cadmium rods inserted deep in the vessel almost all of the neutrons will be absorbed by the cadmium hence reaction will stop again when it is needed to restart the reaction the rods are pulled out from the vessel. Although this movement of the control rods is not manual it is automatically controlled through microprocessor as per requirement.
The rate of release of energy through chain reaction or in other words the rate of chain reaction itself depends on the length of the inserted portion of cadmium rod in the reaction chamber of the nuclear reactor. The enclosure in which the nuclear reaction occurs is called reaction chamber. The reaction chamber is physically filled with coolant. Normally liquid sodium metal is used as a coolant. The hot coolant is taken to the heat exchanger through the pipeline, and after releasing heat to the water inside the heat exchanger, the coolant is taken back to the reaction chamber with the help of a pump called coolant circulating pump. The water stored in the heat exchanger absorbs heat from the coolant and becomes steam.
The steam ultimately rotates a steam turbine, and after that mechanical work, it is condensed by using condenser and feedback to the heat exchanger through feed water pump. The alternator is attached to the steam turbine converts mechanical energy into electrical energy. This is how a nuclear power station works. So we have come to know that the only typical arrangement in a nuclear power plant is that nuclear reactor except this nuclear reactor other arrangements are basically just like other conventional thermal power plants.