When a neutron is captured by a nucleus of an atom of U235 it splits up roughly into 2 equal fragments and about 2.5 neutrons are released and a large amount of energy (nearly 200 MeV) is produced. This is called fission process.
The neutrons so produced are fast moving neutrons and can be made to fission with other nuclei of U, thus establishing a chain reaction to take place.
When large number of fission occurs, enormous amount of heat is produced. This heat energy is converted into electrical energy in a nuclear powerplant.
Introduction to Nuclear Power Plant
Nuclear power plant uses uranium or thorium as its fuel for combustion. It has been found that the heat energy produced by fission reaction of 1 kg of uranium is equal to the heat produced by burning 4500 tonnes of coal In Figure 4.5, Nuclear reaction is illustrated
Nuclear Power Plants in India The first nuclear power plant commissioned in India is at Tarapur. The other nuclear power plants are at
- Rana Pratap Sagar in Rajastan
- Kalpakkam in chennai
- Narora in Uttar Pradesh
- Kakarpur near Surat at Gujarat.
- Kaiga power plant at Karnataka
A nuclear reactor is an apparatus in which heat is produced due to nuclear fission chain reaction
Functions of various parts of a nuclear reactor is
In the chain reaction, the neutrons produced are fast moving neutrons They are less effective in causing fission of U and try to escape from the reactor To improve the utilization of these fast neutrons, their speed is reduced in this moderator
2) Control Rods
The energy produced in the reactor during chain reaction is enormous. If this is not controlled properly entire core and structure may melt and radioactive rays may come out of the reactor. The control rods do this control
The neutrons produced during the fission process will be partly absorbed in the tor and balance neutrons will try to escape. Such escape of neutrons (losses) is pre reac vented by the reflector, which will send the neutrons back into the core. The returned neutrons can cause more fission..
4) Biological Shielding
During fission reaction alpha particles, beta particles, gamma rays and neutrons are produced. These radioactive rays are harmful to operating men. To protect from such harmful effects, thick concrete shielding is provided all round the reactor.
Coolant flows through and around the reactor core. It is used to obsorb large amount of heat produced in the reactor. If the coolant used is water, it absorbs the heat and gets converted into steam in the reactor, which is directly sent to turbine..
Main Components of a Nuclear Power Plant
The main components of a nuclear plant. These include nuclear reactor, heat exchanger (steam generator), turbine, electric generator and condenser.
Working of the Nuclear Power Plant
The heat generated in the reactor due to the fission reaction of the fuel is taken up by the coolant. The hot coolant then leaves the reactor and flows through the steam generator. In the steam generator, the hot coolant transfers its heat to the feed water which gets converted into steam. The steam produced is passed through the turbine, which is coupled with generator. Hence power is produced during running of the turbine.
The exhaust steam from the turbine is condensed in the condenser. The condensate then flows to steam generator through the feed pump. The cycle is thus repeated.
Advantages of Nuclear Power Plant
- Requires less space compared to steam power plant.
- Fuel required is negligible compared to coal requirement in steam power plant
- Fuel transport cost is less.
- Reliable in operation.
- Cost of erection is less.
- Water required is very less.
- Initial cost is higher.
- Not suitable for varying load condition.
- Radioactive wastes are hazardous. Hence these are to be handled with much care. Otherwise, it will affect the living organisms.
- Maintenance cost is higher.
- Trained Workers/Engineers are required to handle the operation.
See More: Diesel Power Plant
See More: Gas Turbine Power Plant
See More: Steam Power Plant