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Nuclear Power Plant Layout and Operation

➢ Introduction to Nuclear Power

A nuclear reactor produces electricity in much the same way other power plants do.  Some form of energy creates heat, which turns convert water into steam.  The pressure of the steam turns a generator, which produces electricity.

The difference is in how the heat is created. Power plants that run on fossil fuels burn coal, oil or natural gas to generate heat.  In a nuclear energy  heat is produced from splitting atoms – a process called nuclear fission-A process that continuously splits the nuclei of uranium atoms. This process produces a lot of energy, radiation, and very high heat.

1. nuclear reactor creates heat that is used to make steam

2. the steam turns a turbine connected to an electromagnet, called a generator

3. the generator produces electricity

➢ Working cycle of Nuclear Power Plant

Nuclear fission → water heats to produce steam → Steam turns turbines → turbines spin generators → generate electrical power

➢ Parts of Nuclear Power Plant

A Nuclear Reactor mainly consists of

a) Fuel      

b) Moderators           

c) Control rods            

d) Shielding       

e) Coolant     

f) Turbines    

g) Generator     

h) Cooler Pipes      

i) Water Supply

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Fuel: The fissionable material used in the reactor is called as fuel. The commonly used fuels are Uranium, Plutonium or Thorium. It can be U-235, U-238, Pu-236 or Th-232. Uranium is mostly preferred as it has high melting point. Following the enrichment process, uranium becomes a very concentrated fuel.

Moderators: Only neutrons of a fairly low speed should be used to have controlled chain reaction. To slow down the speed fast moving neutrons produced during the fission process, moderators are used. Moderator reduces the speed of the neutron by absorbing its energy but not absorb neutron. Graphite, Heavy water and Beryllium are common moderators.

Control Rods: These rods absorb neutrons and stop the chain reaction to proceed further. These are made up of steel containing a high percentage of material like cadmium or boron which can absorb neutrons. When control rods are completely inserted into the moderator block then all the neutrons is absorbed and reaction comes to halt.

Shielding: Shielding prevents radiations to reach outside the reactor. Lead blocks and concrete enclosure that is strong enough of several meters thickness are used for shielding. 

Containment – Nuclear reactors are encased in heavily reinforced concrete structures to prevent radioactivity from escaping into the atmosphere.

Coolant: The coolant is substance in a pipe to the steam generator where water is boiled. This is where heat-exchange process occurs. Heat is absorbed by the coolant that is produced in the reactor. Typical coolants are water, carbon dioxide gas or liquid sodium. 

Turbines: Steam produced in the boiler is now passes to a turbine. The force of the steam jet causes the turbine to rotate. Heat energy (steam) is converted to mechanical energy (moving turbine). 

Generator: The generator consists of coils that change the mechanical energy into electric energy. The turbine moves and the change in magnetic flux cause electricity. This is transmitted to substations for distribution of electric power.  

➢ Different types of reactors used in Nuclear power plants are:

1] Pressurised Water Reactor (PWR)

2] Boiling Water Reactor (BWR)

3] Pressurised Heavy Water Reactor (PHWR)

4] Advanced Gas-cooled Reactor (AGR)

5] Light water graphite-moderated reactor

6] Fast neutron reactors (FNR)

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➢ Advantages of Nuclear Power

1. The nuclear power plants produce energy without the emission of poisonous gases like carbon dioxide, sulfur dioxide etc. This is definitely good method to produce energy compare to other methods like burning of fossil fuels.

2. Nuclear power is an efficient method than coal based nuclear power process. As the uranium is used to produce energy which produces 20000 times more power than coal.

3. The nuclear waste is confined and small in amount than fossil fuels waste.

4. All the waste produce in the nuclear power are stored in fire, water or in capsules of earthquake for safety. The waste decays within period of time and don’t have any harmful effect on eco system. The nuclear waste is not like the chemical waste which does not decompose and emits poisonous gases. So the nuclear power is a good, eco friendly.

5. The nuclear power source is reliable and safe source of power.

➢ Disadvantage of Nuclear Power

1. Radioactive Waste: The waste produced by nuclear reactors needs to be disposed off at a safe place since they are extremely hazardous and can leak radiations if not stored properly. Such kind of waste emits radiations from tens to hundreds of years. The storage of radioactive waste has been major bottleneck for the expansion of nuclear programs.

2. Nuclear Accidents: Even small radiation leaks can cause devastating effects.People who work at nuclear power plants and live near those areas are at high risk of facing nuclear radiations, if it happens.

3. High Cost: Another practical disadvantage of using nuclear energy is that it needs a lot of investment to set up a nuclear power station.

4. Fuel Availability: Unlike fossil fuels which are available to most of the countries, uranium is very scare resource and exist in only few of the countries. Permissions of several international authorities are required before someone can even thought of building a nuclear power plant.

Nuclear power plants of India

There are six power plants in India. In those power plants, there are 20 nuclear reactors which produce 4,780MW electricity. These are operated by Nuclear Power Corporation of India Limited (NPCIL).

List of Nuclear Power Plants in India and their Capacity

|Plant |Location |State |Capacity |

|Narora Atomic Power Station |Narora |Uttar Pradesh |440  MW |

|Rajasthan Atomic Power Station |Rawatbhata |Rajasthan |1180  MW |

|Tarapur Atomic Power Station |Tarapur |Maharashtra |1400  MW |

|Kakrapar Atomic Power Station |Kakrapar |Gujarat |440  MW |

|Madras Atomic Power Station |Kalpakkam |Tamilnadu |440 MW |

|Kaiga Nuclear Power Plant |Kaiga |Karnataka |880  MW |

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