Nuclear Power Plant: Introduction, Components And Working Principle

In this article, I will share with you the introduction, components and working principle of a nuclear power plant.


You will get to understand why the nuclear power plant came into use.



The nuclear power plant is becoming one of the most dependable energy sources in most countries because of its efficiency.


People prefer using it because of the power demands it can meet without a hassle.


Without wasting time, let me share with you some of the reasons nuclear energy goes in favour over other power plants e.g. hydro-electric power and steam power plants.


The things needed to start a nuclear power plant aren’t that expensive compared to other power plants.


But the initial cost is kind of high once it’s started it can go on easily.


In a nuclear power plant, the only thing you need most is the supply of adequate water. The other needs like fuel, transportation network and a large storage facility are things you won’t need.


The world’s first nuclear power plant was commissioned in 1954 in U.S.S.R


After, the first nuclear power plant was commissioned the nuclear power plants keep on growing as each day a new technology emerges that keeps making the nuclear power plants more efficient.


Nuclear power plants need a large quantity of energy produced with a very small amount of fuel.


Nuclear power plants mainly produce electricity by giving out the heat that is used to convert water into steam, and the steam is fed into a steam turbine that is driven to produce the electricity via the generator.


I will explain more about the process that a nuclear power plant undergoes to produce electricity.


For now, this is what you should have in your mind about the nuclear power plant.



Fission process – this is a process that involves the splitting of Uranium-235 (U235) into equal fragments after it captures the neutrons, which results in a large amount of energy produced.


Fertile material – this is a material that absorbs neutrons and undergoes a change to form fissionable material, e.g. U238 and Th232.


Chain reaction – this is a reaction that comes as a result of fast-moving neutrons fission with the nuclei of U235.


Secondary fuel – this is a fissionable material that is formed because of Thorium combining with neutrons to form U233 (Th232+Neutrons—> U233).


Plutonium-239 (Pu239)this is a fissionable material produced after a chain reaction of Uranium-238 and Neutrons (U238+Neutron —> Pu239).


Unit of radioactivity – it’s the rate of decay of one gram of radioactivity element radium.


Nuclear fuel – it’s an element whose nuclei can undergo nuclear fission by nuclear bombardment and produce a fission chain reaction, e.g. U233, U239 and Pu239.


Moderating ratio – it’s the ratio of the power of a moderator to slow down neutrons to the macroscopic neutron capture coefficient.


Neutron flux – it’s the measure of neutron’s radiation intensity that can pass through 1cm2 in a second.


Conservation ratio – it’s the ratio of the number of secondary fuel atoms to the number of consumed primary fuel atoms.


Breeder reactor – it’s a reactor that has a conservation ratio above unity.


Converter reactor – it’s a reactor that produces fissionable material equal to or less than the consumed ones.


Reactor core – it’s the centre of the reactor where the fission process takes place.


Primary coolant – this is the first coolant that transfers heat from the reactor core.


Secondary coolant – it’s the second coolant that takes heat from the primary coolant and transfers it to the steam turbine via the pipes or tubes.


Main components of a nuclear power plant.

For you to understand how the nuclear power plant works you have to know the components and their functions.


These are the main components of a nuclear power plant;

  1. Nuclear reactor.
  2. Heat exchanger.
  3. Turbine.
  4. Electric generator.
  5. Condenser.


1. Nuclear reactor.

A nuclear reactor is an apparatus in which nuclear fission takes place and a large quantity of heat is produced.


This is the core of the nuclear power plant since without the heat from the nuclear reactor there is no way electricity will be produced.


A nuclear reactor has the following parts;

  1. Reflector.
  2. Moderator.
  3. Control rods.
  4. Concrete shielding or biological shielding.
  5. Pressure vessel.
  6. Coolant.


Reflector – reflector is used to prevent neutrons from escaping from the reactor core.


Just like any other energy production process, there will always be a part of the energy that will escape into the atmosphere.


During nuclear fission, some neutrons will try to escape from the reactor and it will be the work of the reflector to send the neutrons back to the reactor core.


The reflector is made up of graphite and beryllium.


Moderator – a moderator is a material that reduces the speed of the fast-moving neutrons that are produced during nuclear fission.


Moderator only slows down the fast-moving neutrons but it does not absorb them.


It reduces the speed of these fast-moving neutrons by scattering them.


In most cases, graphite, heavy water and beryllium are generally used as moderators.


For any material to be used as a moderator it should possess the following properties;

  1. It should have a higher thermal conductivity to be able to withstand the amount of heat produced during nuclear fission.
  2. The material selected to be used as a moderator should be available in large quantities and pure form.
  3. If it’s a solid material that is to be used as a moderator then it should have a high melting point, if it’s a liquid then it should have a high boiling point.
  4. The material used as a moderator should be corrosion-resistant.
  5. The material used as a moderator should be stable under a large amount of heat and radiation.
  6. The material used as a moderator should be able to slow the neutrons down without absorbing them.


Control rods – control the nuclear reaction by absorbing the neutrons in the reactor core.


They are cylindrical and are made up of either boron or cadmium


They can increase the power of nuclear fission or decrease them by insertion and withdrawal.


When they are inserted deep they absorb more neutrons and damp down the reaction and when they are withdrawn they absorb fewer neutrons.


These control rods are essential when it comes to shutting down the nuclear reaction in case there is a problem.


The insertion and withdrawal can be done manually or automatically.


Concrete shielding or biological shielding – this shielding is used to protect the operators from possible radiation hazards.


Thick layers of lead or concrete are laid around the reactor to act as a shield.


The thick layers of lead or concrete prevent gamma rays and neutrons from getting out of the reactor.


Gamma rays are very dangerous to human health.


Thick layers of metal or plastics are used to stop the alpha and beta particles produced during nuclear fission.


All these, gamma rays and alpha and beta particles are produced during nuclear fission.


Pressure vessel – it’s a strong-walled vessel that contains the components of the reactor and houses the core of the power reactor.


This is the vessel that sustains and hold all the chain reaction taking place in the reactor core.


Coolant – it’s used to transfer heat energy that is produced during nuclear fission in the reactor.


The coolants can be in liquid, liquid metals or gas.


Examples of liquid coolants are; water (light or heavy water).

The gaseous coolants include; air, carbon dioxide, hydrogen and helium.

The liquid metals are; sodium and a mixture of sodium and potassium, inorganic and organic fluid.


2. Heat exchanger.

The heat exchanger is used to transfer heat energy from the primary coolant to the secondary coolant.


3. Turbine.

This is the machine that uses the steam to run and transform the steam energy into electricity via the generator.


4. Electric generator.

The electric generator is used to provide the electricity from the turbine.


5. Condenser.

The main function of the condenser is to condense the exhaust steam from the turbine to make it efficient. The condensed steam flows to the feed pump where it’s again returned to the reactor to absorb more heat.


Working principle of the nuclear power plant.

Energy in nuclear fission is produced by Uranium and Plutonium. This reaction produces a large amount of heat that is used to heat water to generate steam which is used for running the generator to produce electricity.


In the reactor, neutrons are captured by a nucleus of an atom of U235 since it’s the most unstable isotope of Uranium, it splits up roughly into two equal fragments and about 2.5 fast-moving neutrons are produced.


The first moving neutrons can be made to fission with other nuclei of U235 which enable a chain reaction to take place thus sustaining the reaction and producing a large amount of heat needed.


This kind of reaction of nuclei with fast-moving neutrons happens in fast reactors.


The other case can be that the fast-moving neutrons can be slowed down by the moderator to bring about smooth fission, this reaction takes place in thermal reactors.


The neutron can produce energy in, either way, be it fast, slow or intermediate, this mostly depends on the kind of reactor used in the nuclear power plant.


Even when the neutrons are slowing down they can still produce the amount of energy needed, this mostly happens in intermediate reactors.


So, the fission between the neutrons and the fuel results in the production of large amount of heat, the chain reaction will continue as long as the neutron liberated by fission balances the disposal of neutrons in the following ways;

  • There is an escape of neutrons from the fissionable material.
  • The fission process captures U235, Pu239 and U233.
  • Non-fission capture by control rods and moderator, e.t.c.


Note that, not all neutrons are used in the production of energy, out of 2.5 one neutron is used to sustain the chain reaction, 0.9 are captured by U238 which gets converted to fissionable material Pu239 and about 0.6 neutrons are partially absorbed by the reactor component while some escape from the reactor.


The most important thing that enables the production of energy is the fission process.


Without this process, there is no way the energy will be produced.


This is just an overview of how nuclear power plant produces electricity but there is more when it comes to the types of reactors used in these plants.


You might like this: Different Types Of Nuclear Reactors & Working Principles


That will be a topic on its own.


Thanks for reading, if you have any questions or a point to add leave your comment in the comment section.


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