Component of Nuclear reactor -Nuclear reactor is the heart of nuclear power plant.In nuclear power plant,nuclear chain reaction takes place and due this chain reaction huge amount of heat energy is generate.This generated heat energy is used to generate steam and this generated steam is send to theb turbine and in turbine the steam move the alternator.Nuclear reactor is the combination of different type of component and these components are
- Moderator
- Control Rod
- Coolant
- Fuel
Moderator
The purpose of moderator material is to reduce the kinetic energy of the fast moving neutron.the fast moving neutron collide with the nuclei of moderator material and loose its kinetic energy and get slowed down.the material which is used as moderator possess the following given properties
- The material should be chemically inert and should not corrode
- The material should be inexpensive
- The material should not react with neutrons because if the neutron will captured by the moderator material then nuclear chain reaction will be lost and it will reduce the total efficiency of the power plant.
- The material should not undergo harmful physical or chemical changes when bombared by neutrons.
- the average neutron necleus collision should lead to large neutron energy loss.
Out of the element having small atomic mass ,gases are unsuitable on account of its low density and the consequent small number of collisions.Helium and beryllium are costly.Boron and lithium have high neutron absorption tendency.heavy water is an ideal moderator material and used in many reactor in spite of its high cost.
Control Rod
The control rods in nuclear reactor are used to initiate the chain reaction and to maintain a steady state value during the operation of the reactor, also reactor may be able to shutdown automatically under emergency condition.Material used for control rod should have high absorption capacity for neutrons.The most common used material for control rod is cadmium boron and helium.
Coolant
Coolant are used to remove the generated heat energy from the fuel elements and transfer it to water.A good coolant should not
- absorbs neutrons
- be non-oxidising
- non-toxic
- and non corrosive
- and have high chemical and radiation stability
- have good heat transfer capability
The material used as coolants are carbon dioxide,liquid metal,water and heavy water.
Fuel
In nuclear power plant ,radioactive substance are used as fuel.In most of nuclear power plant Uranium-235 and Pulonium-239 are used as fuel.The natural uranium contains 99.23% of uranium-238and remaining uranium-235.The nuclear fission processes is used in nuclear power plant.for generation of heat energy.In nuclear fission process an atom of heavy element is bombarded by a slow moving neutron split into lighter element and gives large amount of energy.
