Nuclear Reactor - Nuclear reactor is the main part of the nuclear power plant. In a nuclear reactor, the main chain reaction takes place and generates a huge amount of heat energy. The generated heat energy in this part is used to generate steam and run the turbine. The nuclear power plants use the nuclear fission process in which heavy atomic weight material i.e atom of uranium or other similar radioactive materials nucleus splits into the metal of lower atomic weight and release a huge amount of energy. This huge amount of energy is used in converting water into steam and this generated steam is utilized in driving a steam turbine coupled to a generator. Nuclear reactor are classified into the following categories
- Advanced gas-cooled reactor(AGR)
- Magnox Reactor
- Pressurized Water Reactor
- Boiling water Reactor
- Liquid Metal Fuelled Reactor
- Fast Breeder Reactor
Advanced Gas Cooled Reactor
In the advanced gas-cooled reactor, uranium dioxide is used as fuel. The coolant is carbon dioxide which passes through the heat exchanger and raises steam and graphite is used as a moderator. The reactor can be refueled on load and this is an operational advantage. A gas-cooled reactor is economical when the load factor is more than 70 %The overall efficiency of this reactor is about 40%. The systematic diagram of the advanced gas-cooled reactor is given below.
Magnox Reactor
In this reactor natural uranium is used as fuel.it is also a gas cooled reactor and similar to advanced cooled reactor.Carbon dioxide is used as coolant in this reactor. and graphite is used as moderator.In this reactor the fuel element is connected in a special magnesium alloy which is called magnox.The overall efficiency of this reactor is about 30%
Pressurized Water Reactor
In this nuclear reactor enriched uranium oxide is used as fuel and pressurized water is used as both coolant and moderator.The overall efficiency is about 33%.The systematic diagram of pressurized water reactor is given below.
Boiling Water Reactor
In this reactor also enriched uranium oxide is used as fuel and normal water is used as coolant and moderator.it is cycle reactor.The steam is generated in the reactor itself and this steam after passing through turbine and condenser return to the reactor.the overall efficiency of this reactor is about 35%.
The systematic diagram of boiling water reactor is given below.
Liquid Metal Fuelled Reactor
As name suggest that,this reactor used liquied metal fuel i.e uranium in sodium (since it has excellent heat transfer properties so it permits high operating temperatures and ratings.In this reactor graphite is used as moderator and sodium is used as coolant.
Fast Breeder Reactor
A fast breeder reactor is different from the thermal reactor.A thermal reactor uses fissile nuclear fuel and produces heat energy.A fast breeder reactor produces heat and at the same time converts fertile material into fissile material.it is possible to make a fast reactor to produce more fissionable material that it consumes. In a fast breeder reactor, uranium-238 can be converted into Pullonium-239 or thorium-232 into uranium-233.
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