A nuclear power plant is a thermal power station where nuclear fuel is used to generate the heat which converts water into steam. This steam is further used to run the turbine. This turbine is connected to an alternator which converts mechanical energy of turbine into electrical energy. It works on Rankine cycle.
Working of Nuclear Power Plant
A nuclear power plant is basically composed of three main elements which are fuel rods, control rods and moderator. In a nuclear reaction fuel atom gets bombarded with neutron. This process splits the atom into two atoms, with a large amount of heat generation. These processes causing a chain reaction. This chain reaction is controlled with control rods.
Control rods are used to absorb excess neutrons generated during fission process. Otherwise the fission process will become uncontrollable and reactor will melt down.
Types of nuclear reactors
- Boiling water reactor (BWR)
- Pressurized water reactor (PWR)
- Pressurized heavy water reactor (PHWR or CANDU)
- Gas cooled reactor
- Fast neutron reactor
- Light water graphite reactor
Boiling water reactor (BWR)
Pressurized water reactor
The water which carries away heat from reactor transfers its heat to water driving turbine through a heat exchanger. The water which carries heat from the reactor is pressurized so that it does not convert to steam. This type of reactor uses Uranium (235) with 3% to 4.5% enrichment.
Pressurized heavy water reactor
Given type of reactor is same as pressurized water reactor, the only difference is that it uses heavy water as moderator and coolant. This heavy water is a good moderator like normal water but has very poor ability to absorb neutrons. It means we have a greater number of thermal neutrons to continue the fission process. Which ultimately gives us freedom to use Uranium (235) at its natural concentration i.e. 0.7%.
The two common nuclear fuels are Uranium (235) and Plutonium (239). Uranium is a heavy metal and is present in a very huge quantity on earth. It has two isotopes Uranium (238) and Uranium (235). Isotopes are atoms of same element with a different number of neutrons.
Only Uranium (235) can be used for fission process and it is only 0.7% of total Uranium available. The process of obtaining, refining and using nuclear fuel is known as nuclear fuel cycle.
Advantages of nuclear energy
- It produces less air pollution compared to fossil fuel-based power plant
- Its fuel is abundant on earth
- Its fuel is cheap
- Its fuel has very high energy density
Disadvantages of nuclear energy
- Its waste is radioactive and is dangerous to environment and human life
- Any failure of nuclear power plant can cause a disaster
- Capital investment and infrastructure cost is very high