Nuclear power plant

Nuclear power plant:

      A nuclear power plant is converted atomic energy into electrical energy. The atomic energy is stored in radioactive fuel like Uranium, Thorium. In a nuclear power plant, atomic energy is transferred into thermal (heat) energy and the water are converted into the steam. After that working is same as the thermal power plant. Difference between the thermal power plant and nuclear power plant is the way to generate heat energy and fuel. In a thermal power plant, Coal is used as fuel and in a nuclear power plant, Uranium is used as a fuel. By nuclear power plant, around 10% of total electrical energy is generated.

          In a nuclear power plant, heat is generated by nuclear fission. The radioactive elements are used in this process. Generally, Uranium (U235) and Thorium (Th232) is used as fuel in a nuclear power plant. The fission of 1 kg uranium produces heat which is equal to heat produced by 4500 tons of high-grade coal. So, the big challenge is to control the amount of heat produced by fission in a nuclear reactor. This large amount of heat is transferred to the reactor coolant. For coolant, water, gas, or liquid metal is used. The high-temperature coolant is used to convert water into steam. But, the coolant contains a small amount of radioactive element. That’s why heat exchanger is used to transferring heat from coolant to water. The heat exchanger is used to transfer heat without getting a direct touch. This high-temperature steam is used to rotate the steam turbine. The alternator and steam turbine are connected to the same shaft and generates electrical energy.

Components of Nuclear power plant:

1) Nuclear Reactor: In a nuclear reactor, atomic energy is converted into thermal energy. The heat is produced in the nuclear reactor. This heat is produced by the fission process of a radioactive element. A large amount of heat is generated by the fission. This heat is transferred to the coolant. Two types of nuclear reactors are available. First is Pressurised water reactor (PWR). In this type of reactor, the produced heat is transferred to coolant with the help of heat exchanger. So, in this case, radioactive element and coolant cannot come in direct contact. But, in case of Boiling water reactor (BWR), the heat exchanger is not used and heat is transferred directly to the coolant. In this case, some amount of radioactive element come in contact with the steam (from heat) and it may get damage turbine blade.

2) Heat exchanger: Heat exchanger is used for transferring heat from one medium to another medium. In a nuclear power plant, the heat exchanger is used to transfers heat from the coolant to the water. In Boling water reactor, the heat exchanger is not used.

3) Coolant: Coolant is used to transfer heat. The water, heavy water, gas (CO2, helium), liquid metal (Na) are used as a coolant. The coolant is transferred a large amount of heat from reactors and keep reactor at a safe temperature. Coolant must be non-corrosive, high chemical and radiation stability, non-toxic, non-oxidising and it must not absorb neutrons.

4) Steam turbine: High-temperature and high-pressure steam are passed to the turbine. In a steam turbine, thermal energy is converted into kinetic energy.

5) Alternator: Alternator and steam turbine both are connected to the same shaft. So, alternator rotates at the speed of the turbine. In an alternator, kinetic energy is converted into electrical energy.

Advantages:

1) It requires less space compared to another power plant.

2) It requires a very small quantity of fuel. So, fuel transportation cost is less.

3) It does not require a large amount of water.

4) It is not affected by weather conditions.

5) Less manpower is required compared to the thermal power plant.

Disadvantages:

1) It requires well-trained operators.

2) It is not suitable for varying load conditions.

3) Very high initial cost.

4) It has an adverse effect on the health of population surrounding of the plant if radioactive 

waste is not carefully disposed of.