Nuclear Power Station | Power Systems - Electrical Engineering (EE) PDF Download

 Page 1


  
 
A generating station in which nuclear energy is converted into electrical energy is known as a nuclear 
power station. 
In nuclear power station, heavy elements such as Uranium (U ) or Thorium (Th ) are subjected to 
nuclear fission  in a special apparatus known as a reactor. The heat energy thus released is utilized in 
raising steam at high temperature and pressure. The steam runs the steam turbine which converts steam 
energy into mechanical energy. The turbine drives the alternator which converts mechanical energy into 
electrical energy. 
The most important feature of a nuclear power station is that huge amount of electrical energy 
can be produced from a relatively small amount of nuclear fuel as compared to other conventional types 
of power stations. It has been found that complete fission of 1 kg of Uranium (U ) can produce as much 
energy as can be produced by the burning of 4,500 tons of high grade coal. Although the recovery of 
principal nuclear fuels (i.e., Uranium and Thorium) is difficult and expensive, yet the total energy content 
of the estimated world reserves of these fuels are considerably higher than those of conv entional fuels, 
viz., coal, oil and gas. At present, energy crisis is gripping us and, therefore, nuclear energy can be 
successfully employed for producing low cost electrical energy on a large scale to meet the growing 
commercial and industrial demands. 
 
Advantages: 
 
I. The amount of fuel required is quite small. Therefore, there is a considerable saving in the cost of 
fuel transportation. 
II. A nuclear power plant requires less space as compared to any other type of the same size. 
III. It has low running charges as a small amount of fuel is used for producing bulk electrical energy. 
IV. This type of plant is very economical for producing bulk electric power. 
V. It can be located near the load centers because it does not require large quantities of water  and 
need not be near coal mines. Therefore, the cost of primary distribution is reduced. 
VI. There are large deposits of nuclear fuels available all over the world. Therefore, such plants can 
ensure continued supply of electrical energy for thousands of years. 
VII. It ensures reliability of operation. 
 
Disadvantages: 
 
I. The fuel used is expensive and is difficult to recover. 
Page 2


  
 
A generating station in which nuclear energy is converted into electrical energy is known as a nuclear 
power station. 
In nuclear power station, heavy elements such as Uranium (U ) or Thorium (Th ) are subjected to 
nuclear fission  in a special apparatus known as a reactor. The heat energy thus released is utilized in 
raising steam at high temperature and pressure. The steam runs the steam turbine which converts steam 
energy into mechanical energy. The turbine drives the alternator which converts mechanical energy into 
electrical energy. 
The most important feature of a nuclear power station is that huge amount of electrical energy 
can be produced from a relatively small amount of nuclear fuel as compared to other conventional types 
of power stations. It has been found that complete fission of 1 kg of Uranium (U ) can produce as much 
energy as can be produced by the burning of 4,500 tons of high grade coal. Although the recovery of 
principal nuclear fuels (i.e., Uranium and Thorium) is difficult and expensive, yet the total energy content 
of the estimated world reserves of these fuels are considerably higher than those of conv entional fuels, 
viz., coal, oil and gas. At present, energy crisis is gripping us and, therefore, nuclear energy can be 
successfully employed for producing low cost electrical energy on a large scale to meet the growing 
commercial and industrial demands. 
 
Advantages: 
 
I. The amount of fuel required is quite small. Therefore, there is a considerable saving in the cost of 
fuel transportation. 
II. A nuclear power plant requires less space as compared to any other type of the same size. 
III. It has low running charges as a small amount of fuel is used for producing bulk electrical energy. 
IV. This type of plant is very economical for producing bulk electric power. 
V. It can be located near the load centers because it does not require large quantities of water  and 
need not be near coal mines. Therefore, the cost of primary distribution is reduced. 
VI. There are large deposits of nuclear fuels available all over the world. Therefore, such plants can 
ensure continued supply of electrical energy for thousands of years. 
VII. It ensures reliability of operation. 
 
Disadvantages: 
 
I. The fuel used is expensive and is difficult to recover. 
II. The capital cost on a nuclear plant is very high as compared to other types of plants. 
III. The erection and commissioning of the plant requires greater technical know-how. 
IV. The fission by-products are generally radioactive and may cause a dangerous amount of 
radioactive pollution. 
V. Maintenance charges are high due to lack of standardization. Moreover, high salaries of specially 
trained personnel employed to handle the plant further raise the cost. 
VI. Nuclear power plants are not well suited for varying loads as the reactor does not respond to the 
load fluctuations efficiently. 
VII. The disposal of the by-products, which are radioactive, is a big problem. They have either to be 
disposed off in a deep trench or in a sea away from sea-shore. 
 
Schematic Arrangement of Nuclear Power Station: 
  
The schematic arrangement of a nuclear power station is shown in Fig; the whole arrangement can be 
divided into the following main stages: 
(i) Nuclear reactor 
(ii) Heat exchanger 
(iii) Steam turbine 
(iv) Alternator. 
 
 
Page 3


  
 
A generating station in which nuclear energy is converted into electrical energy is known as a nuclear 
power station. 
In nuclear power station, heavy elements such as Uranium (U ) or Thorium (Th ) are subjected to 
nuclear fission  in a special apparatus known as a reactor. The heat energy thus released is utilized in 
raising steam at high temperature and pressure. The steam runs the steam turbine which converts steam 
energy into mechanical energy. The turbine drives the alternator which converts mechanical energy into 
electrical energy. 
The most important feature of a nuclear power station is that huge amount of electrical energy 
can be produced from a relatively small amount of nuclear fuel as compared to other conventional types 
of power stations. It has been found that complete fission of 1 kg of Uranium (U ) can produce as much 
energy as can be produced by the burning of 4,500 tons of high grade coal. Although the recovery of 
principal nuclear fuels (i.e., Uranium and Thorium) is difficult and expensive, yet the total energy content 
of the estimated world reserves of these fuels are considerably higher than those of conv entional fuels, 
viz., coal, oil and gas. At present, energy crisis is gripping us and, therefore, nuclear energy can be 
successfully employed for producing low cost electrical energy on a large scale to meet the growing 
commercial and industrial demands. 
 
Advantages: 
 
I. The amount of fuel required is quite small. Therefore, there is a considerable saving in the cost of 
fuel transportation. 
II. A nuclear power plant requires less space as compared to any other type of the same size. 
III. It has low running charges as a small amount of fuel is used for producing bulk electrical energy. 
IV. This type of plant is very economical for producing bulk electric power. 
V. It can be located near the load centers because it does not require large quantities of water  and 
need not be near coal mines. Therefore, the cost of primary distribution is reduced. 
VI. There are large deposits of nuclear fuels available all over the world. Therefore, such plants can 
ensure continued supply of electrical energy for thousands of years. 
VII. It ensures reliability of operation. 
 
Disadvantages: 
 
I. The fuel used is expensive and is difficult to recover. 
II. The capital cost on a nuclear plant is very high as compared to other types of plants. 
III. The erection and commissioning of the plant requires greater technical know-how. 
IV. The fission by-products are generally radioactive and may cause a dangerous amount of 
radioactive pollution. 
V. Maintenance charges are high due to lack of standardization. Moreover, high salaries of specially 
trained personnel employed to handle the plant further raise the cost. 
VI. Nuclear power plants are not well suited for varying loads as the reactor does not respond to the 
load fluctuations efficiently. 
VII. The disposal of the by-products, which are radioactive, is a big problem. They have either to be 
disposed off in a deep trench or in a sea away from sea-shore. 
 
Schematic Arrangement of Nuclear Power Station: 
  
The schematic arrangement of a nuclear power station is shown in Fig; the whole arrangement can be 
divided into the following main stages: 
(i) Nuclear reactor 
(ii) Heat exchanger 
(iii) Steam turbine 
(iv) Alternator. 
 
 
 
 
(i) Nuclear reactor. It is an apparatus in which nuclear fuel (U ) is subjected to nuclear     fission. It controls 
the chain reaction* that starts once the fission is done. If the chain     reaction is not controlled, the result 
will be an explosion due to the fast increase in the     energy released.     A nuclear reactor is a cylindrical 
stout pressure vessel and houses fuel rods of Uranium,     moderator and control rods (See Fig.) The fuel 
rods constitute the fission material and     release huge amount of energy when bombarded with slow 
moving neutrons. The moderator consists of graphite rods which enclose the fuel rods. The moderator 
slows down the neutrons before they bombard the fuel rods. The control rods are of cadmium and are 
inserted into the reactor. Cadmium is strong neutron absorber and thus regulates the supply of neutrons 
for fission. When the control rods are pushed in deep enough, they absorb most of fission neutrons and 
hence few are available for chain reaction which, therefore, stops.  However, as they are being 
Page 4


  
 
A generating station in which nuclear energy is converted into electrical energy is known as a nuclear 
power station. 
In nuclear power station, heavy elements such as Uranium (U ) or Thorium (Th ) are subjected to 
nuclear fission  in a special apparatus known as a reactor. The heat energy thus released is utilized in 
raising steam at high temperature and pressure. The steam runs the steam turbine which converts steam 
energy into mechanical energy. The turbine drives the alternator which converts mechanical energy into 
electrical energy. 
The most important feature of a nuclear power station is that huge amount of electrical energy 
can be produced from a relatively small amount of nuclear fuel as compared to other conventional types 
of power stations. It has been found that complete fission of 1 kg of Uranium (U ) can produce as much 
energy as can be produced by the burning of 4,500 tons of high grade coal. Although the recovery of 
principal nuclear fuels (i.e., Uranium and Thorium) is difficult and expensive, yet the total energy content 
of the estimated world reserves of these fuels are considerably higher than those of conv entional fuels, 
viz., coal, oil and gas. At present, energy crisis is gripping us and, therefore, nuclear energy can be 
successfully employed for producing low cost electrical energy on a large scale to meet the growing 
commercial and industrial demands. 
 
Advantages: 
 
I. The amount of fuel required is quite small. Therefore, there is a considerable saving in the cost of 
fuel transportation. 
II. A nuclear power plant requires less space as compared to any other type of the same size. 
III. It has low running charges as a small amount of fuel is used for producing bulk electrical energy. 
IV. This type of plant is very economical for producing bulk electric power. 
V. It can be located near the load centers because it does not require large quantities of water  and 
need not be near coal mines. Therefore, the cost of primary distribution is reduced. 
VI. There are large deposits of nuclear fuels available all over the world. Therefore, such plants can 
ensure continued supply of electrical energy for thousands of years. 
VII. It ensures reliability of operation. 
 
Disadvantages: 
 
I. The fuel used is expensive and is difficult to recover. 
II. The capital cost on a nuclear plant is very high as compared to other types of plants. 
III. The erection and commissioning of the plant requires greater technical know-how. 
IV. The fission by-products are generally radioactive and may cause a dangerous amount of 
radioactive pollution. 
V. Maintenance charges are high due to lack of standardization. Moreover, high salaries of specially 
trained personnel employed to handle the plant further raise the cost. 
VI. Nuclear power plants are not well suited for varying loads as the reactor does not respond to the 
load fluctuations efficiently. 
VII. The disposal of the by-products, which are radioactive, is a big problem. They have either to be 
disposed off in a deep trench or in a sea away from sea-shore. 
 
Schematic Arrangement of Nuclear Power Station: 
  
The schematic arrangement of a nuclear power station is shown in Fig; the whole arrangement can be 
divided into the following main stages: 
(i) Nuclear reactor 
(ii) Heat exchanger 
(iii) Steam turbine 
(iv) Alternator. 
 
 
 
 
(i) Nuclear reactor. It is an apparatus in which nuclear fuel (U ) is subjected to nuclear     fission. It controls 
the chain reaction* that starts once the fission is done. If the chain     reaction is not controlled, the result 
will be an explosion due to the fast increase in the     energy released.     A nuclear reactor is a cylindrical 
stout pressure vessel and houses fuel rods of Uranium,     moderator and control rods (See Fig.) The fuel 
rods constitute the fission material and     release huge amount of energy when bombarded with slow 
moving neutrons. The moderator consists of graphite rods which enclose the fuel rods. The moderator 
slows down the neutrons before they bombard the fuel rods. The control rods are of cadmium and are 
inserted into the reactor. Cadmium is strong neutron absorber and thus regulates the supply of neutrons 
for fission. When the control rods are pushed in deep enough, they absorb most of fission neutrons and 
hence few are available for chain reaction which, therefore, stops.  However, as they are being 
withdrawn, more and more of these fission neutrons cause fission and hence the intensity of chain 
reaction (or heat produced) is increased. Therefore, by pulling out the control rods, power of the nuclear 
reactor is increased, whereas by pushing them in, it is reduced. In actual practice, the lowering or raising 
of control rods is accomplished automatically according to the requirement of load. The heat produced in 
the reactor is removed by the coolant, generally a sodium metal. The coolant carries the heat to the   heat 
exchanger. 
 
 
 
 
(ii) Heat exchanger: The coolant gives up heat to the heat exchanger which is utilized in raising the steam. 
After giving up heat, the coolant is again fed to the reactor. 
(iii) Steam turbine: The steam produced in the heat exchanger is led to the steam turbine through a valve. 
After doing a useful work in the turbine, the steam is exhausted to condenser. The condenser condenses 
the steam which is fed to the heat exchanger through feed water pump. 
(iv) Alternator: The steam turbine drives the alternator which converts mechanical energy into electrical 
energy. The output from the alternator is delivered to the bus-bars through transformer, circuit breakers 
and isolators. 
 
Selection of Site for Nuclear Power Station: 
 
The following points should be kept in view while selecting the site for a nuclear power station: 
       (i) Availability of water. As sufficient water is required for cooling purposes, therefore, the 
Page 5


  
 
A generating station in which nuclear energy is converted into electrical energy is known as a nuclear 
power station. 
In nuclear power station, heavy elements such as Uranium (U ) or Thorium (Th ) are subjected to 
nuclear fission  in a special apparatus known as a reactor. The heat energy thus released is utilized in 
raising steam at high temperature and pressure. The steam runs the steam turbine which converts steam 
energy into mechanical energy. The turbine drives the alternator which converts mechanical energy into 
electrical energy. 
The most important feature of a nuclear power station is that huge amount of electrical energy 
can be produced from a relatively small amount of nuclear fuel as compared to other conventional types 
of power stations. It has been found that complete fission of 1 kg of Uranium (U ) can produce as much 
energy as can be produced by the burning of 4,500 tons of high grade coal. Although the recovery of 
principal nuclear fuels (i.e., Uranium and Thorium) is difficult and expensive, yet the total energy content 
of the estimated world reserves of these fuels are considerably higher than those of conv entional fuels, 
viz., coal, oil and gas. At present, energy crisis is gripping us and, therefore, nuclear energy can be 
successfully employed for producing low cost electrical energy on a large scale to meet the growing 
commercial and industrial demands. 
 
Advantages: 
 
I. The amount of fuel required is quite small. Therefore, there is a considerable saving in the cost of 
fuel transportation. 
II. A nuclear power plant requires less space as compared to any other type of the same size. 
III. It has low running charges as a small amount of fuel is used for producing bulk electrical energy. 
IV. This type of plant is very economical for producing bulk electric power. 
V. It can be located near the load centers because it does not require large quantities of water  and 
need not be near coal mines. Therefore, the cost of primary distribution is reduced. 
VI. There are large deposits of nuclear fuels available all over the world. Therefore, such plants can 
ensure continued supply of electrical energy for thousands of years. 
VII. It ensures reliability of operation. 
 
Disadvantages: 
 
I. The fuel used is expensive and is difficult to recover. 
II. The capital cost on a nuclear plant is very high as compared to other types of plants. 
III. The erection and commissioning of the plant requires greater technical know-how. 
IV. The fission by-products are generally radioactive and may cause a dangerous amount of 
radioactive pollution. 
V. Maintenance charges are high due to lack of standardization. Moreover, high salaries of specially 
trained personnel employed to handle the plant further raise the cost. 
VI. Nuclear power plants are not well suited for varying loads as the reactor does not respond to the 
load fluctuations efficiently. 
VII. The disposal of the by-products, which are radioactive, is a big problem. They have either to be 
disposed off in a deep trench or in a sea away from sea-shore. 
 
Schematic Arrangement of Nuclear Power Station: 
  
The schematic arrangement of a nuclear power station is shown in Fig; the whole arrangement can be 
divided into the following main stages: 
(i) Nuclear reactor 
(ii) Heat exchanger 
(iii) Steam turbine 
(iv) Alternator. 
 
 
 
 
(i) Nuclear reactor. It is an apparatus in which nuclear fuel (U ) is subjected to nuclear     fission. It controls 
the chain reaction* that starts once the fission is done. If the chain     reaction is not controlled, the result 
will be an explosion due to the fast increase in the     energy released.     A nuclear reactor is a cylindrical 
stout pressure vessel and houses fuel rods of Uranium,     moderator and control rods (See Fig.) The fuel 
rods constitute the fission material and     release huge amount of energy when bombarded with slow 
moving neutrons. The moderator consists of graphite rods which enclose the fuel rods. The moderator 
slows down the neutrons before they bombard the fuel rods. The control rods are of cadmium and are 
inserted into the reactor. Cadmium is strong neutron absorber and thus regulates the supply of neutrons 
for fission. When the control rods are pushed in deep enough, they absorb most of fission neutrons and 
hence few are available for chain reaction which, therefore, stops.  However, as they are being 
withdrawn, more and more of these fission neutrons cause fission and hence the intensity of chain 
reaction (or heat produced) is increased. Therefore, by pulling out the control rods, power of the nuclear 
reactor is increased, whereas by pushing them in, it is reduced. In actual practice, the lowering or raising 
of control rods is accomplished automatically according to the requirement of load. The heat produced in 
the reactor is removed by the coolant, generally a sodium metal. The coolant carries the heat to the   heat 
exchanger. 
 
 
 
 
(ii) Heat exchanger: The coolant gives up heat to the heat exchanger which is utilized in raising the steam. 
After giving up heat, the coolant is again fed to the reactor. 
(iii) Steam turbine: The steam produced in the heat exchanger is led to the steam turbine through a valve. 
After doing a useful work in the turbine, the steam is exhausted to condenser. The condenser condenses 
the steam which is fed to the heat exchanger through feed water pump. 
(iv) Alternator: The steam turbine drives the alternator which converts mechanical energy into electrical 
energy. The output from the alternator is delivered to the bus-bars through transformer, circuit breakers 
and isolators. 
 
Selection of Site for Nuclear Power Station: 
 
The following points should be kept in view while selecting the site for a nuclear power station: 
       (i) Availability of water. As sufficient water is required for cooling purposes, therefore, the 
           plant site should be located where ample quantity of water is available, e.g., across a river or  by 
sea-side. 
      (ii) Disposal of waste. The waste produced by fission in a nuclear power station is generally radioactive 
which must be disposed off openly to avoid health hazards. The waste should either be buried in a deep 
trench or disposed off in sea quite away from the sea shore. Therefore, the site selected for such a plant 
should have adequate arrangement for the disposal of radioactive waste. 
    (iii) Distance from populated areas. The site selected for a nuclear power station should be quite away 
from the populated areas as there is a danger of presence of radioactivity in the atmosphere near the 
plant. However, as a precautionary measure, a dome is used in the plant which does not allow the 
radioactivity to spread by wind or underground waterways. 
     (iv) Transportation facilities: The site selected for a nuclear power station should have adequate 
facilities in order to transport the heavy equipment during erection and to facilitate the move ment of the 
workers employed in the plant. From the above mentioned factors it becomes apparent that ideal choice 
for a nuclear power station would be near sea or river and away from thickly populated areas.