Nuclear power plants have several advantages including needing less space, being well-suited to meet large power demands, having reliable operation, and not being affected by adverse conditions. They also have disadvantages such as high capital costs, risks of radioactivity, inability to operate at variable loads, and high maintenance costs. The essential components of a nuclear reactor are the reactor core, reflector, control mechanism, moderator, coolant, and shielding. The document then provides details on various types of nuclear reactors including pressurized water reactors, boiling water reactors, CANDU reactors, fast breeders, and gas cooled reactors.

1. Nuclear Power Plant
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2. Advantages of Nuclear Power Plants
1. It needs less space as compared to conventional power stations
2. They are well suited to meet large power demands
3. They gives better performance
4. Fuel consumption is very small. So saving of cost of fuel transportation
5. They also produce valuable fissile material which is produced when fuel is
renewed
6. The operational of nuclear power plant is more reliable
7. Nuclear power plant are not affected by adverse conditions
8. Bigger capacity of power plants is an additional advantages
9. The expenditure on metal structure , piping, storage mechanism is much
lower
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4. Disadvantages of Nuclear Power Plants
1. Capital cost is high
2. Danger of radioactivity
3. These plants can not be operated at variable loads
4. The maintenance cost is very high
5. The disposal of the fission products is a big problem
6. Working condition in the nuclear power plant is detrimental to health
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5. ESSENTIAL COMPONENTS OF NUCLEAR REACTOR
1. Reactor Core 2. Reflector
3. Control Mechanism 4. Moderator
5 Coolant 6. Measuring
Instruments
7. Shielding
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6. 1. Reactor Core:
# It is the part where fission reaction takes place
# It consist fuel elements, Control Rods , Coolant and moderator
# Core is a circular cylinder with dia. 0.5 to 15 m
# The fuel elements are made of plates or rods
# These rods are packed in stainless steel or zirconium uranium metal
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7. 2. Reflector:
# A reflector is placed round the core
# It reflect the neutron which leaks out from the surface of the core.
# It is generally made up of same material as that of moderator.
3. Control Mechanism :
# It is the essential part of the reactor
# It is used for starting, normal operation and to shut down the reactor.
# It also maintain the chain reaction.
4. Moderator :
# Moderator is used to slow down the neutron fro high velocity
# It do not absorb the neutron
# Water heavy water, helium, graphite Beryllium are used as moderator
# Moderator must have high slowing Power, low parasite capture, non
corrosive, high melting point
# Moderator have high thermal conductivity, abundance in pure form
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8. 5. Coolant:
# The function of the coolant is to remove the intense heat produced in the
reactor and to bring out for being utilized.
# Coolant should have parasite capture, low melting point, high boiling
point, low viscosity
# It should have non corrosive property, non toxicity,
# Minimum induced activity ( Short half life , low energy emission)
# High density and high specific heat
6. Measuring Instruments:
# The purpose of the measuring instrument is to measure the thermal
neutron flux
# Neutron thermal flux determine the power developed by the reactor.
7. Shielding:
# It protect the reactor walls from the radiation damage
# It also protect personnel from the exposure to the radiations
# First is known as thermal shield made up of steel.
# Other or external shield is made up of concrete surrounding the reactor26 November 2020 DINESH PANCHAL 8

9. Power of the Nuclear Reactor :
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11. Pressurized Water Reactor(PWR)
It is a light water cooled and moderated thermal reactor having an unusual
design, using both natural and highly enriched fuel. The main parts of the
reactor are:
1. Pressure Vessel 2. Reactor thermal Shield 3.
Fuel Elements
4. Control Rods 5. Reactor Containment 6. Reactor
Pressurizere
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# Fig. Shows the PWR Reactor there are two circuits of water,
# one primary circuit of water which passes through the fuel core and the
radioactive.
# This circuit then produce steam in the secondary circuit which consist of heat
exchanger.
# Steam in the turbine is not radioactive and need to be shielded
# The pressure in the primary circuit is high so that boiling of water take place
at very high temp
# pressure is in the primary circuit is about 100 Kgf
# Water in the reactor act as coolant and as a moderator
# This reactor provide only the saturated steam. By providing the separate
furnace saturated steam can be made superheated

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Advantages of PWR :
1. Water used in the reactor is cheap and easily available
2. Reactor is compact and power density is high
3. Fission products remain contained in the reactor and are not
circulated
4. Small no. of rods are required
5. There is a complete freedom to inspect and maintain the
turbine.
6. This reactor reduce the fuel cost extracting more energy per unit
weight of the fuel.
Disadvantages of PWR :
1. Capital cost is high as the primary circuit require strong pressure
vessel
2. In the secondary circuit the thermodynamic efficiency of the of the
plant is low
3. Severe corrosion problem
4. It is imperative to shut down the reactor for the fuel charging which
require a couple of months

14. Boiling Water Reactor(BWR)
# In BWR enriched fuel is used.
# As compared to PWR the arrangement of the BWR is simple
# The plant can be safely operated using natural convection with in the core or
forced circulation
# For safe operation of the reactor pressure in the forced circulation must be
maintained irrespective of the load
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Advantages of PWR :
1. Heat exchanger is eliminated so there is gain in the thermal
efficiency
2. there is a use of lower pressure vessel so cost is reduced
3. The metal temp. remain low for given output conditions
4. The cycle of the BWR is more efficient than PWR for given pressure
and temperature.
5. The pressure inside the pressure vessel is not high so a
thicker vessel is not required
Disadvantages of PWR :
1. Possibility of the radioactive contamination in the turbine mechanism.
2. More safety and precaution is required
3. So Wastage of steam resulting in the lower thermal efficiency on part
of load operation
4. Boiling limits power density; only 3 to 5% by mass can be converted
to the steam per pass through the boiler.
5. The possibility of burn out of the fuel is more in this reactor
than PWR asd boiling of water on the surface of the fuel is allowed.

16. Canadian – Deuterium- Uranium Reactor( CANDU Reactor)
# In this reactor Heavy water Deuterium oxide is used as a moderator and
coolent
# This reactor was developed in Canada
# In this reactor natural uranium is used as a fuel
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17. This reactor has the following components:
1. Reactor Vessel and Core 2. Fuel 3. Control and protection system
4. Steam System1.
1. Reactor Vessel and Core:
# Vessel is a steel cylinder with horizontal axis having length 6m and
dia. 8 m
# This cylinder has pressure tubes which can withstand high pressure.
# The channel contain the fuel elements and pressurized coolant flow
along the channels and around the fuel elements
# Heat generated by the fission reaction is carried away by the coolant
# Coolant flow in the opposite direction in the adjacent channel
# Pressure is about 10 MPa and temp. is 370 degree
2. Fuel:
# Its fuel is normal i.e. uranium oxide
# The pellets are packed in corrosion resistance zirconium alloy tube
nearly 0.5 m long and 1.3 cm. in dia.
# Shorts rods are combined in a bundle rod 37 rods and12 bundles are
placed in each pressure tube.
# Total mass of the fuel in the core is about 97000 Kg.26 November
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18. 3. Control and protection system
# No. of rods of cadmium are used to control the speed of the
neutrons these rods are used to start and stop the reactor
# In addition to above, less strongly absorbing rods are used to control
power variations during reactor operation
# In emergency situation, the should down rods would immediately
drop-in to the core.
4. Fuel:
# The respective ends of the tube are all connected in to the inlet and
outlet headers
# The high temp. coolant leaving the reactor passes out the outlet
header to a steam generator.
# Steam is generated at a temp. of 265 degree
The reactor vessel and the steam generator are enclosed by a concrete
containment structure
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Advantages of CANDU:
1. Low fuel consumption
2. Enriched fuel is not required
3. Cost of the vessel is less as it has not to withstand high pressure.
4. Less time is needed to construct the reactor as comparison to PWR
and BWR
5. The moderator can be kept at low temp. which increases its
effectiveness in slowing down the neutrons
Disadvantages of CANDU :
1. It require a very high standard of design, manufacturing and
maintenance.,
2. The cost of heavy water is very high
3. There are leakage problems.
4. The size of the reactor is extremely large as compared to the PWR
and BWR

20. Sodium Graphite Reactor (Liquid Metal Cooled Reactor)
# I t is the typical Liquid metal reactor
# In this reactor Sodium works as a coolant and graphite as a moderator
# Sodium boils at 880 degree under atm. Pressure and freezes at 95 degree.
# Sodium is first melted melted by electric heating and pressurized to 7 bar then
circulated by pump
# This reactor has two coolant circuit loops
# The primary circuit has liquid sodium which circulate in the vessel core and
get heated by means of fission reaction.
# This liquid sodium get cooled in the intermediate reactor and goes back to
the reactor
#The second circuit has an alloy of sodium and potassium in liquid form This
coolant takes heats from the intermediate heat exchanger and gets heat
from the liquid sodium and gives its heat to the water in the secondary
circuit and cools down and then back to the primary circuit.
# Water gains the heat in the secondary circuit and converted in to the stem
and then this sream is passed to the turbine. After passing through the
turbine this steam get converted in to the water then this water is again sent
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21. Fig. of Sodium Graphite Reactor
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Advantages of SGR:
1. The sodium as a coolant need not to be pressurized
2. High thermal efficiency at low cost
3. Low cost of the Graphite moderator can be used
4. Graphite moderator has high mechanical strength even at high
temp.
5. Excellent heat removal
6. High Convection Ratio
7. Superheating of the steam is possible
8. Size of the reactor is small
Disadvantages of SGR :
1. Sodium react violently with water and air
2. Thermal stresses are the problems
3. Intermediate system is necessary to separate active sodium from
water
4. Heat exchanger must be leak proof
5. The leakage of sodium is very dangerous.
6. It is necessary to shield the primary and secondary cooling system

23. Fast Breeder Reactor
# It has a small vessel in which necessary amount of enriched Plutonium is
kept without using moderator
# A fissile material, which absorb neutron, surrounds the vessel.
# The reactor core is cooled with the liquid metal
# Necessary neutron is shielded is provided by the use of light water, oil or
graphite
# Additional shielding is provided for gamma rays
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Advantages of Breeder Rector:
1. The moderator is not required
2. High breeding is possible
3. Small core is sufficient
4. High burn up of fuel is achievable
5. Abortion of neutron is low
6. The parasite absorption of fuel is achievable
Disadvantages of Breeder Reactor :
1. Require highly enriched fuel is required
2. It is necessary to provide safety against melt down
3. Neutron flux is high at the center of the core
4. Specific power of the reactor is low
5. There is major problem of handling of sodium as it become hot and
radioactive

25. Gas Cooled Reactor (GCR)
# In reactor coolant can be used air, hydrogen, helium or carbon dioxide
# Generally inert gases are used such as helium and carbon dioxide
# Graphite is used as a moderator.
# The problem of the corrosion is reduced
# This reactor is more safe in case of accident and failure of circulating pump
# In GCR the shield is much reduced
# There are two type of Gas cooled reactor (i) Gas cooled , Graphite
moderator Reactor (ii) High temp. gas cooled reactor
The coolant pressure GMGM are about 7 bar and 336 degree and in HTGC
pressure is 15 to 30 bar and temp. is about 700 degree to 800 degree
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Advantages of GCR:
1. The processing of the fuel is simpler
2. No corrosion problem
3. As a result of low parasite absorption it gives better neutron economy
4. Graphite remain stable under irradiation at high temp.
5. The use of carbon dioxide as a coolant completely
eliminates the possibility of explosion
6. The T uranium carbide and graphite are able to resist high temp.,
and therefore, the problem of limiting the fuel element temp, is not
as serious as in other reactor
Disadvantages of GCR:
1. The fuel loading is more elaborate and costly
2. It The power density is very low
3. Since critical mass is high therefore large amount of fuel loading is
initially required
4. If helium is used instead of carbon oxide , the leakage is the main
problem
5. The control is more complicated.

28. Nuclear Power Station
1. Tarapur Power Plant:
# Situated in Maharastra . 65 miles North Mumbai
# Capacity 380 MW
# Steam Pressure and temp. is 35 bar and 240 degree
2.Rana Partap Sagar Power Plant:
# Situated near Kota in Rajastan
# Capacity 4oo MW (2x200MW)
# Steam Pressure and temp. is 40bar and 250 degree
3. Kalpakkam Power Plant:
# Situated near Chennai in Tamil Nadu
# Capacity 47o MW (2x235MW)
# Steam Pressure and temp. is 40bar and 250 degree
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29. 4. Narora Power Plant:
# Situated in U.P.
# Capacity 47o MW (2x235MW)
# Steam Pressure and temp. is 40bar and 250 degree
5. Kakarpar Power Plant:
# Situated Surat in Gujrat
# Capacity 4oo MW (2x200MW)
# Proposed
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30. Nuclear Waste
• It looks exactly like the fuel that was loaded into the reactor
• . But since nuclear reactions have occurred, the contents aren’t quite
the same.
• Before producing power, the fuel was mostly Uranium (or Thorium),
oxygen, and steel. Afterwards, many Uranium atoms have split into
various isotopes of almost all of the transition metals on your periodic
table of the elements.
• The waste, sometimes called spent fuel, is dangerously radioactive,
and remains so for thousands of years.
• When it first comes out of the reactor, it is so toxic that if you stood
within a few meters of it while it was unshielded, you would receive a
lethal radioactive dose within a few seconds and would die of acute
radiation sickness within a few days.
• Hence all the worry about it.
• In practice, the spent fuel is never unshielded. It is kept underwater
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