description on nuclear power-plant........

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CHAPTER-1
INTRODUCTION
A nuclear power plant or nuclear power station is a thermal power station in which the
heat source is a nuclear reactor. As is typical in all conventional thermal power stations
the heat is used to generate steam which drives a steam turbine connected to an
electric generator which produces electricity. As of 23 April 2014, the IAEA report there
are 435 nuclear power reactors in operation operating in 31 countries. Nuclear power
stations are usually considered to be base load stations, since fuel is a small part of the
cost of production. Their operations and maintenance (O&M) and fuel costs are, along
with hydropower stations, at the low end of the spectrum and make them suitable as
base-load power suppliers. The cost of spent fuel management, however, is somewhat
uncertain.

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CHAPTER-2
HISTORY
The neutron was discovered in 1932. The concept of a nuclear chain reaction brought
about by nuclear reactions mediated by neutrons was first realised shortly thereafter,
by Hungarian scientist “Leo Szilard”, in 1933. Inspiration for a new type of reactor using
uranium came from the discovery by “Lise Meitner”,” Fritz Stresemann” and “Otto
Hahn” in 1938 that bombardment of uranium with neutrons produced a barium residue,
which they reasoned was created by the fissioning of the uranium nuclei On june-27-
1954 the USSR Obninsk Nuclear Power Plant became the world’s first nuclear power
plant to generate electricity for a power grid, and produced around 5 megawatts of
electric power. The first commercial nuclear power station, calder Hall in Sell afield,
England was opened in 1956 with an initial capacity of 50MW (Later 200MW).
Tarapur Atomic Power Station (T.A.P.S.) was the first nuclear power plant in India. The
construction of the plant was started in 1962 and the plant went operational in 1969.
The 320 MW Tarapur nuclear power station housed two 160 MW boiling water reactors
(BWRs), the first in Asia. The Tarapur Plant was originally constructed by the American
companies Bechtel and GE, under a 1963 123 Agreement between India, the United
States, and the IAEA. The Tarapur Atomic Power Station is under the control of Nuclear
Power Corporation of India Limited.
Fig.1 TARAPUR NUCLEAR POWER STATION

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CHAPTER-3
NUCLEAR REACTION
In nuclear physics and nuclear chemistry, a nuclear reaction is semantically considered
to be the process in which two nuclei, or else a nucleus of an atom and a subatomic
particle such as a proton, neutron, or high energy electron8 from outside the atom,
collide to produce one or more nuclides that are different from the nuclide7s8 that
began the process. Thus, a nuclear reaction must cause a transformation of at least one
nuclide to another. If a nucleus interacts with another nucleus or particle and they then
separate without changing the nature of any nuclide, the process is simply referred to as
a type of nuclear scattering, rather than a nuclear reaction. There are two types of
nuclear reactions.
 Nuclear Fission
 Nuclear fusion
Nuclear Fusion
In nuclear physics, nuclear fusion is a nuclear reaction in which two or more atomic
nuclei collide at a very high speed and Join to form a new type of atomic nucleus. During
this process, matter is not conserved because some of the matter of the fusing nuclei is
converted to photons (energy). Fusion power is the energy generated by nuclear fusion
processes. The origin of the energy released in fusion of light elements is due to
interplay of two opposing forces, the nuclear force which combines together protons
and neutrons, and the Coulomb force which causes protons to repel each other. The
protons are positively charged and repel each other but they nonetheless stick together,
demonstrating the existence of another force referred to as nuclear attraction. This
force, called the nuclear force, overcomes electric repulsion in a very close range. Most
nuclear fusion reactions involve the fusion of two hydrogen isotopes (Deuterium and
Tritium) to form a helium atom releasing huge amounts of energy and a neutron.

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Fig-2 A schematic representation on nuclear Fusion
Nuclear fusion is currently in its experimental phases and is not being utili9ed for
commercial purposes due to its requirements of high initial energy and pressure so as to
overcome the columbic forces and bring the nuclei in close proximity.
Nuclear Fission
In nuclear physics and nuclear chemistry, nuclear fission is either a nuclear reaction or
radioactive decay process in which the nucleus of an atom splits into smaller
parts7lighter nuclei8. The fission process often produces free neutrons and photons (in
the form of gamma rays), and releases a very large amount of energy even by the
energetic standards of radioactive decay.
Fig.3 A schematic representation on nuclear fission.

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Fission as encountered in the modern world is usually a deliberately produced man
made nuclear reaction induced by a neutron. In an induced fission reaction, a neutron is
absorbed by uranium-235 nucleus turning it briefly into an excited uranium-236 nucleus,
with the excitation energy provided by the kinetic energy of the neutron plus the forces
that bind the neutron. The uranium-236 in turn splits into fast moving lighter elements
(fission products) and releases three free neutrons at the same time, one or more
“prompt gamma rays” are produced as well.
COMPARISION BETWEEN NUCLEAR FUSION AND NUCLEAR FISSION
Nuclear Fission Nuclear Fusion
Definition Fission is the splitting of a large
atom into two or more smaller
ones
nuclear fusion is a reaction in
which two or more atomic nuclei
come close enough to form one
or more different atomic nuclei
and subatomic particles
Natural
occurrence of
the process
Fission reaction does not
normally occur in nature
Fusion occurs in stars, like Sun
By products of
the reaction
Fission produces many highly
radioactive particles
Few radioactive particles are
produced by fusion reaction
Conditions Critical mass of the substance and
high speed neutrons are required
High density, high temperature
environment is required.
Nuclear
Weapon
One class of nuclear weapons is
a fission bomb, also known as
atomic bomb
One class of nuclear weapons is
a hydrogen bomb
Fuel Uranium is a primary fuel used in
nuclear fission
Hydrogen isotopes are the
primary fuel used in nuclear
fusion
[Table.1 comparison between nuclear fission and fusion]

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CHAPTER 4
COMPONENTS OF A NUCLEAR POWER-PLANT
The VariousComponentsof a Nuclear Power Plantare ;-
 Nuclear reactor: A nuclear reactor is a device to initiate and control a
sustained nuclear chain reaction. In its central part, the reactor core’s heat
is generated by controlled nuclear fission. With this heat, a coolant is
heated as it is pumped through the reactor and thereby removes the
energy from the reactor. Heat from nuclear fission is used to raise steam,
which runs through turbines, which in turn powers either ship’s propellers
or electrical generators.
 Cooling System: A cooling system removes heat from the reactor core and
transports it to another area of the plant, where the thermal energy can be
harnessed to produce electricity or to do other useful work. Typically the
hot coolant is used as a heat source for a boiler, and the pressurised steam
from that one or more steam turbine driven electrical generators. Almost
all currently operating nuclear power plants are light water reactors using
Fig.4 A schematic diagram of nuclear power-plant

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ordinary water under high pressure as coolant and neutron moderator. A
neutron moderator slows down the speed of the neutron as a medium,
thereby turning them into thermal neutrons capable of sustaining a nuclear
chain reaction involving uranium-235.
 Steam Generator/Boiler: The heat from the reactor is used to convert
water to steam. this steam is used to run a turbine to produce electricity.
The position of the boiler depends on the type of reactor. The two most
widely used reactorsare:--
 Pressurised Water Reactor (PWR)
 Boiling Water Reactor (BWR)
 Pressurised Water Reactor(PWR):- These constitute the majority of the
reactors, the above diagram shows a PE2. The primary characteristic of PE2
is a pressurize, that is a speciali9ed pressure vessel that stores the coolant
in it and is sent into the reactor as per the requirement. In a PE2 the boiler
is situated in a different assembly, away from the reactor. Two fluid
systems are used in a PE2, one coolant cycle circulated in the reactor and
pumped into the steam generator. This hot fluid from the reactor is used to
heat the water to generate steam to be sent to the steam turbine. The
water used in the turbine is not radioactive.
 Boiling Water Reactor (BWR):- BWR are characteri9ed by boiling water
around the fuel rods in the lower portion of a primary reactor pressure
vessel. A boiling water reactor uses – U235, enriched as uranium dioxide,
as its fuel. The fuel is assembled into rods housed in a steel vessel that is
submerged in water. The nuclear fission causes the water to boil,
generating steam. This steam flows through pipes into turbines. The
turbines are driven by the steam, and this process generates electricity. The
main characteristic is that the boiler here is the reactor itself and the main

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characteristic is that the boiler here is the reactor itself and the coolant
itself is used to drive the turbines. The fluid used in the turbine is
radioactive coolant itself is used to drive the turbines. The fluid used in the
turbine is radioactive.
 Feed water pump:- The water level in the steam generator and nuclear
reactor is controlled using the feed water system. The feed water pump has
the task of taking the water from the condensate system, increasing the
pressure and forcing it into either the steam generators (in the case of a
pressurised water reactor) or directly into the reactor (for boiling water
reactors).
 Steam Turbine:- The steam generated from the boiler is used to drive the
turbine. This turbine is connected to an electric generator so as to generate
electricity. Care is taken in maintaining the condition of the turbine as it
handles steam of very high heat capacity. The turbines used in BWR have to
be radioactively sealed so as to avoid leakage of the radioactive water.
 Electric Generator:- he generator converts kinetic energy supplied by the
turbine into electrical energy. Low pole AC synchronous generators of high
rated power are used.
 Cooling Towers:- A cooling tower is a heat rejection device which extracts
Waste heat to the Atmosphere through the cooling of a water stream to a
lower temperature. cooling towers may either use the Evaporation of water
to remove process heat and cool the working fluid to near the Wet bulb air
temperature or, in the case of Closed circuit dry cooling towers, rely solely
on air to cool the working fluid to near the Dry bulb air temperature.

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CHAPTER 5
Parts of Nuclear Reactor:-
1. Nuclear fuel:- Fuel of a reactor should be fissionable material which
can be defined as a fissionable material which can be defined as an
element or isotope whose nuclei can be caused to undergo nuclear
fission nuclear bombardment and to produce a fission chain
reaction. The fuels used are U238, U235, U234 Fertile materials,
those which can be transformed into fissile materials, cannot sustain
chain reactions. Ehen a fertile material is hit by neutrons and absorbs
some of them, it is converted to fissile material.
2. Reactor core:- This contains a number of fuel rods made of fissile
material.
3. Control rods :- The energy inside the reactor is controlled by the
control rod. These are in cylindrical or sheet form made of boron or
cadmium. These rods can be moved in and out of the holes in the
reactor core assembly.

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4. Reactor vessel :- It is a strong walled container housing the core of
the power reactor. It contains moderate, reflector, thermal shielding
and controlrods.
5. Coolant:- This removes heat from the core produced by
nuclear reaction. The types of coolants used are carbon
dioxide, air, hydrogen, helium, sodium or sodium
potassium.

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CHAPTER 6
Nuclear Power in India:-
Nuclear power is the fourth largest source of electricity in India after thermal,
hydroelectric and renewable sources of electricity. As of 2017, India has 21
nuclear reactors in operation in 7 nuclear power plants, having an installed
capacity of 6780 MW and producing a total of 30,292.91 GWh of electricity while
6 more reactors are under construction and are expected to generate an
additional 4,300 MW.
NUCLEAR POWER-PLANT IN INDIA

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Advantages of Nuclear Power Plant:-
 Space requirement of a nuclear power plant is less as compared to other
conventional power plants of equal size.
 A nuclear power plant consumes very small Quantity of fuel. Thus fuel
transportation costis less and large fuel storagefacility is not needed.
 There is increased reliability of operation.
 Nuclear power plants are not affected by adverseweather conditions.
 Nuclear power plants are well suited to meet large power demands. They
give better performanceat higher load factors (80-90%).
 Itdoes not require large quantity of water.
 Currently, fossil fuels are consumed faster than they are produced, so in the
next future these resources may be reduced or the price may increase
becoming inaccessible for mostof the population.
Disadvantages of Nuclear Power Plant:-
 Initial cost of nuclear power plant is higher as compared to hydro or steam
power plant.
 Nuclear power plants are not well suited for varying load conditions.
 Maintenance costof the plant is high.
 Itrequires highly trained personnelto handle nuclear power plants.
 Nuclear power plants are objectives of terroristorganizations.
 Decommissioning of nuclear power stations is expensive and takes a long
time.

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CHAPTER 7
Conclusion
Widely used nuclear energy can be of great benefit for mankind. It can bridge the gap
caused by inadequate coal and oil supply. It should be used to as much e>tent as
possible to solve power problem. With further developments, it is likely that the cost of
nuclear power stations will be lowered and that they will soon be competitive. nuclear
power stations are taking an important place in the development of the power
potentials of the nations of the world today in the context of “The changing pattern of
Power”

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CHAPTER 8
Reference:-
 An Introduction to Nuclear Power generation by P.K NAG,
 Nuclear power-plant by R.K Rajput,
 http://en.wikipedia.org/wiki/Nuclear_reaction
 http://en.wikipedia.org/wiki/Nuclear_fission