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Nuclear Power Plant
Abstract A nuclear power plant 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 a electric generator which produces electricity. Nuclear power plants are usually considered to be base load stations, since fuel is a small part of the cost of production. Nuclear power plants are not located according to specific attributes of geography, and are therefore found all over the world. Although as a coin has two sides, nuclear power plants also have many merits and demerits. The present status of nuclear energy and future is also discussed further.
Dept of Mechanical Engineering, JCE, Belgaum
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Nuclear Power Plant
Acknowledgement I would like to acknowledge the contribution of all the people who have helped in reviewing this report. I would like to sincerely thank our principal Dr. K. G. Vishwanath, Head of Department Prof. D. B. Patil, staff coordinator Dr. B. Y. Patil and seminar guide Prof. S.M. Kerur for his guidance and throughout the seminar work. I thank my faculty for giving me an opportunity to learn and present the seminar. If not for the above mentioned people my seminar would never have been completed successfully. I would also like to thank our families and friends who ed us in the course of writing this report.
Dept of Mechanical Engineering, JCE, Belgaum
Page 2
Nuclear Power Plant
Table Of Contents
1. 2. 3. 4. 5. 6. 7. 8. 9. 10.
Introduction……………………………………………………4 Literature Survey………………………………………………5 History ………………………………………………………...6 Nuclear Reactions……………………………………………...8 Components…………………………………………………....11 Parts of Nuclear Reactor……………………………………….14 Nuclear Power In India………………………………………...16 Advantages and Disadvantages………………………………...17 Conclusion……………………………………………………...19 References……………………………………………………...20
Dept of Mechanical Engineering, JCE, Belgaum
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Chapter 1 Introduction Conventional thermal power stations use oil or coal as the source as the source of energy. The reserves of these fuels are becoming depleted in many countries and thus there is a tendency to seek alternative sources of energy. In a nuclear power station instead of a furnace there is a nuclear reactor, in which heat is generated by splitting atoms of radioactive material under suitable conditions. The conversion to electrical energy takes place indirectly, as in conventional thermal power plants. The heat is produced by fission in a nuclear reactor. Directly or indirectly, water vapor (steam) is produced. The pressurized steam is then usually fed to a multi-stage steam turbine. For economical use in a power system a nuclear power station generally has to be large and where large units are justifiable.
Fig 1. An image of the Kudankulam nuclear power plant at Tirunelveli, Tamil Nadu. As of 23 April 2014, the International Atomic Energy Agency reports that there are 435 nuclear power reactors in operation operating in 31 countries.
Dept of Mechanical Engineering, JCE, Belgaum
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Chapter 2 Literature Survey 1. An Introduction to Nuclear Power Generation by Christopher E. Bremen, California institute of technology Pasadena, California. The book is an introduction to a graduate level (or advanced undergraduate level) course in nuclear power generation. It assumes a basic knowledge of physics, fluid mechanics and heat transfer. Of course, the design of a nuclear power plant involves a broad range of engineering expertise. This monograph focuses on the thermo hydraulics and neutronics of nuclear power generation and, in particular, on the interplay between these that determines the design of the reactor core. The book also has some brief description of other critical issues such as nuclear reactor safety. This necessarily includes brief descriptions of the three major accidents (Three Mile Island, Chernobyl and Fukushima) that have influenced the development of nuclear power.
Chapter 3 Dept of Mechanical Engineering, JCE, Belgaum
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History of Nuclear Energy and Power Generation The neutron was discovered in 1932. The concept of a nuclear chain reaction brought about by nuclear reactions mediated by neutrons was first realized shortly thereafter, by Hungarian scientist Leó Szilárd, in 1933. Inspiration for a new type of reactor using uranium came from the discovery by Lise Meitner, Fritz Strassmann and Otto Hahn in 1938 that bombardment of uranium with neutrons (provided by an alpha-on-beryllium fusion reaction, a "neutron howitzer") produced a barium residue, which they reasoned was created by the fissioning of the uranium nuclei. On June 27, 1954, the USSR's 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 Sellafield, England was opened in 1956 with an initial capacity of 50 MW (later 200 MW). India's first research nuclear reactor and its first nuclear power plant were built with assistance from Canada. The 40 MW research reactor agreement was signed in 1956, and CIRUS achieved first criticality in 1960. This reactor was supplied to India on the assurance that it would not be used for military purposes, but without effective safeguards against such use. The technical and design information were given free of charge by Atomic Energy of Canada Limited to India. The United States and Canada terminated their assistance after the detonation of India's first nuclear explosion in 1974. Tarapur Atomic Power Station located in Tarapur, Maharashtra is the first nuclear power reactor of India. It was estabilished in October 28, 1969. It has a total capacity of 1,400MW. Fig 2. The image is a view of the Tarapur Nuclear power plant.
Chapter 4 Nuclear Reactions In nuclear physics and nuclear chemistry,
a nuclear
reaction is semantically considered to be the process in which two nuclei, or else a Dept of Mechanical Engineering, JCE, Belgaum
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Nuclear Power Plant
nucleus
of
an
particle (such
as
atom a
and
a subatomic
proton, neutron,
or
high energy electron) from outside the atom, collide to produce one or more nuclides that are different from the nuclide(s) 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 Fusion Nuclear Fission
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 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 is the process that powers active or "main sequence" stars. 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. Fig 3. A schematic representation of the equation of a nuclear fusion reaction.
Dept of Mechanical Engineering, JCE, Belgaum
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Nuclear fusion is currently in its experimental phases and is not being utilized for commercial purposes due to its requirements of high initial energy and pressure so as to overcome the coulombic 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 parts (lighter nuclei). 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 4. A schematic representation of the equation of a nuclear fission reaction. Fission as encountered in the modern world is usually a deliberately produced manmade 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
Comparison between Nuclear Fusion and Nuclear Fission Nuclear Fission
Definition
Fission is the splitting of a large atom into two or more smaller ones.
Nuclear Fusion Fusion is the fusing of two or more lighter atoms into a larger one.
Natural Fission reaction does not normally occurrence of occur in nature. the process
Fusion occurs in stars, such as the sun.
Byproducts of Fission produces many highly the reaction radioactive particles.
Few radioactive particles are produced by fusion reaction
Conditions
Critical mass of the substance and high-speed neutrons are required.
Dept of Mechanical Engineering, JCE, Belgaum
High density, high temperature environment is required. Page 8
Nuclear Power Plant
Nuclear Fission Takes little energy to split two atoms Energy in a fission reaction. Requirement
Nuclear Fusion Extremely high energy is required to bring two or more protons close enough that nuclear forces overcome their electrostatic repulsion.
The energy released by fission is a million times greater than that Energy Released released in chemical reactions, but lower than the energy released by nuclear fusion.
The energy released by fusion is three to four times greater than the energy released by fission.
One class of nuclear weapon is a Nuclear weapon fission bomb, also known as an atomic bomb or atom bomb.
One class of nuclear weapon is the hydrogen bomb, which uses a fission reaction to "trigger" a fusion reaction.
Energy Fission is used in nuclear power production plants.
Fusion is an experimental technology for producing power.
Uranium is the primary fuel used in Fuel power plants.
Hydrogen isotopes (Deuterium and Tritium) are the primary fuel used in experimental fusion power plants.
Chapter 5 Components of a Nuclear Power Plant
Dept of Mechanical Engineering, JCE, Belgaum
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Fig 5. The above figure shows the various components and the schematic layout of a nuclear power plant.
The Various Components of a Nuclear Power Plant are:
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 pressurized steam from that one or more steam turbine driven electrical generators. Almost all currently operating nuclear power
Dept of Mechanical Engineering, JCE, Belgaum
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plants are light water reactors using ordinary water under high pressure as coolant and neutron . A neutron 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. Heavy water reactors use deuterium oxide which has similar properties to ordinary water but much lower neutron capture, allowing more thorough moderation.
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 reactors are
Pressurized Water Reactor (PWR): These constitute the majority of the reactors, the above diagram shows a PWR. The primary characteristic of PWR is a pressurizer, that is a specialized pressure vessel that stores the coolant in it and is sent into the reactor as per the requirement. In a PWR the boiler is situated in a different assembly, away from the reactor. Two fluid systems are used in a PWR, 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: BWRs are characterized by boiling water around the fuel rods in the lower portion of a primary reactor pressure vessel. A boiling water reactor uses 235U, 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 coolant itself is used to drive the turbines. The fluid used in the turbine is radioactive.
Safety Valves: In the event of an emergency, safety valves can be used to prevent pipes from bursting or the reactor from exploding. The valves are designed so that they can derive all of the supplied flow rates with little increase in pressure. In the case of the BWR, the steam is directed into the suppression chamber and condenses there. The chambers on a heat exchanger are connected to the intermediate cooling circuit.
Feedwater pump: The water level in the steam generator and nuclear reactor is controlled using the feedwater system. The feedwater pump has the task of taking the water from the condensate system, increasing the pressure and forcing it into
Dept of Mechanical Engineering, JCE, Belgaum
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either the steam generators (in the case of a pressurized 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 BWRs have to be radioactively sealed so as to avoid leakage of the radioactive water.
Electric Generator: The 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.
Emergency Power Supply: Most nuclear plants require two distinct sources of offsite power feeding station service transformers that are sufficiently separated in the plant's switchyard and can receive power from multiple transmission lines. Nuclear power plants are equipped with emergency power systems to maintain safety in the event of unit shutdown and loss of offsite power. Batteries provide uninterruptible power to instrumentation, control systems, and valves.. The emergency diesel generators do not power all plant systems, only those required to shut the reactor down safely, remove decay heat from the reactor, provide emergency core cooling, and, in some plants, spent fuel pool cooling.
Chapter 6 Parts of Nuclear Reactor
Dept of Mechanical Engineering, JCE, Belgaum
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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
caused
undergo
to
be
nuclear fission nuclear bombardment
and
to
produce a fission chain reaction. The fuels used are: U238, U235, U 234, UO2. Fertile materials, those which
can
be
transformed into fissile materials, cannot sustain chain reactions. When a fertile material is hit by neutrons
and
absorbs
some of them, it is converted
to
material.U238 232
are
fissile and
Th
examples
of
fertile materials used for reactor purposes.
Reactor core: This contains a number of fuel rods made of fissile material.
Dept of Mechanical Engineering, JCE, Belgaum
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: This material in the reactor core is used to moderate or to reduce the neutron speeds to a value that increases the probability of fission occurring.
Control rods: The energy inside the reactor is controlled by the control rod. These are in cylindrical or sheet form made of boron or cium. These rods can be moved in and out of the holes in the reactor core assembly.
Reflector: This completely surrounds the reactor core within the thermal shielding arrangement and helps to bounce escaping neutrons back into the core. This conserves the nuclear fuel.
Reactor vessel: It is a strong walled container housing the core of the power reactor. It contains moderate, reflector, thermal shielding and control rods.
Biological shielding: Shielding helps in giving protection from the deadly α- and βparticle radiations and γ-rays as well as neutrons given off by the process of fission within the reactor.
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.
Dept of Mechanical Engineering, JCE, Belgaum
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Chapter 7 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 2013, India has 21 nuclear reactors in operation in 7 nuclear power plants, having an installed capacity of 5780MW and producing a total of 30,292.91 GWh of electricity while seven other reactors are under construction and are expected to generate an additional 6,100 MW. Power
Total capacity
Operator
State
Type
Units
Kaiga
NPCIL
Karnataka
PHWR
220 x 4
880
Kakrapar
NPCIL
Gujarat
PHWR
220 x 2
440
Madras
NPCIL
Tamil Nadu
PHWR
220 x 2
440
Narora
NPCIL
Uttar Pradesh
PHWR
220 x 2
440
station
(MW)
100 x 1 Rajasthan
NPCIL
Kota Rajasthan
PHWR
200 x 1
1180
220 x 4
Tarapur
NPCIL
Maharashtra
Kudankulam
NPCIL
Tamil Nadu
BWR
160 x 2
PHWR
540 x 2
VVER-1000 1000 x 1
1440
1000
Chapter 8 Dept of Mechanical Engineering, JCE, Belgaum
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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 cost is less and large fuel storage facility is not needed.
There is increased reliability of operation.
Nuclear power plants are not affected by adverse weather conditions.
Nuclear power plants are well suited to meet large power demands. They give better performance at higher load factors (80-90%).
Materials expenditure on metal structures, piping, storage mechanisms are much lower for a nuclear power plant than a coal burning power plant.
It does not require large quantity of water.
The generation of electricity through nuclear energy reduces the amount of energy generated from fossil fuels (coal and oil). Less use of fossil fuels means lowering greenhouse gas emissions (CO2 and others).
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 most of the population.
The production of electric energy is continuous. A nuclear power plant is generating electricity for almost 90% of annual time. It reduces the price volatility of other fuels such as petrol.
Disadvantages of Nuclear Power Plant Initial cost of nuclear power plant is higher as compared to hydro or steam power plant.
Dept of Mechanical Engineering, JCE, Belgaum
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Nuclear power plants are not well suited for varying load conditions. Radioactive wastes if not disposed carefully may have bad effect on the health of workers and other population. Maintenance cost of the plant is high. It requires highly trained personnel to handle nuclear power plants. Nuclear power plants generate external dependence. Not many countries have uranium mines and not all the countries have nuclear technology, so they have to hire both things overseas. Nuclear power plants are objectives of terrorist organizations. Decommissioning of nuclear power stations is expensive and takes a long time. Nuclear accidents can spread 'radiation producing particles' over a wide area, This radiation harms the cells of the body which can make humans sick or even cause death. Illness can appear or strike people years after they were exposed to nuclear radiation and genetic problems can occur too. A possible type of reactor disaster is known as a meltdown. In a meltdown, the fission reaction of an atom goes out of control, which leads to a nuclear explosion releasing great amounts of radioactive particles into the environment. Chernobyl and Fukushima are the worst nuclear accidents to date causing many lives and leakage of radiation.
Chapter 9 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 extent 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. With the depletion of fuel reserves and the question of transporting fuel over long distances, nuclear power Dept of Mechanical Engineering, JCE, Belgaum
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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.
Chapter 10 References An Introduction to Nuclear Power Generation by Christopher E. Bremen, California institute of technology Pasadena, California. Safety of the Indian Pressurized Water Reactors, Department of Atomic Energy,
Government of India. http://nuclear-energy.net/advantages-and-disadvantages-of-nuclear-energy.html http://en.wikipedia.org/wiki/Nuclear_reaction http://en.wikipedia.org/wiki/Nuclear_fission http://en.wikipedia.org/wiki/Nuclear_power_in_India http://en.wikipedia.org/wiki/Nuclear_reactor
Dept of Mechanical Engineering, JCE, Belgaum
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http://en.wikipedia.org/wiki/Nuclear_fission http://en.wikipedia.org/wiki/Nuclear_power http://en.wikipedia.org/wiki/Nuclear_power_plant http://www.cyberphysics.co.uk/topics/nuclear/advantages_disadvantages_nuclear_ power.htm
Dept of Mechanical Engineering, JCE, Belgaum
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Abstract A nuclear power plant 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 a electric generator which produces electricity. Nuclear power plants are usually considered to be base load stations, since fuel is a small part of the cost of production. Nuclear power plants are not located according to specific attributes of geography, and are therefore found all over the world. Although as a coin has two sides, nuclear power plants also have many merits and demerits. The present status of nuclear energy and future is also discussed further.
Dept of Mechanical Engineering, JCE, Belgaum
Page 1
Nuclear Power Plant
Acknowledgement I would like to acknowledge the contribution of all the people who have helped in reviewing this report. I would like to sincerely thank our principal Dr. K. G. Vishwanath, Head of Department Prof. D. B. Patil, staff coordinator Dr. B. Y. Patil and seminar guide Prof. S.M. Kerur for his guidance and throughout the seminar work. I thank my faculty for giving me an opportunity to learn and present the seminar. If not for the above mentioned people my seminar would never have been completed successfully. I would also like to thank our families and friends who ed us in the course of writing this report.
Dept of Mechanical Engineering, JCE, Belgaum
Page 2
Nuclear Power Plant
Table Of Contents
1. 2. 3. 4. 5. 6. 7. 8. 9. 10.
Introduction……………………………………………………4 Literature Survey………………………………………………5 History ………………………………………………………...6 Nuclear Reactions……………………………………………...8 Components…………………………………………………....11 Parts of Nuclear Reactor……………………………………….14 Nuclear Power In India………………………………………...16 Advantages and Disadvantages………………………………...17 Conclusion……………………………………………………...19 References……………………………………………………...20
Dept of Mechanical Engineering, JCE, Belgaum
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Nuclear Power Plant
Chapter 1 Introduction Conventional thermal power stations use oil or coal as the source as the source of energy. The reserves of these fuels are becoming depleted in many countries and thus there is a tendency to seek alternative sources of energy. In a nuclear power station instead of a furnace there is a nuclear reactor, in which heat is generated by splitting atoms of radioactive material under suitable conditions. The conversion to electrical energy takes place indirectly, as in conventional thermal power plants. The heat is produced by fission in a nuclear reactor. Directly or indirectly, water vapor (steam) is produced. The pressurized steam is then usually fed to a multi-stage steam turbine. For economical use in a power system a nuclear power station generally has to be large and where large units are justifiable.
Fig 1. An image of the Kudankulam nuclear power plant at Tirunelveli, Tamil Nadu. As of 23 April 2014, the International Atomic Energy Agency reports that there are 435 nuclear power reactors in operation operating in 31 countries.
Dept of Mechanical Engineering, JCE, Belgaum
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Nuclear Power Plant
Chapter 2 Literature Survey 1. An Introduction to Nuclear Power Generation by Christopher E. Bremen, California institute of technology Pasadena, California. The book is an introduction to a graduate level (or advanced undergraduate level) course in nuclear power generation. It assumes a basic knowledge of physics, fluid mechanics and heat transfer. Of course, the design of a nuclear power plant involves a broad range of engineering expertise. This monograph focuses on the thermo hydraulics and neutronics of nuclear power generation and, in particular, on the interplay between these that determines the design of the reactor core. The book also has some brief description of other critical issues such as nuclear reactor safety. This necessarily includes brief descriptions of the three major accidents (Three Mile Island, Chernobyl and Fukushima) that have influenced the development of nuclear power.
Chapter 3 Dept of Mechanical Engineering, JCE, Belgaum
Page 5
Nuclear Power Plant
History of Nuclear Energy and Power Generation The neutron was discovered in 1932. The concept of a nuclear chain reaction brought about by nuclear reactions mediated by neutrons was first realized shortly thereafter, by Hungarian scientist Leó Szilárd, in 1933. Inspiration for a new type of reactor using uranium came from the discovery by Lise Meitner, Fritz Strassmann and Otto Hahn in 1938 that bombardment of uranium with neutrons (provided by an alpha-on-beryllium fusion reaction, a "neutron howitzer") produced a barium residue, which they reasoned was created by the fissioning of the uranium nuclei. On June 27, 1954, the USSR's 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 Sellafield, England was opened in 1956 with an initial capacity of 50 MW (later 200 MW). India's first research nuclear reactor and its first nuclear power plant were built with assistance from Canada. The 40 MW research reactor agreement was signed in 1956, and CIRUS achieved first criticality in 1960. This reactor was supplied to India on the assurance that it would not be used for military purposes, but without effective safeguards against such use. The technical and design information were given free of charge by Atomic Energy of Canada Limited to India. The United States and Canada terminated their assistance after the detonation of India's first nuclear explosion in 1974. Tarapur Atomic Power Station located in Tarapur, Maharashtra is the first nuclear power reactor of India. It was estabilished in October 28, 1969. It has a total capacity of 1,400MW. Fig 2. The image is a view of the Tarapur Nuclear power plant.
Chapter 4 Nuclear Reactions In nuclear physics and nuclear chemistry,
a nuclear
reaction is semantically considered to be the process in which two nuclei, or else a Dept of Mechanical Engineering, JCE, Belgaum
Page 6
Nuclear Power Plant
nucleus
of
an
particle (such
as
atom a
and
a subatomic
proton, neutron,
or
high energy electron) from outside the atom, collide to produce one or more nuclides that are different from the nuclide(s) 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 Fusion Nuclear Fission
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 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 is the process that powers active or "main sequence" stars. 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. Fig 3. A schematic representation of the equation of a nuclear fusion reaction.
Dept of Mechanical Engineering, JCE, Belgaum
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Nuclear Power Plant
Nuclear fusion is currently in its experimental phases and is not being utilized for commercial purposes due to its requirements of high initial energy and pressure so as to overcome the coulombic 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 parts (lighter nuclei). 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 4. A schematic representation of the equation of a nuclear fission reaction. Fission as encountered in the modern world is usually a deliberately produced manmade 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
Comparison between Nuclear Fusion and Nuclear Fission Nuclear Fission
Definition
Fission is the splitting of a large atom into two or more smaller ones.
Nuclear Fusion Fusion is the fusing of two or more lighter atoms into a larger one.
Natural Fission reaction does not normally occurrence of occur in nature. the process
Fusion occurs in stars, such as the sun.
Byproducts of Fission produces many highly the reaction radioactive particles.
Few radioactive particles are produced by fusion reaction
Conditions
Critical mass of the substance and high-speed neutrons are required.
Dept of Mechanical Engineering, JCE, Belgaum
High density, high temperature environment is required. Page 8
Nuclear Power Plant
Nuclear Fission Takes little energy to split two atoms Energy in a fission reaction. Requirement
Nuclear Fusion Extremely high energy is required to bring two or more protons close enough that nuclear forces overcome their electrostatic repulsion.
The energy released by fission is a million times greater than that Energy Released released in chemical reactions, but lower than the energy released by nuclear fusion.
The energy released by fusion is three to four times greater than the energy released by fission.
One class of nuclear weapon is a Nuclear weapon fission bomb, also known as an atomic bomb or atom bomb.
One class of nuclear weapon is the hydrogen bomb, which uses a fission reaction to "trigger" a fusion reaction.
Energy Fission is used in nuclear power production plants.
Fusion is an experimental technology for producing power.
Uranium is the primary fuel used in Fuel power plants.
Hydrogen isotopes (Deuterium and Tritium) are the primary fuel used in experimental fusion power plants.
Chapter 5 Components of a Nuclear Power Plant
Dept of Mechanical Engineering, JCE, Belgaum
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Nuclear Power Plant
Fig 5. The above figure shows the various components and the schematic layout of a nuclear power plant.
The Various Components of a Nuclear Power Plant are:
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 pressurized steam from that one or more steam turbine driven electrical generators. Almost all currently operating nuclear power
Dept of Mechanical Engineering, JCE, Belgaum
Page 10
Nuclear Power Plant
plants are light water reactors using ordinary water under high pressure as coolant and neutron . A neutron 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. Heavy water reactors use deuterium oxide which has similar properties to ordinary water but much lower neutron capture, allowing more thorough moderation.
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 reactors are
Pressurized Water Reactor (PWR): These constitute the majority of the reactors, the above diagram shows a PWR. The primary characteristic of PWR is a pressurizer, that is a specialized pressure vessel that stores the coolant in it and is sent into the reactor as per the requirement. In a PWR the boiler is situated in a different assembly, away from the reactor. Two fluid systems are used in a PWR, 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: BWRs are characterized by boiling water around the fuel rods in the lower portion of a primary reactor pressure vessel. A boiling water reactor uses 235U, 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 coolant itself is used to drive the turbines. The fluid used in the turbine is radioactive.
Safety Valves: In the event of an emergency, safety valves can be used to prevent pipes from bursting or the reactor from exploding. The valves are designed so that they can derive all of the supplied flow rates with little increase in pressure. In the case of the BWR, the steam is directed into the suppression chamber and condenses there. The chambers on a heat exchanger are connected to the intermediate cooling circuit.
Feedwater pump: The water level in the steam generator and nuclear reactor is controlled using the feedwater system. The feedwater pump has the task of taking the water from the condensate system, increasing the pressure and forcing it into
Dept of Mechanical Engineering, JCE, Belgaum
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Nuclear Power Plant
either the steam generators (in the case of a pressurized 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 BWRs have to be radioactively sealed so as to avoid leakage of the radioactive water.
Electric Generator: The 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.
Emergency Power Supply: Most nuclear plants require two distinct sources of offsite power feeding station service transformers that are sufficiently separated in the plant's switchyard and can receive power from multiple transmission lines. Nuclear power plants are equipped with emergency power systems to maintain safety in the event of unit shutdown and loss of offsite power. Batteries provide uninterruptible power to instrumentation, control systems, and valves.. The emergency diesel generators do not power all plant systems, only those required to shut the reactor down safely, remove decay heat from the reactor, provide emergency core cooling, and, in some plants, spent fuel pool cooling.
Chapter 6 Parts of Nuclear Reactor
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Nuclear Power Plant
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
caused
undergo
to
be
nuclear fission nuclear bombardment
and
to
produce a fission chain reaction. The fuels used are: U238, U235, U 234, UO2. Fertile materials, those which
can
be
transformed into fissile materials, cannot sustain chain reactions. When a fertile material is hit by neutrons
and
absorbs
some of them, it is converted
to
material.U238 232
are
fissile and
Th
examples
of
fertile materials used for reactor purposes.
Reactor core: This contains a number of fuel rods made of fissile material.
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: This material in the reactor core is used to moderate or to reduce the neutron speeds to a value that increases the probability of fission occurring.
Control rods: The energy inside the reactor is controlled by the control rod. These are in cylindrical or sheet form made of boron or cium. These rods can be moved in and out of the holes in the reactor core assembly.
Reflector: This completely surrounds the reactor core within the thermal shielding arrangement and helps to bounce escaping neutrons back into the core. This conserves the nuclear fuel.
Reactor vessel: It is a strong walled container housing the core of the power reactor. It contains moderate, reflector, thermal shielding and control rods.
Biological shielding: Shielding helps in giving protection from the deadly α- and βparticle radiations and γ-rays as well as neutrons given off by the process of fission within the reactor.
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 7 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 2013, India has 21 nuclear reactors in operation in 7 nuclear power plants, having an installed capacity of 5780MW and producing a total of 30,292.91 GWh of electricity while seven other reactors are under construction and are expected to generate an additional 6,100 MW. Power
Total capacity
Operator
State
Type
Units
Kaiga
NPCIL
Karnataka
PHWR
220 x 4
880
Kakrapar
NPCIL
Gujarat
PHWR
220 x 2
440
Madras
NPCIL
Tamil Nadu
PHWR
220 x 2
440
Narora
NPCIL
Uttar Pradesh
PHWR
220 x 2
440
station
(MW)
100 x 1 Rajasthan
NPCIL
Kota Rajasthan
PHWR
200 x 1
1180
220 x 4
Tarapur
NPCIL
Maharashtra
Kudankulam
NPCIL
Tamil Nadu
BWR
160 x 2
PHWR
540 x 2
VVER-1000 1000 x 1
1440
1000
Chapter 8 Dept of Mechanical Engineering, JCE, Belgaum
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Nuclear Power Plant
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 cost is less and large fuel storage facility is not needed.
There is increased reliability of operation.
Nuclear power plants are not affected by adverse weather conditions.
Nuclear power plants are well suited to meet large power demands. They give better performance at higher load factors (80-90%).
Materials expenditure on metal structures, piping, storage mechanisms are much lower for a nuclear power plant than a coal burning power plant.
It does not require large quantity of water.
The generation of electricity through nuclear energy reduces the amount of energy generated from fossil fuels (coal and oil). Less use of fossil fuels means lowering greenhouse gas emissions (CO2 and others).
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 most of the population.
The production of electric energy is continuous. A nuclear power plant is generating electricity for almost 90% of annual time. It reduces the price volatility of other fuels such as petrol.
Disadvantages of Nuclear Power Plant Initial cost of nuclear power plant is higher as compared to hydro or steam power plant.
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Nuclear power plants are not well suited for varying load conditions. Radioactive wastes if not disposed carefully may have bad effect on the health of workers and other population. Maintenance cost of the plant is high. It requires highly trained personnel to handle nuclear power plants. Nuclear power plants generate external dependence. Not many countries have uranium mines and not all the countries have nuclear technology, so they have to hire both things overseas. Nuclear power plants are objectives of terrorist organizations. Decommissioning of nuclear power stations is expensive and takes a long time. Nuclear accidents can spread 'radiation producing particles' over a wide area, This radiation harms the cells of the body which can make humans sick or even cause death. Illness can appear or strike people years after they were exposed to nuclear radiation and genetic problems can occur too. A possible type of reactor disaster is known as a meltdown. In a meltdown, the fission reaction of an atom goes out of control, which leads to a nuclear explosion releasing great amounts of radioactive particles into the environment. Chernobyl and Fukushima are the worst nuclear accidents to date causing many lives and leakage of radiation.
Chapter 9 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 extent 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. With the depletion of fuel reserves and the question of transporting fuel over long distances, nuclear power Dept of Mechanical Engineering, JCE, Belgaum
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Nuclear Power Plant
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.
Chapter 10 References An Introduction to Nuclear Power Generation by Christopher E. Bremen, California institute of technology Pasadena, California. Safety of the Indian Pressurized Water Reactors, Department of Atomic Energy,
Government of India. http://nuclear-energy.net/advantages-and-disadvantages-of-nuclear-energy.html http://en.wikipedia.org/wiki/Nuclear_reaction http://en.wikipedia.org/wiki/Nuclear_fission http://en.wikipedia.org/wiki/Nuclear_power_in_India http://en.wikipedia.org/wiki/Nuclear_reactor
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http://en.wikipedia.org/wiki/Nuclear_fission http://en.wikipedia.org/wiki/Nuclear_power http://en.wikipedia.org/wiki/Nuclear_power_plant http://www.cyberphysics.co.uk/topics/nuclear/advantages_disadvantages_nuclear_ power.htm
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