nuclear powerplant seminar report

Nuclear Power Plant 2017

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.


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


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.


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.


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]


CHAPTER 4

COMPONENTS 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 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


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 reactors are:--

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


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.


CHAPTER 5Parts 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.


4. Reactor vessel :- It is a strong walled container housing the core of the power reactor. It contains moderate, reflector, thermal shielding and control rods.

5. Coola nt :- 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.


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


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%).

It does 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 most of 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 cost of the plant is high.

It requires highly trained personnel to handle nuclear power plants.

Nuclear power plants are objectives of terrorist organizations.

Decommissioning of nuclear power stations is expensive and takes a long

time.


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”


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

nuclear powerplant seminar report

Education