The document is a training report submitted by Rohit Chouhan after completing a 45-day industrial training program at the Nuclear Power Corporation of India Limited (NPCIL) Rajasthan Atomic Power Station. It provides an overview of NPCIL, including its mission to develop nuclear power as a clean and sustainable source of electricity. It describes the layout and key facilities at the Rajasthan Atomic Power Station, and discusses the principles of nuclear fission and power generation. The report aims to document the knowledge gained during the student's training placement.

1. A
Practical Training & Industrial Visit Report
On
NUCLEAR POWER CORPORATION OF INDIA LIMITED
At
RAJASTHAN ATOMIC POWER STATION, RR SITE
Submitted in partial fulfillment of the requirements for the award of
the degree of
Bachelor of Technology
in
Electrical Engineering
(Session2019-2020)
Submitted to Submitted by
Prof. ( Dr.) Babitakumari Jain Rohit Chouhan
(FacultyCoordinator-Industrial Training) PCE16EE135
DEPARTMENT OF ELECTRICAL ENGINEERING
POORNIMA COLLEGE OF ENGINEERING, JAIPUR
RAJASTHAN TECHNICAL UNIVERSITY, KOTA
July 2019

2. DECLARATION
I hereby declare that the work which is being presented in the Practical Training & Industrial
visit report titled “Nuclear Corporation Of India Limited” in partial fulfillment for the award
of the Degree of Bachelor of Engineering in Electrical Engineering and submitted to the
Department of Electrical Engineering, Poornima College of Engineering, Jaipur, is an
authentic record of my own work carried out at NPCIL, RR Site during the session 2019-20
(Even Semester).
I have not submitted the matter presented in this report anywhere for the award of any other
Degree.
Signature of the Student with Name & Reg. No.:
Place: ________
Date: _________
Enclosed: Training Certificate from Company
ii

3. iii

4. DEPARTMENT OF ELECTRICAL ENGINEERING
Date:
CERTIFICATE
This is to certify that Practical Training & Industrial Visit report titled Wires and
Cables has been submitted by Rohit Chouhan PCE16EE135 in partial fulfillment for
the award of the Degree of Bachelor of Technology in Electrical Engineering during
the session 2019-20. The Practical Training & Industrial visit work is found satisfactory
and approved for submission.
Dr. Babita Kumari Jain Dr. Amit Shrivastava
Professor, EE Professor-EE
(Faculty Incharge - Industrial Training) Coordinator-Industrial Training
Dr. Virendra Sangtani
HoD, EE
Date: ________
Place: Jaipur
iv

5. V
ACKNOWLEDGEMENT
I have undergone an Industrial Training which was meticulously planned and
guided at every stage so that it became a life time experience formed. This
could not be realized without the help from numerous sources and people in
the Poornima College of Engineering and Nuclear power plant.
First of all I would like to pay my gratitude to Mr Omprakash Yadav,
Manager, Khandelwal Industries and his team for guiding me during my
training.
I would like to take this opportunity to show my gratitude to wards Prof.
(Dr.) Babita Kumari Jain(Coordinator Practical Training and Industrial Visit)
who helped me in successful completion of my Industrial Training. He has
been a guide, motivator & source of inspiration for us to carry out the
necessary proceedings for completing this training and related activities
successfully.
I am also very grateful to Dr.Virendra Sangtani HoD, Electrical
Engineering for his kind support.
I am thankful to Prof.(Dr.) MaheshM. Bundele, Principal and Director,
Poornima College of Engineering, for guiding and inspiring to carry out the
necessary proceedings for completing this training and related activities
successfully.
I am greatful of Mr. Pankaj Dembla, Vice Principal and Ms. Dipti Lodha,
T.P.O, Poornima College of Engineering for providing us a platform to carry
out this training successfully.
I would also like to express my heart felt appreciation to my parents and all
of my friends for help me to complete this training successfully.
Rohit Chouhan

6. VI
TABLE OF CONTENTS
CHAPTER
NO.
PARTICULARS PAGE NO.
Title Page I
Candidate’s Declaration II
Certificate by the Company III
Certificate by the Department IV
Acknowledgment V
Table of Contents VI
List of Tables 1
List of Figures 1
Abstract 2
1 Introduction
1.1 Background of the Company
1.2 Contribution and production
1.3 Value and Objective
1.4 View of different Stations
1.5 Nuclear Power
1.6 Principle
3
3
3
5
6
8
9
2 Training Description
2.1 NPCIL
2.2 RAPS
2.3 Three stages of NPCIL
2.4 PHWR
2.5 Description of standard Indian PHWR
2.6 Reactor
2.7 Radioactive Waste Management
2.8 Safety classification of systems
2.9 Safety
2.10 RAPPCOF Cobalt Facility
2.11 Fire Section
2.13 Substation
2.14 Substation Parts and Equipment
2.15 Switchyard
2.16 Challenges and opportunities
2.17 Future of Industry
10
11
11
15
16
22
26
27
28
31
32
33
33
34
35
36
36
3 Conclusion
3.1 Introduction
3.2 References
39
39
40

7. LIST OF TABLES
TABLE
NO.
TITLE PAGE
NO.
2.1 Salient features of RAPS-3&4 12
2.2 Operational Nuclear Power Plants 13
2.3 Proposed Nuclear Power Plants Sites India 15
2.11 Classes of fire 34
2.12 ESL Lab Survey 35
LIST OF FIGURES
FIGURE
NO.
TITLE PAGE
NO.
1.1 Electricity producing sources in India 4
1.3(a) RAPS 1&2 6
1.3(b) RAPS 3&4 7
1.3(c) RAPS 5&6 7
1.4 NPCIL Power Plants in India 8
2.5.1 Plant Layout 16
2.5.2 Reactor Building 17
2.5.3 Control Mechanism 19
2.5.5 Fuel Bundle 19
2.5.7 Nuclear Power Plant 21
2.6 Reactor cut-away 23
2.11 Fire Triangle 33
2.15 Switchyard 38
2.15.2 Vacuum Circuit Breakers 40
2.15.3 Lightning Surges 41
2.15.7 Capacitor Bank 43

8. 2
ABSTRACT
As we know that an engineer has to serve an industry, for that one must be aware of industrial
environment, their management, problems and the way of working out their solutions at the
industry. After the completion of the course an engineer must have knowledge of interrelation
between the theory and the practical. For this, one must be familiar with the practical knowledge
with theory aspects.
To aware with practical knowledge the engineering courses provide 45 days industrial training
for 3rd year students where we get the opportunity to get theory applying for running the various
process and production in the industry
.I have been lucky enough to get a chance for undergoing this training at RAJASTHAN
ATOMIC POWER STATION. It is a constituent of board of NPCIL. This report has been
prepared on the basis of knowledge acquired by me during my training period of 45 days at the
plant.

9. 3
CHAPTER 1
INTRODUCTION
1.1 BACKGROUND OF COMPANY
Considering the current population growth which has already crossed 100 crores in the 21st
century and improvements in standard of living of the forth coming generations, there will be
a large increase in the demand of electrical energy, particularly from clean, green and safe
energy sources. The electricity will play a vital role in sustainable development of the country.
The exploration of natural resources for generation of electricity has been an evolutionary
process. As day by day the conventional resources of energy are lasting, man is searching for
new energy sources, which can serve for long period.
Among all the available conventional and non-conventional energy sources, the nuclear energy
in the most efficient abundantly available, sustainable and cost effective energy source. It does
not emit gases that cause global warming, ozone layer depletion and rain.
The energy needs of a country cannot be met from single source. Hydroelectric power stations
produces cheap power but need a thermal backing to increase the firm capacity, the coal
reserves of the world are fast depleting. Thus nuclear power is the only source, which can
supply the future energy demands of the world.
1.2 CONTRIBUTIONAND PRODUCTION
India's Nuclear power developments are under the purview of the Nuclear Power Corporation
of India, a government-owned entity under the Department of Atomic Energy India. The
corporation is responsible for designing, constructing, and operating nuclear-power plants. In
1995 there were nine operational plants with a potential total capacity of 1,800 megawatts,
about 3 percent of India's total power generation. And till now there are 22 nuclear power
reactors which NPCIL operate with a capacity of 6780 MWe at 8 sites across the nation.
Currently, NPCIL is building 4 more reactors, which will add 2800 MWe of electrical power.
In addition, a 500 MWe Prototype Fast Breeder Reactor (PFBR) is being constructed at
Kalpakkam by Bharatiya Nabhikya Vidyut Nigam Limited (BHAVINI). There are four units
each in Tarapur(Maharashtra) & Kaiga (Karnataka), six units in Rawatbhata (Rajasthan), two
in Kalpakkam (Tamil Nadu) and two in Narora (Uttar Pradesh) two units in Kakrapur (Gujarat)

10. 4
and two units in Kudankulam(Tamil Nadu). These nuclear power plants produce environment
friendly electricity.
Fig 1.1 Electricity producing sources in India
1.3 VISION, MISSION, VALUES AND OBJECTIVE
1.3.1 VISION
“To be globally proficient in nuclear power technology, contributing towards long term energy
security of the country.”
1.3.2MISSION

11. 5
The Mission of the Company is ‘To develop nuclear power technology and to produce nuclear
power as a safe, environmentally benign and economically viable source of electrical energy
to meet the increasing electricity needs of the country'.
1.3.3 CORE VALUES
We treasure our Values
 Safety – Safety is an overriding priority in our all activities.
 Ethics – Upholding highest ethical standards, with honor, through integrity and mutual
trust.
 Excellence –Continual improvement through learning, self-assessment and setting
higher benchmarks.
 Care – Care and compassion for people and protection of environment.
1.3.4 OBJECTIVES
 To maximizes the power generation and profitability from nuclear power stations with
the motto ‘safety first and production next’.
 To increase nuclear power generation capacity in the country, consistent with available
resources in a safe, economical and rapid manner, in keeping with the growth of energy
demand in the country.
 To continue and strengthen QA activities relating to nuclear power program within the
organization and those associated with it.
 To develop personnel at all levels through an appropriate Human Resources
Development (HRD) program in the organization with a view to further improve their
skills and performance consistent with the high technology.
 To continue and strengthen the environmental protection measures relating to nuclear
power generation.
 To continue and strengthen the neighborhood welfare program /CSR activities for
achieving inclusive growth of surrounding population.
 To share appropriate technological skills and expertise at national and international
levels.
 To bring about modernization and technological innovation in activities.
 To coordinate and endeavor to keep the sustained association with the other units of
DAE.
1.4 VIEW OF DIFFERENT STATIONS
1.4.1 RAJASTHAN ATOMIC POWER STATION-1&2

12. 6
Fig 1.4 (a) RAPS 1&2
1.4.2 RAJASTHAN ATOMIC POWER STATION-3&4
1.4 (b) RAPS 3&4

13. 7
1.4.3 RAJASTHAN ATOMIC POWER PROJECT-5&6
Fig 1.4(b) RAPS 5&6
1.5 NUCLEAR POWER – PROVIDING A CLEAN AND SUSTAINABLE
FUTURE
Environment friendly electricity is the hallmark of nuclear energy. Clean, carbon-emission-
free power produced by nuclear power plants helps protect the earth’s environment by reducing
the march of global warming. Apart from producing CO2 free electricity, nuclear power also
does not entail emission of SO2 or NO2,so it, does not contribute to acid rain, thereby protecting
lakes, rivers and soil from turning acidic. The radiation from a nuclear power plant is a
negligible small fraction of the natural background radiation i.e. radiation present in nature.
With these clean and green attributes, nuclear power is not only harmonious to nature but also
a truly sustainable source of power that can serve the long term electricity needs of a fast
growing nation like ours.

14. 8
Fig 1.5 NPCIL POWER PLANTS IN INDIA
1.6 PRINCIPLE OF NUCLEAR REACTION
When a heavy nucleus splits into smaller nuclei, an amount of its binding energy (energy that
bounds the neutrons & protons within the nucleus) is released. The amount of energy released
can be calculated using Einstein’s famous Mass-Energy equivalence equation E=mc2. This
breaking up of a heavy nucleus accompanied with a release of enormous amount of energy in
the form of heat & light is known as ‘nuclear fission’.This nuclear fission is the basic principle
behind any nuclear reactor.
Natural Uranium has three isotopes: - U-233, U-235 & U-238.The percentages of these
isotopes in the naturally occurring uranium are: -
1. U-233 -- less than 0.02 %
2. U-235 -- 0.7 %
3. U-238 -- 99.28 %

15. 9
The less abundant U-235 is the fuel for RAPS-3&4 type of reactor. When a thermal or slow
moving neutron strikes a U-235 atom, it gets split into two or more nuclei. This splitting of
nuclei is accompanied by a release of huge amount of energy and releases two or three neutrons,
which can further hit two or three nuclei and which in turn release more energy and further sets
of neutrons. Attainment of self-sustained stage of splitting of Uranium atoms is called as
‘chain-reaction’.
92U 235 + 0n138Sr90 + 54Xe144 + 2 0n1 +  + Q
There is a particular size of fissionable material for which the neutron production byfission is
exactly balanced by leakage & absorption. This is called the ‘Critical size’ at which the chain
reaction is self-sustaining.

16. 10
CHAPTER 2
TRAINING DESCRIPTION
2.1 NUCLEAR POWER CORPORATION OF INDIA LIMITED
2.1.1 PLANT LAYOUTOF RAPS 3&4
RAPS 3&4 plant layout has been developed on the basis of two unit modules of 220MWe and
takes care of current international safety standards. The overall plant layouts are for a twin unit
complex. The principal features of the layout are:-
1) The layout is based on the concept of in dependent operation of each unit.
2) Mirror image is avoided to the maximum extent possible to retain uniformity in layout.
3) All safety related systems and components are grouped together.
4) Reactor auxiliary building is located near to the reactor building to avoid long piping
lengths.
5) Control room & control equipment room in this building are so laid out as to cater for
unitized operation.
6) Emergency power system such as DG & batteries are provided separately in safety related
structures.
7) Physical protection scheme to protect against industrial sabotage & external or internal
malevolent ad ions.
2.1.2 SITE SELECTION
Government of India has constituted a site selection committee (SSC) consisting of members
representing different disciplines and agencies. The main objective in sitting Nuclear Power
Plants from the point of view of nuclear safety is to be able to construct and operate Nuclear
Power Plants safely & too provide protection to the public against radiological impact resulting
from accidental releases of radioactive material as well as release of such materials during
normal operation of the plant. Hence the basic criteria for selection of a site for the location of
a nuclear power plant shall be to ensure that the site plant interaction will not introduce any
radiological risk or others of an unacceptable magnitude.
The criteria that are followed for site selection are:
1 Regional energy resources & load demands.
2 Land availability & land for locating plant structures.
3 Accessibility.
4 Construction facility.
5 Cooling water availability.

17. 11
6 Foundation conditions – Geology of substrata, its bearing capacity & ground water table.
7 Flooding.
8 Natural & Man-induced events.
9 Population.
10 Radiological impact.
11 Meteorological & air releases.
12 Hydrology & liquid waste.
13 Electrical system: Power evacuation, stability, reliable startup and construction power.
14 Availability of transport facility for transportation of heavy equipment’s.
15 Radioactive waste disposal facility.
2.2 RAJASTHAN ATOMIC POWER STATION:
This station is situated on the right bank of RANA PRATAP SAGAR lake formed between
two dams, Gandhi Sagar dam at upstream &RanaPratapSagar dam at downstream of Chambal
river. The station is 64 Km from Kota.
The “RAJASTHAN ATOMIC POWER STATION” is owned by Nuclear Power Corporation
of India Limited (NPCIL) under the supports of Department of Atomic Energy. The main aim
of NPCIL is the development of nuclear energy for economic generation of power and
alternative source of electric power when due source of time conventional sources (Hydro &
Thermal) will be exhausted in the country.
The site consists of six identical reactors of 220 MW rating each, named as RAPS-1&2,
RAPS-3&4, RAPS-5&6 and two constructing reactors of 700 MW named as RAPP-7&8. The
RAPS-1&2 and RAPS-3&4 stations deliver electricity at 220 KV and RAPS-5&6 deliver
electricity at 400 KV to the Northern Grid. Each station has two units of Pressurized Heavy
Water Reactor (PHWR) type reactors. This type is characterized by: -
(a) A horizontal pressure tube reactor.
(b) Natural Uranium fuel.
(c) Low pressure heavy water as Moderator.
(d) High pressure heavy water as Coolant.
(e) On power by-directional re-fueling.
Capacity : 2 × 220 MWe
Energy output : (a) Thermal: 756 MW (Calandria Core)
(b) Electrical: 220 MW (Generator)
Efficiency : 29.61 % overall
Type of Reactor : PHWR
Fuel : Natural Uranium as Uranium Di-Oxide (UO2)

18. 12
Coolant : Heavy water
Moderator : Heavy water
Steam :  Quality: Saturated steam @ 40 Kg/cm2
 Quantity: 1300 Ton/hr.
 Wetness Fraction: 0.10 to 0.11
Turbine : Horizontal Impulse reaction tandem compounded
Steam Generator : 4, non-mixing type integral U-type bundle in a shell generating
0.26 % wet saturated steam at 41.8 Kg/sq. cm. and 250.30 C
temperature.
Reactor Regulatory System:
Regulating rods : 4, with elements containing Cobalt Pellets/Slugs used for
regulation, setback and flux tilt control.
Absorber rods : 8, with elements containing Cobalt Pellets/Slugs for Xenon over
side, reactivity control and addition of positive reactivity.
Shim rods : 2, of Cadmium sandwiched in SS tubes for addition of negative
reactivity and reactor setback.
Reactor Protection System:
Fast acting primary shut
down system
: 14, vertical rods of Cadmium sandwiched in SS tubes to
trip the reactor.
Fast acting secondary shut
down system
: 12, liquid poison injection shut-off tubes containing
Lithium Pentaborate solution in Heavy water.
Liquid poison injection
system
: Bulk addition mode of Boron solution in Moderator for
prolonged shut down.
Automatic liquid poison
addition system
: Control addition mode of Boron solution in moderator to
augment the capacity of shim rods.
Table No. 2.1-Salient features of RAPS-3&4
Station Rated Capacity (MWe) Year of Criticality

19. 13
TAPS-1&2 2 x 160 1969
RAPS-1 100 1972
RAPS-2 200 1980
RAPS-3 235 1999
RAPS-4 235 2000
RAPS-5 235 2010
RAPS-6 235 2010
MAPS-1 220 1983
MAPS-2 220 1985
NAPS-1 220 1989
NAPS-2 220 1991
KAPP-1 220 1992
KAPP-2 220 1993
KAIGA-1 235 1996
KAIGA-2 235 1996
KAIGA-3 235 2010
KAIGA-4 235 2011
TAPS-3 540 2006
TAPP-4 540 2005
KKNPP Unit-1 1000 2014
KKNPP Unit-2 1000 Light Water Reactor under construction
MADRAS 500 Fast Breeder Reactor under construction
KAPP-3&4 700X2 Pressurized Heavy Water Reactor
RAPP-7&8 700X2 Pressurized Heavy Water Reactor
Table No. 2.2- List of various operational Nuclear Power Plants in India

20. 14
Project Rated Capacity (MWe) Type of Reactor
Jetapur (Maharastra) 1000X4 Light Water Reactor
Gorakhpur (Haryana) 1000X2 Light Water Reactor
Chutka (MP) 1000X2 Light Water Reactor
Bhimpur (MP) 1000X2 Light Water Reactor
Table No. 2.3-List of proposed sites for Nuclear Power Plants in India
2.3 THE THREESTAGESOF OUR NUCLEAR POWER PROGRAMME
# STAGE 1 = This stage envisages construction of pressurized heavy water reactor (PHWR)
using natural uranium as fuel and heavy water as moderator. Spent fuel from these reactors is
reprocessed to obtain plutonium.
# STAGE 2 = This stage envisages on the construction of fast breeder reactors (FBR) fuelled
by plutonium & depleted U produced in stage1. These reactors would also breed U233 from th
orium.
# STAGE 3 = This stage would comprise power reactors using U233 – thorium as fuel, which
is used as a blanket in these types of reactors.
2.4 WHY PHWR?
THE PHWR WAS CHOSEN DUE TO THE FOLLOWING:
# It uses natural uranium as fuel. Use of natural uranium available in India helps to cut heavy
investments on enrichment that are capital intensive.
# Uranium requirement is the lowest & plutonium production is the highest.
# The infrastructure available in the country is suitable for undertaking manufacture of the eq
uipment. The short- term goal of the program was to complement the generation of electricity
at locations away from coalmines. The long-term policy is based on recycling nuclear fuel &
harnessing the available thorium resources to meet country’s long- term energy demand and s
ecurity.
2.5 DESCRIPTION OF STANDARD INDIAN PHWR :
2.5.1 LAYOUT

21. 15
The nuclear power stations in India are generally planned as two units modules, sharing com
mon facilities Such as service building, spent fuel storage bay& other auxiliaries like heavy w
ater upgrading, waste management facilities etc. Separate safety related systems & componen
t are however provided for each unit. Such an arrangement retains independence for safe oper
ation of each unit & simultaneously permits optimum use of space, finance & construction ti
me.
Fig 2.5.1 PLANT LAYOUT
The layout for a typical 220MW station consists of two reactor building, active service buildi
ng including spent fuel bay, safety related electrical, control buildings and the two turbine bui
ldings. Orienting turbine building radial to the reactor building provides protection from the e
ffect of turbine missiles. Other safety related building & structures are also located has not to
fall in the trajectory of missiles generated from the turbine. The building and structures have
also been physically separated on the basis of their seismic classification. Sectional views of t
he reactor building are depicting general layout inside the reactor building.
2.5.2REACTOR

22. 16
In concept, the Indian pressurized heavy water reactor is a pressure tube type reactor using
heavy water moderator, heavy water coolant &natural uranium dioxide fuel. The reactor as
shown in the fig, consists primarily of calandria a horizontal cylindrical vessel. It is penetrated
by a large number of zircaloy pressure tubes (306 for 235MWe reactor), arranged in a square
lattice. These pressure tubes also refer as coolant channels; contain the fuel & hot high –
pressure heavy water coolant.
Fig 2.5.2 REACTOR BUILDING
The pressure tubes are attached to the alloy steel and fitting assemblies at either end by special
role expended joints. A typical pressure tube assembly is shown figure. End – shields are the
integral parts of the calandria and are provided at each end of the calandria to attenuate the
radiation emerging from the reactor, permitting access to the fuelling machine vaults when the
reactor is shutdown. The end fittings are supported in the end shield lattice tubes through
bearing, which permit their sliding. The calandria is housed in a concrete vault, which is lined
with zinc metallised carbon steel & filled with chemically treated demineralised light water for
shielding purposes. The end shields are supported in openings vault wall, and form part of the

23. 17
vault enclosure at these openings. Removable shield plugs fitted in the end fittings provide
axial shielding to individual coolant channels.
2.5.3 REACTIVITY CONTROL MECHANISMS:
Due to the use of natural uranium fuel & on-load refueling, the PHWR’s do not need a large
excess reactivity. Correspondingly the devices required for control of reactivity in the core
need not have large reactivity worth’s. Standard reactors designs are provided with four
systems for reactivity control, viz.
1) Regulating rods
2) Shim rods
3) Adjuster rods for xenon override
4) Natural boron addition in the moderator to compensate for the excess reactivity
in
a fresh core &for absence of xenon after a long shutdown.
The reactivity control devices are installed in the low-pressure moderator region & so they are
not subjected to potentially severe hydraulic & thermal forces in the event of postulated
accidents. Furthermore, the relatively spacious core lattice of PHWR allows sufficient
locations to obtain complete separation between control & protective functions. The regulating
systems are thus fully independent with it’s own power supplies, instrumentations & triplicated
control channels. Cobalt and stainless steel absorber elements have been utilized in the
reactivity control mechanisms.
For 220MW standardized design, two diverse, fast acting & independent shutdown systems
have been adopted. This feature provides a high degree of assurance that plant transients
requiring prompt shutdown of the reactor will be terminated safely.
The primary shutdown system consists of 14 mechanical shut off rods of cadmium sandwiched
in stainless steel &makes the reactor sub-critical in less than 2 secs. Fail-safe features like
gravity fall &spring assistance have been incorporated in design if mechanical shut off rods.
The second shutdown system, which is also fast acting, comprises 12 liquid poison tubes,
which are filled with lithium penta borate solution under helium pressure. The trip signal
actuates a combination of fast acting valves and causes poison to be injected simultaneously in
12 interstitial liquid poison tubes of calandria.
Fig 2.5.3 CONTROL MECHNASIM
2.5.4 FUEL DESIGN
Fuel assemblies in the reactor are short length (half metre long) fuel bundles. Twelve of such
bundles are located in each fuel channel. The basic fuel material is in the form of natural
uranium dioxide a pellet, sheathed & sealed in thin zircaloy tubes.

24. 18
Fig 2.5.5 FUEL BUNDLE
Welding them to end plates to form fuel bundles assembles these tubes. Figure 5 shows the 19-
element fuel bundle being used in 220 MWe PHWRs.
2.5.5 FUEL HANDLING:
On power fuelling is a feature of all PHWRs, which have very low excess reactivity. In this
type of reactor, refueling to compensate for fuel depletion & for over all flux shaping to give
optimum power distribution is carried out with the help of 2 fueling machines, which work in
conjunction with each other on the opposite ends of a channel. One of the machines is used to
fuel the channel while the other one accepts the spent fuel bundles. In addition, the fueling
machines facilitate removal of failed fuel bundles. Each fuelling machine is mounted on a
bridge & column assembly. Various mechanisms provided along tri- directional movement (X,
Y&Z direction) of fueling machine head and make it possible to align it accurately with respect
to channels. Various mechanisms have been provided which enables clamping of fueling
machine head to the end fitting, opening & closing of the respective seal plugs, shield plugs
&perform various fuelling operations i.e. receiving new fuel in the magazine from fuel transfer
system, sending spent fuel from magazine to shuttle transfer station, from shuttle transfer
station to inspection bay & from inspection bay to spent fuel storage bay.
2.5.6 MODERATOR SYSTEM:
The heavy water moderator is circulated through the calandria by aid of a low temperature &
low – pressure moderator system. This system circulates the moderator through two heat
exchangers, which remove heat dissipated by high – energy neutrons during the process of
moderation. The cooled moderator is returned to the calandria via. Moderator inlet nozzles.
The high chemical purity and low radioactivity level of the moderator are maintained through
moderator purification system. The purification system consists of stainless steel Ion –
Exchange Hoppers, eight numbers in 220MWe contains nuclear grade, mixed Ion - Exchange
resin (80% anion & 20% cation resins) .the purification system is also utilized for removable
of chemical shim, boron to effect start –up of reactor Helium is used as a cover – gas over the
heavy water in calandria. The concentration deuterium in this cover- gas is control led by
circulating it using a sealed blower and passing through the recombination containing catalyst
Alumina – coated with 0.3% Palladium.
2.5.7 PRIMARY HEAT TRANSPORT (PHT) SYSTEM:
The system, which circulates pressure coolant through the fuel channels to remove the heat
generated in fuel, is referred as Primary Heat Transport System. The major components of this
system are the reactor fuel channels, feeders, two reactor inlet headers, two reactor outlet
headers, four pumps &interconnecting pipes & valves. The headers steam generators & pumps
are located above the reactor and are arranged in two symmetrical banks at either end of the
reactor. The headers are connected to fuel channels through individual feeder pipes. Figure
depicts schematically the relative layout of major equipment in one bank of the PHT system

25. 19
.the coolant circulation is mentioned at all times during reactor operation, shutdown &
maintenance.
Fig 2.5.7 NUCLEAR POWER PLANT
2.5.8 FUEL
The use of natural uranium dioxide fuel with its low content of fissile material (0.72% U-235)
precludes the possibility of a reactivity accident during fuel handling or storage. Also, in the
core there would no significant increase in the reactivity, in the ever of any mishaps causing
redistribution of the fuel by lattice distortion or otherwise.
The thermal characteristics namely the low thermal conductivity and high specific heat oh UO2
permit almost all the heat generated in a fast power transient to be initially absorbed in the fuel.
Furthermore, high melting point of UO2 permits several full power seconds of heat to be safely
absorbed above that contained at normal power.
Most of the fission products remain bound in the UO2 matrix and may get released slowly
only at temperatures considerably higher than the normal operating temperatures. Also on the

26. 20
account of the uranium dioxide being chemically inert to the water coolant medium, the
defected fuel releases limited amount of radioactivity to the primary coolant system.
The use of 12 short length fuel bundles per channels in a PHWR, rather than full – length
elements covering the whole length of the core, subdivides the escapable radioactive facility in
PHWR has also the singular advantage of allowing the defected fuel to be replaced by fresh
fuel at any time.
The thin Zircalloy – 2/4 cladding used in fuel elements is designed to collapse under coolant
pressure on to the fuel pellets. This feature permits high pellet - clad gap conductance resulting
in lower fuel temperatures & consequently lower fission gas release from the UO2 matrix into
pellet – clad gap.
2.6 REACTOR AUXILIARIES
2.6.1 END SHIELD COOLING SYSTEM
There are two End Shields provided at both the ends of calandria performing the following
functions.
(i) Providing supports for calandria tubes and pressure tubes.
(ii) Provides radiation and thermal shielding for fuelling machine vaults so that the fuelling
machine vaults can be accessible during shutdown.
Heat is removed from the end shields to moderator and calandria vault water. However the
bulk of the heat is removed by End shield cooling system.
The basic requirements of the end shield cooling system are:
 To maintain calaridria side tube sheet (CSTS) of end shield at an average temperature
of 67deg centigrade.
 To maintain temperature difference between various parts of end shield within
permissible limits.
 To avoid stagnant pockets of coolant, in end shield, this could cause corrosion
problems.
 To avoid overheating and hot spots which could lead to damage of end shield.
 To provide venting of end shield for uniform shielding in accessible and S/D accessible
areas.
The End Shield Cooling System is a closed loop system consisting of end shields, circulating
pumps, and heat exchangers. An auxiliary loop exists for the control of water chemistry.

27. 21
(Almost 50% of the heat load is from PHT).
Fig 2.6 REACTOR CUT-AWAY
There are two end shields where the heat is generated due to radiation and conduction from
other reactors component i.e. End fittings, Feeders, convection and radiation across insulation
gaps. A total of 1.4 MW of heat load exists for each end shield. This heat is removed by
circulation of demineralised water through the End Shields. The End Shields consist of two
compartments called front and rear compartments. DM Water (900 LPM) enters the front
compartment (the compartment facing the calandria) from five inlets at the top. Front
Compartment is further divided into five separate columns. DM Water passes through these
columns at a velocity of 37.7 cm/sec and flows into the annulus space between the outer and
inner shells of End shield.
2.6.2 CALANDRIA VAULT COOLING SYSTEM
In RAPS calandria vault (the space between the calandria and steel lined structural wall) is full
of demineralised (DM) water. DM water filled calandria vault provides radiation, biological
and thermal shielding, and also acts as heat sink in case of serious contingency. Filling of
calandria vault with DM water eliminated Argon-41 activity of earlier Indian PHWRs which
had air filled calandria vaults (RAPS 1&2 AND MAPS). This drastically cuts the exposure of
public in the vicinity of Indian Nuclear Power Plants.
The dimensions of the calandria vault are such that a minimum water thickness of 1.35 meters
is ensured between the calandria and concrete vault.This ensures adequate shielding.
2.6.3 FUNCTIONS OF THE CALANDRIA VAULT COOLING SYSTEM
The functions of the calandria vault cooling system are as follows:
i) To remove heat generated in vault water.
ii) To provide thermal shielding and biological shield under all condition.

28. 22
iii) To maintain uniform temperature in the vault structure below permissible limit under all
condition.
iv) Provide an environment compatible with the material used for components within vault.
Heat appearing in calandria vault water is removed by a closed loop cooling system. Water at
42.5deg cen. is distributed through perforated header laid out in the bottom of the vault and
warm water at 46.2deg cen. leaves the vault through header at the top.
2.6.4 VAPOUR SUPPRESSION SYSTEM
Large pool of water (2200M3, 2.4m deep) at the basement of the reactor building is provided
to limit peak pressure inside volume Vi during LOCA (Loss of coolant accident) or MSLB
(Main steam line break) by condensing high enthalpy steam. Volume Vi is connected to the
suppression pool via an annular space between the RB structure wall and inner containment
wall.
The suppression pool is provided with a re circulation system to protect against corrosion and
biological growth.
2.6.5 ANNULUS GAS MONITORING SYSTEM
The annulus gas monitoring system of RAPP 3&4 provides a means of monitoring the leakage
(if any) of heavy water either from PHT or from moderator system due to failure of coolant
tube calandria tube or rolled joints. It is a closed loop recirculating system which maintains
flow of C02 gas through the annulus gap between coolant tithe and calandria tithe. Apart from
leak detection, the annulus gas also acts as a thermal barrier, separating the hot high pressure
coolant tubes and the comparatively cooler low pressure calandria tubes. By reducing heat
transfer between coolant tube and calandria tube, heat removal requirements from moderator
system are minimized as well as the reduction in loss of heat from PHT system. In addition,
the annulus gas minimizes corrosion and hydrides formation in the coolant tubes or in the garter
spring spacers by providing a dry 02 doped gas atmosphere in the annulus.
2.6.6 LIQUID POISON INJECTION SYSTEM
For prolonged shutdown of reactor (1) for maintenance jobs or (ii) when reactor has tripped on
reactivity transient which do not permit restart of reactor within poison override time, LPIS is
actuated so that sub criticality margin is maintained under all conditions. LPIS adds a bulk
amount of liquid poison directly to the moderator to keep the reactor under shutdown state for
prolonged duration. This is an independent process system and is the replacement of (i) ALPAS
bulk addition mode (at NAPP and KAPP) which required moderator circulation and (ii) gravity
addition of boron (GRAB)
The LPIS works on pneumatic pressurization of boron solution by helium. The system consists
of poison tank and helium tank. When a command for poison addition is received the pressure
balance valves and siphon break valves close and injection valves open. This causes the
pressurization of poison tank by helium stored in helium tank. This in turn causes injection of
boron poison directly into the moderator through two nozzles in calandria at 75%FT level.
2.6.7 D2O EVAPORATION AND CLEAN UP SYSTEM
D20 evaporation and clean up system purifies downgraded heavy water to a level which is not
harmful to heavy water upgrading system by removing all the impurities. The heavy water
collected from various leakages and spills contains a number of impurities which normally
arise from Surface from which D20 is collected. Corrosion products produced inside the reactor
D20 system.Products resulting from radiolytic process. Organic material from ion exchange
resin dueteration and breakdown.
D20 evaporation and cleanup system is designed to clean the downgraded heavy water
chemically so that it can be fed to upgrading plant. Cleanup system comprises of oil water
separation stage, filtration stage and ion exchange stage.
2.6.8 HEAVY WATER UPGRADING SYSTEM
Heavy water is used as moderator and primary heat transport fluids in PHWRs. Heavy water
is highly hygroscopic. Hence it leaks from the system, it gets downgraded on exposure to
atmosphere. Such leaked heavy water collected from various points in the reactor is to be

29. 23
upgraded before use in reactor, since the isotopic purity required for moderator heavy water is
as maximum as achievable.
2.6.9 HEAVY WATER VAPOUR RECOVERY SYSTEM
Heavy water vapour arising out of spills/leakages from primary heat transport, moderator and
fuelling machine circuits is recovered from building atmosphere by adsorption on molecular
sieve beds. Vapour recovery system is an important feature of the station heavy water
management schemes. Following are the criteria for design and operation of vapour recovery
system—
 To effect economy in reactor operating costs by efficient recovery of heavy water that
escapes into the building atmosphere.
 To minimise heavy water loss and tritium loss and tritium release through stack.
 To minimise tritium activity levels in various areas of the reactor building.
 To keep the volume V1 area under negative pressure with respect to volume V2 area
for preventing the spread of activity from volume V1 to volume V2.
2.7 RADIOACTIVE WASTE MANAGEMENT
Operation of a nuclear facility like nuclear power station inevitably leads to the production of
low level radioactive wastes which are collected segregated to select best processing method,
and conditioned for either interim site storage or for disposal. The design of facilities is such
that the average public exposure from radioactive materials at the exclusion boundary is a small
fraction of the recommended AERB limits.
2.7.1 SOLID RADIOACTIVE WASTE MANAGEMENT SYSTEM :
Solid radioactive waste in segregated into three general categories based on contact dose.
Category-1 Waste: Largely originates -Protective clothing .Contaminated metal parts and
miscellaneous items. As it can contain no radioactivity.This waste will be collected in
unshielded standard drums.
Category-II & III Waste:
Filter cartridges and ion exchanges resins. Typically this waste has an unshielded radiation
field greater than 1 R/hr. on contact. These require additional shielding and greater
precautions than for category-I during transportation, handling and storage operation.
2.7.2 LIQUID RADIOACTIVE WASTE MANAGEMENT SYSTEM:
The Liquid Radioactive Waste Management System provides for collection, storage, sampling
and necessary treatment and dispersal of any liquid waste produced by the station. The system
is designed to control the release of radioactivity in the liquid effluent streams so that radiations
dose to members of the public is with in those stipulated by the regulatory board. This system

30. 24
handles radioactive wastes that are carried in liquid streams from the laundry active floor
drains, decontamination center and chemical laboratories.
2.7.3 GAS RADIOACTIVE WASTE MANAGEMENT SYSTEM:
An extensive ventilation system collects potentially active exhaust air from such areas as the
Reactor Building, the storage area, the decontamination center and the heavy water
management area. The active and potentially active exhaust air and gases are all routed to a
gaseous effluent exhaust duct. This exhaust flow is monitored for noble gases, tritium, iodine
and active particulate before being released. Facilities for filtration are provided. Signals from
the iodine, wide range beta-gamma and particulate monitors are recorded in the control center.
Tritium monitoring is carried out by laboratory analysis.
2.8 SAFETY CLASSIFICATION OF SYSTEMS:
In the design of Indian PHWRs, it is required to grade various systems, equipment & structures
in their importance to safety & reliability. The safety gradation consists of four different safety
classes depending upon the nature of safety functions to be performed by the various items of
the plant.
2.8.1 SAFETY CLASS I:
It is the highest safety class & includes equipment & structures needed to accomplish safety
functions necessary to prevent release of substantial core fission product inventory. This
includes reactor shutdown systems & primary heat transport system.
2.8.2 SAFETY CLASS II:
Includes equipment, which performs those safety functions, which become necessary to
mitigate the consequences of an accident involving release of substantial core fission product
inventory from fuel. This class also includes those items, which are required to prevent
escalation of anticipated operational occurrences to accident conditions. Boiler feed water &
steam system, emergency core cooling system, reactivity control provisions & reactor
containment building are included in this class.
2.8.3 SAFETY CLASS III:
Includes systems that perform functions, which are needed to support the safety functions of
safety class II & I. Also, it includes systems & functions required to control the release of
radioactivity from sources located outside the reactor building. Process water-cooling system
include induced draft cooling towers, air supply system, shield cooling system primary coolant
purification ion exchange columns & filters etc. are included in this category.
2.8.4 SAFETY CLASS IV:
Includes those items & systems, which do not fall within the above classes but are required to
limit the discharge of radioactive material & airborne radioactivity below the prescribed limits
.D2O upgrading, waste management, dueteration & service building ventilation systems are
classified as class IV safety systems.
2.9 SAFETY
2.9.1 INDUSTRIAL SAFETY-We mean that the measures adopted as a whole in
industry to reduce accidents to bare minimum.
Factors responsible for Safety:
 Plant layout

31. 25
 Design of machinery
 Safety Gadgets and equpiments
 Protective aids
 Safety culture & Respect for Safety
 Attitude of the management/ employer - Caution Boards
 Display of Good practices about Safety
 Safety meetings, Open discussion and other measures
 Safety Manual
 Enforcement
 Unsafe Act & Unsafe conditions
2.9.2 CAUSES OF ACCIDENTS:
Hazards are the risks and perils or dangers that contribute to accidents and injuries.
"HAZARDS DO NOT CAUSE ACCIDENTS, PEOPLE DO"
2.9.3 KINDS OFHAZARDS:
 Fire
 Heat
 Material Handling
 Floors
 Ladders
 Tools
 Machinery
 Walking and Working surfaces
 Process
 Chemicals
 Electricity
 Unsafe Act
 Unsafe Condition
2.9.4 RADIATION SAFETY
Radiation in Nuclear reactor is produced in following ways :
 Directly in fission reaction

32. 26
 By decay of fission products
Following types of radiations are encountered:
 Alpha radiation
 Beta radiation
 Gamma radiation
 Neutron radiation
Out of the above types of radiations Alpha radiation is practically zero, whereas Beta and
Gamma radiation fields may be present almost everywhere inside the reactor building and
in negligible amount even outside the reactor building. Neutron radiations are mainly present
inside the reactor vault. It is worth noting that the secondary side of the plant i.e. feed water
and steam cycle etc. are completely separate from the nuclear systems and are therefore not
supposed to be and neither they are to carry any sort of radioactive particle and therefore
free of contamination and radiation. It is also worth noting that all radiations are emitted from
the nucleus of every radioactive nuclide which will always have a tendency to become stable
by emitting radiations through disintegration.
The following reaction shows the emissions of Alpha, Beta, Gamma and Neutron.
92U2382He492U234 + (alpha)
It has very low penetrating power and can be stopped by simple paper.
1H32He3 (18 KeV) +beta
It also does not have good penetrating power and in human skin it can penetrate up to about
half mm. It can be very easily shielded
92U235 + 0n1 92U236Xe + Kr + 0n1 + gamma + Heat
Following methodologies are used to control the exposure to the radiation and therefore
resistive of the radiation dose.
(1) Administrative Control
(2) Zoning Technique
(3) Design Control

33. 27
(4) Operation Control
(5) Maintenance and House keeping
Exposure to any kind of radiation can be controlled by an individual by following methods:
(1) Distance
(2) Shielding
(3) Decay (Time to Decay)
2.10 RAPPCOF (COBALT FACILITY)
Here, recovery of COABALT-60 SLUGS/PELLETS from the IRRADIATED ABSORBER
RODS received from different Nuclear Power Plants.
27Co59 +0n1 27Co60 +γ
Thermal 0n1 activation X-section: 37 Barns
 Sp. Activity of Carrier free Co60 : 1128 Ci/g
 Half Life: 5.27 year
 Radiations:
 β :0.31 MeV max.
 :γ : 1.17 MeV 100%
 :γ : 1.33 MeV 100%
Thermal Energy/1000 Ci : 4 cal/s
Radiation field at 1 mtr from 1 Ci : 1.35 R/hr
 SLUGS/PELLETS:
The facility is designed to handle about 1 Mega Curies of Co-60. In order to meet the demand
of high and medium specific activity Co-60 and also for the fabrication of sources of various
sizes and shapes, cobalt is irradiated in the form of nickel coated pellets of 1 mm dia x1 mm ht
for production of high specific activity Co-60 (> 100 Ci/g) and in the form of aluminum clad
slugs 6 mm diax 25 mm ht for the production of specific activity between 30-100 Ci/g.
Recovery of Co-60 from Cobalt Adjusters:
The cobalt adjusters are brought to RAPPCOF from power stations in a special shielding
flask. For complete recovery of cobalt activity, the following operations are carried out in a
sequence:
1. Discharging of adjuster into pool
2. Dismantling of adjuster in pool

34. 28
3. Transportation of sub-assemblies from pool to Recovery Cell
4. Cell door operation
5. Recovery of slugs/pellet capsules from sub-assemblies
6. Recovery of pellets
7. Preparation of transport pencils for slugs
8. Preparation of pellet capsules for transportation
9. Measurement of activity
10. Loading of cobalt in transport flask
11. Transportation of cobalt shielding flask
2.11 FIRE SECTION
Fire protection system in a nuclear power plant is meant To prevent damage to various
equipment or system due to fire.To ensure decay heat removal of the reactor. To minimize the
release of radioactivity to environment in the event of a fire.To provide backup PW cooling to
various systems. To ensure personnel spray supply.
Fire protection system consists of fire fighting water system, carbon dioxide fire protection
system and portable fire protection system.RAPS have one common fire section from unit 1-
6. It is located at 3&4 unit area .For fire production mainly three things are required
1) Fuel for burning
2) Oxygen to support fire and
3) The third one is temperature.
For fire extinguishing we remove any one out of these three things.
Fig 2.11 FIRE TRIANGLE
2.11.1 CLASSIFICATION OF FIRE
TABLE 2.11 CLASSES OF FIRE

35. 29
2.11.2 FIRE DETECTORS
a.) Smoke detectors
b.) Temperature detectors
2.12 ENVIRONMENTALSURVEY LABORATORY
OBJECTIVES OF E.S.L LAB AT RAWATBHATA
• Measurements of concentration of radio nuclides in various environmental matrices
collected Measurement of internal contamination due to gamma emitting radio
nuclides by whole body counting of RAPS radiation workers.
• Measurement of direct radiation exposure using environmental thermo luminescent
dosimeters.
• Computation of radiation does to the public and demonstrate compliance with
applicable regulatory limits from the environment of rawatbhata nuclear site.
ATMOSPHERIC TERRESTRIAL AQUATIC
Air tritium Soil Water
Rain water Grass Silt
Sulphide Cereals Grass
Air particulate Pulses Fish
Animal Milk Weed
TABLE 2.12 ESL LAB SURVEY
2.13 SUBSTATION
S.NO. CLASS OF
FIRE
SOURCE OF FIRE BEST EXTINGUISER
1. A wood, paper, ordinary combustibles Soda, acid, water
2. B Oil,paints,grease, gasoline, diesel,petrol Foam, co2
3. C Fire in gaseous substances(H2) Co2 gas
4. D Fire in chemicals, metals Co2, dry chemical
5. E Electrical fire Co2, dry chemical

36. 30
2.13.1 SIGNIFICANCEOF SUBSTATION
An electrical substation is an assemblage of electrical components including bus-bars,
switchgear, power transformers, auxiliaries etc. These components are connected in a definite
sequence such that a circuit. can be switched off during normal operation by manual command
and also automatically during abnormal conditions such as short- circuit.
Basically, an electrical substation consists of number of incoming circuits. and outgoing
circuit. connected to a common Bus-bar system. A substation receives electrical power from
generating station via incoming transmission lines and delivers elect. power via the outgoing
transmission lines.“Substation is integral part of a power system and form important links
between the generating station, transmission systems, distribution systems and the load
points.”
2.13.2 MAIN TASKS OF MAJOR SUB-STATIONS IN THE T&D
Main tasks associated with major sub-stations in the transmission and distribution system
include following:
 Protection of transmission system.
 Controlling the Exchange of Energy.
 Ensure steady State & Transient stability.
 Load shedding and prevention of loss of synchronism. Maintaining the system
frequency within targeted limits.
 Voltage Control; reducing the reactive power flow by compensation of reactive
power, tap-changing.
 Securing the supply by proving adequate line capacity.
 Data transmission via power line carrier for the purpose of network monitoring;
control and protection.
 Fault analysis and pin-pointing the cause and subsequent improvement in that area of
field.
 Determining the energy transfer through transmission lines.
 Reliable supply by feeding the network at various points.
 Establishment of economic load distribution and several associated functions.
2.13.3 TYPES OF SUBSTATION
The substations can be classified in several ways including the following:
 CLASSIFICATION BASED ON VOLTAGE LEVELS
e.g: A.C. Substation: EHV, HV, MV, LV; HVDC Substation.

37. 31
 CLASSIFICATION BASED ON OUTDOOR OR INDOOR
 Outdoor substation is under open sky
 Indoor substation is inside a building
 CLASSIFICATION BASED ON CONFIGURATION
 CONVENTIONAL Air insulated outdoor substation or SF6Gas
Insulated Substation.
 COMPOSITE SUBSTATIONS having combination of the above two
 CLASSIFICATION BASED ON APPLICATION
 STEP UP SUBSTATION – Associated with generating station as the
generating voltage is low.
 PRIMARY GRID SUBSTATION – Created at suitable load center along
primary transmission lines.
 SECONDARY SUBSTATION – Along secondary transmission line.
 DISTRIBUTION SUBSTATION – Created where the transmission line voltage
is step down to supply voltage.
 BULK SUPPLY AND INDUSTRIAL SUBSTATION – Similar to distribution
sub-station but created separately for each consumer.
 MINING SUBSTATION – Needs special design consideration because of
extra precaution for safety needed in the operation of electric supply.
 MOBILE SUBSTATION – Temporary requirement.
2.14 SUBSTATIONPARTS AND EQUIPMENT
Each sub-station has the following parts and equipment:
2.14.1 OUTDOOR SWITCHYARD
 Incoming Lines
 Outgoing Lines
 Bus-bar
 Transformers
 Bus post insulator & string insulators
 Substation Equipment such as circuit-breakers, isolators, earthing switches, surge
arresters, CTs, VTs, neutral grounding equipment.
 Station Earthing system comprising ground mat, risers, auxiliary mat, earthing strips,
earthing spikes & earth electrodes.
 Overhead earth wire shielding against lightening strokes.
 Galvanized steel structures for towers, gantries, equipment supports.
 PLCC equipment including line trap, tuning unit, coupling capacitor, etc.
 Power cables
 Control cables for protection and control
 Roads, Railway track, cable trenches

38. 32
 Station illumination system
2.14.2 MAIN OFFICE BUILDING
 Administrative building
 Conference room etc.
2.14.3 SWITCHGEAR AND CONTROLPANELBUILDING
 Low voltage A.C. Switchgear
 Control Panels
 Protection Panels
2.14.4 BATTERYROOM AND D.C. DISTRIBUTION SYSTEM
 D.C. Battery system and charging equipment
 D.C. distribution system
2.14.5 MECHANICAL, ELECTRICALAND OTHER AUXILIARIES
 Fire fighting system
 Diesel Generator (D.G.) Set
 Oil purification system
2.15 SWITCHYARD
Fig 2.15 SWITCHYARD
Distribution substation is a substation from which electric supply is distributed to the
different users. In a substation there are numbers of incoming and outgoing circuits each
having its isolator, circuit breaker, transformers etc. connected to bus-bar system.
The following equipment are installed in substations:

39. 33
 Distribution Transformer
 Circuit breaker
 Lightning Arrester
 Air Brake (AB) switches / Isolator
 Insulator
 Bus-bar
 Capacitor Bank
 Earthing
 Fencing
 Distribution panel board
2.15.1 DISTRIBUTIONTRANSFORMER
The distribution transformer is a main and largest equipment of distribution substation.It is
basically a static electrical device which steps down the primary voltage of 33kV or 11 kV
to secondary distribution voltage of 415-440 volts between phases and 215 volts between
phase and neutral through delta-star windings by electromagnetic induction without change
in frequency.
2.15.2 CIRCUIT BREAKER
The circuit breaker is an equipment which automatically cut off power supply of the system
when any fault or short circuit occurs in the system. It detects and isolate faults within a fraction
of a second thereby minimizing the damage at the point where the fault has occurred.
The circuit breakers are specially designed to interrupt the very high fault currents, which may
be ten or more times the normal operating currents.There are many types of circuit breakers, e.g. Oil,
minimum oil, Air blast,Vacuum, SF6, etc. being used at distribution substations.This list is generally in order of
their development and increasing fault rupturing capacity, reliability and maintainability.

40. 34
In distribution substation, generally oil circuit breakers, vacuum and air circuit breakers are
used.
Figure 2.15.2 – 33 kV outdoorvacuum circuit breakers
2.15.3 LIGHTNING ARRESTER
A lightning arrester (alternative spelling lightning arrestor) (also called lightning diverter) is a
device used on electric power systems and telecommunication systems to protect
the insulation and conductors of the systemfrom the damaging effects of lightning.
The typical lightning arrester has a high-voltage terminal and a ground terminal. When a
lightning surge (or switching surge, which is very similar) travels along the power line to the
arrester, the current from the surge is diverted through the arrester, in most cases to earth.
In telegraphy and telephony, a lightning arrester is placed where wires enter a structure,
preventing damage to electronic instruments within and ensuring the safety of individuals
near them.
Fig 2.15.3 LIGHTNING SURGES

41. 35
Smaller versions of lightning arresters, also called surge protectors, are devices that are
connected between each electricalconductor in power and communications systems and the
Earth.
These prevent the flow of the normal power or signal currents to ground, but provide a path
over which high-voltage lightning current flows, bypassing the connected equipment. Their
purpose is to limit the rise in voltage when a communications or power line is struck by
lightning or is near to a lightning strike.
If protection fails or is absent, lighting that strikes the electrical system introduces thousands
of kilovolts that may damage the transmission lines, and can also cause severe damage to
transformers and other electrical or electronic devices. Lightning-produced extreme voltage
spikes in incoming power lines can damage electrical home appliances or even produce death.
2.15.4 AIR BREAKER (AB) SWITCH / ISOLATOR
The switch whose contacts open in the air and quenching of an arc achieves by compressed air,
such type of switch is called an air brake switch. The air acts as a dielectric medium for the air-
break switch. It is more effective and reliable as compared to another switch. The air brake
switch is operated manually when their handle is placed on a ground level.
The air break switches install in outdoor and mainly use for switching and isolation. The air
break switch is mostly installed in the distribution network as a switching point. It interrupts
the small excitation current of a transmission line or the capacitive charging current. The
maximum voltage for the switches is up to 35kV. The air-break switches are classified into two
types. They are Single-Pole Air-Break Switch and the Gang Operated Air-Break Switch.
Single pole air-break switch uses for the opening of only one conductor. And for the opening
of more than one conductor at a time gang operated air break switch is used. The switches
which opened together are called the gang switches. The air-break switches are installed in two
ways, i.e., either horizontally or vertically and it is placed on the pole top or in pad mounted
metal enclosure.
2.15.5 INSULATOR
Electrical Insulator must be used in electrical system to prevent unwanted flow of current to
the earth from its supporting points. Theinsulator plays a vital role in electrical system.
Electrical Insulator is a very high resistive path through which practically no current can flow.
In transmission and distribution system, the overhead conductors are generally supported by
supporting towers or poles. The towers and poles both are properly grounded. So there must
be insulator between tower or pole body and current carrying conductors to prevent the flow
of current from conductor to earth through the grounded supporting towers or poles.
 INSULATING MATERIAL
The main cause of failure of overhead line insulator, is flash over, occurs in between line and
earth during abnormal over voltage in the system. During this flash over, the huge heat
produced by arcing, causes puncher in insulator body. Viewing this phenomenon, the
materials used for electrical insulator, has to possess some specific properties.
 PROPERTIESOF INSULATING MATERIAL
The materials generally used for insulating purpose is called insulating material. For
successful utilization, this material should have some specific properties as listed below-
1. It must be mechanically strong enough to carry tension and weight of conductors.

42. 36
2. It must have very high dielectric strength to withstand the voltage stresses in High
Voltage system.
3. It must possesses high Insulation Resistance to prevent leakage current to the earth.
4. The insulating material must be free from unwanted impurities.
5. It should not be porous.
6. There must not be any entrance on the surface of electrical insulator so that the
moisture or gases can enter in it.
7. There physical as well as electrical properties must be less effected by changing
temperature.
2.15.6 BUS-BAR ARRANGEMENT
The bus-bar is a conductor used to connect two and more equipment located side-by-side
when the currents are very high. These are usually rectangular, sometimes tubular, bare
copper bars supported on insulators. The outdoor bus-bars are either of the rigid type or of
the strain type.
In the rigid type, pipes are used for making connections among the various equipment. The
strain type bus-bars are an overhead system of wires strung between two supporting
structures and supported strain type insulators. Since the bus-bars are rigid, the clearances
remain constant.
2.15.7 CAPACITORBANK
It is a series parallel combination of capacitors required to improve power factor of the
system. They act as reactive power generators, and provide the needed reactive power to
accomplish active power of circuit. This reduces the amount of reactive power, and thus total
power (kVA) or the demand.
A Capacitor Bank is a group of several capacitors of the same rating that are connected in
series or parallel with each other to store electrical energy . The resulting bank is then used
to counteract or correct a power factor lag or phase shift in an alternating current (AC) power
supply. They can also be used in a direct current (DC) power supply to increase the ripple
current capacity of the power supply or to increase the overall amount of stored energy.
WHAT DO A CAPACITOR BANK WORK?
Capacitor banks work on the same theory that a single capacitor does; they are designed to
store electrical energy, just at a greater capacity than a single device. An individual capacitor
consists of two conductors which are separated by a dielectric or insulating material. When
current is sent through the conductors, an electric field that is static in nature then develops in
the dielectric which acts as stored energy. The dielectric is designed to permit a predetermined
amount of leakage which will gradually dissipate the energy stored in the device which is one
of the larger differences between capacitors and batteries.

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FIG 2.15.7 CAPACITOR BANK
HOW IS CAPACITANCE MEASURED?
Capacitors arerated by the storingcharacteristicreferred to as capacitancewhich is measured by the scientific
unit,farad.Each capacitor will havea fixed valuethatthey arerated atstoringwhich can beused in combination
with other capacitors in a capacitor bank when there is a significant demand to absorb or correct AC power
faults or to output DC power.
WHAT ARE THE APPLICATIONS OF A CAPACITOR BANK?
The most common use of a capacitor bank for AC power supply error correction is in industrial environments
which usea largenumber of transformers and electric motors.Sincethis equipment uses an inductiveload,they
are susceptible to phase shifts and power factor lags in the power supply which can result in a loss of system
efficiency if left uncorrected. By incorporatinga capacitor bank in thesystem, the power lagcan be corrected at
the cheapest cost for the company when compared to making significant changes to the company power grid
or system that is supplying the equipment. Other uses for capacitor banks include Marx generators, pulsed
lasers, radars, fusion research, nuclear weapons detonators, and electromagnetic railguns and coil guns.
2.15.8 EARTHING
Provision of an effective, durable and a dependable earthing in a substation and switching
stations is very important for the safety of operating personnel as well as electrical devices.
The voltage levels do not rise above tolerable thresholds and that the earth connection is
rugged to dissipate the fault to the earth.
Earthing has a very low resistance and connects the electrical equipment to the general
mass of the earth.
Definition: The process of transferring the immediate discharge of the electrical energy
directly to the earth by the help of the low resistance wire is known as the electrical earthing.

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The electrical earthing is done by connecting the non-current carrying part of the equipment
or neutral of supply system to the ground.
Mostly, the galvanized iron is used for the earthing. The earthing provides the simple path to
the leakage current. The short-circuit current of the equipment passes to the earth which has
zero potential. Thus, protects the system and equipment from damage
2.15.9 FENCINGARRANGEMENT
Fencing is provided at outdoor substation yard for restricting entry of unauthorized person and
livestock. It must be earthed/ grounded separately. Height of fencing normally should not be
less than 1.8 meters. Fencing should be painted once in a year by suitable paint.
2.15.10 DISTRIBUTIONPANELBOARD
Distribution panelboard consists of MCCBs, control equipment, meters and relays are housed
in the control room. The panel frame shall be connected to the earth grid by an earthing
conductor. A rubber mat of prescribed size and quality shall lay in front of panel.
2.16 CHALLENGES AND OPPORTUNITIES FOR FUTURE
Current world challenges such as energy demand, climate change and energy security are
opportunities for the nuclear industry. According to researches the energy consumption will
grow about 50% by 2030 with electricity use doubling globally and tripling in developing
countries. Another concern is energy security which is already a primary challenge for many
countries.
All these world challenges have tended to increase the opportunities for the nuclear power and
strengthen the achievements in Nuclear Power development, including its safe operation.
For the global nuclear power to be sustainable and to contribute to the world’s energy supply
mix in the long term, it must respond to the challenges of further development. Among these
challenges are the availability of uranium resources, management of waste, safety, public
acceptance, aging of the facilities and workforce, complex infrastructure, and non-
proliferation.
2.17 FUTURE OF INDUSTRY
The nuclear power programme in India up to year 2020 is based on installation of a series of
MWe& 500MWe pressurized heavy water reactor (PHWR) UNITS. 1000MWe light water
reactors (LWR) coming two 5 year plans. The total installed capacity of nuclear generation
would increase UNITS & fast breeder reactors (FBR) units. NPCIL plans to contribute about
10% of the total additional needs of power of about 10000MWe per year i.e. 1000 MWe per
year.

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CHAPTER-3
CONCLUSIONS
Utilizing Nuclear Energy is needed if humanity is to continue its advancement. It has great
potential to be quiet a useful and beneficial part of humanity’s growth and development in the
decades to come. The problem is when we lose our respect, caution and give in to our naivety
and arrogance, a devastating disaster awaits us, and it is callous in the destruction it causes.
The practical training at Rajasthan Atomic Power Station has proved to be quite faithful. It proved
an opportunity for encounter with such huge components like 220MW generators, turbines, etc. the
architecture of the NPP (Nuclear Power Plant).
The wayvarious units arelinked and the wayworking of whole plant is controlled make the students
realize that engineering is not just learning the structure description and working of various
machines, but the greater part is of planning, proper management.
It also provides an opportunity to learn technology used at proper place and time can save a lot of
labour for example almost all the controls are computerized because in running condition no any
person can enter in the reactor building.
But there are few factors that require special mention. Training is not carried out into its tree spirit.
It is recommended that there should be some projects specially meant for students where the
presence of authorities should be ensured. There should be strict monitoring of the performance of
students and system of grading be improved on the basis of the work done.
However training has proved to be quite faithful. It has allowed as an opportunity to get an exposure
of the practical implementation to theoretical fundamental.
An engineer needs to have not just theoretical knowledge but practical knowledge also. So
every student is supposed to undergo a practical training session after 3rd year. I have taken my
summer training NUCLEAR TRAINING CENTRE (RAPP) where I practically saw that how
electric power is generated. I have also got a chance to saw different electrical equipments
which helps me to enlarge my knowledge.
During our 45 days training session we were acquainted with the working of the power plant.
At last I would like to say that practical training taken at NTC (RAPP) has broadened my
knowledge and has widened my thinking as a professional.

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3.2 REFERENCES
[1] www.npcil.nic.in
[2] en.wikipedia.org/wiki/nuclear_power_corporation_of_india.
[3] india.areva.com/…/areva-s-nuclear-epr-projects-in-india-areva-india.html.
[4] Book on “Safety classification of structures, system and components in nuclear power
plants”.
[5] Jain, S.K., Nuclear Power – An alternative (pdf), NPCIL, retrieved 4 March 2012

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