Narora Atomic Power Station (NAPS) Vocational Training Report for ECE
This is the summer training report of NAPS,Narora.
report consist all the electronics system that i coverd in NAPS.
yes ALL of them. :)
Published on: Mar 3, 2016
Transcripts - Narora Atomic Power Station (NAPS) Vocational Training Report for ECE
NUCLEAR POWER CORPORATION OF INDIA
(A GOVT. OF INDIA ENTERPRISE)
Guided By: Prepared By:
Mr. Gaurav Sharma (Trg. Supt) KUSHAL VARSHNEY
Mr. Khagesh Chandra Rakesh (Trg. Officer) B.Tech (ECE, 4th Year)
Mr. H.C Gaur, SO/F Inderprastha Engineering College,
Mr. G.S.Rawat, SO/C Ghaziabad.
This is to certify that Mr.___________________________ has partially completed
/ not completed the Training in our Organization / Industry during the period 15-06-
2015 to 14-07-2015. His overall performance during the period was Excellent /
Very Good / Good / Average / Poor.
Signature & Sealof Training Manager
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 provides a six weeks
industrial training 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 NARORA
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 30 days at the plant.
It was highly educative & interactive to take training at
NARORA ATOMIC POWER STATION. As technical
knowledge is incomplete without practical knowledge, I couldn’t
find any place better than this to update myself.
I am very much thankful to the Station director Shri. D. S.
Choudhary & Training superintendent Shri. G. Sharma for
allowing me for the industrial training at NAPS. Thanks to Shri.
Khagesh Chandra for their valuable guidance during my project.
I also take the opportunity to thanks Nuclear training Centre for
providing lecture on overview of the plant and providing me
1.0 Introduction to NAPS
1.1 NAPS Plant layout
1.2 Some important data of NAPS
1.3 Nuclear Power stations in India
1.4 Principle of Nuclear Reactor
1.5 Nuclear Reaction
1.6 Heavy water and its usage
1.7 Moderator System
1.8 Primary heat transport system
1.9 Reactor fuel
1.10 Shut down system
1.11 Steam cycle
1.12 Main Control Room
2.0 Important measurement at NAPS
2.1 Pressure measurement
2.2 Temperature measurement
2.3 Level measurement
2.4 Flow measurement
3.0 Control Maintainance Section
4.0 Control Room Computer System
4.1 System descriptions
4.2 Communication system
5.0 Public Address System
INTRODUCTION TO NAPS
One of the chief aims of the Department Of Atomic Energy is the development
of Nuclear Energy for economic generation as an alternative source of electric
power when in due course the conventional sources will be exhausted in the
country. Petroleum prices are escalating. The amount of coal required for
400MWe power generations of the order of 5 x 106 KGs per day. Whereas a
Nuclear Power Station of the same capacity needs only 200 kg of Atomic Fuel
per day. Transportation of coal of such magnitude over long distance is not
NARORA, a small ancient village, is situated on the bank of Holy River Ganga
in the district Bulandshahr in Uttar Pradesh. The plant is about 60 km from
Aligarh, which is the nearest population center. With the synchronization of the
Narora Atomic Power Station with northern grid through five lines of 220KV, it
has occupied an important place on the power map of the India. With this, yet
another important milestone in the Indian nuclear program has been achieved,
as NAPS is an effort towards standardization of PHWR Units & a stepping-
stone to the 500MWe units. A significant & unique feature of this project has
been the evolution of the design suitable for seismic sites.
The NAPS is a twin unit module of 220MWe. Each of pressurized heavy water
reactors. The reactors use natural uranium available in India as fuel & heavy
water produced in the country as moderator & coolant. A NAPP is the fourth
Nuclear Power Station in the country after Tarapur in Maharasthra, Rawatbhata
in Rajasthan & Kalpakkam in TamilNadu. NAPS is the first indigenous Nuclear
Power Plant of India. The station has two pressurized heavy water reactors with
installed capacity of 220MWe, each using natural uranium as fuel. The station is
connected to high voltage network through five 220 KV lines, one to
Moradabad, one to Atrauli, one to Simboli, & two to khurja. It is designed for
base load operation as a commercial station.
TOP VIEW OF NARORA ATOMIC POWER PLANT
Reactor Building houses the Reactor Primary Heat Transport System,
Moderator System, Reactivity System, Fuel Handling System & some of the
Auxiliaries. The Turbo-Generator & its associated conventional equipment,
Emergency Diesel Sets, Control & Power MG Sets, Station Batteries, Electrical
Switch Gear Compressors, Chillers & Main Control Room are located in
Turbine Building. Both the units share common facilities such as Service
Building, Spent Fuel Storage Bay (SFSB) & other auxiliary devices such as
Heavy Water Upgrading & Waste Management Facility. NAPS have two
natural draught cooling & two induced draught cooling towers. NAPS have the
following main parts: -
5. Switchyard 9. Reactor Building
2. Domestic Water
6. Stack 10. Purification Building
3. Canteen 7. Service Building 11. Turbine Building
4. NDCT 8. Supplementary 12. Pump House
SOME IMPORTANTDATA OF NAPS
Transmission Lines Five
220 KV Narora – Moradabad Single Line
222200 KKVV NNaarroorraa ––HHaarrdduuaaggaannjj Single Line
220 KV Narora–Simbholi Single Line
220 KV Narora–Khurja Double Line
Stack Height 142 Meters
NDCT Height 128 Meters
NDCT Top Diameter 58 Meters
NDCT Base Diameter 107 Meters
Steam Pressure 40-48 Kg/cm2
PHT Pressure 87.0 Kg/cm2
Coolant Tubes 306
No.of Fuel Bundles in one channel 12
Fuel Bundle Weight 15Kgs
No. of Bundles in a core 3672
Condenser Vacuum 680 MM of Hg
RB Design Pressure 1.25 Kg/cm2
Station Load 18 - 20MWe
Generator Power 220MWe
Grid Voltage 220 KV
ISO-14001 certification 19th AUGUST 1999
STATIONS IN INDIA
Capacity Of The Running India’s Atomic Power Stations Given
S.NO. Name of unit & Place CAPACITY Total
1. TAPS-1&2,Tarapur 2X160Mwe 320Mwe
2. TAPP-3&4,Tarapur 2X540Mwe 1080Mwe
3. RAPS-2,Rawatbhata 1X200Mwe 200Mwe
4. RAPS-3&4Rawatbhata 2X220Mwe 440Mwe
5. RAPS-5&6Rawatbhata 2X220Mwe 440Mwe
6. MAPS-1&2,Kalpakkam 2X220Mwe 440Mwe
7. NAPS-1&2,Narora 2X220Mwe 440Mwe
8. KAPS-1&2,Kakrapara 2X220Mwe 440Mwe
9. KGS-1&2,Kaiga 2X220Mwe 440Mwe
10. KGS-3&4,Kaiga 2X220Mwe 440Mwe
PRINCIPLE OF NUCLEAR REACTOR
A Nuclear Power reactor is only a source of heat, the heat being produced
when the uranium atom splits (fission). The heat produces steam, which drives
the turbo-generator & produces electricity. Natural uranium, the fuel used in
this reactor, consist of two types (isotopes) of uranium namely U-235 and U-
238 in the ratio of 1:139. It is the less abundant i.e. U-235 isotope that fissions
and produces energy. When a U-235 atom is struck by a slow (or thermal)
neutron, it splits into two or more fragments. Splitting is accompanied by
tremendous release of energy in the form of heat, radioactivity & two or three
fast neutrons. These fast neutrons, which fly out of the split atom at high
speeds, are made to slow down with the help of moderator (heavy water). So
that they have high probability to hit other 92U235atoms which in turn releases
more energy & further sets of neutrons and fission. Attainment of self-
sustained fission of uranium atoms is called a ‘Chain Reaction’. At this stage
the reactor is said to have attained “criticality”.
Heavy Water is used in the Reactors as moderator & reflector for the neutrons
and as coolant for the Reactor fuel. The two functions are separate, each having
its own closed circulating system. The fuel coolant system is called the Primary
Heat Transport System, and is a high pressure, high temperature circuit. The
moderator and reflector circuit is called the moderator system, and is a low
pressure, low temperature circuit. The Pressure tubes &Calandria Tubes are
insulated from each other in the Reactor core by Carbon di-oxide Gas in the
annular space between the calandria tubes and the coolant tubes. Figure shown
below is a simplified schematic diagram of the Reactor Cycle. Heavy water at
293 0C enters the Steam Generator tubes to raise steam from Demineralized
Water in shell side, for the turbine and returns back to the Reactor at 249 0C.
The working pressure, which is the mean of the pressure, in the Reactor inlet &
outlet headers is 87.0 Kg/cm2.
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Moderator (D2O) system circulating pump take suction from bottom of
calandria& discharge back to calandria through moderator heat exchangers for
maintaining moderator temperature. Moderator inlet to calandria is at its middle
point from two opposite sides. Working pressure and temperature of moderator
system are 8 Kg/cm2 and 650C respectively with a cover gas pressure of 0.25
In order to avoid escape & loss of Heavy Water from PHT / Moderator System,
a high standard of integrity is maintained by using multiple seals & leakage
collection system in the liquid phase. D2O Vapour recovery Dryer Systems is
used for the vapour phase collection.
TURBINE AND STEAM CYCLE:
At rated power, 1.33 x 106 Kg/hour of saturated steam at 39.7 Kgf/cm2 pressure
is provided by Four Steam Generator to supply to the Turbine. The Turbine
rated at 220 Mew, is a tandem compound machine with one high-pressure
cylinder and one low-pressure cylinder with double flow. From the outlet of the
HP cylinder, the steam at a pressure of 5.6 Kg/Cm2 passes to a pair of moisture
separator and then to a pair of reheater, where steam is heated up to 233oC for
admission to the low-pressure cylinder. Steam exhausted from the L.P. turbine
is condensed in a single pass condenser capable of maintaining a vacuum of 680
mm of Hg with a NDCT cooled water temperature of 320
C. The feed water is
heated in six stagesup to 1710
C and sent to the Steam Generators. The Steam
Re-heater drain is returned separately to Steam Generators.
The basic atomic energy we get from the process called nuclear fission of the
92U235 atom with the thermal neutron. The typical fission reaction is as
+ 2 0n1
+ y (Heat Energy) +
+ 3 0n1
+y (Heat Energy) +Y
The fission process releases energy. The transformation of this
energy is as shown below: -
Nuclear Fission Energy
(Formation of steam)
(Operating Turbine & Generator)
(With the help of generator)
HEAVY WATER AND ITS USAGE
Heavy water is used as both the moderator and coolant. Heat energy is
transported by coolant from reactor to the vertical, integral U-tubes in shell type
of heat exchangers, which functions as a boiler to produce steam and drives
Turbo Generator. The heavy water (D2O) is identical to the ordinary water
(H2O) as far as the chemical properties are concerned. However, in physical
properties there are minor variations (boiling point 101.4oC and freezing point
3.82oC). The deuterium (D2) in heavy water is an isotope of hydrogen (H2)
having one neutron and one proton in its nucleus. The absorption cross-section
of heavy water for neutron is far less than the ordinary water, which helps in
The moderator system is a heavy water and helium system. Calandria is always
full of moderator up to 96% and remaining volume is covered by helium gas,
which acts as cover gas. Moderator is used to slow down the speed of fast
neutron. Moderator (D2O) system circulating pump take suction from bottom of
calandria and discharge back to calandria through moderator heat exchanger for
maintaining moderator temperature. Working pressure and temperature of
moderator system are 8Kg/cm2 and 63oC respectively.
PRIMARY HEAT TRANSPORT SYSTEM
The fuel coolant system is called the primary heat transport system and is a high
pressure and high tempckt. The coolant transports this heat to the four steam
generators. Four pumps maintain the circulation through pressure tubes around
the fuel bundles, each having a capacity of 3560m3/hr. The coolant temperature
at inlet & outlet of a reactor are 249oC & 293.4oC respectively at a pressure of
101 kg/cm2& 87 Kg/cm2 respectively. A pressuring pump maintains the system
pressure using automatic feed & bleed principle instrument relief valves &
suitableregulating & protective system action limit the system pressure to 93.91
Kg/cm2. PHT is constantly pressurized at 87Kg/cm2 to keep it in liquid form at
295oC. High pressure, high temperature heavy water areas have been separated
from high pressure, high temperature light water areas for recovery of high
isotopic purity heavy water.
Fuel from the reactor is in the form of bundles 49.53 cm long & 8.17cm dia&
each bundle consists of 19 hermetically seal zircaloy tubes containing compact
& sintered pallets of natural uranium. Twelve such bundles are located in each
NAPS are provided with two diverse & independent shut down system, one fast
acting & other slow acting. The primary shutdown system has shutoff
mechanism at 14 locations in the reactor. Each of the 14 mechanisms has
cadmium sandwiched steel as neutron absorbing element. Normally these rods
are parked outside core during power operation & fully in on a trip signal. The
rods are held out of reactor core by rope & drum arrangement. These rods drop
in the core under gravity whenever a trip signal is received, & make the reactor
sub-critical in less than 2.3 sec.
The secondary shutdown system is a fast acting back up system to the primary
shutdown system. This system provides sufficient reactivity worth by promptly
filling twelve vertical tubes in the reactor core with a neutron absorbing liquid
(Lithium Pentaboratedeca –hydrate). The principle is such that four when liquid
filled tanks are pressurized than the liquid rises up in liquid tubes located inside
reactor. It makes the reactor sub-critical in 1.4 sec.
Both the shut down systems are backed by Automatic Liquid Poison addition
system injecting controlled quantities of boron into the moderator after
receiving the appropriate signal to ensure guaranteed sub-criticality of the
reactor for prolonged periods. Whenever there is total blackout of the station &
automatic liquid poison system is not available, addition of poison, under
gravity, to moderator is incorporated.
The turbine is an impulse reaction type, designed for saturated steam duty,
revolving at 3000 rpm with steam condition of 39.71 kg/cm2 pressure & 0.26%
wet & 250.3oC at inlet to stop valves. The turbine each rated at 235 Mew is a
tandem compound machine with one high-pressure cylinder and one low-
pressure cylinder with double flow. From the outlet of the high pressure
cylinder the steam passes to a pair of moisture separator and then to a pair of
reheater where steam is heated up to 233oC and 5.6/cm2 for admission to the
low-pressure cylinder. Steam exhausted from the L.P turbine is condensed in a
single pass condenser. Steam is extracted from suitable stages of the turbine to
provide for 6 stage regenerative feed heating, with a final feed water
temperature of 171oC.
Deareator L.P Turbine
MAIN CONTROL ROOM:
Control Room as the name suggests, what it is? It is a place from where every
instrument device etccan be controlled in either field or Reactor Building.
Control Room is the most important place in any nuclear power plant. It is a
place, which has full control over the reactor and all its peripheral. It has
separate system wise, panels for both units. On any error in any device or
system an audiovisual indication is produced in the control room. It also has
fuel-handling panel from where staff members can see the calandria channel by
CCTV cameras and refueling is done from this panel only.
To present the operator with the desired information in a compact, overall
fashion and reduce the large number of recorders, meters and annunciating
windows used in the earlier plants, a computer based operator information
system is introduced in NAPS called as control room computer system (CRCS).
This system is designed as purely informative system, with no control features
being included in the system. The information is presented in any desired
format and alarm annunciations are provided by color CRT displays. The
standardization input signal is used in CRCS. The input signal is represented as
0.5-4.5V. At zero signal reading is 0.5Vand at full signal reading is 4.5V.The
representation of row signal from sensors is represented into the standard form
by Signal Conditioning Modules (SCM). There are separate SCM for different
type of signal. These SCM are separate for both units and are located in the
Control Room Computer system itself. Moreover all the paperless recorders
installed at NAPS are connected to a common computer through LAN, where
all the data is stored and constantly monitored.
MONITORING SYSTEM (CTM):
Channel Temperature Monitoring System measures
1. The temperatures of the coolant (PHT) at the outlet of all the 306
2. The differential temperatures of sixteen selected channels.
This system mainly
Detects low coolant flow and apply corrective action for reactor
Provides a signal for flux tilt control
Helps in efficient fuel management by monitoring channel
outlet temperature and other related temperature.
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ccrroossss sseeccttiioonnaall aarreeaa ::
r . L
R = ---------
Where R = Resistance (ohms), r = Resistivity (ohms), L = Length , A = Cross
RTD Materials: The criterion for selecting a material to make an RTD is:
the material must be malleable so that it can be formed into small
it must have a repeatable and stable slope or curve.
the material should also be resistant to corrosion.
the material should be low cost
it is preferred that the material have a linear resistance verses
One of the common RTD materials is Platinum with a temperature coefficient
of 0.00385 - 0.003923 Ω/Ω/°C and practical temperature range of -452 to
+1100°F (-269 to +593°C). The platinum RTD has the best accuracy and
stability among the common RTD materials. The resistance versus temperature
curve is fairly linearand the temperature range is the widest of the common
RTD materials. Platinum has a very high resistivity, which means that only a
small quantity of platinum is required to fabricate a sensor and making
platinum cost competitive with other
RTD materials. Platinum is the only RTD commonly available with a thin film
element style. Platinum is the primary choice for most industrial, commercial,
laboratory and other critical RTD temperature measurements. Copper, nickel
and nickel iron are also commonly used RTD materials which are usually used
in low-cost non-critical applications.
Reference grade platinum is made from 99.999% pure platinum. It will produce
a maximum temperature coefficient of 0.003926Ω/Ω/°C. The maximum
temperature coefficient can only be achieved in Standard Platinum Resistance
Thermometers (SPRT) for laboratory use.
Types of RTD:
Wire wound type Coiled element type
Thin film element 2-wire RTD
Similarly, there are 3 and 4-wire RTD as well. The RTD used in
nuclear applications is the wire wound strap-on type.
CTM Basic Circuit:-
Current flow at 300 deg. Celsius~17 mA
Current flow at 30 deg. Celsius~19 mA
The TA card consists of a comparator and a relay. The RTD strapped on
channel outlet measures the temperature of channel which results as voltage
across it. This voltage can be determined by applying voltage divider rule across
the potentiometer (VRTD). This voltage is applied to +ve terminal of the
comparator. On the –ve terminal, RTD voltage corresponding to 299 degree
Celsius is applied. When VRTD is less than V299, the comparator o/p is –ve and
hence the relay is energized. If temp. exceeds 299 degree Celsius, the
comparator o/p becomes +ve and the relay de-energizes. Hence, the increase in
temp. can be monitored.
A modified circuit involves use of 15V instead of 36V reference voltage.
As the reference voltage decreases, the voltage across RTD for the same
temp.also decreases. This in turn decreases the self-heating error. Accuracy
increases but sensitivity, i.e., per degree voltage change decreases.
Zone Temperature Monitoring
The entire CTM matrix of 306 coolant channels are grouped into 8 Zones and
they are named as A1, B1, C1, D1, A2, B2, C2 and D2.Zones A1, B1, C1 and
D1 each consists of 31 channels. Zones A2 and C2 each consists of 48 channels
whereas, zones B2 and D2 each consists of 43 channels. Signals from the wiper
of 10-ohm potentiometer are connected to comparator cards as input signals. A
voltage signal corresponding to 299 deg C is fed as the reference signal alarm.
The two installations “TA” alarm contacts are wired with 2/2 coincidence
circuit for reactor setback. The comparator circuit also provides the voltage
signal to light LED during alarm condition. The LEDs for all channels are
arranged in matrix form in each panel. On the comparator PCB, 40K ohm
resistance is mounted whose one end is connected to input signal and the other
end is brought out on the PCB connector. These resistors of the zones are
averaged to get the summing signal for ZMT. The reference signal
corresponding to 299 deg C (required for channel outlet temperature very high
comparison) and 250 deg C (required for zone mean temperature indication
above 250 deg C) are derived from 36V power supply itself. The reference
signal corresponding to 299 deg C and 250 deg C are fed to buffer amplifiers
and the output of buffer amplifiers are connected to comparator cards and ZMT
indicating alarm meters respectively.
Zone mean temperature is defined as the arithmetic mean of the temperature of
all the channels of a particular zone. Signals from wiper of 10 ohms
potentiometer are also fed to CTM computer through 220K ohms resistors,
which provide display/print out of a single or all channel temperature data and
It encompasses monitoring and control of various plant parameters principle of
redundancy, diversity testability and maintainability are given prime
consideration. A high degree of automation is aimed at to promote reliability.
The system is design to confirm to fail safe criteria. All visual indication to
control, which may require intervention during operation, is located in a single
central control room. The safety systems are generally triplicates, the safety
function being achieved by 2 out of 3 logic’s. Each channel is totally
independent of other channels with separate sensor, signal
handing equipment, cable routes and power supplies. In channel temperature
monitoring system, only two channels are used with coincident logic of 2 out of
2 to reduce the power. The instrumentation for the control and protection
system is kept separate and independent of each other. A computer based
operator information system is used for data information display for operators.
If any default occurs in the system it will inform the operator by audio-visual
window annunciates system, which is provided on control room panels to cover
certain essential parameters.
Pressure is one of the important variable encountered in the nuclear power plant,
because uncontrolled it can lead to severe damages and loss of efficiency.
Following are the some important examples of pressure measurement.
Primary heat transport is pressurized to prevent vapor flashing and thus power
Moderator pump suction pressure is controlled to ensure that the helium-
circulating tank will not flood under certain conditions.
Steam pressure is controlled to ensure economic efficiency and power control.
Pressure is actually the measurement of force acting on area of surface. The
units of measurement are either in pounds per square inch (PSI) in British units
or Pascal (Pa) in metric. One PSI is approximately equal to 7000 Pa.
Common pressure detectors are Diaphragm, strain gauge, and bourdon tubes,
differential pressure transmitters.
Scale of pressure measurement is
1) Gauge pressure
2) Absolute pressure
3) Vacuum scale, usually stated in inches of mercury below
P Gauges=P absolute – P atm
P vacuum=P atm – P absolute
The primary sensor used in the temperature measurement is
thermocouple (T/C), bimetallic strip and resistance temperature
Thermocouple : - A T/C consists of two pieces of dissimilar metals
with their ends joined together. When heat is applied to the junction, a
voltage, in the range of mille-volts (mV), is generated. A
thermocouple is said to be self-powered.
Resistance Temperature Detector: - The resistance of device
various as the temperature increases. RTD is one of the most accurate
temperature sensors. Not only does it provides good accuracy it also
provide excellent stability and repeatability.
The measurement of level in nuclear power plant assume sample significance
specially in heavy water system as can be seen from the below given example:
Moderator level is measured and control for reactivity adjustment.
Dump tank sump level is a measure to ensure a low level will not lead to
Storage tank level is a direct indication of heavy water contents; a drop in level
could be only because of leakage.
Boiler drum level is measured and controlled to provide adequate heat sink for
the reactor and to match the requirement of steam to turbine.
Ultrasonic method of level measurement: -The ultrasonic operates on the
principle of sonar. Sound waves are sent out to the free surface of liquid under
test and are reflected back to the receiving unit, level changes are accurately
measured by detecting the time intervals taken for the waves to travel to the
surface and back to the receiver. The longer the time interval, the farther away
is the liquid surface, which in turn is an indication of level measurement.
The ultrasonic gauge needs physical contact with the material. It is non-
disturbance technique. It can be use for solid and liquid material level
The flow measurement is very important in process industries because it
establishes definite ratios and quantities of process materials for production
quantity control. In nuclear plants, flow measurement is critical for cooling
loops such as calandria spray flows; adjuster rod coolant flow is measured in
selected channels only. In case of other cooling loop such as bleed cooler,
moderator heat exchanger, a low process water flow would result in high outlet
temperature. In moderator circulation system, a low flow could point towards
cavitations of pumps. In turbine generator steam, flow directly depends on the
load. Flow can be measured by venturi tube
Venturi Tube: -The flow of liquid through the venturi tube establishes the
pressure differential, which can than be measured and related to the flow rate. In
this tube, a large pressure recovery can be made, and flows can travel through it
with much higher velocity without the turbulence, which destroys the accuracy
of orifice plates.
Control Maintenance Section (CMS) is an Instruments maintenance Section that
carries out all the control system jobs related to electronics and process
instrumentation. Calibration Lab (ISO-17025 certified) also known, as NAPS
Instruments Testing Laboratory is an important part of CMS. This lab consists
of instruments and master instruments, which are calibrated periodically and can
be further used in the field. Role of calibration lab in control maintenance
i) To maintain standardization of all master instruments from standardization
Organizations i.e. ERTL (N), NPL
ii) To maintain healthiness of all master instruments.
iii) To calibrate all test equipments with master equipments.
CMS maintains healthiness of all electronics and process instruments of the
plant with the help of routine checks, preventive maintenance and attends
breakdown maintenance jobs as earliest without affecting power generation.
Actually, in NAPS, CMU lab is divided into three sections:
a) Electro-technical lab (temperature. = 25+ 2.5 deg C and Relative Humidity
=35 to 65%).
b) Temperature lab (Temperature. = 25+ 2.5 deg C and Relative humidity =35
c) Pressure lab (temp. = 23+ 1.0 deg C and reactive humidity 45 to 55%).
CONTROL ROOM COMPUTER
CRCS system is a comprehensive information storage/retrieval
system with varieties of features, which are exclusively designed according to
the needs of the nuclear power plant operator. It is meant for acquiring data
from host, processing and presenting to the operator with the information
required to check the healthiness of the plant and analyze its behavior during its
CRCS is a configured as a client server configuration built around an Ethernet
LAN. The servers are dual redundant working in Active as well as Hot Standby
mode. This LAN is called the Work Station LAN(WSLAN). The CRCS
provides most of the information, which was usually displayed on panel meters
in earlier plant. It is used for dynamic value, bar graph display. Graphical
display of plant parameters, Alarm reporting, trending, mimic display,
disturbance recording etc. This system is used for data co-ordination and
This system has the following points:
1200 Analog points for field parameters monitoring
1280 Digital input points for field contacts monitoring.
256 Event sequence record digital input points.
128 Digital output points for DNM processing, Tritium in air
i) Buffer Terminal Cabinet (BTC):-
All the field signals are terminated at the BTC panels. From BTC
another cable is connected to different (I/O) panels of CRCS.
ii) I/O panels:-
There are four I/O panels in CRCS. One I/O panels is having 300 analog
points, 320 digital input points, and 32 digital input points and 32 digital
output points. Analog field input is terminated at Signal Conditioning
Modules (SCM) through BTC.
iii) Signal Conditioning Module (SCM):-
All the analog signals are terminated at SCM. SCM provides isolation
and conditioning of the signal. The output of SCM is uniform i.e. 0.5Vdc
to 4.5Vdc signal.
The SCM converts the field signal in the range of 0.5V to 4.5Vdc. This
signal is connected to analog input (AI) card. 30 such inputs are
connected to one AI card and 10 such AI cards are there in one I/O. These
AI cards are used to mutiplexing and converting the signal from analog to
digital. 32 Ch. ADC & multiplexer are used in AI cards. Ch no. 16 and
Ch no. 32 are used as a reference low and reference high channels.
iv) Digital input card:-
The field input contacts are terminated at digital I/P cards through BTC. 32
such field inputs are connected to each digital card. 10 such digital input
cards are available in each I/O. Each I/O handles 320 nos. potential free
field contacts suitable for 24Vdc operation and voltage level inputs.
v) I/O Bus interface card:-
I/O bus interface card is used as a buffer card and transferring the data to
the I/O bus.
vi) I/O Bus to ISA Bus interface card:-
Once the data is transferred to the I/O bus it is required to be fed to the
industrial PC for computing the data. To communicate between I/O bus and ISA
bus interface card is used. Once the data is transferred to ISA bus now it is
available to industrial PC for processing.
vii) Industrial PC:-
It is Dual redundant industrial Pentium -II 233 MHz PC. Dual PCs are
available in single housing. The digital data is processed here and converted
into raw value. This raw value is transferred to server, through Local Area
Network (LAN) Soft ware of each PC checks the healthiness of the other
There are two servers in which one is active server & other is standby server.
These servers work in hot stand mode. Each server has the plant database. It
updates the data by communicating with every I/O node in the system, sends
output to the printers connected on request and sending data request query to the
I/O nodes and data to the display station periodically. It is a Pentium - III 500
ix) Display Station:-
This is a client of the server to display the data in different formats like bar
charts, trends curves, dynamic value of parameters etc. Display stations are
installed at panels of C/R. These are abbreviated as UCRT & ACRT. Total
numbers of UCRT’s and ACRT’s are as follows in each unit.
UCRT - Utility Cathode Rays Tube -10 Nos.
ACRT - Alarm Cathode Rays Tube -02 Nos.
UCRT - To display the bar chart trending, dynamic value and taking the
print out of the query generated by the user.
ACRT - To display the current alarms and printing on alarm printer with
x) POWER SUPPLY:-
There are following type of power supply used for one I/O system.
i) 24VDC - For SCM power supply & digital contact inputs.
ii) ±15VDC - For operational amplifiers
iii) +5VDC - For logic ckt
COMMUNICATION SYSTEM AT
VERY SMALL APERTURE TERMINAL (VSAT) SATELLITE
A very small aperture terminal (VSAT) is a two way satellite ground station
with a dish antenna that is smaller than 3meters, VSAT data rates typically
range from narrowband up to 4M bits/s. VSAT access satellite in
geosynchronous orbit to relay data from small earth station (terminals) to other
terminals (in mesh configuration) or master earth station ”hubs” (in star
A VSAT end user needs a box that interface between the user’s computer and
an outside antenna with a transceiver. The transceiver receives or sends a signal
to a satellite transponder in the sky. The satellite sends and receives signal from
an earth station computer that act as a hub for the system. Each end user is
interconnected with the hub station via the satellite in a star topology. For one
end users to communicate with another, each transmission has to first go to the
hub station, which retransmits it via the satellite to the other end users VSAT.
VSAT handles data, voice and video signals.
VSAT offers a number of advantages over terrestrial alternative for private
application companies can have total control of their own communication
system without dependence on their companies Business and home users get
higher speed reception than if using ordinary telephone services.
POWER LINE CARRIER COMMUNICATION
Apart from other modes of communication like telephone system, wireless etc.,
communication can also be established through the transmission line, which is
known as Power Line Carrier Communication (PLCC). This system provides
direct and independent communication between main plant and other
substations and load dispatch center of U.P. State Electricity Board (UPSEB)
grid. This will be exclusively used for communication in relation to Power
System Operation and control. The carrier communication system is coupled to
the 220KV power lines through coupling Capacitor Voltage Transformers
Public address System
A public address system(PA system) is an electronic amplification system
with a mixer, amplifier and loudspeakers, used to reinforce a sound source, e.g.,
a persongiving a speech, a DJ playing pre-recorded music, and distributing the
sound throughout a venue or building.
The simplest PA systems consist of a microphone, a modestly powered mixer
amplifier and one or more loudspeakers. Simple PA systems of this type, often
providing 50 to 200 watts of power, are often used in small venues such as
schoolauditoriums, churches, and small bars. A sound source such as a CD
player or radio may be connected to a PA system so that music can be played
through the system.
Public address systems typically consistof input sources, preamplifiers and/or
signal routers, amplifiers, controland monitoring equipment, and loudspeakers.
Input sources refer to the microphones and CD Players that provide a sound
input for the system. These input sources are fed into the preamplifiers and
signal routers that determine the zones to which the audio signal is fed. The
preamplified signals are then passed into the amplifiers. Depending on a
country's regulations these amplifiers will amplify the audio signals to 50V,
70V or 100V speaker line level. Control equipment monitors the amplifiers and
speaker lines for faults before it reaches the loudspeakers. This control
equipment is also used for separating zones in a PA system. The loudspeaker is
used to transduce electrical signals into analog sound signals.
Some PA systems have speakers that cover an entire campus of a college or
industrial site, or an entire outdoorcomplex (e.g., an athletic stadium). More
than often this PA system will be used as voice alarm system that make
announcement during emergency to evacuate the occupants in a building.
Telephone paging systems
Some analog or IP private branch exchange (PBX) telephone systems use a
paging facility that acts as a liaison between the telephone and a PA amplifier.
In other systems, paging equipment is not built into the telephone system.
Instead the system includes a separate paging controller connected to a trunk
port of the telephone system. The paging controller is accessed as either a
designated directory number or central office line. In many modern systems, the
paging function is integrated into the telephone system, and allows
announcements to be played over the phone speakers.
iii) Nuclear Physics
iv) NAPS STC guide