Insight of
Safety Features at KKNPP
General information
Under Operation, 20 Reactors, 4780 MW
Under Construction, 6 Reactors, 4800 MW
Proposed Projects
Location: The Kudankulam is
located on the coast of the Gulf
of Mannar, at 25 kM to the northeast from Kanyakumari,in Tamil
Nadu State.
Type: The Kudankulam Nuclear
Power Projects are world’s
most advanced VVER-1000
reactors designed by Russian
Engineers & Scientists.
Experience: The design has
been evolved from serial design
of VVER 1000 reactors, of
which 15 units are under
operation for last 25 years.
KKNPP: The VVER design
adopted at Kudankulam has in
additional many additional
unique safety features.
GENERAL INFORMATION :KKNPPs
•1000MWe.
•Coolant and
moderator Light water.
•Fuel -Enriched
uranium (up to
3.92%) as fuel.
•Coolant Four
loops
•Multi stateof-art reactor
protection and
safety systems
to handle all
the design
basis and
beyond design
basis events.
Safety features
1. Inherent safety.
2. Multiple Safety barriers
3. Redundant safety trains
4. Passive safety systems.
5. Active safety Systems
6. Safety culture
INHERENT SAFETY FEATURES
The VVER 1000 reactor chosen for Kudankulam
is inherent safe having features
 Negative power coefficient: Wherein any
increase in reactor power is self terminating.
 Negative Void Coefficient: reactor will shut
down, if there is loss of water.
Safety Barriers
Design safety incorporating defence-in-depth concept:
Five barrier system in the way of ionising radiation preventing release of radioactivity in
the environment
FUEL MATRIX
Prevent fission
product release
under fuel cladding
FUEL CLADDING
Prevent fission product
release into primary
(main circulation circuit)
coolant
MAIN CIRCULATION
CIRCUIT
Prevent fission product
release into
containment
INNER & OUTER
CONTAINMENT SYSTEM
Prevent fission product
release in the
environment
Five tiers of engineered features and administrative measures provided to
protect these barriers.
REDUNDANT SAFETYF TRAINS: 4No.
Four independent safety Trains even though one alone is
sufficient for the 100% safety of the reactor. System shown in
different four colours above are four independent train
7
ACTIVE SAFETY SYSTEMS
Emergency reactor
shutdown .
 Emergency boron
injection.
Containment spray.
High pressure safety
injection.
Primary system
emergency and
planed cool down and
fuel pool cooling.
Primary circuit shut
down cooling .
CONTAINMENT SYSTEMS
 Double Containment Buildings
 Primary Containment designed
for LOCA peak pressure of
0.4MPa.
 Passive
Hydrogen
recombiners for combustible gas
control inside the primary
containment
 Containment spray system for
pressure control.
 Secondary
Containment
designed for external effects,
such as missile attack, aircraft
crash & shock waves,
PASSIVE HEAT REMOVAL SYSTEM
Drag
shaft
Drag shaft
System
ensures longterm removal
of reactor
core decay
heat in
absence of all
power
supplies
Atmospheric
Atmospferic air
air
LOSS OF POWER
Steam
generator
Reactor
Atmospferic air
Atmospheric
air
PASSIVE HYDROGEN RECOMBINERS
PBLIC
INTERACTIONS
 Passively recombins the
hydrogen
 Thus maintains the
volumetric hydrogen
concentration in the
mixture below the safe
limits.
 Thereby avoid the
formation of the explosive
mixtures inside the
containment.
PASSIVE 1st & 2nd Stage
Hydro Accumulators
2nd Stage Hydro
Accumulators
1st Stage Hydro
Accumulators
 1st Stage Hydroaccumulators ensures
borated water supply
to the reactor core in
the event of loss of
coolant
Steam generator
RCP
RCP
Reactor
2nd
Stage Hydroaccumulators ensures
long term flooding of
reactor
core
with
borated
water
at
lower pressures.
QUICK BORON INJECTION
(PASSIVE SYSTEM)
Reactor
 System ensures
reactor shut down
 Injects high
concentration
borated water into
primary coolant by
inertial rotation of
cooling pumps .
LOSS OF POWER
hffhff
Quick acting
valve
Steam
generator
ГЦН
RCP
Boric
acid
tank
PASSIVE ANNULUS SPACE
DE-PRESSURIZING & FILTERING
Steam
generator
Atmospheric
air
Reactor
 System is intended
for controlled
removal of steamgas mix from the
annulus in case of
loss of all the
power.
 Sys maintains
vacuum and
cleaning fluid in
annular space.
 Inter-space kept at
Atmospheric negative pressure
air
to reduce releases
significantly.
CORE CATCHER
Confines molten core
within the containment
boundaries
in
the
hypothetical event of
melting of the reactor
core.
Supply of water to core catcher from settling
tanks located inside containment
1 – reactor;
1
4
2 – core catcher;
3
3 – fuel pool;
4 – monitor chamber
for reactor
internals;
5 – pipeline of water
supply to the
surface of molten
corium;
6
6 – water supply
pipeline from
external source
2
5
SG EMERGENCY COOLDOWN SYSTEM
Residual core
heat removal
during
Steam
generator
Reactor
loss of power
supply
loss of heat
removal through
the secondary
side.
Process
condenser
Pump
Provisions for withstanding external effects
involving earthquake, tsunami/storm, tidal
waves, cyclones, shock waves, fire and aircraft
impact on main buildings
18
RELATIVE ELEVATIONS OF SEA &
STRUCTURES AT KKNPP
SWITCH YARD
Design basis
flood level +
5.44 (MSL)
due to tidal
variations,
wave runup, storm
surge /
tsunami
REACTOR
PUMP
HOUSE
TURBINE
PUMP
+8.1m
DG 2
DG 4
+13m
DG 3
+8.7m
+9.3m
+7.65m
+5.44m
Tsunami of
26.12.2004
MEAN SEA LEVEL
170
-70
30
130
230
330
430
530
PROTECTIONS AGAINST TSUNAMI AT KKNPP
Kudankulam site is located far off (about 1500 km) from the
tsunamigenic fault (where tsunamis originate). Thus, if there is a
tsunami, it would take time and lose its energy by the time it
strikes Kudankulam site.
Where as against this, the tsunamigenic fault was only about 130
km away at Fukushima.
170
-70
Food Levels of important facilities at KKNPP
As compared to the Design Basis Flood Level of 5.44 meters,
levels of important facilities at KKNPP wiih respect to -mean sea
level are:
Reactor Building ground floor
8.7m
Safety diesel generator sets
9.3m
Switch gear for safety trains
9.3m
Group I battery bank
12.9m
Station blackout battery
16.5m
Control instruments for safety trains
16.5m
Supplementary control room
9.7m
STATUS ON
KUDANKULAM
PROJECT
Additional
protection
against
flooding
The supplementary control room and the four diesel
generator - safety train rooms are provided with water
tight doors to protect them against flooding. We should
normally ensure that the doors remain shut when the
reactors are operating by using interlocks or strict
administrative procedures.
STATUS ON KUDANKULAM PROJECT
With regard to earthquakes
Strongest one occurred at Coimbatore on February 8, 1900. The
India Meteorological Department estimated its magnitude at
6.0 on the Richter scale. The epicenter was little more than 300
km from Kudankulam. The nearest recorded was on August 25,
1856 near Trivandrum with an intensity estimated at 4.3 on the
Richter scale. Based on these observations, the parameters
chosen for design were:
Peak Ground Acceleration in g
Horizontal
Vertical
Design Basis - safe shutdown
0.15
0.11
Design Basis - operating
0.05
0.036
Automatic trip of the reactor is initiated at the vertical and
horizontal acceleration levels chosen for the operating basis
earthquake (namely 0.036 g vertical and 0.05 g horizontal)
STATUS
ON KUDANKULAM PROJECT
Grid connectivity
Kudankulam is connected to the southern grid at
Tirunelveli by double circuit 220 KV series and double
circuit 400 KV lines. Tuticorin thermal power station is
connected directly to Tirunelveli. There are a number
of hydro power stations in Kerala and Tamil Nadu close
to Kudankulam. We are having 10 MW of wind
turbines in our site
STATUS ON KUDANKULAM PROJECT
Decay Heat Removal
For cooling of the core in a shut down condition, to remove
the decay heat, four independent cooling trains, each with its
own diesel generator set, are provided. There is a back up
to this through hydro accumulators (in two stages).
Normally, the decay heat gets transferred to the secondary
side water. If the latter is not available for any reason. There
is a passive heat removal system where by the secondary
side water is cooled in air cooled heat exchangers. The
latter are located at a considerable height on the outer
containment to ensure natural circulation (i.e. it is a passive
system requiring no pumps or no power driven equipment).
This feature has been built into KKNPP design specifically at
India's insistence.
STATUS
KUDANKULAM
PROJECT
Safety
for ON
extreme
situation
There is a safety provision for an extreme situation of the fuel
in the core melting and breaching the pressure vessel. In
such a situation, the core catcher below the pressure vessel
will ensure that the molten core mixes with a large quantity of
neutron absorbing material and thus prevent the possibility of
a nuclear explosion. Only the most modern designs have
such a provision.
There are 154 passive hydrogen recombines to prevent any
explosive mixture forming in any zone of the primary
containment.