Safety Features at KKNPP

Safety Features at KKNPPInsight of

Location: The Kudankulam is located on the coast of the Gulf of Mannar, at 25 kM to the north-east 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.

Location: The Kudankulam is located on the coast of the Gulf of Mannar, at 25 kM to the north-east 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

Under Operation, 20 Reactors, 4780 MW Under Construction, 6 Reactors, 4800 MW Proposed Projects

GENERAL INFORMATION :KKNPPs

•1000MWe.•Coolant and moderator -Light water.

•Fuel -Enriched uranium (up to 3.92%) as fuel.

•Coolant Four loops •Multi state-of-art reactor protection and safety systems to handle all the design basis and beyond design basis events.

•1000MWe.•Coolant and moderator -Light water.

•Fuel -Enriched uranium (up to 3.92%) as fuel.

•Coolant Four loops •Multi state-of-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.

INNER & OUTER CONTAINMENT SYSTEMPrevent fission product release in the environment

FUEL MATRIXPrevent fission product release under fuel cladding

MAIN CIRCULATION CIRCUITPrevent fission product release into containment

FUEL CLADDINGPrevent fission product release into primary (main circulation circuit) coolant

Design safety incorporating defence-in-depth concept:Five barrier system in the way of ionising radiation preventing release of radioactivity in the environment

Safety Barriers

Five tiers of engineered features and administrative measures provided to protect these barriers.

REDUNDANT SAFETYF TRAINS: 4No.

7

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

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

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 .

Double Containment Buildings Primary Containment designed

for LOCA peak pressure of 0.4MPa.

Passive Hydrogen re-combiners 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,

CONTAINMENT SYSTEMS

Atmospferic air

LOSS OF POWER

Drag shaft

Atmospferic air

Drag shaft

Atmospheric air

Atmospheric air

System ensures long-term removal of reactor core decay heat in absence of all power supplies

Steamgenerator

Reactor

PASSIVE HEAT REMOVAL SYSTEM

PASSIVE HYDROGEN RECOMBINERS

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.

PBLIC INTERACTIONS

PASSIVE 1st & 2nd Stage Hydro Accumulators

1st Stage Hydro-accumulators ensures borated water supply to the reactor core in the event of loss of coolant

2nd Stage Hydro-accumulators ensures long term flooding of reactor core with borated water at lower pressures.

1st Stage HydroAccumulators

2nd Stage HydroAccumulators

Steam generator

Reactor

RCPRCP

hffhff

Boric acid tank

Quick acting valve

ГЦН

Reactor Steam generator

LOSS OF POWER

RCP

System ensures reactor shut down

Injects high concentration borated water into primary coolant by inertial rotation of cooling pumps .

QUICK BORON INJECTION (PASSIVE SYSTEM)

PASSIVE ANNULUS SPACE

DE-PRESSURIZING & FILTERING

System is intended for controlled removal of steam-gas 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 negative pressure to reduce releases significantly.

Steam generator

Reactor

Atmospheric air

Atmospheric air

CORE CATCHER

Confines molten core within the containment boundaries in the hypothetical event of melting of the reactor core.

1 – reactor;

2 – core catcher;

3 – fuel pool;

4 – monitor chamber for reactor internals;

5 – pipeline of water supply to the surface of molten corium;

6 – water supply pipeline from external source

Supply of water to core catcher from settling tanks located inside containment

1

2

34

56

SG EMERGENCY COOLDOWN SYSTEM

Residual core heat removal during

loss of power supply

loss of heat removal through the secondary side.

Steam generator

Reactor

Pump

Processcondenser

18

Provisions for withstanding external effects involving earthquake, tsunami/storm, tidal waves, cyclones, shock waves, fire and aircraft impact on main buildings

+5.44m

SWITCH YARD

DG 4DG 2

DG 3

REACTOR

+8.7m+8.1m

+9.3m

TURBINE

+7.65m

PUMPHOUSE

+13m

PUMP

Design basis flood level + 5.44 (MSL) due to tidal variations, wave run-up, storm surge / tsunami

MEAN SEA LEVEL

Tsunami of 26.12.2004

30 130 230 330 430 530-70170

RELATIVE ELEVATIONS OF SEA & STRUCTURES AT KKNPP

-70170

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.

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 8.7mSafety diesel generator sets 9.3mSwitch gear for safety trains 9.3mGroup I battery bank 12.9mStation blackout battery 16.5mControl instruments for safety trains 16.5mSupplementary control room 9.7m

STATUS ON KUDANKULAM PROJECT

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.

Additional protection against flooding

STATUS ON KUDANKULAM PROJECT

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:

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)

Peak Ground Acceleration in g Horizontal Vertical

Design Basis - safe shutdown 0.15 0.11

Design Basis - operating 0.05 0.036

With regard to earthquakes

STATUS ON KUDANKULAM PROJECT

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

Grid connectivity

STATUS ON KUDANKULAM PROJECT

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 outercontainment 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.

Decay Heat Removal

STATUS ON KUDANKULAM PROJECT

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.

Safety for extreme situation