copy of nuclear disaster safety and precuation2003

7/31/2019 Copy of Nuclear Disaster Safety and Precuation2003

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NUCLEAR DISASTER SAFETY AND

PRECUATION


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WHY NUCLEAR POWER IS DANGEROUSTHAN OTHER POWER RESOURCES?

NUCLEAR RADIOACTIVE MATERIAL USED

WHICH IS HEALTH HAZARDOUS. ITCAN CAUSES SEVEREL HEALTHPROBLEMS. FROM CANCER TOOTHER NON CURABLE DISEASES.

IT NOT ONLY AFFECT THERADIATION EXPOSED PERSON, ITPASSES THROUGH GENERATIONS

IF THESE RADIOACTIVE MATERIALEXPOSED IN ENVIRONMENT INSIGNIFICANT AMOUNT THENUCLEAR PLANT AND ITSURROUNDING AREAS ARECOMPLETELY SHUT DOWN FORMANY DECADES.

OTHER NON-RENUABLE

NO SUCH PROBLEMSOTHER THAN CARBON DIOXIDE EMMISION


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SOME BRIF HISTORICAL FACTS THAT CHANGED THECOURSE OF NUCLEAR POWER AND THE SAFTY

MEASURMENT

IN 1951 FIRST NUCLEAR POWER PRODUCTION HAS BEEN DONE IN SOVIET RUSSIA

AFTER 1972 TO TILL DATE NO NEW REACTOR HAS BEEN MADE

1979 THE THREE MILE ISLAND DISASTER- NO CASULTIES, RADIATION CONTAINED

1986 THE CHERNOBYL DISATER

1988 ITALY DECLEARED NO NUCLEAR POWER PRODUCTION WILL HAPPEN THERE

2010 THE FUKUSHIMA DISATER

2010 GERMANY, ONE OF THE INDUSTRIALLY DEVOLPED COUNTRY TO ANNOUNCE THAT NUCLEAR POWERTO ABANDON ENERGY BY 2020.

ONLY THREE MAJOR ACCIDENTTO HAVE OCCURRED IN OVER 14500 CUMULATIVE REACTOR- YEARS OFOPERATION IN 32 COUNTRIES.


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THE BACKGROUND OF NUCLEARSAFETY

The three significant accidents in the 50-year history of civil nuclear power generation are:

Three Mile Island (USA 1979) where the reactor was severely damaged but radiation wascontained and there were no adverse health or environmental consequences

Chernobyl (Ukraine 1986) where the destruction of the reactor by steam explosion and firekilled 31 people and had significant health and environmental consequences. The death tollhas since increased to about 5

Fukushima (Japan 2011) where three old reactors (together with a fourth) were written off and the effects of loss of cooling due to a huge tsunami were inadequately contained

THESE THREE DISASTER CHANGED THE VIEWS ABOUT THENUCLEAR POWER AND RADICALLY CHANGED ITS SAFTY FEATURE
http://www.world-nuclear.org/info/inf36.htmlhttp://www.world-nuclear.org/info/chernobyl/inf07.htmlhttp://www.world-nuclear.org/info/fukushima_accident_inf129.htmlhttp://www.world-nuclear.org/info/fukushima_accident_inf129.htmlhttp://www.world-nuclear.org/info/chernobyl/inf07.htmlhttp://www.world-nuclear.org/info/inf36.html


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Where is it?

-- The Three Mile IslandNuclear GeneratingStation[TMI 2] in DauphinCounty, Pennsylvania nearHarrisburg, United States. When the reactor -2begin operation?

-- Feb 1978 When disaster happen?

---The accident began at4 a.m. on Wednesday,March 28, 1979

THREE MILE ISLAND DISASTER


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TMI-2core meltdown is a series of multiple event .

1. STUCK VALVE:1 of 8 condensate polisherspump feeding stopped .Bypass valves closed and 2 nd rys main feed water pump is notoperating and steam generatorsno longer receiving waterRising temperatures causedemergency valve to open torelease pressure

Due to loss of steam, water leveldrops, water overheats and burnsout pumpReactor core overheats and begins tomelt (a meltdown)

STEPTS OF ACCIDENT THAT LEAD TO CORE MELTDOWN:


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lack of a dedicated instrument to measure the level of water inthe core lead to faulty measurment.

operators turn off the emergency core cooling pumps

The quench tank relief diaphragm ruptured, and radioactivecoolant began to leak out into the general containment building

PORV was stuck open and the loss of coolant accident was still

in progress, primary coolant with fission products and/or fuelwas released, and ultimately ended up in the auxiliary building


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2. confusion over valve status:The design of the PORV indicator light was fundamentallyflawedThe unlighted lamp was actually misleading the operators byimplying that the valve was shut . But actually the valve wasopen then

A worker sees the open valve and closes it

To prevent an explosion, he reopens it, releasing radioactive steaminto the atmosphere

STEPTS OF ACCIDENT THAT LEAD TO CORE MELTDOWN:


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1.2B inlet

2.1A inlet3.Cavity4.Loose core debris5.Crust6.Previously molten material7.Lower plenum debris8.Possible region depleted inuranium9.Ablated incore instrument guide

10.Hole in baffle plate11.Coating of previously-moltenmaterial on bypass region interiorsurfaces12.Upper grid damage

TMI-2 Core End-State Configuration


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1979 Kemeny Commission fromMetropolitan Edison and NRCdata, a maximum of 13 million curies of radioactive noblegases(primarily xenon) werereleased by the event.However, these noble gases wereconsidered relativelyharmless, and only 13 17 curiesof thyroid cancer-causing iodine-131 were released.

Total releases according to thesefigures were a relatively smallproportion of theestimated 10 billion curies in thereactor.

Radioactive material release


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LESSONS LEARNED Nuclear reactor operator training has been improved It focused on reacting to an emergency by going

through a standardized checklist. improvements in quality assurance Improvements in control room habitability, "sight lines"

to instruments, ambiguous indications each nuclear site needed to have an approved

emergency plan to direct the evacuation of the publicwithin a ten mile Emergency Planning Zone (EPZ) and tofacilitate rapid notification and evacuation


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The Chernobyl disaster Where is it?

Chernobyl plant, which is nearthe city of Prypiat and within a closeproximity to the administrativeborder with Belarus and Dnieperriver in Ukranie(then Soviet Union) When the accident happen?

Saturday, 26 April 1986 atreactor number four.


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STEPS TO MELTDOWNIT WAS EXPERIMENT THAT TURNED

INTO CATASTROPHIC DISASTERAt 1:23:04 a.m. the experimentbegan. Four (of eight total) MainCirculating Pumps (MCP) wereactiveThe steam to the turbines was shutoff, and a run down of the turbinegenerator beganThe diesel generator started andsequentially picked up loads, whichwas complete by 01:23:43Momentum of the turbinegenerator decreased, the waterflow rate decreased, leading toincreased formation of steam voids(bubbles) in the core


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STEPS TO MELTDOWNAt 1:23:40, an emergency

shutdown of the reactorthis fully inserted all control rods,including the manual control rodsa massive power spike occurred,the core overheated.

seconds later this overheatingresulted in the initial explosionfuel rods fractured, blocking thecontrol rod columnsmassive steam buildup, leading toa rapid increase in steampressureA second, more powerfulexplosion occurred


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STEPS TO MELTDOWNthe second explosion resulted from a nuclear excursiona graphite fire broke out greatly contributing to the spread of radioactivematerial and the contamination of outlying areasSeveral hypothesis about the nature of the second explosion


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MAIN CAUSE OF THE ACCIDENT

The operator error was probably due to their lackof knowledge of nuclear reactor physics andengineering, as well as lack of experience and

trainingInsufficient communication between the safetyofficers and the operators in chargeFlaw in construction of the reactor


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RADIOACTIVE COMPONENT RELEASE All of the noble gases, including

krypton and xenon , containedwithin the reactor were released

55% of the radioactive iodine in thereactor, containing about 1760 P Bq or 400 kg of I-131, was released, asa mixture of vapor , solid particles,and organic iodine compounds.

Caesium (85 PBq Cs-137) andtellurium were released in aerosol form.

An early estimate for fuel materialreleased to the environment was 3 0.5%. This corresponds to theatmospheric emission of 6 t of fragmented fuel.

Total atmospheric release isestimated at 5200 P Bq.
http://en.wikipedia.org/wiki/Kryptonhttp://en.wikipedia.org/wiki/Xenonhttp://en.wikipedia.org/wiki/Iodinehttp://en.wikipedia.org/wiki/Bqhttp://en.wikipedia.org/wiki/Vaporhttp://en.wikipedia.org/wiki/Organoiodine_compoundhttp://en.wikipedia.org/wiki/Caesiumhttp://en.wikipedia.org/wiki/Telluriumhttp://en.wikipedia.org/wiki/Particulatehttp://en.wikipedia.org/wiki/Bqhttp://en.wikipedia.org/wiki/Bqhttp://en.wikipedia.org/wiki/Particulatehttp://en.wikipedia.org/wiki/Telluriumhttp://en.wikipedia.org/wiki/Caesiumhttp://en.wikipedia.org/wiki/Organoiodine_compoundhttp://en.wikipedia.org/wiki/Vaporhttp://en.wikipedia.org/wiki/Bqhttp://en.wikipedia.org/wiki/Iodinehttp://en.wikipedia.org/wiki/Xenonhttp://en.wikipedia.org/wiki/Krypton


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Areas of Europe contaminatedwith 137 Cs (km 2)

Country 37 185 kBq/m 2 185 555 kBq/m 2 555 1480 kBq/m 2 +1480 kBq/m 2

Belarus 29 900 10 200 4 200 2 200

Ukraine 37 200 3 200 900 600

Russia 49 800 5 700 2 100 300

Sweden 12 000 - - -Finland 11 500 - - -

Austria 8 600 - - -

Norway 5 200 - - -

Bulgaria 4 800 - - -

Switzerland 1 300 - - -

Greece 1 200 - - -Slovenia 300 - - -

Italy 300 - - -

Moldova 60 - - -

Totals 162 160 19 100 7 200 3 100
http://en.wikipedia.org/wiki/Kilogramhttp://en.wikipedia.org/wiki/Becquerelhttp://en.wikipedia.org/wiki/Belarushttp://en.wikipedia.org/wiki/Ukrainehttp://en.wikipedia.org/wiki/Russiahttp://en.wikipedia.org/wiki/Swedenhttp://en.wikipedia.org/wiki/Finlandhttp://en.wikipedia.org/wiki/Austriahttp://en.wikipedia.org/wiki/Norwayhttp://en.wikipedia.org/wiki/Bulgariahttp://en.wikipedia.org/wiki/Switzerlandhttp://en.wikipedia.org/wiki/Greecehttp://en.wikipedia.org/wiki/Sloveniahttp://en.wikipedia.org/wiki/Italyhttp://en.wikipedia.org/wiki/Moldovahttp://en.wikipedia.org/wiki/Moldovahttp://en.wikipedia.org/wiki/Italyhttp://en.wikipedia.org/wiki/Sloveniahttp://en.wikipedia.org/wiki/Greecehttp://en.wikipedia.org/wiki/Switzerlandhttp://en.wikipedia.org/wiki/Bulgariahttp://en.wikipedia.org/wiki/Norwayhttp://en.wikipedia.org/wiki/Austriahttp://en.wikipedia.org/wiki/Finlandhttp://en.wikipedia.org/wiki/Swedenhttp://en.wikipedia.org/wiki/Russiahttp://en.wikipedia.org/wiki/Ukrainehttp://en.wikipedia.org/wiki/Belarushttp://en.wikipedia.org/wiki/Becquerelhttp://en.wikipedia.org/wiki/Kilogram


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HUMAN CASULTY IT WAS THE ONLY ACCIDENT THAT

CAUSES SEVEREL HUMAN CASULTYBY DIRECT RADIOLOGICAL EXPOSURE237 people suffered from acuteradiation sickness (ARS), of whom 31

died within the first three monthsWithin four years at least 5,000 of themore than 600,000 decontaminationworkers had died from various causesroughly 100 plant personnel, Pripyatresidents, local farmers, coal minersand officials were killed in theimmediate aftermath of the disaster
http://en.wikipedia.org/wiki/Acute_radiation_sicknesshttp://en.wikipedia.org/wiki/Acute_radiation_sicknesshttp://en.wikipedia.org/wiki/Acute_radiation_sicknesshttp://en.wikipedia.org/wiki/Acute_radiation_sickness


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Assessing the disaster's effects onhuman health

Among the residents of Belarus,the Russian Federation andUkraine, there had been up to theyear 2005 more than 6,000 casesof thyroid cancer reported in

children and adolescents whowere exposed at the time of theaccident

Thyroid cancer incidence inchildren and adolescents fromBelarus after the Chernobyl

accident.Yellow: Adults (19 34)Blue : Adolescents (15 18)Red: Children (0 14)
http://en.wikipedia.org/wiki/Thyroid_cancerhttp://en.wikipedia.org/wiki/Thyroid_cancer


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Accident cause

11/03/2011, 2:46 p.m. localtime (7 hours earlier Romaniantime) near the Japanese islandof Honshu was an earthquakeof 9 on the Richter scale.

The quake had an impact onsection of north-east coast of Japan where they are located aseries of nuclear power plants(NPP).

Nuclear reactors have been shutdown properly.


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NPP DAIICHI before the earthquake


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Schematic of BOILING WATERREACTOR of NPP DAIICHI


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Event description 12.03. Units 4-6 in shut down status for periodic maintenance

and refuelling Units 1-3 were stopped automatically after the quake Reactor buildings and the containment successfully

resist to the earthquake All reactor were dissconnected from the external AC

supply Backup sources (diesel generators) started

At approximately one hour after the earthquake tsunamihit the site destroyed fuel tanks of the diesel generators flooded the diesel generator building

(10m protection wall was not sufficient) Mobile generators were sent to the site in a short time

but they ran out of fuel

Hydrogen Explosion Unit 1 Evacuation of population from the area of 20km DaiichiNPP and 10km Daina NPP (approx. 200 000 person)

On-site radioactivity increased


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Event description 13.03.

Lowering the internalpressure led to hydrogenexplosion at unit 3

Injection of sea water intothe reactor vessel withoutcooling units at unit 1-3

Variable on-site radioactivity

Increased radioactivity atOnagawa NPP (north of Daiichi) revealed that comesfrom Daiichi NPP


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Event description 14-15.03.

Cooling with seawater stopped at Unit 2 (unknown cause),variable water level in the reactor

Hydrogen Explosion at Unit 2 Cooling with sea water stopped at all units due to lack of fuel

and water source Fire then explosion in the spent fuel storage pool at unit 4

(relatively fresh fuel) Restart seawater injection in the reactor at all units Significant radioactive emission

Housing on the area of 20-30 km evacuated Risk of melting the core and damage of the containment at

Unit 2


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Daiichi NPP after hidrogen explosion 15.03.


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Fire in spent fuel storage pool at Unit 4, cooling waterevaporation

Water level decrease at Unit 5, taking water from Unit 6 Unsuccessfull attempts to feed with cooling water and boric

acid the spent fuel storage pool at Unit 4 Possible melting (at least partially, 50%) of the core at Units 1

and 3 Fill with water the reactor vessel of the Unit 2

Lowering water levels in the spent fuel pool at Units 3 and 4 Increasing temperature in the spent fuel pool at unit 5 and 6 Cooling with water canons from the police departement


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Daiichi NPP after hidrogen explosion(16.03.)


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Radioactivity observed outside of the site Fukushima: 3- 170 Sv / h (30 km from the NPP) In two places increasing dose 80 to 170, and 26 to 95 Sv/h Other directions 1- 5 Sv/h

Begining actions to connect a cable for AC supply tounit 2

Continue attempts for cooling Unit 4 with water fromhelicopters (without succes) then with water canons

One of the diesel generators from Unit 6 suppliesUnit 5 for cooling spent fuel storage pool and thereactor wessel


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Event description 18-19.03. An auxiliary transformer connected to external power source Actions to connect units 3 and 4 to AC power Actions to connect units 5 and 6 to AC power A backup generator from unit 6 repaired Continue seawater injection into the reactor vessel at Units 1-3 Cooling unit 3 with water canons provided by police and fire departement

units (civil defense, fire rescu units from Tokioand U.S. army), unit 3 isconsidered cooling enough

Considering additional cooling the spent fuel pools from Unit 4 At 5 AM, 19.03 starting pump C of the shutdown cooling system of unit 3,

used to cool the spent fuel storage pool. Restart cooling Unit 4 with water cannons, in collaboration with civil

defense.


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Continue works connect to the power supplyunits 3 and 4.

Continue cooling units 3 and 4with watercannons

Continue filling the spent fuel storage pools Water injection is continued in reactor vessels

of units 1-3


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Event description 20-21.03 Three holes are driven in the roof of reactor building units 5 and 6 to prevent hydrogen

accumulation At around 15.55 light gray smoke is observed from the southpart of the 5th floor of

Unit 3 Parameters of the reactor vessel and containment are not change significantly

Increase of radioactivity is subsequently found that returns to lower levels later For security reasons work is stoped and personnel withdraw from unit 3 Smoke changing color to white and slowly disappears Ends connecting a cable from the main transformer of the temporary substation. It begins to restore power supply of units 3, 4, 5 and 6 It restores the power supply from diesel generator of Unit 5 March 21 the presence of radioactivity in seawater is detected near southern discharge

channel near of the Daiichi NPP Cobalt, iodine and cesium is identified in seawater


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Ends cable connecting the power supply to unit 2, thesupply of of the entry side starts

White smoke seen in Unit 2, until the morning of 22.03 it disappears

White smoke at unit 3, disappears Continue water cooling units 2, 3 and 4, at unit 4 a

concrete pumping device is used to fill the spent fuel

storage pool Iodine and cesium is detected in the air at the site

sampling points


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Begins the injection of sea water in unit 2 using the normal cooling system Continue injecting sea water into unit 1 and 3 The power supply of units 1-6 is restored, the main control rooms are

connected to the AC supply

It began work on restoring power supply of the systems of all units Continue injecting seawater in the spent fuel storage pool of units 3 and 4 At 16.20, 23.03 a gray smoke is observed at unit 3, for security workers

from the control room and around Unit 3 are evacuated Smoke changes in white and disappears slowly Subsequently found that radioactivity is increasing and decrease more

slowly to the initial values End of water feed of the spent fuel storage pool of Unit 4


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Green smoke at Unit 3 (23.03.)


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Dose rates on the NPP site


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NUCLEAR SAFETY

WHAT IS IT?-- It covers the actions taken to prevent nuclearand radiation accidents or to limit their

consequences. This covers nuclear powerplants as well as all other nuclear facilities, thetransportation of nuclear materials, and the use

and storage of nuclear materials for medical,power, industry, and military uses.
http://en.wikipedia.org/wiki/Nuclear_and_radiation_accidentshttp://en.wikipedia.org/wiki/Nuclear_and_radiation_accidentshttp://en.wikipedia.org/wiki/Nuclear_power_plantshttp://en.wikipedia.org/wiki/Nuclear_power_plantshttp://en.wikipedia.org/wiki/Nuclear_power_plantshttp://en.wikipedia.org/wiki/Nuclear_power_plantshttp://en.wikipedia.org/wiki/Nuclear_and_radiation_accidentshttp://en.wikipedia.org/wiki/Nuclear_and_radiation_accidents


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SAFETY OF NUCLEAR POWER PLANT

WHAT IS THE HURDLE DESIGNING THE SAFETYFEATURES?

COMPLEX SYSTEMSFailure modes of nuclear power plantsVulnerability of nuclear plants to attack

Plant locationHazards of nuclear material


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OPTIMUM SAFETY As Nuclear power plant is very complex in nature it may

never be tagged as FULLY SAFE power. But we can achieve Optimum safety through DEFENCE IN

DEPTH mechanism. Most of the power plant is running thesemechanism

Key aspects of the approach are:

1 high-quality design & construction,

2 equipment which prevents operationaldisturbances or human failures and errorsdeveloping into problems,


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OPTIMUM SAFETY

3 comprehensive monitoring and regular testing todetect equipment or operator failures,

4 redundant and diverse systems to control

damage to the fuel and prevent significantradioactive releases,

5 provision to confine the effects of severe fueldamage (or any other problem) to the plant itself.


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Nuclear reactor safety systems

The three primary objectives of nuclear reactor safetysystems are

1. shut down the reactor,

2. maintain it in a shutdown condition, and3. prevent the release of radioactive material during

events and accidentsSeverel safety systems are incorporated in NUCLEAR

POWER PLANT over these years. And these systems designare constantly replaced by newar one/better one. Somebasic safety systems brifed next.


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Nuclear reactor safety systems1. Reactor protection system (RPS)

2. Essential service water system (ESWS)

3. Emergency core cooling system (ECCS)


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Emergency core cooling system (ECCS)

1-High pressure coolant injection system (HPCI)

2-Depressurization system

3-Low pressure coolant injection system (LPCI)

4-Isolation cooling system5-Emergency electrical systems

6- Containment systems


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Conclusion

1.Optimum safety of the Nuclear Power Plant isachieved by using defence in depthmechanism.

2. Development of more advanced Defence indepth mechanism to improve the reliabilityand safety of future Nuclear Power Plant

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