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R. BHATTACHARYAAtomic Energy Regulatory Board

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Introduction

� Major industrial accidents- Flixborough, Bhopal, Texas, Gramercy Alumina, Mexico, HPCL-Vizag refinery, IOCL Jaipur fire

� Events- Fire, Explosions, Toxic releases

� Consequences- Injuries, Fatalities, Loss of property, Environmental degradation, Socio-economic problems

� Measures- State of the art Technology, Management Practices to prevent any disasters, Command and Control approach

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Flixborough Explosion, 1974

28 killed and 36 seriously injured

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Bhopal UC Plant, 19842,500 immediate fatalities;

Many other offsite injuries

Contaminated debris

HAZARD:Highly ToxicMethyl Isocyanate

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Texas Pasadena,1989Death of 23 persons& destruction of $750Million property.Release of extremelyflammable processgases that occurredduring regularmaintenance onpiping system led tofire and explosion.

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Gramercy Alumina Refinery, United

States,1999� Before accident After accident

29 persons injured & cause of explosion due to excessive build up of pressure 6

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Mexico City–Explosion, 1984

HAZARD: Flammable LPG in tank

300 killed(mostly offsite) $20M damage

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HPCL-Vizag refinery explosion,1997

� Fire broke out at 6:15 am, following a suspected leak in the LPG pipeline from the Vizag port to the storage farm.

� It caused a series of explosions, and soon spread to at least six other naphtha and petrol tanks.

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IOCL JAIPUR FIRE ,2009

12 people killed and injuring over 200 9

BP Refinery in Texas City, 2005

15 killed in massive explosion and 180 injured

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HPCL, VIZAG refinery Fire ,2013

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28 people killed

Why is Safety Needed?Port Kembla Ethanol Tank Fire, NSW, Australia, 28th January 2004

Quote from the Coroner…“not a lack of adequate safety procedures but rather the failure to adhere to them”.(Welding was carried out in an unsuitable area without a ‘hot work’ permit)

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Hazard Identification & Risk

Consequence Severity

Safety Report Influence

OH&S CatastrophicFire & Explosion

Maintenance

Protest picketsPersonal injuryIndustrial stoppage

High technology and high hazard system failuresClass actionsMarket collapseFatality (fatalities)

BreakdownsPublic criticismStaffcomplaints

Rela

tive F

req

uen

cy o

f Occu

rren

ce

Increasing risk

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Type of Risk assessment Qualitative

AssessmentHazard

Identification

Quantitative Risk Assessment Asset Integrity Studies

Plant Condition Analysis Human Factors Studies

Consequence AnalysisLikelihood Analysis

Technology Studies

Detailed Studies

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Consequences

� Most accident scenarios will involve at least one of the following outcomes:

– Loss of containment

– Loss of property

– Injury/illness to personnel

– Damage to environment

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Major Hazard and their Consequence�Major Hazard

o The storage and use of flammable, explosive or toxicchemicals having potential to cause death or seriousinjury to a large number of people, or cause extensivedamage to property or environment

�Consequences of major hazards could beformation of flammable vapour cloud, drifting ofcloud to a source of ignition, leading to a fire oran explosion or formation of toxic vapour cloudand drifting of the cloud to populated areas. Thiscan result in an Toxic releases or Fire & Explosion

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Toxicity� Refers to an affect on living organisms

� It is a measure of injury i.e damage to life or disturbance of biological function that follows exposure at some concentration.

� Acute Toxic

� Chronic Toxic

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Toxic Release�The effects of toxic chemicals when considering

major hazards are concerned with acute exposures

�Depending on exposure concentration and duration,toxic effects can be irreversible, impair the ability totake protective action or be life threatening

�Toxicity Indicators� TLV- TWA� TLV-C� STEL� IDLH� LC50

� LCLO� LD50

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Fire�The effect of fire on people is due to exposure to

thermal radiation

�The severity of burns depends on heat intensity and exposure time

�The secondary effects of fire can be depletion of oxygen or generation of toxic fumes.

�Types of fire:o Flash fire

o Pool fire

o Jet fire

o Vapour Cloud Explosion (VCE)

o Boiling Liquid Expanding Vapour Explosion (BLEVE)

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Explosion�Explosions are characterised by a shock wave or

pressure wave

�Cause damage to buildings, breaking of windows and ejecting missiles that can travel over large distances.

�Effects of over pressure can directly result in fatality but only in close vicinity

�Most of the fatalities and serious injuries in explosions are indirect effects of collapse of buildings, flying glass fragments and debris.

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Identification of Hazardous chemicals

that can cause major accidents�Based on the list of chemicals (684) and

associated threshold quantities specified in theMSIHC Rules, 1989

�Based on the toxic, flammable or explosiveproperties and their threshold quantitiesspecified in the MSIHC Rules

�Type of industries based on common experience

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Major Accident Hazard (MAH)

installation

As per the Manufacture, Storage & Import ofHazardous Chemical Rules (MSIHC), 1989 “MajorAccident Hazard (MAH) installation” means –isolated storage and industrial activities at a sitehandling (including transport through carrier orpipeline) hazardous chemicals equal to or, inexcess of threshold quantities specified in therelevant schedules of the rules.

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Typical MAH Installations� Petrochemical works and refineries

� Chemical works and chemical production plants

� LPG storage and terminals

� Stores and distribution centers for chemicals

� Large fertilizer stores

� Explosive factories

� Works in which chlorine is used in bulk quantities

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Methods of Hazard IdentificationClassification of Hazard Identification methods

� Comparative Methods: This method comparesdeviation from standard documents. These methodsidentify deviations from codes of practice or standardsand the deviations are potential hazards.

� Fundamental Methods: Fundamental methods are astructured way of stimulating a group of people toapply foresight in conjugation with their knowledge tothe task of identifying the hazards mainly by raising aseries of questions.

� Logic Diagram Methods: In these methods onlylogic is used to identify potential hazards

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Methods of Hazard Identification

�Check lists

�What If Analysis

� Hazard and Operability (HAZOP) Studies

�Failure Mode and Effects Analysis

�Dow Chemical Exposure Index

�Dow Fire and Explosion Index

�Fault and Event Tree Analysis

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Methods of Hazard Identification

Check ListIt is a systematic survey of topics important for plantsafety. They represent systematized experience andtherefore provide guidance for improving the safetyof the plant

What If? Analysiso The method involves asking a series of questions

beginning with this phrase for identifying hazards.o This is the “oldest” method of hazard identification.o The method is to ask questions such as

• what if pump fails?• what if temperature sensor fails?

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Methods of Hazard IdentificationHazard and Operability Studies (HAZOP)

o A multidisciplinary team makes a systematic survey of a process.

o For every part of the plant possible deviations from thedesign values, their causes, and their potentialconsequences are examined

o Thus the overview of possible accident-initiatingevents and weaknesses of the plant is obtained

Failure Mode and Effects Analysiso The important components considered, their failures

are postulated, and the expected consequences are assessed

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Methods of Hazard IdentificationDow’s Chemical Exposure Index (CEI)

� The CEI is a measure of the relative acute toxicity risk. It isused for initial process hazard analysis (PHA)

Dow Fire and Explosion Index� To evaluate the risk from fires and explosions caused by the

storage, handling , and processing of flammable,combustible, and reactive substances.

Fault Tree Analysis (FTA)� Graphical technique that provides a systematic

description of the combinations of possible occurrencesin a system, which can result in an undesirable outcome.

� This method can combine hardware failures and humanfailures

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Typical causes of Major Accidents

� Equipment / Component failure

� Human & Organizational errors

� Deviations from normal operating conditions

� External events

o Natural &

o Human-induced

� Malevolent acts

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Scenario SelectionThe scenario selection for emergency preparedness can be made based on the available national and international guidance.

� Sudden and complete rupture of pressure vessel,

� Guillotine breakage of pipe work connected to vessels,

� Small holes or cracks in piping and vessels,

� Failure of flange joints, and

� Failure of the glands and seals of pumps.

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Consequence Analysis� Estimate the source term based on the type of

release* (gas, liquid, 2-phase), rupture (leak, piperupture, catastrophic failure etc) postulated

� Estimate the transport of material in theenvironment

� Pool formation, its size, location and evaporation

� Gas dispersion from release, pool evaporation orflashing of liquid

� Release as fine solid particles leading to dustexplosion should also be considered for the powderscapable of causing dust explosion

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Consequence Analysis� Calculate the consequences of the hazardous chemical

release at the point of interest in terms ofo Concentration with respect to time at the point of interest for

toxic, asphyxiate or corrosive releaseso Incident heat flux and duration of fire for fireso Peak overpressures for explosions

� In case of a physical explosion, the stored energy in thevessel gives direct input for the calculation of effects (overpressure / shock wave)

� In case of a BLEVE and subsequent fire ball, the incidentthermal flux are directly determined by estimation of massinvolved in the fire ball

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Estimation of consequences

�Pool fire

�Vapor cloud explosion

� TNT equivalence method

� TNO multi-energy method

� Baker – Strehlow method

�Physical explosion

�Boiling Liquid Expanding Vapor Explosion (BLEVE)

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ExplosionRisk from fragments at a particular location is relatedto the number of fragments that may fall on or flythrough that location and their potential to dodamage, i.e. their mass and velocity

No accurate methods to predict the number offragments and their probable mass

Rough estimate by using pragmatic approach, basedon analysis of accidental explosions.

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Determination of effect zones� General Levels of concern for toxic chemicals

� IDLH, LC50, LD50 , ERPG

� General Levels of concern for effects of fire

� 1st degree burn (125 KJ/m2), 2nd degree burn ( 250 KJ/m2) & 3rd degree burn ( 350 KJ/m2)

� General Levels of concern for Explosion� The possible consequences of explosion depends on

the over pressure caused by it. �Unrepairable damage- 0.3 bar ( Heavy structure damage) is

considered for effect distance

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Hazard Control� Plant component design

� Static & Dynamic Loads, Corrosion, external events

� Safe Operation & Control systems� Automatic control, Interlocks, Alarms

� Safety Systems for protection from accidents� Pressure relief, Safe shutdown systems, Flare

� Maintenance and Monitoring of equipment� ISI, Ageing Management, Qualification of personnel

� Periodic inspection and repair� Supervision, procedures

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Measures to prevent accidents

� Management Support

� Training

� Follow of Standard Operating Procedures

� Implementation not just documentation

� Poorly laid out site increases risk of an accident

especially in MAH group of Industries

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Emergency Preparedness� Pre-impact activities that establish a state of readiness

to respond to extreme events that could affect theplant, personnel, property, general public and theenvironment

� Emergency Preparedness ensures that arrangementsare in place for a timely, managed, controlled,coordinated and effective response at the scene and atthe local, regional, national and international level

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Emergency Preparedness

Actions taken in case of an emergency

�Evacuation - Removal from further Exposure

�Sheltering through Breathing air shelters

�Administering of antidotes

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Emergency Management

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Mitigation Measures� In a major accident hazard installation, even if hazard

assessment is carried out and appropriate measures taken, thepossibility of an accident cannot be completely ruled out.

�For this reason it is apt to provide the measures, which canmitigate the consequences of an accident. Some of the protectivemeasures that can be taken to limit consequences are� Water jets & water spray systems (to cool tanks or to extinguish

fires)

� Collecting tanks, bunds, dikes etc (to prevent spread )

�Mitigation measures that can be administrative / procedural are� Set up and train fire brigade / incident response teams

� Provide alarm system with direct communication to incidentresponse team

� Provide antidotes in event of release of toxic substances

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Summary

�The major hazards in the facility shall be identified based on thehazardous properties and quantities of hazardous chemicalhandled in the facility

�The possible scenarios for emergency preparedness shall bedetermined based on various hazard identification techniquesand scenarios selection guidance

�consequence analysis of the selected scenarios shall be done todetermine the effect zones and sheltering requirements foremergency planning

�The reduction in impact due to major accidents should beachieved by provision of proper Hazard Control and MitigationMeasures.

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Conclusion

In order to control a major hazardsuccessfully, Management must haveanswers to the following:

�Do toxic, explosive or flammablesubstances in the facility constitute amajor hazard?

�Which failures or errors can causeabnormal conditions leading to a majoraccident?

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�If a major accident occurs, what are the consequences of a fire, an explosion or a toxic release for the employees, people living outside the facility or the environment?

�What can management do to prevent these accidents happening?

�What can be done to mitigate the consequences of an accident?

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