© K. Fedra 2000 1 Risk Assessment and Management technological and environmental risk analysis as a spatial DSS example

© K. Fedra 20001

Risk Assessment and Risk Assessment and ManagementManagement

Risk Assessment and Risk Assessment and ManagementManagement

technological and technological and environmental risk analysis environmental risk analysis as a spatial DSS exampleas a spatial DSS example

technological and technological and environmental risk analysis environmental risk analysis as a spatial DSS exampleas a spatial DSS example

© K. Fedra 20002

What is Risk ?What is Risk ?What is Risk ?What is Risk ?

thethe probability probability


© K. Fedra 20003

What is Risk ?What is Risk ?What is Risk ?What is Risk ?


of incurring a loss or injuryof incurring a loss or injury


of incurring a loss or injuryof incurring a loss or injury

© K. Fedra 20004

Different types of Risk:Different types of Risk:Different types of Risk:Different types of Risk:

• voluntary or involuntaryvoluntary or involuntary

• high-probability, low-consequencehigh-probability, low-consequence

• low-probability, high-consequencelow-probability, high-consequence

• individual or societalindividual or societal

• environmental or technologicalenvironmental or technological

• voluntary or involuntaryvoluntary or involuntary

• high-probability, low-consequencehigh-probability, low-consequence

• low-probability, high-consequencelow-probability, high-consequence

• individual or societalindividual or societal

• environmental or technologicalenvironmental or technological

© K. Fedra 20005

Different types of Risk Different types of Risk Management:Management:Different types of Risk Different types of Risk Management:Management:

• inactive (ignore it)inactive (ignore it)

• reactive (abatement)reactive (abatement)

• interactive (management)interactive (management)

• proactive (planning)proactive (planning)

• inactive (ignore it)inactive (ignore it)

• reactive (abatement)reactive (abatement)

• interactive (management)interactive (management)

• proactive (planning)proactive (planning)

© K. Fedra 20006

Different types of Risk Different types of Risk Management:Management:Different types of Risk Different types of Risk Management:Management:

• risk assessment and planningrisk assessment and planning identify, forecast, analyse, planidentify, forecast, analyse, plan

• operational risk abatementoperational risk abatement detect, diagnose, correctdetect, diagnose, correct

• risk assessment and planningrisk assessment and planning identify, forecast, analyse, planidentify, forecast, analyse, plan

• operational risk abatementoperational risk abatement detect, diagnose, correctdetect, diagnose, correct

© K. Fedra 20007

Estimating RisksEstimating RisksEstimating RisksEstimating Risks

A A GamingGaming approach: approach:

• probability of winning,probability of winning,

• amount to win,amount to win,

• probability of losing,probability of losing,

• amount to lose. amount to lose.

A A GamingGaming approach: approach:

• probability of winning,probability of winning,

• amount to win,amount to win,

• probability of losing,probability of losing,

• amount to lose. amount to lose.

© K. Fedra 20008


Expected value:Expected value: probability of loss or damageprobability of loss or damage magnitude of the lossmagnitude of the loss

VVexpexp = p(D) * V(D) = p(D) * V(D)

Expected value:Expected value: probability of loss or damageprobability of loss or damage magnitude of the lossmagnitude of the loss

VVexpexp = p(D) * V(D) = p(D) * V(D)

© K. Fedra 20009


Some problems:Some problems:• risk is about the unexpected: this risk is about the unexpected: this

means large inherent uncertaintiesmeans large inherent uncertainties

• low probability means little datalow probability means little data

• insurance can be expensive, insurance can be expensive, consider the opportunity costs consider the opportunity costs

Some problems:Some problems:• risk is about the unexpected: this risk is about the unexpected: this

means large inherent uncertaintiesmeans large inherent uncertainties

• low probability means little datalow probability means little data

• insurance can be expensive, insurance can be expensive, consider the opportunity costs consider the opportunity costs

© K. Fedra 200010

Environmental risksEnvironmental risksEnvironmental risksEnvironmental risks

• floods and droughtsfloods and droughts• hurricanes, typhoonshurricanes, typhoons• earthquakes, tsunamisearthquakes, tsunamis• mudslides, avalanchesmudslides, avalanches• forest firesforest fires• toxic fumes (Cameroon)toxic fumes (Cameroon)• climate change, sea level riseclimate change, sea level rise

• floods and droughtsfloods and droughts• hurricanes, typhoonshurricanes, typhoons• earthquakes, tsunamisearthquakes, tsunamis• mudslides, avalanchesmudslides, avalanches• forest firesforest fires• toxic fumes (Cameroon)toxic fumes (Cameroon)• climate change, sea level riseclimate change, sea level rise

© K. Fedra 200011

Technological risksTechnological risksTechnological risksTechnological risks

• fires and explosionsfires and explosions

• toxic chemicals releasetoxic chemicals release

- from process plants- from process plants

- from transportation accidents- from transportation accidents

• oil spillsoil spills

• nuclear accidentsnuclear accidents

• fires and explosionsfires and explosions

• toxic chemicals releasetoxic chemicals release

- from process plants- from process plants

- from transportation accidents- from transportation accidents

• oil spillsoil spills

• nuclear accidentsnuclear accidents

© K. Fedra 200012

Technological risksTechnological risksTechnological risksTechnological risks

• dioxin release (Seveso, 1976)dioxin release (Seveso, 1976)• gas explosion (Mexico, 1984)gas explosion (Mexico, 1984)• methylisocyanate (Bhopal, 1984)methylisocyanate (Bhopal, 1984)• toxic spill (River Rhine, 1986)toxic spill (River Rhine, 1986)• Chernobyl (reactor meltdown)Chernobyl (reactor meltdown)• Amocco Cadiz , Exxon ValdezAmocco Cadiz , Exxon Valdez (Oils spills)(Oils spills)

• dioxin release (Seveso, 1976)dioxin release (Seveso, 1976)• gas explosion (Mexico, 1984)gas explosion (Mexico, 1984)• methylisocyanate (Bhopal, 1984)methylisocyanate (Bhopal, 1984)• toxic spill (River Rhine, 1986)toxic spill (River Rhine, 1986)• Chernobyl (reactor meltdown)Chernobyl (reactor meltdown)• Amocco Cadiz , Exxon ValdezAmocco Cadiz , Exxon Valdez (Oils spills)(Oils spills)

© K. Fedra 200013

Industrial Safety ReviewIndustrial Safety ReviewIndustrial Safety ReviewIndustrial Safety Review

• Leadership and AdministrationLeadership and Administration• Management and TrainingManagement and Training• Job Analysis and ProceduresJob Analysis and Procedures• Emergency PreparednessEmergency Preparedness• Accident/Incident AnalysisAccident/Incident Analysis• Employee TrainingEmployee Training• Safety and Protective EquipmentSafety and Protective Equipment

• Leadership and AdministrationLeadership and Administration• Management and TrainingManagement and Training• Job Analysis and ProceduresJob Analysis and Procedures• Emergency PreparednessEmergency Preparedness• Accident/Incident AnalysisAccident/Incident Analysis• Employee TrainingEmployee Training• Safety and Protective EquipmentSafety and Protective Equipment

© K. Fedra 200014

Facility Emergency ResponseFacility Emergency ResponseFacility Emergency ResponseFacility Emergency Response

• Plant Emergency OrganizationPlant Emergency Organization• Plant Risk EvaluationPlant Risk Evaluation• Area Risk EvaluationArea Risk Evaluation• Notification Procedures, CommunicationNotification Procedures, Communication• Emergency Equipment and FacilitiesEmergency Equipment and Facilities• Procedure for return to normal operationsProcedure for return to normal operations


© K. Fedra 200015




© K. Fedra 200016


Plant Risk EvaluationPlant Risk Evaluation

• quantities, quantities, locationslocations, and storage , and storage conditions of hazardous materialsconditions of hazardous materials

• properties of materials (MSD sheets)properties of materials (MSD sheets)

• locationlocation of isolation valves of isolation valves

• fire fighting proceduresfire fighting procedures

• special handling requirementsspecial handling requirements

Plant Risk EvaluationPlant Risk Evaluation

• quantities, quantities, locationslocations, and storage , and storage conditions of hazardous materialsconditions of hazardous materials

• properties of materials (MSD sheets)properties of materials (MSD sheets)

• locationlocation of isolation valves of isolation valves

• fire fighting proceduresfire fighting procedures

• special handling requirementsspecial handling requirements

© K. Fedra 200017

Plant risk evaluationPlant risk evaluationPlant risk evaluationPlant risk evaluation

Site data baseSite data base includes basic includes basic administrative, technical, regulatoryadministrative, technical, regulatory

and safety relevant information:and safety relevant information:

hazardous chemicalshazardous chemicals

safety response planssafety response plans

and equipmentand equipment

Site data baseSite data base includes basic includes basic administrative, technical, regulatoryadministrative, technical, regulatory

and safety relevant information:and safety relevant information:

hazardous chemicalshazardous chemicals

safety response planssafety response plans

and equipmentand equipment

© K. Fedra 200019

Site data base examplesSite data base examplesSite data base examplesSite data base examples

© K. Fedra 200020


© K. Fedra 200021


© K. Fedra 200022

Plant risk evaluationPlant risk evaluationPlant risk evaluationPlant risk evaluation

Hazardous chemicals data base Hazardous chemicals data base includes includes substance identification data (names, substance identification data (names, synonyms, CAS, UN number), physical, synonyms, CAS, UN number), physical, chemical, and toxicological properties, chemical, and toxicological properties,

associates productionassociates production

processes and waste processes and waste

streams.streams.

Hazardous chemicals data base Hazardous chemicals data base includes includes substance identification data (names, substance identification data (names, synonyms, CAS, UN number), physical, synonyms, CAS, UN number), physical, chemical, and toxicological properties, chemical, and toxicological properties,

associates productionassociates production

processes and waste processes and waste

streams.streams.

© K. Fedra 200023

Hazardous chemicals DB Hazardous chemicals DB Hazardous chemicals DB Hazardous chemicals DB

© K. Fedra 200025

Facility Emergency ResponseFacility Emergency ResponseFacility Emergency ResponseFacility Emergency Response• Plant Emergency OrganizationPlant Emergency Organization• Plant Risk EvaluationPlant Risk Evaluation• Area Risk EvaluationArea Risk Evaluation• Notification Procedures, CommunicationNotification Procedures, Communication• Emergency Equipment and FacilitiesEmergency Equipment and Facilities• Procedure for return to normal operationsProcedure for return to normal operations

© K. Fedra 200026


Area Risk EvaluationArea Risk Evaluation• hazardous materials at nearby plantshazardous materials at nearby plants• nearby residences, population centers nearby residences, population centers

including schools, hospitals, nursing including schools, hospitals, nursing homes (evacuation procedures)homes (evacuation procedures)

• contacts at other sites (names, phone)contacts at other sites (names, phone)• notification proceduresnotification procedures

Area Risk EvaluationArea Risk Evaluation• hazardous materials at nearby plantshazardous materials at nearby plants• nearby residences, population centers nearby residences, population centers

including schools, hospitals, nursing including schools, hospitals, nursing homes (evacuation procedures)homes (evacuation procedures)

• contacts at other sites (names, phone)contacts at other sites (names, phone)• notification proceduresnotification procedures

© K. Fedra 200027

Hazards AnalysisHazards AnalysisHazards AnalysisHazards Analysis

a spatial approach:a spatial approach:

• evaluates the vulnerability of a evaluates the vulnerability of a geographical areageographical area, its population , its population and environment to technological and environment to technological risks (e.g., hazardous materials risks (e.g., hazardous materials release from process plants or release from process plants or transportation accidents) transportation accidents)

a spatial approach:a spatial approach:

• evaluates the vulnerability of a evaluates the vulnerability of a geographical areageographical area, its population , its population and environment to technological and environment to technological risks (e.g., hazardous materials risks (e.g., hazardous materials release from process plants or release from process plants or transportation accidents) transportation accidents)

© K. Fedra 200028

Hazards Analysis Hazards Analysis ChecklistChecklistHazards Analysis Hazards Analysis ChecklistChecklist

Has a hazards analysis been Has a hazards analysis been completed for this area ? completed for this area ?

When was it last updated ?When was it last updated ?Does the analysis include the Does the analysis include the

location, type, and amount of location, type, and amount of hazardous materials manufactured, hazardous materials manufactured, processed, stored, disposed within processed, stored, disposed within the area ?the area ?

Has a hazards analysis been Has a hazards analysis been completed for this area ? completed for this area ?

When was it last updated ?When was it last updated ?Does the analysis include the Does the analysis include the

location, type, and amount of location, type, and amount of hazardous materials manufactured, hazardous materials manufactured, processed, stored, disposed within processed, stored, disposed within the area ?the area ?

© K. Fedra 200029


Does it include transportation Does it include transportation routes of hazardous materials ?routes of hazardous materials ?

Have areas of public health Have areas of public health concern be identified ?concern be identified ?

Have sensitive environmental Have sensitive environmental areas been identified ?areas been identified ?

Does it include transportation Does it include transportation routes of hazardous materials ?routes of hazardous materials ?

Have areas of public health Have areas of public health concern be identified ?concern be identified ?

Have sensitive environmental Have sensitive environmental areas been identified ?areas been identified ?

© K. Fedra 200030


Have historical data on accidents Have historical data on accidents been collected and analyzed ?been collected and analyzed ?

Have levels of vulnerability been Have levels of vulnerability been identified for different areas ?identified for different areas ?

Are environmentally sensitive areas Are environmentally sensitive areas and population centers included in and population centers included in plant and transportation risk plant and transportation risk assessment ?assessment ?

Have historical data on accidents Have historical data on accidents been collected and analyzed ?been collected and analyzed ?

Have levels of vulnerability been Have levels of vulnerability been identified for different areas ?identified for different areas ?

Are environmentally sensitive areas Are environmentally sensitive areas and population centers included in and population centers included in plant and transportation risk plant and transportation risk assessment ?assessment ?

© K. Fedra 200031

Application examples:Application examples:Application examples:Application examples:

• simulation of atmospheric dispersion of simulation of atmospheric dispersion of toxic substances from transportation or toxic substances from transportation or process plant accidents.process plant accidents.

• uses local geographical, land use, and uses local geographical, land use, and

and population data to and population data to

estimate exposure andestimate exposure and

simulate evacuation simulate evacuation

plans.plans.

• simulation of atmospheric dispersion of simulation of atmospheric dispersion of toxic substances from transportation or toxic substances from transportation or process plant accidents.process plant accidents.

• uses local geographical, land use, and uses local geographical, land use, and

and population data to and population data to

estimate exposure andestimate exposure and

simulate evacuation simulate evacuation

plans.plans.

© K. Fedra 200032

Atmospheric release:Atmospheric release:Atmospheric release:Atmospheric release:

© K. Fedra 200033

Application examples:Application examples:Application examples:Application examples:

• simulation of aquatic spills of toxics.simulation of aquatic spills of toxics.• uses chemical properties together with uses chemical properties together with

hydrological data, estimates the hydrological data, estimates the concentration of the chemical along theconcentration of the chemical along the

river and over time.river and over time. Can use an embeddedCan use an embedded expert system toexpert system to estimate environmentalestimate environmental damage.damage.

• simulation of aquatic spills of toxics.simulation of aquatic spills of toxics.• uses chemical properties together with uses chemical properties together with

hydrological data, estimates the hydrological data, estimates the concentration of the chemical along theconcentration of the chemical along the

river and over time.river and over time. Can use an embeddedCan use an embedded expert system toexpert system to estimate environmentalestimate environmental damage.damage.

© K. Fedra 200034

Aquatic spill:Aquatic spill:Aquatic spill:Aquatic spill:

© K. Fedra 200035

Risk Planning: Risk Planning: Regulatory frameworksRegulatory frameworksRisk Planning: Risk Planning: Regulatory frameworksRegulatory frameworks

• safety audits, regular inspectionssafety audits, regular inspections• chemicals registrychemicals registry• waste managementwaste management• transportationtransportation safetysafety• emergencyemergency planningplanning• zoningzoning

• safety audits, regular inspectionssafety audits, regular inspections• chemicals registrychemicals registry• waste managementwaste management• transportationtransportation safetysafety• emergencyemergency planningplanning• zoningzoning

© K. Fedra 200036

Regulatory frameworksRegulatory frameworksRegulatory frameworksRegulatory frameworks

European Union:European Union:

The Directive on Major Accident The Directive on Major Accident

Hazards of Certain Industrial Activities Hazards of Certain Industrial Activities

(Seveso Directive)(Seveso Directive)Council Directive of June 24, 1982 (82/501/EEC), Council Directive of June 24, 1982 (82/501/EEC),

Official Journal of the European Communities, Official Journal of the European Communities, L230, Vol.25, August 5, 1982.L230, Vol.25, August 5, 1982.

European Union:European Union:

The Directive on Major Accident The Directive on Major Accident

Hazards of Certain Industrial Activities Hazards of Certain Industrial Activities

(Seveso Directive)(Seveso Directive)Council Directive of June 24, 1982 (82/501/EEC), Council Directive of June 24, 1982 (82/501/EEC),

Official Journal of the European Communities, Official Journal of the European Communities, L230, Vol.25, August 5, 1982.L230, Vol.25, August 5, 1982.

© K. Fedra 200037

Seveso DirectiveSeveso DirectiveSeveso DirectiveSeveso Directive

Background:Background:

industrial accidents industrial accidents (Seveso, Flixborough)(Seveso, Flixborough)

characterised by a lack of information characterised by a lack of information (substances and amounts involved) by (substances and amounts involved) by the local authorities, and lack of the local authorities, and lack of emergency planning.emergency planning.

Background:Background:

industrial accidents industrial accidents (Seveso, Flixborough)(Seveso, Flixborough)

characterised by a lack of information characterised by a lack of information (substances and amounts involved) by (substances and amounts involved) by the local authorities, and lack of the local authorities, and lack of emergency planning.emergency planning.

© K. Fedra 200038


Objective:Objective:

improve the generation and control of improve the generation and control of correct correct information information flow among the flow among the actors in the risk management actors in the risk management procedure (industrial activities that procedure (industrial activities that process or store hazardous materials).process or store hazardous materials).

Objective:Objective:

improve the generation and control of improve the generation and control of correct correct information information flow among the flow among the actors in the risk management actors in the risk management procedure (industrial activities that procedure (industrial activities that process or store hazardous materials).process or store hazardous materials).

© K. Fedra 200039


Provisions:Provisions:• states must appoint a competent authoritystates must appoint a competent authority

• operators must prove to the CA operators must prove to the CA

– major hazards have been identifiedmajor hazards have been identified

– safety measures have been taken to safety measures have been taken to prevent accidentsprevent accidents

Provisions:Provisions:• states must appoint a competent authoritystates must appoint a competent authority

• operators must prove to the CA operators must prove to the CA

– major hazards have been identifiedmajor hazards have been identified

– safety measures have been taken to safety measures have been taken to prevent accidentsprevent accidents

© K. Fedra 200040


when hazardous substance inventories when hazardous substance inventories exceed thresholds:exceed thresholds:

• operator provides CA with Safety Reportoperator provides CA with Safety Report

• prepares internal emergency planprepares internal emergency plan

• provides information to CA for off-site provides information to CA for off-site emergency planemergency plan

• CA is notified of any major modificationCA is notified of any major modification

when hazardous substance inventories when hazardous substance inventories exceed thresholds:exceed thresholds:

• operator provides CA with Safety Reportoperator provides CA with Safety Report

• prepares internal emergency planprepares internal emergency plan

• provides information to CA for off-site provides information to CA for off-site emergency planemergency plan

• CA is notified of any major modificationCA is notified of any major modification

© K. Fedra 200041


• CA provides for external emergency CA provides for external emergency planningplanning

• states ensure that people potentially states ensure that people potentially affected by an accidents are actively affected by an accidents are actively informed on safety measuresinformed on safety measures

• operators report any major accidentoperators report any major accident

• states notify the Commissionstates notify the Commission

• Commission keeps a register of accidentsCommission keeps a register of accidents

• CA provides for external emergency CA provides for external emergency planningplanning

• states ensure that people potentially states ensure that people potentially affected by an accidents are actively affected by an accidents are actively informed on safety measuresinformed on safety measures

• operators report any major accidentoperators report any major accident

• states notify the Commissionstates notify the Commission

• Commission keeps a register of accidentsCommission keeps a register of accidents

© K. Fedra 200042

Risk AssessmentRisk AssessmentRisk AssessmentRisk Assessment

Zoning andZoning and

land-useland-use

planningplanning

based onbased on

externalexternal

safetysafety

report.report.

Zoning andZoning and

land-useland-use

planningplanning

based onbased on

externalexternal

safetysafety

report.report.

© K. Fedra 200043


Risk contours aroundRisk contours arounda plant location:a plant location:

1010-6-6 events/year events/year unacceptableunacceptable individual riskindividual risk

1010-8 -8 events/yearevents/year negligible risknegligible risk

Risk contours aroundRisk contours arounda plant location:a plant location:

1010-6-6 events/year events/year unacceptableunacceptable individual riskindividual risk

1010-8 -8 events/yearevents/year negligible risknegligible risk

© K. Fedra 200044


Risk levels Risk levels (the Dutch perspective)(the Dutch perspective)

1010-4-4 events/year: voluntarily accepted in events/year: voluntarily accepted in daily lifedaily life

1010-5 -5 events/year: maximum tolerableevents/year: maximum tolerable total involuntary risktotal involuntary risk

1010-6-6 events/year: unacceptable involuntary events/year: unacceptable involuntary from a single sourcefrom a single source

1010-8 -8 events/year: negligible riskevents/year: negligible risk

Risk levels Risk levels (the Dutch perspective)(the Dutch perspective)

1010-4-4 events/year: voluntarily accepted in events/year: voluntarily accepted in daily lifedaily life

1010-5 -5 events/year: maximum tolerableevents/year: maximum tolerable total involuntary risktotal involuntary risk

1010-6-6 events/year: unacceptable involuntary events/year: unacceptable involuntary from a single sourcefrom a single source

1010-8 -8 events/year: negligible riskevents/year: negligible risk

© K. Fedra 200045

Risk analysis procedureRisk analysis procedureRisk analysis procedureRisk analysis procedure

• Hazard identificationHazard identification

• Accident frequency and Accident frequency and consequence estimationconsequence estimation

• Risk calculationRisk calculation

• Risk reduction and acceptabilityRisk reduction and acceptability

• Hazard identificationHazard identification

• Accident frequency and Accident frequency and consequence estimationconsequence estimation

• Risk calculationRisk calculation

• Risk reduction and acceptabilityRisk reduction and acceptability

© K. Fedra 200046


Hazard Identification (HAZID)Hazard Identification (HAZID)• Process/system checklistProcess/system checklist

• Safety reviewSafety review

• Preliminary Hazard AnalysisPreliminary Hazard Analysis

• Failure Mode and Effects Analysis (FMEA)Failure Mode and Effects Analysis (FMEA)

• Hazard and Operability Analysis (HAZOP)Hazard and Operability Analysis (HAZOP)

• Systematic Identification of Release PointsSystematic Identification of Release Points

Hazard Identification (HAZID)Hazard Identification (HAZID)• Process/system checklistProcess/system checklist

• Safety reviewSafety review

• Preliminary Hazard AnalysisPreliminary Hazard Analysis

• Failure Mode and Effects Analysis (FMEA)Failure Mode and Effects Analysis (FMEA)

• Hazard and Operability Analysis (HAZOP)Hazard and Operability Analysis (HAZOP)

• Systematic Identification of Release PointsSystematic Identification of Release Points

© K. Fedra 200047


Frequency and Consequence Frequency and Consequence Estimation:Estimation:

• Fault treeFault tree

• Event treeEvent tree

• Cause Consequence DiagramCause Consequence Diagram

• Generic Reliability DatabaseGeneric Reliability Database

Frequency and Consequence Frequency and Consequence Estimation:Estimation:

• Fault treeFault tree

• Event treeEvent tree

• Cause Consequence DiagramCause Consequence Diagram

• Generic Reliability DatabaseGeneric Reliability Database

© K. Fedra 200048


Fault tree analysis: run-away Fault tree analysis: run-away reaction due to cooling failurereaction due to cooling failure

Fault tree analysis: run-away Fault tree analysis: run-away reaction due to cooling failurereaction due to cooling failure

© K. Fedra 200049


Failure of:Failure of:

heating systemheating system

sensorsensor

shutdown systemshutdown system

cooling systemcooling system

safety valvesafety valve

Failure of:Failure of:

heating systemheating system

sensorsensor

shutdown systemshutdown system

cooling systemcooling system

safety valvesafety valve

© K. Fedra 200050


Event tree: traces possible events fromEvent tree: traces possible events from

loss of cooling loss of cooling to: to: safe shutdownsafe shutdown

discharge fromdischarge from safety valvesafety valve

explosionexplosion

Event tree: traces possible events fromEvent tree: traces possible events from

loss of cooling loss of cooling to: to: safe shutdownsafe shutdown

discharge fromdischarge from safety valvesafety valve

explosionexplosion

© K. Fedra 200051


Every event Every event AA has possible outcome has possible outcome

C C (with probability: p) and (with probability: p) and B B (1-p)(1-p)

dependingdepending

on failureon failure

probabilityprobability

Every event Every event AA has possible outcome has possible outcome

C C (with probability: p) and (with probability: p) and B B (1-p)(1-p)

dependingdepending

on failureon failure

probabilityprobability

© K. Fedra 200052


Consequences:Consequences:• discharge (flow, evaporation)discharge (flow, evaporation)• fire: jet, pool/tank, flash, fireballfire: jet, pool/tank, flash, fireball• explosion and release:explosion and release:

– unconfined vapor cloud (UVCE)unconfined vapor cloud (UVCE)– boiling liquid expanding vapor explosion (BLEVE)boiling liquid expanding vapor explosion (BLEVE)– physical explosionphysical explosion– runaway reaction explosionrunaway reaction explosion– dust gas/dust mixture explosiondust gas/dust mixture explosion

Consequences:Consequences:• discharge (flow, evaporation)discharge (flow, evaporation)• fire: jet, pool/tank, flash, fireballfire: jet, pool/tank, flash, fireball• explosion and release:explosion and release:

– unconfined vapor cloud (UVCE)unconfined vapor cloud (UVCE)– boiling liquid expanding vapor explosion (BLEVE)boiling liquid expanding vapor explosion (BLEVE)– physical explosionphysical explosion– runaway reaction explosionrunaway reaction explosion– dust gas/dust mixture explosiondust gas/dust mixture explosion

Documents

© K. Fedra 2000 1 Risk Assessment and Management technological and environmental risk analysis as a spatial DSS example