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This project is funded by the European Union Projekat finansira Evropska Unija. INTRODUCTION TO RISK ASSESSMENT AND MANAGEMENT Antony Thanos Ph.D. Chem. Eng. [email protected] Risk assessment The procedure of evaluation of risk level

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Introduction to risk assessment and management antony thanos ph d chem eng antony thanos@gmail com

This project is funded by the European Union

Projekat finansira Evropska Unija

INTRODUCTION TO RISK ASSESSMENT AND MANAGEMENT Antony ThanosPh.D. Chem. [email protected]


  • Risk assessment

    • The procedure of evaluation of risk level

    • The heart of Safety Report and Safety Management System

  • Basic Terms in Risk Assessment

    • Hazard

    • Accident

    • Consequence

    • Risk


  • Hazard definitions

    • Generic : State, action or physical/chemical characteristic with potential of harm to equipment, human health or the environment

    • Seveso III Directive (art.3 para.14) : “the intrinsic property of a dangerous substance or physical situation, with a potential for creating damage to human health or the environment”

    • Rulebook : “intrinsic properties of dangerous substances or a set of certain circumstances in relation to dangerous substances which may causeharmful effects for human health and environment”


  • Common characteristics for hazard definitions :

    • hazard relates to potential of harm, not to necessity or to probability (high/low)of hazard to be expressed (accident)

    • hazard is related to effects on human health and environment

  • In Seveso Directive and Rulebook, indirectly relation of hazardtoequipment damage via Domino effects analysis


  • Hazard examples :

    • Work at height – Hazard of fall

    • Toxic material handling (e.g. production of NH3)

      • Toxic release (e.g. failure of pipe)

      • Dispersion of released NH3 to the atmosphere

      • Toxic effects to human via inhalation of toxic substance

  • Hazard source example : mechanical failures, e.g. corrosion, weld defects


  • Accident definitions

    • Generic : The event that leads to harm to human, environment or equipment

    • Seveso III Directive art.3 para.13 : “major accident means an occurrence such as a major emission, fire, or explosion resulting from uncontrolled developments in the course of the operation of any establishment covered by this Directive, and leading to serious danger to human health or the environment, immediate or delayed, inside or outside the establishment, and involving one or more dangerous substances”



  • Consequence : The outcome (effect) of an accident, as for example:

    • Injury from fall from height

    • Pulmonary damage due to inhalation of released NH3

    • Burns from thermal radiation of fire in gasoline tank

  • Consequence analysis : the procedure applied for calculation of the extent of accidents effects


  • The effect levels have to be defined (e.g. death, 1st degree burn, collapse of house) for estimation of extent of consequences

  • Extent of consequences is usually estimated as distance from accident centre for the expected effect level

  • Consequence results presentation usually in graphs, tables, maps


  • Relation of Hazard Identification / Accident / Consequence analysis

    • Hazard identification : Use of techniques for identifying hazards, causes of accidents and effects

    • Accidents usually related with primary hazardous substance release via Loss of Containment (LoC)

    • Hazard identification usually specify releaseexpected and not final accident (top event)

    • Top event required for consequence analysis


  • Relation of Hazard Identification / analysisAccident / Consequence analysis (cont.)

    • Hazard identification result example :

      • Leak of LPG from transfer pump seal

    • Top event accidents examples :

      • Jet flame from leak of LPG from pump seal

      • Flash fire from leak of LPG from pump

    • Consequence analysis results examples :

      • Thermal radiation 1500 TDUs at 50 m from LPG pump

      • Low Flammability Levelat 180 m downwind LPG pump location



  • Individual Risk : Risk of analysiscertain level of harm from accident, at specific location, independent of number of affected subjects

    • Example : The risk of lethal effects from thermal radiationfrom pool fire in gasoline tank TK-123 of factory ABC is calculated as 10-6 per year at a distance of 100 m from tank. No interest on how many people can be present in 100 m location.


  • Societal Risk : analysis

    • Relationship between frequency of accident and number of people suffering from a specified level of harm in a given population from the realisation of specified accidents

    • Concerns estimation of the chances of more than one individual being harmed simultaneously by an incident



  • Seveso III Directive definition of risk analysis

    • art.3 para.15 : “risk means the likelihood of a specific effect occurring within a specified period or in specified circumstances”

    • Noreference to quantitative or qualitativeexpression of risk

    • No reference to severity of effect (injury, lethal effects etc.)

    • No reference to individual or societal risk

    • No reference to risk acceptancecriteria


  • Rulebook references to risk : analysis

    • “The probability shall be numericallyordescriptively expressed as low, medium and high…

    • Accident risk shall be assessed on the basis of accident probability and potential consequences. Chemical accident risk shall be expressed as: negligible, low, medium, high and very high, in accordance with criteria shown in the following table…”


Hazard

Identification

Accident

Scenarios

Consequence

Analysis

Accident

Probability

Risk reduction

measures

NO

YES

Accepted

Risk

Risk

Assessment

END


  • Safety Report purpose in Seveso III Directive analysis

    • art.10 para.1.b :“Demonstrating that major-accident hazards and possiblemajor-accident scenarios have been identified and that the necessary measures have been taken to prevent such accidents and to limit their consequencesfor human health and the environment.”


  • Safety Report purpose in Seveso III Directive (cont.) analysis

    • art.10 para.1.c : “Demonstrating that adequate safety and reliability have been taken into account in the design, construction, operation and maintenance of any installation, storage facility, equipment and infrastructure connected with its operation which are linked to major-accident hazards inside the establishment.”


  • Safety Report purpose in Seveso III Directive (cont.) analysis

    • Demonstration

      • Justification (convince assessor) of results

      • No absolute proofs possible / Uncertaintyexpected on results

      • Professional judgement expected on credibility of results

      • Evidence that a systematic methodology is used (direct relation with Safety Management System requirement for risk assessment and management of change)


  • Safety Report purpose in Seveso III Directive (cont.) analysis

    • Demonstration

      • The level of demonstration should be proportionate to the extent of potential consequences and the complexity of the installation/process/systems involved.

        • Common approach in Major Accident Hazard Bureau (MAHG) Guidance and Member State Guidance documents (e.g. UK Health and Safety Executive –HSE- Safety Report Assessment Guide –SRAG- Document)



  • Safety Report purpose in Seveso III Directive (cont.) analysis

    • Demonstration vs Proof (art.5. para.2) :“Member States shall ensure that the operator is required to prove to the competent authority referred to in Article 6, at any time, in particular for the purposes of inspections and controls referred to in Article 20, that the operator has taken all necessary measures as specified in this Directive.”

    • Proof focused within inspection activities


  • Safety Report purpose in Seveso III Directive (cont.) analysis

    • art.10 para.1.e : “Providing sufficient information to the competent authority to enable decisions to be made regarding the siting of new activities or developments around existing establishments.”

    • Safety Report is a tool for :

      • Permit procedures

      • Land Use Planningprior to establishment of an installation

      • Land Use Planningin the area of existing establishments


  • Hazard identification analysis(internal)

    • Seveso III, Annex II para 2.b :“Identification of installations and other activities of the establishment which could present a major-accident hazard”

    • Major Accident Hazard Bureau (MAHR) Guidance of Safety Report :

      • Possible selection of installation via screening methods

      • Reference to index methods or threshold criteria for hazardous substances or other suitable methods


  • Hazard identification analysis(internal) (cont.)

    • No clear methodology on selection of activities

    • Screening methods inherently do not take into account Domino effects

      • Very small LPG tank failure could be neglected as initiating BLEVE in close-by much bigger tank


  • Hazard identification analysis(external)

    • Seveso III, Annex II para 2.c : “On the basis of available information, identification of neighbouring establishments, as well as sites that fall outside the scope of this Directive, areas and developments that could be the source of, or increase the risk or consequencesof a major accident and of domino effects”

      • External Domino

      • Identification of potential source for secondary accidents


  • Hazard identification analysis(external) (cont.)

    • Available information

      • No requirements for risk assessment in Third Party installations

      • Authorities should coordinate informationexchange between installations

      • Absence of information in case of out-of (Seveso Directive) scope neighbours (as no risk assessment required for them)


  • Hazard identification analysisand locations

    • Seveso III Directive, Annex II para 2.d : “description of areas where a major accident may occur”

    • Same problems as with installation identification



  • I analysisdentification of accidents and risk analysis

    • Seveso III Directive,Annex II para.4.a : “detailed description of the possible major-accident scenarios and their probability or the conditions under which they occur including a summary of the events which may play a role in triggering each of these scenarios, ….”

      • Possible : on what basis ? Which scenario is not considered as impossible ? (very low probability, history ?)

      • Possible vs “credible” scenario dilemma


  • I analysisdentification of accidents and risk analysis (cont.)

    • “probability or conditions”… No clear requirement for probability (either qualitative or quantitative)

    • No requirements for specific hazard identification/accident selection methods

    • Member States guidance define the type of assessment (including requirements for probabilities) and implementation details


  • I analysisdentification of accidents and risk analysis (cont.)

    • Seveso III Directive,Annex II para.4.c) : “Review of past accidents and incidents with the same substances and processes used, consideration of lessons learned from these, and explicit reference to specific measurestaken to prevent such accidents”

      • Simple submission of a printout of past accidents listdoes not contribute to establishment safety status

      • Lessons learnt expected to had been applied in establishment


  • Essential information expected for scenarios selection and description

    • Methodology applied, including criteria for selection of accidents to be used in Consequence Analysis

    • Description of scenarios, including :

      • duration type (instantaneous, specific duration, continuous),

      • size of release (equivalent “hole”)

      • top events expected


  • Consequence analysis description

    • Seveso III Directive,Annex II para.4.b : “assessment of the extent and severity of the consequences of identified major accidents including maps, images or, as appropriate, equivalent descriptions, showing areas which are likely to be affected by such accidents arising from the establishment”


  • Consequence analysis description(cont.)

    • Clear statement that accident should arise from establishment (no interest in consequence from accidents in neighbour establishments which could cause Domino effects)

    • No requirements for methodologies of consequence analysis

    • No definition of consequence level in interest (incl. Domino effects)


  • Consequence analysis description(cont.)

    • Indirect reference to some consequence levels related to major accidents in Directive Annex VI (accident reporting to Commission), as for example : 1 death, 6 injuries in establishment, 1 injury outside establishment, dwellings (outside establishment)damaged and unusuable…

    • Annex VI should not be straightforward used for consequence levels definition

    • Member States Guidance documents, or legislation (e.g. France, Italy) define the consequence end-points to be used


  • Accident control, prevention and mitigation ( descriptionSeveso III Directive,Annex II)

    • para.4.d : “description of technical parameters and equipment used for the safety of installation”

    • para.5.a : “description of the equipment installed in the plant to limit the consequences of major accidents for human health and environment, including …..”

    • para.5.d : “description of any technical and non-technical measures relevant for the reduction of the impact of a major accident”


  • Accident control, prevention and mitigation description

    • Measures for safety of installation (safety barriers) to be considered:

      • Control measures

        • Monitoring equipment (e.g. local/remote instruments for operating parameters monitoring)

        • Process control systems regulating operating conditions, such as pressure

        • Emergency Shut Down (ESD) systems


  • Accident control, prevention and mitigation (cont.) description

    • Measures for safety of installation(cont.)

      • Prevention measures

        • Design basis/standards

        • Active prevention equipment (e.g. Pressure Relief Valves preventing equipment failure due to overpressure)

        • Passive prevention equipment (e.g. safety dikes)

        • Procedures (e.g. vessel/tanks inspection procedures)


  • Accident control, prevention and mitigation (cont.) description

    • Measures for safety of installation(cont.)

      • Mitigation measures (passive/active), such as :

        • fire protection measures/equipment (fire resistant structures, fire monitors etc.)

        • oil spill contingency equipment (booms, absorbent materials etc.)


  • Accident control, prevention and mitigation (cont.) description

    • Information expected on :

      • Basic parameters and standards for design

      • Safety equipment main characteristics (fire-fight water supplies locations/volumes, fire-fight pumps capacity, fire-fight network etc.)

      • Efficiency of safety measures (e.g. coverage of areas with hydrants/monitors and fire houses)


  • Accident control, prevention and mitigation (cont.) description

    • Information expected on : (cont.)

      • Control and monitor of measures (testing, inspection frequency)

      • Training related to safety measures

    • Information not to be providedwhen not contributing to report andbeing available else where, e.g. hydraulic calculations of pressure drop in fire-fight network (available anyway in fire-protection study)


  • A descriptionccident control, prevention and mitigation, Seveso III Directive Annex II

    • para.5.b : “organisation of alert and intervention”

    • Directly related with internal emergence plan :

      • Alert equipment and organisation

      • Emergency response team organisation and actions


  • A descriptionccident control, prevention and mitigation, Seveso III Directive Annex II (cont.)

    • para.5.c : “description of mobilisable resources, internal or external”

      • mobilisable resources : not available immediately

      • internal resources : within establishment e.g. masks or fire-fighting foam inventory stored in warehouse


  • A descriptionccident control, prevention and mitigation, Seveso III Directive Annex II (cont.)

    • para.5.c : (cont.)

      • External resources, e.g. collaborating installations providing, either additional emergency responders or emergency response equipment

      • Not to be confused with resources provided by Authorities during activation of External Emergency Plan


  • Risk Assessment Management description

    • Risk assessment should be applied throughout the whole lifecycle of an establishment

      • Conceptual design

      • Basic/Detailed design

      • Operation, maintenance, inspection

      • Revamps

    • Risk assessment should not be a static action due to submission of Safety Report, but a continuous process


  • Risk Assessment and Safety Management description

    • Risk assessment is a core element in Safety Management System (Seveso III Directive Annex III), as involved in:

      • identification and evaluation of major hazards

      • operational control

      • management of change


  • Deterministic approach in EU description(Cyprus, Germany, Greece, Spain etc.)

    • Analysis based only to consequence extents (safety zones defined by consequence end-points set by Authorities), no probabilities of accidents used

    • Simpler to implement

    • Smaller set of scenarios required



  • Deterministic approach descriptionin EU(cont.)

    • More conservative (all accidents are treated as equivalent), worst case scenarios included

    • Usually3 Safety Zonesset in-line with Zones for emergency planning

    • Inherently, safety measures not taken into account in general, no motivation for high performance safety measures


  • Deterministic approach in EU description(cont.)

    • Acceptance criteria set based on vulnerable objects presence in Zones *, Cyprus example :

      *Zones almost identical to Greek zones


  • Essential information expected for Consequence Analysis in Deterministic Approach

    • Description of models used, including :

      • assumptions on model parameters (e.g. atmospheric stability classes, confinement degree, exposure time) and support on assumptions validity

    • Consequence end-points and harm/damage relation (zone definition, toxicity data/probit functions)


  • Essential information expected for Consequence Analysis in Deterministic Approach (cont.)

    • Consequence analysis results on :

      • Release characteristics (rate, duration, mass)

      • Top event main characteristics (e.g. BLEVE diameter/duration)

      • Effects vs distance tables/graphs, Zone maps

      • Vulnerable object review (if required)

    • Risk acceptance results (risk matrix)


  • Deterministic Approach Deterministic Approach (cont.)BLEVE results example (table)

  • Thermal radiation level definedby Authorities for each Zone to be reported

  • Similar standard Zones defined for overpressure, toxics


  • Deterministic Approach Deterministic Approach (cont.)BLEVE results example (table) (cont.)

    • Usually 3 zones defined + Domino Zone

    • Standardisation in results presentation expected

    • Clarity to requirementsfor operators

    • Common approach : Zones definition related also to Emergency Planning purposes




  • Probabilistic approach in EU (UK, Ireland, Netherlands, Belgium-Flanders etc.)

    • Analysis based on determination of probability of a specific level of harm

    • Acceptancelimits usually set for Individual Risk

    • Societal Riskusually used as target/guide (not limit) value

    • Usually adopted in countries with high experienced institutions (HSE in UK, TNO/RIVM in Netherlands), providing extensive support/guidance to operators


  • Probabilistic approach in EU Belgium-Flanders etc.)(cont.)

    • Strong dependency on quality of datasets (e.g. event/failure probabilities database)

    • Usually requires large set of scenariosor screening method

    • Specialized software required for efficient implementation

    • Hard for risk communication to the public

    • Safety measures performance could be incorporated,remuneration/motivation for high performance safety measures



  • Essential information expected for Consequence Analysis in Probabilistic Approach

    • Methodology applied

    • Description of datasets for probabilities of :

      • initial release (e.g. failure of piping containing flammable gas),

      • intermediate event evolution (e.g. ignition of flammable cloud)

    • Harm/Damage relation with accident effects (e.g. probit functions for thermal radiation etc.)


  • Essential information expected for Consequence Analysis in ProbabilisticApproach (cont.)

    • Description of models used (as in deterministic approach)

    • Consequence analysis results on :

      • Release and top event characteristics (as in deterministic approach)

      • Effects vs distance tables/graphs (at least for predefined effect levels used in Emergency Planning)



  • Hybrid approach in EU (France, Italy etc.) Probabilistic Approach (cont.)

    • Probability band use, results not so strongly related to probability value quality

    • Sufficient support to operators is provided (e.g. Italy, France case) for endpoints, probit functions

    • Consequence endpoints set in Guidance documents or in legislation of Member States


  • Hybrid approach in EU Probabilistic Approach (cont.)(cont.)

    • Acceptance criteria defined by Risk Matrix using also severity (number/type of affected population)

    • Closer to Rulebook approach





  • Hybrid approach in EU Probabilistic Approach (cont.)(cont.)

    • France case (risk acceptance matrix for permits)


  • Essential information expected for Consequence Analysis in Hybrid Approach

    • Methodology applied

    • Description of datasets for probabilities (as in probabilistic approach)

    • Consequence end-points and harm/damage relation (zone definition, toxicity data/probit functions)

    • Description of models used (as in deterministic approach)


  • Essential information expected for Consequence Analysis in HybridApproach (cont.)

    • Consequence analysis results on :

      • Release and top event characteristics (as in deterministic approach)

      • Probability class results

      • Effects vs distance tables/graphs (at least for predefined effect levels requested)

      • Effect maps (for Emergency Planning)

      • Review of accidents severity

      • Risk Matrix results


  • Essential information expected for HybridDomino effects in all approaches

    • Damage levels required for Domino effects

    • Secondary accidents expected due to initial accident (internal primary accident, or known external accident)

    • Comment for accident escalation

    • Review if all secondary accidents had been included in risk assessment in the first place


  • Comparison of risk assessment approaches in EU Hybrid

    • No unique methodology in determination of risk values

    • No uniqueperception of risk, even for same category of approaches

      • probabilistic approach examples :

        • Netherlands : only “vulnerable” objects taken into account (hospitals, retirement homes, schools, non-scattered houses etc) in limit values

        • UK : workers and general public


  • Comparison of risk assessment approaches in EU (cont.) Hybrid

    • Diversity in risk limit values used, even for same approach (lower diversity in deterministic)

      • Probabilistic approach examples annual fatality individual risk limit value :

        • Netherlands : 10-6

        • Belgium (Flanders) : 10-5 fence, 10-6 (some residents), 10-7 (vulnerable objects)

        • UK : 10-3/10-4 workers/public (if As Low As Reasonably Practicable - ALARP), 10-6


  • Comparison of risk assessment approaches in EU (cont.) Hybrid

    • Diversity in definition of risk assessment elements, even for same approach

      • Although inherent in probabilistic concept (as affecting accident frequency related to Loss of Containment), several protection measures (e.g. overfill systems) not taken into account in some countries (e.g. Netherlands) during probability calculation


  • Comparison of risk assessment approaches in EU (cont.) Hybrid

    • Diversity in risk assessment elements, even for same approach

      • Probabilistic approach :

        • UK : highly flexible risk assessment procedure

        • Netherlands : “locked” risk assessment procedure described in relevant guidance (BEVI manual), fixed scenario selection method (TNO sub-selection method), unique commercial software to be used (SAFETI)


  • Comparison of risk assessment approaches in EU (cont.) Hybrid

    • Differences in primary data for same approach from different sources (e.g. failure rates considered in UK and Netherlands, or probit function of toxics)

    • Diversityin risk assessment for permitting, Land Use Planning and Emergency Planning even within one country : UK,: although probabilistic approach, for LPGs land use planning, deterministic results used (BLEVE consequences) 1800 TDU, 1000 TDU, 500 TDU


  • Open issues to be solved in each Member State Hybrid

    • Perception of risk (quantitative/qualitative, individual, societal)

    • Risk assessment methodologies to be applied

    • Scenarios selection

    • Effects severity (lethal, type/levels of injury)

    • Safety measures evaluation and link with risk

    • Risk acceptance criteria definition and application

    • Environmental Risk


  • Literature Hybrid

    • Guidance on the Preparation of a Safety Report to Meet the Requirements of Seveso Directive 1996/82/EC as Ammended by Directive 2003/105/EC (Seveso II), Major Hazard Accident Bureau, EU 2005.

    • JRC, Implementing Art.12 of the Seveso II Directive: Overview of Roadmaps for Land-Use Planning In Selected Member States, 2008.

    • CCPS Guidelines for Developing Quantitative Safety Risk Criteria, 2009.

    • Checklist System for Safety Reports, Instructions for Preparation and Inspection of a Safety Report (SR) in accordance with UNECE Convention on the Transboundary Effects of Industrial Accidents and the EU Directive 96/82/EC (SEVESO II) by a consistent Checklist system, Training Session for the Evaluation of Safety Reports 08 - 09 February 2010.


  • Literature (cont.) Hybrid

    • Guidelines for Preparation and Inspection of a Safety Report, UNECE convention on the transboundary effects of industrial accidents & the EU Directive 96/82/EC (SEVESO ll) by a consistent Checklist system, 2012.

    • Sectoral Checklist for Preparation and Inspection of a Safety Report, UNECE convention on the transboundary effects of industrial accidents & the EU Directive 96/82/EC (SEVESO ll) by a consistent Checklist system, 2012.

    • An international comparison of four quantitative risk assessment approaches, RIVM Report 620552001, 2011.

    • Safety Report Assessment Guides (SRAGs), Health and Safety Executive, UK.

    • RIVM, Reference Manual Bevi Risk Assessments, 2009.

    • Methodology for Evaluation of Safety Reports, Cyprus Ministry of Labour and Social Security, 2007 (in Greek).


  • Literature (cont.) Hybrid

    • National Guidelines for Inspection of Petroleum Products and Natural Gas Installations, University of Crete, 2004 (in Greek).

    • Hazardous Substances Council (AGS), Risk calculations by prescription: rituals for granting permits and land-use planning, 2010.

    • Clive Nussey, Failure frequencies for major failures of high pressure storage vessels at COMAH sites: A comparison of data used by HSE and the Netherlands, HSE, December 2006.


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