xxiliContents47714PresentationofRiskResultsfromQRAStudies47714.1RequirementsforRiskPresentation.47714.1.1RegulatoryRequirements.47814.1.2RiskResultPresentationandRiskAcceptanceCriteria.47814.1.3ProposedPresentationFormat47914.2PresentationofRiskAccordingtoApplicationArea.47914.2.1LifeCyclePhases.47914.2.2ALARPEvaluations47914.2.3RiskPresentationforDifferentUserGroups.14.2.4FrameworkforRiskPresentations48048014.3PresentationofOverallRisk48014.3.1MainResults...48114.3.2References for Risk Results.48214.4PresentationofRiskContributions.48214.4.1FARContributions.48514.4.2ContributionsforLeakFrequencies.48614.4.3FireandExplosionCharacteristics..48714.5Presentationof SignificantImprovements.14.6PresentationofSensitivityStudies48849014.7EvaluationofUncertainty49114.8PresentationFormatforEasyUnderstanding49315Use of Risk Analysis duringOperations Phase.49315.1StudyUpdating.49315.1.1Overview49415.1.2ScopeofUpdating49515.1.3FrequencyofUpdating.49515.2BORAAnalysisofOperationalImprovement.49515.2.1OverviewofCaseStudies49615.2.2ResultsfromSensitivityStudies49615.3Useof SensitivityStudiesforSafetySystemsImprovement.49715.3.1RiskManagementObjectives49815.3.2Casestudy:EffectofImprovedBlowdown50015.4CaseStudyCostBenefitAnalysis50115.4.1FieldData..50215.4.2Definition of RiskReducing Measure50215.4.3 Risk Reducing Potentials..50215.4.4OverallApproachtoComparisonofCostsandBenefits.50315.4.5ModellingofBenefits.50515.4.6 Modelling of Costs..50615.4.7Results.50615.4.8DiscussionandEvaluation.50715.4.9Conclusions15.5RiskIndicators50850815.5.1PFEERApproachtoRiskMonitoring51015.5.2Objectives.51115.5.3ProposedApproachtoSelectionofIndividual Indicators51615.5.4 Weights for Individual Indicators
Contents xxiii 14 Presentation of Risk Results from QRA Studies. 477 14.1 Requirements for Risk Presentation. 477 14.1.1 Regulatory Requirements . 477 14.1.2 Risk Result Presentation and Risk Acceptance Criteria . 478 14.1.3 Proposed Presentation Format . 478 14.2 Presentation of Risk According to Application Area. 479 14.2.1 Life Cycle Phases . 479 14.2.2 ALARP Evaluations . 479 14.2.3 Risk Presentation for Different User Groups. 479 14.2.4 Framework for Risk Presentations. 480 14.3 Presentation of Overall Risk . 480 14.3.1 Main Results. 480 14.3.2 References for Risk Results. 481 14.4 Presentation of Risk Contributions . 482 14.4.1 FAR Contributions . 482 14.4.2 Contributions for Leak Frequencies . 485 14.4.3 Fire and Explosion Characteristics . 486 14.5 Presentation of Significant Improvements. 487 14.6 Presentation of Sensitivity Studies. 488 14.7 Evaluation of Uncertainty. 490 14.8 Presentation Format for Easy Understanding . 491 15 Use of Risk Analysis during Operations Phase . 493 15.1 Study Updating . 493 15.1.1 Overview . 493 15.1.2 Scope of Updating . 494 15.1.3 Frequency of Updating . 495 15.2 BORA Analysis of Operational Improvement. 495 15.2.1 Overview of Case Studies. 495 15.2.2 Results from Sensitivity Studies. 496 15.3 Use of Sensitivity Studies for Safety Systems Improvement. 496 15.3.1 Risk Management Objectives. 497 15.3.2 Case study: Effect of Improved Blowdown. 498 15.4 Case Study Cost Benefit Analysis . 500 15.4.1 Field Data . 501 15.4.2 Definition of Risk Reducing Measure . 502 15.4.3 Risk Reducing Potentials. 502 15.4.4 Overall Approach to Comparison of Costs and Benefits. 502 15.4.5 Modelling of Benefits. 503 15.4.6 Modelling of Costs . 505 15.4.7 Results . 506 15.4.8 Discussion and Evaluation. 506 15.4.9 Conclusions . 507 15.5 Risk Indicators . 508 15.5.1 ‘PFEER’ Approach to Risk Monitoring . 508 15.5.2 Objectives. 510 15.5.3 Proposed Approach to Selection of Individual Indicators . 511 15.5.4 Weights for Individual Indicators. 516
xxiv Contents51715.6AnalysisofMaintenanceActivities...51715.7OverallAnalysisofModifications..51715.7.1Overview51815.7.2ModificationRiskinaLifeCyclePerspective.52015.8Tie-inofNewFacilities.523AppendixA:Overview of Software523A.1 Introduction...524A.2ElectronicContacts526A.3QuantitativeRiskAnalysisSoftware526A.3.1ASAPRA.3.2COSAC527528A.3.3 CRA Tool528A.3.4NEPTUNE529A.3.5PLATO529A.3.6 RiskSpectrumA.3.7RISK531A.3.8 SAFETI.531532A.4QRATools for ScenarioandProbabilityAnalysis532A.4.1BlowFAM*A.4.2COAST*532533A.4.3COLLIDE*533A.4.4DatabaseManager534A.4.5EgressA.4.6LEAK*534A.4.7R-DATPlus535535A.4.8CARA-FaultTree536A.5QRAToolsforConsequenceAnalysis536A.5.1AutoReaGasA.5.2 Firex536A.5.3FLACS*537A.5.4KAMELEONFireEx-KFX.539.540A.5.5Mona540A.5.60lga540A.5.7PHAST541A.6QualitativeRiskAssessmentSoftwareA.6.1PHA-Pro*.541A.6.2PHAROS541542A.6.3Kyrass*.542A.6.4Sabaton543A.7Reporting andAnalysis of Incidents and Accidents543A.7.1ProSafe...543A.8RiskManagementSoftware..543A.8.1Hazard LogDatabaseManagementTool.544A.8.2PrismA.8.3 Riskplot I1.544545A.8.4ORBITOffshore
xxiv Contents 15.6 Analysis of Maintenance Activities . 517 15.7 Overall Analysis of Modifications. 517 15.7.1 Overview . 517 15.7.2 Modification Risk in a Life Cycle Perspective. 518 15.8 Tie-in of New Facilities . 520 Appendix A: Overview of Software . 523 A.1 Introduction. 523 A.2 Electronic Contacts . 524 A.3 Quantitative Risk Analysis Software . 526 A.3.1 ASAP® . 526 A.3.2 COSAC®. 527 A.3.3 CRA Tool® . 528 A.3.4 NEPTUNE® . 528 A.3.5 PLATO . 529 A.3.6 RiskSpectrum®. 529 A.3.7 RISK® . 531 A.3.8 SAFETI®. 531 A.4 QRA Tools for Scenario and Probability Analysis . 532 A.4.1 BlowFAM®. 532 A.4.2 COAST® . 532 A.4.3 COLLIDE® . 533 A.4.4 Database Manager® . 533 A.4.5 Egress® . 534 A.4.6 LEAK® . 534 A.4.7 R-DAT Plus® . 535 A.4.8 CARA-Fault Tree® . 535 A.5 QRA Tools for Consequence Analysis . 536 A.5.1 AutoReaGas®. 536 A.5.2 Firex®. 536 A.5.3 FLACS®. 537 A.5.4 KAMELEON FireEx-KFX®. 539 A.5.5 Mona®. 540 A.5.6 Olga® . 540 A.5.7 PHAST®. 540 A.6 Qualitative Risk Assessment Software . 541 A.6.1 PHA-Pro® . 541 A.6.2 PHAROS® . 541 A.6.3 Kyrass® . 542 A.6.4 Sabaton® . 542 A.7 Reporting and Analysis of Incidents and Accidents . 543 A.7.1 ProSafe®. 543 A.8 Risk Management Software. 543 A.8.1 Hazard Log Database Management® Tool . 543 A.8.2 Prism®. 544 A.8.3 Riskplot II® . 544 A.8.4 ORBIT Offshore® . 545
ContentsXXVA.8.5 BowTieXP"IADC Edition and Black BowTieXp.545A.8.6THESIS.546..549GlossaryAbbreviations....555References..559.573Index
Contents xxv A.8.5 BowTieXP® IADC Edition and Black BowTieXP® . 545 A.8.6 THESIS. 546 Glossary. 549 Abbreviations. 555 References. 559 Index . 573
1Introduction1.1 About'QRA'"QRA'is used as theabbreviation for“Quantified RiskAssessment'or“Quantita-tive Risk Analysis'.The context usually has to be considered in order to determinewhichofthesetwotermsisapplicable.Riskassessmentinvolves(seeAbbre-viations, Page555)riskanalysisas well as an evaluation of theresults.QRA'isone of the terms used for a type of risk assessment frequently applied to offshoreoperations,Thistechnique is alsoreferred toas:QuantitativeRiskAssessment(QRA)..ProbabilisticRiskAssessment(PRA).ProbabilisticSafetyAssessment(PSA)Concept Safety Evaluation (CSE).Total Risk Analysis (TRA), etc..In spite of more than two decades of use and development, no convergencetowardsauniversallyacceptedtermhasbeenseen.QRAandTRAarethemostcommonly used abbreviations.The nuclear industry,with its origins in the USA,particularlyfavours thetermsProbabilisticRiskAssessmentorProbabilistic SafetyAssessment.Concept Safety Evaluation (CSE) has been used since 1981 in Norway andappears tohavearisen as aresult of risk assessmentof newconcepts.TotalRiskAnalysis (TRA),also originated in Norway as a term implying essentially adetailed fatality risk analysis.It may be argued that all of these terms have virtually the same meaning.Thisbook will concentrateon theterm“QRA'as an abbreviation for'QuantitativeRiskAnalysis'.An alternative would be to useQRA'as an abbreviation for“Quanti-tativeRisk Assessment',the differencebetween these two expressions being thatthe latter includes evaluation of risk, in addition to the analysis of risk.Use of QRA studies in the offshore industry dates backto the second half ofthe1970s.Afewpioneer projects wereconducted at thattime, mainlyfor researchand
1 Introduction 1.1 About ’QRA’ ‘QRA’ is used as the abbreviation for ‘Quantified Risk Assessment’ or ‘Quantitative Risk Analysis’. The context usually has to be considered in order to determine which of these two terms is applicable. Risk assessment involves (see Abbreviations, Page 555) risk analysis as well as an evaluation of the results. ‘QRA’ is one of the terms used for a type of risk assessment frequently applied to offshore operations. This technique is also referred to as: y Quantitative Risk Assessment (QRA) y Probabilistic Risk Assessment (PRA) y Probabilistic Safety Assessment (PSA) y Concept Safety Evaluation (CSE) y Total Risk Analysis (TRA), etc. In spite of more than two decades of use and development, no convergence towards a universally accepted term has been seen. QRA and TRA are the most commonly used abbreviations. The nuclear industry, with its origins in the USA, particularly favours the terms Probabilistic Risk Assessment or Probabilistic Safety Assessment. Concept Safety Evaluation (CSE) has been used since 1981 in Norway and appears to have arisen as a result of risk assessment of new concepts. Total Risk Analysis (TRA), also originated in Norway as a term implying essentially a detailed fatality risk analysis. It may be argued that all of these terms have virtually the same meaning. This book will concentrate on the term ‘QRA’ as an abbreviation for ‘Quantitative Risk Analysis’. An alternative would be to use ‘QRA’ as an abbreviation for ‘Quantitative Risk Assessment’, the difference between these two expressions being that the latter includes evaluation of risk, in addition to the analysis of risk. Use of QRA studies in the offshore industry dates back to the second half of the 1970s. A few pioneer projects were conducted at that time, mainly for research and
2OffshoreRiskAssessmentdevelopmentpurposes,in orderto investigate whether analysis methodologies anddataof sufficientsophisticationandrobustnesswereavailableThe methodologies and data were mainly adaptations of what had been used forsomefewyears within thenuclear powergeneration industry,mostnotablyWASH1400(NRC,1975)whichhadbeendeveloped3-4yearsearlierThenextstepinthedevelopmentof QRAcamein1981whentheNorwegianPetroleumDirectorateissued guidelinesforsafety evaluation of platform concep-tualdesign(NPD,1980).TheseregulationsrequiredQRAbecarriedoutforallnew offshore installations in the conceptual design phase.The regulations contai-nedacut-offcriterionof1o-perplatformyearasthefrequencylimitforaccidentsthat needed to be considered in order to define design basis accidents,the so calledDesignAccidentalEvents.When the design basis accidents had been selected and protective measuresimplemented, the residual risk had to beassessed.These residual levels were to becompared to the cut-off limit as stated above.Figure 1.1 shows a typical set ofresultsfor a floatingproduction concept wheretheannual frequencyfor events thatimpairthedifferentsafetyfunctions isgiven.1,0E-031,0E-04 HC Fire&ExplosionCollisionStructural failureOtherfire1,0E-051,0E-06ShelterHullEscapeEvacuationEscalationwaysareastructureMainSafetyFunctionsFigure1.1.Annual frequencies for Residual Accidental EventsFor manyyears,Norway was the only country using QRAs systematically.Theoffshore industry and authorities in the UK persistentlydeclared that such studieswerenottherightwayto improvesafetyThe next significant step in this development was the official inquiry,led byLord Cullen in the UK,following the severe accidenton thePiper Alpha platformin1988.LordCulleninhisreport(LordCullen.1990),recommendedthatORAsshould be introduced into UK legislation in much the same way as in Norwaynearly10yearspreviouslyIn1991theNorwegianPetroleumDirectoratereplaced the1981guidelinesforrisk assessmentbyRegulationsforRiskAnalysis(NPD,1990)which considerablyextendedthescopeofthesestudiesIn 1992the SafetyCaseRegulations came into force in the UK(HSE,1992)and since then the offshore industry in the UK has been required to perform risk
2 Offshore Risk Assessment development purposes, in order to investigate whether analysis methodologies and data of sufficient sophistication and robustness were available. The methodologies and data were mainly adaptations of what had been used for some few years within the nuclear power generation industry, most notably WASH 1400 (NRC, 1975) which had been developed 3–4 years earlier. The next step in the development of QRA came in 1981 when the Norwegian Petroleum Directorate issued guidelines for safety evaluation of platform conceptual design (NPD, 1980). These regulations required QRA be carried out for all new offshore installations in the conceptual design phase. The regulations contained a cut-off criterion of 10-4 per platform year as the frequency limit for accidents that needed to be considered in order to define design basis accidents, the so called Design Accidental Events. When the design basis accidents had been selected and protective measures implemented, the residual risk had to be assessed. These residual levels were to be compared to the cut-off limit as stated above. Figure 1.1 shows a typical set of results for a floating production concept where the annual frequency for events that impair the different safety functions is given. 1,0E-06 1,0E-05 1,0E-04 1,0E-03 Escape ways Shelter area Evacuation Hull structure Escalation Main Safety Functions Impairment frequency (/yr) HC Fire&Explosion Collision Structural failure Other fire Figure 1.1. Annual frequencies for Residual Accidental Events For many years, Norway was the only country using QRAs systematically. The offshore industry and authorities in the UK persistently declared that such studies were not the right way to improve safety. The next significant step in this development was the official inquiry, led by Lord Cullen in the UK, following the severe accident on the Piper Alpha platform in 1988. Lord Cullen in his report (Lord Cullen, 1990), recommended that QRAs should be introduced into UK legislation in much the same way as in Norway nearly 10 years previously. In 1991 the Norwegian Petroleum Directorate replaced the 1981 guidelines for risk assessment by Regulations for Risk Analysis (NPD, 1990) which considerably extended the scope of these studies. In 1992 the Safety Case Regulations came into force in the UK (HSE, 1992), and since then the offshore industry in the UK has been required to perform risk