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DNV GL © 2015 14 June 2017 SAFER, SMARTER, GREENERDNV GL © 2015
14 June 2017
Introduction to Quantitative Risk Assessment
1
Webinar June 2017
DNV GL © 2015 14 June 2017
Kenny ShabaPhast and Safeti Product Manager
with extensive experience in
Technical Safety projects
(especially QRA) for both onshore
and offshore assets
2
Mark HunterChartered Engineer
in DNV GL’s Advisory business
10 years’ experience of safety related studies in the oil & gas
sector
SpeakersSpeakers
DNV GL © 2015 14 June 2017
For further inquiry, demo, test, training or quote,
please contact us:
3
Please use the chat window on Go to Webinar control panel
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NotesNotes
DNV GL © 2015 14 June 20174
Agenda
Drivers for QRA why QRA?01
03
05
02
04
06
Pros/Cons of QRA
Conclusion
What is QRA?
Challenges that QRA can help address/Applications of QRA
Doing a QRA –Practical considerations, best practices, pitfalls
Agenda
DNV GL © 2015 14 June 2017
What is QRA?
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What is Risk?
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Commonly used definition…
The LIKELIHOOD and consequence of a specifiedundesired event occurring within
a specified period or under specified circumstances
R = f(L,C)
DNV GL © 2015 14 June 2017
What is Quantitative Risk Assessment?
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is a risk assessment methodology that allows
for numerical estimates of the level of risk
associated with a certain activity or series of activities to
be estimated and then assessed
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What Can Go Wrong?Hazard Identification
How Big?Consequence Analysis
How Often?Frequency Analysis
So What?Risk Assessment
What Do I Do?Risk Mitigation
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What is Quantitative Risk Assessment?
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Typical QRA Outputs
Individual Risk Societal (Group) Risk
– “Relationship between frequency and the number of people
suffering from a specified level of
harm from the realisation of
specific hazards”
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1 in 1,000
1 in 10,000
1 in 1,000,000
1 in 100,000
1 in 10,000,000
UNACCEPTABLE RISK
BROADLYACCEPTABLE
RISK
Riskiest Industry
Traffic Accident
(driving 10h per week)
SafestIndustry
Struckby lightning
Solo rockclimbing
(5 hr per week)
HeartDisease
Smoking(10 cigarettes
per day)
Accidentat home
DNV GL © 2015 14 June 2017
Typical QRA Outputs – Individual Risk
10
0.00 0.20 0.40
km
LSIR
Location Specific Individual Risk
IRPA
Individual Risk Per Annum
“1 in 10 000/Yr” or “10-4/Yr”
“1 in 100 000/Yr” or “10-5/Yr”
“1 in 1 000 000/Yr” or “10-6/Yr”
“1 in 10 000 000/Yr” or “10-7/Yr”
10-8/Yr
10-9/Yr
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Individual Risk – ALARP Principle
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NEGLIGIBLE RISK
Unacceptable region
The ALARP or Tolerabilityregion(Risk is undertaken only ifa benefit is desired)
Broadly acceptable region(No need for detailed working todemonstrate ALARP)
Risk cannot be justifiedsave in extraordinary
circumstances
Tolerable only if risk reduction isimpracticable or if the cost is grosslydisproportionate to the improvement
gainedTolerable if cost of reduction would
exceed the improvement
Necessary to maintain assurancethat risk remains at this level
LOW RISK
HIGH RISK
MaximumTolerableCriterion
Desirable Target
ALARP – As Low as Reasonably Practicable
DNV GL © 2015 14 June 2017
Individual Risk Criteria – Global Examples
Country 2 Bands 3 Bands
UK: Safety Cases/Reports
UK: Land Use Planning
Netherlands
Belgium: Flanders
Hong Kong
Brazil (3 states)
Singapore
Malaysia
Australia: Western Australia
Australia: New South Wales
Australia: Queensland
Australia: Victoria
Canada
France
Switzerland
USA: Federal Agencies
USA: Santa Barbara County, CA
USA: New Jersey
IMO
Abu Dhabi
3 bands
2 bands
Intolerable
Tolerable
Intolerable
ALARP
ALARP
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Typical QRA Outputs – Societal (Group) Risk
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FN Curves
Frequency/Number of fatalities
PLL
Potential Loss of Life
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Sample Societal Risk Criteria (Upper Limit)
UK HSE
RdJ & RGdSVictoria
Hong KongSão P & WA existingFlanders
Santa BarbaraNetherlands & CHWA newNSW
1 100010010 10000
10-2
10-3
10-4
10-5
10-6
10-7
10-8
10-9
Fre
qu
en
cy (
/year)
of
N o
r m
ore
fata
liti
es
Number of fatalities, N
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Drivers for QRA
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Drivers for QRA
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NRC WASH-1400 Reactor Safety Study
?
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Drivers for QRA
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Decisionsupport tool
Core processsafety methodology
Key to Risk Regulation
Today, QRA is a …
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Challenges that QRA can help address? /Applications of QRA
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Examples of QRA Applications
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Equipment Design
Technology Option
Selection
Land Use Planning
Quantify the benefit of mitigation measures
Safety Case Development
Life Cycle Asset Risk Management
• Design• Construction• Operations • Decommissioning
Escalation Assessment
Layout Optimization• Site• Equipment
Insurance
Cost Benefit AnalysisDecision
Support
Operational Risk
Management
Compliance (Legal
Requirement)
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Example of Cost Benefit Analysis
Base
Risk
Cost
1 2 3 4
1 Cost a lotLittle reduction in risk
2 Cost a littleLittle reduction in risk
3 Cost is moderateModerate reduction in risk
4 Cost is relatively littleLarge reduction in risk
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Pros/Cons of QRA
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Pros of QRA
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Identify Risk Drivers
Enables risk (various)
to be quantified
Visual Depiction of
Risk
Understanding an
Engineered System
Offers an
objective/rational
approach to risk
assessment
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Strengths of QRA - Understanding an Engineered System
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“The key benefit of estimating risk lies in the achievement of detailed understanding
of the engineered system and the implications of various siting and technical
options”. (Royal Society, 1999)
Hazard
• Flammable material
• Toxic material
Environment
• Weather• Ignition• Explosion
sources
Receptor
• People
• Assets
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Strengths of QRA – Visual Depiction of Risk
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0.00 0.20 0.40
km
“1 in 10,000/Yr” or “10-4/Yr”
“1 in 100,000/Yr” or “10-5/Yr”
“1 in 1 000,000/Yr” or “10-6/Yr”
“1 in 10 000,000/Yr” or “10-7/Yr”
10-8/Yr
10-9/Yr
DNV GL © 2015 14 June 2017
Strengths of QRA – Identify Risk Drivers
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“The process of undertaking a QRA can lead to a better understanding of the important features contributing to risk and weaknesses in the systems as well as allowing a numerical estimate of the residual risk to be derived” (HSE, 1999)
Risk at Control RoomBreakdown by Scenario
Scenario 1 Scenario 2
Scenario 3 Scenario 4
Risk at Control RoomBreakdown by Hazard Type
Toxic Explosion Jet Fire
Pool Fire Flashfire Fireball
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Cons of QRA
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Uncertainty in the risk
estimates
Addressed by adopting a
conservative approach
Highly specialised
activity
Expertise e.g. DNV GL is
available
Susceptible to “GIGO” Expertise is key
Cost/time intensive
Addressed by software tools
such as Safeti reduce the
analytical burden approach
DNV GL © 2015 14 June 2017
Doing a QRA – Practical considerations, best practices, pitfalls
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QRA is akin to predicting the weather…
Goal is to predict the weather based on
available data, models
Accuracy is dependent on a range of
factors:
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Key Considerations for QRA
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Choice of Software application Competency of resources
Quality ManagementUncertainty
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Practicalities
Do I need a QRA?
– Is it appropriate for my site?
– How will I use the results?
– Regulatory requirements?
Information needed?
Can I do the QRA myself or do I need someone else to do it?
– Capabilities/competencies
– Software
– 3rd party assurance (may be regulatory requirement)
– Maybe mix both in-house and external
Documentation – the QRA should be well documented (all assumptions etc.)
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Software Applications for QRA
Many solutions exist, most are in-
house proprietary and Microsoft
Excel® based (i.e. spreadsheet
models)
Commercial quality QRA software is
available e.g. Safeti/Safeti Offshore for
on/offshore QRA respectively
– High quality, integrates codified best
practice and industry standards
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How to check a QRA Study/Report for quality etc.
Independent checks - verification
Validation versus comparable assets
Specifically, check:
– Main risk contributors – are they as expected and consistent with experience?
– Consistency of:
– Individual versus Societal risk
– FN Curve and PLL
– FN Curve and individual risks
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DNV GL © 2015 14 June 2017 Slide 33
The need to dig deeper: Hazards With Same PLL
1.0E-06
1.0E-05
1.0E-04
1.0E-03
1.0E-02
1.0E-01
1 10 100 1000
Number of Fatalities
Fre
qu
ency
of
Exc
eed
ance
FrequencyNo of
fatalitiesPLL
1 per 10 years 1 0.1
1 per 100 years 10 0.1
1 per 1000 years 100 0.1
1 per 10000 years 1000 0.1
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Conclusion
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Conclusions
What is QRA?
Why/ how is it done?
What is it used for?
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DNV GL © 2015 14 June 2017
Useful resources on QRA and Risk Analysis
American Institute of Chemical Engineers. Center for Chemical Process Safety,
2000. Guidelines for chemical process quantitative risk analysis (Vol. 1). Wiley-
AIChE.
CPR (1999) CPR18E “Purple book”. Sdu Uitgevers, Den Haag, 1999
HSE (1999) Reducing Risks, Protecting People
McQuaid, J (2007) “A Historical Perspective on the Tolerability of Risk” in “Bouder,
Frédéric, and David Slavin. The tolerability of risk: a new framework for risk
management. Earthscan, 2007”.
Royal Society (1992) Royal Society Study Group on Risk “Risk: analysis, perception and management” - report of a Royal Society Study Group. London:
Royal Society , 1992.)
OECD (2003) “OECD Guiding principles for Chemical Accident Prevention, Preparedness and Response”. OECD
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Q&A
37
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please contact us:
38
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