Risk-Informed Decision-Making: Basic Concepts Presentation to the - - PowerPoint PPT Presentation

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Risk-Informed Decision-Making: Basic Concepts

Presentation to the State Energy Risk Assessment Workshop

April 28-29, 2015

Presented by Steve Unwin, Ph.D.

Pacific Northwest National Laboratory

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PNNL-SA-108973

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Outline

Risk Decisions Risk Models Risk Management Risk Perception Risk Guidance First Steps

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Risk-Informed Decision-Making

Decisions that take into account:

Uncertain future events The impacts of those events The likelihoods of those events

Structuring data, judgment, and system logic in a coherent framework for decision-making Risk-Informed versus Risk-Based decisions

The reality of accounting for risk

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Modeling Risk

Hazard

condition that poses threat: presence of flammables or toxics, natural phenomena, potential for market upsets, threat of malevolent acts, presence of physical energies, ...

Scenario

specific hypothetical sequence of events that would result in adverse consequences

Risk

a combination of the adverse consequences and likelihoods of a scenario set

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Risk Models – What varies between them?

Scope

natural phenomena? terrorism? human factors? system boundaries? impact region of concern? ...

Depth

model resolution: e.g., industries vs. facilities vs. systems vs. components (how far into the weeds?)

Precision

full quantitative vs. order of magnitude vs. qualitative

Risk types

safety, environmental, production/outage, business, schedule, budget, public perception

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5/1/2015

Risk Type: Business – Risk (probability- weighted production loss) associated with forced outage of refinery units

200,000 400,000 600,000 800,000 1,000,000 1,200,000 1,400,000 CRUDE BLENDING CRUDE UNIT VACUUM DISTILLATION DELAYED COKING NAPHTHA HYDROTREATING DISTILLATE HYDROTREATING GAS OIL HYDROTREATING REFORMING FLUIDIC CAT CRACKING OLEFIN TREATING ALKYLATION VAPOR RECOVERY/GAS TREAT SOUR WATER STRIPPING SULFUR RECOVERY HYDROGEN PLANT

Downtime $ risk per quarter

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5/1/2015

Risk Type: Safety & Health – Frequency vs. number of individuals exceeding ERPG2 exposure due to presence

• f a selective catalytic reduction unit at a fossil plant

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Broadly Risk-Oriented: Representation of bulk power system interruption

NERC, 2010

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Structure of a Risk Model

Models

Mechanistic models

natural phenomena engineered system behavior

Logic models (event trees, fault trees, networks)

logical relationships between events

Evidence/likelihood models probabilistic

• ther

Consequence models health, exposure, financial, reputation, ...

Input

Hard data/statistical models Informed judgment

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Example: Event tree that models fire risk in a research facility – Systematically defines scenarios

Ignition Failure to immediately extinguish Ignition was in a Cluster area Failure to prevent propagation beyond room/cluster END STATE Ignition occurs Personnel unable to extinguish immediately or no extinguishers present No fire suppression system (sprinkler) in place, failure to actuate locally, or system ineffective High combustibles / flammables load in adjacent rooms No fire suppression (sprinkler) system in place, or failure to actuate globally, or system ineffective Failure of other fire isolation system (fire wall) Failure of emergency response

• rganization to

respond effectively P1: Annual Frequency P2: Probability (Yes) P3: Probability (Yes) P4: Indicator P5: Probability (Yes) P6: Probability (Yes) P7: Probability (Yes) P8: Probability (Yes) Yes Yes Yes Yes Yes Yes Yes

• 1. Building Cluster Damage

No

• 2. Local Cluster Damage

No

• 3. Local Cluster Damage

No

• 4. Local Cluster Damage

No

• 5. Local Cluster Damage

No Yes Yes Yes Yes

• 6. Building Cluster Damage

No OK No OK No OK No OK No Yes

• 7. Local Water Damage

No OK No OK

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Risk Management

Doing what needs to be done to continually and economically reduce risks. Once we know where the greatest risks lie, effectively manage them.

Where can resources be most effectively spent to reduce risk? Where might expenditures be reduced without significantly affecting risk?

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The Elements of Risk Management

Analysis Evaluation Control Communication Research Monitoring

Determining risks and uncertainties

Identifying risk and

uncertainty drivers. Assessing risk and uncertainty-reduction

• ptions

Reducing the uncertainties Reducing and controlling the risks Communicating risks and their management to stakeholders Ongoing confirmation/revision of assumptions about risk

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Risk-Informed Decision Portfolio

Risk tolerance criteria/goals, limits/objectives

numerical risk acceptance levels

Risk-based prioritization/allocation

risk importance metrics

Cost/benefit analysis ALARP

as low as reasonably practicable risk-based cost-benefit analysis

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Risk objectives and limits. Risk acceptance criteria for public radiation exposure

1.0E-06 1.0E-05 1.0E-04 1.0E-03 1.0E-02 1.0E-01 1.0E+00 1.0E+01 1.0E-01 1.0E+00 1.0E+01 1.0E+02 1.0E+03 1.0E+04 Annual Exceedence Frequency Maximum Individual Public Dose (mSv)

UK Health and Safety Executive Dose Tolerance Basic safety limit Basic safety objective

Targeted risk level Greatest tolerable risk level

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Risk-ranking for explosion damage in chemical process facility

STRUCTURE RANK

6 Fermentation Building 2.8 3 Process 95 Building 2.9 2 Control Room A 2.9 5 Extraction Building 3.0 4 Laboratory Area 3.1 7 Maintenance Building 3.3 10 Guard Shack 3.4 9 Stores 6.2 8 Warehouse 6.9 1 Administration Offices X

SOURCE RANK

Fermentation Area VCE 2.3 Process 95 PVE 2.9 Extraction Area PVE 3.3 Process 95 VCE 3.8 Extraction Area VCE 6.2 Main Storage PVE 6.2 Tank Farm B BLEVE 6.4 Main Storage BLEVE 7.1 Tank Farm B PVE 8.0

Vulnerable Structures Explosion Sources High rank = high protection priority High rank = high prevention priority

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Cost-Benefit Criteria: Risk reduction / cost tradeoff

USNRC:

US$ 2,000/person-rem (radiological dose) averted

UK HSE:

UK£ 0.75 M per fatality averted

Range inferred from a variety of organizations (1990s):

$20K - $100M per fatality averted

Cost Risk- Reduction Unwarranted expenditure Cost-beneficial expenditure

Cost-benefit acceptance threshold

Assessing a risk- reduction

• ption:

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ALARP: As Low (A Risk) As Reasonably Practicable

Reduce Risk Regardless of Cost Follow Good Practice Consider Cost

• f Risk-

Reduction

De Minimis Risk

Risk Intolerable Tolerable if ALARP Risk Tolerable

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Risk Perception

Perceived versus calculated Factors driving risk perception

Personal controllability of exposure Dreadedness of potential consequences “Visibility” of exposure Fairness of risk and benefit distribution

Peter Sandman’s Equation

Risk = Hazard + Outrage

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Risk Perception Factors

DNA Technology SST Electric Fields DES Nitrogen Fertilizers Radioactive Waste Cadmium Usage Mirex Trichloroethylene 2,4,5-T Nuclear Reactor Accidents Uranium Mining Pesticides Nuclear Weapons Fallout PCBs Asbestos Insulation Satellite Crashes Mercury DDT Fossil Fuels Coal Burning (Pollution) Nerve Gas Accidents D-CON LNG Storage & Transport Auto Exhaust (CO) Coal Mining (Disease) Large Dams SkyScraper Fires Nuclear Weapons (War) Coal Mining Accidents General Aviation Sport Parachutes Underwater Construction High Construction Railroad Collisions Commercial Aviation Alcohol Accidents Auto Racing Auto Accidents Handguns Dynamite Fireworks Bridges Motorcycles Bicycles Electric Wir & Appl (Shock) Smoking Recreational Boating Downhill Skiing Electric Wir & Appl (Fires) Home Swimming Pools Elevators Chainsaws Alcohol Tractors Trampolines Snowmobiles Power Mowers Skateboards Smoking (Disease) Caffeine Aspirin Vaccines Lead Paint Rubber Mfg. Auto Lead Antibiotics Darvon IUD Valium Diagnostic X-Rays Oral Contraceptives Polyvinyl Chloride Coal Tar Hairdyes Hexachlorophene Water Chlorination Saccharin Water Fluoridation Nitrates Microwave Ovens Laetrile

Factor 2 Unknown risk Factor 1 Dread risk

Uncontrollable Dread Global Catastrophic Consequences Fatal Not Equitable Catastrophic High Risk to Future Generations Not Easily Reduced Risk Increasing Involuntary Not Observable Unknown to Those Exposed Effect Delayed New Risk Risk Unknown to Science

From:

Slovic, P. (1987). Perception

• f risk. Science, 236, 280-

285.

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Risk Standards / Methodology Guides / Risk Acceptance Criteria / Review Guides

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Risk reading: A few starting points -

Quantifying and Controlling Catastrophic Risks, by B. John Garrick (Academic Press, 2008) U.S. Nuclear Regulatory Commission, A Proposed Risk Management Regulatory Framework, NUREG-2150, 2012 Guidelines for Chemical Process Quantitative Risk Analysis (American Institute of Chemical Engineers, 2nd Ed., 1999) NASA, Risk-Informed Decision Making Handbook, NASA/SP-2010-576, 2010

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First Steps

Objectives/Drivers?

strategy selection, design support, optimizing operations, public communications, ...

Hazard space?

incidents/accidents natural phenomena malevolent acts market events etc.

Risk space?

financial environmental production safety security public perception