Engineering Risk Assessments and Risk Communication

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Engineering Risk Assessments and Risk
Communication
Sarah Arulanandam, Hazard and Risk Group RWDI
West Inc.
DISCLOSURE OF MATERIAL ENVIRONMENTAL EXPOSURES
What should investors expect? January 20, 2005
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Definitions of Risk

• Risk frequency x consequence
• Frequency accidental releases, upset conditions
• Consequences short-term, acute
• Risk exposure x effect
• Exposure low-level, continuous emissions
• Effect long-term chronic
• Risk frequency x consequence x outrage
• Outrage stakeholders, media, public, government
• Risk attractiveness of target x consequence
• Attractiveness likelihood of attack
• Risk ???

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RISK BASED DECISIONS

• TECHNOLOGY SELECTION
• Design Construction Standards
• Control Options
• Accident, Mitigation Recovery Options

• RISK ASSESSMENT
• Public Involvement
• Guidelines Standards
• Risk Utility
• Risk Acceptability
• Risk Communication

RISK MANAGEMENT

• HAZARD ANALYSIS
• Hazard Identification
• Source Term Modelling
• Dispersion Modelling Forecasting
• Receptor Response Modelling

• RISK ANALYSIS
• Employee and Worker Safety
• Public Safety
• Environmental
• Financial

• FREQUENCY ANALYSIS
• Historical Accident Incident Data
• Predictive Failure Models
• Event Tree Analysis
• Fault Tree Analysis

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Steps Involved in Hazard and Risk Management

• Identify the hazards
• Define the system and characterize the source
• Conduct dispersion modelling
• Estimate the consequences
• Compare hazard results to accepted public health
  and safety criteria
• Review the options for managing the hazards
• Examine failure frequencies and event
  probabilities
• Estimate the risk
• Compare risk results to accepted risk criteria
• Review the options for managing and reducing the
  hazards and risks (i.e., alternate design and
  operating parameters, and accident control,
  reduction and mitigation strategies)

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Threat Spectrum(Courtesy of DND)
Greatest
Radio- Isotopes
Nuclear Weapons

• Most Likely High Yield Explosive (HYE)
• Most Dangerous Nuclear Weapons
• -----------------------------------------
• Greatest Threat Contagious Biological Pathogen

Least
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Example Hazard Identification
Immediate ignition

• Jet Fire
• Exposure to flame
• Exposure to heat
• Exposure to products

Delayed ignition

• Flash Fire
• Initial exposure (toxicity)
• Exposure to flame
• Exposure to heat
• Exposure to products

Uncontrolled release
No immediate ignition
No ignition

• Dispersing plume
• Exposure (toxicity)

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Safety Design and Optimization

• Compare alternative designs
• Assess control systems and operational parameters
• Compare risks to accepted standards

Generate alternatives and implementation
strategies
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Emergency Planning

• Recommendations for emergency planning zones and
  land-use
• Understand the nature and extent of the hazard
• Select the level of protection required
• Define an emergency planning zone (EPZ)
• Communicate findings

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Example Health and Safety Planning Priorities
Potential release source
Advance warning of an accident?
Area where other impacts may be experienced
Accident occurs
Plume disperses

• Area where chronic effects may be experienced
• Public health response area(shared
  responsibilities)
• Selection of health criteria

Exposure to dispersing plume

• Area where acute effects may be experienced
• Emergency Response Plan (responsibility of
  company)
• Selection of EPZ criteria

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Public Involvement and Communications

• Present an understanding of the hazards and risks
  at public meetings
• Preparation of materials for presentation to
  stakeholders
• Regulatory applications and expert testimony
• Corporate due-diligence and policy development

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Forensic Incident Analysis

• Accident investigation and reporting
• Describe the system
• Evaluate the meteorology during the event
• Recreate the incident
• What happened?
• Who was affected?

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Applications Hazard and Risk Assessments

• Safety design and optimization
• Recommendations for emergency planning zones and
  land-use
• Public involvement and communications
• Regulatory applications and expert testimony
• Corporate due-diligence policy
• Accident investigation and reporting

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The Heinrich Pyramid
Accidents
Incidents
Unreported Occurrences