NE 275: Principles and Methods of Risk Analysis

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NE 275 Principles and Methods of Risk Analysis

• Lecture 1 Introduction
• W.E. Kastenberg
• Fall 2003

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Historical Perspective
...the appearance of disease in human
populations is influenced by the quality of air,
water, and food the topography of the land and
general living habits.

the ancient-Greek physician Hippocrates in his
treatise Air, Water and Places


We Athenians in our persons, take our decisions
on policy and submit them to proper discussion.
The worst thing is to rush into action before
the consequences have been properly debated. We
are capable at the same time of taking risks and
estimating them before hand. Others are brave
out of ignorance But the man who can most truly
be accounted brave is he who best knows the
meaning of what is sweet in life, and what is
terrible, and he then goes out undeterred to
meet what is to come.

From Pericles Funeral Oration in Thucydides
History of the Peloponnesian War (started in
431 BC)
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Literal Definition of Risk

• Risk-- 1 possibility of loss or injury, 2 a
  dangerous element or factor, 3 the chance of
  loss, 4 the degree of probability of such loss,
  5 to expose to hazard or danger, 6 to incur the
  danger of.
• Safe--1 freed from harm or risk, 2 secure from
  threat of danger, harm or loss, 3 not liable to
  take risks.
• Safety--1 the condition of being safe from
  undergoing or causing hurt, injury, or loss, 2
  to protect against failure, breakage or accident.

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Principles of Risk Analysis

• What are the risks posed by technology on society
  and the environment? (Risk assessment)
• Are these risks acceptable? (Risk/benefit)
• Can these risks be reduced? (Option generation)
• On what basis should we choose among these
  options? (Value/impact or Cost/benefit)

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Risk Analysis Has Become an Important Tool in
Such Areas As

• Aerospace safety.
• Environmental restoration of contaminated sites.
• Improving safety at chemical process plants.
• Improving safety at electricity generation plants
  (fossil fueled and nuclear facilities).
• Setting conventional insurance rates.

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The Focus of Risk Assessment

• A focus on the factuala quantification of the
  undesirable consequences of technology such as
  human health effects and environmental
  degradation.
• Does not focus on the axiologicalthe evaluation
  of the unintended impacts of technology on the
  manner in which we live.

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Risk Assessment

• Risk assessment asks three questions
• 1. What can go wrong ?
• 2. How likely is it to happen?
• 3. What are the consequences?

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Types of Risk (Sequences and Consequences)
Consequence
Exposure
Event
Acute Effects
Acute
Latent Effects
Accidental Release
Latent Effects
Chronic
Chronic Release
Chronic
Latent Effects
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Quantifying the Risk of Accidents

• Risk - the expected value of an undesirable
  consequence
• i ith sequence
• fi frequency of occurrence
• xi consequence of undesirable
  event

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Fault and Event Trees (Frequency)
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Examples of Risk Measures

• Consequence or hazard Measure of risk
• Acute fatalities early deaths/ year
• Cancer death latent deaths/ year
• Contaminated land acres lost/ year
• Contaminated water concentration in drinking
  water or wells closed/ year
• Economic loss lost/ year
• Genetic effects mutations/ year
• Teratogenic effects birth defects/ year
• Neurological disease illness/ year
• Species loss species loss/ year
• Core melt events/ year

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How Does Risk Assessment Work?

• What are the risks from driving an automobile?
• There are 15,000,000 accidents per year, 1 in 300
  of which result in death, there are 250,000,000
  people

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Framework for Environmental Risk Assessment
Transport and transformation
Source/ Inventory

Emission
Exposure Events
Risk Mitigation
Dose/Response
Biokinetics
Uptake
Risk Characterization
Response
Dose