Risk, Safety and Ethics: Social Benefit Vs' Risk

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Risk, Safety and Ethics Social Benefit Vs.
Risk

• P.F. Peterson
• NE 39

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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 Hypocrites 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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What Is Risk? What is Safety?
Risk 1. Possibility of loss or injury.
2. A dangerous element or factor. 3.
The chance of loss. 4. A person or
thing that is a specified hazard.


Safe 1. Freed from harm or risk. 2.
Secure from treat of danger, harm
or loss. 3. Affording safety from
danger.
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Risk Analysis

• What are the risks imposed by human activities
  and natural phenomena? (Risk Assessment)
• Are these risks acceptable? (Risk Valuation)
• Can these risks be reduced? (Option Generation)
• How can the options be evaluated? (Cost/Benefit)

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Risk Assessment

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

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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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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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Fault and Event Trees
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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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Risk From Radioactive Materials and Toxic
Chemicals in the Environment

• Risk is a function of exposure toxicity
• How much of the toxic material is the individual
  going to be exposed to?
• What amount of toxic material is likely to cause
  an adverse health effect?
• Location and strength of source (Qij)
• Model the spread of the plume (Xi)
• Model the exposure to human or other species
  (Eij)
• Model the dose response relationship (DRi)

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Risk Assessment

• Hazard identification uses toxicology (cell,
  tissue and animal tests) and epidemiology
  (population data and field samples)
• Exposure assessment includes determination of
  sources, environmental concentrations, exposure,
  dose, and uncertainties

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A Multimedia, Multiple Pathway Exposure Model
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Environmental Fate and Transport
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Inter-media Transfers

• Air and soil to food

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Multiple Exposure Pathways
Inhalation
Activity Patterns
Dermal
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Mechanism of Action

• Whether a compound reaches a target tissue
  depends on
• Absorption through the GI tract, lung, or skin
• Distribution in the body
• Biotransformation
• Excretion

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Qualitative Safety Goals

• Individuals bear no significant additional risk
  to life and health from the operations of a
  nuclear power plant.

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Qualitative Safety Goals

• Individuals bear no significant additional risk
  to life and health from the operations of a
  nuclear power plant.
• Societal risks to life and health from nuclear
  power plant operation should be comparable to or
  less than the risks due to electric generation by
  competing technologies and should not be a
  significant addition to other societal risks.

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Quantitative Safety Goal 1

• Risk to the average individual in the vicinity of
  a nuclear power plant of prompt fatalities that
  might result from reactor accidents should not
  exceed one-tenth of one percent (0.1 percent) of
  the sum of prompt fatality risks resulting from
  other accidents to which members of the US
  population are generally exposed.
• There are 100,000 accidental deaths in the US
  every year, so the safety goal is
• 0.001 (105 per year) / 2.8 X 108 3.6 X 10-7
  per year .

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Quantitative Safety Goal 2

• The risk to the population in the area near a
  nuclear power plant of cancer fatalities that
  might result from nuclear power plant operation
  should not exceed one-tenth of one percent (0.1
  percent) of the sum of cancer fatality risks
  resulting from all other causes.
• There are 20 cancer deaths per year, per 10,000
  people. Hence 0.001 (20/10,000) 2 X 10-6/ year,
  so that for a population of 2 million people
  living in the vicinity of a nuclear power plant,
  the goal is 4 statistical deaths per year.
• There are between 20 and 80 statistical cancer
  deaths per year for a comparable (in size and
  population) coal fired power plant.

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For Reactor Safety we analyze the frequency and
consequences of Licensing Basis Events

• LBEs may be generated by internal or external
  events
• LBEs are categorized by frequency

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Frequency of LBEs involves slow phenomena
(intervals of of months to millions of years)

• LBE frequency analysis depends upon slowly
  evolving phenomena
• Reactor development paths should include separate
  effects tests (material and fuel irradiation,
  etc.) and reliability testing of major system
  components in Component Test Facilities
• AOO frequency prediction is also important for
  economics (affects the plant capacity factor)

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Plant response to LBEs involves rapid phenomena
(seconds to days)

• Code Scaling, Applicability and Uncertainty
  Analysis (CSAU) methodology is applied to predict
  the system response to LBEs
• Transient response code must be validated against
  Separate Effect Test and Integral Effect Test
  experiments