admlc uncertainty workshop · admlc uncertainty workshop 3 may 2017 impact of uncertainties on...
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ADMLC uncertainty workshop 3 May 2017
Impact of uncertainties on early health protection
decisions in radiation emergencies and applicability
to other fields
Stephanie Haywood
Centre for Radiation, Chemicals and Environmental Hazards
Public Health England
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This presentation outlines…
• Outlines uncertainty in early dose assessments in a nuclear or
radiological emergency
• Implications of this uncertainty for public health advice and
presenting uncertain information
• Some problems - which may relate to other situations
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Early emergency assessments
• Need rapid decisions on health protection
• What potentially significant information is not yet known?
• Hazards of unneeded countermeasures (eg risks of
unnecessary evacuation)
• Hence need to be able to explain the uncertainty in dose
estimates to decision-makers
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Emergency assessments
Accidental
release
Assessments Contamination pattern
Doses
Countermeasures
advice sheltering
stable iodine
evacuation etc
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Site
data
Estimated
source
term
Measurements
Weather Dispersion &
deposition
modelling
Dose
modelling
Environmental
modelling
Inputs to
assessments
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Emergency assessments
Accidental
release
Assessments Contamination pattern
Doses
Countermeasures
advice sheltering
stable iodine
evacuation etc
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Site
data
Estimated
source
term
Measurements
Weather Dispersion &
deposition
modelling
Dose
modelling
Environmental
modelling
All components
contain uncertainties,
and calculations
are approximations
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Uncertainties in assessments include … • what has been released (amounts and radionuclides)
• what the time distribution of the release is likely to be
• features of the release (eg particle size and release energy)
• what influence the weather has had so far
• future weather – may be several/many alternative predictions
• monitoring data – how reliable, is it being interpreted correctly?
• combinations of uncertainty – eg increase in amount released
coinciding with change in weather such as onset of rain
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Uncertainties in assessments include … • what has been released (amounts and radionuclides)
• what the time distribution of the release is likely to be
• features of the release (eg particle size and release energy)
• what influence the weather has had so far
• future weather – may be several/many alternative predictions
• monitoring data – how reliable, is it being interpreted correctly?
• combinations of uncertainty – eg increase in amount released
coinciding with change in weather such as onset of rain
How to deal with these in assessments?
How to present the results to decision-makers?
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• Work in the UK (Warwick University, UK Met Office, PHE) –
funded by ADMLC - described later
• Developing techniques for presenting uncertainty to decision-
makers, focusing on radiological emergencies
• Workshops of UK government experts and agencies have
explored how uncertainty is understood and what is needed in
presentation
Presenting uncertain information
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Some conclusions (1)
• Predicting consequences of radiation accidents in early
hours long recognised to have many uncertainties
• Many decision support systems developed in the last 20
years – few do uncertainty and none do it comprehensively
• Where done, the emphasis is on weather permutations
• Source term uncertainty seldom if ever included
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Some conclusions (2)
• The assumptions on which the analyses are built are often
pessimistic …
• … and concentrate on worst case doses, not other
outcomes (eg agricultural effects or economic impact)
• Interactions between uncertainties eg release duration and
weather ignored
• A more comprehensive treatment of the key uncertainties is
needed for providing advice to decision makers
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Does the view of uncertainty vary depending on who you are?
eg scientists, government decision-makers, public,
media
Is uncertainty likely to be well-received by decision–makers in
an emergency?
• is it likely to be appreciated as offering greater insight?
• or will it be seen as an unwelcome complication?
How can it be made to be the expected format?
Additional thought for discussion
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Any questions?
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