Transcript Discussion of EP Basis Project Objectives and Approach

Industry Emergency Planning Protective Action
Strategy Study
Presented to NREP Conference
Harrisburg, PA
Presented by
David E. Leaver, Polestar Applied Technology, Inc.
Alan Nelson, Nuclear Energy Institute
John Gaertner, EPRI
April 13, 2005
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Topics for Discussion
1. Risk-informed (R-I) evaluation of KI to 20 Miles
2. EP protective action strategy project
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KI to 20 Miles
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HHS guidelines are to be issued for public comment; expect 60 day
comment period – comment period may not be until 3rd quarter
Preliminary response by states indicates that a number of states are not
particularly happy about programs to stockpile and distribute KI
NEI, with EPRI and Polestar support, is reviewing these guidelines
Objective of EPRI and Polestar work is to perform a R-I evaluation of use of
KI in the range of 10 to 20 miles
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KI to 20 Miles (continued)
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EP is part of a defense-in-depth process that is based on taking prudent
measures to provide reasonable assurance of adequate protection to the public
While the existence of the emergency plan is not strictly based on R-I or costbenefit considerations, it is instructive, and consistent with increasing use of R-I
approaches, to consider incremental changes to the existing plan in this context
The R-I methodology for evaluating KI is as follows:
– Calculate thyroid dose exposure for a set of accident scenarios (used MACCS2
software)
– Calculate the risk averted from administering KI
– Consider the benefit of this averted risk in terms of thyroid injury costs avoided
– Estimate the costs of a KI stockpiling and distribution program for 10 to 20 miles
– Compare the cost of the program with the benefit of risk averted
– Treat uncertainties in important parameters by assigning a distribution for the
parameter value
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KI to 20 Miles (continued)
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Assumptions
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Assess all population groups which are potentially vulnerable to thyroid injuries
Inhalation thyroid dose only (no ingestion effect)
Cost of KI program for 20 miles based on a multiple of 10 mile EPZ KI cost
Sites in several states were evaluated and included lower and higher population sites
Used PRA accident scenarios, including those from terrorist attack
Assumed that KI was available to 30% to 70% of the people who are exposed (based
on NAS study, Table 6.12) and that 50% of these people use the KI in a timely
manner
– Benefit of an averted thyroid injury was based on estimates of the direct costs
(medical treatment), indirect costs (time and output lost), and possible psychological
and injury claim costs
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KI to 20 Miles (continued)
100%
Cumulative Probability
80%
10 - 20 mile
region
60%
5 - 10 mile
region
40%
0 - 5 mile
region
20%
0%
1
10
100
1000
10000
100000
Cost-Benefit Ratio
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KI to 20 Miles (continued)
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Preliminary results of R-I evaluation
– The cost-benefit ratio (i.e., the ratio of the cost of the KI program to the benefit of
the averted thyroid dose) in the 10 to 20 mile region is in the range of 100 –
10,000
– Even in the 0 to 10 mile region the cost benefit ratio is not favorable, except
possibly within a few miles of the site
– If there was a serious plant accident at an average U.S. site (a very unlikely
event), the expected number of thyroid injuries in the 10 – 20 mile region, if any,
would be small
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KI to 20 Miles (continued)
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Observations on KI to 20 miles
– KI is safe and can be effective in emergency response as a supplement to
evacuation and sheltering in a plume exposure region (within a few miles of the
site)
– KI is not the most effective protective measure in an ingestion pathway zone
(beyond 10 miles)
– Extending KI to 20 miles is a relatively high cost to address low risk
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Protective Action Strategy Project
Project objectives
1. Provide a methodology for defining smarter protective action strategies that:
a. Have the potential to significantly reduce public risk from a range of accidents
b. Take better advantage of today’s communication technology
c. Are consistent with current warning response research results
d. Are cost effective in a R-I framework
2. Provide a more sound, updated technical basis for EP, including consideration of R-I
methods
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The work is being sponsored by NEI and EPRI
The work will be generic in nature (i.e., typical PWR and BWR, a generic, high
population (and possibly low population) density site, generic methodology for
evaluation of protective action strategies)
NRC staff is engaged in a similar project as directed by the Commission in October,
2003 SRM; industry and NRC are exchanging information and results on these
respective efforts to improve overall project effectiveness and efficiency
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Main Tasks in Protective Action Strategy Project
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Define updated source terms to be used as basis for EP
Define a R-I framework for consideration of EP effectiveness
Develop site parameters
Develop consequence model
Assess improved protective action strategies
Evaluate margin in 10 mile plume exposure EPZ
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Description of Tasks
1. Source Term Task
a. Treat EP as a prudent, defense-in-depth measure regardless of the probability of
a serious accident
b. Rather than using “worst-case scenarios”, use realistic conservatism so the
accident scenarios used as the basis for the offsite emergency response plan
are recognizable, usable, and practical
c. Base EP primarily on a range of consequences, including potential terrorist
accidents, with accident sequence frequency as an additional consideration
d. Recognize that events used in the EP basis must meet some reasonable
threshold of credibility (~10-7 per year)
e. Confirm that events which are below the threshold of credibility would:
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Not significantly impact the risk metric
Be addressed by the same types of protective action strategies being developed for
events which are in the EP basis
f. Document the set of release categories to be used for EP in a manner that
discourages misuse of the results (the calculation of disastrous results for highly
improbable or unrealistic events helps no one, wastes resources, and frequently
results in unnecessary public fear)
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Description of Tasks (continued)
2. R-I Framework
– Risk metrics* are being defined to provide a measure of the effectiveness of
various protective action strategies in a R-I framework
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Early fatality risk
Latent cancer risk
Thyroid cancer risk
– For example, the risk metric on early fatality risk will be related to the safety goal
to define what is an acceptable and cost-effective level of defense-in-depth from
emergency response
* This will be similar in concept to the core damage frequency (CDF) and large early release
frequency (LERF) metrics in RG 1.174 (i.e., an x vs. y plot where the baseline risk metric is
along the x-axis, and the change in that metric is along the y-axis).
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Description of Tasks (continued)
3. Definition of Site Parameters
– It is intended to use a generic site for this work
– A high population density generic site will be used, and resources permitting, a
low population density site
– Upon successful demonstration of the consequence model, site specific
calculations could be done if appropriate
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Description of Tasks (continued)
4. Develop Consequence Model
– The objective of the consequence model is to allow statistical assessment of the
risk implications of a variety of protective action strategies in order to develop a
basis for preferred, cost-effective strategies
– The approach for the consequence model is to use MACCS2 where applicable
and to develop new software modules where necessary to address limitations in
MACCS2
– The limitations in MACCS2 which need to be addressed are:
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Providing more flexibility and realism in describing protective action strategies (e.g.,
several cohorts with different mobilization times, shelter vs. evacuation, evacuation
directions, and evacuation speeds)
Allowing dynamic (runtime) definition of protective action strategies according to the
weather condition and time of day, day of week, etc. when the protective action
decisions are made
Evaluating the impact of wind shift on plumes and on predicted risk
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Description of Tasks (continued)
5. Assess Improved Protective Action Strategies
– Using the consequence model, assess the effectiveness of various protective
action strategies which could depend upon weather, wind speed and direction,
information contained in the plant notification, time of day, location of cohort, etc.
– Define protective action strategy to be simple but effective:
• Reduce early health effect risk and reduce overall dose
• Be cost-effective as measured by risk metrics
• Be simple enough to be implementable by ORO and understood by the
public
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Description of Tasks (continued)
5. Assess Improved Protective Action Strategies (continued)
– The protective action strategies that result from this work are likely to be
somewhat more specific (e.g., directional evacuation, staged evacuation and
sheltering) than what is typically utilized in EPZs today
– Because of this, the strategies should consider the social psychology of the
public in the EPZ
– Observations thus far on social psychology of the EPZ:
• It is expected that the public in the EPZ will cooperate in an emergency
• It may be a good idea at some point to do a social psychology design of the
emergency warning information dissemination portion of any new strategy
so as to help the OROs maximize the effectiveness of the PAS
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Description of Tasks (continued)
5. Assess Improved Protective Action Strategies (continued)
– Examples of the types of potentially improved protective action strategies and
related information to be considered include:
• Evacuation away from plume (e.g., in sideways direction)
• Evacuation from near site areas (e.g., 1 or 2 miles) by walking
• Evacuation-to-shelter inside the EPZ
• Staged evacuation (e.g., initially shelter, then evacuate)
• Making roads one-way in near site areas
• Use of historical weather data to provide insights on pre-planned strategies
• Capability and role of real-time plume monitoring
• Real-time optimization of protective actions (feedback and redirection)
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Description of Tasks (continued)
6. Evaluate Margin in 10 mile EPZ
– Perform an evaluation using the updated source terms to confirm that margin
exists in the 10 mile plume-exposure EPZ
– Update the methodology used in NUREG-0396 with more of a R-I approach
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Protective Action Project Deliverables
and Schedule (continued)
Deliverables
• Generic models for evaluating effectiveness of protective actions
• A final report documenting the results and the updated, R-I technical basis
for EP
• The final report may be published as an NEI report similar to NEI 99-01,
revision 4, which addressed EALs and was reviewed and endorsed by NRC
Schedule
• Limited results are expected by mid-2005 in order to support information
exchange with NRC
• Completion of the main body of the work is anticipated to require about 2 or
2 ½ years
• A pilot project may be appropriate at some point to confirm the feasibility of
the process of defining PAS on a site specific basis and incorporate lessons
learned (similar to ROP effort)
• A peer review process could also be considered
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Protective Action Project Deliverables
and Schedule (continued)
Industry – NRC Interaction
• Meetings were held at Sandia between industry and NRC teams last fall
and again this spring
• Plans are evolving for comparison calculations to be performed to allow
benchmarking the industry model against NRC results later this year
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