ML23200A225
| ML23200A225 | |
| Person / Time | |
|---|---|
| Issue date: | 07/19/2023 |
| From: | Tanya Smith Office of Nuclear Security and Incident Response |
| To: | |
| References | |
| Download: ML23200A225 (1) | |
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Exacting the Science of Emergency Preparedness HPS 68th Annual Meeting July 23-27, 2023 Todd Smith, PhD Senior Level Advisor for Emergency Preparedness and Incident Response Office of Nuclear Security and Incident Response U.S. Nuclear Regulatory Commission
NRC standards use evidence-based methods Nuclear power plant (NPP) operators must consider a range of protective actions, including evacuation and sheltering Guidelines for the choice of protective actions, consistent with Federal guidance, are developed and in place Evacuation time estimates (ETEs) have been developed by NPPs and are used in the formulation of protective action strategies ETEs are updated on a periodic basis
Deciding on action Protective Action Recommendation (PAR) recommended protective measure from the nuclear power plant to offsite response organizations (OROs)
Protective Action Decision (PAD) measures taken in response to an actual or anticipated radiological release Protective Action Guide (PAG) projected dose to an individual member of the public that warrants protective action Evacuate Shelter
Evacuation Time Estimate Study (NUREG/CR-7269)
Nonradiological Health Impacts of Evacuations and Relocations (NUREG/CR-7285)
Analysis of the Effectiveness of Sheltering-in-Place Use of Heating and Ventilation Systems while Sheltering-in-Place Dose Reduction Effectiveness of Masks Protective Action Decisionmaking in the Intermediate Phase (NUREG/CR-7248)
Emergency Planning Zone (EPZ) Size Methodology (RG 1.242)
Sensitivity of Dose Projections to Weather MACCS Consequence Model Improvements Impact on Protective Action Strategies (SAND2022-3706)
State-of-the-Art Reactor Consequence Analysis (SOARCA) Project (NUREG/CR-7110, NUREG/CR-7245)
NRC research enhances emergency preparedness
NUREG/CR-7269, Enhancing Guidance for Evacuation Time Estimate Studies State-of-the-art traffic simulation models used to better understand evacuation dynamics and to develop insights for protecting the public and first responders NRC research provides insights into effective evacuation
Shadow evacuation has minimal impact on those closest to release point Example Results for Large Population Site Model for various shadow participation rates (by percent)
Automated traffic control (ATC) is as effective as manual traffic control (MTC)
Example Results for Large Population Site Model Large Population Site Model
The sensitivity of important parameters is known Population Mobilization Time Background and Heavy Vehicle Traffic Roadway Impact Free-flow Speed Adverse Weather Processing Time Step Random Seed Uncertainty Demand Variables Supply Variables Process Variables
Meta-analysis of Odds Ratio for All Health Effects Assessing the balance of the risk NUREG/CR-7285, Nonradiological Health Consequences of Evacuation and Relocation Meta-analysis of the impact of prolonged displacement across all types of emergency events
Analyzing the protection of shelters
= + 1
Current dose reduction factors estimate shelter effectiveness Shelter effectiveness can also be examined through dynamic models and lessons from other hazards to provide additional insight U.S. EPA. EPA-400/R-17/001, PAG Manual: Protective Action Guides and Planning Guidance for Radiological Incidents, Office of Radiation and Indoor Air, January 2017.
Smith, Todd R. Transforming Protective Action Strategies for Radiological Emergencies Exacting the Science of Sheltering-in-Place. Oregon State University, 2021.
Exploring effective use of shelters and ventilation Dust storms (Argyropoulos, 2020)
Modeled office building (Kulmala, 2016)
Monte Carlo simulations (Thornburg, 2001)
Quantifying the benefits of masks
NUREG/CR-7248, Capabilities and Practices of Offsite Response Organizations for Protective Actions in the Intermediate Phase of a Radiological Emergency Response Shared understanding of offsite response organization capabilities and practices for protecting the public after the emergency phase.
- Monitoring
- Relocation & reentry
- Food condemnation
- Drinking water
- Actions beyond the EPZ ORO Study Topics Best Practices identified for Communicating with the public Developing partnerships and sharing resources for monitoring Making situation-dependent decisions based on science Leveraging technology Assisting vulnerable populations, livestock, and pets Gathering and sharing best practices
NRC provides evidence to support protective actions
What is MACCS?
- Probabilistic consequence analysis tool for developing realistic estimates of consequences of nuclear power plant incidents
- Developed by NRC and Sandia National Laboratory
- Extensive use by NRC and domestic and international organizations How is MACCS used?
- Consequence studies
- Level 3 Probabilistic Risk Assessment (PRA)
- Cost-benefit analysis
- Risk-informed decision-making Consequence analyses support risk-informed decisions https://maccs.sandia.gov/
Emergency Phase Modeling Protective actions (evacuation, sheltering, relocation, KI)
Cohort timeline (general population, schools, special facilities, evacuation tail, shadow evacuees, non-evacuees)
How parameters are informed Evacuation time estimate (ETE) studies and traffic simulation models (NUREG/CR-7269)
MACCS modeling best practices Discussions with state and local authorities (NUREG/CR-7248)
Modeling in MACCS to inform protection strategies NUREG/CR-7009, MACCS Best Practices as Applied in the State-of-the-Art Reactor Consequence Analyses (SOARCA) Project, August 2014 NUREG/CR-7270, Technical Bases for Consequence Analyses Using MACCS (MELCOR Accident Consequence Code System), October 2022
Current NRC guidance for protective action strategies is based on a study completed in 2010 PAR Study Guidance
Different actions provide different benefits
- NUREG/CR-6953 studied alternative evacuation strategies to reduce public dose during severe accidents.
Radial Lateral Staged NUREG/CR-6953, Review of NUREG-0654, Supplement 3, Criteria for Protective Action Recommendations for Severe Accidents, https://www.nrc.gov/reading-rm/doc-collections/nuregs/contract/cr6953/index.html
Scoping Analysis of MACCS Model Improvements for Study of PARs https://adamswebsearch2.nrc.gov/webSearch2/main.jsp?AccessionNumber=ML22096A090 How would MACCS model updates impact the performance of a PAR Study?
Updated models
- Added keyhole evacuation model
- Capability to model up to 500 plume segments
- Added HYSPLIT Atmospheric Transport and Dispersion Model (ATD) in addition to Gaussian
- Enhanced nearfield modeling for building wake effects
- Economic model update
- Release from multiple sources Parameter input selection
- Source terms (non-light-water reactor)
- Timing of protective actions and cohort selection
- Dose coefficients, shielding and exposure factors
Refined spatial grid resolution better reflects population data, site characteristics, and meteorology 16 compass sectors 64 compass sectors
NRCs ETE Study provides useful data to inform model parameters Temporal Speed Data Representations
Input via text files or GUI Updated parameter values applied to MACCS models Spatial Speed Data Representations
Source term characteristics are key drivers of risk estimates PAR Study examined rapidly progressing scenario Other realistic accident scenarios progress more slowly Accident timing and release characteristics have large impact on potential consequence estimates
Scoping Analysis of MACCS Model Improvements for Study of PARs https://adamswebsearch2.nrc.gov/webSearch2/main.jsp?AccessionNumber=ML22096A090 Analysis Conclusions Not recommending changes to current protective action strategy guidance Scoping analysis showed fewer potential health consequences than the original PAR study Choice of source term had largest impact Source term coupled with keyhole evacuation model impacted the number of displaced individuals Minimal impact of updated shielding parameters Analysis provides assessment of updated MACCS modeling capabilities and insights into parameter sensitivity to inform future efforts
Our understanding of source terms has evolved NUREG/BR-0359, Revision 3, Modeling Potential Reactor Accident ConsequencesState-of-the-Art Reactor Consequence Analyses: Using decades of research and experience to model accident progression, mitigation, emergency response, and health effects, October 2020
and continues to evolve
Exacting the science of emergency preparedness prepares us for a safe tomorrow
For more information
References:
1.
U.S. NRC. NUREG/CR-7248, Capabilities and Practices of Offsite Response Organizations for Protective Actions in the Intermediate Phase of a Radiological Emergency Response, June 2018. https://www.nrc.gov/reading-rm/doc-collections/nuregs/contract/cr7248/index.html 2.
U.S. NRC. NUREG/CR-7269, Enhancing Guidance for Evacuation Time Estimate Studies, January 2020.
https://www.nrc.gov/reading-rm/doc-collections/nuregs/contract/cr7269/index.html 3.
U.S. EPA. EPA-400/R-17/001, PAG Manual: Protective Action Guides and Planning Guidance for Radiological Incidents, Office of Radiation and Indoor Air, January 2017.
Smith, Todd R. Transforming Protective Action Strategies for Radiological EmergenciesExacting the Science of Sheltering-in-Place. Oregon State University, 2021. https://ir.library.oregonstate.edu/concern/graduate_thesis_or_dissertations/pk02cj32m?locale=en 5.
U.S. NRC. NUREG/CR-7285, Nonradiological Health Consequences of Evacuation and Relocation, August 2021.
https://www.nrc.gov/reading-rm/doc-collections/nuregs/contract/cr7285/index.html 6.
U.S. Federal Emergency Management Agency. Protective Actions Research, Web page, last accessed January 2022.
https://community.fema.gov/ProtectiveActions/s/
Todd Smith, PhD Senior Level Advisor for Emergency Preparedness and Incident Response todd.smith@nrc.gov