ML25142A178
| ML25142A178 | |
| Person / Time | |
|---|---|
| Issue date: | 05/14/2025 |
| From: | Tanya Smith NRC/NSIR/DPR |
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| Download: ML25142A178 (1) | |
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Radiological Emergency Preparedness:
How Risk-informed Regulation Prepares Us for the Future Regional Radiological Emergency Preparedness Conference May 14, 2025 Todd Smith, PhD Senior Level Advisor for Emergency Preparedness and Incident Response Office of Nuclear Security and Incident Response U.S. Nuclear Regulatory Commission
Whats driving change?
Technology is advancing
Advanced light water reactors, non-light water reactors, and small modular reactors (SMR) with passive safety features, microreactors, accident tolerant fuels, and other new technologies (ONT)
Technology important to EP (e.g., IPAWS, artificial intelligence)
Knowledge is increasing
Better understanding of effects of radiation
Research to inform protective action decision-making
Lessons learned from real world events Regulations and guidance are evolving
NRC has a vision to become a modern risk-informed regulator
Nuclear Energy Innovation and Modernization Act (NEIMA)
Accelerating Deployment of Versatile, Advanced Nuclear for Clean Energy (ADVANCE) Act
EP is like bedrock in a changing landscape Radiological emergency preparedness ensures protective actions can and will be taken is an independent layer of defense in depth provides dose savings is risk-informed
The NRC applies a graded approach to EP A graded approach is a risk-informed process in which the safety requirements and criteria are set commensurate to facility hazards Existing NRC regulations have always used a graded approach to EP
Power reactors (low-power testing, power operations, decommissioning)
Research and test reactors
Fuel Fabrication Facilities
Independent Spent Fuel Storage Installations
Monitored Retrievable Storage
Roles and responsibilities are defined
Reasonable assurance is not absolute assurance Our emergency planning requirements do not require that an adequate plan achieve a preset minimum radiation dose saving or a minimum evacuation time for the plume exposure pathway emergency planning zone in the event of a serious accident.
It is implicit in this concept of adequate protective measures that a determination that a particular EPZ size will provide adequate protective measures does not in fact mean that emergency planning will eliminate, in every conceivable accident, the possibility of serious harm to the public.
[Shoreham CLI-86-13, 24 NRC 22, 30 (1986)]
Plans are useless, but planning is indispensable Emergency Preparedness:
Reduces complex decision-making in an emergency Simplifies the choice of possible responses Allows for consistent and practiced approaches Addresses a spectrum of challenges irrespective of causes
- Dwight D. Eisenhower
What should be the planning basis?
In the 1970s, the Conference of Radiation Control Program Directors asked, What is the accident we should be planning for? What is the planning basis?
A combined NRC and EPA Task Force considered different bases:
Risk not used as a basis for planning for other hazards public has subjective perception of risk (intuitive vs. quantitative) would require setting an acceptable level of risk (out of scope)
Probability society tolerates more probable events without specific planning however, accident probability provides perspective Cost effectiveness NUREG-0396, Planning Basis for the Development of State and Local Government Radiological Emergency Response Plans in Support of Light Water Nuclear Power Plants, November 1978
Preparedness begins with a proven planning basis The consequences from a spectrum of accidents, tempered by probability considerations, should be considered to scope the planning efforts for The distance to which planning for predetermined protective actions is warranted The time dependent characteristics of a potential release The type of radioactive materials NUREG-0396, Planning Basis for the Development of State and Local Government Radiological Emergency Response Plans in Support of Light Water Nuclear Power Plants, November 1978
Planning distance The distance to which planning for predetermined protective actions is warranted The EPZ is a planning tool:
it was the consensus of the Task Force that emergency plans could be based upon a generic distance out to which predetermined actions would provide dose savings beyond the generic distance it was concluded that actions could be taken on an ad hoc basis The EPZ guidance does not change the requirements for emergency planning, it only sets bounds on the planning problem.
NUREG-0396, Planning Basis for the Development of State and Local Government Radiological Emergency Response Plans in Support of Light Water Nuclear Power Plants, November 1978
EPZ simplifies decisions for a prompt response Protective Action Guide (PAG) projected dose to an individual member of the public that warrants protective 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 PAG PAR PAD PAG PAR PAD
The EPZ is scalable in size EPZ size based on the consequences from a spectrum of accidents, tempered by probability considerations.
NRC regulations provide for scalable EPZs Reactors have been approved for a 5-mile EPZ in the past Depending on facility type, the EPZ may be at the site-boundary or no EPZ Considerable number of studies since the 1980s on sizing EPZs for passive and advanced reactor designs, many based on the NUREG-0396 methodology
Considerations for EPZ size The size of the EPZ is based on the following considerations:
a.
Projected doses from traditional design basis accidents would not exceed Federal PAG levels outside the EPZ b.
Projected doses from most core melt sequences would not exceed Federal PAG levels outside the EPZ c.
For the worst-case core melt sequences, immediate life-threatening doses would generally not occur outside the EPZ d.
Detailed planning within [the EPZ] would provide a substantial base for expansion of response efforts in the event that this proved necessary NUREG-0396, Planning Basis for the Development of State and Local Government Radiological Emergency Response Plans in Support of Light Water Nuclear Power Plants, November 1978
The EPZ size is risk-informed Design Basis Accidents Beyond Design Basis
EP is a matter of judgment A reading of the Report [NUREG-0396] indicates clearly that the margins of safety provided by the recommended 10-mile radius were not calculated in any precise fashion but were qualitatively found adequate as a matter of judgment.
[55 FR 5605, Feb 16, 1990]
EPZ methodology can be applied to any facility EPRI TR-113509, Technical Aspects of ALWR Emergency Planning, Final Report, September 1999
Whats the likelihood of events considered?
NUREG-075/014 (WASH-1400), Reactor Safety Study: An Assessment of Accident Risks in U.S. Commercial Nuclear Power Plants, October 1975
down to 1 chance in 10 lifetimes of the universe NUREG-075/014 (WASH-1400), Reactor Safety Study: An Assessment of Accident Risks in U.S. Commercial Nuclear Power Plants, October 1975
Worst-case is addressed in the planning Regulation does not require dedication of resources to handle every possible accident that can be imagined. The concept of the regulation is that there should be core planning with sufficient planning flexibility to develop reasonable response to those very serious low probability accidents which could affect the public.
[SONGS CLI-83-10, 17 NRC 528, (1983)]
Federal and state capabilities are available The Task Force believes that it is not appropriate to develop specific plans for the most severe and most improbable Class 9 events.
The Task Force, however, does believe that consideration should be given to the characteristics of Class 9 events in judging whether emergency plans based primarily on smaller accidents can be expanded to cope with larger events.
The planning basis recommended by the Task Force therefore includes some of the key characteristics of very large releases to assure that site specific capabilities could be effectively augmented with general emergency preparedness (response) resources of the Federal government should the need arise.
NUREG-0396, Planning Basis for the Development of State and Local Government Radiological Emergency Response Plans in Support of Light Water Nuclear Power Plants, November 1978
EP involves the Whole Community Facility State/Local Federal
Planning time The time dependent characteristics of a potential release NUREG-0396, Planning Basis for the Development of State and Local Government Radiological Emergency Response Plans in Support of Light Water Nuclear Power Plants, November 1978
Effectiveness of protective action related to timing The guidance cannot be very specific because of the wide range of time frames associated with the spectrum of accidents considered.
Therefore, it will be necessary for planners to consider the possible different time periods between the initiating event and arrival of the plume and possible time periods of release in relationship to time needed to implement protective actions.
NUREG-0396, Planning Basis for the Development of State and Local Government Radiological Emergency Response Plans in Support of Light Water Nuclear Power Plants, November 1978
Bound the timing of severe accidents NUREG-075/014 (WASH-1400), Reactor Safety Study: An Assessment of Accident Risks in U.S. Commercial Nuclear Power Plants, October 1975
Time basis informs functional requirements nuclear power reactor licensees shall establish and maintain the capability to assess, classify, and declare an emergency condition within 15 minutes after the availability of indications to plant operators that an emergency action level has been exceeded A licensee shall have the capability to notify responsible State and local governmental agencies within 15 minutes after declaring an emergency The design objective of the prompt public alert and notification system shall be to have the capability to essentially complete the initial alerting and initiate notification of the public within the plume exposure pathway EPZ within about 15 minutes Appendix E to 10 CFR Part 50
Release characteristics inform EP functions The type of radioactive materials NUREG-0396, Planning Basis for the Development of State and Local Government Radiological Emergency Response Plans in Support of Light Water Nuclear Power Plants, November 1978
WASH-1400 informed early understanding NUREG-0396, Planning Basis for the Development of State and Local Government Radiological Emergency Response Plans in Support of Light Water Nuclear Power Plants, November 1978
Our understanding of accidents 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
The landscape of nuclear is changing ARDP Awardees ARC-20 Demo Reactors In Licensing Review Risk Reduction Preapplication RTR Research/Test Reactor LEGEND High-Temperature Gas-Cooled Reactors (HTGR)
Liquid Metal Cooled Fast Reactors (LMFR)
Molten Salt Reactors (MSR)
TRISO Fuel Westinghouse Columbia Basin Hydromine Lead-Cooled Micro Reactors Framatome X-energy (Xe-100)*
StarCore MIT General Atomics*
General Atomics (EM2)
- GEH PRISM (VTR)
ARC Clean Technology
- TerraPower/GEH (Natrium)*
Sodium-Cooled Kairos (Hermes l RTR)
Liquid Salt Cooled Kairos
- ThorCon Flibe Elysium Alpha Tech Muons Southern (TP MCRE) l RTR ACU l RTR Terrestrial
- TerraPower (MCFR)
Liquid Salt Fueled UIUC / Ultra Safe l RTR*
Stationary Oklo
- Small Modular Light Water Reactors Boiling Water Reactor GEH BWRX-300*
Holtec SMR-300
- Pressurized Water Reactors Westinghouse AP300*
NuScale US600 NuScale US460 Westinghouse (eVinci)
- BWX Technologies X-energy Radiant
- Alpha Tech Nano Nuclear Energy Ultra Safe Nuclear Transportable
NRC is Advanced Reactor Ready https://www.nrc.gov/reactors/new-reactors.html
Major provisions of alternative EP regulations The final rule in 10 CFR 50.160 provides an alternative framework for small modular reactors and other new technologies:
regulatory framework proportional to facility risks required EP functions set commensurate to radiological risk (consequences) technology inclusive, performance based performance demonstration in drills and exercises hazard analysis for contiguous facilities ingestion planning capabilities scalable EPZ according to planning needs
Emergency response functions provide capabilities Event classification and mitigation Protective actions Communications Command and control Staffing and operations Radiological assessment Re-entry Critiques and corrective actions
Planning activities ensure readiness Prepare and issue public information during emergencies Implement the emergency plan in conjunction with the safeguards contingency plan Voice and data communications with the NRC Identify emergency facilities where effective direction and control can be exercised in an emergency Site familiarization training for offsite support Maintain the emergency plan
Planning requires coordination and communication Reasonable assurance needed for planning elements within an EPZ beyond the site boundary:
contacts and arrangements public protective actions evacuation time estimate within the EPZ primary and backup offsite response facilities making and communicating dose projections periodic public emergency planning information and alert & notification general re-entry plans after an emergency drill and exercise programs with offsite response
Hazard analysis identifies other considerations Address the impact on emergency plan implementation from:
contiguous or nearby facilities and other credible hazards potential impacts of industrial plants, other reactors, transportation systems, or combination of factors site-specific, credible hazards from other facilities that may require additional EP considerations
Scalable EPZ to support planning needs The EPZ determination considers form and function:
the area within which public dose is projected to exceed 10 mSv TEDE over 96 hours0.00111 days <br />0.0267 hours <br />1.587302e-4 weeks <br />3.6528e-5 months <br /> considering:
accident likelihood source term timing of the accident sequence meteorology the area within which predetermined, prompt protective measures are warranted
Ingestion pathway planning is in place Emphasizes capabilities and readiness to respond Identification of major exposure pathways for ingestion Identify resources available at all levels of government to sample, assess, and implement a quarantine or embargo of food and water to prevent ingestion
Technology propels the future of EP Integrated Public Alert and Warning System Digital Twins Artificial Intelligence Geographic Information Systems Federal capabilities
Key takeaways on Emergency Preparedness EP ensures protective actions can and will be taken EP regulations are risk-informed and commensurate to the potential hazards presented by the class of facility Informed by characteristics of a spectrum of accidents EP is not based on risk or probability of an accident occurring Requires judgmentbacked by evidence
Risk-informed, performance-based EP regulation prepares us for the future