ML23032A466

ANS Riep Wg - EP Planning Basis - February 2023

ML23032A466
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Issue date:	02/01/2023
From:	Tanya Smith NRC/NSIR/DPR
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Planning Basis for Radiological Emergency Preparedness

American Nuclear Society (ANS)

Risk-informed Emergency Preparedness (RIEP) Working Group Februar y 1, 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 The NRC employs a graded approach to EP

• A graded approach is a process by which the safety requirements and criteria are set commensurate with several factors including magnitude of hazards involved, characteristics of a facility, the balance between radiological and nonradiological hazards.

• EP regulations employ a graded approach, which is a risk-informed p ro c e s s Power reactors (low-power testing, power operations, decommissioning)

Research and test reactors Fuel Fabrication Facilities Independent Spent Fuel Storage Installations Monitored Retrievable Storage Objective of Radiological EP

• The objective of emergency preparedness (EP) is to provide dose savings for a spectrum of accidents that could produce doses in excess of the Environment Protection Agency (EPA) protective action guides (PAG)

• Meeting NRC EP regulations provides reasonable assurance that adequate protective measures can and will be taken in the event of a radiological emergency Reasonable assurance finding is made before a nuclear facility is licensed Inspected over the lifetime of that facility 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

- Dwight D. Eisenhower

Emergency Planning:

• Reduces complex decision-making in an emergency

• Simplifies the choice of possible responses

• Allows for:

- Consistent and practiced approaches

- Addressing a spectrum of challenges irrespective of causes What should be used as a basis for EP?

In the 1970s, the Conference of Radiation Control Program Directors (CRCPD) 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 EP

The consequences from a spectrum of accidents, tempered by probability considerations, should be considered to scope the planning efforts for:

• The d i sta n ce to which planning for predetermined protective actions is warranted

• The time dependent characteristics of a potential release

• The type of radioactive materials

The planning basis included a recommended 10 mile plume exposure path emergency planning zone (EPZ) and a 50 mile ingestion pathway zone

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 EPZ 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 PA G for a prompt response PA R Protective Action Guide (PAG) PA D projected dose to an individual member of the public that warrants protective action

Protective Action Recommendation (PAR) PA G recommended protective measure from the nuclear power plant to offsite response PA DPA R organizations (OROs)

Protective Action Decision (PAD) measures taken in response to an actual or anticipated radiological release The EPZ is scalable

• 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 have 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. Fo r t h e wo rst-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

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 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 size 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 Shouldnt you be planning for the worst-case?

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)]

Capabilities are available at State and Federal level

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 ef fectively 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 Response capabilities are coordinated across levels

Licensee State 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 actions 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 Conservatively bounds 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 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-075/014 (WASH-1400), Reactor Safety Study: An Assessment of Accident Risks in U.S. Commercial Nuclear Power Plants, October 1975 Our understanding of accidents has evolved

NUREG/BR-0359, Revision 3, Modeling Potential Reactor Accident Consequences State-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 will continue to evolve Commission Policy Statement on Advanced Reactors

the Commission expects, as a minimum, at least the same degree of protection of the environment and public health and safety and the common defense and security that is required for current generation light-water reactors (LWRs)

The Commission also expects that advanced reactor designs will comply with the Commissions safety goal policy statement.

In addition, the Commission expects that the safety features of these advanced reactor designs will be complemented by the operational program for Emergency Planning (EP). This EP operational program, in turn, must be demonstrated by inspections, tests, analyses, and acceptance criteria to ensure effective implementation of established measures.

US NRC, Final Policy Statement: Policy Statement on the Regulation of Advanced Reactors, [NRC -2008- 0237];

73 FR 60612, October 14, 2008.

EP is a final, independent layer of defense in depth

DID is an approach to designing and operating nuclear facilities that prevents and mitigates accidents that release radiation or hazardous materials. Defense in depth includes the use of access controls, physical barriers, redundant and diverse key safety functions, and emergency response measures.

CAUTION! Some references do not clearly differentiate DID of design from siting and EP.1

NEI 18- 04, Rev. 1, Risk -Informed Performance-Based Technology Inclusive Guidance for Non-Light Water Reactor Licensing Basis Development August 2019.

IAEA approach provides similar considerations

IAEA. Addressing the issue of EPZ sizing for SMR, Technical Meeting on Challenges in the Application of the Design Safety Requirements for Nuclear Power Plants to Small and Medium Sized Reactors, September 4th, 2017 The planning basis informs EP planning functions Ensure capabilities exist to detect, classify, notify, assess, mitigate, and effectively respond to an emergency

Planning Basis Emergency Planning Needs and Functions Distance EPZ size, exposure pathways, protective Spectrum action strategies of Time Timeliness of classification and notification, protective action strategies, mitigation Accidents Detection and assessment capabilities, Materials radiological protection, mitigation Emergency preparedness is evidence-based

Protective Action Decisionmaking in the Intermediate Phase (NUREG/CR-7248)

Evacuation Time Estimate Study (NUREG/CR-7269)

Emergency Planning Zone (EPZ) Size Methodology Sensitivity of Dose Projections to Weather Analysis of the Effectiveness of Sheltering-in-Place Use of Heating and Ventilation Systems while Sheltering-in-Place Dose Reduction Effectiveness of Masks Nonradiological Health Impacts of Evacuations and Relocations (NUREG/CR-7285)

MACCS Consequence Model Improvements Impact on Protective Action Strategies Roles and Responsibilities

S tate / L o ca l FEMA - Technical N RC Review Hazards Division Set EP standards &

Responsible for emergency Reviews State and local reviews and approves planning and response for radiological emergency Review Findings licensee plans the community plans against planning Considers FEMA findings of Assess their own Assist standards offsite plans in reasonable capabilities and needs Can assist State & locals in assurance determinations Voluntarily participate in planning, if asked licensee planning NRC Licensee

Develops and maintains radiological emergency plans.

(NRC review and approval)

Examples of Risk-Informed Approaches to EP Regulatory Basis for Decommissioning Rule

The overall objective of EP is to provide dose savings for a spectrum of accidents that could produce offsite doses in excess of PAGs

EPZs are areas for which planning is needed to assure that prompt and effective actions can be taken to protect the public in the event of an accident

For a facility in decommissioning:

• The spectrum of accidents are significantly fewer than at an operating plant

• Design Basis Accidents will not exceed 1 rem offsite

• At least 10 hours1.157407e-4 days <br />0.00278 hours <br />1.653439e-5 weeks <br />3.805e-6 months <br /> available to mitigate or initiate protective actions Levels of Decommissioning Applying the planning basis to regulation

Proposed rule for power reactors based on the reduction in risk at four levels of decommissioning,

including the time when spent fuel has sufficiently decayed such that it would not reach self -ignition temperature in 10 hours1.157407e-4 days <br />0.00278 hours <br />1.653439e-5 weeks <br />3.805e-6 months <br /> under adiabatic heatup conditions

Initiating Event 10 hours1.157407e-4 days <br />0.00278 hours <br />1.653439e-5 weeks <br />3.805e-6 months <br /> Mitigate or (Severe Earthquake) Initiate Response

Time

Federal Register Notice Proposed Rule, Regulatory Improvements for Production and Utilization Facilities Transitioning to Decommissioning: Proposed Rule, 87 FR 12254 March 3, 2022 Conservatively assumes spent fuel pool damaged and drains instantaneously

NUREG-2161, Consequence Study of a Beyond -Design-Basis Earthquake Affecting the Spent Fuel Pool for a U.S.

Mark I Boiling Water Reactor, September 2014 Conservatively assumes unfavorable heat transfer

Transmittal of Reports to Inform Decommissioning Plant Rulemaking for User Need Request NSIR-2015- 001, dated May 31, 2016 (ADAMS Accession No. ML16110A416)

Conservatively assumes instantaneous release

Transmittal of Reports to Inform Decommissioning Plant Rulemaking for User Need Request NSIR-2015- 001, dated May 31, 2016 (ADAMS Accession No. ML16110A416)

Risk-informed regulations cover uncertainty

Proposed regulatory criteria

Minimum time margin: + 8.5 hr

Median time margin: + 24 hr

Realistic time margin: + days

10 hr Margin in 10 hr criteria Time Key Takeaways 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 Guidance and tools to support planning functions are informed by insights from PRAs EP is not based on risk or probability of an accident occurring Requires judgmentbacked by evidence