Sustaining Resilience of U.S. Nuclear Power Plants to

Extreme Events

Mike Franovich

Director (a), USNRC/JLD

March 27-29, 2017

Lessons Learned:

Near-Term Task Force

• Within weeks of the accident, USNRC created a task force to review the events and provide recommendations to enhance safety at U.S. plants

– Report issued July 2011

– Concluded that a similar sequence of events in the U.S. was unlikely and there were no imminent risks of continued operation and licensing activity

– Identified 12 overarching potential safety enhancements

2

USNRC Leadership

3

• Commission

• Steering Committee – Directorate/Division

– Three Tiers of Actions • (orders, RFI, rulemaking,

evaluations)

– Guiding Principles

– Senior Leadership Reflections – Visit to Japan

– Frequent engagement with U.S. industry leadership and other stakeholders

USNRC Orders and Request for Information

4

• Three Orders were issued – Mitigation strategies for beyond design basis

events

– Spent fuel pool level instrumentation

– Severe accident capable hardened vent for BWR Mark I and II containments

• Request for information was issued – Conduct walkdowns for seismic and flood

protection

– Reevaluate seismic and flood hazards using present day methods

– Evaluate emergency preparedness staffing and communications

Learning the Lessons

5

Continued Oversight of Safety Enhancements

Safety Evaluations and Verification of Compliance

Implementation with NRC-Endorsed Industry Guidance

Three Orders and Request for Information

Near-Term Task Force Report G

ain

ing

in

sig

hts

an

d e

nh

an

cin

g

ap

pro

ac

he

s

2011

Today

2012

Safety has been significantly improved

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Recommendation Status

Ensuring Protection

from External Events

2.1 – Reevaluation of seismic & flooding hazards Ongoing

2.2 – Periodic reconfirmation of hazards Assessment Complete

2.3 – Seismic & flooding hazard walkdowns Closed

Other – Reevaluate other external hazards Assessment Complete

Enhancing Mitigation of

Beyond-Design-Basis

Events

4.1 – Mitigation of beyond design basis events rulemaking* Draft Final Rule Complete

4.2 – Mitigation of beyond design basis events order Ongoing

5.1 – Severe accident capable hardened vents order Ongoing

5.2 – Vents for other containment designs Closed

6 – Hydrogen control and mitigation Closed

7.1 – Reliable spent fuel pool instrumentation Closed

7.2- 7.5 – Spent fuel pool water makeup capability* Draft Final Rule Complete

Strengthening

Emergency

Preparedness for Multi-

Unit Events

8.1-8.4 – Onsite emergency response capabilities* Draft Final Rule Complete

9.1-9.4 – Rulemaking to enhance emergency plans* Draft Final Rule Complete

10.1-10.2 – Analyze and evaluate other EP considerations* Draft Final Rule Complete

10.3 – Evaluate ERDS capabilities Closed

11.2&11.4 – Decision-making and public education Closed

Regulatory Philosophy 1 – Reassess regulatory framework Closed

12.1 – Include defense in depth requirements within ROP Closed

12.2 – Enhance staff training on severe accidents & SAMGs Closed

Radiological

Consequences

11.3 – Real time radiation monitoring within EPZ Assessment Complete

Other – Containment vent filters/filtering strategies Closed

Other – Expand EPZ size beyond 10 miles Closed

Other – Pre-stage KI to residents beyond 10 miles Closed

Other – Expedited transfer of spent fuel to dry storage Closed

*Integrated into MBDBE rulemaking

Activities substantially complete

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*For illustrative purposes only Today

Mitigating Strategies

Spent Fuel Pool Instrumentation

Hardened Vents

Walkdowns

Seismic Reevaluations

Flooding Reevaluations

Staffing & Communication

Mitigation of Beyond Design Basis Events

Containment Protection/Release

Reduction

Ord

ers 5

0.5

4(f) R

equ

ests R

ule-

makin

g

2012

85/99 units in compliance

Complete

Phase 1 and 2 ISEs complete

27/61 sites completed 2.1 response

Complete

Draft final rule delivered to Commission

2013 2014 2015 2016 2017 2018 2019 2020

Hazard acceptance letters issued

Complete

Closed

Tier 2&3 Resolution plans delivered to Commission

Mitigating Strategies

Requires a three-phase approach for maintaining or

restoring core cooling, containment, and spent fuel

cooling

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Phase

Licensee may use

Initial

Installed

equipment

Transition

Portable, onsite

equipment

Final Resources

obtained from offsite

+

+

Fundamental cornerstone of United States approach

Mitigating Strategies – What is FLEX?

• NEI 12-06 (Diverse and Flexible coping strategies (FLEX)

Implementation Guide)

– Endorsed by the USNRC August 2012 to support implementation

of Mitigating Strategies Order

– FLEX provides a means to prevent fuel damage while

maintaining containment function and spent fuel pool cooling

in beyond design basis external event conditions resulting in an: • Extended Loss of AC Power, and

• Loss of Normal Access to the Ultimate Heat Sink

9

Establishes an essentially indefinite coping

capability by relying upon installed equipment,

onsite portable equipment, and pre-staged

offsite resources

Mitigating strategies implementation

is nearing completion

• USNRC conducting

inspections confirming

order compliance

• No substantive

inspection findings to

date

• Transition to long-term

oversight plan 10

Working to expedite

BWR vent order closure • Applies to BWRs with certain

designs (Mark I/II)

• Vents help control pressure by

removing heat

• May help prevent core

damage

• Required to work when

normal power is lost

• Must continue to function if

core damage/melting occurs

• Developing inspection

procedure to confirm

compliance 11

• U.S. plants perform probabilistic

seismic hazard analyses following

USNRC guidance (RG 1.208)

• CEUS licensees (94 units/58 sites)

– Regional CEUS seismic source

– Regional CEUS ground motion

– Plant-specific site analyses

• Western licensees (6 units/3 sites)

– Regional source and ground

motion

models developed by each

licensee

– Plant-specific site analyses

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Development of Seismic Hazard

Seismic – High Frequency (example)

U.S. BWR site

(example)

• SSE ≥ GMRS for frequencies 1-10 Hz

• Above 10 Hz GMRS > SSE

13

Seismic hazard reevaluation

is on schedule

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Phase 2

Decisions

cost-benefit assessment

Hazard Acceptance

Review

(Complete)

Mitigation Strategies

Assessment

Interim Actions

(complete)

High-Frequency

Evaluation

Spent Fuel Pool

Evaluation

Seismic

Probabilistic

Risk Assessment

(18 sites – 2017-2019) Im

ple

me

nt G

uid

an

ce

Sa

fe

ty E

nh

anc

em

en

ts

Op Ex

Use SPRA technology where insights

would be most useful to safety

Leverage prior seismic risk or margins

studies (e.g., IPEEE)

Consider actual plant performance in

earthquakes – Kashiwazaki-Kariwa,

Onagawa, Fukushima, North Anna

Weigh outcomes against USNRC Safety

Goals, risk metrics

Reevaluated Flood Hazards

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Consider associated effects:

• Wind waves and run-up effects; • Hydrodynamic loading

(including debris); • Sediment deposition and

erosion;

• Concurrent site conditions; • Groundwater ingress; and

• Other pertinent factors.

Flooding action plan implementation

is on schedule Im

ple

me

nt G

uid

an

ce

Sa

fe

ty E

nh

anc

em

en

ts

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Phase 2

Decisions

cost-benefit assessment

Hazard Acceptance

Review

(Complete)

Mitigation Strategies

Assessments

Interim Actions

(Complete)

Focused Evaluations

(June 2017) Integrated

Assessments

(6 sites - 2018)

Op Ex

Advanced warning time for plant

preparedness and actions is a key

factor for realistic mitigation

strategies

Leverage insights from plant

walkdowns and inspections (wall

penetration seals installation &

integrity)

Mitigation of Beyond Design Basis Events Rule integrates the post-Fukushima efforts

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Performance-based regulation

enables innovative approaches

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• Performance-based approach and

broad view

• Captures mitigation strategies Order

• Requires reevaluated seismic and

flooding hazards be addressed

• Flexible scheduling option for plant

implementation

Rule establishes an integrated response capability

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• Assists operators in executing strategies

• Includes:

– Mitigation strategies (post-Fukushima)

– Reevaluated seismic and flooding

hazards

– Extensive damage mitigation guidelines

(post-9/11 strategies)

• Integration with emergency operating

procedures

Rule ensures equipment supports implementation of strategies

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• Capacity and capability

• Reasonable protection

• Communications capability

• Maintenance

Rule includes comprehensive approach to

organizational readiness/capability

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• Sufficient staffing

• Systems approach to training

• Periodic drills or exercises

• Ongoing feedback reflected in updates/revisions to

implementation guidance

• USNRC audits before compliance due dates helped

identified plant-specific and generic items to be

resolved

• Reevaluated seismic and flooding information

reflected in assessment of mitigating strategies

• Frequent interactions between USNRC and industry

• Rulemaking process is a systematic approach and

on a pace that allowed implementation operating

experience to be captured under performance

based and risk-informed requirements

Regulatory guidance incorporates operating experience

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Leveraging FLEX in safety and

security decision making

• Significant investment in equipment

and implementation

• Substantial risk benefits - Example areas:

• Enhancing safety to reduce risk during outages by

using FLEX as an additional layer of defense

• Using FLEX equipment as an additional layer of

defense when emergency equipment are taken

out-of-service while plants are at-power

• Modifying USNRC internal guidance

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Station blackout risk reduction

for a spectrum of hazards

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Post-Fukushima Improvements (Mitigation Strategies for ELAP)

SBO Rule (1989) Maintenance Rule (1996) – SSC reliability and availability

Risk Informed Licensing Actions(1990s - present)

Post-9/11 Requirements (B.5.b measures - 2006)

NFPA-805 Fire Protection Standard (2012 – present)

performance-based, risk-informed approaches

SB

O R

isk

Effective transition to ensure lasting benefit – challenges and opportunities

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• Considerable achievements to date

• Knowledge management effort underway to

sustain organizational competency

• Transition program to long-term inspection

and oversight under existing programs

• Reflect post-Fukushima improvements in

future risk-informed decisions

• Ongoing confirmation of natural hazards

– Potential enhancements to existing USNRC

internal processes

Independent Reviews

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• U.S. National Academy of Sciences

– Congressionally mandated study

completed

– Phase 1 Fukushima accident

– Phase 2 Spent fuel pool safety and

security

• Advisory Committee on Reactor

Safeguards

– Ongoing review of USNRC staff

actions

Summary

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• Considerable progress has been made

• Activities have already resulted in

safety improvements

• Additional information can be found

at:

https://www.nrc.gov/reactors/operating/o

ps-experience/japan-dashboard.html

Acronyms • CEUS – Central and Eastern United States

• ELAP – Extended Loss of Alternating-current Power

• FLEX – Diverse and Flexible coping strategies

• ISE – Interim Staff Evaluation

• LCF – Latent Cancer Fatality

• IPEEE – Individual Plant Examination of External Events

• MBDBE – Mitigation of Beyond Design Basis Events

• NEI – Nuclear Energy Institute

• NFPA – National Fire Protection Association

• Op Ex – Operating Experience

• QHO – Quantitative Health Objective

• RFI – Request for Information

• SBO – Station Blackout

• SFP – Spent Fuel Pool

• SPRA – Seismic Probabilistic Risk Assessment

• SSC – Structure, System, or Component

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Backup Slides

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Spent Fuel Pool Instrumentation

• Order requires

installation of water level

instrumentation to

indicate the certain

levels

• Milestones: – Order issued in 2012

– Review and schedule

merged with Mitigating

Strategies

30

BWR CPRR Regulatory Analysis Comparison to NRC Safety Goal

• Frequency-weighted

individual LCF risk is

orders of magnitude

below the NRC Safety

Goal QHO

• High-level conservative

estimate using highest

ELAP frequency and

highest conditional LCF

risk about 30 times below

QHO

• Risk reduction from

regulatory alternatives

are within uncertainty

bounds

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