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
• 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
3
USNRC Orders and
Request for Information
• 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
4
2011
2012
Today
Gaining insights and enhancing
approaches
Learning the Lessons
Near-Term Task Force Report
Three Orders and Request for Information
Implementation with NRC-Endorsed Industry Guidance
Safety Evaluations and Verification of Compliance
Continued Oversight of Safety Enhancements
5
Safety has been significantly
improved
Recommendation
Ongoing
2.1 – Reevaluation of seismic & flooding hazards
Assessment Complete
2.2 – Periodic reconfirmation of hazards
Closed
2.3 – Seismic & flooding hazard walkdowns
Assessment Complete
Other – Reevaluate other external hazards
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
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

Ensuring Protection
from External Events

Enhancing Mitigation of
Beyond-Design-Basis
Events



Strengthening
Emergency
10.1-10.2 – Analyze and evaluate other EP considerations*
Preparedness for Multi- 10.3 – Evaluate ERDS capabilities
Unit Events
11.2&11.4 – Decision-making and public education
Regulatory Philosophy
Radiological
Consequences
Status
1 – Reassess regulatory framework
12.1 – Include defense in depth requirements within ROP
12.2 – Enhance staff training on severe accidents & SAMGs
11.3 – Real time radiation monitoring within EPZ
Other – Containment vent filters/filtering strategies
Other – Expand EPZ size beyond 10 miles
Other – Pre-stage KI to residents beyond 10 miles
Other – Expedited transfer of spent fuel to dry storage
Draft Final Rule Complete
Closed
Closed
Closed
Closed
Closed
Assessment Complete
Closed
Closed
Closed
Closed
*Integrated into MBDBE rulemaking
6
Activities substantially complete
2012
Mitigating
Strategies
Flooding
Reevaluations
Staffing &
Communication
Containment
Protection/Release
Reduction
Tier 2&3
27/61 sites completed 2.1 response
Hazard acceptance letters issued
Complete
Rulemaking
Mitigation of Beyond
Design Basis Events
Complete
50.54(f) Requests
Seismic
Reevaluations
Complete
Phase 1 and 2 ISEs complete
Hardened Vents
Walkdowns
2016 2017 2018 2019 2020
85/99 units in compliance
Orders
Spent Fuel Pool
Instrumentation
2013 2014 2015
Draft final rule delivered to Commission
Closed
Resolution plans delivered to Commission
Today
7
*For illustrative purposes only
Mitigating Strategies
Requires a three-phase approach for maintaining or
restoring core cooling, containment, and spent fuel
cooling
Phase
Licensee may use
Initial
Installed
equipment
Transition
+
Final
Resources
+obtained
from
Portable, onsite
equipment
offsite
Fundamental cornerstone of United States approach
8
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
Establishes an essentially indefinite coping
capability by relying upon installed equipment,
onsite portable equipment, and pre-staged
offsite resources
9
Mitigating strategies implementation
is nearing completion
• USNRC conducting
inspections confirming
order compliance
• No substantive
inspection findings to
date
• Transition to long-term
oversight plan
1
0
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
1
1
Development of Seismic Hazard
• 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
12
Seismic – High Frequency (example)
• SSE ≥ GMRS for frequencies 1-10 Hz
• Above 10 Hz GMRS > SSE
U.S. BWR site
(example)
13
Seismic hazard reevaluation
is on schedule
(Complete)
Interim Actions
(complete)
Mitigation Strategies
Assessment
High-Frequency
Evaluation
Spent Fuel Pool
Evaluation
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
Seismic
Probabilistic
Risk Assessment
(18 sites – 2017-2019)
Safety Enhancements
Implement Guidance
Hazard Acceptance
Review
Phase 2
Decisions
cost-benefit assessment
14
Reevaluated Flood Hazards
Consider associated effects:
• Wind waves and run-up effects; • Concurrent site conditions;
• Hydrodynamic loading
• Groundwater ingress; and
(including debris);
• Other pertinent factors.
• Sediment deposition and
erosion;
1
5
Implement Guidance
Hazard Acceptance
Review
(Complete)
Interim Actions
(Complete)
Focused Evaluations
(June 2017)
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 Strategies
Assessments
Integrated
Assessments
(6 sites - 2018)
Safety Enhancements
Flooding action plan implementation
is on schedule
Phase 2
Decisions
cost-benefit assessment
16
Mitigation of Beyond Design Basis Events
Rule integrates the post-Fukushima efforts
1
7
Performance-based regulation
enables innovative approaches
• Performance-based approach and
broad view
• Captures mitigation strategies Order
• Requires reevaluated seismic and
flooding hazards be addressed
• Flexible scheduling option for plant
implementation
1
8
Rule establishes an integrated
response capability
• 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
1
9
Rule ensures equipment supports
implementation of strategies
•
•
•
•
Capacity and capability
Reasonable protection
Communications capability
Maintenance
2
0
Rule includes comprehensive approach to
organizational readiness/capability
• Sufficient staffing
• Systems approach to training
• Periodic drills or exercises
2
1
Regulatory guidance incorporates
operating experience
• 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
2
2
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
2
3
Station blackout risk reduction
for a spectrum of hazards
SBO Rule (1989)
Maintenance Rule
(1996) – SSC reliability
and availability
Post-9/11 Requirements
(B.5.b measures - 2006)
SBO Risk
Risk Informed Licensing
Actions(1990s - present)
NFPA-805 Fire Protection
Standard (2012 – present)
Post-Fukushima Improvements
(Mitigation Strategies for ELAP)
performance-based, risk-informed approaches
2
4
Effective transition to ensure lasting benefit
– challenges and opportunities
• 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
2
5
Independent Reviews
• 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
2
6
Summary
• 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
2
7
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
2
8
Backup Slides
29
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
31