Sustaining Resilience of U.S. Nuclear Power Plants to ... . Nuclear Power Plants to Extreme Events Mike Franovich Director (a), ... 2.3 – Seismic ... •Systems approach to training

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  • 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

    6

    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

    7

    *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

    8

    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

    12

    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

    14

    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

    15

    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

    16

    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

    17

  • Performance-based regulation

    enables innovative approaches

    18

    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

    19

    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

    20

    Capacity and capability

    Reasonable protection

    Communications capability

    Maintenance

  • Rule includes comprehensive approach to

    organizational readiness/capability

    21

    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

    22

  • 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

    23

  • Station blackout risk reduction

    for a spectrum of hazards

    24

    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

    25

    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

    26

    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

    27

    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

    https://www.nrc.gov/reactors/operating/ops-experience/japan-dashboard.htmlhttps://www.nrc.gov/reactors/operating/ops-experience/japan-dashboard.htmlhttps://www.nrc.gov/reactors/operating/ops-experience/japan-dashboard.htmlhttps://www.nrc.gov/reactors/operating/ops-experience/japan-dashboard.htmlhttps://www.nrc.gov/reactors/operating/ops-experience/japan-dashboard.htmlhttps://www.nrc.gov/reactors/operating/ops-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

    28

  • 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

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