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BgNS International Conference “ NUCLEAR POWER FOR THE PEOPLE” 26 – 29 September 2010, Nesebar, Bulgaria. From the “Le Blayais NPP” flooding in 1999 to the review of French regulation for the protection of nuclear installations against external flooding. By Patricia DUPUY, IRSN. INTRODUCTION.

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Bgns international conference nuclear power for the people 26 29 september 2010 nesebar bulgaria

BgNS International Conference “NUCLEAR POWER FOR THE PEOPLE”

26 – 29 September 2010,Nesebar, Bulgaria

From the “Le Blayais NPP” flooding in 1999to the review of French regulationfor the protection of nuclear installations against external flooding

By Patricia DUPUY, IRSN


Introduction

INTRODUCTION

INTRODUCTION

  • Flooding event at “Le Blayais” NPP in 1999

    • Description, lessons learned

  • “Le Blayais” flooding follows-up

    • Review of the protection of all operating NPPs against external flooding

    • Review of French regulation: preparation of a “Guide” on external flooding

  • Conclusion

BgNS International Conference - 26–29 September 2010,Nesebar, Bulgaria


FRENCH CONTEXT – NPPs LOCATION

NPPs location:

  • 14 river NPPs

  • 4 coastal NPPs

  • 1 estuarine NPP

  • A single utility: EDF (Electricité de France)

  • NPPs

    BgNS International Conference - 26–29 September 2010,Nesebar, Bulgaria


    “LE BLAYAIS” NPP FLOODING in 1999

    High water level (high tide + storm surge) + waves (generated by the wind) in the estuary

    • Important water volumes over the dykes

    • Site and buildings flooding

    Nuclear island

    Safety Eqpts

    1999 Storm

    « Le Blayais » NPP partial flooding

    BgNS International Conference - 26–29 September 2010,Nesebar, Bulgaria


    Description of the flooding event 1 3

    “LE BLAYAIS” NPP FLOODING in 1999

    Water ingress in trenches through unleaktigh metalic plates

    Water ingress in trenches through concrete panels

    Water ingress from surrounding flooded swamp through an access road

    DESCRIPTION OF THE FLOODING EVENT (1/3)

    Dykes

    Waves

    BgNS International Conference - 26–29 September 2010,Nesebar, Bulgaria


    “LE BLAYAIS” NPP FLOODING in 1999

    Damaged electrical penetration in the unit 1 Fuel Building basement

    Fire door burst open

    To unit 2

    Galleries flooded

    Some rooms flooded into the « pumping station » building

    Water ingress through pipes penetrations into the Fuel building basements

    DESCRIPTION OF THE FLOODING EVENT (2/3)

    • Water progression in Unit 1


    “LE BLAYAIS” NPP FLOODING in 1999

    DESCRIPTION OF THE FLOODING EVENT (3/3)

    1

    2

    STATE OF UNITS 1-2 AFTER FLOODING

    Pumping station

    • Some components of safety systems flooded in units 1&2

    • 2 essential service water pumps of train A (unit 1)

    • 2 low head safety inject. pumps and 2 containment spray pumps (units 1&2)

    • Not much water in units 3&4


    Problems identified during le blayais flooding

    “LE BLAYAIS” NPP FLOODING in 1999

    PROBLEMS IDENTIFIED DURING « LE BLAYAIS » FLOODING

    BgNS International Conference - 26–29 September 2010,Nesebar, Bulgaria


    Overview of le blayais flooding follows up

    “LE BLAYAIS” NPP FLOODING FOLLOWS-UP

    OVERVIEW OF « LE BLAYAIS » FLOODING FOLLOWS-UP

    BgNS International Conference - 26–29 September 2010,Nesebar, Bulgaria


    REVIEW OF THE PROTECTION OF NPPs AGAINST EXTERNAL FLOODING

    REVIEW OF THE PROTECTION OF EXISTING NPPsAGAINST EXTERNAL FLOODING: METHODOLOGY

    BgNS International Conference - 26–29 September 2010,Nesebar, Bulgaria


    (1) (2)

    (3) (4) (5)

    Prior to “Le Blayais” event : Basic Safety Rule (BSR)

    that defines requirements for river/estuary/marine water levels to consider in the design of French NPP (DBF)

    (1) River flood, (2) Dam failure, (3) Tide, (4) Storm surge and (5) Tsunami

    Floodinghazards

    Atmosphere

    Water retaining structures Canal

    Water retaining

    structures

    Circuits Equipments

    River Estuary Sea

    Groundwater

    BgNS International Conference - 26–29 September 2010,Nesebar, Bulgaria


    Floodinghazards

    Atmosphere

    Water retaining structures Canal

    (11)

    (12)

    Water retaining

    structures

    (8)

    (7)

    Circuits Equipments

    (1) (2)

    (3) (4) (5)

    River Estuary Sea

    (9)

    (10)

    (9)

    (8)

    (6) (7)

    (13)

    Groundwater

    New methodology: 8 “complementary” phenomena

    (6) Wind-waves on sea (7) Wind-waves on river or channel

    (8) Swelling due to operation on valves or pumps

    (9) Water retaining structures (other than dams) deterioration

    (10) Circuits or equipments failure

    (11) Rainfalls on site, brief and intense (12) Rainfalls on site, regular and continuous

    (13) Groundwater rising

    + some combinations of phenomena considered

    BgNS International Conference - 26–29 September 2010,Nesebar, Bulgaria


    REVIEW OF THE PROTECTION OF NPPs AGAINST EXTERNAL FLOODING

    Site protection

    Protection structures/devices reviewed: type, height, margins, settling, stability, safety classification, seismic resistance, power-supply, maintenance …

    Protection means

     Modifications/Improvements at many sites (dykes/walls raised or extended or reinforced…)

    Some examples

    Le Blayais dykes

    Protection against swelling (canal)

    BgNS International Conference - 26–29 September 2010,Nesebar, Bulgaria


    REVIEW OF THE PROTECTION OF NPPs AGAINST EXTERNAL FLOODING

    At all NPPs, including the substructures of the buildings sheltering equipments to be protected

    Depending on the sites vulnerabilities, including superstructures up to the required protection level

    Protection of sensitive rooms/equipments(1/2)

    Protection means

     Definition of a compact “watertight area”

    Additional flood hazards (rainfalls, groundwater rising…)

    Water level

    BgNS International Conference - 26–29 September 2010,Nesebar, Bulgaria


    REVIEW OF THE PROTECTION OF NPPs AGAINST EXTERNAL FLOODING

    Protection of sensitive rooms/equipments(2/2)

    • + Provisions to prevent water ingress into the watertight area:

      • Water paths plugged with qualified material

      • Provisions to close potential ways of bypassing quickly if opened

      • Mobile pumps and detection means in case of residual leakage

      • . . .

    Protection means

    EX: Qualified material to plug the waterpaths and penetrations

    BgNS International Conference - 26–29 September 2010,Nesebar, Bulgaria


    REVIEW OF THE PROTECTION OF NPPs AGAINST EXTERNAL FLOODING

    Stand-by phase

    Vigilance phase (early actions)

    T0–24h

    Early warning phase (site protection preparedness)

    T0–12h

    T0

    Alert phase ( safe state)

    Warning system, « flooding » procedure

    Protection means

    Warning systems for predictable hazards: graduated phases

    depending on site vulnerabilities

    Warning system associated to a “flooding” procedure, to prepare the site protection during the warning phases

    BgNS International Conference - 26–29 September 2010,Nesebar, Bulgaria


    REVIEW OF THE PROTECTION OF NPPs AGAINST EXTERNAL FLOODING

    Analysis of the flooding effects

     provisions to cope with them

    • Examples:

    • Modifications to avoid flooding of sensitive switchyards components

    • Adaptation of the on-site emergency organization:

      • All units might be affected and require staff/material resources

      • The site might be “isolated”

    Flooding effects on NPP’s support functions and surroundings

    Early warning phase on-site emergency team

    Alert phase  national emergency organization activated

    End 2003 « La Loire » flood

    BgNS International Conference - 26–29 September 2010,Nesebar, Bulgaria


    Review of the protection of npps against external flooding

    REVIEW OF THE PROTECTION OF NPPs AGAINST EXTERNAL FLOODING

    1999Le Blayais flooding

    New methodology« REX Blayais » defined by the utility, analyzed by IRSN

    End 2001Advisory Committee

    2007Advisory Committee

    Level of protection of the 19 NPP sites against external flooding globally satisfactorySome modifications and issues to be finalized

    New methodology globally approved by the safety authoritySome methodological points to be enhanced

    REVIEW OF THE PROTECTION OF NPPs AGAINST EXTERNAL FLOODING

    Complementarymethodologicalaspects+ Application to the 19 NPPs Sites

    BgNS International Conference - 26–29 September 2010,Nesebar, Bulgaria


    Future french guide

    FUTURE FRENCH GUIDE

    FUTURE FRENCH GUIDE

    « Le Blayais » flooding has calledinto question the design bases for the protection againstexternalflooding (Basic SafetyRule I.2.e)

    Update of BSR I.2.e required by the Safety Authority: replacement of the BSR by a Guide

    2006-2009: Working Group for preparation of a draft Guide

    • Directed by the Nuclear Safety Authority and IRSN

    • With representatives of:

      • Nuclear utilities

      • Qualified experts (hydrology, hydraulics and meteorology)

    BgNS International Conference - 26–29 September 2010,Nesebar, Bulgaria


    Future guide applicable to

    FUTURE FRENCH GUIDE

    FUTURE GUIDE APPLICABLE TO:

    • Nuclear power plants (NPPs)

    • All other surface nuclear installations

      • No safety rule related to their protection against external flooding

      • Need for more consistency with the approach for NPPs

      • Impact of “Le Rhône” River flood on nuclear facilities in 2003

    • Guide applicable first to future installations

    BgNS International Conference - 26–29 September 2010,Nesebar, Bulgaria


    FUTURE FRENCH GUIDE

    THE FUTURE GUIDE DEALS WITH:

    • Identification of phenomenathat can lead to site flooding

    • Definition of “Reference Flooding Situations (RFS)”

      • For each phenomena, RFS = the minimum hazard level to be considered in the design of future installations

    • Methods for the characterization of the RFS

      • Mostly based on REX Blayais methodology but some differences

    • Principles for protection of the installations

      • Good practices, relying on Le Blayais flooding to a large extent

    BgNS International Conference - 26–29 September 2010,Nesebar, Bulgaria


    Future guide some principles

    FUTURE FRENCH GUIDE

    FUTURE GUIDE: SOME PRINCIPLES

    • Intended “target” for the definition of RFS(not explicitly mentioned in the Guide): return period of 10 000 years

      • In several cases, difficulties to reach the target

    • All nuclear surface installations must cope with the same RFS

    • The level of protection and the margins depend on:

      • The type of installation and the flooding consequences on safety

      • The general safety goals assigned to the installation

      • The potential “cliff-edge” effect of a situation of higher intensity

        • Margins might be required for new reactors

    • Successive lines of defense recommended (as possible) to protect:

      • Buildings housing systems/components involved in safety functions

      • Rooms inside the buildings

      • Safety systems and components themselves

    BgNS International Conference - 26–29 September 2010,Nesebar, Bulgaria


    From le blayais npp flooding event to the revision of the basic safety rule
    From Le Blayais NPP flooding event… …to the revision of the Basic Safety Rule

    End 2001Advisory Committee

    2007Advisory Committee

    Level of protection of the 19 NPP sites against external flooding globally satisfactorySome aspects to be enhanced or finalized

    New methodology globally approved by the safety authoritySome methodological points to be enhanced

    1999Le Blayais flooding

    New methodology« REX Blayais »defined by the utility, analyzed by IRSN

    Complementarymethodologicalaspects+ Application to the 19 NPPs Sites

    BgNS International Conference - 26–29 September 2010,Nesebar, Bulgaria


    From le blayais npp flooding event to the revision of the basic safety rule1
    From Le Blayais NPP flooding event… …to the revision of the Basic Safety Rule

    2011Advisory Committee

    Consultation

    of Operators

    & General Public

    Adaptation

    of the Guide

    End 2009

    Working Group on Guide (2006)

    2011/2012

    Guide

    Draft Guide

    Advisory commitee comments

    Working Group

    Hazards

    & Protections

    BgNS International Conference - 26–29 September 2010,Nesebar, Bulgaria


    Conclusion
    CONCLUSION

    Following the partial flooding of « Le Blayais » NPP in 1999:

    Design bases used for the protection of NPPs and existing measures called into question

    Comprehensive reassessment of the protection of all French NPPs against external flooding and to a large number of modifications and improvements

    Update of the French requirements and submission of a draft Guide on the protection of all nuclear surface installations against external flooding Guide expected 2011/2012

    BgNS International Conference - 26–29 September 2010,Nesebar, Bulgaria


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