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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

slide3

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

slide4

“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

slide6

“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
slide7

“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

slide10

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

slide11

(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

slide12

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

slide13

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

slide14

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

slide15

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

slide16

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

slide17

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

slide21

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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