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BgNS International Conference “ NUCLEAR POWER FOR THE PEOPLE”

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”

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  1. 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

  2. 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

  3. 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

  4. “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

  5. “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

  6. “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

  7. “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

  8. “LE BLAYAIS” NPP FLOODING in 1999 PROBLEMS IDENTIFIED DURING « LE BLAYAIS » FLOODING BgNS International Conference - 26–29 September 2010,Nesebar, Bulgaria

  9. “LE BLAYAIS” NPP FLOODING FOLLOWS-UP OVERVIEW OF « LE BLAYAIS » FLOODING FOLLOWS-UP BgNS International Conference - 26–29 September 2010,Nesebar, Bulgaria

  10. 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

  11. (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

  12. 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

  13. 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

  14. 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

  15. 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

  16. 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

  17. 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

  18. 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

  19. 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

  20. 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

  21. 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

  22. 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

  23. 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

  24. 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

  25. 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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