FRENCH PWR’S ULTIMATE HEAT SINKS THREATENED BY THEIR ENVIRONMENT “Nuclear power for the people” Nesebar, 26-29 September, 2010 Véronique BERTRAND IRSN, France Système de management de la qualité IRSN certifié

SUMMARY Heat sink: generalities Total loss of heat sink at Cruas unit 4 in December 2009 Total loss of heat sink management from the initial design EPR Flamanville 3 pumping station’s design Conclusion Nuclear power for the people – 26-29 September, 2010 – Nesebar, Bulgaria – Page 2

FRENCH NPPs IMPLANTATION Heat sink - generalities FRENCH NPPs IMPLANTATION 58 reactors in operation (+1 under construction–EPR at Flamanville) 19 sites :  4 coastal Flamanville (2×1300 MWe) Paluel (4×1300 MWe) Penly (2×1300 MWe) Gravelines (6×900 MWe)  1 estuarine Blayais (4×900 MWe)  14 riverside (including 11 with cooling towers) Nuclear power for the people – 26-29 September, 2010 – Nesebar, Bulgaria – Page 3

Heat sink - generalities Pre-filtration and filtration in the pumping station 2 circuits supplied ensuring the reactor’s cooling Cooling circuit of the nuclear island including safety systems called Essential Service Water System (ESWS) Cooling circuit of the conventional island Conventional island Role of the cooling circuit The cooling circuit of the conventional island isn’t a system important to safety Nuclear power for the people – 26-29 September, 2010 – Nesebar, Bulgaria – Page 4

Conventional heat sink Heat sink - generalities REACTORS COOLING: CASE WITH COOLING TOWER CONVENTIONAL ISLAND ALTERNATOR TURBINE HEATER CONDENSER MSS AFS FFCS CSS RHRS Conventional heat sink NUCLEAR ISLAND SIS COOLING TOWER Reactor coolant system CCWS Safety heat sink ESWS Nuclear power for the people – 26-29 September, 2010 – Nesebar, Bulgaria – Page 5

REACTORS COOLING: A SAFETY FUNCTION Heat sink - generalities REACTORS COOLING: A SAFETY FUNCTION ESWS: cooling of an intermediate cooling system, the Component Cooling Water System (CCWS) ESWS and CCWS are systems important to safety ESWS: two redundant trains CCWS responsible for cooling of safety equipment Nuclear power for the people – 26-29 September, 2010 – Nesebar, Bulgaria – Page 6

PROTECTION AGAINST EXTERNAL HAZARDS Heat sink - generalities PROTECTION AGAINST EXTERNAL HAZARDS External hazards considered from the initial design earthquakes external flooding cold weather snow extreme wind other phenomena External hazards underestimated freezing frazil ice high air temperatures seaweed vegetable matter external flooding with or without extreme wind Nuclear power for the people – 26-29 September, 2010 – Nesebar, Bulgaria – Page 7

TOTAL LOSS OF HEAT SINK AT CRUAS 4 IN DECEMBER 2009 Expérience feedback in 2009 TOTAL LOSS OF HEAT SINK AT CRUAS 4 IN DECEMBER 2009 CRUAS NPP (900 MWe): 4 units Date of the incident: 1st December, 2009 Rated level 2 on the INES scale Nuclear power for the people – 26-29 September, 2010 – Nesebar, Bulgaria – Page 8

Total loss of heat sink at Cruas 4 in December 2009 Nuclear power for the people – 26-29 September, 2010 – Nesebar, Bulgaria – Page 9

Total loss of heat sink at Cruas 4 in December 2009 Train B Unit 1 Unit 2 Train A B Unit 4 Unit 3 Navigation Channel River Rhône Discharge basin Discharge ducts B1 A1 A2 B2 B3 B4 A3 A4 Intake channel Rhône river bed Floating dyke ESWS Galleries trains A & B of unit 1 trains A & B of unit 4 Intake coarse filtration & trash removal system (1 grid/train) – units 1&2 CCWS Building units 3&4 Nuclear power for the people – 26-29 September, 2010 – Nesebar, Bulgaria – Page 10

Total loss of heat sink at Cruas 4 in December 2009 Nuclear power for the people – 26-29 September, 2010 – Nesebar, Bulgaria – Page 11

WHAT HAPPENED ? Total loss of heat sink at Cruas 4 in December 2009 01/12/2009 : massive unprecedented blockage ESWS train A unavailable Reactor 4 shutdown ESWS train B unavailable Unit 4: total loss of heat sink  the first time in France concerning a PWR National Crisis Organization activated French public authorities (ASN) Technical support (IRSN) French utility (EDF) Nuclear power for the people – 26-29 September, 2010 – Nesebar, Bulgaria – Page 12

Total loss of heat sink at Cruas 4 in December 2009 Application of the Emergency Operating Procedures (EOPs) Difficulties in the procedure Unit 4 in a safe state 3 hours later Use of the thermal inertia of the refuelling water storage tank (RWST) reserve Efficient cleaning of filtration device and ESWS/CCWS exchangers Total loss of heat sink lasted 10 hours Units 2&3 partially lost heat sink Nuclear power for the people – 26-29 September, 2010 – Nesebar, Bulgaria – Page 13

Canadian pondweed plants Total loss of heat sink at Cruas 4 in December 2009 Canadian pondweed plants Nuclear power for the people – 26-29 September, 2010 – Nesebar, Bulgaria – Page 14

 IRSN started an in-depth analysis of this incident Total loss of heat sink at Cruas 4 in December 2009 LESSONS LEARNT First ever occurrence on a PWR in France Partial loss of heat sink on units 2 and 3 together with the total loss on unit 4 Efficient management needs quick and reliable diagnosis of the situation and mitigation means Need to improve the emergency procedure Use of thermal inertia of RWST water proved to be effective On-site trash rack pre-filtration cleaning devices proved to be insufficient  IRSN started an in-depth analysis of this incident Nuclear power for the people – 26-29 September, 2010 – Nesebar, Bulgaria – Page 15

OTHER EVENTS Experience feedback in 2009 Frazil ice event at Chooz B NPP in January Vegetable matter ingress in Le Blayais NPP, February and March Drum screens clogging at Fessenheim NPP in December Nuclear power for the people – 26-29 September, 2010 – Nesebar, Bulgaria – Page 16

CONSEQUENCES Experience feedback in 2009 Action plan from the utility EDF Heat sink operating conditions and design Operating procedures Criteria for emergency organization activation IRSN analysis Characterisation of hazards Monitoring and protection of the pumping station Existing means, procedures, organization Nuclear power for the people – 26-29 September, 2010 – Nesebar, Bulgaria – Page 17

TOTAL LOSS OF HEAT SINK MANAGEMENT FROM THE INITIAL DESIGN Incident procedure evolution Probabilistic safety assessment (PSA) contribution Loss of heat sink on all units of a NPP Nuclear power for the people – 26-29 September, 2010 – Nesebar, Bulgaria – Page 18

INCIDENT PROCEDURE EVOLUTION Total loss of heat sink management from the initial design of French NPPs INCIDENT PROCEDURE EVOLUTION Use of the thermal inertia of the refuelling water storage tank (RWST) reserve Emergency heat sink for cooling temporarily the component cooling water system (CCWS) Throughout a containment spray system (CSS) heat exchanger Foreseen enhancement: operation of one reactor cooling pump and one charging pump Nuclear power for the people – 26-29 September, 2010 – Nesebar, Bulgaria – Page 19

PROBABILISTIC SAFETY ASSESSMENT (PSA) CONTRIBUTION Total loss of heat sink management from the initial design of French NPPs PROBABILISTIC SAFETY ASSESSMENT (PSA) CONTRIBUTION PSA for PWR 900 MWe developed at IRSN Potential scenarios resulting from a total loss of ultimate heat sink with a high frequency Beyond the initial design Implementation of modifications Automatic disconnection of the reactor coolant letdown line Nuclear power for the people – 26-29 September, 2010 – Nesebar, Bulgaria – Page 20

LOSS OF HEAT SINK ON ALL UNITS OF A NPP Total loss of heat sink management from the initial design of French NPPs LOSS OF HEAT SINK ON ALL UNITS OF A NPP Recently subject to particular attention in France Wide study following the partial flooding of Le Blayais NPP Analysis of the guaranteed available on-site resources Modifications: sufficient required capacities of steam generator water supply Equivalent program for next safety reviews of other series Nuclear power for the people – 26-29 September, 2010 – Nesebar, Bulgaria – Page 21

EPR Flamanville 3 pumping station’s design Nuclear power for the people – 26-29 September, 2010 – Nesebar, Bulgaria – Page 22

EPR Flamanville 3 pumping station’s design Improvement of the pumping station’s initial design Four independent water trains Two diversified types of filtration devices with screens and chain filters Strengthening of the cleaning means of pre-filtration and filtration devices Enhanced reliability of head loss measurements to pre- filtration trash racks and filters New system: the ultimate cooling water system (UCWS) Foreseen for cooling an intermediate cooling system, which in turn cools The containment heat removal system (CHRS) The fuel pool cooling system (FPCS) third train Normal supply for ESWS and UCWS: pumping station Diversified cooling source: connexion to the outfall structure Nuclear power for the people – 26-29 September, 2010 – Nesebar, Bulgaria – Page 23

CONCLUSION Environmental conditions can impact the safety of nuclear reactors  Come back to the initial design 3 lines of defence Prevention: identification and knowledge of hazards  Appropriate design equipment Pumping station: monitoring, detection and protection means  To ensure a permanent ESWS flow rate Management of a total loss of heat sink  To cool the reactor until the heat sink recovery Expectation for EPR Flamanville 3 pumping station: to cope with external hazards Nuclear power for the people – 26-29 September, 2010 – Nesebar, Bulgaria – Page 24

THANK YOU FOR YOUR ATTENTION Nuclear power for the people – 26-29 September, 2010 – Nesebar, Bulgaria – Page 25