In-Service Inspection &Repair of Sodium Cooled Reactors General strategy and feedback experience

1. In-Service Inspection &Repair of Sodium Cooled Reactors General strategy and feedback experience F. Baqué DEN Cadarache

2. Objective Underlining the ISI&R aspect of sodium cooled reactors : In service inspection plan must be defined • Definition of ISI as Design confirmation tool Checking damage evolution of structures : - cracks absence or sizing - failure and component position detection - migrant piece detection - corrosion and tightness checking - buckling, creep effects, mesalignment

3. Background French and international feedback experience of existing sodium cooled Fast Reactors (mainly Phénix and Superphénix Plants, but also Monju) Secondary circuits & components Control rods / assemblies alignment Above core structure Component skirts Main and guard vessels Core supporting structures (diagrid…) Pump to diagrid pipe

4. Background Studies for innovative projects (mainly EFR, but also ALMR, DFBR, BREST-300) Russia USA

5. ISI&R parameters • Available ISI&R tools & techniques: • ISI : US, EMAT, visual … waiting for under sodium telemetry and NDT ? • Repair : sodium sweeping, cutting, TIG welding, laser… • Design simplicity as regards ISI&R needs: • Simple shapes for access to sensitive zones • Low stress, design margins to lower damage • Few and shorter welding joints to be inspected • Access facility to internal structures and components : • Specific channels • Removable parts

6. ISI&R parameters (continued) • Reactor size : • « the larger, deeper, longer it is, the harder ISI&R » • Structure characteristics : • Geometry (length, diameter, thickness…) • Material (laminated/forged, sensitivity to cracking, wetting) • Modularity : • Operating when a module is in shut down conditions for inspection and/or repair • Easily removable parts : • for easier and full inspection and/or repair • Reactor conditions : • Temperature, aerosols, radiation, air ingress risk…

7. ISI parameters : application to EFR project

8. Low inspection Large inspection Medium inspection hight Seriousness of damage for safety medium No inspection low medium hight low Cumulated potential damages ISI codes and standards • The « potential damage method » : for each structure • Limited to ASME section XI division 3

9. Low inspection Large inspection Medium inspection No inspection Cumulated damage Real damage Estimated damage Initial damage Time ISI codes and standards • « potential damage method » : • Initiated at the design phase • calculation of damages • evaluation of failure effects • Revised along plant life (all situation counting)

10. Potential damage method : application to Superphénix

11. More detailed ISI&R requirements Identification of priorities and recommendations SFR consistent design ISI at the Design phase • An iterative process : 1 Preliminary ISI evaluation of SFR concept 2 3 4

12. ISI&R criteria at Design stage : Proposal for ISI&R criteria utilization at Design stage

13. ISI&R criteria at Design stage : • Very important : • Tools & techniques + + + • Design simplicity o + + • Access facility o + + duration means quality • Less important : • Reactor size o + o • Structure characteristics + - - • Not so important : • Modularity o - - • Easily removable parts o o o • Reactor conditions o - -

14. Inspection of gas coverture :visual control above sodium free level Phenix primary vessel inspection : visual checking after partial primary sodium draining • In sodium qualification tests

15. R&D for the Inspection of immersed structures :in sodium ultrasonic telemetryin water qualification

16. Inspection of core supporting structures :Phénix experience • Ultrasonic inspection of 4.5 m long shell (immersed in sodium)

17. Repair of removable componants :handling out of primary vessel Handling of the drilling machine for Superphénix core catcher piercing : • mechanical process • 20 m long machine • Through roof penetration • Under sodium operation • 3 year developt & qualification

18. Primary vessel US sensors 700 mm 2 cameras Guard vessel In-Service Inspection of Superphénix PlantPrimary Vessel Welds : the Rapid Inspection Machine (MIR)

19. Leak zone Repair of immersed structures :Superphénix experience Repair of IHX argon feeding tube (1995)

20. Core outlet sodium behaviour :Superphénix acoustic monitoring 6 metallic bars within above core structure Argon in primary sodium Control rod impact

21. Tube bundle inpection and repair :Superphénix SGU Ultrasonic probe for Superphénix steam generator tubes

22. Nettoyage sans asservissement 1 passage 2 passages 3 passages R&D for Repair : welding after sodium trace removal • Laser sodiumsweeping • . maxi. 40 W • . 12 ns pulses • . 120 Hz • . 3,5x3,5 mm2 • . 45 to 1100 mm/mn • TIG welding after sodium removal

23. Pool / loop comparison • » potential damage » approach has to be undertaken in every case • The comparison depends on general review of ISI approach : 8 above mentionned criteria have to be taken into account • As a general matter : • Pool concept : favouring design simplicity, but more difficult access (larger size and integrated components) • Loop concept : favouring access facility, but more components to be inspected (3 vessels instead of 1, primary pipes, valves…)