In-Service Inspection &Repair of Sodium Cooled Reactors General strategy and feedback experience
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Transcript of In-Service Inspection &Repair of Sodium Cooled Reactors General strategy and feedback experience
October 2005 1DTN/STPA/LTTSISI&R_Rosatom_FB2005
•In-Service Inspection &Repair
of Sodium Cooled Reactors
General strategy and feedback experience
F. Baqué
DEN Cadarache
October 2005 2DTN/STPA/LTTSISI&R_Rosatom_FB2005
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
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Main and guard vessels
Core supporting structures (diagrid…)
Component skirts
Above core structure
Pump to diagrid pipe
Control rods / assemblies alignment
Secondary circuits & components
BackgroundFrench and international feedback experience
of existing sodium cooled Fast Reactors
(mainly Phénix and Superphénix Plants, but also Monju)
October 2005 4DTN/STPA/LTTSISI&R_Rosatom_FB2005
Background
Studies for innovative projects
(mainly EFR, but also ALMR, DFBR, BREST-300)
USA
Russia
October 2005 5DTN/STPA/LTTSISI&R_Rosatom_FB2005
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
October 2005 6DTN/STPA/LTTSISI&R_Rosatom_FB2005
ISI&R parameters (continued)
- Reactor conditions : Temperature, aerosols, radiation, air ingress risk…
- 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
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ISI parameters : application to EFR project
October 2005 8DTN/STPA/LTTSISI&R_Rosatom_FB2005
Large inspectionMedium inspection
Low inspection
Seriousnessof
damage for safety
No inspection
Cumulated potential damages
hight
medium
low
low medium hight
ISI codes and standards
•The « potential damage method » : for each structure
•Limited to ASME section XI division 3
October 2005 9DTN/STPA/LTTSISI&R_Rosatom_FB2005
ISI codes and standards
•« potential damage method » :Large
inspection
Medium
inspection
Low inspecti
on
No inspecti
on
Initial damage Time
Cumulated damage
Real damage
Estimated damage
Revised along plant life (all situation counting)
Initiated at the design phase calculation of damages evaluation of failure effects
October 2005 10DTN/STPA/LTTSISI&R_Rosatom_FB2005
Potential damage method : application to Superphénix
safety vesselslab connectionheterogeneous
welding
premary vesselslab connection
platelagesupporting shell
diagrid supportlateral supporting
zone
core support plateboxessupport weldingtables
connecting pipebetween pumpand diagriddiagrid inletpump outletpump support
control rodalignment
roof slab androtating plugrotating plug
supportcomponent
support
boxes
above corestructureheadsodium free levelexternal shirtwelding
High surveillanceIntermediate surveillanceLow surveillance
October 2005 11DTN/STPA/LTTSISI&R_Rosatom_FB2005
ISI at the Design phase
An iterative process :
Preliminary ISI evaluation of SFR concept
More detailed ISI&R requirements
Identification of priorities and recommendations
SFR consistent design
1
2
3
4
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ISI&R criteria at Design stage :
Proposal for ISI&R criteria utilization at Design stage
8 ISI&R criteria
(1)
ISI&R operation
quality
(2)
ISI&R operation duration
(3)
ISI&R operation
means
(1)+(2)+(3)
ISI&R operation
risks
Notation along
feedback experience
+ o -
ISI results = defect detection
and sizing, image
recording, télémtry
measures…
ISI operations sometimes longer than expected
(technical or human
problems)
ISI operations with staffs and tools (robots,
sensors…) to be
available
Risks :
of poor result quality
of over-duration
of technical or human
difficulties…
October 2005 13DTN/STPA/LTTSISI&R_Rosatom_FB2005
ISI&R criteria at Design stage :
quality
duratio
n
means
Less important : Reactor size o + o Structure characteristics + - -
Very important : Tools & techniques + + + Design simplicity o + + Access facility o + +
Not so important : Modularity o - - Easily removable parts o o o Reactor conditions o - -
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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
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R&D for the Inspection of immersed structures :in sodium ultrasonic telemetry
in water qualification
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Inspection of core supporting structures :Phénix experience
Ultrasonic inspection of 4.5 m long shell (immersed in sodium)
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Repair of removable componants :handling out of primary vessel
Handling of the drilling machine for Superphénix core catcher piercing : mechanical process 20 m long machineThrough roof penetration Under sodium operation 3 year developt & qualification
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In-Service Inspection of Superphénix PlantPrimary Vessel Welds : the Rapid Inspection
Machine (MIR)
Primary vessel
Guard vessel
2 cameras
US sensors
700 mm
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Repair of immersed structures :Superphénix experience
Repair of IHX argon feeding tube (1995)
Leak zone
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Core outlet sodium behaviour :Superphénix acoustic monitoring
6 metallic bars within above core structure
Control rod impact
Argon in primary sodium
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Tube bundle inpection and repair :Superphénix SGU
Ultrasonic probe for Superphénix steam generator tubes
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R&D for Repair : welding after sodium trace removal
Nettoyage sans asservissement
1 passage
2 passages
3 passages
• Laser sodium
sweeping. maxi. 40 W
. 12 ns pulses
. 120 Hz
. 3,5x3,5 mm2
. 45 to 1100 mm/mn
• TIG welding after sodium
removal
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Pool / loop comparison
The comparison depends on general review of ISI approach : 8 above mentionned criteria have to be taken into account
» potential damage » approach has to be undertaken in every case
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…)