makomon monitoring of the structural integrity of...
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VTT TECHNICAL RESEARCH CENTRE OF FINLAND LTD
MAKOMONMonitoring of the structuralintegrity of materials andcomponents in reactor circuitSAFIR2014 Final Seminar 20.3.2015Tarja Jppinen, Jonne Haapalainen,Esa Leskel, Ari Koskinen, Kari Lahdenper,Antti Tuhti
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220.3.2015 2
MAKOMON 2011-2014Nondestructive testing/evaluation NDT/NDEof NPP primary circuit
NDE applications for detecting cracks in primary circuit componentsUltrasonic applicationsRadiographyEddy Current
New ultrasonic methods,Laser ultrasoundNonlinear ultrasonics
Ultrasonic simulation and PODEddy current inspection techniques for primary circuits
Magnetite in Steam GeneratorsEddy current simulation
Digital Radiography
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320.3.2015 3
MAKOMON 2011-2014Nondestructive testing/evaluation NDT/NDEof NPP primary circuit
NDE applications for detecting cracks in primary circuit componentsComparison of artificial flaws in austenitic steel welds withNDE results compared to real measurements / DE
Simulation and PODUltrasonic simulation of the defects in primary circuit components and PODModel assisted POD calculations for fatigue flaws
Eddy current inspection techniques for primary circuitsMagnetite in Steam GeneratorsMeasurements of Magnetite Piles on Steam Generator Tubing with Eddy CurrentTechniques
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Comparison of artificial flawsin austenitic steel welds withNDE methods
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520.3.2015 5
Background
Reliable evaluation of the performance of in-service inspectionprocedures, equipment and personnel requires representativeartificial defectsUltrasonic indications are dependent on defect characteristicslike roughness, crack opening, tilt, skew and branchingIt is crucial for the reliability to know how well artificial defectslike thermal fatigue or mechanical fatigue cracks correspond toservice-induced cracks
a) EDM-notchb) Welded crack simulationc) Grown crackd) Service-induced crack
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620.3.2015 6
Test blocks
Welded AISI 316L test plates:1. Thermal fatigue crack and EDM
notch2. Two mechanical fatigue cracks
MAKOMON
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720.3.2015 7
Methods
NDTPhased Array ultrasonicConventional ultrasonicComputed tomographyEddy Current
DTScanning Electron Microscope
Surface and fracture surfaceStereo microscope3D profilometryCross-section investigation
Optical Microscope
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MF crack
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Ultrasonic Inspections
Conventional ultrasoundPhased array ultrasonicmethods
influence of differentreflector properties onindications.
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9920.3.2015
Mechanical fatigue crack
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101020.3.2015
Thermal fatigue crack
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111120.3.2015
Tomographic x-rayimaging
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121220.3.2015
UT vs. DT measured height
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Conventional UT Phased Array UT Conventional UT Phased Array UT Conventional UT Phased Array UT
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1320.3.2015 13
UT vs. DT measured length
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Conventional UT Phased Array UT Conventional UT Phased Array UT Conventional UT Phased Array UT
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Notes from the results
Crack tips were observed in mechanical fatigue cracks but not inthermal fatigue crack
Higher frequency in ultrasonic testing can give more informationof crack morphology and can also enable accurate height sizingof shallow cracksPhased array UT seems to give more accurate results in heightsizing and conventional UT in length sizing
MAKOMON
MF MF TF
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Ultrasonic simulation andPOD
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1620.3.2015 16
POD -curve tells the probability for flawof certain size to be found.
What is the largest flaw that a NDT-method can miss?
At least 40 measurements is requiredto obtain POD-curve with reasonableconfidence
New measurement = moneyand time
Computer simulations tocreate new measurement points to POD-curve model assisted POD
Probability of detection (POD)
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1720.3.2015 17
Model assisted POD calculations for fatigue flaws
One popular way to measure the reliability of NDE areprobability of detection (POD) curves
Generating POD requires a large amount of measurements withartificial defects expensive
CIVA simulation program has been used to model fatigue cracksDevelopment of modelling tools allows fast and cheap way togenerate measurements
The model and measurements have been then combined tocreate data points for POD curve calculationsMeta-modelling has been implemented to accelerate themodelling efforts
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181820.3.2015
POD for MF flaw
Skew = (05), tilt = (905)Three different focal lawsThe a90 defect height is2.74 - 9.40 mm
The wide range is due todifference in measuredSNR valuesIf constant 17.3 dB SNRvalue (SW45) is used,the a90 values are2.74 mm (SW 45)2.90 mm (SW 55)3.04 mm (SW 70)
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Eddy CurrentMeasurements
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202020.3.2015
Measurements of Magnetite Piles on SG Tubingwith Eddy Current Techniques
MAKOMON
The goal was to furtherdevelop and test a techniquecapable to size the magnetitepiles within the SG tubing.Absolute techniqueFrequencies, between 10 and200 kHz
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212120.3.2015
Eddy Current Measurements with Single Probe
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Ampl
itude
[Vpp
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The distance between the top of the magnetite pile and the lower surface of the tubes [mm]
12,5 kHz
25 kHz
50 kHz
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Orientation of the magnetite pile indication
The best sensitivity wasachieved, when the eddycurrent frequency was low12.5kHz, 25kHz or 50 kHzExtension of the magnetitepile can be mappedSingle probe technique isfound more reliable
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Ampl
itude
(Y)
Amplitude (X)
50 kHz
12,5 kHz
25 kHz
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MAKOMONConclusion
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2420.3.2015 24
Conclusion
Artificial cracks from different manufactures in austenitic stainless steeltest blocks were sized with different ultrasonic techniques, x-raytomography and digital radiography
Results were compared to the true state defect dimensions as determinedby destructive analysis
The modelling and measurements was combined to create PODcurves for fatigue cracks
Many different POD curves were calculated using CIVA simulations andmeta-modelling. The results show the advantage of using meta-modellingto decrease the calculation times
Tests to map the magnetite existence in the steam generator tubingmock-up with eddy current technique have shown a single probetechnique more reliable
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TECHNOLOGY FOR BUSINESS
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