Application of a FMC/TFM Ultrasonic System to the BEHAVIOURS … · 2016-11-15 · Say It, Do It Simplify It Think Top and Bottom Line Integrate and Collaborate Tell It As It Is BEHAVIOURS

Say It, Do It Simplify It Think Top and Bottom Line Integrate and Collaborate Tell It As It Is

BEHAVIOURS

V A L U E S S A F E T Y I N T E G R I T Y E X C E L L E N C E P E O P L E & C I T I Z E N S H I P

Application of a FMC/TFM Ultrasonic System to the Inspection of Austenitic Welds R.L. ten Grotenhuis1, A. Chen2, A. Hong1, Y. Verma1 1Ontario Power Generation Inc. Toronto Ontario 2 Kinectrics Inc. Toronto Ontario November 2016

OPG INTERNAL USE ONLY VALUES S A F E T Y I N T E G R I T Y E X C E L L E N C E P E O P L E & C I T I Z E N S H I P

Agenda

CANDU Primary Heat Transport – Flow Accelerated Corrosion Full Matrix Capture & Total Focussing Method Extension to other applications A general approach to Austenitic welds Weld model and material property considerations Experimental Equipment Results and conclusions


FAC in CANDU Primary Heat Transport

Oblique view of reactor face upper quadrant showing feeder pipes

Feeder pipe attachment to Fuel channel end fitting Locations subject to

localised FAC attack

Examples of localised FAC attack


Background – FMC/TFM Solution

FMC necessary for acquisition on small diameter fitting to fitting joints with weld cap 2-stage TFM solution applied to solve for:

Interface surface Interior volume beyond interface

Individual profiles created every 0.5 mm about the circumference

Stacked to yield 3D representation of inspected fitting


MIT Inspection Results

Examples of typical coverage obtained during field inspections, colour coded for thickness.

Mono tone grey rendering of 3D image depicting photorealistic response left, with a photo of a lab sample right


Inspection Opportunity

Seek further applications for MIT CANDU system pressure

boundary: Zirconium fuel channels, Inconel steam generator tubing, Carbon steel in balance of Primary

Heat Transport

Dissimilar metal welds: C/S to Inconel 600 nozzle and venturi flow measurement elements 3½” & 4” NPS, sch 80, Qty - 52 welds/unit Austenitic welds in Moderator

system, 8” NPS, 304 SS with 308L fill, Qty – 10 weld/unit


Approach to Austenitic welds

Required adaptations TFM beamformer code as follows: • Retain the TFM/edge detection solution to the exterior surface • Inhomogeneous material: Divide the inspection region into series of

homogenous regions • Anisotropic characteristic: directionally dependant velocity per

material properties (slowness surface) • Manually locate model of the weld in the interior search region

applying dilations as needed to match weld width/thickness • Solve all points in parent material that do not transit weld material • Apply Fermat principle for weld material beginning with points

closest to transducer element

Imaging to be performed in L-wave mode All points evaluated, however only displays points meeting

intensity threshold Processing times significantly greater than for isotropic case


Austenitic Weld Sample

EPRI: 6 Inch nps Sch 80 304SS with ‘J’ groove weld prep, 308L fill material

5 implanted defects: 2 thermal fatigue cracks, 2 side wall LOF, Slag line

One of each type selected

Significant deformation occurred during weld process


Model Development

Analytical solutions exist for Vee and double Vee welds however have not been developed for U groove configurations

Alternative – model based on weld macrograph found to closely match material & geometry of sample

Divided into 27 regions – angles varying from 0 to +/- 63 degrees wrt vertical axis

Weld symmetry was used as a simplifying assumption to ease coding

From Wirdelius et al, Swedish Nuclear Power Inspectorate


Slowness Surface for 308L

The wave equation for a general elastic anisotropic medium may be written as For a plane wave, its characteristic can be determined by the

Christoffel equation

where is the Green-Christoffel tensor.

li

kijkl

i

xxuC

tu

∂∂∂

=∂∂ 2

2

2

ρ

[ ][ ] 02 =−Γ jij uijc δρijΓ


Slowness Surface for 308L

The phase velocity c can be obtained by solving the characteristic equation In general, there are three solutions for a give wave propagation

direction, pseudo L wave, pseudo S-horizontal, pseudo S-vertical The group velocity is defined as

It can be shown that

02 =−Γ ijcij δρ

ii K

V∂∂

=ω

cuunC

V kjlijkli ρ=


Slowness surface

Graphic (3) of slowness surface with group vector and phase vector at varying orientations

0.0001

0.0002

0.0003

0.0004

0.0005

30

210

60

240

90

270

120

300

150

330

180 0

Slowness surface

y

qS1qS2qL

0.0001

0.0002

0.0003

0.0004

0.0005

30

210

60

240

90

270

120

300

150

330

180 0

Slowness surface

y

qS1qS2qL

Phase Vector (a) 20 degree (b) 45 degree (c) 70 degree

0.0001

0.0002

0.0003

0.0004

0.0005

30

210

60

240

90

270

120

300

150

330

180 0

Slowness surface

y

qS1qS2qL


Phase Coherence

Underlying assumption when applying TFM – phase remains coherent with group Use of analytic signal representation significantly more sensitive

to phase error than other beamformers e.g. phased array Anisotropic materials – group, phase velocity differential results in

loss of coherence which varies depending upon path in material Necessary to compensate for the loss of phase coherence


Experimental Apparatus

5 Axis immersion tank Peak NDT – 128 ch Micropulse 5 FMC OPG proprietary Neovision data

acquisition package


Transducer Characteristics

fnom 2.9 MHz

Pitch 0.47 mm

BW (%) 42

Pulse Dur’n 1245 ns

fnom 5.6 MHz

Pitch 0.30 mm

BW (%) 75


fnom 7.7 MHz

Pitch 0.27 mm

BW (%) 71



Results – 2.9 MHz scans

Without weld model

With weld model

Root crack Side Wall LOF Slag line




Without weld model

With weld model




Without weld model

With weld model


Discussion

Improvements to imaging largely confined to the 3 MHz transducer Marginal improvement in performance for the 5.6 MHz transducer Ineffective for 7.7 MHz, likely due to the influence of grain size Issues to be investigated:

• Accuracy of the weld model • Shrinkage and twist of weld axis evident in weld sample • Fabrication process of the sample vis a vis processes applied to implant

defects, • Phase error introduced when applying a phase shift of a single frequency, • Model adaptation based on perturbation of pitch-catch focal law

Current efforts are directed to re-assessment of code modification for potential improvements and providing a better means to fit the model to the search volume


Conclusions

Initial efforts have yielded limited but encouraging results The model developed may not necessarily correspond to the grain

structure of the sample Further work in the following areas:

Model: Verify the weld process of the model matches that of the sample Sample: Additional tests on samples with known metallurgy and known defect

locations Algorithm: Assess the error introduced when performing phase shift Automate the placement of the model in the search region

The authors wish to thank EPRI for providing samples for this project, in particular we wish to thank Dr. G. Connolly for his assistance and insights.


End

Thank - you

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Documents

Application of a FMC/TFM Ultrasonic System to the BEHAVIOURS … · 2016-11-15 · Say It, Do It Simplify It Think Top and Bottom Line Integrate and Collaborate Tell It As It Is BEHAVIOURS