Advanced Visual Testing TechnologiesAdvanced Visual Testing Technologies for In-Vessel Inspection

Y hi i S t h1) J S ki2) T O t b 2)Yoshinori Satoh1), Jun Suzuki2), Toru Ootsubo2)

1) Power and Industrial systems R&D Center,2) Isogo Nuclear Engineering Center,g g g ,

Power Systems Company, Toshiba Corporation

July 26, 2009

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BackgroundBackground

In-Vessel Visual Inspection (IVVI) as ISI based on the JSME S NA1–2004 :The following reactor internals is inspected b VT 3 for the standard inspectioninspected by VT-3 for the standard inspection;

Core Shroud;Jet pump;Shroud support;Top guide, Core plate and so on.

Individual Inspection for reactor internal is also needed;Individual Inspection for reactor internal is also needed;Inspection for stress corrosion cracking;Long interval compared to standard inspection (ex: 10years, 25years)EVT 1 should be used for the individual inspection;EVT-1 should be used for the individual inspection;

Enhancement of NDE technique is required;Advanced VT technique to achieve high accuracy; ECT or Laser-UT as alternative inspection for visual;High accuracy Ultrasonic testing (PA UT technique); and,Delivery and positioning technique.

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H4 Inside X-ShapeH7b Y-Shape

y p g q

Overview of TOSHIBA IVI TechnologiesOverview of TOSHIBA IVI TechnologiesIVI: In Vessel Inspection

Scan Device Inspection Technique

Phased Array UTISI Devices Equipment & Probe Family

B-Scan Image by 2D PAUT

3D Image by 3D PAUT

IVI: In-Vessel Inspection

In-vessel tools

High accuracy flaw depth sizing on weld surface by immersion

Probe Family

SCC

by 2D PAUT

SDH’s

by 3D PAUT

SCC

immersion technique.

Laser UT & ECT PT PT

Laser UT ECT

High resolved flaw detection and length & depth i i i th

ROV

SCC Specimen(1) SCC Specimen(2)

Advanced VTCrack

sizing in the reactor water.

Shroud

Super Resolution VT system3D VT system

SCC Specimen(3)

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Super Resolution Processing

Original

Phased Array UT

Ultrasonic beam is steered and f d b h t ll d

Beam Focusing Beam steering

ExcitingPulses

Elements

Beam Focusing Beam steering

ExcitingPulses

Elements

Beam Focusing Beam steering

ExcitingPulses

Elements

Principle

focused by phase controlled excitation of multiple array elements

FocalPoint

BeamDirection

WaveFront

FocalPoint

BeamDirection

WaveFront

FocalPoint

BeamDirection

WaveFront

Feature● Real time B-scan image carried out

FrontFrontFront

+ 45° 0°- 45°Water gap

Normal beam Angle beamExample of

array probes

gfor objective region

● Inspection condition can be changed according to defects and

+ 45 045

SC

C depth

(10mm

) + 4

5

Tip echo

changed according to defects and objective components

● Focused longitudinal wave is

-4

5°

0°

5°

SCCeffective for inspection of welds

● Immersion technique is notaffected to the surface condition

256chArray probe

Specimen(t=40mm)

SurfaceBackSurface

SCC

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affected to the surface condition p o eExample of B-scan image

Laser UT – PWR BMI

Work platforms

Optical fiber

Laser

Interferometer

Pulse

Laser

Principle

Cable tray

Insert tube(scanning

Transmission(Sizing)

SAW

CrackReflection(Detection)

Detection Laserm

(scanning mechanisms)

Optical fiber

R H E

18

Generation Laserand Laser Peening

R. H. E

Optical head

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and Laser Peening

Remotely Operated Vehicle (ROV) - Lineup

Shroud

Jet Pump

Shroud ROV

Shroud SupportShroud Support

ROV

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Shroud Support Small VehicleROV

ROV - FeaturesA li bl t i l i ti d l i ll- Applicable to in-vessel inspection and pool inner wall

inspection with highly accurate positioning capability.

Shroud ROV・ Accessible to 55 mm and more;

Small Vehicle・Approximately Dia. 140mm(Main body);

Shroud Support ROV・Drive below baffle plate・Demonstrated to EPRI;

・Demonstrated to EPRI;・Multi purpose use attaching various head (e g UT and B shing)

・Accessible to entire surface to be inspected;・Demonstrated to EPRI;

・Multi purpose use attaching various head (e.g. UT and Brushing).

(e.g. UT and Brushing). ・Manual operation; ・Stable by touching wheels on target.

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Operating Experience

Shroud VT 3 EVT 1 & UT Core Spray Piping / Sparger

・ VT-3, EVT-1 & UT(Phased array)

Core Spray Piping / Sparger・ EVT-1・ VT-3

J tJet pump･ VT-3, EVT-1Beam inspection: EVT-1, UTSet screw tack welds: EVT-1・ Set screw gap: VT-3・ Wedge & Rod wear: VT-3

Shroud support・VT-3

H7 H10: EVT 1 & UT

CRD housing & Stub tube・ VT 3 ・EVT 1

g・ H7, H10: EVT-1 & UT(Phased array)

・ H8, H9: EVT-1・ VT-3 ・EVT-1・ UT (Phased array)

BMI Nozzle （PWR)

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BWR Internals ・ UT (Laser UT)

Ad d VT T h l iAd d VT T h l iAdvanced VT TechnologiesAdvanced VT Technologies

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Requirement for VT technologies◆ Visual Testing (VT) for IVI

Detecting

In Vessel

gCracks

Inspector

Indirect visual Inspection

Adjusting camera manually while monitoring

・ VT is usually performed as “indirect” visual inspection using remote

cameras because target objects are under water and in high radiation area.

I t d t t k f f i t l t t th it

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・ Inspectors detect cracks on surface of internal structures on the monitor.

Requirement for VT technologies◆ Visual Testing (VT) for IVI

Detecting

In Vessel

gCracks

Inspector

Indirect visual Inspection

◆ Motivations

・Simplifying adjustment worksImageImage

Software

・Simplifying adjustment works

・Enhancing visibility on the monitor

・Providing intuitive visual interfaceOpticalOpticalDesignDesign

processingprocessing ・・SR VTSR VT・・3D VT3D VT

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Providing intuitive visual interface DesignDesignHardware

Super Resolution Technique

Raw data SR Image

◆ Example result of Super Resolution processing

SR processing

Spatial ResolutionSpatial Resolution

Super Resolution(SR)

Low Resolution (LR)

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(SR)(LR)

Overview of Super Resolution Technique◆ Principle of SR◆ Principle of SR

frame 1

Measuring relative position between frames in sub-pixel frame 2 paccuracy.

By superimposing the frames in sub pixel accuracy finer

Sub-pixel shift

in sub-pixel accuracy, finer grid (pixel) is composed.

Multiple frames(Temporal information)

Higher spatial resolution(Spatial information)

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(Temporal information) (Spatial information)

Overview of Super Resolution Technique

◆ Effects by applying Super Resolution (SR)

SR k hi h l ti i f l l ti id Thi• SR can make higher resolution images from a low resolution video. This behavior is equal to making camera close to objects.

→ SR can reduce difficult camera adjustment works jsuch as making cameras close to objects in narrow space. In other words, SR can reduce VT time.

• SR can be performed without expensive hardware but with software.

→ It can prevent from increasing in cost. It can prevent from increasing in cost.

• SR can enhance the resolution of VT video ONLY from frames in the id ith t dditi l i f tivideo without additional information.

→ SR has applicability to visual inspection activities.

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Overview of Super Resolution Technique◆ Algorithm construction for Super Resolution Imaging System◆ Algorithm construction for Super Resolution Imaging System

Raw video

①Measurement of relativeInterest FrameFrame 0

①Measurement of relative location in sub-pixel accuracy and evaluating i il it t i t t f

Frame 1similarity to interest frame.

②The intensity of HR image i ti t d f ti lA few

・

Frame 2is estimated from optimal frames statistically.

A few seconds

・・

Higher resolutionstill image

Frame Nstill image

N optimal frames One still image

①’ Optimal frames are

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frames One still imageregistered automatically.

Experimental Results◆ Experimental Configuration◆ Experimental Configuration

①Raw videoNTSC

Indirect

・CCD: 38Mpixel・Focus: f=25mm

Camerad ect

monitoring

Test PieceSR processingWD

Scan

X-Y stage②SR Image

SR: Super Resolution

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SR: Super ResolutionWD: Working Distance

Experimental Results◆ Case 1

SCC Test Piece Condition

◆ Case 1

Working Distance: 195mmField of View: 50mm×38mm

Condition

Field of View: 50mm×38mm

Resolution： 70μm/pixel

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SCC: Stress Corrosion Cracking

Experimental ResultsSR image

(Part of Test Piece)Raw Video

(Part of Test Piece)

Crack

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SR processing can enhance the crack in higher resolution

Experimental Results◆ Case 2

Cylindrical Test Piece Condition

◆ Case 2

Working Distance: 293mmField of View: 100mm×75mm

Resolution： 156μm/pixel

14mm

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Experimental ResultsRaw Video

(Part of Test Piece)SR image

(Part of Test Piece)

1 mil wire(0 0254mm）(0.0254mm）

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SR processing can enhance thin wire in higher resolution.

Experimental Results◆ Case 3

Cylindrical Test Piece Condition

◆ Case 3

Working Distance: 586 mmField of View: 150mm×113mm

Resolution： 234μm/pixel

14mm

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Experimental ResultsRaw Video

(Part of test piece)SR image

(Part of test piece)

1 mil wire(0.0254mm)( )

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SR processing can enhance thin wire in higher resolution.

Applicability Evaluation◆ Q antitati e E al ation of S per Resol tion (SR)◆ Quantitative Evaluation of Super Resolution (SR)

In order to evaluate applicability of SR “quantitatively”, we conducted visibility evaluation based on VT 1 grade of ASMEconducted visibility evaluation based on VT-1 grade of ASME.※ VT-1 must be demonstrated capable of resolving characters whose height is 1.1mm.

Raw frame SR image

Characters are unreadable because of low resolution

Characters become readable by use of SR

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Applicability Evaluation◆ Definition of Q antitati e Visibilit

For the evaluation, we compare the visibility of the characters S R l ti (SR) i t th t id

◆ Definition of Quantitative Visibility

on Super Resolution (SR) images to that on raw videos.

VisibilityVisibility

Readability: Ratio of the number of VT-1 characters which 3 yexaminers could read to the number of all test characters.

Readability (%) = (Number of characters which examiners could read)

/(N b f ll t t h t )×100(%)/(Number of all test characters)×100(%)

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Applicability Evaluation◆ Experimental Configuration◆ Experimental Configuration

①Raw video・CCD: 38Mpixel

NTSC

CameraIndirect

monitoring

p・Focus: f=8mm

SR processing(a) WD

(b) Scan

VT-1 charactersp g(a) WD

X-Y stage ②SR ImageSR: Super ResolutionWD: Working Distance X Y stage ②SR Image

(a) Comparing readabilities while changing working distance(b) Comparing readabilities while changing scanning speed

WD: Working Distance

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(b) Comparing readabilities while changing scanning speed

Applicability Evaluation◆ Comparison result while changing WD when scanning speed is 10mm/sec

100

◆ Comparison result while changing WD when scanning speed is 10mm/sec

75

%)

Visibility is enhanced

50

abili

ty (

%

2 R Vid (X1)

Rea

da

25 Raw Video (X1)One Frame (X1)SR Image (X3)

0

50 100 150 200SR S R l ti

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Working Distance (mm)SR: Super ResolutionWD: Working Distance

Applicability Evaluation◆ Comparison result while changing scanning speed when WD=200mm

100

Raw Video (X1)( )

◆ Comparison result while changing scanning speed when WD=200mm

75

One Frame (X1)SR Image (X3)

50bilit

y (%

)

25

Rea

dab

Vi ibilit i25 Visibility is enhanced

0

0 5 10 15 20 25S i S d ( / )SR S R l ti

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Scanning Speed (mm/sec)SR: Super ResolutionWD: Working Distance

Applicability Evaluation◆ Summary of evaluations

We can confirm that the use of the Super Resolution

It will be able to become easier and more flexibly to set

We can confirm that the use of the Super Resolution (SR) brings the following effects.

• It will be able to become easier and more flexibly to set the working distance of cameras in VT because SR can give nearer images with software.give nearer images with software.

• SR will be able to prevent camera motions from reducing visibility on monitor.g y

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3DVT Technique• 3-dimensional VT (3DVT) technique is based on Stereo

vision.

◆ Some information can be provided …(1) C k l th d t 3D th(1) Crack length and etc. on 3D path(2) 3D shapes (wire-frame, surface and texture model)(3) Cross-section view on reconstructed object surface(3) Cross-section view on reconstructed object surface

◆ Main Processes are◆ Main Processes are …(1) camera calibration (relative camera position and angle)angle)(2) image matching of 2 images from each camera(3) 3D-coordinates calculation using image pixel and

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camera parameters

Overview of 3DVT Technique• Configuration of this system with 3D camera head,

control device and processing device:

Power

Control Device

Power supply

Processing Device（PC)

3D Camera • 3D Camera head is consist of 2 camera and rotating table.

• Control Device is for signal communication and operation.

• Processing Device perform image processing calibration and

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Processing Device perform image processing, calibration and 3D-measurement process.

3D Camera for Flat Target3D Camera

Head3D Monitor Liq. Crystal

Glasses

EyesRight Side Image

Left Side Image

Eyes

Synchronous Signal Stereoscopic Effect

Left Side Image

Right Side Image

Effect

CCD

Prism

Liq. Crystal Shutter

Liq. Crystal Glasses

Mirror

Target

3D Camera Head

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3D Camera for Flat Target

◆ Configuration of 3D Camera Head

◆ Surface Shape Measurement Result

T t M i

■Field of View18mm x 14mm

Texture Mapping (Part of test piece)

■Depth-Resolution100μm

Right Side View Left Side View

Left Side Image(Part of test piece)

Right Side Image(Part of test piece) Wire Frame

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( p ) ( p ) Wire Frame(Part of test piece)

3D Camera for Pipe Target◆ M t t t◆ Measurement target(1) Welding part of CRD Housing and CRD stub tube (J-weld)(2) Welding part of CRD stub tube and RPV (3D-weld)( ) g p ( )

• In order to measure welding part of CRD stub tube …

◆ Restricted conditions

Vertical Scanning Part

(1) To mount on access device for being possible to scan and measure(2) To able to access and measure in a narrow space(3) To fix working distance (250mm in air)

CRD Housing

J elding part

Turn Scanning Part(Access Device)

Vertical Scanning Part(Access Device)

Turning and Scanning

(3) To fix working distance (250mm in air)

J welding part

CRD stub tube

3D welding part

Cramp Part for fixing device(Access Device)

M t H dJ welding part

Nuclear Reactor Pressure Vessel (RPV)

Measurement Headg

3D welding part

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(RPV)

3D Camera for Pipe Target◆ C fi ti f t t t h d

Camera: 640x480pixels, 1/4 inch (6.4mm) CCDHead Si e 50mm(L) 70mm(W) 30mm(D)

◆ Configuration of prototype measurement head

Head Size: 50mm(L)x70mm(W)x30mm(D)Measurement accuracy (depth): 0.5mm

Camera 1 Camera 2

Access Device

Light

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g

3D Camera for Pipe Target◆ Results of Mockup Experiment

Both welding parts (J-weld and 3D-weld) of the Mock-up were able to be measured surface shape of welding part.p g pWe can confirmed that our 3DVT technique and prototype measurement head were effective.

R d 3D h f R d 3D h f

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Reconstructed 3D shape of Mock-up J-weld

Reconstructed 3D shape of Mockup 3D-weld

Flexible 3D Camera System◆ Main functions◆ Main functions

Covering from micro measurement (crack length) to macro measurement (position, distance, level of internal structure) for Jet-p mppump

◆ Specifications(1) Measurement accuracy (depth): ( ) y ( p )

0.5mm (WD= 100mm), 5.0mm (WD = 600mm); (2) Field of view: 100x75mm or more

WD: Working Distance

Work positionFOV

Working distance

Cross point

θ

Work position

Camera 1

θ’

Stereo di it Camera 2

Optical axis

Rotating

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disparity Camera 2axisg

table

Prototype Head

Flexible 3D Camera System◆ R k bl i t◆ Remarkable points

(1) Working distance is variable change as rotating camera(2) Cross point of optical axis is adjusted most suitable angle automatically(3) Size measurement covering from tiny crack to large structure(4) Measuring distance on 3D path and direct distance between 2 ( ) g ppoints

Camera 1Camera 2

Rotate direction

Optical axisθ

Work position (short)

Working distance

θ

Work position (long)

Stereo disparity

Work position (short)

Field of view

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Cross point of optical axisWork position (long)

Flexible 3D Camera System◆ Example of 3D measurement (Main GUI)

Raw Image (Part of test piece)Raw Image (Part of test piece)

Setting 2 points (user action)

Reconstructed 3D shape(Part of test piece)

Path along surfaceCross-section

Linear path between 2 pointsDistance (linear)

( f )Distance (along surface)

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Flexible 3D Camera System◆ E l f 3D t i

A measurement result of a test piece which has welding part

(Working Distance: 350mm)

◆ Example of 3D measurement using zoom

(Working Distance: 350mm) Raw Image (Part of test piece)

Reconstructed 3D shape(Part of test piece)

Distance (linear)Distance (linear)

Distance (along surface)

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Flexible 3D Camera System◆ E l f 3D t i

A measurement result of a test piece which has welding part

(Working Distance: 350mm)

◆ Example of 3D measurement using zoom

(Working Distance: 350mm)

Raw Image (Part of test piece)

Reconstructed 3D shape(Part of test piece)

Distance (linear)Distance (linear)

Distance (along surface)

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Flexible 3D Camera System◆ A li bilit E l ti f Fl ibl 3D C

In order to verify applicability of this 3D VT system, we performed 3D measurement for the surface of Jet pump mock-up in full scale tank.

◆ Applicability Evaluation of Flexible 3D Camera

p p p

20m (Underwater)20m (Underwater)

Head Example image of the surface f J t k

Camera 1

Camera 2 J t P M k

25m (Underwater)

of Jet pump mock-up

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Camera 2 Jet Pump Mock-up

Flexible 3D Camera System◆ M t R lt f J t P M k

We can confirm that the profile (cross-section) data on the Jet Pump surface was obtained along cylindrical surface

◆ Measurement Result of Jet Pump Mock-up

surface was obtained along cylindrical surface. Camera 1

(Part of JP Mock-up)Camera 2

(Part of JP Mock-up) Profile on 3D surface(Part of JP Mock-up)

Distance (along surface)

Reconstructed 3D shape(Part of JP Mock-up)

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( )

Flexible 3D Camera System

Downsizing of proto-type 3D Camera head for narrow space

Camera 2 Rotating Table

Camera 1

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Flexible 3D Camera System• Developed the prototype measurement system by the

3DVT technique for shape reconstruction and crack length measurementlength measurement.

• Result of std. is less than 0.5mm (measurement resolution in design)resolution in design).Confirm to able to measure difference in level of 0.5mm.

• Conducted mock-up experiment for demonstrating the• Conducted mock-up experiment for demonstrating the effectiveness of 3DVT technique and the applicability of prototype measurement head of this system using p yp y gsimulated test piece of actual equipment shape.

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ConclusionConclusion

• Toshiba has various advanced NDE technologies, such as phased array UT and Laser-UT, and widely y yapplies these technologies to actual in-vessel inspections for nuclear power plants.

• In particular, distinctive VT technologies have been developed;

- Super resolution (SR) VT enables to produce a still i h i 3 ti b tt l ti f i i limage having 3 times better resolution from original low-resolution video data.

3 di i l (3D) VT bl t tit ti l- 3-dimensional (3D) VT enables to quantitatively reconstruct object shapes with an accuracy of 0.5mm.

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