for In-Vessel Inspection

Transcription

1 Advanced Visual Testing Technologies for In-Vessel Inspection Yoshinori i Satoh 1), Jun Suzuki 2), Toru Ootsubo 2) 1) Power and Industrial systems R&D Center, 2) Isogo Nuclear Engineering g Center, Power Systems Company, Toshiba Corporation July 26, /45 Background In-Vessel Visual Inspection (IVVI) as ISI based on the JSME S NA :The following reactor internals is inspected 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; Inspection for stress corrosion cracking; Long interval compared to standard inspection (ex: 10years, 25years) 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. H7b Y-Shape H4 Inside X-Shape 2/45

2 Overview of TOSHIBA IVI Technologies Scan Device ISI Devices In-vessel tools Phased Array UT High accuracy flaw depth sizing on weld surface by immersion technique. Inspection Technique Equipment & Probe Family IVI: In-Vessel Inspection B-Scan Image by 2D PAUT Laser UT & ECT PT PT SDH s SCC 3D Image by 3D PAUT SCC Shroud ROV High resolved flaw detection and length & depth sizing i in the reactor water. Advanced VT Laser UT SCC Specimen(1) Super Resolution VT system 3D VT system ECT SCC Specimen(2) Crack SCC Specimen(3) Original Super Resolution Processing 3/45 Principle Ultrasonic beam is steered and focused by phase controlled excitation of multiple array elements Feature Phased Array UT Beam Focusing Focal Point Real time B-scan image carried out for objective region Inspection condition can be changed according to defects and objective components Focused longitudinal wave is effective for inspection of welds Immersion technique is not affected to the surface condition Normal beam Exciting Pulses Elements Beam Direction Wave Front - 45 Beam steering Angle beam Tip echo SCC depth (10mm) Back Surface Surface Example of array probes Water gap SCC Specimen (t=40mm) Example of B-scan image 256ch Array probe po 4/45

3 Laser UT PWR BMI Work platforms Optical fiber Principle Pulse Laser Laser Interferometer Cable tray Insert tube (scanning mechanisms) SAW Reflection (Detection) Transmission (Sizing) Crack m 18 Optical fiber Detection Laser RHE R. H. Optical head Generation Laser and Laser Peening 5/45 Remotely Operated Vehicle (ROV) - Lineup Shroud Jet Pump Shroud ROV Shroud Support ROV Shroud Support Small Vehicle 6/45

4 ROV - Features - Applicable to in-vessel linspection and pool linner wall inspection with highly accurate positioning capability. Shroud ROV Accessible to 55 mm and more; Demonstrated to EPRI; Multi purpose use attaching various head (e.g. UT and Brushing). Shroud Support ROV Drive below baffle plate Demonstrated to EPRI; Multi purpose use attaching various head (e.g. UT and Brushing). Small Vehicle Approximately Dia. 140mm(Main body); Accessible to entire surface to be inspected; Demonstrated to EPRI; Manual operation; Stable by touching wheels on target. 7/45 Operating Experience Shroud VT-3, EVT-1 & UT (Phased array) Shroud support VT-3 H7, H10: EVT-1 1&UT (Phased array) H8, H9: EVT-1 BWR Internals Core Spray Piping / Sparger EVT-1 VT-3 Jet pump VT-3, EVT-1 Beam inspection: EVT-1, UT Set screw tack welds: EVT-1 Set screw gap: VT-3 Wedge & Rod wear: VT-3 CRD housing & Stub tube VT-3 EVT-1 UT (Phased array) BMI Nozzle (PWR) UT (Laser UT) 8/45

5 Advanced d VT Technologies 9/45 Requirement for VT technologies Visual Testing (VT) for IVI In Vessel Detecting Cracks 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. Inspectors detect t cracks on surface of internal structures t on the monitor. 10/45

6 Requirement for VT technologies Visual Testing (VT) for IVI In Vessel Detecting Cracks Inspector Indirect visual Inspection Motivations Simplifying adjustment works Enhancing visibility on the monitor Providing intuitive visual interface Software Image processing Optical Design Design Hardware SR VT 3D VT 11/45 Super Resolution Technique Example result of Super Resolution processing Raw data SR Image SR processing Low Resolution (LR) Spatial Resolution Super Resolution (SR) 12/45

7 Overview of Super Resolution Technique Principle of SR frame 1 frame 2 Measuring relative position between frames in sub-pixel accuracy. Sub-pixel shift By superimposing the frames in sub-pixel accuracy, finer grid (pixel) is composed. Multiple frames (Temporal information) Higher spatial resolution (Spatial information) 13/45 Overview of Super Resolution Technique Effects by applying Super Resolution (SR) SR can make higher h resolution images from a low resolution video. This behavior is equal to making camera close to objects. SR can reduce difficult camera adjustment works such 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. SR can enhance the resolution of VT video ONLY from frames in the video without t additional information. SR has applicability to visual inspection activities. 14/45

8 Overview of Super Resolution Technique Algorithm construction for Super Resolution Imaging System Raw video 1Measurement of relative Interest Frame 0 location in sub-pixel Frame accuracy and evaluating similarity il it to interest t frame. Frame 1 2The intensity of HR image A few Frame t 2 is estimated from optimal seconds frames statistically. Higher resolution Frame N 1 Optimal frames are registered automatically. N optimal frames still image One still image 15/45 Experimental Results Experimental Configuration CCD: 38Mpixel Focus: f=25mm Camera NTSC 1Raw video Indirect monitoring Test Piece WD Scan SR processing SR: Super Resolution WD: Working Distance X-Y stage 2SR Image 16/45

9 Case 1 SCC Test Piece Experimental Results Condition Working Distance: 195mm Field of View: 50mm 38mm Resolution: 70μm/pixel SCC: Stress Corrosion Cracking 17/45 Experimental Results Raw Video (Part of Test Piece) SR image (Part of Test Piece) Crack SR processing can enhance the crack in higher resolution 18/45

10 Case 2 Experimental Results Cylindrical Test Piece Condition Working Distance: 293mm Field of View: 100mm 75mm Resolution: 156μm/pixel 14mm 19/45 Experimental Results Raw Video (Part of Test Piece) SR image (Part of Test Piece) 1 mil wire (0.0254mm) 0254mm) SR processing can enhance thin wire in higher resolution. 20/45

11 Case 3 Experimental Results Cylindrical Test Piece Condition Working Distance: 586 mm Field of View: 150mm 113mm Resolution: 234μm/pixel 14mm 21/45 Experimental Results Raw Video (Part of test piece) SR image (Part of test piece) 1 mil wire (0.0254mm) SR processing can enhance thin wire in higher resolution. 22/45

12 Applicability Evaluation Quantitative Evaluation ation of Super Resolution (SR) In order to evaluate applicability of SR quantitatively, we conducted 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 23/45 Applicability Evaluation Definition of Quantitative Visibility For the evaluation, we compare the visibility of the characters on Super Resolution (SR) images to that t on raw videos. Visibility Readability: Ratio of the number of VT-1 characters which 3 examiners could read to the number of all test characters. Readability (%) = (Number of characters which examiners could read) /(Number of all test t characters) 100(%) 24/45

13 Applicability Evaluation Experimental Configuration CCD: 38Mpixel Focus: f=8mm Camera NTSC 1Raw video Indirect monitoring VT-1 characters (a) WD (b) Scan SR processing SR: Super Resolution WD: Working Distance X-Y stage 2SR Image (a) Comparing readabilities while changing working distance (b) Comparing readabilities while changing scanning speed 25/45 Applicability Evaluation Comparison result while changing WD when scanning speed is 10mm/sec 100 Reada ability (% %) Raw Video (X1) One Frame (X1) SR Image (X3) Visibility is enhanced Working Distance (mm) SR: Super Resolution WD: Working Distance 26/45

14 Applicability Evaluation Comparison result while changing scanning speed when WD=200mm Raw Video (X1) One Frame (X1) SR Image (X3) Readab bility (%) Visibility ibilit is enhanced 0 SR: Super Resolution WD: Working Distance Scanning Speed (mm/sec) 27/45 Applicability Evaluation Summary of evaluations 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. SR will be able to prevent camera motions from reducing visibility on monitor. 28/45

15 3DVT Technique 3-dimensional VT (3DVT) technique is based on Stereo vision. Some information can be provided (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 Main Processes are (1) camera calibration (relative camera position and angle) (2) image matching of 2 images from each camera (3) 3D-coordinates calculation using image pixel and camera parameters 29/45 Overview of 3DVT Technique Configuration of this system with 3D camera head, control device and processing device: Power supply Control Device 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 3D-measurement process. 30/45

16 3D Camera for Flat Target 3D Camera Head 3D Monitor Liq. Crystal Glasses Right Side Image Eyes Left Side Image Synchronous Signal Stereoscopic Effect CCD Left Side Image Right Side Image Prism Mirror Liq. Crystal Shutter Target 3D Camera Head Liq. Crystal Glasses 31/45 3D Camera for Flat Target Configuration of 3D Camera Head Field of View 18mm x 14mm Depth-Resolution 100μm Surface Shape Measurement Result Texture Mapping (Part of test piece) Right Side View Left Side View Left Side Image Right Side Image (Part of test piece) (Part of test piece) Wire Frame (Part of test piece) 32/45

17 3D Camera for Pipe Target Measurement target t (1) Welding part of CRD Housing and CRD stub tube (J-weld) (2) Welding part of CRD stub tube and RPV (3D-weld) In order to measure welding part of CRD stub tube Restricted conditions (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) Vertical Scanning Part CRD Housing Turn Scanning Part (Access Device) (Access Device) Turning and Scanning J welding part CRD stub tube 3D welding part Cramp Part for fixing device (Access Device) J welding part Measurement thead Nuclear Reactor Pressure Vessel (RPV) 3D welding part 33/45 3D Camera for Pipe Target Configuration of prototype t measurement head Camera: 640x480pixels, 1/4 inch (6.4mm) CCD Head Size: 50mm(L)x70mm(W)x30mm(D) Measurement accuracy (depth): 0.5mm Access Device Camera 1 Camera 2 Light 34/45

18 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. We can confirmed that our 3DVT technique and prototype measurement head were effective. Reconstructed 3D shape of Mock-up J-weld Reconstructed 3D shape of Mockup 3D-weld 35/45 Flexible 3D Camera System Main functions Covering from micro measurement (crack length) to macro measurement (position, distance, level of internal structure) for Jet- pump Specifications (1) Measurement accuracy (depth): 0.5mm (WD= 100mm), 5.0mm (WD = 600mm); (2) Field of view: 100x75mm or more WD: Working Distance Working distance Work position Cross point θ θ FOV Camera 1 Stereo Optical disparity it axis Camera 2 Rotating table Prototype Head 36/45

19 Flexible 3D Camera System 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 points Camera 1 Camera 2 Rotate direction Working distance Field of view θ θ Optical axis Work position (short) Stereo disparity Cross point of optical axis Work position (long) 37/45 Flexible 3D Camera System Example of 3D measurement (Main GUI) Raw Image (Part of test piece) Setting 2 points (user action) Reconstructed 3D shape (Part of test piece) Cross-section Path along surface Distance (linear) Linear path between 2 points Distance (along surface) 38/45

20 Flexible 3D Camera System Example of 3D measurement using zoom A measurement result of a test piece which has welding part (Working Distance: 350mm) Raw Image (Part of test piece) Reconstructed 3D shape (Part of test piece) Distance (linear) Distance (along surface) 39/45 Flexible 3D Camera System Example of 3D measurement using zoom A measurement result of a test piece which has welding part (Working Distance: 350mm) Raw Image (Part of test piece) Reconstructed 3D shape (Part of test piece) Distance (linear) Distance (along surface) 40/45

21 Flexible 3D Camera System Applicability Evaluation of Flexible 3D Camera In order to verify applicability of this 3D VT system, we performed 3D measurement for the surface of Jet pump p mock-up in full scale tank. 20m (Underwater) Camera 1 Camera 2 Head Jet Pump Mock-up Example image of the surface of fjet pump mock-up 25m (Underwater) 41/45 Flexible 3D Camera System Measurement Result of Jet Pump Mock-up We can confirm that the profile (cross-section) data on the Jet Pump 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) 42/45

22 Flexible 3D Camera System Downsizing of proto-type 3D Camera head for narrow space Camera 2 Rotating Table Camera 1 43/45 Flexible 3D Camera System Developed the prototype measurement system by the 3DVT technique for shape reconstruction and crack length measurement. Result of std. is less than 0.5mm (measurement resolution in design). Confirm to able to measure difference in level of 0.5mm. Conducted mock-up experiment for demonstrating the effectiveness of 3DVT technique and the applicability of prototype measurement head of this system using simulated test piece of actual equipment shape. 44/45

23 Conclusion Toshiba has various advanced NDE technologies, such as phased array UT and Laser-UT, and widely applies 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 image having 3ti times better resolution from original i low-resolution video data. - 3-dimensional i (3D) VT enables to quantitatively reconstruct object shapes with an accuracy of 0.5mm. 45/45