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OTs > JP2 > Day 1 - Day 2 (A1 - A2 - B1 - B2 - C1 - C2 - E1- E2 - E3 - F3)- Day 3
Japan Column
August 17, 2010 (Last update: Dec. 28, 2010)
JSM 7th Annual Conference at Omaezaki, Shizuoka

Day Two (July 14, 2010)

[A-2] Nondestructive Evaluation (NDE)

Chair: Ichiro KOMURA (JAPEIC), Ju YANG (Nagoya Univ.)and Yoshihiro MATSUMOTO (NELTD)

Some of the most important maintenance technologies such as Ultrasonic Testing, Eddy Current Testing, and Electromagnetic Evaluation, were introduced in this session.


Characteristic of Ultrasonic Wave Propagation on a Flat Plate and a Spherical Plate

Hitoshi ISHIDA (Institute of Nuclear Safety System, Incorporated (INSS))

A purpose of this study is evaluation and determination of specifications of ultrasonic testing system for a large component for which it is difficult to develop UT system with a mock-up. We have tried to evaluate elastic wave intensity with elastic wave propagation finite element analysis for a flat plate.

This study reports characteristic of ultrasonic wave propagation on a spherical plate by measurements of ultrasonic wave signal intensity and comparison with result with a flat plate.

Ultrasonic testing, ultrasonic wave, elastic wave, spherical plate, Quantitative Evaluation


Image-based Simulation of Wave Propagation and its Application to Ultrasonic Testing

Kazuyuki NAKAHATA (Ehime University) and Sohichi HIROSE (Tokyo Institute of Technology)

A straightforward simulation method is desired for the reliable nondestructive ultrasonic testing (UT). The target models for the UT become more complicated than ever, such as dissimilar welding parts in nuclear power plant or debonding parts of reinforced steels in concrete material. In this study, a time domain simulation tool for ultrasonic wave propagation in heterogeneous and anisotropic materials with a complex outer surface is developed by combining the elastodynamic finite integration technique (EFIT) with an image based modeling approach. The EFIT is a grid-based spatial discretization method in conjunction with the leap-frog time marching scheme. In our simulation, geometries of targets are determined by digital images from two dimensional(2D) pictures or three dimensional(3D) CT and CAD data.

Ultrasonic Simulation, Image-based Modeling, Elastodynamic Finite Integration Technique, Heterogeneous and Anisotropic Materials


Development of Phased Array Inspection Technique for Nozzle Pipes with Curved Surface


Inspection technique for complex surface profiles has been required in order to ensure the reliable operation and high operating rate of nuclear power plants, because many parts due to inspection have complex geometry. We have developed Phased Array (PA) ultrasonic testing with immersion technique which suitable to complex geometry. In this paper, we developed precise inspection technique for curvature surface profile such as a nozzle of pressure vessel. For curved surface profile, Synthesis Aperture Focusing Technique (SAFT) is adapted to measure surface profile, and delay time calculation code for not only curved surface but also free-formed surface is developed. In addition, reconstruction of inspection result by surface profile is also developed. Furthermore, we substitute water with immersion technique for developed gel which suitable to in air. Foregoing method we developed, inspection technique for curved surface and swell parts is achieved.

Ultrasonic, Phased Array UT, SAFT, Immersion Technique, Gel

Three-Dimensional Phased Array Ultrasonic Testing

So KITAZAWA, Naoyuki KONO, Atsushi BABA, Yuji ADACHI (Hitachi, Ltd.) and Mitsuru ODAKURA (Hitachi-GE Nuclear Energy, Ltd.)

Ultrasonic testing techniques by using the three-dimensional (3D) phased array was investigated. The 3D phased array allows a target region to be scanned volumetrically with focused beams transmitted from a matrix array probe. This leads to an increase in inspection speed and easy-to-understand inspection results displayed as 3D rendered images. This paper focuses mainly on synthesizing techniques of 3D scanned data obtained at multiple positions when moving the probe. The technique is effective to figure out positions and a distribution of reflectors more precisely.

Ultrasonic Testing, Phased Array, 3-Dimensional

Development of inspection method for thinned bolts by PA-UT

Hideki YUYA, Keisuke ITOU, Chiaki YAMAMOTO (CHUBU Electric Power Co., lnc.), Akihiro KAKO (CHUBU Plant Service Co., Ltd.), Takenari FUJIO, Satoru SHIROSHITA (Non-Destructive Inspection Company Limited.), Shan LIN, Hiroyuki FUKUTOMI (Central Research Institute of Electric Power Industry)

Many anchor bolts have been used for fixing many components in nuclear power plant (NPP), securing safety against seismic events. Some methods have been developed to detect crack-like defects in bolts which may occur after seismic events. On the other hand, assuming long term use of NPP, a method to detect bolt thinning was thought to be needed. In this study, by using bolt specimens with an artificially grinded portion, a new method to detect thinning and to measure its depth was developed.

Anchor bolt, Thinning, Inspection, Ultrasonic Test, Phased Array


Application of Phased Array UT Technique for Crack Depth Sizing on Nickel Based Alloy Weld

Taiji HIRASAWA, Hiroyuki FUKUTOMI (Central Research Institute of Electric Power Industry)

Recently, it is reported that the primary water stress corrosion cracking (PWSCC) has been occurred at the nickel based alloy weld components such as steam generator safe end weld, reactor vessel safe end weld, and so on, in PWR. Defect detection and sizing is important in order to ensure the reliable operation and life extension of nuclear power plants. In the reactor vessel safe end weld, it was impossible to measure crack depth of PWSCC. The crack has occurred in the axial direction of the safe end weld. Furthermore, the crack had some features such as shallow, large aspect ratio (ratio of crack depth and length), sharp geometry of crack tip, and so on. Therefore, development and improvement of defect detection and sizing capabilities for ultrasonic inspection technique have been required. Phased array technique was applied to nickel based alloy weld specimen with EDM notches. From the experimental results, the superior performance of phased array UT for the inside inspection was shown.

Ni Based Alloy Weld, Crack Depth Sizing, Phased Array UT, PWSCC


Development of the advanced phased array UT technique for accurate sizing of cracks in the nozzle welding

Jun-ichiro NISHIDA, Seiichi KAWANAMI, Mitsushi IDEO, Takayuki MATSUURA (Mitsubishi Heavy Industries, LTD.), Naoki CHIGUSA, Shinro HIRANO, Takehiko SERA (The Kansai Electric Power Co., INC. )

Recently, preventive maintenance tasks for welding of safe-end nozzles of reactor vessels and steam generators of PWRs in Japan had been carried out sequentially. Before the maintenance tasks, inspection services were carried out and several crack indications were found by eddy current testing (ECT). These indications were fund in the welding which made by 600 series nickel base alloy and evaluated as stress corrosion cracks which were oriented to the axial direction of the nozzle. Then investigations to evaluate the depth of cracks were carried out by ultrasonic testing (UT) from inner surface of the nozzles. However they were difficult to evaluate the depth of cracks due to the high attenuation of the ultrasonic propagation caused by large grain structure of welding. And also it was required high resolution near surface region for accurate sizing. Therefore development of advanced phased array UT techniques specialized for the sizing at this portion was carried out. This paper reports the development status and verification test results. Firstly simulations of the ultrasonic propagation in the welding were carried out to optimize beam profiles of phased array probes. Next prototype probes were manufactured and verification tests were conducted to evaluate the accuracy of depth sizing. It is shown that the developed techniques have high sizing accuracy for artificial stress corrosion cracks in the welding.

Ultrasonic Testing, Dissimilar Metal Welding, UT Sizing, Phased Array, Matrix Phased Array

Result of UT verification test for Stainless Steel through weld deposit

Yoshiaki NAGATA (The Chugoku Electric Power Co., Inc.), Katsuhiro HASEGAWA (Tohoku Electric Power Co., Inc.) Masakuni KUMEDA (The Tokyo Electric Power Company, Inc.) Tetsuhiko INAGAKI (CHUBU Electric Power Co., lnc.), Chikahide NAKADA (Hokuriku Electric Power Company), Takashi OHTA (The Japan Atomic Power Company) , Yutaka TAGUCHI (Electric Power Development Co.,Ltd.) , Yutaka KOMETANI, Yasushi SHIMIZU (Hitachi-GE Nuclear Energy, Ltd.), Tadahiro MITSUHASHI (TOSHIBA CORPORATION), Hajime SHOHJI (IHI Corporation), Atsunori YAMAGUCHI, Takuya SUGIBAYASHI, and Teruo KOBAYASHI (Japan Power Engineering and Inspection Corporation)

BWR owners and plant fabricators have been making efforts to decrease the ISI parts where UT is difficult to be conducted. For that purpose, UT verification test for both detection and sizing qualification through deposit of pipe weld joint started in 2009 and will last until 2011.

In 2009, UT verification test for stainless steel pipe weld joint has been performed. Test samples are stainless steel pipes with welds and sizes are 600A.350A.150A with EDM notches and/or SCCs. Angle beam methods and phased-array angle beam methods have been applied.

The detection test shows that there are no failure to detect and no false call. The length sizing test shows that RSM errors of SCC lengths are within the ASME acceptance criteria. So, it is clarified that each method has the enough qualification for UT through deposit of stainless steel pipe weld joint. These tests have been witnessed and evaluated by JAPEIC as the third body.

Ultrasonic Testing, Stainless steel, Stress Corrosion Cracking, Phased array UT


Applicability Evaluation of Eddy Current Testing for Underwater Laser Beam Welding


We clarified a defect detecting capability of eddy current testing (ECT) as a surface inspection technique for underwater laser beam welding. An underwater laser beam welding procedure includes groove caving as a preparation, laser beam welding in groove and welding surface grinding as a post treatment. Therefore groove and grinded welding surface inspections are required underwater. We curried out defect detection tests using three kinds of specimens simulated a groove, reactor vessel nozzle dissimilar metal welding materials and a laser beam welding material with a cross coil ECT probe. From experimental results, we confirmed that it is possible to detect 0.3 mm or more depth electro-discharge machining slits on machining surfaces in all specimens and an ECT has possibility as a surface inspection technique for underwater laser beam welding.

Eddy current testing, Defect detecting capability, Underwater laser beam welding, PWR, BWR

Surface Inspection Technique with an Eddy Current Testing Array Probe

Akira NISHIMIZU, Hisashi ENDO, Mahiro TOOMA (Hitachi, Ltd.), Kenichi OTANI, Hirofumi OUCHI, Isao YOSHIDA, Yoshio NONAKA (Hitachi-GE Nuclear Energy, Ltd.)

An eddy current testing (ECT) system has been developed for inspecting weld surfaces of components in the reactor pressure vessel of nuclear plants. The system can be applied to curved surfaces with an ECT array probe, it can discriminate flaws from other signal factors by using a combination of arrayed coils signal-phase. The system is applied to a mock-up of core internal components and the signal discrimination using the signal-phase clearly separated flaw and noise signals.

Surface Inspection Technique, Eddy Current Testing, Array Probe


Improvement of Magnetic Flux Density Measurement Technique for Irradiation Damage Evaluation

Shotaro KONNO, Shigeru TAKAYA, Yuji NAGAE, Ichiro YAMAGATA, Ryuichiro OGAWA, Naoaki AKASAKA, Kenji NISHINOIRI ( Japan Atomic Energy Agency (JAEA))

We are developing a method for evaluation of irradiation damage on structural materials in nuclear plants by using change in magnetic flux density due to irradiation damage. In this study, the magnetic flux density measurement technique has been improved by introducing a new magnetizer which enables local magnetizing by contacting the sample surface. We can magnetize samples, especially ferromagnetic samples, more precisely compared to the existing method. Furthermore, the new method can remove many limitations for the application to real plants. In addition, we established the calibration method of the flux gate sensor for the magnetic flux density. As a result, accuracy and the reliability of the measurement of the flux density became better, and also, the comparison with the result of the measurement with other flux gate sensors became possible.

Nondestructive Evaluation, Magnetic Property, Magnetizing Method, Flux Gate Sensor, Structural Materials, High-Chromium Steel, Neutron Irradiation, Calibration


Electromagnetic Nondestructive Detection for Wounded Bearings and Correlation of Size of Defect and Signal

Ryo KAYATA (IIU Corporation), Takemasa MIYOSHI, Hideki FUJIWARA (Shikoku Electric Power CO.,Inc.), Perrin STEPHANE (IIU Corporation)

A new electromagnetic method for the nondestructive evaluation of electric pumps with ball bearings is proposed. A permanent magnet generates a static magnetic field and a coil of several hundred turns wrapped around it is used to pick up eddy currents induced inside rotating ball bearings and impellers. First, a method that make use of the autocorrelation is applied to the signals of the ball bearings. A relation between the processed signals and the size of the defects in the bearings is obtained.

Electromagnetic Nondestructive Detection Method, Ball Bearings, Eddy Currents


Electromagnetic Nondestructive Detection for Monitoring the Damage Progress of Ball Bearings


This study evaluates the outer race defect size of ball bearings in the accelerated life test by analyzing the signal of electromagnetic sensor. The electromagnetic sensor consists of a permanent magnet and a pickup coil. When a conductor passes in the static magnetic field, the generated eddy current is detected as the change of the magnetic field. The autocorrelation method is applied for sizing defects in the early phase of the damage progress and the RMS method is developed for bigger defects. With those methods, the damage progress is visualized and the characteristic of it is revealed as almost linear.

electromagnetic nondestructive detection, ball bearing, signal procedure, accelerated life test


Electromagnetic evaluation of the impeller of a turbine using a high temperature superconductivity electromagnet

Haoyu HUANG, Kentaro TAKASE (IIU Corporation), Naoaki SHIBASHITA (Hitachi, Ltd.), Mitsuo KUGIMOTO (CHUBU Electric Power Co., lnc.), Toru TSUKAMOTO (Hokuriku Electric Power Company)

This study proposes an electromagnetic method for the evaluation of the condition of a turbine in a nuclear power plant. Experimental results of a small turbine driven by an electric motor are shown in this paper. A high temperature superconductivity electromagnet is applied outside the case of the turbine to provide excitation magnetic field. On the other hand, pickup coils are placed near the impeller inside the case of the turbine. The experimental results show that it is not only possible to detect the movement but also the condition of the impeller by applying the electromagnetic evaluation method. Moreover, an enforcement vibration experiment shows that the vibration increment as well as the main frequency of the vibration of the impeller can be detected when comparing the results of cases with and without enforcement excitation.

Electromagnetic Evaluation Method, Turbine, High Temperature Superconductivity Electromagnet.


Fig. 5 A discussion after a presentation on [A-2] "Nondestructive Evaluation (NDE)"

Proceedings of JSM 7th Annual Conference, p.41-p.106, Omaezaki, July 2010 (in Japanese).

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EJAM Japan Column "The JSM 7th Annual Conference: Nondestructive evaluation (NDE)"