Abstract This paper describes a new crack tip diffraction approach using a set of angle beam and direct contact transducers. In this approach, a crack height is calculated from a time di fference from two echoes of a tip-diffracted longitudinal wave, which arise after an incident wave from the angle beam transducer impinges the crack. The two echoes are detected by the d irect contact transducer which lies on the opposite surface of and over the crack. One echo is related to the wave traveling directly fro...
英字タイトル:
Proposal of Concise Crack Sizing Approach in Ultrasonics

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 wel...
英字タイトル:
Application of Phased Array UT Technique for Crack Depth Sizing on Nickel Based Alloy Weld

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 reli able 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 was detected in the axial direction of the safe end wel...
英字タイトル:
Development of Phased Array UT procedure for Crack Depth Sizingon Nickel Based Alloy Weld

Recently, it is reported that the primary water stress corrosion cracking (PWSCC) has been occurred at the nickel based alloy weld components such as stea m 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 operat ion 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 was dete cted in the axial direction of the safe end w...
英字タイトル:
Investigation of Phased Array UT procedure for Crack Depth Sizing on Nickel Based Alloy Weld

Many anchor bolts have been used for fixing many components in nuclear power plant (NPP), securing safety against seismic ev ents. Some methods have been developed to detect crack-like defects in bolts which may occur after seismic events. On the ot her 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....
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Development of inspection method for thinned bolts by PA-UT

国内の電気事業においては既に電力流通設備に対する点検にドローンが導入され始めている。そして、火力発電設備への点検でも活用しようという機運が高まっている。ボイラや煙道内などでの近接目視点検では、壁面の近傍を安全に飛行できるとともに、撮影した写真ごとに一画素当たりの寸法を揃えるにはドローンに積載されたカメラの撮影距離、すなわちドローンと壁面の距離を一定に保つ必要があり、作業効率からその状態で上下左右に操縦できる機能が望まれている。 当所では、先行事例を参考に 2個のレーザ距離計、シングルボードコンピュータおよびドローンのソフトウェア開発キット（Software Development Kit, SDK）などを用い、壁面に対するドローンの向きと距離を制御するための飛行制御用モジュールを試作した。そして、2個のレーザ距離計を 360 °方向の距離を測定するレーザスキャナに置き換え、暗所においても有効な衝突回避機能を追加した。本稿では、 2019年時点での飛行制御用モジュールとその動作確認結果について述べる。...

In recent years, it has been reported that the primary water stress corrosion cracking (PWSCC) has occurred in dissimilar metal weld (DMW) components such as steam generator safe end weld, reactor vessel safe end weld, and so on, in PWR. The depth sizing of such cracks with high accuracy is important in order to ensure the reliable operation and life extension of nuclear power plants. Therefore, construction of the performance demonstration (PD) system for certifying DMW inspection method is being inve...
英字タイトル:
Investigation of Phased Array UT technique for Circumferential Crack Depth Sizing in Dissimilar Metal Weld

In order to determine crack depth in primarily loop recirculation (PLR) piping of boiling water reactors, ultrasonic angle beam testing using time of flight measurement of the diffracted signal from the crack tip, is employed. There are some power stations in Japan having saddle-shaped weld joints at branch connections in PLR piping. If the angle beam testing is applied without considering curvature of saddle-shaped weld joints, unlike weld joints of straight piping, it can be predicted that determine...
英字タイトル:
Ultrasonic Depth-sizing Errors of Crack-like Defects in Saddle-shaped Weld Joints