【公開日：2024.07.25】【最終更新日：2024.05.28】
課題データ / Project Data
課題番号 / Project Issue Number
23TU0087
利用課題名 / Title
内面溝付ダイバータ冷却管の接合界面検査に対する高周波超音波の適用性評価
利用した実施機関 / Support Institute
東北大学 / Tohoku Univ.
機関外・機関内の利用 / External or Internal Use
内部利用（ARIM事業参画者以外）/Internal Use (by non ARIM members)
技術領域 / Technology Area
【横断技術領域 / Cross-Technology Area】（主 / Main）加工・デバイスプロセス/Nanofabrication（副 / Sub）計測・分析/Advanced Characterization
【重要技術領域 / Important Technology Area】（主 / Main）その他/Others（副 / Sub）-
キーワード / Keywords
Copper-based alloy, Surface and Interface, 超音波顕微鏡/ Ultra-sonic microscope
利用者と利用形態 / User and Support Type
利用者名（課題申請者）/ User Name (Project Applicant)
ファリダフシン モハンマドジャバド
所属名 / Affiliation
東北大学大学院工学研究科
共同利用者氏名 / Names of Collaborators in Other Institutes Than Hub and Spoke Institutes
ARIM実施機関支援担当者 / Names of Collaborators in The Hub and Spoke Institutes
利用形態 / Support Type
（主 / Main）機器利用/Equipment Utilization（副 / Sub）-
利用した主な設備 / Equipment Used in This Project
報告書データ / Report
概要（目的・用途・実施内容）/ Abstract (Aim, Use Applications and Contents)
The purpose of this project was to investigate the applicability of high-frequency ultrasonic testing to inspect the bonded interface between the divertor's mono-block and the screw pipe in a nuclear fusion reactor. Grooved bonded samples simulating the bonded interface were analyzed using the インサイト IS-350 ultrasonic microscope. The effect of grooves' geometry on the performance of the tests to detect a defect at the interface was analyzed and then, design modifications were proposed to improve the performance. Because the screw pipe is one of the candidates to be used in the future generation of the nuclear fusion reactors, the results of this project can help the design teams to improve the capability of the screw pipe to be inspected with high-frequency ultrasonic testing.
実験 / Experimental
The samples used in this study consisted of a tungsten (W) block bonded to an oxygen-free copper (OFCu) plate to simulate the bonded interface between the mono-block and the screw pipe. Before fabricating the interface, a hole was drilled on the center of the W side, to represent a defect at the interface. Grooves were machined on the OFCu side after fabricating the bond. The ultrasonic tests were performed from the OFCu side before and after fabricating the grooves, using probes with frequencies from 5 MHz to 50 MHz in the pulse-echo immersion technique. The probes scanned the samples two-dimensionally in a 40 mm by 40 mm grid with 0.1 mm steps. The speeds of sound for water and copper were set to 1480 m/s and 4660 m/s respectively.
結果と考察 / Results and Discussion
A schematic of the high-frequency ultrasonic testing of the grooved samples and the time-of-flight of the echoes reflected from the surface of the sample and the W-OFCu interface is shown in Figs. 1 and 2. The time-of-flights of Table 1 are calculated according to Eq. 1. Figures 3 and 4 contain schematics of the sample with and without grooves, and as shown in Fig. 4 the left and right halves of the sample contain grooves of the original design of the screw pipe and with step-like geometry. The ultrasonic images of the first and second echoes of the layer containing the W-OFCu interface obtained from the sample without grooves are shown in Figs. 5 and 6, and the drilled hole at the interface can be observed. However, as shown in Figs. 7 and 8, the visibility of the hole in ultrasonic images is considerably reduced in both the first and second echoes after the grooves were machined on the surface of the sample. After analyzing the effect of grooves' geometrical parameters on the performance of high-frequency ultrasonic tests, it was found out that the original screw pipe design has a low capability to be inspected with high-frequency ultrasonic testing. The geometrical parameters of the grooves were the grooves' angle, grooves' height, and the length of the flat surfaces of the grooves. The angle of the slope of the grooves in the original screw pipe design is less than the critical angle calculated by the Snell's law; therefore, ultrasonic waves will be totally reflected from the grooves and the defects under the slope will be undetected. Moreover, the height of the grooves in the original design of the screw pipe will cause the ultrasonic echoes reflected from the surface of the grooves to interfere with the echoes from the W-OFCu interface. In addition, the flat surfaces of the grooves were found to have a small effect on the defect detection performance of the tests. It was proposed to change the groove angle to zero, which means to have step-like grooves, and to change the height of the grooves to prevent echo interference. The high-frequency ultrasonic testing results showed that the proposed modifications considerably improve the detection performance of the tests.
図・表・数式 / Figures, Tables and Equations
Fig. 1. Schematic of the ultrasonic echoes reflected from the samples with grooved surface
Fig. 2. Time-of-flight of the ultrasonic echoes shown in Fig. 1.
Table. 1. Time-of-flight values of the echoes shown in Fig. 2
Eq. 1. Time of flight
Fig. 3. Schematic of the sample without grooves
Fig. 4. Schematic of the sample with two groove geometries on its surface
Fig. 5. Ultrasonic image of the sample without grooves, with time of flight t3
Fig. 6. Ultrasonic image of the sample without grooves, with time-of-flight t5
Fig. 7. Ultrasonic image of the sample with grooves, with time-of-flight t4
Fig. 8. Ultrasonic image of the sample with grooves, with time-of-flight t6
その他・特記事項（参考文献・謝辞等） / Remarks(References and Acknowledgements)
成果発表・成果利用 / Publication and Patents
論文・プロシーディング（DOIのあるもの） / DOI (Publication and Proceedings)
口頭発表、ポスター発表および、その他の論文 / Oral Presentations etc.
- M. Faridafshin, N. Yusa, W. Chen, “High-frequency ultrasonic inspection of the divertor’s cooling pipe with a screwed inner wall”, 21st International Symposium on Applied Electromagnetics and Mechanics, Hachioji, Tokyo, November 2023.
特許 / Patents
特許出願件数 / Number of Patent Applications：0件
特許登録件数 / Number of Registered Patents：0件