Plasma and Fusion Research

Volume 18, 2405068 (2023)

Regular Articles

The Effect of the Grain Size of Divertor's Cooling Pipe on the Capability of High-Frequency Ultrasonic Tests to Evaluate the Quality of the Bond between Divertor's Cooling Pipe and Armor

Mohammadjavad FARIDAFSHIN, Noritaka YUSA, Ryouji SUZUKI¹⁾, Takashi FURUKAWA¹⁾, Masayuki TOKITANI²⁾ and Suguru MASUZAKI²⁾

: Department of Quantum Science and Energy Engineering, Graduate School of Engineering, Tohoku University, 6-6-01-2 Aramaki Aza Aoba, Aoba-ku, Sendai, Miyagi 980-8579, Japan
1): Nondestructive Evaluation Center, Japan Power Engineering and Inspection Corporation, 14-1 Benten-cho, Tsurumi-ku, Yokohama, Kanagawa 230-0044, Japan
2): National Institute for Fusion Science, 322-6 Oroshi, Toki, Gifu 509-5292, Japan

(Received 5 January 2023 / Accepted 2 July 2023 / Published 10 August 2023)

Abstract

This study evaluated the effect of the grain size of the divertor's cooling pipe on the capability of high-frequency ultrasonic tests to evaluate the quality of the bonded interface between the divertor’s cooling pipe and armor. First, simple oxygen-free copper and copper-chromium-zirconium block samples with different grain sizes were prepared and measured by an ultrasonic microscope with a 35 MHz probe. The results of the measurements confirmed that the non-uniformity of backwall echoes increased with the grain size of the samples. Samples with large grains provided distinctive signals that can be clearly confirmed on the ultrasonic C-scan images. Subsequently, two bonded samples consisting of 2.5 mm oxygen-free copper bonded with a block of pure tungsten that meets the material specifications of tungsten for ITER component which mimicked the basic design of a divertor's cooling pipe and a monoblock, were measured to evaluate their bonded interfaces. One of the bonded samples bonded at a high temperature provided distinctive signals due to the enlargement of the grain of the oxygen-free copper. Results confirmed that the grain enlargement is the reason for reduced defect detection capability of the high-frequency ultrasonic tests as was suggested previously. This study also revealed that the enlargement of grain caused by improper manufacturing would be non-destructively detectable by high-frequency ultrasonic tests.

Keywords

nuclear fusion reactor, non-destructive inspection, bonded interface, diffusion bonding, heat treatment

DOI: 10.1585/pfr.18.2405068

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References

[1] G. Mazzone et al., Fusion Eng. Des. 157, 111656 (2020).
[2] G. Pintsuk et al., Fusion Eng. Des. 174, 112994 (2022).
[3] J.H. You et al., Fusion Eng. Des. 175, 113010 (2022).
[4] J.H. You et al., J. Nucl. Mater. 544, 152670 (2021).
[5] M. Richou et al., Physica Scripta 2017, 014022 (2017).
[6] J.H. You, et al., Fusion Eng. Des. 164, 112203 (2021).
[7] S. Roccella et al., Fusion Eng. Des. 146, 2356 (2019).
[8] G. Dose et al., Fusion Eng. Des. 146, 870 (2019).
[9] N. Yusa et al., Plasma Fusion Res. 17, 2405013 (2022).
[10] N. Yusa et al., Fusion Eng. Des. 187, 113367 (2023).
[11] S. Hirsekorn, J. Acoust. Soc. Am. 72, 1021 (1982).
[12] E.P. Papadakis, J. Acoust. Soc. Am. 33, 1616 (1961).
[13] M. Norouzian et al., Ultrasonics 102, 106032 (2020).
[14] A. Van Pamel et al., J. Acoust. Soc. Am. 143(4), 2394 (2018).
[15] A.P. Arguelles and J.A. Turner, J. Acoust. Soc. Am. 141, 4347 (2017).
[16] E. Tejado et al., J. Nucl. Mater. 498, 468 (2018).
[17] M. Wirtz et al., Nucl. Mater. Energy 12, 148 (2017).
[18] E. Tejado, Mater. Sci. Eng. A 712, 738 (2018).