[2C01-08] Decommissioning Technology for Fukushima 1

[2C07] Piping system, risk management based on wall thinning monitoring and prediction - PYRAMID -

(5)Roughness measurement based on frequency analysis of ultrasonic wave reflected on rough surface

*Hiroyuki Nakamoto^1,3, Philippe Guy², Toshiyuki Takagi^3,4, Tetsuya Uchimoto^3,4 (1. Kobe Univ., 2. INSA de Lyon, 3. Tohoku Univ., 4. ELyTMaX UMI 3757)

Keywords:Nondestructive measurement, ultrasonic wave, attenuation, corrosion

Liquid flow in a pipe occurs corrosion on the inner surface. The corrosion reduces the thickness of the pipe and also forms a rough surface. In general, inspection for a pipe measures the thickness of the pipe to evaluate its health. The roughness of the inner surface is another factor. This study aims to the measurement of the rough surface of the pipe inner wall. The measurement device is an ultrasonic probe. An ultrasonic wave that is transmitted on the outer surface of the pipe reflects on the inner surface. The probe detects the reflected wave. If the inner surface has roughness, the ultrasonic wave scatters in the reflection on the rough wall. This study proposes a method of roughness measurement based on the ultrasonic attenuation. This paper shows the relationship between the attenuation and the roughness by frequency analysis and discusses the potential of the proposed method.