Laser-ultrasonic study of micro crack sizing and its application to nuclear reactor internals
Laser-ultrasonic study of micro crack sizing and its application to nuclear reactor internals
著者:
Makoto OCHIAI Takahiro MIURA Satoshi YAMAMOTO Toru ONODERA
発刊日:
公開日:
bottom-mounted instrumentationcrack sizinglaser peeninglaser-ultrasonicsnon-destructive testingpreventative maintenancestress corrosion crackingsurface acoustic wave
概要
A new method for non-destructive testing（NDT）of surface-breaking tight cracks based on laser-induced surface acoustic waves（SAW）is proposed. A Q-switched Nd:YAG laser is used to generate SAW through ablative interaction between material and laser pulse. The SAW is probed by an optical interferometer as a micro displacement of the surface. A state-of-the-art technique in laser- ultrasonic NDT is developed: that is the crack depth measurement by using frequency analysis of laser-induced SAW transmitted through cracks. The technique allows measuring a depth of the surface-breaking tight crack ranging 0.5-1.5 mm with the standard deviation of 0.2 mm. Performance of this crack sizing technique on stress corrosion cracking（SCC）having depths of around 1 mm, are demonstrated. Also, the laser-ultrasonic NDT system developed for the inner surface inspection of bottom-mounted instrumentation（BMI）inpressurized water reacto（r PWR）and its mock-up results are introduced.
