Flaw depth evaluation of primary water stress corrosion cracking in steam generator tubing

Flaw depth evaluation was performed on the priamry water stress corrosion cracking in steam generator tubing, with the eddy current test results such as signal amplitude and phase angle. The relationship between crack length and crack depth was also investigated, based on the metallogrphic results of pulled-out tubings. This study yields the following results and conclusions: (1) there is no correlation between crack length and crack depth. (2) it is not easy to correlate the crack depth with phase angle. (3) although signal amplitude appears to be related with crack length, the latter cannot exactly be obtained from the former value. (4) since most cracks with the length above 6 mm could be a through-crack, it would be helpful to plug that tubing in order to prevent tube-leaking