Notch size effect on DHC test using CB specimen of Zr-.2.5Nb pressure tube

Since it is not easy to make the pre-fatigue crack of CB(cantilever beam) specimen to carry out the DHC(Delayed Hydride Cracking) test if Zr-2.5Nb pressure tubes, DHC tests have been generally performed using CB specimen without pre-fatigue crack. However, there is no any trail to validate these test results of DHC. Therefore, the aim of this study is to investigate the notch size effect on DHC test using CB specimens in which 60 ppm hydrogen has been absorbed and heat-treated. In conclusion, while the DHCV result of CB specimen (notch radius 0.1 mm) made a good agreement with that of prefatigue specimen, DHCV results form CB specimens (notch radius >0.1 mm) showed the test uncertainty. In addition, it was found that the incubation time was increased with the increasing of notch radius and that the CB specimens with pre-fatigue crack should be used for DHC test to obtain KIH