Abstract: Based on operation experience of different tube materials, the rupture frequency was analyzed for 690TT and thermally treated tube (including 600TT and 690TT), taking Jeffreys as the prior distribution, accounting the total tube critical years to distinguish the steam generator tube numbers of different plants. The steam generator tube rupture (SGTR) initiating event frequency calculated in this way can appropriately display the decreasing impact and contribution of containment bypass failure risk induced by SGTR through improvement of tube material performance. Comparing with the frequency from generic database, it’s much lower and it will be even lower as the 690TT tube operation experience extends.