Failure probability estimation for axial through-wall cracked steam generator tubes

Steam generator tubes in pressurized water reactor (PWR) are exposed to various types of degradation and aging processes which might significantly decrease its structural reliability. Up to now, integrity evaluations are performed by using conventional deterministic approaches. However, there are lots of uncertainties to perform a rational evaluation of lifetime. In this respect, a probabilistic safety assessment method is more appropriate for the assessment of overall steam generator tube safety. The objective of this study is to estimate the failure probability of steam generator tubes containing a single through-wall cracks. Major input variables such as crack length, yield strength and ultimate tensile strength are considered as probabilistic variables. A limit load solution is used to constitute a limit state function. In the analyses, failure probabilities are calculated by using the FORM (First Order Reliability Method), SORM (Second Order Reliability Method), and MC (Monte Carlo) simulation method