PROBABILISTIC ENVIRONMENTALLY ASSISTED CRACKING MODELING FOR PRIMARY WATER STRESS CORROSION CRACKING OF ALLOY 600

Environmentally assisted cracking(EAC) has been studied intensively for several decades, but its mechanisms have not been understood due to the difficulty in crack detection. Therefore it is necessary to predict the cracking behavior using probabilistic estimation. In this study, Probabilistic EAC(PEAC) model is developed and the model is applied to the primary water stress corrosion cracking(PWSCC) of Alloy 600, which is one of the severe EAC problems. In the PEAC modeling, Bayesian parameter updating technique is applied to decrease the uncertainty of parameters by considering the probability of detection. According to this model, it is possible to predict crack growth rate and crack distribution and its results can be comparable with real data. The probability of failure is estimated from developed failure criteria. And the results from this study are applied to estimate the risk reduction by adopting RI-ISI in a PWR.