Premature aging of the heat exchange tubes in steam generators due to stress corrosion may be a common cause of nonsimultaneous multiple ruptures, enhancing the risk associated with that accidental situation. Classical methods for probabilistic evaluation are not easily applicable to this type of problem. The component lifetime can be used directly as a primary random variable with a distribution width (mean value irrelevant) deduced from operational data or engineering judgment. The conditional probability to get one or more ruptures before a critical time following the occurrence of the first rupture can be obtained from the probability laws for the time intervals between the first and successive ruptures and can be used in accident sequence analyses. As an example, the conditional probability of the second rupture is approximately proportional to the critical time and is ∼10−4 for a lifetime distribution standard deviation of 15 000 h and a critical time of 1 h.