Given that an increasing number of nuclear facilities are entering their decommissioning period, the last 10 years have seen a dramatic rise in interest in reactor shutdown safety when the spent fuel is still in the reactor core. There is a vast amount of literature on the thermal analysis for the integrated pool, which includes the upper cavity and the spent fuel pool; however, little research has been conducted on how transients affect the safety of the reactor pressure vessel (RPV).

The aim of this paper is to evaluate the structural integrity of a RPV at a nuclear power plant during the transition to decommissioning using the probabilistic fracture mechanics method. Two thermal-hydraulic transients, which can occur after shutdown, were employed as loading conditions to calculate the conditional probabilities of initiation and failure of the RPV. The findings suggest that the effect of the transients on the probability of vessel failure is not significant. The author of this study contends that fuel damage is a relatively more important safety consideration during the shutdown transition period.