Deterministic and probabilistic analysis of a reactor pressure vessel subjected to pressurized thermal shocks

• Deterministic and probabilistic methods are used to analyze a reactor pressure vessel.
• Assuming shallower cracks can be more conservative than assuming deeper ones.
• Master Curve methods are implemented in FAVOR for fracture toughness analysis.
• Master Curve method is more realistic in modeling fracture toughness.
• Warm prestressing effect decreases failure probability significantly.

Both deterministic and probabilistic methods are used to analyze a reference reactor pressure vessel (RPV) subjected to pressurized thermal shocks (PTSs). The FAVOR code was applied to calculate the probabilities for crack initiation and failure of a RPV subjected to two PTS transients, by considering different crack types, sizes and orientations. The Master Curve methods are implemented in the FAVOR code for a more realistic consideration of fracture toughness of the irradiated RPV.The analysis shows that a postulated underclad crack is the most conservative crack assumption. Assuming shallower cracks can be more conservative than deeper ones due to the fact that both KI and KIC at the crack tip increase with crack depth. Considering the warm prestressing effect (WPS) reduces the failure probability by more than two orders of magnitude.In this analysis, the FAVOR model for the calculation of fracture toughness is more conservative than the Master Curve method. But the Master Curve method is more realistic than the FAVOR model and thus its application is recommended.