Cleavage Fracture Analysis of Cladded Beams With an Embedded Flaw Under Four-Point Bending

Abstract

Semi-large scale embedded flaw beams were tested at Nuclear Research Institute (NRI) Rez in the Czech Republic for the 6th Network for Evaluating Structural Components (NESC_VI) project. The experiments included, among others, a series of semi-large scale tests on cladded beam specimens containing simulated sub-clad flaws. Oak Ridge National Laboratory (ORNL) conducted numerical studies to analyze the constraint issues associated with embedded flaws using various fracture mechanics methods, including T-Stress, hydrostatic stress based QH stress, and the Weibull stress model. The recently developed local approach using the modified Weibull stress model combined with the Master Curve methodology was also utilized to predict the failure probability (Pf) of semi-large scale beams. For this study, the Weibull statistical model associated with the Master Curve methodology was employed to stochastically simulate the fracture toughness data using the available Master Curve reference temperature T0 for the tested base material from the “aged” WWER-440 Reactor Pressure Vessel (RPV). The study was also conducted to investigate the sensitivity of predicted probability of failure of semi-large scale beams with embedded flaw with different Weibull shape parameters, m.