Stress intensity factors of corner cracks at set-in nozzle–cylinder intersection of a PWR reactor pressure vessel

Reactor pressure vessel (RPV) is the central and the most important component of a pressurized water reactor (PWR). The fracture mechanics analysis of different parts of the RPV under various loading conditions is compulsory as it is not always possible to manufacture a crack- or defect-free component. The strength of a crack, in an engineering component, is normally evaluated by computing the stress intensity factors (SIFs) along the crack front. In this paper, for the fracture mechanics analysis of the set-in nozzle of a 300-MW RPV, the SIFs of a wide range of corner surface cracks at the nozzle–cylinder intersection are being presented. The considered RPV is made of a nuclear-grade steel designated as ‘SA-508 Gr.3 Cl.1’. The analyzed corner cracks are in the range of ‘0.01 < a/t < 0.25’ and ‘0.33 < a/c < 1.0’, where ‘a’ and ‘c’ represent minor and major axes of the crack, respectively; and ‘t’ is the thickness of the vessel wall at the nozzle–cylinder intersection. In this study, both the linear elastic fracture mechanics (LEFM) and elasto-plastic fracture mechanics (EPFM) based SIFs are provided under normal operating conditions of the plant. The shape and size of the plastic zone at the crack tip, using von Mises failure criterion, is also presented.