The effects of thermal stresses on the elliptical surface cracks in PWR reactor pressure vessel

• The SIFs are provided as a reference tool for fracture mechanics design of the RPV.
• The Westinghouse RPV made of SA-533 Gr.B, Cl.1 steel is a safe design.
• The application of the annular chamber is fully successful and safe.

In this study, the effects of thermal stresses on the stress intensity factors (SIFs) of the elliptical corner surface cracks postulated at the nozzle-cylinder intersection of a reactor pressure vessel (RPV) were investigated. A typical RPV of a Westinghouse pressurized water reactor and its set-in nozzle were considered for the analysis. The selected set-in nozzle-cylinder intersection for fracture mechanics analysis is also the highest stress concentration point of the RPV. The numerically computed SIFs for a wide range of corner cracks under pressure and combined (pressure plus thermal) loadings are provided as a reference tool for the fracture mechanics design of the RPV. It was also demonstrated that the operational thermal stresses caused by the provision of the annular chamber for the external reactor vessel cooling, actually reduce the SIF of the corner cracks and they do not endanger the safety of the RPV in normal operating conditions.