The effects of the stainless steel cladding in pressurized thermal shock evaluation

Fracture mechanics analysis is the key element of the integrity evaluation of the nuclear reactor pressure vessel (RPV), such as the pressurized thermal shock (PTS) analysis and P– T limit curve construction. However, the existence of stainless steel cladding, with different thermal, physical, and mechanical property at the inner surface of reactor pressure vessel complicates the fracture mechanics analysis. In this paper, the simple analytical treatment schemes to calculate the stress and resulting stress intensity factor at the tip of the flaws in the RPV with stainless steel cladding are introduced. For a reference thermal–hydraulic boundary condition, the effects of cladding thermal conductivity and thermal expansion coefficients on the stress intensity factor of surface flaws were examined. Also, the effects of cladding plasticity and thickness were quantitatively examined. The analysis results showed that the existence of the stainless cladding had significant impacts on the RPV failure probabilities.