Pilot study on seismic fragility evaluation for degraded austenitic stainless steel piping using the probabilistic fracture mechanics code PASCAL-SP

Azuma, Kisaburo*; Yamaguchi, Yoshihito ; Li, Y. 

Seismic probabilistic risk assessment is a standard methodology to quantify the risk of earthquakes including beyond-design-basis levels. The quality of fragility analysis is one of the major factors that affect the results of seismic probabilistic risk assessments. A previous study revealed that component degradation could affect seismic fragility. In practice, inspection and maintenance programs are implemented to control an undesirable effect of the degradation such as stress corrosion cracking. However, the relation between seismic fragility of degraded component and inspection, maintenance, and mitigation models has not been thoroughly discussed so far. This study discussed the effect of inspection and maintenance on seismic fragility of austenitic stainless steel piping susceptible to stress corrosion cracking. Failure probability was calculated by using a probabilistic fracture mechanics code. The results indicated that the adverse effects of stress corrosion cracking on failure probability could be controlled at a relatively low level if inspection, maintenance, and mitigation measures were implemented properly.