Session: MF-12-01 Materials and Fabrication: General Topics I

Paper Number: 62233

Start Time: Wednesday, July 14, 2021, 05:00 PM

62233 - Pilot Study on Seismic Fragility Evaluation for Degraded Austenitic Stainless Steel Piping Using the Probabilistic Fracture Mechanics Code PASCAL-SP 

Seismic probabilistic risk assessment is a standard methodology to quantify the risk of earthquakes including beyond-design-basis levels. Seismic probabilistic risk assessment mainly consists of three processes: seismic hazard analysis, fragility analysis, and sequence analysis. Seismic fragility represents the failure probabilities and the associated uncertainties of structures, systems, and components for a given level of seismic ground motion. 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 probabilities at the weld of an austenitic stainless steel pipe were evaluated on the basis of probabilistic fracture mechanics, which are widely used to evaluate rupture probability of piping systems. 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.

Presenting Author: Kisaburo Azuma Nuclear Regulation Authority, Japan

Authors:

Kisaburo Azuma Nuclear Regulation Authority, Japan
Yoshihito Yamaguchi Nuclear Safety Research Center, Japan Atomic Energy Agency
Yinsheng Li Nuclear Safety Research Center, Japan Atomic Energy Agency (JAEA)