Estimation of CDF Considering the Degradation Effect of the Condensate Storage Tank

This paper presents a part of the research results of the 5-year BNL-KAERI collaboration program, the goal of which is to develop a realistic seismic risk evaluation system which includes the consideration of aging of structures and components in nuclear power plants (NPPs). A condensate storage tank (CST) located at the Ulchin NPP of Korea was selected to demonstrate the methodology. In U.S. NRC Regulatory Guide (RG) 1.174, Rev. 2, 'An Approach for Using Probabilistic Risk-Informed Decisions on Plant- Specific Changes to the Licensing Basis,' defines the acceptable level of changes of NPP in terms of risk, i.e., the core damage frequencies (CDFs). Hence, in this paper, we performed the probabilistic safety assessments to obtain the CDFs for a series of fragility capacities of degraded CST