TY - GEN
T1 - Time-Dependent Fragility Curves for SSCs
T2 - 18th International Probabilistic Safety Assessment and Analysis, PSA 2023
AU - Batikh, Akram S.
AU - Dhulipala, Somayajulu L.N.
AU - Spencer, Benjamin W.
AU - Dahal, Albert
AU - Diaconeasa, Mihai A.
N1 - Funding Information:
We greatly appreciate an overall acknowledgment of the funding support provided by the U.S. Department of Energy’s EHSS NSR&D Program managed within the Office of Nuclear Safety.
Publisher Copyright:
© 2023 Proceedings of 18th International Probabilistic Safety Assessment and Analysis, PSA 2023. All Rights Reserved.
PY - 2023
Y1 - 2023
N2 - The consideration of external multi-hazards in probabilistic risk assessments (PRAs) for nuclear power plants (NPPs) has become a necessity after the Fukushima Daiichi accident in 2011. However, a comprehensive PRA framework that incorporates all possible external multi-hazards is yet to be developed. In our current research path, we aim at developing a multi-hazard time-dependent PRA approach that considers the aging-related deterioration of structures. A generic pressurized water reactor (PWR) reactor subjected to seismic mainshock-aftershock (MS-AF) sequences was considered as a case study to demonstrate the multi-hazard PRA approach. We propose a methodology for integrating aftershock sequences in conventional seismic PRAs to support multi-hazard analysis. The triggering probability for aftershocks was based on the modified Omori Law. A seismic Equipment list (SEL) was developed based on NRC’s guidance and industry practice. We applied the new framework to three levels of plant systems: component-level, system level and plant-level. For component and systems level, we obtained the time-dependent fragility curves with their associated uncertainties, calculated by applying the Latin Hypercube Monte Carlo Method (LHS) while marching along the peak ground acceleration (PGA) axis. The results indicate a rise in the failure probability of SSCs with time, especially in lower PGA bins. For a plant-level analysis, a seismic event tree was quantified to get the time-dependent fragility function. The results show a significant increase in the probability of failure, particularly with the median value, which exhibits a two-order-of-magnitude rise.
AB - The consideration of external multi-hazards in probabilistic risk assessments (PRAs) for nuclear power plants (NPPs) has become a necessity after the Fukushima Daiichi accident in 2011. However, a comprehensive PRA framework that incorporates all possible external multi-hazards is yet to be developed. In our current research path, we aim at developing a multi-hazard time-dependent PRA approach that considers the aging-related deterioration of structures. A generic pressurized water reactor (PWR) reactor subjected to seismic mainshock-aftershock (MS-AF) sequences was considered as a case study to demonstrate the multi-hazard PRA approach. We propose a methodology for integrating aftershock sequences in conventional seismic PRAs to support multi-hazard analysis. The triggering probability for aftershocks was based on the modified Omori Law. A seismic Equipment list (SEL) was developed based on NRC’s guidance and industry practice. We applied the new framework to three levels of plant systems: component-level, system level and plant-level. For component and systems level, we obtained the time-dependent fragility curves with their associated uncertainties, calculated by applying the Latin Hypercube Monte Carlo Method (LHS) while marching along the peak ground acceleration (PGA) axis. The results indicate a rise in the failure probability of SSCs with time, especially in lower PGA bins. For a plant-level analysis, a seismic event tree was quantified to get the time-dependent fragility function. The results show a significant increase in the probability of failure, particularly with the median value, which exhibits a two-order-of-magnitude rise.
KW - Aftershocks
KW - Multi-Hazard
KW - PRA
KW - Seismic Analysis
KW - Seismic Fragility
UR - http://www.scopus.com/inward/record.url?scp=85184353722&partnerID=8YFLogxK
U2 - 10.13182/PSA23-41058
DO - 10.13182/PSA23-41058
M3 - Conference contribution
AN - SCOPUS:85184353722
T3 - Proceedings of 18th International Probabilistic Safety Assessment and Analysis, PSA 2023
SP - 910
EP - 919
BT - Proceedings of 18th International Probabilistic Safety Assessment and Analysis, PSA 2023
PB - American Nuclear Society
Y2 - 15 July 2023 through 20 July 2023
ER -