Seismic Fragility Analysis of a Degraded Condensate Storage Tank
The Korea Atomic Energy Research Institute (KAERI) and Brookhaven National Laboratory are conducting a collaborative research project to develop seismic capability evaluation technology for degraded structures and components in nuclear power plants (NPPs). One of the goals of this collaboration endeavor is to develop seismic fragility analysis methods that consider the potential effects of age-related degradation of structures, systems, and components (SSCs). The essential part of this collaboration is aimed at achieving a better understanding of the effects of aging on the performance of SSCs and ultimately on the safety of NPPs. A recent search of the degradation occurrences of structures and passive components (SPCs) showed that the rate of aging related degradation in NPPs was not significantly large but increasing, as the plants get older. The slow but increasing rate of degradation of SPCs can potentially affect the safety of the older plants and become an important factor in decision making in the current trend of extending the operating license period of the plants (e.g., in the U.S. from 40 years to 60 years, and even potentially to 80 years). The condition and performance of major aged NPP structures such as the containment contributes to the life span of a plant. A frequent misconception of such low degradation rate of SPCs is that such degradation may not pose significant risk to plant safety. However, under low probability high consequence initiating events, such as large earthquakes, SPCs that have slowly degraded over many years could potentially affect plant safety and these effects need to be better understood. As part of the KAERI-BNL collaboration, a condensate storage tank (CST) was analyzed to estimate its seismic fragility capacities under various postulated degradation scenarios. CSTs were shown to have a significant impact on the seismic core damage frequency of a nuclear power plant. The seismic fragility capacity of the CST was developed for five cases: (1) a baseline analysis where the design condition (undegraded) is assumed, (2) a scenario with degraded stainless steel tank shell, (3) a scenario with degraded anchor bolts, (4) a scenario with anchorage concrete cracking, and (5) a perfect correlation of the above three degradation scenarios. This paper will present the methodology for the time-dependent fragility calculation and discuss the insights drawn from this study. To achieve a better understanding of the effects of aging on the performance of structures and passive components (SPCs) in nuclear power plants (NPPs), the Korea Atomic Energy Research Institute (KAERI) and Brookhaven National Laboratory (BNL) are collaborating to develop seismic fragility analysis methods that consider age-related degradation of SPCs. The rate of age-related degradation of SPCs was not found to be significantly large, but increasing as the plants get older. The slow but increasing rate of degradation of SPCs can potentially affect the safety of the older plants and become an important factor in decision making in the current trend of extending the operating license period of the plants (e.g., in the U.S. from 40 years to 60 years, and even potentially to 80 years). In this paper, a condensate storage tank (CST) was analyzed to estimate its seismic fragility capacities under various postulated degradation scenarios. This paper will present the methodology for the time-dependent fragility calculation and discuss the insights drawn from this study.
- Research Organization:
- Brookhaven National Lab. (BNL), Upton, NY (United States)
- Sponsoring Organization:
- KOREA ATOMIC ENERGY RESEARCH INSTITUTE
- DOE Contract Number:
- DE-AC02-98CH10886
- OSTI ID:
- 1017406
- Report Number(s):
- BNL-95202-2011-CP; R&D Project: 87014; TRN: US1103244
- Resource Relation:
- Conference: 19th International Conference on Nuclear Engineering (ICONE19); Chiba, Japan; 20110516 through 20110519
- Country of Publication:
- United States
- Language:
- English
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Seismic Fragility Analysis of a Condensate Storage Tank with Age-Related Degradations
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Related Subjects
36 MATERIALS SCIENCE
42 ENGINEERING
AGING
BNL
CAPACITY
CONCRETES
CONDENSATES
CONTAINMENT
DECISION MAKING
DESIGN
EARTHQUAKES
FASTENERS
KAERI
LIFE SPAN
NUCLEAR ENGINEERING
NUCLEAR POWER PLANTS
OPERATING LICENSES
PERFORMANCE
SAFETY
STAINLESS STEELS
STORAGE
TANKS
seismic fragility
age-related degradation
nuclear power plants