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Detailed and Simplified Structural Modeling and Dynamic Analysis of Nuclear Power Plant Structures

Abstract Details

2017, Master of Science, Ohio State University, Civil Engineering.
Probability risk assessment (PRA) of nuclear power plants (NPP) has been used since the mid-1970s to evaluate the associated risks or perform a risk-informed design of NPPs. Since its inception, PRA has considered both internal and external events to evaluate the risks to a NPP site. However, external event PRA has historically been recognized as having considerable safety margin until recent events have emphasized the need for a reevaluation. This research is part of a larger project with the goal of incorporating internal and external event PRA in a common platform using state-of-the-art methods. Specifically, the focus of the research in this thesis was to develop and evaluate structural models with different levels of complexity for several structures that are vital for seismic probabilistic risk assessment (SPRA) of NPPs. For SPRA, critical structures, systems, and components (SSCs) are investigated to evaluate their risk during seismic events. To evaluate the risk of critical SSCs, structural models are needed to predict their dynamic behavior. However, due to the large number of analyses required during SPRA, simple yet sufficient models are desired to increase the computational efficiency and reduce the run-time of models. As such, the focus of this research was to develop simple yet sufficiently accurate structural models for SSCs and to evaluate the uncertainty related to those models. Three critical NPP structures are investigated in this research to illustrate the capabilities and limitations of models with varying levels of complexity. The structures included a condensate storage tank (CST), auxiliary building, and containment structure. Realistic geometric and material properties for each structure are introduced, and both detailed three-dimensional (3D) and simplified two-dimensional (2D) models are created. Detailed 3D finite element (FE) models incorporated complex mechanical behavior such as fluid- iii structure interaction and slab flexibility. Simplified 2D models developed included lumped-mass stick models and lumped-mass-spring systems. Modal and time history analyses are used to evaluate and compare the dynamic behavior and response of both detailed and simplified models to seismic events, and the capabilities and limitations of simplified models are investigated. For CSTs, several available simplified lumped-mass-spring systems are developed and compared to a 3D FE model that incorporated fluid-structure interaction. Critical failure modes for CSTs are investigated using simplified and detailed models to illustrate key differences in the models. For auxiliary buildings, several different 3D building models are developed to illustrate the effects of structural irregularity and slab flexibility on simplified models. The importance of detailed 3D models is illustrated through spatial response of the 3D models compared to the singular response of simplified stick models. Finally, simplified and detailed models for a containment structure are developed. Lumped-mass stick and 3D FE models are developed to evaluate the dynamic behavior and response of each. A polar crane system is later added to one of the 3D FE models to investigate its potential failure modes. For each structure developed, the limitations and capabilities of simplified models are evaluated, and certain scenarios where simplified models are insufficient for SPRA are illustrated.
Halil Sezen (Advisor)
Abdollah Shafieezadeh (Committee Member)
Jieun Hur (Committee Member)
281 p.

Recommended Citations

Citations

  • Althoff, E. C. (2017). Detailed and Simplified Structural Modeling and Dynamic Analysis of Nuclear Power Plant Structures [Master's thesis, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1492642525831339

    APA Style (7th edition)

  • Althoff, Eric. Detailed and Simplified Structural Modeling and Dynamic Analysis of Nuclear Power Plant Structures. 2017. Ohio State University, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1492642525831339.

    MLA Style (8th edition)

  • Althoff, Eric. "Detailed and Simplified Structural Modeling and Dynamic Analysis of Nuclear Power Plant Structures." Master's thesis, Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu1492642525831339

    Chicago Manual of Style (17th edition)