Isolation systems influence in the seismic loading propagation analysis applied to an innovative near term reactor

Frano, Rosa Lo; Forasassi, G.

doi:10.1016/j.nucengdes.2010.07.023

Cited by 28 publications

(14 citation statements)

References 9 publications

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“…The information relating to its design and layout and materials is gathered in Carelli et al 2004 [21]: a more realistic investigation of the plant safety margin is therefore possible minimizing uncertainties. Specifically, in the present study we focus on the investigation of the containment building that is the last defence in depth barrier against release of radioactivity to the environment (plant description is also provided by Forni 2009 and Lo Frano 2010 a, b [22,23]). Figure 3 shows a general breakdown for the safety assessment of NPP components with major subsets: as illustrated in the flow chart, the structural performance is dependent on the risk assessment, understanding of dominant process (demand under the postulated event), and actions/effects induced on the safety relevant equipment.…”

Section: Bdbe Safety Assessment: Methodology and Analysismentioning

confidence: 99%

“…In (1), S d and S a are, respectively, the spectral displacement and the spectral acceleration. Afterwards, given the total mass of the plant, the number of isolators (N is ) based on their own properties (e.g., damping and stiffness) is calculated as [23]…”

Section: Seismic Safety Assessmentmentioning

confidence: 99%

“…Finally, the iso-elastic model used to represent isolators is also improved by taking into account the influence of the ratio between the equivalent period and superstructure period. [23]. To do that, several SI-H 500/50 specimens of 0.5 m in diameter and 0.178 m in height were tested ( Figure 5).…”

Section: Fem Modellingmentioning

confidence: 99%

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Benefits of Seismic Isolation for Nuclear Structures Subjected to Severe Earthquake

Frano

2018

Science and Technology of Nuclear Installations

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The Fukushima accident has reiterated that the seismic safety is a clear necessity in the design of nuclear power plants. To overcome the weaknesses of the plant design, appropriate measures or interventions have thus to be put in place to improve the nuclear safety. In this study, seismic isolation, widely adopted for conventional constructions, is considered as retrofit measure to provide superior performance of plant itself, even when exceptional events occur. In this paper, we numerically investigate the dynamic behaviour of a Small Modular Reactor (SMR) plant subjected to 0.6g PGA; in doing that time-history analysis has been performed assuming the reactor building with and without isolators. For that purpose, a suitable FEM model has been implemented to provide in-structure response spectra at safety relevant locations and subsystem supports. Adequate steel and concrete properties as well as isolators properties, experimentally determined, have been assumed. Results have shown the benefits of seismic isolation for NPP that can so sustain levels of loading beyond the design input and demonstrated that failure of an isolation system cannot occur before failure of the isolated structure. However, the large horizontal displacements of the structure require appropriate considerations in the layout and interfaces for interconnected systems.

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Section: Bdbe Safety Assessment: Methodology and Analysismentioning

confidence: 99%

Section: Seismic Safety Assessmentmentioning

confidence: 99%

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Benefits of Seismic Isolation for Nuclear Structures Subjected to Severe Earthquake

Frano

2018

Science and Technology of Nuclear Installations

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“…The isolators have also been employed to protect primary structures and nonstructural components for nuclear power plant (NPP). Using properly designed isolation systems and detailed three-dimensional numerical models, it is found by some researchers that seismic isolation can significantly reduce the seismic responses of NPP structures and nonstructural components [30][31][32][33][34]. To demonstrate the advantage of isolators for NPPs, other researchers adopted simple lumpedmass stick models [35][36][37].…”

Section: Introductionmentioning

confidence: 99%

Sequential Ground Motion Effects on the Behavior of a Base-Isolated RCC Building

Zheng

Pan

Bao

2017

Mathematical Problems in Engineering

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The sequential ground motion effects on the dynamic responses of reinforced concrete containment (RCC) buildings with typical isolators are studied in this paper. Although the base isolation technique is developed to guarantee the security and integrity of RCC buildings under single earthquakes, seismic behavior of base-isolated RCC buildings under sequential ground motions is deficient. Hence, an ensemble of as-recorded sequential ground motions is employed to study the effect of including aftershocks on the seismic evaluation of base-isolated RCC buildings. The results indicate that base isolation can significantly attenuate the earthquake shaking of the RCC building under not only single earthquakes but also seismic sequences. It is also found that the adverse aftershock effect on the RCC can be reduced due to the base isolation applied to the RCC. More importantly, the study indicates that disregarding aftershocks can induce significant underestimation of the isolator displacement for base-isolated RCC buildings.

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“…Seismic isolation has been used effectively in a number of critical applications to protect important civil infrastructure [1] and seismically isolated structures have performed as expected in major earthquakes in Japan, the US, and elsewhere [2,3]. As a result, there is active interest in using seismic isolation in developing new seismically resilient NPPs and related facilities [4][5][6][7][8][9].…”

Section: Introductionmentioning

confidence: 99%

Seismic Soil-Structure Interaction Analysis of Isolated Nuclear Power Plants in Frequency Domain

Zhou

Wei

2016

Shock and Vibration

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One important aspect of applying seismic isolation to Nuclear Power Plants (NPPs) is that the complex interactions of flexible soil, flexible isolators, and stiff structures require careful investigation. In this paper, a NPP model was used to investigate the effects of SSI and the effects of changing soil and isolator properties on seismic response of an isolated NPP. The following aspects are considered in the study: horizontal excitation and vertical excitation; linear and equivalent-linear models of the isolators; scaling of the shear modulus of the soil profile model; and scaling of the horizontal equivalent stiffness of the isolators. It was found that Pseudospectral Acceleration (PSA) in the nuclear structure at the frequencies near the natural frequency of the structure increase with elevation, and the difference between the in-structure response spectral acceleration with and without SSI effects is concentrated at the frequencies near the natural frequencies of the superstructure. It is also found that the linear SSI analysis underestimates the in-structure response of the nuclear structures compared to the equivalent-linear SSI analyses, and the soil profile properties directly affect the effectiveness of the isolation system.

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Isolation systems influence in the seismic loading propagation analysis applied to an innovative near term reactor

Cited by 28 publications

References 9 publications

Benefits of Seismic Isolation for Nuclear Structures Subjected to Severe Earthquake

Benefits of Seismic Isolation for Nuclear Structures Subjected to Severe Earthquake

Sequential Ground Motion Effects on the Behavior of a Base-Isolated RCC Building

Seismic Soil-Structure Interaction Analysis of Isolated Nuclear Power Plants in Frequency Domain

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