The simultaneous occurrence of different load conditions such as gravity loads, lateral and vertical loads due to seismic event in various combinations should be considered to generate most critical design conditions on Nuclear Power Plant (NPP) components. The aim of this paper is to evaluate the behaviour and the structural response in form of response spectra of the reactor building internal structures, under site specific seismic loading, and to determine whether these ones satisfy current international safety regulations. A preliminary conceptual analysis and design of a nuclear building with different foundation embedding depths for the most critical conditions were discussed with reference to solutions considered for a Near Term generation Nuclear Power Plant. The seismic input motion was considered as a free field response spectrum with 0.2 g PGA, while the Soil-Structure Interaction (SSI) effects were taken into account through appropriate features. To achieve the purpose of this study, the foundations can be seen as a stable base for the superstructure able to transfer safely all loads from ground to the internals. The general approach was consistent with up-to-date design conditions for evaluation and upgrade of NPP facilities. The project’s major steps and objectives may be summarized as follows: study of available data for preliminary design and as built conditions, creation of 3-D detailed finite element models, determination of dynamic characteristics, verification of capability of structure to resist relevant design load combinations, determination of possible feature and components mostly affected by the assumed seismic loads. The results of the performed analyses, the possible effects of SSI and the response of internal components (e.g. Nuclear Building, Vessel-SGs etc.) seem to confirm the possibility to achieve an upgrading of the geometry and the performances of the proposed solutions for the considered NPP.
Influence of different foundation depths on the seismic response of a next generation nuclear reactor
LO FRANO, ROSA;FORASASSI, GIUSEPPE
2008-01-01
Abstract
The simultaneous occurrence of different load conditions such as gravity loads, lateral and vertical loads due to seismic event in various combinations should be considered to generate most critical design conditions on Nuclear Power Plant (NPP) components. The aim of this paper is to evaluate the behaviour and the structural response in form of response spectra of the reactor building internal structures, under site specific seismic loading, and to determine whether these ones satisfy current international safety regulations. A preliminary conceptual analysis and design of a nuclear building with different foundation embedding depths for the most critical conditions were discussed with reference to solutions considered for a Near Term generation Nuclear Power Plant. The seismic input motion was considered as a free field response spectrum with 0.2 g PGA, while the Soil-Structure Interaction (SSI) effects were taken into account through appropriate features. To achieve the purpose of this study, the foundations can be seen as a stable base for the superstructure able to transfer safely all loads from ground to the internals. The general approach was consistent with up-to-date design conditions for evaluation and upgrade of NPP facilities. The project’s major steps and objectives may be summarized as follows: study of available data for preliminary design and as built conditions, creation of 3-D detailed finite element models, determination of dynamic characteristics, verification of capability of structure to resist relevant design load combinations, determination of possible feature and components mostly affected by the assumed seismic loads. The results of the performed analyses, the possible effects of SSI and the response of internal components (e.g. Nuclear Building, Vessel-SGs etc.) seem to confirm the possibility to achieve an upgrading of the geometry and the performances of the proposed solutions for the considered NPP.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
