Seismic Analyses of a Nuclear Power Block Considering Structure-Soil-Structure Interaction

Considering the disposed characteristics of the NPP, SSSI effect in the power block surrounding the safety related structures need to be evaluated according to SRP 3.7.2. In the APR1400 NRC DC project, which is being pursued by domestic nuclear industry, SSSI analysis is performed and applied to the structural design. The seismic response between the SSI response of each building and the emergency diesel generator building adjacent to the entire power block was directly compared and analyzed considering the SSSI effect. The analysis is performed by applying a three-dimensional finite element model. It is a result of the inevitable assumption that the structures are placed on the surface due to a problem of a large analysis time, and thus the buying effect, which is an important variable related to the SSSI effect, is not reflected. After that, additional complementary analysis was performed, but there still existed a problem of a large analysis time and limitation of the analytical model. The numerical analysis was proposed to a direct comparison of linear analysis in frequency domain and nonlinear analysis in time domain. The validity of SSSI analysis was verified through centripetal fuse experiment. We are developing user convenience for CNU-KIESSI analysis program and also installing the high-speed solver engine for the large-capacity input data, and are performing various analytical verification and validation works through the centrifuge experiment for the reduced NPP model. In this study, we examined the research trends of SSSI in domestic and overseas and found that SSSI effect should be reflected according to SRP 3.7.2. Also there are limitations on the analysis of the SSSI due to the problems of the vast analysis data and the analysis time.