Seismic SSI of Nuclear Power Plant Structures

Nuclear power plant structures are massive structures typically embedded at a considerable depth in a soil deposit. An important aspect in the seismic design of these structures is the evaluation of the dynamic interaction between the structure and the soil. This paper presents the results of a study conducted to evaluate seismic SSI effects for a partially embedded massive nuclear plant structure using the finite element method of analysis. The analyses were carried out using the finite element program LUSH which incorporates the use of variable modulus and variable damping in the soil. The high frequency ranges, which must be considered in the study of SSI for nuclear power plants, are also adequately accounted for in the computer program used. Several significant parameters that could affect seismic SSI are examined. Consideration was given to parameters affecting: (1)Accuracy; (2)core storage requirements; and (3)execution time.