Finite element modeling of the AP1000 nuclear island for seismic analyses at generic soil and rock sites

The AP1000 is a standard design developed by Westinghouse and its partners for an advanced nuclear power plant utilizing passive safety features. The design has been certified by the US Nuclear Regulatory Commission based on their review of seismic analyses at hard rock sites. The plant has five principal building structures: the nuclear island, the turbine building, the annex building, the diesel generator building and the radwaste building. The nuclear island consists of the containment building (the steel containment vessel and the containment internal structures), the shield building and the auxiliary building. These structures are founded on a common basemat and are collectively known as the nuclear island. This paper describes shell and stick finite element models used in fixed base dynamic analyses for the hard rock design certification using the general purpose finite element program ANSYS. It describes a coarser shell model developed for use in soil structure interaction (SSI) analyses. This model is developed in both ANSYS and the soil structure interaction (SSI) program SASSI. Results of the three types of models from ANSYS analyses are compared for a hard rock site. Results are also compared between the ANSYS and SASSI analyses for the same model.