Seismic Isolation of Nuclear Power Plants using Elastomeric Bearings

Keywords: Elastomeric isolation bearings, nuclear structures, heating, cavitation, tension, extreme loading, verification and validation

Abstract: This report addresses US Nuclear Regulatory Commission-mandated issues for seismic isolation of nuclear power plants (NPPs). Advanced numerical models of low-damping rubber (LDR) and lead-rubber (LR) elastomeric bearings are developed to permit analysis of base-isolated NPPs subjected to extreme earthquake loadings. The models are verified and validated following ASME best practice, and implemented in OpenSees and ABAQUS to enable use by researchers and the design professional community. Experiments are conducted to characterize behavior of elastomeric bearing under tensile and shear loadings. Numerical issues in computing response of base-isolated NPPs are addressed. Two representations of a NPP isolated with LR bearings, a two-node macro model and a lumped-mass stick model, are subjected to design and beyond design basis earthquake shaking. Simplified and advanced representations of LR bearing behavior are considered. The results allow a reader to judge which representation of an isolated NPP (macro model or lumped-mass stick) and which features, if any, of the advanced isolator model are needed to compute response for different intensities of earthquake shaking.