Seismic Isolation of Nuclear Power Plants using Sliding Bearings

Keywords: Sliding isolation bearings, nuclear power plants, temperature dependence of friction, seismic hazard definitions, seismic risk calculations

Abstract: This report presents a study on the seismic isolation of nuclear power plants (NPPs), with a focus on single concave sliding bearings. The key goals of the study were to 1) characterize the coefficient of friction at the sliding surface, 2) determine the influence of the definition of the coefficient of friction and alternate representations of seismic hazard on the response of isolated NPPs, and 3) quantify the seismic vulnerability of isolated NPPs. Consideration of heating effects may substantially influence the response of an isolated NPP. The uniform hazard response spectrum should be used to define seismic hazard for analysis of isolated NPPs with explicit consideration of the difference in amplitude of the orthogonal horizontal components of ground shaking. A hard stop must be provided to ensure that failure of the isolation system is not a key contributor to the seismic core damage frequency. Seismic risk can be reduced by designing and testing isolators for displacements greater than those expected in beyond design basis shaking.