Palisades Nuclear Plant Seismic Probabilistic Risk Assessment

SC Solutions supported the Seismic Probabilistic Risk Assessment (SPRA) of the Palisades Nuclear Power Plant (NPP) by performing seismic soil-structure interaction (SSI) and fragility analyses to better understand the effects of modern site-specific seismic hazard on plant risk.  With the updated seismic hazard, SC Solutions characterized realistic seismic response and fragilities for the structures within the main power block and assessed non-vibratory seismic hazards. 

SC Solutions developed detailed 3D finite element (FE) models for each structure based on as-built drawings, plant walkdowns, and verification to original design analyses.  High-fidelity SSI modeling was essential to capture local responses, soft soil effects, accurate embedment conditions, and high-frequency seismic hazard.  The models were coupled together to account for partially shared load paths, structure-soil-structure interaction (SSSI) effects, and potential for building-to-building impact.  The combined power block SSSI model was analyzed using the SC-SASSI software platform to generate in-structure demand as input for component and structure fragility analysis.

Our SPRA experts also performed fragility evaluations for the main plant structures and other select structures, systems and components (SSCs) including buried pipes, cooling water intake conduit, roof-mounted tank and its support slab, and dome-shaped truss inside containment.  SC Solutions also characterized SSC fragilities accounting for potential soil-related failures such as slope movement of site sand dunes.

Working closely with SPRA systems and risk analysts, SC Solutions applied expertise to tailor structural and geotechnical analysis approaches to provide detail and realism appropriate for plant and SSC relative risk significance, thus maximizing the cost-benefit of the analysis performed and improving risk assessment insights for plant safety.