Simulation of Soil Structure Interaction Supporting Seismic Shake Table Tests of Full-Scale Dry Storage of Spent Nuclear Fuel

July 15, 2022

Sandia National Laboratories (SNL), under the Spent Fuel Waste Disposition (SFWD) program, is planning to conduct a series of earthquake shake table tests to determine the strains and accelerations on fuel assembly hardware and cladding during earthquakes of different magnitudes to better quantify the potential damage an earthquake could inflict on spent nuclear fuel rods. The shake table experiments will include one dry cask sitting on a concrete pad poured over the platen of the shake table. The effects of the underlaying soil, as well as the neighboring casks as in an actual spent fuel storage installation, are numerically simulated through Soil-Structure Interaction (SSI) analyses and incorporated in the input motion to the shake table.

A set of SSI Analyses are performed with two main objectives: (1) generate (SSI) input motions for the shake table, and (2) simulate the seismic cask behavior to inform the experimental program. A phased implementation is used for seismic simulations. Equivalent linear SSI analysis is performed in Phase 1. The response output SSI motions are used as input motion for a Phase 2 model. Nonlinear structural analysis using the input motions obtained from Phase 1 SSI analyses are performed in Phase 2. Significant deviations from the structural response at the concrete pad with respect to the input motion invalidates the equivalent linear input motion. Valid equivalent linear SSI motions are used as shake table input motions. Critical cases, those for which the input motions display significant deviation thus invaliding the case for equivalent linear analysis, are evaluated in Phase 3. It is envisioned to perform nonlinear SSI analysis in Phase 3 for the selected critical cases identified in Phase 2. The output motions from the nonlinear SSI analyses performed in Phase 3 are to be used as shake table input motions.

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26th International Conference on Structural Mechanics in Reactor Technology: Transactions, SMiRT-26, Berlin/Potsdam, Germany

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Derrick Watkins