VERIFICATION OF NUMERICAL MODELS FOR SEISMIC FLUID-STRUCTURE INTERACTION OF ADVANCED REACTOR INTERNALS

Earthquake shaking of a fluid-filled advanced reactor induces fluid-structure interaction (FSI) between the reactor vessel, the submerged internal components, and the contained fluid. Numerical models for FSI analysis will be required for seismic design and qualification of the advanced reactors in part because of the limitation of analytical solutions and physical testing. Analytical solutions cannot accommodate realistic geometry and boundary conditions of the vessel and its internal components, three-directional seismic input, and nonlinear responses of the fluid. The reactor vessels are too large to qualify on available earthquake simulators and pressure loading time series on internal components, immersed in the fluid, are too complex to reproduce with physical testing equipment such as actuators. Numerical models for FSI analysis need to be first verified and validated before being used for seismic design and qualification of a fluid-filled advanced reactor. A numerical model can be verified by comparing analysis results with those calculated using analytical solutions and validated using data from physical testing. This paper describes 1) prior analytical work on lateral frequencies of submerged internal components, 2) numerical models of an internal component submerged in a fluid confined by the wall of a tank, analyzed using the Incompressible Computational Fluid Dynamics solver in LS-DYNA, and 3) verification of the numerical models by comparing the numerical and analytical results. Validation of the verified models will be performed using data from earthquake simulator tests of a 1/10th-scale, base-supported, cylindrical tank with internal components.