  Fluid-Structure Interaction (FSI) is a significant phenomenon in most nuclear
reactors, causing effects such as Flow-Induced Vibration (FIV) and
thermally-driven Core-Radial Expansion (CRE). We demonstrate that Cardinal, an
open-source coupling of NekRS and OpenMC to MOOSE, can be used for modelling
FSI by coupling the Tensor Mechanics Module from the Multiphysics Object
Oriented Simulation Environment (MOOSE) to NekRS's Arbitrary
Lagrangian-Eulerian (ALE) solver. The solid mechanics-thermal hydraulics
coupling is implemented using efficient in-memory coupling and data transfers.
We provide a preliminary demonstration of these capabilities with a 3-D FSI
benchmark for an elastic block in crossflow.
