FP7MAXSIMA_323312_D3.8_CFD-simulation-control-rod-system-at-COMPLOT_Final

In the framework of the MAXSIMA project, we simulate the dynamics of the Control Rod (CR) system of the MYRRHA facility, as in the COMPLOT experimental facility, under development at SCK•CEN. The transient behavior of the full scale control rod in a flowing Liquid Bismuth Eutectic (LBE) environment is simulated by CFD means. The insertion must be performed in less than 1s, under the buoyancy influence, and is slowed down by means of a damper which forces the fluid through a series of discharge slots. The original geometry of the fluid path is modeled with high fidelity, while some simplifications are made for the moving component. In the first part of the work, a 3D-CAD model provided by the designer was used for the computational geometry; in the last part of the work, the geometry was constructed autonomously according to the definitive COMPLOT design. Given the complexity both of the geometrical model and of the physics, the simulation of the movement has been split in two distinct steps. The preliminary stage regards half of the movement of the absorber pins bundle. Moving mesh techniques are developed and strategies for the conservation of a good quality mesh are implemented, paying particular attention to the solution independence with respect to the re-meshing operations. Suitable boundary conditions, compatible with the displacement, are determined. The second step would have been to reproduce the second part of the CR movement in a more complex configuration, facing the limitation of the re-meshing technique. However, in the meantime, the overset mesh methodology implemented in STAR-CCM+ reached sufficient maturity, allowing the entire CR displacement to be simulated in one shot. The method is applied to reproduce the CR motion as in the COMPLOT experiment, with several preliminary simplifications and gradual increased geometrical accuracy. The displacement is imposed, according to SCK•CEN theoretical calculations; preliminary two-way coupling simulations, with the displacement inferred by Newton law from the force balance on the CR, have also been performed. The numerical methodology and the results are illustrated and discussed.

@Misc{PM15,
  author       = {Profir, M. and Moreau, V.},
  title        = {FP7MAXSIMA_323312_D3.8_CFD-simulation-control-rod-system-at-COMPLOT_Final},
  year         = {2015},
  type         = {Rapport de Contrat},
  keywords     = {nuclear safety},
  url          = {https://publications.crs4.it/pubdocs/2015/PM15},
}