Leading CFD models for innovative nuclear applications at CRS4

In the last 15 years, CRS4 has developed a consolidated experience in CFD simulations in the field of innovative nuclear system. The complexity of the applications has progressively increased during these years and we present three of the most recent ones. The first application regards the construction of a CFD model of the entire primary coolant loop of MYRRHA, the future Belgian multi-purpose Lead-Bismuth Eutectic (LBE) cooled nuclear reactor, built in the framework of the FP7 SEARCH project. The second application regards the control rod insertion dynamics in the MYRRHA framework, for use in the FP7 MAXSIMA project. The third application concerns the conception of liquid Lead spallation target for the European Spallation Source (ESS), developed during the FP7 THINS project. The model of the MYRRHA primary coolant loop combines a free-surface flow and a thermal flow, driven by hydraulic pumps. Heat is provided by the reacting nuclear core and removed by heat exchangers and thermal irradiation from the containment vessel. The conjugate heat exchange with the main internal structures is also taken into account. Being a pool reactor, the coolant is in contact with the cover gas. The contact is established at different levels in relation to the pressure drop between the different fluid volumes, essentially between the hot and the cold plenum. The model of the MYRRHA control rod requires the use of moving meshes in the numerical CFD simulation and a good control of the topological deformations that could lead to important numerical errors. Mesh morphing and re-meshing techniques are employed in the transient analysis of the buoyancy driven control rod system. Full-scale CFD simulations of the control rod displacement in its guide tube are presented. The buoyancy acts as the driving force and the control rod is stopped by a dedicated spring. The model has thus a two-way dynamical coupling. The model for the ESS requires the analysis of a free surface beam target subject to a pulsed beam deposition. The slow transients of the free surface evolution and the fast transients due to shock wave propagation inside the liquid target are simulated by means of a dedicated code based on the Smoothed Particle Hydrodynamic method implemented on a GPU architecture in order to dramatically increase the performance.

@InProceedings{PMM14,
  author       = {Profir, M. and Moreau, V. and Massidda, L.},
  title        = {Leading CFD models for innovative nuclear applications at CRS4},
  booktitle    = {THINS 2014 International Workshop on Thermal Hydraulics of Innovative Nuclear Systems Modena, Italy, January 20-22},
  month        = {january},
  year         = {2014},
  organization = {UNIMORE-Università degli Studi di Modena e Reggio Emilia},
  keywords     = {CFD, nuclear system, spallation target},
  url          = {https://publications.crs4.it/pubdocs/2014/PMM14},
}