NAFEMS International Journal of CFD Case Studies

Volume 5, January 2006

ISSN 1462-236X

Numerical Simulation of Coolant Mixing at the ROCOM Test Facility with CFX-4 and CFX-5 based on Complex Meshes

T. Höhne
Forschungszentrum Rossendorf (FZR), Institute of Safety Research, P.O. Box 510119 D - 01314 Dresden, Germany

https://doi.org/10.59972/mg4zu1sr

Keywords: Boron Dilution, CFD, Pressurised Water Reactor and Coolant Mixing

Abstract

The work was aimed at the numerical simulation of coolant mixing in the downcomer and the lower plenum of the Rossendorf test facility ROCOM. ROCOM is a 1:5 scale Plexiglas model of a German pressurised water reactor allowing conductivity measurements by wire mesh sensors and velocity measurements by LDA technique. The CFD calculations were carried out with the CFD-codes CFX-4 and CFX-5. In the case of stationary mixing, the maximum value of the averaged mixing scalar at the core inlet was found in the sector below the inlet nozzle, where the tracer was injected. The comparison of a very detailed mesh (CFX-5) and a mesh with simplifications and additional physical models (CFX-4) showed that, in the referred case, the use of these models is allowed. For turbulent flows CFX-4 and CFX-5 were validated in accordance with the Best Practice Guidelines and can be used in the reactor safety analysis. A better description of the mixing processes inside the RPV is the basis of a more realistic safety assessment.

References

[1] U. Rohde et al.: Fluid mixing and flow distribution in the reactor circuit (FLOMIX-R), Symposium FISA-2003, Luxembourg, November 10-13, 2003, Pre-proceedings pp. 198-204

[2] Prasser, H.-M., Böttger, A., Zschau, J., A new electrode-mesh tomograph for gas liquid flows, Flow Measurement and Instrumentation 9, 111-119, 1998

[3] CFX-4.4 Flow Solver User Guide, AEA Technology, 2001

[4] CFX-5.6 User Documentation, ANSYS-CFX, 2003

[5] Bernard, J.P., Haapalehto, T., Review of Turbulence Modelling for Numerical Simulation of Nuclear Reactor Thermal-Hydraulics, Research Report, Lapeenranta University of Technology, 1996

[6] ERCOFTAC Best Practice Guidelines, see http://imhefwww.epfl.ch/lmf/ERCOFTAC/

[7] F. Menter, CFD Best Practice Guidelines for CFD Code Validation for Reactor Safety Applications, ECORA FIKS-CT-2001-00154, 2002

[8] H.-M. Prasser, G. Grunwald, T. Höhne, S. Kliem, U. Rohde, F.-P. Weiss, Coolant mixing in a Pressurized Water Reactor: Deboration Transients, Steam-Line Breaks, and Emergency Core Cooling Injection, Nuclear Technology 143 (1), p.37, 2003.

[9] Ulrych G., Weber E., Neuere Ergebnisse zur Kühlmittelströmung in Druckwasserreaktoren, Atomkernenergie-Kerntechnik 42 4, 217-223, 1983.

Cite this paper

T. Höhne, Numerical Simulation of Coolant Mixing at the ROCOM Test Facility with CFX-4 and CFX-5 based on Complex Meshes, NAFEMS International Journal of CFD Case Studies, Volume 5, 2006, Pages 31-40, https://doi.org/10.59972/mg4zu1sr