Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf

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Modeling of flashing-induced instabilities in the start-up phase of natural-circulation BWRs using the code FLOCAL

Manera, A.; Rohde, U.; Prasser, H.-M.; van der Hagen, T. H. J. J.


This paper reports on the modeling and simulation of flashing-induced instabilities in natural circulation systems, with special emphasis on natural circulation Boiling Water Reactors (BWRs). For the modeling the 4-equation two-phase model FLOCAL (Rohde, 1986), developed at the Forschungszentrum Rossendorf (FZR, Germany), has been used. The model allows for the liquid and vapor to be in thermal non-equilibrium and, via drift-flux models, to have different velocities.
The phenomenology of the instability has been studied and the dominating physical effects have been determined. The results of the simulations have been compared qualitatively and quantitatively with experiments (Manera and van der Hagen, 2002) that have been carried out within the framework of a European project (NACUSP) on the CIRCUS facility. The facility, built at the Delft University of Technology in The Netherlands, is a water/steam 1:1 height-scaled loop of a typical natural-circulation-cooled BWR.

Keywords: Flashing; instabilities; experimental; numerical

  • Nuclear Engineering and Design 235(2005)14, 1517-1535