Publikationsrepositorium - Helmholtz-Zentrum Dresden-Rossendorf

The removal of aerosols, vapor as well as soluble gases by injecting the mixture into a water pool is referred to as pool scrubbing, which is known to be an effective means for mitigating the source term during severe nuclear accidents. The pool hydrodynamics and bubble dynamics has a significant effect on the retention efficiency, which is however still far from being understood due to the complexity of the process. One-dimensional system or lumped parameter codes are routinely used for the calculation of the decontamination factor, which describes the particle removal capability of a pool scrubbing process. These codes rely on a number of empirical correlations, e.g. for the determination of bubble size and shape, which are correlated with some global and geometrical parameters such as nozzle diameter, submergence and injection velocity. Because of limited data and knowledge, the validity of these correlations is largely limited. Computational Fluid Dynamics (CFD) has the advantage of resolving local flow field and phenomena and is able to provide more insights in the bubble dynamics. In the frame of IPRESCA project, HZDR is participating in the work package 3.1 “bubble dynamics -CFD”. The main activities include three types of CFD simulations, respectively using: a) two-fluid model, where both mono-disperse and poly-disperse approaches are investigated, b) VOF interface-tracking method, and c) hybrid method, which incorporates the two-fluid and VOF models in one framework. The results shown possibilities and challenges of CFD in applying to pool scrubbing, and further efforts are needed.