„Experimental investigation of density-driven vertical exchange movements of gases in rod bundle geometries“

At the Institute for Process Engineering, Process Automation and Measuring Technology (IPM) of the Zittau / Görlitz University (HSZG), extensive research on various problems of reactor safety has been performed for more than 15 years, especially on the problem of two-phase flows.

Using an existing 16x16 PWR fuel element dummy, fluid dynamic single-effect experiments of the density-driven vertical exchange movements of gases in rod-bundle geometries are conducted. By means of these small-scale experiments, the flow conditions are investigated using optical observation methods for air, model gases emulating an atmosphere of superheated steam, as well as the connection of an external steam source. Measurement technology is tested concerning its applicability. The aim is to analyze differences in the vertical transport behavior of air, fluids and water vapor in the dummy, to allow the modeling/ simulation of these processes with suitable codes.

As a result, data about the temporal behavior of gas concentrations in the fuel assembly, local velocity vectors (2D) and vortex structures of counter-current gas flows (2D), further temperature distributions and 3D information through the use of reconstruction algorithms on 2D measurement results (if necessary in several experiments under same boundary conditions with differently positioned measurement technology) are expected.

For the development of special SFP modules for ATHLETE/COCOSYS, as part of the research project, HSZG provides assistance in the radial radiation behavior for selected bundle configurations as well as in modeling the radiation behavior in simulation codes (classic and/ or knowledge-based).