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discovered 02_2012

discovered 02.12 COLLABORATIONS WWW.Hzdr.DE neither to the measuring technology implemented nor to the experimental set-up. Experiments are conducted within the closed pressure tank with pressure equalization, whereby it is not required to design components that are pressure- resistant or thick-walled. In this way, the experimental set-up can be equipped with thin metal walls and even optical glass windows. While the high operating pressure is compensated through the tank itself, good thermal insulation needs to be ensured during the experiment. This is imperative, on the one hand, to protect the expensive measuring technology in the pressure tank and to minimize heat loss in the experiment, on the other hand, as this would skew the results like, for example, an additional cooling of the water mixture. For this reason, a special mineral fibrous insulating material is used for thermal insulation, which also displays excellent isolation properties under high pressure. European goals The goal of such elaborate experiments at the Helmholtz– Zentrum Dresden-Rossendorf is to improve CFD codes with the help of high-resolution data from the experiment. These will be further developed in the European projects NURESIM, NURISP and upcoming NURESAFE. The series of experiments that was inter-coordinated by the project partners covered more than 90 experiments incorporating different operating parameters in each experiment, i.e. pressure, flow level inside the main coolant pipe as well as mass flow and temperature of the emergency water. These variations are imperative not only to fulfill the requirements of the most important thermo- hydraulic characteristic numbers that can be used to scale up individual effects to plant dimension, but also to cover a wide range of parameters for current and future CFD simulations. Last but not least, comparable experiments using air-water and steam-water combinations are able to assess the effects of steam condensation that is lacking in a pure air-water system, for example. The data from these elaborate experiments already serve as comparative data to be used in the CFD calculations by the project partners. In addition, project partners within the large-scale European projects NURESIM and NURISP performed conducted comparative calculations to compare this complex thermo-hydraulic scenario with three different CFD codes (among which commercial ones). Preliminary results are already showing that further efforts must be invested in the future development of these codes – a field of research and development to which scientists at the Institute of Fluid Dynamics at the HZDR have dedicated themselves. Contact _Institute of Fluid Dynamics at HZDR AREVA Endowed Chair for Imaging Techniques in Energy and Process Engineering at the TU Dresden Prof. Uwe Hampel _Institute of Fluid Dynamics at HZDR Matthias Beyer EMERGENCY COOLING: The thermal imaging camera shows the cold leg pipe wall in a steam-water experiment as seen from below (top half of picture) and a side view of the same pipe (bottom half of picture). Temperature distribution on the cold leg pipe wall and the downcomer simulator’s surface based on results from CFD calculations.