Analysis of Spray Tests in a Multi-Compartment Geometry Using the GOTHIC Code

Abstract

The effect of spray on the gas mixing in the multi-compartment geometry of the PANDA facility is investigated using the GOTHIC code. Two tests using two connected vessels are analysed, where water was injected from a full-cone spray nozzle placed in the upper part of one vessel. In the vessel where the spray was located, the upper region was filled with a helium-rich mixture. The remaining volume of the vessel and the second vessel were filled with a denser fluid. The difference between the two tests was the presence of air: one test was performed with steam and helium only, whereas in the second test air was also present in the gas mixture in both vessels. These experiments have been analysed with the advanced containment code GOTHIC. The results showed that the code tends to overpredict the depressurisation rate when the standard correlations for natural convection heat transfer between fluid and structures are used. With respect to mixing, generally good results were obtained. The timing of the stratification break-up above the nozzle injection, however, could not be reproduced. Finally, the large effect of the initial mixture composition on the evolution of the gas distribution in the connected vessel was well predicted.