Validation of gas entrainment evaluation method in simplified hot plenum model of sodium cooled fast reactor

Ezure, Toshiki ; Akimoto, Yuta ; Matsushita, Kentaro ; Tanaka, Masaaki  

In hot plenums of sodium-cooled fast reactors, restriction of cover gas entrainment caused by vortex dimples on the free surface is an important thermal-hydraulic issue. For this reason, the authors have developed an evaluation method of gas entrainment with an evaluation tool named, StreamViewer. In this study, evaluation using StreamViewer was applied to a water experiment having a simplified hot pool geometry aiming at the validation of the evaluation method toward the application to the evaluation of a pool-type sodium cooled fast reactor. In StreamViewer, the three-dimensional distribution of pressure decrease along the vortex center line was calculated from the velocity distribution obtained by CFD analyses, and the free surface dimple depth was obtained from the hydraulic balance with the pressure distribution and the cover gas pressure. As the results, it was confirmed that the onset of gas entrainment could be predicted appropriately based on the above-mentioned calculation method.