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Kobayashi, Shunsuke*; Endo, Kazuki*; Jasmine, H.*; Sakai, Takaaki*; Matsushita, Kentaro; Ezure, Toshiki; Tanaka, Masaaki
Dai-27-Kai Doryoku, Enerugi Gijutsu Shimpojiumu Koen Rombunshu (Internet), 5 Pages, 2023/09
Assuming gas entrainment (GE) to the main coolant circulation system from cover gas which is an inert gas to cover sodium coolant in a reactor vessel of the sodium cooled fast reactor, there is a concern that reactivity disturbance will occur when bubbles pass through the reactor core. Conventionally, an evaluation method based on static vortex extension theory has been employed for the GE prediction. However, it is known that the method gives rather overestimation for the GE occurrence from the unsteady traveling vortex dimple at the wide liquid surface. In order to contribute to understand the phenomena, experimental data have been accumulated by the basic water experiment. In this study, the velocity distributions were measured under the conditions where GE occurs by particle image velocity (PIV) measurement in an experimental system to observe the gas cores that grow from the unsteady traveling vortex dimple.
Endo, Kazuki*; Kobayashi, Shunsuke*; Jasmine, H.*; Sakai, Takaaki*; Matsushita, Kentaro; Ezure, Toshiki; Tanaka, Masaaki
Dai-27-Kai Doryoku, Enerugi Gijutsu Shimpojiumu Koen Rombunshu (Internet), 5 Pages, 2023/09
Assuming gas entrainment (GE) to the main coolant circulation system from cover gas which is an inert gas to cover sodium coolant in a reactor vessel of the sodium cooled fast reactor, there is a concern that reactivity disturbance will occur when bubbles pass through the reactor core. Conventionally, an evaluation method based on static vortex extension theory has been employed for the GE prediction. However, it is known that the method gives rather overestimation for the GE occurrence from the unsteady traveling vortex dimple at the wide liquid surface. In order to contribute to understand the phenomena, experimental data have been accumulated by the basic water experiment. In this study, measurement was performed for the length of a gas cores that grew while moving on the free liquid surface by dynamic image processing, and the types of the GEs and the occurrence conditions were evaluated.
Endo, Kazuki*; Kobayashi, Shunsuke*; Jasmine, H.*; Takeda, Jotaro*; Sakai, Takaaki*; Matsushita, Kentaro; Ezure, Toshiki
no journal, ,
When the gas entrainment (GE) phenomenon occurs, where argon (Ar) cover gas is entrained in the coolant at the liquid surface in the reactor vessel of a sodium-cooled fast reactor, Ar bubbles may cause reactivity disturbances when they pass through the core. In this study, the number and type of GE events were measured under different outlet shapes in a rectangular open channel GE test section with a bottom slit, and the effect of change in downward flow velocity gradient on GE was analyzed by numerical analysis. The outlet shapes were two types: one with an outlet only below the slit (Outlet channel 1) and one with an outlet both above and below the slit (Outlet shape 2). As a result, it was confirmed that the number of GE events tends to increase with increasing inlet velocity in Outlet channel 1 while is significantly reduced in Outlet channel 2. The numerical analysis revealed that the decrease in the downward flow velocity gradient to the bottom suppressed GE in Outlet channel 2.
