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Torikawa, Tomoaki*; Odaira, Naoya*; Ito, Daisuke*; Ito, Kei*; Saito, Yasushi*; Matsushita, Kentaro; Ezure, Toshiki; Tanaka, Masaaki
no journal, ,
On free surface of a sodium cooled fast reactor, gas entrainment can be caused by free surface vortices, which may result in disturbance in core power. It is important to develop an evaluation model to predict accurately entrained gas flow rate. In this study, the effect of pressure gradient in vortex axis direction on the gas entrainment flow rate is investigated in a simple gas experimental apparatus, in which upper and lower tanks are connected by a suction pipe. As a result, it was observed that there are two flow regime: swirling annular flow regime shows the tendency that only the gas entrainment flow rate increases with almost constant pressure gradient, then, when liquid plug is induced by the development of free surface disturbance, the gas entrainment flow rate increases as the pressure gradient increases. In addition, it was confirmed that the transformation of those two flow regimes is advanced by higher liquid level in the upper tank.
Ito, Kei*; Odaira, Naoya*; Ito, Daisuke*; Saito, Yasushi*; Matsushita, Kentaro; Ezure, Toshiki; Tanaka, Masaaki
no journal, ,
In a sodium-cooled fast reactor, the inflow of entrained gas by a free surface vortex in the reactor vessel into the reactor core may cause reactivity disturbance. Therefore, a method to evaluate the gas entrainment (GE) volume flow rate is required in the design of fast reactors. In this study, as part of the investigation of the mechanism determining the GE volume flow rate, the numerical analysis targeting the free surface vortex in an experimental system in which the upper and lower cylindrical containers are connected by piping was performed, and the GE volume flow rate under various pressure conditions was evaluated. As the result, it was confirmed that the change in GE volume flow rate when the pressure difference between the upper and lower containers was changed was consistent between the experimental and analysis results, and that the GE volume flow rate could be evaluated by numerical analysis.