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Yamaji, Tatsuya*; Koizumi, Yasuo; Yamazaki, Kohei*; Otake, Hiroyasu*; Hasegawa, Koji*; Onuki, Akira*; Kanamori, Daisuke*
Konsoryu Shimpojiumu 2015 Koen Rombunshu (USB Flash Drive), 2 Pages, 2015/08
Experiments of condensing counter-current two-phase flow in a vertical pipe were performed. This study was intended to examine water accumulation in the up-flow side of steam generator U-tubes of a PWR during the reflux cooling stage of a small break LOCA. It has been apprehended that the water accumulation may result in temporary core liquid level depression. The inner diameter and the length of a test flow channel used in the experiments were 18 mm and 4 m, respectively. The experiments were performed by using steam and water at 0.1 MPa. Two kinds of experiments were conducted; visualization experiments by using a transparent test section and quantitative water accumulation evaluation experiments by using a brass test section. Even if water on the inner surface of the test pipe could not flow downward at the lower portion of the test pipe, a part of water became to flow downward at the upper portion of the test pipe since steam velocity decreased because of condensation. Thus, two-phase mixture level was formed in the upper portion of the test pipe, which resulted in the water accumulation in the pipe. The model to predict the water accumulation was proposed. It predicted the water accumulation reasonably well.
Uesawa, Shinichiro; Nagatake, Taku; Jiao, L.; Liu, W.; Takase, Kazuyuki; Koizumi, Yasuo; Yoshida, Hiroyuki
no journal, ,
no abstracts in English
Ito, Kei; Koizumi, Yasuo*; Ohshima, Hiroyuki; Kawamura, Takumi*
no journal, ,
The authors are developing a high-precision CFD code with an enhanced interface tracking method to simulate the gas entrainment (GE) phenomena in sodium-cooled fast reactors (SFRs). The GE in SFRs is characterized by an elongated interfacial dent (gas core) along the vortex core and the bubble pinch-off at the tip of the gas core. The authors have developed physics-basis algorithms which model accurately the interfacial shape (gradient and curvature) and the mechanical balance condition at an interface. In this paper, a simple experiment of the GE is simulated to validate the developed code. The simulation result of the bubble pinch-off and the entrained flow rate shows good agreement with the experimental data, that is, the developed simulation code can be applicable to the evaluation of the GE in SFRs.