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Journal Articles

Experiments of coolant accumulation in SG U tube and analytical model development

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.

Oral presentation

Study on model development for liquid accumulation in steam generator U-Tube, 3; Flow observation

Yamaji, Tatsuya*; Koizumi, Yasuo; Yamazaki, Kohei*; Otake, Hiroyasu*; Hasegawa, Koji*; Hasebe, Yoshiaki*; Onuki, Akira*; Nishi, Hiroaki*

no journal, , 

Experiments of counter-current two-phase flow of upward steam flow and condensing downward film flow in a pipe were performed. The experiments were intended to examine water accumulation in steam generator U-tubes during intermediate and small break loss-of-coolant accidents of a pressurized water reactor. The inner diameter and the length of a test flow channel used in the experiments were 18 mm and 4 m, respectively. A transparent polycarbonate tube was used as the test tube since flow observation was mainly intended. When the vapor velocity was low, condensate flowed down on the inner wall of the test tube and flowed out from the bottom inlet of the test tube. As the vapor velocity was increased, slug flow came out at the intermediate elevation of the test tube and the condensate flowed up and flowed out from the top outlet of the test tube. At the lower elevation, the condensate flowed down and flowed out from the bottom outlet. This state have not been observed in the water-air experiments. The unique state for the water-vapor condensing counter-current two-phase flow was found out.

Oral presentation

Study on model development for liquid accumulation in steam generator U-Tube, 4; Data analysis on differential pressure

Yamazaki, Kohei*; Otake, Hiroyasu*; Hasegawa, Koji*; Hasebe, Yoshiaki*; Yamaji, Tatsuya*; Koizumi, Yasuo; Onuki, Akira*; Nishi, Hiroaki*

no journal, , 

Experiments of counter-current two-phase flow of upward steam flow and condensing downward film flow in a pipe were performed. The experiments were intended to examine water accumulation in steam generator U-tubes during intermediate and small break loss-of-coolant accidents of a pressurized water reactor. The inner diameter and the length of a test flow channel used in the experiments were 18 mm and 4 m, respectively. In the present experiments, the test tube was changed from the polycarbonate tube that had large heat transfer resistance to a bras tube that had low heat transfer resistance so as to cover wide range for the condensing film flow rate. Since the vapor velocity was large in present experiments, the condensate film flowed upward and flowed out from the top outlet of the test tube. A flow state in the test tube was upward annular two-phase flow. Pressure drop between the inlet ad the outlet of the test tube was well expressed with the Lockhart-Martinelli correlation for the two-phase flow pressure drop. The experimental results suggested to promise the possibility for data accumulation in the future.

Oral presentation

Study on model development for liquid accumulation in steam generator U-tube, 5; Experimental results on single and multi-channels

Yamazaki, Kohei*; Otake, Hiroyasu*; Hasegawa, Koji*; Yamaji, Tatsuya*; Koizumi, Yasuo; Onuki, Akira*; Kanamori, Daisuke*

no journal, , 

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. Two kind experiments were performed; single channel experiments and parallel four channel experiments. The inner diameter and the length of the test flow channels were 18 mm and 4 m, respectively. The experiments were performed by using steam and water at 0.1 MPa. It was confirmed that 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 water accumulation in the test pipe in the four channel experiments was smaller than in the single channel experiments. In the four channel experiments, the condensing rate of steam decreased as steam flowed upward although the steam condensing rate was uniform along the channel in the single channel experiments. This difference in the experimental condition between the two kind experiments might result in smaller water accumulation in the four channel experiments than in the single channel experiments.

Oral presentation

Study on coolant accumulation in sg U tube upflow side during natural circulation reflux cooling condition of small break loss-of-coolant accidents of pressurized water reactors

Koizumi, Yasuo; Yamaji, Tatsuya*; Yamazaki, Kohei*; Otake, Hiroyasu*; Hasegawa, Koji*; Onuki, Akira*; Kanamori, Daisuke*

no journal, , 

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.

5 (Records 1-5 displayed on this page)
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