Thermal-Hydraulic Characteristics of Sodium-Water Reaction Jet; Effect of Cover Gas Pressure on Temperature Distribution

Futagami, Satoshi  ; Kurihara, Akikazu ; Yatabe, Toshio

As a basic test for establishing the mechanism-theoretical evaluation technique of the water leak phenomenon in steam generator, free jet test(Run-FJ series) was carried out with spouting the steam in the stagnant liquid-sodium without heat transfer tubes. In the test, the temperature distribution was measured in detail, and the effect of the cover gas pressure was evaluated. As a test parameter, 2 cases of the cover gas pressure were selected(Run-FJ-1:0.5 MPa (gauge), Run-FJ-2:0.05MPa (gauge)). The water leak rate was made to be intermediate scale leak rate (0.2 kg/sec). From this test, following conclusions were obtained on sodium-water reaction jet. (1) Phase condition of the reaction jet is estimated from temperature oscillation intensity distribution. In the region where gas phase seems to become dominant, it shows the high temperature oscillation, and it agrees with the tendency in the distribution of the void output. For this reason, the heat transfer coefficient would decrease in the high oscillation area. (2) High-temperature region of Run-FJ-1 and Run-FJ-2 were narrower than Run-HT-1(heat transfer tubes existed). In comparison Run-FJ-1 with Run-FJ-2, the width of high-temperature region was similar. However, the length of high-temperature region of Run-FJ-2 is longer than Run-FJ-1 (Run-FJ-1: about 25cm, Run-FJ-2: about 50 cm). (3) Temperature distribution of the reaction jet depends on the cover gas pressure. It is because the behavior of the reaction product, hydrogen, seems to become dominant in the downstream of the reaction jet, and the behavior of the flow condition in the upstream of the reaction jet is effected by the jet stream. (4) Maximum temperature of the reaction jet is effected by the cover gas pressure (Run-FJ-1: 1048 degree, Run-FJ-2: 979 degree). It is considered that the boiling point of liquid sodium influences the maximum temperature, and that change of the gas phase by the cover gas pressure also influences the maximum temperature.