Void fraction measurement of gas jet in sodium pool

Nishizaki, Masanori*; Tsuruoka, Hokuto*; Sugiyama, Kenichiro*; Narabayashi, Tadashi*; Ohshima, Hiroyuki

The secondary tube failure may occur due to overheating by sodium-water reaction in LMFBR steam generator. It is very important to understand the void fraction distribution in sodium pool to evaluate the overheating tube rupture. In the present study, the Ar jet of 17.3 m/s to 129.8 m/s was injected from nozzle of 3.5 mm diameter in sodium pool with 443 K and 293 K. The authors measured the void fraction without chemical reaction along the jet-center axis. As the result, the void fraction increased when the distance from the nozzle decreased. The void fraction did not change when the distance from the nozzle was blow or equal to about 1.0 mm. The void fraction in sodium was lower the that in water, it is suggested that this trend reflects the fact the surface tension of sodium is higher than that of water.