Experimental study on gas entrainment due to non-stationary vortex in a sodium cooled fast reactor; Comparison of onset conditions between sodium and water

Kimura, Nobuyuki; Ezure, Toshiki ; Miyakoshi, Hiroyuki; Kamide, Hideki ; Fukuda, Takeshi*

In an innovative sodium cooled fast reactor, a compact reactor vessel (R/V) with increased sodium flow velocity was designed to reduce the construction cost. One of the thermal hydraulic problems in this design is gas entrainment at the free surface in the R/V. Sodium experiments were carried out to clarify the onset criteria of the gas entrainment due to a free surface vortex. Water experiments using a test section in which geometry is the same as that in the sodium tests were also performed. The gas entrainment in water slightly tended to take place in comparison with that in sodium under low velocity conditions.