Experiment on gas entrainment evaluation method from free liquid surface in a sodium-cooled fast reactor, 2; Measurement of gas core length by dynamic image processing

Endo, Kazuki*; Kobayashi, Shunsuke*; Jasmine, H.*; Sakai, Takaaki*; Matsushita, Kentaro  ; Ezure, Toshiki ; Tanaka, Masaaki  

Assuming gas entrainment (GE) to the main coolant circulation system from cover gas which is an inert gas to cover sodium coolant in a reactor vessel of the sodium cooled fast reactor, there is a concern that reactivity disturbance will occur when bubbles pass through the reactor core. Conventionally, an evaluation method based on static vortex extension theory has been employed for the GE prediction. However, it is known that the method gives rather overestimation for the GE occurrence from the unsteady traveling vortex dimple at the wide liquid surface. In order to contribute to understand the phenomena, experimental data have been accumulated by the basic water experiment. In this study, measurement was performed for the length of a gas cores that grew while moving on the free liquid surface by dynamic image processing, and the types of the GEs and the occurrence conditions were evaluated.