Study on improvement of gas entrainment evaluation method

Ito, Kei; Ohshima, Hiroyuki; Xu, Y.*; Imai, Yasutomo*

Japan Atomic Energy Agency has conducted the FaCT project to study a conceptional design of a large-scale sodium-cooled fast reactor in which the coolant in the vessel has relatively higher velocity than conventional designs and may causes cover gas entrainment (GE) in an upper plenum region. The authors has been studied a evaluation method of GE in fast reactors and the 1st proposal (prototype) of "Design Guideline for Gas Entrainment Prevention Using CFD Method" was published in 2006. In this study, the prototype evaluation method was improved by introducing the surface tension and turbulent effects. The improved GE evaluation method was validated by analyzing the gas core lengths observed in simple experiments. Results showed that the analytical gas core lengths calculated by the improved GE evaluation method were shorter in comparison to the prototype GE evaluation method, and gave better agreement with the experimental data.