Description of 'design guideline for gas entrainment prevention using CFD method' (Cooperative research)

Japan Atomic Energy Agency has conducted a conceptional design study of a sodium-cooled fast reactor in a frame work of the FBR feasibility study. The plant system concept for a commercial step is intended to minimize a vessel diameter to achieve an economical competitiveness. Therefore, the coolant in the vessel has relatively higher velocity than conventional designs. Because of the high velocity, gas entrainment prevention from a liquid surface in the reactor vessel becomes one of important issues for the thermal-hydraulic design. Gas entrainment may cause the core power fluctuation or heat transfer reduction. Therefore, it is necessary to clarify the avoidance of the phenomena in the design conditions with sufficient allowance. In order to establish a design method for the gas entrainment prevention, the gas entrainment from vortex dimples at the liquid surface was investigated by a working group that consists of members from Universities, Research institutes, Utilities and Manufacturers. The 1st proposal of 'Design Guideline for Gas Entrainment Prevention Using CFD Method' was established based on the knowledge gained from the working group activities. This report introduces each study in the working group to clarify the basis of the design guideline. A CD-ROM is attached as an appendix. (J.P.N.)