With the title "Development of interfacial velocity correlation for benchmarking porous media based three-dimensional code for steam generator", Dr.HIBIKI's

paper was published in the Journal of Nuclear Science and Technology was selected Preeminent Monograph Award of the Atomic Energy Society of Japan.

A steam generator is one of the essential components in Pressurized Water Reactors. One of its critical design issues is to prevent heat transfer tube damage caused by corrosion and flow-induced vibration. When designing a U-tube bundle of steam generators, a thermal hydraulic simulation code is used to predict velocity and density distribution along tubes, especially porous-media-based code, from the viewpoint of computational cost. The code first calculates a control-volume-averaged velocity. A mass conservation equation converts it to the area-averaged mixture volumetric flux at the smallest gap between two tubes. Then, the area-averaged mixture volumetric flux is converted to the local interfacial velocity at the center of the sub-channel using an interfacial velocity correlation. Comparison between measured and calculated interfacial velocities ensures the validity of the simulation code. The validation process for the code requires an interfacial velocity correlation. This study shows the newly developed interfacial velocity correlation applicable to two-phase flow in a tube bundle with a square array. The prediction uncertainty of the correlation is +6.7% (bias) + 24.2% (random error). The correlation based on an analytical equation suggests that the correlation has good scalability to apply to a wide range of flow and geometrical parameters.