Heat transfer experiments and numerical analysis of supercritical pressure water in seven-rod test bundle

The heat transfer experiment of supercritical pressure water in a seven-rod test bundle, which simulates SCWR rod bundle, is performed to investigate heat transfer around the fuel rods. It is confirmed from the experiment that pressure drop in the rod bundle is approximately stable with increase of bulk temperature, and that obvious difference in rod surface temperatures between the surface facing to narrowest region between rods and that facing to the center of subchannel can hardly be seen. ACE-3D is applied to the experimental analysis of seven-rod bundle heat transfer experiments. It is confirmed that ACE-3D can predict the rod surface temperature within variation in experimental results by including thermal conduction in the simulated fuel rod, that improvement in prediction accuracy of the rod surface temperature in high bulk enthalpy region remains to be solved, that ACE-3D can also predict the pressure drop by taking into account the pressure drop of grid spacers with an experimental correlation, and that difference of flow field in subchannels adjacent to between the center rod and the shroud wall increases when the bulk enthalpy is close to the pseudo critical enthalpy. (author)