Abstract
It can be seen that the studies on fuel assembly mixing performance in the reports are all focused on the influence factors of thermal parameters, and few on the structural parameters. In order to systematically investigate the influence of radial power distribution of rod bundles on the mixing characteristics of fuel assembly, the experimental study was carried out by a 14 ft 5 × 5 full-length rod bundle fuel assembly with both left-right symmetry and center-symmetric arrangement of cold and hot rod bundles. CFD numerical simulation method was used to calculate the same condition. The results show that the radial power ratio of the rod bundles has little effect on the mixing coefficient kT of the fuel assembly when the rod bundle is centrally symmetrical. When the rod bundle is left-right symmetrical, the temperature matrix of the sub-channel section presents an angular symmetry phenomenon near 45°. The experimental results and CFD simulation both show that the configuration of the mixing vanes forms a macroscopic diagonal circulation of the fluid in the sub-channel. FLLICA-IIIF subchannel software could not accurately simulate the diagonal circulation phenomenon of the fluid in the subchannel.
