In advanced nuclear fuel design, the outer strap of a spacer grid plays an important role on fuel assembly mechanical and thermal-hydraulic performance, e.g., precluding the risk of hang-up and improvement on the mixi...In advanced nuclear fuel design, the outer strap of a spacer grid plays an important role on fuel assembly mechanical and thermal-hydraulic performance, e.g., precluding the risk of hang-up and improvement on the mixing of the coolant. The communication of the outer strap affects the hydraulic force exerted by the spacer grid of the fuel assembly which could induce fuel assembly bow. In present study, in order to understand the influencing factors of hydraulic force exerted by the spacer grid, outer straps with various flow opening design features, different location and size are investigated by a commercially CFD （computational fluid dynamics） code, ANSYS CFX 12.1. Three dimensional rod bundles including the outer strap without and with different openings are modelled for simulation. The analysis results show that the openings on the spacer grid outer strap can reduce the lateral hydraulic loadings perpendicular to the centerline of the fuel rods exerted by the spacer grids obviously because of the pressures inside and outside the spacer grids being balanced. Besides, influences of the opening design features on the hydraulic force, resistance characteristics and lateral flow factor are investigated in details.展开更多
文摘In advanced nuclear fuel design, the outer strap of a spacer grid plays an important role on fuel assembly mechanical and thermal-hydraulic performance, e.g., precluding the risk of hang-up and improvement on the mixing of the coolant. The communication of the outer strap affects the hydraulic force exerted by the spacer grid of the fuel assembly which could induce fuel assembly bow. In present study, in order to understand the influencing factors of hydraulic force exerted by the spacer grid, outer straps with various flow opening design features, different location and size are investigated by a commercially CFD （computational fluid dynamics） code, ANSYS CFX 12.1. Three dimensional rod bundles including the outer strap without and with different openings are modelled for simulation. The analysis results show that the openings on the spacer grid outer strap can reduce the lateral hydraulic loadings perpendicular to the centerline of the fuel rods exerted by the spacer grids obviously because of the pressures inside and outside the spacer grids being balanced. Besides, influences of the opening design features on the hydraulic force, resistance characteristics and lateral flow factor are investigated in details.
