Abstract:
The fuel rod supporting structure of spacer grid is of great importance to ensure the fuel rod at the appropriate horizontal and axial position. On the purpose of improving the neutronic economy and simplifying the manufacturing and assembling process of spacer grid, the innovative curved dimple and vaulted spring with small dimple on it were designed, which were directly punched from the zirconium strap of spacer grid. The mechanical experiments were performed to acquire the deformation-load curves of dimples and springs of single strap and in-grid cells, which could provide the load and residual deformation at 100% and 120% nominal designed deformations. The result demonstrates that the designed supporting structure has a relative stable load at the 100% nominal designed deformation, and the test method of the single strap is representative for the similar deformation-load curve between the spring and the in-grid cell.