Abstract: A weld fixture for receiving and aligning the fuel rod contact points of a nuclear fuel bundle spacer grid. Two plates are provided with intersecting unequally spaced slots that define polygons on one side of each plate. Both plates have bores therethrough substantially at the slot intersections and in the slots adjacent the outer edges of the plates. Bores are provided through both plates in polygons that correspond to fuel assembly guide tube and instrument tube locations. These positions receive guide cell pins during use, some of which are hollow and are used to bolt the plates together over the spacer grid strips. Bores in each plate through the defined polygons receive alignment pins. Guide rods receive and align the plates through corner bores in each plate. The slots and pins in the facing plates align the critical fuel rod contact points in the spacer grid during the intersection welding process.

Abstract: Disclosed is an assembly fixture and method useful for the assembly and fabrication of metal grids such as used to support and position the fissionable fuel rods of a nuclear fuel assembly. The grid assembly fixture uses a grid assembly plate (1) and a plurality of toggle clamp assemblies (9) and clamping pads (12) attached thereto to temporarily hold the four peripheral or border grid straps (7) in proper position and alignment against the four sides of the grid assembly plate (1). A strap retention assembly (13) is then placed around the four peripheral or border grid straps (7) to hold them in proper position and alignment during the further fabrication and welding of the grid straps (7).

Abstract: A modular grid welding fixture for a spacer grid that facilitates full grid laser welding of a spacer grid in one setup. The modular design allows for partial implementation of each weld type. A base plate is used for mounting to the positioning/rotational plate of the welding system. A removable sub-plate received in the base plate is used to position the grid strips for proper location for welding. A top fixture plate is aligned with the base plate and provides for mounting of a second sub-plate if required. Side plates with spring loaded pressure pads that are hinged to the top fixture plate apply uniform pressure to the outer grid strips during processing. The base plate, top plate, side plate, and pressure pads are provided with a plurality of through holes to allow access of the laser beam for welding. Corner clips are used to insure contact of the overlapping sections of the outer grid strips for proper corner welding.