Abstract: A debris filter bottom nozzle of a nuclear fuel assembly is spaced below the lowermost grid, supports the guide thimbles, and is adapted to allow flow of liquid coolant into the fuel assembly. The debris filter bottom nozzle includes an enclosure defining a coolant flow chamber therethrough, and an upper transverse nozzle structure composed of a consolidated array of elongated cylindrical sections disposed across the chamber of the enclosure in side-by-side relation to one another, extending axially in the direction of coolant flow through the chamber, rigidly connected together and to the enclosure, and having tubular cross-sectional configurations defining passages for the coolant flow through the chamber.

Abstract: An insert for providing a reduced inside diameter for a structural tube, specifically an instrumentation guide tube, of a nuclear fuel assembly. The insert has forming lobes which coact with the structural tube to plastically deform the structural tube and mechanically lock it with respect to grid straps of a grid assembly. The insert also has centering lobes to prevent it from being expanded in other than a coaxial alignment with the structural tube. An expansion tool is provided for sequentially registering with and expanding sequential forming lobes in a simplified manner whereby all of the operations necessary to assemble the structural tube in the fuel assembly can be easily and accurately performed.

Abstract: An insert for providing a reduced inside diameter for a structural tube, specifically an instrumentation guide tube, of a nuclear fuel assembly. The insert has forming lobes which coact with the structural tube to plastically deform the structural tube and mechanically lock it with respect to grid straps of a grid assembly. The insert also has centering lobes to prevent it from being expanded in other than a coaxial alignment with the structural tube. An expansion tool is provided for sequentially registering with and expanding sequential forming lobes in a simplified manner whereby all of the operations necessary to assemble the structural tube in the fuel assembly can be easily and accurately performed.

Abstract: A fuel assembly fabrication apparatus includes a stationary support fixture and a slide fixture mounted to one end portion thereof for movement therealong. Clamp structures are disposed in spaced relation longitudinally along the stationary support fixture. One clamp structure is mounted on the movable slide fixture and supports a top nozzle and an uppermost one of a plurality of grids of a fuel assembly. The remaining clamp structures are mounted on the stationary support fixture and support a bottom nozzle and the remaining grids. The clamp structures respectively support the top nozzle and uppermost grid and the bottom nozzle and remaining grids in generally parallel relationship with passageways defined in the top and bottom nozzles and sleeves connected on the grids being aligned for slidably receiving therethrough a plurality of guide thimbles and an instrumentation tube of the fuel assembly for attachment to the nozzles and grid sleeves.

Abstract: An insert for providing a reduced inside diameter for a structural tube, specifically an instrumentation guide tube, of a nuclear fuel assembly. The insert has forming lobes which coact with the structural tube to plastically deform the structural tube and mechanically lock it with respect to grid straps of a grid assembly. The insert also has centering lobes to prevent it from being expanded in other than a coaxial alignment with the structural tube. An expansion tool is provided for sequentially registering with and expanding sequential forming lobes in a simplified manner whereby all of the operations necessary to assemble the structural tube in the fuel assembly can be easily and accurately performed.

Abstract: An insert for providing a reduced inside diameter for a structural tube, specifically an instrumentation guide tube, of a nuclear fuel assembly. The insert has forming lobes which coact with the structural tube to plastically deform the structural tube and mechanically lock it with respect to grid straps of a grid assembly. The insert also has centering lobes to prevent it from being expanded in other than a coaxial alignment with the structural tube. An expansion tool is provided for sequentially registering with and expanding sequential forming lobes in a simplified manner whereby all of the operations necessary to assemble the structural tube in the fuel assembly can be easily and accurately performed.

Abstract: A grid structure of slotted straps interfitted at their slots to form cells containing fuel elements or thimbles. The straps are of nonuniform thickness having strips of substantially greater thickness than the regions between the strips. The strips of greater thickness extend parallel to the slots. The straps are joined along these strips of greater thickness. Grids of zirconium alloy resisting crushing are formed by joining intersecting straps by welds in the strips of greater thickness.

Abstract: A computer controlled apparatus is disclosed for performing a series of laser machining operations on a work piece in an environment comprised of a non-reactive gas with respect to the material of which the work piece is made. The computer controlled apparatus includes a machining chamber for receiving the work piece and means in the form of a pump for directing the non-reactive gas into the machining chamber at a controlled, selected rate. A laser beam is generated by a laser and is focused into a beam along a path to the work piece. An assembly is provided for selectively moving the machining chamber and its work piece therein through a sequence of steps, whereby the relative position between the work piece and the laser beam is changed such that a series of lasing operations and, in particular, welds may be effected on a sequence of selected sites of the work piece.

Abstract: A welding fixture for use in welding sleeves to a grid includes a plate having a pair of spaced pins with bushings for both locating the grid and positioning a sleeve, and abutment members; and a plurality of sleeve locating positioning pegs. A method of positioning a grid and sleeves for welding sleeves to the grid.

Abstract: Welding plates for laser beam welding of a fuel rod grid are provided, each welding plate having a surface with a set of equally spaced, parallel grooves and with a second set of such grooves perpendicular to the first set. Each of the welding plates is provided with openings therethrough at the points of intersection of the straps forming the grid, so as to expose those points of intersection to a laser beam for laser beam welding of the points of intersection. A vane side welding plate has the walls of the laser beam access openings placed so as to hold vanes extending from the straps in deflected position. Stand-off pins and clamping bolts are provided, the latter having heads with access openings for the laser beam. The welding plates are provided with protrusions which extend laterally thereof, the protrusions having precisely located holes with precision bushings therein.