Abstract: An on-line sipping air delivery system that propels bubbles across the entire surface of the fuel assembly. A pump delivers liquid through an aspirator located near the bottom of the fuel handling mast. Liquid flow through a venturi in the aspirator causes a drop in pressure inside the aspirator and pulls air into the aspirator through an ambient air line that extends above the surface of the liquid. The air is mixed with liquid as it flows through the aspirator and the mixture is injected under the fuel assembly through nozzles positioned at the bottom of the assembly. Suction nozzles above the liquid level at the top of the fuel assembly are used in a conventional manner to capture and deliver the released air and gases to appropriate testing equipment.

Abstract: A debris resistant fuel rod sleeve that is received over the lower end of a fuel rod. The sleeve extends above the top of the lowermost spacer grid. Openings are spaced apart around the circumference of the sleeve to correspond to the location of hard stops in the spacer grid. The hard stops are received in the openings and retain the sleeves in position during operation and during reconstitution or recaging if necessary. The outboard side of the peripheral sleeves may be provided with top and bottom lead-in features to prevent hang-ups.

Abstract: A nuclear fuel assembly debris filter. Each fuel rod has a ring attached to the lower end cap. The rings are shaped and sized to define a space between the lower end cap and ring such that the space serves to trap, or filter, debris before it reaches the elevation of the fuel cladding. The rings may be circular, elliptical, or any suitable shape that provides the desired filtration effect.

Abstract: A tool for use with an integral reusable locking arrangement between the guide tubes and upper end fitting in a nuclear fuel assembly. A positioner on the tool locates the tool on the upper end fitting grillage and aligns a wrench on the tool with projections on a spring collar used in the locking arrangement. The wrench on the lower end of the tool has slots that engage with the reusable locking arrangement on the guide tube upon application of downward pressure on the tool driver. Rotation of the driver causes corresponding rotation of the spring collar on the reusable locking arrangement for locking or unlocking of the upper end fitting in place relative to the guide tubes. Axial and rotational motion of the driver is limited by interaction between a set screw on the positioner and slots in the driver. Upward motion of the driver disengages the wrench from the spring collar for removal of the tool.

Abstract: A combined lower end fitting and debris filter for a nuclear fuel assembly is provided that does not require multiple parts, welding, brazing, mechanical fasteners, drilling or EDM operations to form the coolant flow holes. The lower end fitting and debris filter are cast as a single work piece that includes the coolant flow holes in the casting process. This is accomplished by casting the sections of the filtration surface having flow holes in a thickness that allows for the small coolant flow holes to be formed as part of the casting process.

Abstract: A device for calibrating a criticality detector for a nuclear fuel manufacturing plant having a radiation source comprises a radiation protective holder for containing the radiation source. The holder is aligned with the criticality detector along an axis; and a measuring rod having a plurality of calibrations is connected to the criticality detector and positioned near the holder parallel with the axis. A nylon guide is connected to the holder and movably connected to the measuring rod for moving the holder and the radiation source along the axis for detection purposes while providing a calibration measurement.

Abstract: An upper end fitting for a nuclear fuel assembly that eliminates the problem of free standing fuel assemblies leaning out of range of the lead in provided when installing the reactor upper internals structure. The outer dimensions of each upper end fitting in the fuel assembly are larger than their respective spacer grids and lower end fittings such that the nominal gap between upper end fittings is approximately 0.025 inch.

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: 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.

Abstract: An integral reusable locking arrangement between the guide tube and upper end fitting of a reconstitutable fuel assembly that eliminates all loose fastener components at the reactor site. A retainer sleeve is fabricated as an addition to or part of the upper end sleeve of the guide tube assembly. The retainer sleeve is formed from a cylindrical tube that has a plurality of flexible tabs spaced around the circumference of the tube at the lower end and substantially at the mid section of the tube. The lower tabs serve to center the guide tube in a hole in the upper end fitting or top nozzle. The mid section tabs extend beyond the shoulder of a counterbore in the hole in the upper end fitting or top nozzle and serve to retain the guide tube and upper end fitting in the installed position. A sleeve or collet may be inserted into the counterbore to force the tabs inward and unlock the retainer and guide tube from the upper end fitting.

Abstract: A nuclear fuel assembly lower end fitting. Two plates each having a network of diagonal and lateral ribs in conjunction with hubs for the guide thimble hole pattern are provided. The pitch between ribs corresponds to one-half of the fuel rod pitch. This allows for the fuel rods to be supported by every other rib. One plate is rotated horizontally ninety degrees relative to the other plate so that the lateral ribs of the plates are at right angles. A screen formed from approximately 0.03 inch diameter wire with 0.100 inch pitch is provided with guide tube bosses. The plates and screen are rigidly attached to each other to form a debris filtering lower end fitting.

Abstract: An integral, reusable locking arrangement between the guide tube assembly and upper end fitting of a reconstitutable fuel assembly that eliminates all loose fastener components at the reactor site. A retainer sleeve is fabricated to cooperate with the upper end sleeve of the guide tube assembly. Slots adjacent to the upper end of the sleeve receive rigid tabs on the upper end sleeve to hold the retainer sleeve and upper end sleeve together. The retainer sleeve is formed from a cylindrical tube that has a plurality of flexible curved tabs spaced around the circumference of the tube substantially at the mid section of the tube. Optional lower tabs serve to center the guide tube assembly in the upper end fitting and provide a more rigid connection. The mid section tabs are received against the shoulders of slots provided along the walls of the hole in the upper end fitting and serve to retain the guide tube assembly and upper end fitting in the installed position.

Abstract: A mixer grid for a nuclear reactor fuel assembly has a plurality of strips arranged in interlocking rows and columns defining a plurality of cells. A stopper is fixed to each corner of each cell for both directing coolant flow, providing coolant mixing and providing a smooth contact surface for the fuel rod. The stopper is either cone-shaped or cylindrical for directing and channeling coolant flow. The stopper also has a smooth, flat chamfered surface for contacting the fuel rod and minimizing damage upon the shifting of the fuel rod. The grid is attached to the nuclear reactor fuel assembly by using guide cells comprising a plurality of support arches for welding to the nuclear reactor fuel assembly.

Abstract: A spacer grid for a nuclear fuel assembly. A plurality of metal strips are interleaved on edge to define a plurality of individual cells. Each cell is sized to receive a single nuclear fuel rod. A series of projections, grid mixing vanes, extend from one edge of each metal strip and are alternately bent to extend on opposite sides of the metal strip. The alternating projections provide four grid mixing vanes that extend into each individual cell.

Abstract: An upper end fitting for a nuclear fuel assembly. A main body portion that is square in section has a base rigidly attached thereto. A combined pedestal and holddown spring assembly received in the main body portion is formed from leaf springs attached together by a bolt and nut. The leaf springs are bolted together such that the exterior radius or convex surface of the springs face each other. The bolt and nut are sized and shaped to serve as the pedestal for the control assembly of the reactor. A spring retainer movably received in the main body portion retains the springs inside the main body portion. The retainer is also provided with a bore therethrough sized to allow the bolt/pedestal to extend therethrough.

Abstract: A grid key for interior grid cells. A rectangular main body portion is bent near the middle at approximately a 90 degree angle. Two tabs that are flush with the main body portion extend outward in opposite directions from one end and along a portion of the length of the main body portion. The opposing side of the tabs is tapered at a 45 degree angle back toward the main body portion. The main body portion has a thickened section that coincides with the tabs. The thickened section is wedged between the soft stops of an individual interior grid cell to retract the stops and allow loading of a fuel rod.

Abstract: A nuclear fuel rod consolidation structure. A storage canister has a grid structure positioned in its interior. The grid structure is provided with a plurality of hexagonally shaped individual cells in a triangular pitch array. This provides nearly a two to one consolidation ratio. The grid structure provides positive radial support to the fuel rods to maintain the triangular pitch array if the canister is not fully loaded or some of the fuel rods are removed. The positive guidance allows use of the existing rod pulling device for loading fuel rods into the structure.

Abstract: A fuel rod alignment template and method for loading fuel rods in a nuclear fuel assembly. Front and rear guide plates are provided with a plurality of holes corresponding to cells in the fuel assembly to be loaded. The guide plates are rigidly connected together by connecting rods that extend beyond the front guide plate and are sized to be received in the guide tubes of the fuel assembly. When attached to the fuel assembly with the front guide plate abutting the guide tubes the holes in the guide plates and cells in the grid assemblies of the fuel assembly are in coaxial alignment. This provides positive guidance to the fuel rods as they are inserted into the fuel assembly to prevent mis-tracking and damage to the fuel assembly.

Abstract: A grid key and method for keying exterior grid cells in a nuclear fuel assembly. The grid key has a main body portion having first and second ends and is bent at approximately a 45 degree angle near the first end. Two tabs extend outward from the first end at a right angle to the main body portion to define a T-shape. The T-shaped end is inserted into the window of the exterior grid strip such that the top of the T-shape is parallel to the longitudinal axis of the grid assembly. The main body portion is then rotated 90 degrees to position the top of the T-shaped end to be perpendicular to the longitudinal axis of the grid assembly and behind the exterior grid strip. The main body portion is then pulled away from the exterior grid strip in a vertical rotating motion, causing the top of the T-shaped end to pull the exterior grid strip away from the center of the cell defined by the grid assembly.

Abstract: A nuclear fuel assembly with a debris filter. The lower end fitting of the fuel assembly has a stamped plate attached thereto that serves as a debris filter immediately upstream of the fuel rods. The stamped plate is provided with a plurality of flow holes in a size and pattern that provides filtration of debris damaging to the fuel rods while maintaining adequate coolant flow through the fuel assembly.