Westinghouse Electric Corporation

Robert Duncan

David A Boatwright

John S Kerrey

Kenneth K Klapper

Ralph W Kalkbrenner

Richard M Kobuck

Richard A Miller

Wade H Widener

Denis Yeo

William E Kirby

James E Craver

Richard P Barna

An end stop is adapted for engaging the sealing plug positioned in the end of a nuclear fuel rod and so as to permit the evacuation of the fuel rod to facilitate girth welding of the plug onto the rod, and to permit pressurization of the fuel rod and an enclosing welding chamber to facilitate the seal welding closure of the axial opening in the end stop. The end stop includes an axial passage extending therethrough having a welding electrode coaxially positioned therein to facilitate the seal welding closure of the fuel rod sealing plug. An air channel extends between the axial passage and an outlet on the surface of the end stop. A one-way valve is positioned in the air channel for permitting the free passage of a gas from the axial passage to the outlet into the welding chamber while precluding passage of a gas in the reverse direction.

End stop for welding sealing plugs of nuclear fuel rods

A nuclear fuel assembly grid comprising an improved outer grid strap wherein abutting outer grid strap segments are joined at a point of intersection with an inner grid strap. The normally preformed weld where the inner strap fork tines extend through the outer grid strap thereby fixedly bonds the outer grid strap segments together.

Nuclear fuel grid outer strap

A novel weld chamber and process for using such weld chamber are disclosed. A flow of shielding gas through the weld chamber is regulated to provide a constant pressure in the weld chamber while the shielding gas flow sweeps away metal vapors.

Pressurized weld chamber

A welding apparatus has a welding chamber with an access opening allowing passage of a cladding tube end fitted with an end plug to a welding position therein. A rotatable end plug stop assembly disposed in the chamber and axially aligned with the access opening is adapted to engage the end plug when inserted in the welding chamber. An end of a electrode of a girth welding assembly disposed in the welding chamber adjacent to the rotatable end plug and tube end and in generally orthogonal relation thereto is operable to form a girth weld circumferentially joining the end plug and cladding tube end. An end seal welding assembly mounted to the end plug stop assembly and having an electrode with an end disposed adjacent to and in axial alignment with an axial bore of the end plug is operable to form an end seal weld therein. The end seal welding assembly also defines a path for flow of a fill gas along the electrode and both into the welding chamber and the end plug axial bore before formation of the end seal weld therein. The end plug stop assembly includes an end stop which receives an end seal welding electrode and flow of fill gas along the electrode, and an end plug-engaging insert adapted to fit in the end stop and engage the end plug leading end portion.

Fuel rod end plug welding apparatus and method

A workpiece handling assembly for supporting and positioning each side of a multi sided workpiece in the path of a welding laser beam. The workpiece handling assembly includes a frame indexably movable in a plane perpendicular to the direction of the welding laser beam. The frame has a central opening therein through which the welding laser beam may be projected. A carrier secures the workpiece so that it is positioned within the frame in a plane in parallel overlying relationship with the aperture. The frame is rotatably supported about a transverse axis parallel to the aperture, the carrier is rotatably supported on the frame about a central axis which is orothogonal to the transverse axis. The workpiece supported in the workpiece handling assembly of the invention is movable through an angle of 360.degree. about the transverse axis and through an angle of 360.degree. about the central axis, so that all sides of the workpiece may be positioned in the path of the laser beam without removing the workpiece from the assembly.

Workpiece handling assembly

An improved retention strap for maintaining a fuel assembly grid in an assembled condition during manufacture in a grid assembly fixture includes four members extendible along the respective outer grid straps, between the corners and about the periphery of the grid. Each member has a pair of end posts and a cross member extending between and connected with the end posts. The end posts of the members are disposed adjacent the respective corners of the grid when the grid is in the assembled condition. Pairs of brackets interconnect respective ones of the end posts of the members, whereas pairs of releasable connectors fasten respective others of the end posts of the members so as to form diagonally opposite pairs of substantially rigidly squared first fixed and second openable corners. Also, the retention strap includes a pair of clamps disposed at each of the fixed and openable corners formed by the end posts. The clamps are engagable with a selected one of the end portions of the outer grid straps forming the respective grid corner disposed adjacent one of the squared corners of the retention strap. The outer grid strap end portion selected is the one having a terminal edge defining the inner part of the lap joint at the grid corner. The clamps have inner hook-shaped elements which engage on the selected end portion to pull outwardly thereon and thereby pull outwardly on the other end portion of the pair thereof forming the grid corner which secures the end portions against the respective one of the squared corners of the retention strap and thereby prevents distortion of the grid corner during welding of each respective lap joint at a corner of the grid. Each clamp also has a second adjustable element adapted to bear against the retention strap member and exert an outwardly-directed pulling force on the outer grid strap end portion via the first element thereon.

Retention strap in a grid assembly fixture

A welding fixture for a nuclear fuel assembly grid having rigid top and bottom members and having apparatus for releasably securing them together. The bottom and top members each have an egg-crate configuration of interleaved fixture straps. Top notches on the bottom fixture straps' top edges are placed to engage the grid straps' bottom edges when the grid straps are aligned for welding. Likewise, bottom notches on the top fixture straps' bottom edges are placed to engage the grid straps' top edges when the grid straps are aligned for welding.

Welding fixture for nuclear reactor fuel assembly grid

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.

Grid and sleeves welding fixture and method

A grid of a fuel assembly structure for a nuclear reactor comprises two sets of uniformly spaced straps perpendicular to each other for receiving and supporting cylindrical sleeves. The straps forming cells which receive the sleeves have notches at their edges, and the sleeves are joined to the straps by lap welding at the notches.

Fuel grid with sleeves welded in notched grid straps

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.

Welding plates for a fuel rod grid

A process for welding the adjacent ends of frame members peripherally surrounding the interleaved straps of a fuel assembly grid which includes placing the assembled grid and its frame members into a fixture made to substantially the same dimensions as the outside dimensions of the grid. The side members of the frame are arranged such that a space appears at each of the four corners and a special tool placed in each of the four corner cells of the grid is designed to have an opening which corresponds to the openings formed on each corner of the fixture. After the tooling is placed in each of the four corner cells, the assembled grid and fixture is then placed in welding apparatus such that a welding tip thereof is placed in the tool located in a corner cell. Since the opening in the tool and between the plates of the fixture and at each corner are in alignment, the welding tip accordingly moves through the openings and into contact with the overlapping ends of the frame members placed on the peripheral surface of the grid. The upper welding tip is then brought into contact with the other side of the overlapping ends and a spot weld accordingly applied to the frame member overlapping ends.

Process for welding corner cells in fuel assembly grids

Process and apparatus for simultaneously pressurizing a fuel rod having a plug in one end, welding a plug in the other end and sealing a gas pressurizing orifice therein in a single operation. A weld chamber is provided which accommodates one end of a seal rod having a plug fixed in the rod end by a friction fit. A mechanism pushes the fuel rod into the weld chamber which is then pressurized to force gas through a plug orifice into the fuel rod. During subsequent rotation of the rod, an electrode in the weld chamber forms a weld puddle which bridges the end plug-fuel rod interface and the plug orifice to thereby weld the plug in the rod and seal the plug orifice in a single operation.

Process and apparatus for sealing nuclear reactor fuel

An arrangement for applying a constant load on the probe of a coordinate measurement machine to eliminate errors caused by operator hand pressure when the probe is manually moved into engagement with a part being measured. In coordinate measurement machines, a carriage movable in the Y axis direction bridges the part being measured. A probe on the carriage is movable in the X axis direction thereby permitting probe movement in any quadrant in X-Y axis directions. To eliminate measurement errors in the Y axis direction, a constant load is applied to the probe by a pair of spring motors mounted on opposite ends of the machine. These spring motors are connected by spring motor cables to the carriage. When the back cable is attached to the carriage, the applied force urges it in the +Y axis direction, and the front cable when attached, urges the probe in the -Y axis direction. To apply a constant load on the probe in the X axis direction, spring motors are mounted on opposite ends of the carriage. Cables from these motors are selectively connected to the probe housing to respectively urge the probe in the +X or - X axis directions. By connecting appropriate spring motor cables to the carriage and probe housing, constant loads are applied to the probe which urges it in the X-Y axis directions in any one of four quadrants.

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Fork, SC, United States of America

Robert Duncan