General Electric Company

Other

Eric B Johansson

Bruce Matzner

Harold B King

Robert B Elkins

Gerald M Latter

Michael V Curulla

Jaime A Zuloaga, Jr

Thomas G Dunlap

Richard A Wolters

Kevin L Ledford

Russell L Crowther

David W Danielson

David Grey Smith

Ronald B Adamson

Cedric D Williams

Donald C Bartosik

Paul W Sick

John L Harmon

Gary E Dix

Mickey O Marlowe

Anthony P Reese

Richard A Proebstle

Edward A Croteau

Edward S Walker

Donald G Muncy

Harold L Nelson

Carl R Mefford

Dale H Klahn

Louis C Bulger

Jerry T Spell

The ferrule spacer includes a ferrule having an elongated slot with a pair of tabs projecting laterally into the slot. An elongated spring has opposite ends bearing against the interior wall of the ferrule and flats overlying the tabs along the outside of the ferrule. The mid-span portion of the spring projects in a central aperture between the ferrule tabs for biased bearing engagement against the fuel rod. The fuel rod is maintained against oppositely disposed stops formed on the ferrule. The spring is inserted and removed from the inside of the ferrule.

Nuclear fuel assembly spacer and spring

A spacer includes a plurality of ferrules welded to one another to form a structural integral matrix for locating fuel rods in a fuel bundle. Each ferrule has a pair of stops along one side of the ferrule and a central opening along its opposite side. An elongated flat spring having openings straddling a central cross-piece is disposed along an outer edge of the ferrule with the spring openings receiving band portions of the ferrule above and below the opening through the ferrule. The intermediate cross-piece bears against an adjoining ferrule whereby the end portions of the spring bear against the rod in the one ferrule, biasing it against the opposite stops. Thus ferrule/spring construction reduces the quantity of material of the ferrule, thereby improving performance without sacrificing structural integrity.

Reduced height spacer for nuclear fuel rods

In a fuel bundle assembly (B) for a nuclear reactor wherein a plurality of fuel rods (R) and at least one water rod (W) extend between an upper tie plate and a lower tie plate, an improvement includes a fixed connection between the water rod (W) and the lower tie plate (L), the fixed connection including a threaded lower end plug of the water rod and a threaded hole in a boss formed in the lower tie plate adapted to receive the threaded lower end plug, the threaded lower end plug (50) formed with a diametrical slot (54) therein and the boss (56) formed with a pair of slots (60, 62) extending from opposite sides of the hole such that the diametrical slot (54) and the pair of slots (60, 62) are alignable when the threaded lower end plug (50) is threaded into the boss (56); and a key (64) insertable within the aligned slots to thereby fix the water rod against rotational movement.

Water rod attachment in a nuclear reactor fuel bundle

The lower tie plate grid includes cylindrical bosses and webs interconnecting the bosses for supporting nuclear fuel rods and defining flow channels through the grid for flowing coolant upwardly about the fuel rods. The grid includes shaped body members having flow openings, the members being disposed in each of the flow channels. In one form, the members define with the side walls of the bosses and webs a debris retention zone. In another form, sets of generally parallel, laterally spaced bars are disposed at discrete elevations in the flow channels. The bars are orthogonally related to one another whereby the effective debris catching area is defined by the openings through the crossed bars in plan, while the coolant flow area comprises essentially the space between each set of bars.

Lower tie plate debris catcher for a nuclear reactor

An improved method for assembling bundles of nuclear fuel rods which reduces damage to the fuel cladding surface as the fuel rods are passed through an array of spacers. In particular, the invention prevents or greatly reduces the severity of longitudinal scratches on the fuel rods. The method uses thin-walled metallic tubes having a wall thickness of 0.003 to 0.006 inch and a yield strength in excess of 140,000 psi. The predetermined tube thickness ensures that the tube remains elastic. The tube deflects the cell springs when inserted in the spacer cells and reduces the load exerted on the fuel rods.

Method for preventing scratches on fuel rods during fuel bundle assembly

A fuel bundle and lower tie plate assembly for a nuclear reactor includes a plurality of fuel rods supported between an upper tie plate and a lower tie plate assembly. The lower tie plate assembly includes an upper grid portion and a lower body portion, the upper grid portion having a plurality of fuel rod supporting bosses interconnected by a plurality of webs thus forming flow openings between the bosses. The body portion includes an inlet nozzle and a peripheral wall extending between the bottom nozzle and the upper grid portion to define a flow volume therein. A debris catcher is located within the flow volume and includes a pair of superposed plates, the plates each having a plurality of holes of substantially the same size, shape and pitch, but wherein the holes of one of the pair of plates are offset from the holes of the other of the pair of plates by one half the hole pitch.

Low pressure double offset plate catcher for a nuclear reactor

A spacer for use with a fuel bundle in a nuclear reactor includes a matrix of ferrules for surrounding individual fuel rods within a bundle; a band surrounding the matrix and defining a peripheral wall of the spacer, the band having an upper edge; and a plurality of laterally spaced flow tabs extending upwardly from the upper edge, each flow tab having a lower substantially vertical portion and an upper inclined portion extending away from the vertical portion. The vertical portion and the inclined portion are formed with centrally located creases which define reverse bends in the upper and lower portions of the tab.

Flow tabs for a fuel rod bundle spacer

A fixturing tool includes a sleeve having a central region with a circular axial opening and four leaf springs projecting from each of the opposite ends of the central region. The central region is cruciform in cross-section with arcuate side walls between the projections of the cruciform. Unit cells are arranged on a base having openings corresponding in location to the centers of the unit cells in their final assembly in a spacer for a nuclear fuel rod bundle. Fixturing devices are freely and loosely disposed within the unit cells and pins are partially inserted through the fixturing devices to expand the leaf springs to engage the unit cells. Once the cells with fixturing devices and partially inserted pins are centered over the base openings, the pins are advanced into the openings in the base to accurately align each unit cell relative to one another to enable final welding of adjacent cells to one another.

Apparatus and methods for fabricating spacers for a nuclear fuel rod

A unitary one-piece lower tie plate grid has a lower portion and an upper portion for supporting the fuel rods. The lower tie plate grid includes cylindrical boss portions extending upwardly from the lower grid portion and arranged in square matrices for receiving the lower end plugs of the fuel rods. Web portions extending upwardly from the lower tie plate portion interconnect the boss portions along the sides of the matrices. The lower grid portion includes a plurality of openings which open into the flow spaces defined by the convex portions of the bosses and the webs within each square matrix of the upper portion of the tie plate. Coolant flows through the openings into the flow spaces for further flow upwardly about the fuel rods. The openings are radiussed adjacent their lower ends and have divergent side walls downstream of a throat area to define a flow venturi.

Spring assemblies are employed in adjoining ferrules of a spacer in a nuclear fuel bundle to bias the fuel rods against stops and hence position the fuel rods in the spacer. The spring assemblies in one form include back-to-back spring bodies having central leaves with forward projections extending through rectilinear openings in adjacent ferrules to engage fuel rods to bias the rods against stops at the opposite sides of the ferrules. Outer pairs of leaves straddle the central leaf and project rearwardly and join the spring bodies one with the other whereby the central leaves, end portions of the springs connected to the central and outer leaves, and the outer leaves act as paired springs in series, providing a low spring constant. In another form, a single spring body has a central leaf with a projection extending through an aperture of a ferrule to bias the fuel rod. The outer leaves bear against the outer surface of the adjoining ferrule. In this latter form, pins may be used to compress the springs to facilitate insertion of the fuel rods into the ferrules.

Spring assemblies for adjoining nuclear fuel rod containing ferrules and

In a boiling water reactor fuel bundle, a three dimensional debris catching grid construction is placed within the flow volume defined by the lower tie plate assembly between the inlet nozzle and upper fuel rod supporting grid. A perforated plate is utilized having round holes as small consistent with the prevention of inadvertent closure due crudding and a hole pitch consistent with mechanical integrity requirements. The perforated plate is placed in a three dimensional construction such as a dome, cylinder, pyramid, inverted pyramid or corrugated construction spanning the flow volume of the lower tie plate assembly. As a consequence of this three dimensional grid construction, the total flow through area of the perforations in the metal plate does not introduce appreciable pressure drop in the lower tie plate assembly between the inlet nozzle and the rod supporting grid. Fluid movement at the debris restraining holes of the grid construction has a low flow velocity and a change in flow direction before passing through the holes to discourage debris from finding its way through the grid holes. Finally, it is possible to incorporate debris traps within the flow volume of the lower tie plate assembly that can cause trapping and subsequent removal of trapped debris upon fuel bundle replacement. A double corrugated plate having large holes in the lower plate and smaller holes in the upper plate is utilized to trap debris.

Lower tie plate strainers including double corrugated strainers for

A fuel bundle assembly for a nuclear reactor, wherein a plurality of fuel rods and at least one water rod extend between an upper tie plate and a lower tie plate, includes upper end plugs secured to a pair of water rods and having axial cut-out portions defined by upper and lower shoulders. A latching mechanism for securing the pair of water rods to the upper tie plate includes a latch bar mounted on an upper surface of the upper tie plate and rotatable into and out of the cut-out portions in the end plugs when the end plugs extend above the upper surface of the tie plate upon installation of the upper tie plate on the fuel bundle assembly. A locking pin is provided which prevents the latch bar from being accidentally unlocked.

Latching and lifting mechanism for a nuclear reactor fuel bundle

A unitary one-piece lower tie plate grid has a lower portion and an upper portion for supporting the fuel rods. The lower tie plate grid includes cylindrical boss portions extending upwardly from the lower grid portion and arranged in square matrices for receiving the lower end plugs of the fuel rods. Web portions extending upwardly from the lower tie plate portion interconnect the boss portions along the sides of the matrices. The lower grid portion includes a plurality of openings which open into the flow spaces defined by the convex portions of the bosses and the webs within each square matrix of the upper portion of the tie plate. Coolant flows through the openings into the flow spaces for further flow upwardly about the fuel rods. The openings are radiussed adjacent their lower ends and have tapered divergent walls opening into the flow spaces. In another form, the openings have a step intermediate the upper and lower surfaces of the lower grid portion to define a minimum cross-sectional flow area.

Leaf-type springs are inserted into slots in an upper tie plate of a nuclear fuel assembly and bear against interior surfaces of the fuel channel to center the upper tie plate within the fuel channel. More robust similarly configured leaf springs are secured in slots in the upper tie plate and are cantilevered for bearing engagement through slots in the fuel assembly channel against the reactor top guide to bias the fuel assemblies toward the control rod. To mount each spring to the upper tie plate, the base of each leaf spring includes a central beam and a pair of outermost beams spaced from the central beam, all beams lying in a common plane. Laterally outwardly directed tabs are provided on the lower ends of the outer beams. Stops are provided intermediate the ends of the outer beams. By inserting the unstressed, unloaded base of the springs into the slots, the outer beams are displaced inwardly into a stressed condition. Once the tabs extend past the lower surface of the tie plate, the beams return to an unloaded, unstressed condition with the tabs and stops locking the springs to the tie plate. The distal ends of the springs bear against the channel or top guide, as applicable, to locate the upper tie plate within the channel and bias the fuel assembly and channel toward the control rod, respectively.

Spring retention of upper tie plate and fuel bundle channel in a nuclear

A unitary one-piece lower tie plate grid has a lower portion and an upper portion for supporting the fuel rods. The lower tie plate grid includes cylindrical boss portions arranged in square matrices for receiving the lower end plugs of the fuel rods. Web portions interconnect the boss portions along the sides of the matrices. The lower grid portion includes a plurality of openings which open into the flow spaces defined by the convex portions of the bosses and the webs within each square matrix of the upper portion of the tie plate. Coolant flows through the lower flow openings into the flow spaces for further flow upwardly about the fuel rods. The openings are defined by the convex lower portions of the bosses and webs, as well as projections which extend laterally inwardly from the convex surfaces of the lower boss portions toward a central region in the middle of the square matrix. The projections are cylindrical and terminate short of one another to define a generally cloverleaf-shaped flow opening having multi-lobes which, in conjunction with the projections, catch debris while maintaining coolant flow into the flow spaces above the projections at minimum pressure drop.

Growing community of inventors

Wrightsville Beach, NC, United States of America

Eric B Johansson