General Electric Company

Global Nuclear Fuel - Americas, LLC

Gerald M Latter

Eric B Johansson

Bruce Matzner

Robert B Elkins

Harold B King

Russell Patrick Higgins

Thomas G Dunlap

Carlton Wayne Clark

Edward A Croteau

Steven Bruce Shelton

Mark J Colby

Richard Carl Longren

Michael R Stepp

Brandon P Smith

David Grey Smith

John L Harmon

Anthony P Reese

David W White

Richard A Proebstle

Michael V Curulla

Christian D Frederickson

Richard G Patterson

Thomas G Evans

Debris filters fit in fuel assembly lower tie plates and filter fluids passing therethrough. Filters use a series of adjacent plates with aligned peaks and valleys to create several channels. The plates have small excisions in diamond, triangle, or other debris-catching shapes, such as near a lower portion of the filter where fluid enters the filter. Excisions may alternate around each channel, such as four alternating cut-outs in 90-degree intervals about a channel circumference. Excisions may be sized to entrap smaller debris common in reactor coolant flow and liable for fretting damage to fuel cladding. Multiple vertical stages can be used in filters, with different channels for each stage. Ligaments may hold each stage to the next, potentially with a gap between stages for intermixing. Plates, peaks, valleys, ligaments, and excisions may all be formed in a single stamping operation to eliminate excess or overlapping pieces or extensions.

Methods of forming debris filters for nuclear fuel assemblies

Debris filters for nuclear fuel assembly and method of using the same

A debris trap catches debris falling through a fuel bundle orifice in a nuclear reactor. The debris trap includes a shaft and a debris capture tray attached to an end of the shaft. The debris capture tray includes a tray cavity sized larger than the fuel bundle orifice.

Debris trap

Debris Trap

A fuel bundle assembly for a nuclear reactor includes a modified channel and a handle unit that improves pressure drop performance. With the modified channel, one approach is to vary the outside dimension of the fuel channel along the length of the channel, but maintain a constant channel wall thickness. Another approach is to maintain the external dimensions of the fuel channel and vary the wall thickness along the length of the channel. The handle unit is formed including a handle member and a separate rod support member releasably engageable with the handle member. The handle member includes channels for receiving latch pin assemblies, coolant rods and a spacer assembly. The rod support member includes a plurality of fuel rod support chambers providing lateral support for the fuel rods of the fuel assembly. The rod support member also includes a main chamber that is sized to receive a portion of the handle member in a friction fit. In addition to providing improved pressure drop performance, the arrangement eliminates the need to realign the fuel rods in an upper tie plate or an upper spacer when access to the fuel rods is necessary. In addition, the handle unit serves to prevent failed end plugs from escaping the fuel bundle.

Handle unit for a fuel assembly in a nuclear reactor and fuel assembly

A fuel bundle assembly for a nuclear reactor includes a modified channel that improves pressure drop performance and a handle assembly that includes structure for preventing a broken end plug from escaping the fuel bundle. In modifying the channel, one approach is to vary the outside dimension of the fuel channel along the length of the channel, but maintain a constant channel wall thickness. Another approach is to maintain the external dimensions of the fuel channel and vary the wall thickness along the length of the channel. The handle assembly replaces the conventional upper tie plate and is provided with structure for preventing debris such as a broken fuel rod end plug from escaping the fuel bundle. The structure preferably includes a plurality of gridwork cross members forming a substantially square grid including gridwork windows that are sized smaller than the fuel rod end plugs.

Handle assembly and channel for a nuclear reactor fuel bundle assembly

The spacer comprises a plurality of strips interleaved with one another to form an eggcrate-type pattern defining essentially rectilinear cells for each fuel rod. Each strip includes a central body portion with cantilevered loop spring-like projections extending to opposite sides, with spring contact portions projecting inwardly. Stops are provided along each of the central body regions of the strips intermediate the loop springs that project to the opposite side of the strip. Adjoining walls have loop spring portions for biasing the rod into engagement with opposing stops whereby each fuel rod is supported at six contact points, i.e., four spring contact points and two hard stop contacts opposite the paired spring contacts.

Multi-spring strip spacer for nuclear fuel bundles

In a nuclear reactor fuel bundle assembly having a plurality of fuel rods and a non-round water rod extending between upper and lower tie plates, and having at least one fuel rod spacer located along the non-round water rod, an improvement which includes cooperating components on the fuel rod spacer and on the water rod for permitting movement of the spacer along the water rod to a desired axial location and for thereafter preventing further axial movement of the spacer in at least one of two opposite axial directions, the cooperating components including at least one spring on one of the spacer and the water rod.

Spacer capture mechansim for non-round water rods

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.

Lower tie plate debris catcher for a nuclear reactor

A spacer array is disclosed in which alternating cells are disposed at differing elevations. In a preferred octagonal spacer cell array, alternate fuel rods within the rows and columns of the fuel bundle matrix are surrounded by octagonal spacer cells at a first elevation. Likewise, and in the same preferred octagonal spacer array, the remaining alternate fuel rods within the rows and columns of the fuel bundle matrix are surrounded by octagonal spacer cells at a second elevation. The octagonal spacer cells of the spacer array at one level adjoin the octagonal spacer cells of the spacer array at an adjacent level. Specifically, each octagonal spacer cell has the top and/or the bottom of as many as four of its eight sides disposed for joinding with one side of as many as four octagonal cells in an adjacent cell layer. Each cell has approximately 0.6 of an inch height, or one-half the 1.2 inch height of the prior art. Physically each cell would have approximately half the height of the prior art cell type spacers. There results a spacer cell array which distributes half of the pressure drop at a first elevation, and the remaining half of the pressure at a second elevation for a projected spacer area of one-half that area of the prior art. Further, and because the two cell arrays making up the spacer are disposed at differing elevations--immediately above and below each other--the produced flow resistance at one level of the spacer cells does not have horizontally immediately adjacent cells. Thus, the cells in one layer do not co-act with adjacent flow frictions to the same extent as the co-action would occur if all flow frictions and restrictions were at the same elevation. There results an improved and lesser pressure drop in the disclosed spacer array.

Reduced pressure drop spacer for boiling water reactor fuel bundles

An improved spacer is disclosed which contains an Inconel grid and a Zircaloy surrounding band. The Inconel grid can be fabricated from the extremely thin and highly elastic spring metal utilizing a modification of a prior art cell construction that includes paired inwardly bent vertical spring legs with cantilevered and rod encircling upper and lower arm pairs The spring legs extend at spaced apart locations between the upper and lower arm pairs and have a medial spring rod contacting portion for biasing the rods into stops on the rod encircling arm pairs. The springs at the upper and lower ends are provided with spring dimple stops to prevent over stressing of the spring during assembly or handling of the fuel bundle into which the spacer is incorporated. The rod encircling arm pairs have an offset from center where the two arms meet at their distal ends to complete encirclement of the rods. This offset from center enables the cells to be fastened in cell pairs at their respective embracing arms. The cell pairs can in turn be manipulated as a unit to define the necessary types of spacer grids required for any particular grid construction. A preferred grid construction for a ten by ten fuel rod matrix is disclosed including a grid filling all rod lattice positions for the bottom of a fuel bundle, a grid enabling the placement of a water rod of varying diameter, and finally a grid defining missing lattice positions for overlying partial length rods and permitting upward venting of steam with minimum pressure drop. An all Zircaloy band is disclosed for surrounding containment of the Inconel grid. The band consists of two or four segments Apertures are provided in the band at the corners, and portions of the corner Inconel cells project into these apertures, keying the Inconel grid to the Zircaloy band. The band is welded into continuous encircling relation. There results a spacer with an Inconel grid and surrounding Zircaloy band having minimum pressure drop and minimum neutron absorption useful with a high density fuel rod matrix required in modern fuel bundle design.

Composite spacer with inconel grid and zircaloy band

An improved spacer is disclosed which contains an Inconel grid and a Zircaloy surrounding band. The Inconel grid can be fabricated from the extremely thin and highly elastic spring metal utilizing a modification of a prior art cell construction that includes paired inwardly bent vertical spring legs with cantilevered and rod encircling upper and lower arm pairs. The spring legs extend at spaced apart locations between the upper and lower arm pairs and have a medial spring rod contacting portion for biasing the rods into stops on the rod encircling arm pairs. The springs at the upper and lower ends are provided with spring dimple stops to prevent over stressing of the spring during assembly or handling of the fuel bundle into which the spacer is incorporated. The rod encircling arm pairs have an offset from center where the two arms meet at their distal ends to complete encirclement of the rods. This offset from center enables the cells to be fastened in cell pairs at their respective embracing arms. The cell pairs can in turn be manipulated as a unit to define the necessary types of spacer grids required for any particular grid construction. A preferred grid construction for a ten by ten fuel rod matrix is disclosed including a grid filling all rod lattice positions for the bottom of a fuel bundle, a grid enabling the placement of a water rod of varying diameter, and finally a grid defining missing lattice positions for overlying partial length rods and permitting upward venting of steam with minimum pressure drop. An all Zircaloy band is disclosed for surrounding containment of the Inconel grid. The band consists of two or four segments. Apertures are provided in the band at the corners, and portions of the corner Inconel cells project into these apertures, keying the Inconel grid to the Zircaloy band. The band is welded into continuous encircling relation. There results a spacer with an Inconel grid and surrounding Zircaloy band having minimum pressure drop and minimum neutron absorption useful with a high density fuel rod matrix required in modern fuel bundle design.

Composite spacer with Inconel grid and Zircaloy band

A spring-and-spacer assembly for maintaining fuel rods upright in a fuel assembly of a nuclear reactor core is provided. The spring is in the form of a continuous loop with first and second legs having mid-leg rod-contact regions. Bend regions are positioned on each side of each contact region extending toward the interior of the loop spring. In most positions, the spring is used to load two adjacent fuel rods. In configurations in which there is an unpaired fuel rod, a plate having a tab for contacting the spring is provided. The spring provides the desired force, such as about 2.5 pounds per fuel rod, in a small rod-to-rod spacing of less than about 0.14 inches.

Growing community of inventors

Wilmington, NC, United States of America

Gerald M Latter