Kraftwerk Union Aktiengesellschaft

Siemens Aktiengesellschaft

Alexander Steinke

Franz-Josef Bokers

Peter Suchy

Josef Steven

Diethelm Knodler

Gustav Fromel

Hans Kropfl

Gunter Bruch

Friedrich-Wilhelm Aisch

Hans Peter Fuchs

A spacer for a fuel assembly of a nuclear reactor includes an elongated spring which is held in a mesh in such a way that there is structural freedom with respect to a selection of a shape of the spring and that little spring material is required. Two lateral rims at a top end of the spring are bent around a center of a fuel element out of the mesh in such a way that they protrude through an assembly opening in the web into an adjacent mesh. The two rims approximately form-lockingly encompass an edge of the assembly opening through the use of a profiled section. A lower end of the spring is also correspondingly held on the web through the use of profiled sections on its two rims, which are bent outward. Two springs protruding into adjacent meshes can then also be fastened in the same assembly opening.

Spacer with specially fastened springs for fuel assemblies of nuclear reactors

In a fuel assembly, rods are disposed in meshes of a grid. Crossing points of the grid are distributed in a checker-board-like manner, partly in an upstream crossing plane and partly in a downstream crossing plane. Webs of the grid run in zigzag form between the two planes. As a result, flow resistance which is produced by the webs and/or by mixing vanes disposed thereon and by flow turbulences is shifted into different axial planes and is considerably reduced.

Fuel assembly with a grid structure between the rods

A gridlike spacer for fuel assemblies having rods in a bundle, includes polygonal grid meshes having ribs intersecting at corners and extending transversely to the rod bundle between the rods of the rod bundle. The ribs have lateral surfaces facing the rods penetrating the meshes. Springs each protrude diagonally into at least one corner of a respective one of at least a majority of the grid meshes. Each of the springs has a middle part for laterally supporting a given rod penetrating the respective mesh. The middle part is a cylinder segment curved convexly about an axis of curvature at right angles to the rod bundle. Each of the springs has two spring ends adjoining one another in the direction of the rod bundle. The middle part changes over at the spring ends with a convex curvature into two legs being approximately parallel to the rod bundle. The legs are supported at least on the lateral surface of one of the ribs facing toward the given rod.

Spacer for fuel assemblies

A nuclear reactor fuel assembly includes mutually parallel fuel rods and guide tubes for control rods. Two lattice-like spacers have mesh openings formed therein. One of the fuel rods or one of the guide tubes is guided and secured in each of the mesh openings. An additional lattice is secured at least to one of the guide tubes between the two spacers as seen in the longitudinal direction of the fuel rods and the guide tubes. The additional lattice has mesh openings formed therein defining sides of the mesh openings and a smooth and flat surface of the additional lattice in the mesh openings. Turbulence-promoting vanes protrude beyond the sides of the mesh openings formed in the additional lattice. One of the fuel rods is guided with play or one of the guide tubes is guided through each of the mesh openings formed in the additional lattice. Brackets grip the additional lattice between at least one of the fuel rods or the guide tubes at the outside of the fuel assembly.

Nuclear reactor fuel assembly

Nuclear reactor fuel assembly having a grid-shaped spacer with square grid meshes, wherein mutually parallel rods are arranged, respectively, in a grid mesh, the spacer having flat outer straps extending transversely to the rods and an intermediate strip extending parallel to the rods between two of the respective outer straps, the intermediate strip being inclined relative to the two outer straps, including a rejection rise formed at the outside of the intermediate strip and extending in direction of a diagonal of a grid mesh located at a corner between the two outer straps, the rejection rise being disposed transversely to the two outer straps and being inclined downwardly towards two respective ends of the intermediate strip in longitudinal direction of the rods.

A nuclear reactor fuel assembly having a grid-shaped spacer for retaining fuel rods, the spacer includes four flat, sheet metal outer straps disposed on edge at right angles to the fuel rods defining corners of the spacer, inner sheet metal straps disposed within the outer sheet metal straps, the inner straps include two given inner straps each being transverse to one of two respective given outer straps at a corner of the spacer dividing the spacer into meshes for fuel rods including a corner mesh at a corner of the spacer and two other meshes laterally adjacent the corner mesh, a contact spring for a fuel rod disposed in the corner mesh, the contact spring having two end parts each being locked in a respective recess formed in one of the given inner straps locking the contact spring to one of the given outer straps, the recesses starting from an end edge of the one given inner strap parallel to the fuel rods, two extended arms in the corner mesh each being integral with a respective one of the end parts and each being parallel to one of the given outer straps, and other contact springs for retaining the fuel rod in the corner mesh, each of the other contact springs having an end part being integral with a respective one of the extended arms and disposed on a respective one of the given outer straps in the corner mesh.

Spacer for centering fuel rods of fuel assemblies in water-cooled nuclear reactors, including a grid of sheet metal webs formed of a zirconium alloy and being disposed on edge, rigid bumps formed from at least some of the webs for contacting a fuel rod, at least some of the webs having relatively wide cutouts and relatively narrow lateral slots formed therein, and resilient contact elements formed of chrome nickel steel and having a head part, a base part, a resilient band connecting the head and base parts together into one piece and a bent-out point formed on the resilient band for contacting a fuel rod, the head and base parts of the contact element being insertable into the cutouts and movable into a locked position in the lateral slots formed in the webs.

Spacer for fuel assemblies of water-cooled nuclear reactors

A nuclear reactor fuel assembly with two support plates and a holding rod connecting the two support plates rigidly with mutual spacing, the holding rod having a longitudinal axis passing through both support plates, and being held at one end in a lead-through in one of the two support plates, includes, in the lead-through, an elongated holding body for the holding rod rotatable about the longitudinal axis thereof, and displaceable in direction of the longitudinal axis thereof coaxially with the lead-through; the holding body being rigidly connectible by a rotation relative to the holding rod about the longitudinal axis thereof to an end of the holding rod and tightenable against a holding shoulder in the one support plate and detachable from the holding rod; and a spring element braced against the support plate and pressing the holding body elastically against the holding shoulder.

Spacer for fuel rods assembled into a fuel assembly for nuclear reactors formed of a grid structure of sheetmetal webs passing edgewise perpendicularly through one another including resilient and rigid contact elements fastened to the sheetmetal webs, each of the fuel rods being supportable by two diagonally opposing three-point contact systems, each of the systems being formed of one of the resilient contact elements and two of the rigid contact elements, the one resilient contact element being centrally disposed, as viewed in axial direction, and the two rigid contact elements being oppositely disposed and being ring-shaped.

Spacer for nuclear reactor fuel assemblies

Spring element for holding down and bracing a fuel assembly against a hold-down plate upwardly limiting the reactor core of a nuclear reactor, includes a spring-loaded rod-shaped member separately formed independently of the fuel assembly and being slidable axially and form-lockingly into the fuel assembly.

Spring element for holding down nuclear reactor fuel assembly

A nuclear power reactor has an active zone in which a plurality of fuel elements containing a large number of fuel rods are held between two grid plates. A tension device is disclosed which is provided for each fuel element and holds the same between the grid plates. The tension device includes a resilient pressure arrangement disposed between one of the grid plates and the end portion of the fuel element facing the one grid plate for holding the fuel element against the other one of the grid plates.

Resilient tension device in nuclear reactors

For use in forming the core of a pressurized-water reactor, a fuel assembly supporting structure for holding a bundle of interspaced fuel rods, is formed by interspaced end pieces having holes in which the end portions of control rod guide tubes are inserted, fuel rod spacer grids being positioned by these guide tubes between the end pieces. The end pieces are fastened to the end portions of the guide tubes, to integrate the supporting structure, and in the case of at least one of the end pieces, this is done by means which releases that end piece from the guide tubes when the end pieces receive an abnormal thrust force directed towards each other and which would otherwise place the guide tubes under a compressive stress that would cause them to buckle. The spacer grids normally hold the fuel rods interspaced by distances determined by nuclear physics, and buckling of the control rod guide tubes can distort the fuel rod spacer grids with consequent dearrangement of the fuel rod interspacing. A sudden loss of pressure in a pressurized-water reactor pressure vessel, can result in the pressurized coolant in the vessel, discharging from the vessel at such high velocity as to result in the abnormal thrust force on the end pieces of each fuel assembly, which could cause buckling of the control rod guide tubes when the end pieces are fixed to them in the normal rigid and unyielding manner.

Growing community of inventors

Ebermannstadt, Germany

Alexander Steinke