JPH0376877B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an improvement in a support grid that supports a plurality of fuel rods in a nuclear reactor fuel assembly.

[Prior Art] Conventionally, this type of support grid has been provided as shown in FIGS. 7 and 8.

The support grid shown in these figures is constructed by assembling a plurality of straps 2 perpendicularly intersecting each other so as to define a large number of grid spaces 1.
A pair of convex portions 3 made of a rigid body and protruding inwardly from the lattice space 1 are provided on the wall portion of the strap 2 defining the lattice space 1.
are vertically spaced apart, and a holding part (holding member) 4 that protrudes inward of the lattice space 1 is formed on the wall facing the above so as to be elastically deformable. The fuel rods 5 inserted into the lattice space are brought into contact with the convex portions 3 by the holding portions 4, thereby elastically supporting the plurality of fuel rods 5.

[Problems to be Solved by the Invention] However, in the above-mentioned support grid, the straps are formed by plastic working to form the holding portions, so the straps may be deformed by residual stress generated by the plastic working. In such a case, there is a problem that the efficiency of assembling the support grid and the accuracy of the product deteriorate. Also, since the holding part is made of the same material as the strap, for example, if the strap is made of a material with low toughness such as Zircaloy,
There is a problem in that the holding force may be reduced due to the holding portion becoming sagging, and in such a case there is a risk that the fuel rods will shift within the support grid.

[Objective of the Invention] This invention has been made in view of the above circumstances, and it is possible to prevent the strap from deforming and the holding force of the holding part to decrease. An object of the present invention is to provide a support lattice that can increase the efficiency of assembly work and product accuracy, and can firmly support fuel rods within the support lattice.

[Means for Solving the Problems] The support grid of the present invention includes a plurality of straps that are assembled perpendicularly to each other to define a plurality of grid spaces, and a plurality of straps that extend through at least one wall of the grid spaces. a holding member extending into a plurality of lattice spaces and having both ends fixed to the walls of the lattice spaces, the holding member comprising a pair of wavy holding plates disposed facing each other; The pair of retaining plates are arranged so that the portions that are close to each other butt each other, and the portions that are separated from each other define an annular holding portion, and the axis of the holding portion is aligned with the axis of the grid space. , and the abutment portions between two adjacent holding portions are made to penetrate through the wall of the lattice space, and the abutment portions located at both ends are fixed to the wall of the lattice space.

[Embodiment] FIGS. 1 to 6 are diagrams showing an embodiment of the present invention.

FIG. 1 is a diagram showing a part of the support grid, which includes a plurality of horizontal straps 7 and vertical straps 8 so as to define a large number of grid spaces 6.
..., 9... are assembled perpendicularly to each other, and the holding members 10... are attached to the vertical straps 8..., 9...
...is placed through the wall.

As shown in Fig. 2, the horizontal strap 7 is a plate-shaped member made of Zircaloy, and has pen tip-shaped convex portions 11 extending in the longitudinal direction on the sides thereof. They are formed at regular intervals. A slit 12 is formed in the center of the convex portion 11, extending from its tip to the center of the horizontal strap 7. In addition, the horizontal strap 7
A plurality of slits 13 extending from the side edges to the center are formed at positions spaced from each convex portion 11 on the side of the convex portion 11 at a distance of one-half between the convex portions 11, 11. The dimensions of the slits 12 and 13 in the width direction are set to be slightly larger than the wall thickness of the vertical strap 8. Further, in the horizontal strap 7, long holes 14 are formed in a line in the longitudinal direction. The elongated holes 14 are provided to facilitate the flow of coolant within the fuel assembly when the fuel assembly is used in a nuclear reactor.

Further, as shown in FIG. 3, the vertical strap 8 is a plate-shaped member made of Zircaloy, and has a nib-shaped convex portion 15 projecting in the width direction on one side of the strap in the width direction. are formed at regular intervals in the longitudinal direction. Further, on the other side of the vertical strap 8, a plurality of slits 16 extending from the side edge to the center of the horizontal strap 8 are provided.
The slits 12 and 13 are spaced apart from each other at the same distance. The widthwise dimension of the slit 16 is set to be slightly larger than the thickness of the horizontal strap 7. Further, on the side of the predetermined slit 16 on the other side of the vertical strap 8, a relief part 17 is formed by cutting the side of the vertical strap 8 into a rectangular shape. Moreover, on the side of the predetermined slit 16,
A slit 18 is formed extending from the side edge to the convex portion 15 side. At the end of the slit 18 on the side of the protrusion 15,
An insertion hole 19 wider than the slit 18 is formed. These relief portions 17 and insertion holes 19
is for inserting the holding member 10 through the vertical strap 8, and the holding member 10 is fixed to the insertion hole 19. Note that the formation positions and numbers of the relief portions 17 and the insertion holes 19 are appropriately set depending on the mounting position of the vertical strap 8.

Further, the vertical strap 9 is the same as the vertical strap 8 in which relief portions 17 are formed on all sides of the slit 16.

The horizontal slit 7 and the vertical slits 8, 9 configured in this way are similar to the slits 11, 12,
16 are fitted together so as to butt each other, and in this way a plurality of vertical and horizontal straps 8..., 9..., 7... are assembled so as to cross each other perpendicularly. In the assembled state, the insertion holes 19 of the vertical strap 8 are located at both ends of two or three lattice spaces 6 lined up in the longitudinal direction of the horizontal strap 7.

The holding member 10 also includes a pair of wavy holding plates 20 and 20, as shown in FIGS.
are placed facing each other. The pair of retaining plates 20, 20 are configured such that the portions that are close to each other butt against each other, and the portions that are spaced apart from each other define an annular holding portion 21. The holding portion 21 is arranged so that its axis coincides with the axis of the lattice space 6.
Further, the abutting portion 21a between the two adjacent holding plates 20, 20 is the relief portion 1 of the vertical strap 8.
7 or the insertion hole 19, and the abutting portion 21a, which passes through the insertion hole 19, is fixed to the insertion hole 19.

In the support grid configured as above,
When the fuel rod 22 is inserted into the holding part 21 in the lattice space 6, the holding plates 20 and 2 are inserted between the insertion holes 19 and 19, as shown by the two-dot chain line in FIGS.
0 are elastically deformed in a direction that separates them from each other. Then, the abutting portion 2 of the adjacent holding portions 21, 21
1a expands until it comes into contact with the wall of the relief portion 17 of the vertical strap 8, and the fuel rod 22 is firmly held by the elastic return force of the holding plates 20, 20.

In the above-mentioned support grid, the fuel rods 22 can be held by the holding members 10 that are configured separately from the straps within the support grid, so that the straps are not deformed, and the holding members The holding force of the fuel rods 10 does not decrease, therefore, the work efficiency and product accuracy of the support grid assembly work can be improved, and the fuel rods 22 can be firmly held within the support grid. Furthermore, since the holding member 10 can be made of a material with high toughness, the holding force can be increased.

In the above embodiment, the insertion holes 19 of the vertical straps 8 are arranged at both ends of two or three lattice spaces 6 lined up in the longitudinal direction of the horizontal straps 7. It is not limited to
They may be arranged at both ends of a large number of grid spaces 6. In this case, the holding force of the holding portion 21 can be maintained by setting the widthwise dimension of the relief portion 17 small.

[Effects of the Invention] As explained above, the support lattice of the present invention includes a plurality of straps assembled orthogonally to each other to define a large number of lattice spaces, and a support lattice that penetrates at least one wall of the lattice spaces. a holding member extending into a plurality of lattice spaces and having both ends fixed to the walls of the lattice spaces, the holding member comprising a pair of wavy holding plates disposed facing each other;
The pair of retaining plates are arranged so that the portions that are close to each other butt each other, and the portions that are separated from each other define an annular holding portion, and the axis of the holding portion is aligned with the axis of the grid space. In addition, the abutting portions between two adjacent holding portions are passed through the wall of the lattice space, and the abutting portions located at both ends are fixed to the wall of the lattice space, so that the strap does not deform. This not only improves the work efficiency and product accuracy of the support grid assembly work, but also allows the holding member to be made of a material with high toughness, so the holding force of the holding member does not decrease. , therefore,
The effect is that the fuel rods can be firmly supported within the support grid.

[Brief explanation of drawings]

1 to 6 are views showing an embodiment of the present invention, in which FIG. 1 is a plan view showing a part of the support grid, and FIGS. 2, 3, and 4 are views showing a strap, respectively. FIGS. 5 and 6 are plan views showing the lattice space and holding members, respectively, and FIGS. 7 and 8 are views showing an example of a conventional support lattice. FIG. 8 is a side sectional view showing the holding portion thereof. 1... Lattice space, 2... Strap, 4... Holding part (holding member), 6... Lattice space, 7... Horizontal strap (strap), 8... Vertical strap (strap), 9... Vertical strap (Strap), 10... Holding member, 20... Holding plate, 21
...Holding section.

Claims (1)

[Claims] 1 A plurality of straps assembled perpendicularly to each other to define a plurality of lattice spaces; and a plurality of straps extending into the plurality of lattice spaces through at least one wall of the lattice spaces, with both ends forming the walls of the lattice spaces. and a holding member fixed to the part, the holding member being
It consists of a pair of wavy holding plates arranged opposite to each other, and the pair of holding plates has portions that approach each other abutted against each other, and portions that are spaced apart from each other define an annular holding portion. , the axis of the holding part is arranged to match the axis of the grid space, and the abutting parts between two adjacent holding parts penetrate the wall of the grid space, and the abutting parts located at both ends A support grid characterized in that it is fixed to a wall of a grid space.