JPH0236155Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a support grid for a nuclear reactor fuel assembly, and in particular, the present invention improves the strength of the support grid without increasing the thickness of the straps constituting the support grid. Concerning things that have increased.

[Conventional technology]

A fuel assembly loaded into a nuclear reactor is formed by arranging a large number of long fuel rods, in which a large number of short cylindrical fuel pellets are sealed, parallel to each other at regular intervals.

In this case, a support grid is used as a means to hold the fuel rods in this positional relationship.

As shown in FIG. 4, this support grid consists of a number of straps 4 made of rectangular heat-resistant thin plates.
1 are arranged vertically and horizontally to form a grid.

That is, each of these straps 41 is provided with slits 42 made by making a number of cuts at regular intervals in a direction perpendicular to its longitudinal direction, and the slits 42 of the straps 41 that constitute the vertical members constitute the horizontal members. The slits 42 of the straps 41 are butted against each other, and while the straps 41 are held in a positional relationship perpendicular to each other, the slits 42 of the straps 41 are
By inserting them into the grid, they are arranged vertically and horizontally to form a lattice-like structure.

Furthermore, a slot 44 is punched out approximately at the center of each of the straps at the position where each of the slits 42 is provided to improve the circulation of cooling water.

Further, a soft stop 43 having elasticity is formed by protruding to one side between the slots 44, and the top of the soft stop 43 is in contact with the fuel rod to support the fuel rod. A support protrusion 45 is provided.

Further, the soft stop 4 is located above and below the opposite side to the protruding side of the soft stop 43.
A hard stop 46 is provided which protrudes in a direction opposite to the direction of protrusion of the fuel rods 3 and rigidly supports the fuel rods.

When a fuel rod is inserted into each grid space of such a support grid, the fuel rod is pressed against the hard stop 46 by the elastic force of the soft stop 43 and supported at a predetermined position regulated by the hard stop 46.

Therefore, by installing these support grids at several locations in the longitudinal direction of the fuel rods, it is possible to construct a fuel assembly in which a large number of fuel rods are supported in parallel at regular intervals.

[Problem that the invention attempts to solve]

However, in such a support grid, a large number of slots 44 are provided along the longitudinal direction of the strap 41, and the areas between these slots 44 are provided with elastic soft stops 43 that protrude to one side. Because of this, it tends to be weak in strength.

In order to make this strength sufficient, the thickness of the strap 41 itself can be increased, but this would change the spring constant and lattice spacing of the soft stop 43 and hard stop 46, forcing a change in the design of the fuel assembly. Undesirable.

Furthermore, the thicker the plate, the more difficult it is to process the strap 41.

The object of the present invention is to obtain a support grid for a nuclear reactor fuel assembly that eliminates the above-mentioned drawbacks.

[Means for solving problems]

In the present invention, a reinforcing plate is attached to the opposite side of each strap from the protruding side of the soft stop, passing through each slot, and these reinforcing plates are fitted orthogonally to each other in each slot to form a lattice shape. It was formed in

[Effect]

By reinforcing the strength near the portions where the slots and soft stops are provided, a support grid with sufficient strength can be obtained without increasing the thickness of the strap itself.

〔Example〕

FIG. 1 is a partially cutaway perspective view showing a first embodiment of the present invention.

Reference numeral 1 in FIG. 1 indicates a strap made of a rectangular heat-resistant thin plate, and each of these straps 1 is provided with a number of slits 2 at regular intervals in a direction perpendicular to its longitudinal direction. The slit 2 of the strap 1 that constitutes the vertical member
The straps 1 and the slits 2 of the straps 1 constituting the horizontal member are butted against each other, and the straps 1 are held in a mutually orthogonal positional relationship and fitted into each other's slits 2, thereby being assembled vertically and horizontally to form a lattice shape.

Furthermore, a slot 4 is punched out at approximately the center of each of the straps 1 where the slits 2 are provided to improve circulation of cooling water.

Further, the portion located between each of the slots 4 is formed with an elastic soft stop 3 that protrudes to one side, and the top of the soft stop 3 is provided with a portion that contacts the fuel rod to support the fuel rod. A support protrusion 5 is provided.

Furthermore, hard stops 6 are provided at upper and lower portions on the opposite side to the protruding side of the soft stop 3, which protrude in a direction opposite to the protruding direction of the soft stop 3 and rigidly support the fuel rods.

Furthermore, a cutout 7 is provided at the widthwise center of each longitudinal end of the strap 1 and is perpendicular to the longitudinal direction, and a flat portion 8 is formed at a portion closer to both end surfaces of the notch 7. There is.

A reinforcing plate 9 made of a heat-resistant thin plate having a width narrower than the width of the slot 4 in the direction perpendicular to the longitudinal direction of the strap 1 and approximately the same length as the strap 1 is fixed to this flat part 8. has been done.

This reinforcing plate 9 is disposed on the opposite side to the protruding side of the soft stop 3, and at positions corresponding to the positions of the respective slits 2 provided in the strap 1 in the width direction of the reinforcing plate 9. A notch is provided, and the notch in the reinforcing plate 9 attached to the strap 1 constituting the vertical member and the notch in the reinforcing plate 9 attached to the strap 1 constituting the horizontal member are butted together. They are fitted into each other.

That is, each reinforcing plate 9 starts from the flat part 8 of the strap 1, passes one after another through the slot 4 of the strap group 1 perpendicular to the reinforcing plate 9, and reaches the other flat part 8 of the strap 1. The reinforcing plates are installed in the vicinity of each slot 4 and are fitted with orthogonal reinforcing plates.

When a fuel rod is inserted into each grid space of such a support grid, the fuel rod is pressed against the hard stop 6 by the elastic force of the soft stop 3 and supported at a predetermined position regulated by the hard stop 6.

Therefore, by installing support grids at several locations in the longitudinal direction of the fuel rods, it is possible to construct a fuel assembly in which a large number of fuel rods are supported in parallel at regular intervals.

According to this embodiment, since the reinforcing members 6 are attached between both ends of each strap 1, the strength of the strap 1 can be increased without increasing the thickness itself, and these reinforcing plates 9 Since they are combined vertically and horizontally to form a lattice-like structure, the entire support lattice is extremely strong.

FIG. 2 is a partially cutaway perspective view showing a second embodiment of the present invention.

In this embodiment, a reinforcing plate 29 corresponding to the reinforcing plate 9 in the first embodiment is provided with a corrugation 30 consisting of a large number of protrusions without notches, and the protruding height of this corrugation 30 is set at a hard stop 6.
The height of the protrusion is lower than the height of the protrusion.

Note that the other configurations are exactly the same as those of the first embodiment, so detailed explanation will be omitted.

In this embodiment, by providing the corrugations 30, the strength of the reinforcing plate 29 is further increased, and the strength of the entire support grid is further increased.

FIG. 3 is a partially cutaway perspective view showing a third embodiment of the present invention.

In this embodiment, a corrugation 40 consisting of a projection without a notch is provided in place of the hard stop 6 in the first embodiment, and a hard stop 36 is provided on the reinforcing plate 39 instead.

In this embodiment as well, the strength of the support grid can be made extremely high as in the second embodiment.

In addition, in each of the above embodiments, an example was shown in which the reinforcing plate is fixed by spanning both ends of the strap, but the present invention is not limited to this. A reinforcing member may be attached to the opposite side vertically or horizontally, and in short, this includes all structures in which reinforcing members are attached in the vicinity of slots and soft stops so as not to block the slots.

[Effect of idea]

As described in detail above, the present invention has a soft stop on the opposite side of each strap from which the soft stop protrudes.
Reinforcing plates are attached through each slot, and these reinforcing plates are fitted orthogonally to each other in each slot to form a lattice shape, so the reinforcing material allows the slots and soft stops to be By reinforcing the strength near the parts where the straps are installed, the strength of the support grid can be made sufficient without increasing the thickness of the strap itself. Furthermore, by forming the reinforcing plates in a grid shape, the support The entire lattice can be made extremely strong, and the reinforcing plates can be passed through the slots and combined in a lattice shape, making it easy to process and assemble the straps and reinforcing plates.

[Brief explanation of drawings]

FIG. 1 is a partially cutaway perspective view showing a first embodiment of the present invention, FIG. 2 is a partially cutaway perspective view showing a second embodiment of the present invention, and FIG. 3 is a partially cutaway perspective view showing a third embodiment of the present invention. FIG. 4 is a partially cutaway perspective view showing a conventional example. 1,41...Strap, 2,42...Slit, 3,43...Soft stop, 4,44...
Slot, 5, 45...Support protrusion, 6, 36, 4
6...hard stop, 7,47...notch,
8, 48... Flat portion, 9, 29, 39... Reinforcement plate, 30, 40... Corrugation.

Claims (1)

[Claims for Utility Model Registration] A rectangular thin plate is provided with slits by making a number of cuts at regular intervals in a direction perpendicular to its longitudinal direction, and the thin plate is provided with slits approximately in the center of the position where each slit is provided. forming a strap by punching out a plurality of straps to provide a large number of slots corresponding to each of the slits, and further protruding a portion of the thin plate between the slots to one side to provide an elastic soft stop; In a support lattice of a reactor fuel assembly formed by using a large number of straps and forming a lattice by fitting the slits of these straps into each other and assembling them vertically and horizontally, a side opposite to the protruding side of the soft stop of each of the straps. A nuclear reactor fuel assembly characterized in that reinforcing plates are attached to the sides of the reactor by penetrating each of the slots, and these reinforcing plates are fitted orthogonally to each other in each of the slots to form a lattice shape. Support grid.