JPH0580189A - Used fuel storing rack and its manufacture - Google Patents

Abstract

(57) [Abstract] [Purpose] The present invention is a spent fuel which is excellent in seismic resistance and shielding effect by combining a plurality of partition plates in a grid pattern, and has high space efficiency, high precision, high quality and low cost. The purpose is to easily provide a storage rack. According to the present invention, a long partition plate of a spent fuel storage rack is provided with a plurality of cuts, and a short partition plate provided with a convex portion which can be inserted into the cuts is combined with the long partition plate in a grid pattern. , The intersection is integrated. According to the present invention, it is possible to manufacture a spent fuel storage rack that is highly accurate and highly reliable at low cost while increasing the overall storage density.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spent fuel storage facility of a nuclear power plant, which has excellent shielding effect, seismic resistance and space efficiency, and stores spent fuel assemblies at high density.
The present invention relates to a spent fuel storage rack that is highly accurate, high quality, and inexpensive, and a method for manufacturing the same.

[0002]

2. Description of the Related Art As a conventional spent fuel storage rack,
It has a structure as disclosed in Japanese Patent Laid-Open No. 55-1532. That is, as shown in FIGS. 7 to 9, a plurality of square pipes 23 are arranged at equal intervals and the spacers 2 are provided between the square pipes 23.
4, the reinforcing member 27 or the earthquake-proof reinforcing member 25 is attached by welding to the side surface between the square pipes 23 existing on the outermost periphery in order to improve the earthquake resistance.

In this structure, the spacers 24 are provided between the square pipes 23 to connect the square pipes 23 to each other, so that the distance between the fuel assemblies is large and space efficiency is reduced.

Further, since the side walls of the two square pipes 23 are present between the fuel assemblies, and the reinforcing member 27 is attached from the viewpoint of earthquake resistance, the weight of the spent fuel storage rack itself becomes heavy, and the building is constructed. There was a problem that the load against was large.

As a solution to this problem, Japanese Patent Laid-Open No. 1-280
There is a technology described in Japanese Patent No. 296. That is, as shown in FIG. 6, by arranging a plurality of rectangular cylinders 21 in a checkerboard pattern, the spacers 24 are not required and space efficiency is improved.
Further, only the side wall of the rectangular tubular body 21 is provided between the fuel assemblies, and the weight is reduced. Further, by welding a plurality of joining members 22 in the longitudinal direction of the rectangular tubular body 21, the seismic resistance becomes excellent.

Further, in Japanese Unexamined Patent Publication No. 1-269091, as shown in FIG. 8, flat plate-shaped horizontal plates 31 and a plurality of strip-shaped vertical plates 32 are alternately laminated in a plurality of stages to form a grid pattern. ing.

This is a combination of a projection 33 formed on a strip-shaped vertical plate and a groove 34 formed on a flat plate-shaped horizontal plate. Further, both corners of the combined portion are welded with a short leg length and mild fillet welding. Three
It adheres by 5.

[0008]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
In the publication, the distance 21a between the outer wall surfaces of the rectangular tubular bodies 21 arranged in a checkered pattern needs to be arranged to be substantially equal to the distance 21b between the inner wall surfaces of the rectangular tubular body 21, and the adjacent rectangular tubular bodies are arranged. 21 and the joint member 22
Although the two-sided distances 21a and 21b are suppressed by using, it is difficult to obtain the accuracy of the two-sided distance because of the radius of curvature. Further, since it is difficult to manufacture the square tubular body 21 itself with high precision, it is necessary to make the square tubular body 21 a little larger with a dimensional allowance. Square tube 21
Although the joining member 22 is provided at a plurality of positions in the longitudinal direction, it is welded at the narrow portion of the corner portion and lacks reliability. Furthermore, since the main welding has seismic resistance, the amount of deposited metal in fillet welding increases and the deformation of the rack itself increases. In addition, in the portions where the joining members 22 are not provided at both corners of the adjacent square tubular bodies 21, a gap is formed between the square tubular bodies 21, and the shielding effect between the fuel assemblies is reduced.

Further, in Japanese Patent Application Laid-Open No. 1-269091, since the combined size of the projection 33 and the groove 34 is very small, the seismic resistance is weak and it takes time to process the projection 33 and the groove 34. Further, since the fillet welds 35 are applied to both the upper and lower surfaces of the horizontal plate 31, automatic welding is impossible.

In order to solve the above problems, the present invention compensates for the above-mentioned drawbacks of the prior art, and by combining a plurality of partition plates in a grid pattern, it is excellent in earthquake resistance and shielding effect, space efficiency is improved and high precision is achieved. The purpose is to easily provide a spent fuel storage rack of high quality and low cost.

That is, the conditions required for the spent fuel storage rack are as follows.

The spent fuel storage rack is installed in a fuel pool (not shown) filled with cooling water, and the spent fuel assembly is inserted and stored in a partitioned space provided in the rack. ing.

It is necessary to prevent the re-criticality of the spent fuel assemblies due to the presence of a side wall (neutron shielding wall) and a gap filled with cooling water as a moderator between the spent fuel assemblies. (Screening effect).

Further, it is necessary to increase the fuel storage efficiency in the fuel pool by reducing the distance between the spent fuel assemblies as much as possible and reducing the outer dimensions of the entire rack to improve the space efficiency.

In order to reduce the distance between the spent fuel assemblies, it is necessary to improve the dimensional accuracy of the fuel storage rack.

Structurally, a structure having excellent earthquake resistance is required, and it is necessary to further reduce the weight and reduce the load on the building.

[0017]

In order to achieve the above object, in a spent fuel storage rack in which partition plates are combined in a grid pattern, machining of the positioning of the interplanar distance of the partition plates is performed without welding. The accuracy was improved as a method of combining by crossing. Since the partition plate is integrated by a combination structure of the partition plates themselves without using a conventional joining member, it has excellent earthquake resistance, and it is not necessary to attach an outermost earthquake resistant band in the final shape. Therefore, it is possible to reduce the outer dimensions of the rack itself, improve the overall fuel storage efficiency, and reduce the weight and the load on the building.

Since the partition plates are assembled on the lattice, the space into which the spent fuel assemblies are inserted is manufactured without a gap, and the spent fuel assemblies are completely partitioned by the side walls. The shielding effect, which is the most important item of the fuel storage rack, is sufficient.

Further, in order to enhance the shielding effect, it is possible to assemble two partition plates in parallel and hold the coolant in the gap.

As a manufacturing procedure thereof, assembling can be carried out in order from one direction, and by using downward welding, automatic welding can be adopted and a highly accurate, high quality and inexpensive spent fuel storage rack can be obtained.

[0021]

[Function] The notch provided on the long partition plate is machined, while the width and the convex portion of the short partition plate are also machined. By combining them, the face-to-face distance of the partition plate can be accurately obtained. Manufactured. The long partition plate and the short partition plate are attached by plug welding the convex part of the short partition plate inserted into the notch provided on the long partition plate, but welding is done because the insertion part is constrained. Deformation due to is suppressed. Further, because of the plug welding, the supply of air from the back side of the welding is cut off, and high quality welding can be obtained without back sealing.

Since each member has a plug-in structure, it has excellent seismic resistance, and the conventional seismic support is unnecessary, which reduces the number of constituent members and the external dimensions, thus reducing the overall size. The storage density can be increased.

As a manufacturing procedure, assembling can be performed in order from one direction, and automatic welding can be performed as shown in FIG.

Further, in the past, a plurality of joining members were welded to each other in the longitudinal direction to join the rectangular cylinders, but a gap was formed between the rectangular cylinders except for the joint portion. In the present invention, since all are surrounded by the partition plate and there is no gap, the shielding effect between the fuels is excellent.

Furthermore, it is possible to improve the shielding effect by assembling two partition plates in parallel and holding a coolant in the gap.

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment according to the present invention will be described with reference to FIGS.

FIG. 1 is an overall perspective view of a spent fuel storage rack according to the present invention, in which a long partition plate 1 and a short partition plate 2 are combined in a grid pattern so that the distance between the partition plates, that is, the surface of the long partition plate. The cut portion and the width of the short partition plate 2 are set so that the distance 13a and the distance between the surfaces of the short partition plates 13b are substantially equal.

FIG. 2 is a bird's-eye view showing an example of the long partition plate 1 according to the present invention, which has a plurality of lower cut portions 6 and upper cut portions 7 in the longitudinal direction.

FIG. 3 is a bird's-eye view showing an example of the short partition plate 2 according to the present invention, which has a plurality of lower projections 8 and upper projections 9 in the longitudinal direction.

FIG. 4 shows an assembling state of the partition plate in the rack manufacturing stage.

Lower cut portion 6 provided on the long partition plate 1
Insert the lower projection 8 provided on the short partition plate 2 into the
The intersections of the long partition plate 1 and the short partition plate 2 are integrated by the lower welded metals 10 and 11 welded.

The lower deposited metals 10 and 11 are intermittently arranged in a zigzag pattern on the left and right sides of the short partition plate 2 in order to reduce welding deformation.

Further, the upper convex portion 9 provided on the short partition plate 2 is inserted and incorporated into the upper notch portion 7 provided on the long partition plate 1, and this portion is plug welded to the upper weld metal 1
It is integrated in 2. A spent fuel storage rack is constructed by sequentially performing the above assembly procedure from the lower side.

Finally, the side partition plate 3 and the bottom plate 4 are inserted and welded similarly to the partition plate, and the supporting legs 5 of the rack are attached by welding to complete the spent fuel storage rack.

In the case of such a structure, the distance between the partition plates, that is, the distance 13a between the long partition plate surfaces and the distance between the short partition plate surfaces 1
3b is the upper and lower cuts 6 provided on the long partition plate 1,
Although it is determined by the distance between 7 and the upper and lower cuts 6 and 7 in the adjacent row and the width dimension of the short partition plate 2, both of them can be machined and highly accurate. Further, the upper and lower cuts 6 and 7 provided on the long partition plate 1 and the upper and lower convex portions 9 and 8 provided on the short partition plate 2 are combined with each other, and the assembly can be performed in order from the bottom. Since all of the welding can perform downward welding with the best workability, distortion due to welding can be minimized.

Further, since all the constituent members are plate materials, the space for storing and assembling the parts at the time of manufacturing can be reduced and the work can be performed.

FIG. 5 shows an embodiment of the assembling work state of the spent fuel storage rack according to the present invention, which can be manufactured by automation.

The structure is such that the convex portions 8 and 9 of the short partition plate 2 inserted into the cut portions 6 and 7 provided in the long partition plate 1 are integrated by the weld metals 10, 11 and 12. Since it is restrained, it has excellent earthquake resistance.

Therefore, it is not necessary to install a special seismic band and support. As a result, the outer dimensions of the spent fuel storage rack itself can be made smaller, so that the storage density can be increased in the entire storage pool space.

Further, since the partition plates are assembled in a lattice shape and there is no gap between the partition plates, the stored fuel is completely partitioned. As a result, the radiation shielding effect between each fuel is excellent.

The shielding effect can be further enhanced by using stainless steel containing boron as a neutron absorber as the material of the long partition plate 1 and the short partition plate 2.

In another embodiment, the long partition plate 1 and the short partition plates 2 and 2'are each provided with two gaps, and the cooling water holding space 29 between the long partition plates and the short partition plates are provided. By holding the cooling water in the cooling water holding space 30, the radiation shielding effect between the stored fuels can be further enhanced. When assembling the partition plate having the two-layer structure, the lower notch 6, the upper notch 7, the lower convex portion 8 and the upper convex portion 9 are combined and manufactured in the same manner as described above.

[0043]

As described above, according to the present invention, it is possible to manufacture a spent fuel storage rack which is highly accurate and highly reliable at a low cost while increasing the overall storage density. Furthermore, the following effects can be achieved.

(1) Since the partition plates are provided with the notches for assembly, the dimensional accuracy between the partition plates is good, and the distortion due to welding can be suppressed.

(2) Assembly welding can be performed downward, automatic welding can be applied, and high quality products can be obtained with a small number of steps.

(3) Since the frame plate is used, the space for storing and assembling the parts at the time of manufacturing can be reduced.

(4) Since it has a welded integral structure and is excellent in earthquake resistance, no earthquake-proof band is required, the external dimensions can be reduced, and the overall storage density can be increased.

(5) The fuel itself is individually partitioned by partition plates, and there is no gap between adjacent fuels, and the radiation shielding effect is excellent.

(6) It is not necessary to manufacture a rectangular cylindrical body which is a special manufacturing method, and it is a simple plate material assembling structure and can be manufactured with a small number of manufacturing steps.

(7) An excellent radiation shielding effect can be obtained by attaching two partition plates in parallel at equal intervals to form a double structure and retaining cooling water in the space.

[Brief description of drawings]

FIG. 1 is an explanatory view showing an embodiment of an overall perspective view of a spent fuel storage rack of the present invention.

FIG. 2 is an explanatory view showing the shape of a long partition plate of a spent fuel storage rack.

FIG. 3 is an explanatory view showing the shape of a short partition plate of a spent fuel storage rack.

FIG. 4 is an explanatory view showing a procedure of assembling a partition plate.

FIG. 5 is an example of an assembly work state of a spent fuel storage rack according to the present invention.

FIG. 6 is a partial plan sectional view of a conventional spent fuel storage rack.

FIG. 7 is a partial plan sectional view of a conventional spent fuel storage rack.

FIG. 8 is a partial plan sectional view of a conventional spent fuel storage rack.

FIG. 9 is an overall perspective view of an embodiment of a conventional spent fuel storage rack.

FIG. 10 is an overall perspective view of an example of a conventional spent fuel storage rack.

FIG. 11 is an explanatory view showing an embodiment in which the partition plate has a double structure.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Long partition plate, 2 ... Short partition plate, 2 '... Short partition plate with a double structure, 3 ... Side partition plate, 4 ... Bottom plate, 5 ... Rack support leg, 6 ... Lower notch, 7 ... Upper notch, 8 ... Lower convex portion, 9 ... Upper convex portion, 10 ... Lower weld metal, 11 ... Lower weld metal, 12 ... Upper weld metal, 13a ... Long partition plate surface distance, 13b ... Short partition plate surface Distance, 14 ... Automatic welding robot, 15 ... Elevating device, 21 ... Square tube, 21a ... Distance between inner wall surfaces of square tube, 21b ... Distance between outer wall surfaces of square tube,
22 ... Joining member, 23 ... Square pipe, 24 ... Spacer, 2
5 ... Seismic reinforcing member, 26 ... Rack supporting leg, 27 ... Reinforcing member, 28 ... Rack supporting leg, 29 ... Cooling water holding space between long partition plates, 30 ... Cooling water holding space between short partition plates , 31 ... Flat plate horizontal plate, 32 ... Vertical strip plate, 33 ... Protrusions formed on the vertical strip plate, 34 ... Grooves formed on the flat horizontal plate, 35 ... Fillet weld.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yasukata Tamai 3-1-1, Saiwaicho, Hitachi-shi, Ibaraki Hitachi Ltd. Hitachi factory (72) Inventor Naoto Onda 3-chome, Hitachi-shi, Ibaraki 1-1 Hitachi Ltd., Hitachi Works, Hitachi Plant (72) Inventor Masahiro Kobayashi 3-1-1, Saiwaicho, Hitachi City, Ibaraki Hitachi Ltd., Hitachi Works, Hitachi Plant (72) Takeo Takayama Hitachi City, Ibaraki Prefecture 3-2, Sachimachi Hitachi New Clear Engineering Co., Ltd. (72) Inventor, Yoshio Yada 3-1-1, Sachimachi, Hitachi City, Ibaraki Hitachi Ltd., Hitachi Works

Claims (4)

[Claims] 1. A spent fuel storage rack comprising partition plates combined in a grid pattern, wherein a long partition plate is provided with a plurality of cuts, and a short partition plate provided with a convex portion that can be inserted into the cuts, and the long strip. A spent fuel storage rack characterized by combining partition plates in a grid pattern and integrating the intersections. 2. A method of manufacturing a spent fuel storage rack comprising a combination of partition plates arranged in a grid pattern, wherein a long partition plate is placed horizontally, a cut portion is provided on the long partition plate, and a short length is provided at the cut portion. A plurality of short partition plates are vertically inserted by inserting into the convex portion of the partition plate, and the intersections thereof are welded downward, and at the other convex portion of the plurality of short partition plates, another long partition plate is attached. A method for manufacturing a spent fuel storage rack, characterized in that cut portions are combined, the cut portions are plug-welded downward, and the plug welding procedure is repeated. 3. The method for manufacturing a spent fuel storage rack according to claim 2, wherein after the cut portion and the convex portion of the partition plate are inserted, they are fixed by welding and provided on the spent fuel storage rack. A method for manufacturing a spent fuel storage rack, characterized in that the seismic resistant member is removed and the four directions are surrounded by partition plates without any gaps. 4. The method for manufacturing a spent fuel storage rack according to claim 2, wherein the two long partition plates and the short partition plates are arranged in parallel with each other with gaps at equal intervals.
A method for manufacturing a spent fuel storage rack, characterized in that a partition plate having the cutouts and the protrusions is assembled and cooling water is held in the gaps.