JP3020675B2 - Spent fuel storage rack and manufacturing method thereof - Google Patents

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 rack and a method of manufacturing the same, and more particularly, to a spent fuel storage rack suitable for installation in a fuel pool and a method of manufacturing the same.

[0002]

2. Description of the Related Art Conventional spent fuel storage racks include:
The structure is as shown in JP-A-55-1532. That is, as shown in FIGS. 7 to 9, a plurality of square pipes 23 are arranged at equal intervals, and
In order to improve the earthquake resistance, a reinforcing member 27 or an earthquake-resistant reinforcing member 25 is attached to a side surface between the square pipes 23 existing at the outermost periphery by welding.

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

Further, since the two side walls of the square pipe 23 exist 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 increases, and the building However, there is a problem that the load is large.

As a method for solving this problem, Japanese Patent Laid-Open Publication No.
There is a technique described in Japanese Patent Publication No. 296. In other words, by arranging a plurality of rectangular cylinders 21 in a checkered pattern as shown in FIG.
Furthermore, the space between the fuel assemblies is reduced only by the side wall of the rectangular cylinder 21, and the earthquake resistance is improved by welding a plurality of joining members 22 in the longitudinal direction of the rectangular cylinder 21.

In Japanese Unexamined Patent Publication No. 1-26991, as shown in FIG. 8, a flat horizontal plate 31 and a plurality of band-shaped vertical plates 32 are alternately laminated in a plurality of stages to form a lattice. ing.

In this method, a projection 33 formed on a strip-shaped vertical plate and a groove 34 formed on a flat horizontal plate are combined, and both corners of the combined portion are lightly fillet-welded with short leg lengths. 3
5 adhered.

[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 cylinders 21 arranged in a checkered pattern needs to be arranged so as to be substantially equal to the distance 21b between the inner wall surfaces of the rectangular cylinders 21. 21 and the radius of curvature of the two corner portions and the joining member 22
Is used to control the distances 21a and 21b between the two surfaces, but it is difficult to obtain the accuracy of the distance between the two surfaces because of the radius of curvature. In addition, since it is difficult to manufacture the rectangular cylinder 21 itself with high accuracy, it is necessary to make the rectangular cylinder 21 slightly larger with a margin in dimension. Square cylinder 21
Are provided at a plurality of positions in the longitudinal direction, but they are welded in a narrow portion of a corner portion and lack reliability. Further, since the main welding is provided with earthquake resistance, the amount of metal deposited in the fillet welding increases, and the deformation of the rack itself increases. In addition, in a portion where the joining member 22 is not provided at both corner portions of the adjacent rectangular cylinders 21, a gap is formed between the rectangular cylinders 21, and the shielding effect between the fuel assemblies is reduced.

In Japanese Patent Application Laid-Open No. 1-26991, the combination of the projection 33 and the groove 34 is very small, so that the earthquake resistance is weak and the processing of the projection 33 and the groove 34 takes time. Furthermore, since the fillet weld 35 is formed on both the upper and lower surfaces of the horizontal plate 31, automatic welding is impossible.

An object of the present invention is to provide a spent fuel storage rack which is simple to manufacture and can increase the storage density of spent fuel assemblies in a fuel pool, and a method of manufacturing the same.

[0011]

A first aspect of the present invention for achieving the above object is as follows.
A feature of the present invention is to have a width capable of arranging a plurality of spaces for accommodating one spent fuel assembly, a plurality of first partition plates having a plurality of slits formed therethrough, and And having a plurality of first protrusions disposed in the longitudinal direction on the first end face, and disposed between the two first partition plates,
And a plurality of second partition plates having a plurality of second protrusions arranged in a longitudinal direction on a second end surface different from the first end surface, and one of the second partition plates facing the first end surface of the second partition plate. The first protrusion inserted into the slit of the first partition plate was joined to one of the first partition plates on the side opposite to the surface of the one first partition plate facing the first end surface. A first welded portion, the second protrusion being inserted into the slit of the other first partition plate facing the second end face of the second partition plate, and the second partition plate and the other end being inserted; And a second welded portion joined at the intersection of the first partition plate and the space is formed between each of the second partition plates including the first welded portion and the second welded portion. It is in.

A feature of the second invention that achieves the above object is that the first partition plate and the second partition plate are made of stainless steel containing boron.

The features of the third invention for achieving the above object are as follows.
A first step of forming a plurality of first partition plates having a width capable of disposing a plurality of spaces for storing spent fuel assemblies of the body and having a plurality of slits formed therethrough; A plurality of first protrusions disposed in a longitudinal direction on a first end face facing one of the first partition plates, and a longitudinal direction on a second end face facing the other first partition plate. A second step of forming a plurality of second partition plates having a plurality of second protrusion portions disposed on the second partition plate; and forming the second protrusion portions of each of the second partition plates on the other first partition plate. A third step of inserting the second protrusion into the slit, and the second step of inserting the second protrusion into the slit of the other first partition plate with the respective second partition plate and the other first partition plate; A fourth step of welding intersections, and the first step of each second partition plate;
A fifth step of inserting a projection into the slit of the one first partition plate; and a step of inserting the first projection into the slit of the one first partition plate. A sixth step in which the projection is welded to the one first partition plate on the side opposite to the surface of the one first partition plate facing the first end surface, and The third to sixth steps are to be repeated until one of the spaces reaches a predetermined number, with one partition plate as the other first partition plate.

According to a fourth aspect of the present invention which achieves the above object, a third step of inserting the second projections of the respective second partition plates into slits of the other first partition plate; A fourth step of welding downward at the intersection of each of the second partition plates and the other first partition plate while the other is inserted into the slit of the other first partition plate; and A fifth step of inserting the first projections of the two partition plates into the slits of one of the first partition plates; and a step of inserting the first projection portions into the slits of the one first partition plate. And a sixth step of welding the first projection and the one first partition plate downward, wherein the third step is performed by using the first first partition plate as the other first partition plate. The sixth step is to be repeated until the space reaches a predetermined number.

[0015]

According to the first invention, the first projection provided on the first end surface of the second partition plate is inserted into the slit of one of the first partition plates, and is provided on the second end surface of the second partition plate. Since the second protrusion is inserted into the slit of the other first partition plate, the positioning of the second partition plate with respect to each first partition plate can be easily performed. In particular, since a plurality of the first and second protrusions exist in the longitudinal direction of the second partition plate, the positioning of the second partition plate in the longitudinal direction can be easily performed. Further, since the first welded portion is formed on the opposite side of the surface facing the first end face of one of the first partition plates, the joining between the one first partition plate and the second partition plate can be easily performed. From the above, it is possible to easily manufacture the spent fuel storage rack.

Further, in the first invention, the first projection is inserted into the slit of one first partition plate and the second projection is inserted into the slit of the other first partition plate. The dimensional accuracy between one partition plate and the other first partition plate and the positioning accuracy of these first partition plates are improved, and the occurrence of distortion of the second partition plate due to welding can be significantly suppressed. In addition, since each of the first partition plates and each of the second partition plates have a welded integral structure, a conventionally required earthquake-resistant band is not required. For these reasons, the storage density of the spent fuel assemblies in the fuel pool is significantly increased.

According to the second invention, the first partition plate and the second partition plate are made of stainless steel containing boron.
The effect of boron increases the neutron shielding effect.
For this reason, the interval between adjacent spent fuel assemblies in the spent fuel storage rack can be narrowed, and the storage density of the spent fuel assemblies can be further increased.

The third aspect of the invention has the same function and effect as the first aspect of the invention.

According to a fourth aspect of the present invention, the second projection is provided on the other first projection.
In the state inserted in the slit of the partition plate, the intersection of each second partition plate and the other first partition plate is welded downward, and the first
Since the first projection and the first partition are welded downward while the projection is inserted into the slit of the first partition, the first partition is moved upward from below in the horizontal direction. The spent fuel storage rack can be easily assembled.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A spent fuel storage rack according to one embodiment of the present invention will be described with reference to FIGS.

The spent fuel storage rack of this embodiment has a plurality of long partition plates 1 and a plurality of short partition plates 2. The long partition plate 1 and the short partition plate 2 are combined in a lattice pattern, and the distance between the partition plates, that is, the distance 13a between the long partition plates and the distance 13b between the short partition plates are substantially equal. This is because the interval between the cut portions (through holes) provided in the long partition plate 1 is equal to the width of the short partition plate 2.

As shown in FIG. 2, the long partition plate 1 has a plurality of lower cuts 6 and a plurality of upper cuts 7 in the longitudinal direction.
Having. The lower cuts 6 and the upper cuts 7 are alternately formed in a line. As shown in FIG. 3, the short partition plate 2 has a plurality of lower protrusions 8 in the longitudinal direction of one end surface and a plurality of upper protrusions 9 in the longitudinal direction of the other end surface.

FIG. 4 shows an intermediate stage of assembling the spent fuel storage rack of this embodiment. The lower projection 8 provided on one end surface of the short partition plate 2 is incorporated into the lower cut portion 6 of the long partition plate 1 placed in the horizontal direction. In this state, the long partition plate 1 and the short partition plate 2 are integrated by the lower welding metals 10 and 11 in which the respective intersections are welded from above. The short partition plate 2 stands upright with respect to the long partition plate 1. Lower weld metal 10, 11
In order to reduce welding deformation of the long partition plate 1 and the short partition plate 2, the left and right of the short partition plate 2 are intermittently respectively.
In particular, they are arranged in a staggered pattern. After the welding of one short partition plate 2 to the long partition plate 1 is completed, the lower convex portion 8 of another short partition plate 2 arranged in parallel with the short partition plate 2 is connected to the other of the long partition plate 1. At the intersection of the long partition plate 1 and the short partition plate 2 as described above.

After the welding of the short partitions 2 arranged in a row to the long partitions 1 is completed, the plurality of upper projections 9 of these short partitions 2 are placed above these short partitions 2. It is incorporated into a plurality of upper cut portions 7 of another long partition plate 1 to be positioned. The plurality of upper convex portions 9 of the short partition plate 2 are integrated with the other long partition plate 1 by an upper weld metal 12 which is formed by plug welding from the upper surface of the other long partition plate 1. The spent fuel storage rack is assembled by sequentially performing the above assembling procedure upward from the lower side.

Finally, the projections of the short partition plate 2 are assembled into the cut portions of the side partition plate 3 and the bottom plate 4 in the same manner as described above, and the short partition plate 2 is connected to the side partition plate 3 and the bottom plate 4. To be welded. After that, the support legs 5 of the rack are attached to the bottom plate 4 by welding to complete the spent fuel storage rack.

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

According to the structure of this embodiment, the distance between the partition plates, that is, the distance 13a between the long partition plate surfaces and the distance 13b between the short partition plate surfaces are determined by the upper and lower cuts 6 provided on the long partition plate 1. It is determined by the distance between the upper and lower cuts 6 and 7 in the adjacent row and the width of the short partition plate 2, all of which can be machined and have high precision. Further, upper and lower cuts 6 and 7 provided on the long partition plate 1 and upper and lower convex portions 9 and 8 provided on the short partition plate 2.
Are combined with each other, and the assembling can be performed in order from the bottom, and since all welding can be performed with downward welding having the best workability, distortion due to welding can be minimized.

Attachment of the long partition plate and the short partition plate is performed by plug welding of the projection of the short partition plate inserted into the cut portion provided on the long partition plate, but the insertion portion is restricted. As a result, deformation due to welding is suppressed. Further, the supply of air from the back side of the welding is cut off by plug welding, so that high-quality welding can be obtained without back sealing.

Further, since all the constituent members are plate members, the space for storing and assembling parts at the time of manufacture is small, and work can be performed.

FIG. 5 shows a spent fuel storage rack of this embodiment.
As shown in (1), production by automatic welding becomes possible.

The structure of the spent fuel storage rack of this embodiment is such that the protrusions 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 welded to the metal 10 and 1
It is excellent in earthquake resistance because it is integrated at 1 and 12 and the insertion part is restricted. Therefore, there is no need to install special seismic bands and supports, which are provided in the conventional spent fuel storage rack. As a result, the outer dimensions of the spent fuel storage rack itself can be reduced, and the storage density of the spent fuel can be increased in the entire space of the fuel storage pool.

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

The spent fuel storage rack is installed in a fuel storage pool (not shown) provided in the reactor building and filled with cooling water, and the adjacent long partition plate 1 and the adjacent short partition are provided. Spent fuel assemblies are inserted and stored in the space partitioned by the plate 2. A long partition plate 1 and a short partition plate 2 are provided between adjacent spent fuel assemblies.
Since the (neutron shielding wall) and the cooling water as a moderator are present, re-criticality of the spent fuel assembly can be prevented. Further, the fuel storage efficiency in the fuel storage pool can be increased by minimizing the distance between the spent fuel assemblies and reducing the outer dimensions of the entire rack to increase the space efficiency. Further, since it is not necessary to install a seismic band and a support, the weight of the spent fuel storage rack can be reduced, and the load on the reactor building can be reduced.

As described above, according to the present embodiment, it is possible to manufacture a high-precision and highly reliable spent fuel storage rack at a low cost while increasing the overall storage density. Further, the following effects can be achieved.

(1) Since the upper and lower cuts 6 and 7 provided on the long partition plate 1 and the upper and lower projections 9 and 8 provided on the short partition plate 2 are assembled and assembled, respectively, Dimensional accuracy is good, and furthermore, generation of distortion of the short partition plate 2 due to welding can be suppressed.

(2) In assembly welding, downward welding is possible, automatic welding can be applied, and high-quality products can be obtained with a small number of man-hours.

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

(4) Since it has a single-piece welded structure, it has excellent seismic resistance, so that a seismic band is not required, the external dimensions can be reduced, and the overall storage density can be increased. (5) The fuel itself is separated by a partition plate, and there is no gap between adjacent fuels, so that the radioactive shielding effect is excellent.

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

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

Another embodiment of the present invention will be described with reference to FIG. In this embodiment, the long partition plate 1 and the short partition plates 2, 2 '
Are arranged with two gaps between them.
The cooling water holding space 29 between the long partition plates 1 and the cooling water holding space 30 between the short partition plates 1 further retain the cooling water, thereby further improving the radiation shielding effect between the stored spent fuels. Can be Even in the case of assembling the partition plate having the two-sheet structure, the lower cut 6, the upper cut 7, the lower convex portion 8, and the upper convex portion 9 are assembled in the same manner as described above.

[0042]

According to the first and third aspects of the invention, the production is simple and the storage density of the spent fuel assemblies in the fuel pool can be increased.

According to the second aspect, the storage density of the spent fuel assembly can be further increased by the action of boron.

According to the fourth aspect of the present invention, since the downward welding is used, the spent fuel storage rack can be easily assembled from the lower part to the upper part in the horizontal direction of the first partition plate.

[Brief description of the drawings]

FIG. 1 is a perspective view of the entire configuration of a spent fuel storage rack according to a preferred embodiment of the present invention.

FIG. 2 is a configuration diagram of a long partition plate shown in FIG.

FIG. 3 is a perspective view of the short partition shown in FIG. 1;

FIG. 4 is an explanatory view showing an assembly procedure state of the partition plate shown in FIG. 1;

FIG. 5 is an explanatory view showing an example of an assembly operation state of the spent fuel storage rack shown in FIG. 1;

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

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

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

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

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

FIG. 11 is a perspective view of a spent fuel storage rack according to another embodiment of the present invention in which the partition plate has a double structure.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Long partition plate, 2 ... Short partition plate, 2 '... Double-structured short partition plate, 3 ... Side partition plate, 4 ... Bottom plate, 5 ... Rack support leg, 6 ... Lower cut, 7 ... Upper notch, 8: Lower convex portion, 9: Upper convex portion, 10: Lower weld metal, 11: Lower weld metal, 12: Upper weld metal, 13a: Distance between long partition plates, 13b: Distance between short partition plates Distance, 14: Automatic welding robot, 15: Lifting device, 21: Square cylinder, 21a: Distance between inner wall surfaces of the square cylinder, 21b: Distance between outer wall surfaces of the square cylinder,
22 joining member, 23 square pipe, 24 spacer, 2
5: Reinforcement member for earthquake resistance, 26: Support leg of rack, 27: Reinforcement member, 28: Support leg of rack, 29: Cooling water holding space between long partition plates, 30: Cooling water holding space between short partition plates Reference numeral 31 denotes a flat horizontal plate, 32 denotes a vertical strip, 33 denotes a projection formed in the vertical vertical plate, 34 denotes a groove formed in the horizontal horizontal plate, and 35 denotes a fillet weld.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Naoto Onda 3-1-1, Sachimachi, Hitachi-City, Ibaraki Pref. Hitachi, Ltd. Inside the Hitachi Plant (72) Inventor Masahiro Kobayashi 3-1-1, Sachimachi, Hitachi-City, Ibaraki No. 1 Hitachi, Ltd. Hitachi Plant (72) Inventor Tateo Takayama 2-2-2, Kochi-cho, Hitachi-shi, Ibaraki Hitachi Nuclear Engineering Co., Ltd. (72) Inventor Yoshio Yada 3-chome, Kochi-cho, Hitachi, Ibaraki No. 1 Hitachi, Ltd. Hitachi Plant (56) References JP-A-5-80188 (JP, A) JP-A-53-65597 (JP, A) (58) Fields investigated (Int. Cl. ⁷⁾ , DB name) G21C 19/07

Claims (7)

(57) [Claims] 1. A spent fuel storage rack comprising partition plates arranged in a grid pattern, wherein a plurality of spaces are formed, each of which is surrounded by the partition plates and accommodates a single spent fuel assembly. And a plurality of first partition plates having a width capable of disposing a plurality of the spaces and having a plurality of slits penetrating therethrough, and having a width of one space between the two first partition plates. A plurality of first protrusions arranged in a longitudinal direction on a first end face, and a plurality of second protrusions arranged in a longitudinal direction on a second end face different from the first end face. A plurality of second partition plates, the first projections inserted into the slits of the one first partition plate facing the first end face of the second partition plate, On the opposite side of the surface facing the first end surface, it was joined to one of the first partition plates. 1 welded portion, and the second projection is inserted into the slit of the other first partition facing the second end surface of the second partition, and the second partition and the other A second welded portion joined at an intersection with a first partition plate, wherein the space is formed between each of the second partition plates including the first welded portion and the second welded portion. Characterized spent fuel storage rack. 2. The spent fuel storage rack according to claim 1, wherein said first partition plate and said second partition plate are made of stainless steel containing boron. 3. A length of the first protrusion in a height direction of the fuel storage rack is longer than a length of the second protrusion, and a length of the first slit into which the first protrusion is inserted. 3. The spent fuel storage rack according to claim 1, wherein the length of the fuel storage rack in the height direction is longer than that of the second slit into which the second protrusion is inserted. 4. The first partition plate has a plurality of slit rows in which a plurality of slits are arranged in a height direction of the fuel storage rack, and each of the slit rows is a plurality of slits into which the first protrusion is inserted. And a plurality of second slits into which the second protrusions are inserted.
Any of the spent fuel storage racks. 5. A spent fuel storage rack comprising a plurality of partitions arranged in a grid pattern, wherein a plurality of spaces for accommodating one spent fuel assembly are formed in each of the partitions. A manufacturing method, comprising: a first step of forming a plurality of first partition plates having a width capable of disposing a plurality of the spaces and having a plurality of slits penetrating; and a width of one space; It has a plurality of first protrusions arranged longitudinally on a first end face facing one of the first partition plates, and is longitudinally arranged on a second end face facing the other first partition plate. A second step of forming a plurality of second partition plates having a plurality of second projection portions, and placing the second projection portions of each of the second partition plates in the slits of the other first partition plate. A third step of inserting, wherein the second protrusion is in front of the other first partition plate; A fourth step of welding the intersection of each of the second partition plates and the other first partition plate while being inserted into the slit, and the first projection of each of the second partition plates, A fifth step of inserting the one first partition plate into the slit, and the first projection portion being inserted into the slit of the one first partition plate, A sixth step of welding the one first partition plate to the other first partition plate on a side opposite to the surface facing the first end surface, A method for manufacturing a spent fuel storage rack, comprising repeating the third step to the sixth step as the other first partition plate until the space reaches a predetermined number. 6. A method for manufacturing a spent fuel storage rack according to claim 5, wherein the welding at the intersection of said second partition plate and said other first partition plate is downward welding. 7. A spent fuel storage rack comprising a plurality of partitions arranged in a grid pattern, each of which is surrounded by said partitions and each of which has a plurality of spaces for accommodating one spent fuel assembly. A manufacturing method, comprising: a first step of forming a plurality of first partition plates having a width capable of disposing a plurality of the spaces and having a plurality of slits penetrating; and a width of one space; It has a plurality of first protrusions arranged longitudinally on a first end face facing one of the first partition plates, and is longitudinally arranged on a second end face facing the other first partition plate. A second step of forming a plurality of second partition plates having a plurality of second projection portions, and placing the second projection portions of each of the second partition plates in the slits of the other first partition plate. A third step of inserting, wherein the second protrusion is in front of the other first partition plate; A fourth step of welding downward at an intersection between each of the second partition plates and the other first partition plate while being inserted into the slit; and the first projection of each of the second partition plates. A fifth step of inserting the first projection into the slit of the one first partition, and the first projection in a state where the first projection is inserted into the slit of the one first partition. And a sixth step of welding the one first partition plate downward and the third step to the sixth step, wherein the one first partition plate is the other first partition plate. A method of manufacturing a spent fuel storage rack, wherein the method is repeated until the space reaches a predetermined number.