JP3727214B2 - Spent fuel container basket structure - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a spent fuel container mainly used for transporting and storing spent fuel generated from a nuclear reactor core of a nuclear power plant, and more particularly for a spent fuel container that is provided inside and stores spent fuel. The present invention relates to a basket structure.
[0002]
[Prior art]
The spent fuel that has been used for a certain period in the reactor core in the nuclear power generation facility is removed from the core and temporarily stored in a spent fuel pool or the like. After the predetermined cooling period is completed, the reusable nuclear fuel material such as uranium and plutonium is recovered and reused, and is transported to a reprocessing factory for predetermined reprocessing. At this time, there is a possibility that the amount of spent fuel generated may exceed the reprocessing capacity due to the delay in construction of the reprocessing factory. Therefore, it is planned that the nuclear fuel cycle is made flexible by temporarily storing and storing spent fuel, which is an energy resource, before the reprocessing step.
[0003]
Methods for stably storing spent fuel inside or outside the nuclear power plant site include dry storage methods such as metal cask storage, vault storage, silo storage, and concrete cask storage, and wet storage methods for water pools. However, from the viewpoints of cost reduction and stable storage over a long period of time, dry storage, particularly metal cask storage, has attracted attention.
[0004]
In the metal cask storage system, a spent fuel container basket structure having a plurality of grid-like compartments for storing spent fuel assemblies is arranged inside a spent fuel container (cask), thereby The spent fuel assembly is stored while being partitioned one by one.
[0005]
At this time, the basket structure has a role of transferring heat radiation from the nuclear fuel material loaded in the fuel assembly to the spent fuel container and a role of absorbing radiation emitted from the nuclear fuel material to prevent criticality. For this reason, for example, a material in which a neutron absorber such as boron is added to a metal material having a high thermal conductivity such as aluminum is usually used as a material constituting the basket structure.
Furthermore, from the viewpoint of preventing the criticality, the basket structure can surely partition the fuel assemblies regardless of the posture of the spent fuel container, and if the spent fuel container is large for some reason. Even when an external force is applied and an impact load is applied, it is necessary to have a structure and strength that can sufficiently support the fuel assembly and its own weight.
Examples of such a basket structure include those described in JP-A-2-93698 and JP-A-6-094892, for example.
[0006]
In the basket structure described in JP-A-2-93698, a large number of disk members (disks) and semi-disk members (sleeves) having a plurality of openings corresponding to the plurality of sections are arranged in the axial direction and adjacent to each other. Spacer spacers are interposed for each gap between the disc members (or semi-disc members, hereinafter the same), and four rod members are provided so as to penetrate the spacers at four locations in the circumferential direction. Then, the bolt portions respectively provided at both ends of the rod member are exposed to the outside so as to penetrate through two disk members positioned at both ends in the axial direction among the plurality of disk members, and the exposed 2 By tightening and tightening one bolt part with a nut, the large number of disk members and the large number of spacers are firmly fixed and assembled into a single structure.
[0007]
In the basket structure described in Japanese Patent Laid-Open No. 6-094892, a first basket plate group composed of a plurality of basket plates aligned in parallel with each other in one direction, and a direction perpendicular to the one direction. And a second basket plate group consisting of a plurality of basket plates aligned in parallel with each other and alternately stacked in the vertical direction and assembled in a lattice shape, and the plurality of sections are formed by the gaps between the basket plates. . In each step of the laminated structure (that is, at a plurality of positions in the axial direction), a pair of substantially horizontal arc-shaped reinforcing plates are fixed to both ends of the first basket plate group or the second basket plate group. Further, connecting members extending over the entire length in the axial direction are arranged at a plurality of locations in the circumferential direction of the lattice-shaped outer peripheral portion, and all the first basket plate group and the second basket plate group are fastened and fixed to the connecting members by bolts. Thus, the whole is firmly fixed and assembled into one structure.
[0008]
[Problems to be solved by the invention]
However, the following problems exist in the above-described conventional technology.
[0009]
In the prior art described in JP-A-2-93698, a spacer is interposed between a large number of disk members, and the four rod members pass through it and are fastened with bolts. In addition to being extremely large, the assembly work is complicated and requires a lot of labor. In addition, since a large number of square openings are formed in the disk member, the distance (pitch) between the openings must be relatively large due to the strength of these members, and the number of partitions per unit area is small. There is also a problem of becoming.
[0010]
In the prior art described in Japanese Patent Laid-Open No. 6-094892, it is necessary to dispose a pair of horizontal reinforcing plates for each step, and dispose connecting members at a plurality of locations in the circumferential direction. In addition, it is necessary to bolt all the basket plate groups, and the number of parts becomes very large, and the assembling work is complicated and requires a lot of labor.
[0011]
A first object of the present invention is to provide a spent fuel container basket structure capable of reducing the number of parts.
[0012]
A second object of the present invention is to provide a spent fuel container basket structure capable of simplifying an assembling operation.
[0013]
[Means for Solving the Problems]
  (1) The firstAnd secondIn order to achieve the above object, the present invention provides a plurality of grid-shaped grids for storing spent fuel provided in a spent fuel container for storing spent fuel for storing or transporting spent fuel. A basket structure for a spent fuel container having a plurality of compartments, a plurality of basket plates assembled in a lattice shape and forming the plurality of compartments by a gap between each other, and an outer peripheral portion of the plurality of basket plates on the inner peripheral side A substantially cylindrical member for reinforcement is provided to reinforce the strength of the lattice structure by supporting and fixingThe outer circumferential portion of the plurality of lattice-like basket plates is inserted and supported in a groove or slit provided on the inner circumferential side of the reinforcing substantially cylindrical member, and the lower end portion of the groove or slit is inserted into the substantially cylindrical member for reinforcement. A stopper portion is formed at the lower end portion of the substantially cylindrical member for reinforcement, and a notch portion for fitting the stopper portion is provided at both ends of the lower edge portions of the plurality of basket plates. Formed and configured such that the plurality of basket plates can be inserted to the lower end of the substantially cylindrical member for reinforcement..
[0014]
  In the present invention, the outer peripheral portions of a plurality of basket plates assembled in a lattice shape are supported and fixed by a substantially cylindrical member for reinforcement, thereby supporting the outer peripheral portion having the weakest strength of the lattice structure and increasing its strength. It can be secured sufficiently. And by setting it as such a structure, the number of parts as a structural material is sufficient only with the some basket plate of a grid | lattice structure, and the substantially cylindrical member for reinforcement, and can be reduced significantly compared with a conventional structure.
[0016]
  Also,A basket plate that forms a rigid structure by inserting a lattice structure into slits or grooves and coupling them together to form a rigid structure without bolting or welding work as in the conventional structure. Can be reliably prevented. Therefore, the assembling work can be further simplified while ensuring the same strength and rigidity as the conventional structure.
[0017]
  (2In the above (1), and preferably, the plurality of basket plates are parallel to each other in a direction perpendicular to the one direction and a first basket plate group aligned in parallel to one direction. The second basket plate group aligned to each other are alternately stacked in the axial direction.
[0018]
As a result, it is possible to easily realize a structure that reliably holds the compartment for storing the fuel assembly in a rectangular shape.
[0019]
  (3)the above(2More preferably, the first basket plate group and the second basket plate group are provided with slits at portions intersecting at right angles to each other, and the slits are alternately engaged with each other in the axial direction. Laminated.
[0020]
As a result, even when assembling a plurality of basket plates in a lattice shape, simply laminating the slits of one basket plate group into the slits of the other basket plate group and engaging them easily in the axial direction (for example, the vertical direction) A structure can be realized. Thereby, the assembly work can be further simplified.
[0021]
  (4)In order to achieve the first and second objects, the present invention provides a spent fuel container for storing spent fuel for storing or transporting spent fuel. In a spent fuel container basket structure having a plurality of grid-like compartments for storage, a plurality of basket plates assembled in a lattice shape and forming the plurality of compartments by mutual gaps, and on the inner peripheral side By supporting and fixing the outer peripheral portions of the plurality of basket plates, a reinforcing substantially cylindrical member that reinforces the strength of the lattice structure is provided, and a groove or slit provided on the inner peripheral side of the reinforcing substantially cylindrical member, The plurality of basket plates are inserted and supported at the outer periphery, and the plurality of basket plates are arranged in parallel with each other toward one direction, and are perpendicular to the one direction. Direction And a second basket plate group aligned in parallel to each other Te, stacked axially disposed alternately with each other,The substantially cylindrical member for reinforcement has a structure that can be divided into a plurality of pieces in the axial direction, and the first basket plate group or the second group is provided in a groove provided on one end side or the other end side in the axial direction of each piece. The first basket plate group, the second basket plate group, and the substantially cylindrical member for reinforcement are integrated in the axial direction by fitting a protrusion provided on the end of the basket plate of the basket plate group.Shall be.
  ThisAs described in (1) above, the number of parts can be reduced and the assembling work can be simplified.
AlsoEven if it is assumed that a large external force is applied to the spent fuel container for some reason and an impact load in the axial direction is applied to the basket structure, the weight of each basket plate is dealt with through each protrusion. It can be received by each piece of the substantially cylindrical member for reinforcement, and it is possible to prevent the load from being transmitted to the basket plate on the most axial end side (for example, the uppermost stage) or the other end side in the axial direction (for example, the lowermost stage). . Accordingly, each basket plate can be thinned, so that the number of storage bodies in one spent fuel container can be increased.
[0022]
As a result, even if it is assumed that a large external force is applied to the spent fuel container for some reason and an impact load in the axial direction is applied to the basket structure, the weight of each basket plate is passed through each protrusion. It can be received by the corresponding piece of the substantially cylindrical member for reinforcement, and the load should not be transmitted to the basket plate at the axial endmost side (for example, the uppermost stage) or the axial direction other end side (for example, the lowermost stage). Can do. Accordingly, each basket plate can be thinned, so that the number of storage bodies in one spent fuel container can be increased.
[0023]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
[0024]
FIG. 1 is an exploded perspective view showing the structure of the basket structure according to the present embodiment.
[0025]
In FIG. 1, the basket structure according to the present embodiment is provided in a spent fuel container (for example, a cask) for storing a fuel assembly for storage or transportation of a spent fuel assembly (not shown). A plurality of basket plates 11a-d, 12a-d, 13a which are assembled in a lattice shape and form a plurality of lattice-shaped compartments (not shown) for accommodating spent fuel assemblies by the gaps between them. And the like, and a substantially cylindrical support rib 2 that reinforces the strength of the lattice structure 1 by supporting and fixing the outer peripheral portions of the plurality of basket plates 11a, 12a, and 13a on the inner peripheral side. .
[0026]
The basket plates 11a to 11d, 12a to 13d, 13a to 13d, etc. are shown only in this three-stage structure in FIG. 1 for the sake of simplicity, but are actually stacked in the same structure 4 below the basket plates 11a to 11d. It has a multistage structure with more than one stage. Needless to say, not only four sheets in each stage but also three or five or more may be arranged. Hereinafter, as appropriate, all of these are referred to as “basket plates 11a to 11d, 12a to 11d, 13a to 13d”.
[0027]
The basket plates 11a to 11d, 12a to 13d, and 13a to 13d are a group of uppermost vertical basket plates that are aligned in parallel in one direction (for example, the vertical direction, the same applies hereinafter) from the upper side to the lower side. 13, horizontal basket plate group 12, vertical basket plate group 11, horizontal basket plate group 12,... Horizontal basket plate group 12 aligned parallel to each other in a direction perpendicular to one direction (for example, the horizontal direction, and so on) Vertical basket plate group 11, vertical basket plates crossing at right angles, such as a lower horizontal basket plate group (not shown) aligned parallel to each other in a direction perpendicular to one direction The groups are alternately stacked in the axial direction (in this case, the vertical direction).
[0028]
Then, except for the basket plates 13a to 13d constituting the uppermost basket plate group 13 and the basket plate (not shown) constituting the lowermost basket plate group, the other basket plate groups 11, 12 and the like are constituted. The basket plates 11a to 11d and 12a to 12d all have the same axial dimension (in this case, the height in the vertical direction) H (see FIG. 1). The axial dimension of the basket plates 13a to 13d constituting the uppermost basket plate group 13 and the basket plate (same) constituting the lowermost basket plate group (not shown) is, for example, half (1/2) H.
At this time, for example, the vertical basket plate group 11 and the horizontal basket plate group 12 disposed on the upper side thereof are respectively provided with an upper slit 31 or a lower slit 32 at a portion intersecting at right angles, as shown in FIG. The slits 31 and 32 are engaged with each other to be alternately laminated in the axial direction. Other adjacent basket plate groups are also provided with slits having the same engagement relationship, and are stacked by being engaged with each other.
[0029]
However, only the lower slit 32 is provided in the basket plates 13a to 13d of the uppermost basket plate group 13, and only the upper slit 31 is provided in the basket plate of the lowermost basket plate group. The basket plate height of the uppermost and lowermost basket plate group is (1/2) H. Hereinafter, as appropriate, all the above-described various upper slits and lower slits are included, and simply referred to as “slits 31 and 32”.
[0030]
The slits 31 and 32 are provided at a pitch corresponding to one section for storing the fuel assembly, and the slit depth corresponds to the sum of the depths of the two slits 31 and 32 engaged with each other. It is determined to be about 1/2 of the height of the basket plate to be used (however, the uppermost and lowermost basket plate groups will be described later). For example, the slit engagement structure between the basket plate group 11 and the basket plate group 12 will be described as an example. The depth d1 (see FIG. 1) of the upper slit 31 such as the basket plates 11a to 11d and the basket plates 12a to 12d or the like. The total of d1 + d2≈ (1/2) H with the depth d2 of the lower slit 32 (see FIG. 1). FIG. 1 shows an example where d1 = d2≈ (1/4) H. The slits 31 and 32 of the basket plate groups other than the uppermost and lowermost stages have the same structure.
[0031]
The basket plate height of the uppermost and lowermost basket plate group is (1/2) H as described above, and the slit depth is (1/4) H. Therefore, in other words, the basket plates 13a to 13d of the uppermost basket plate group 13 are, for example, the lower halves 11aL to dL of the basket plates 11a to d of the basket plate group 11 (the virtual boundaries with the upper half are indicated by two-dot chain lines) The basket plate of the lowermost basket plate group is, for example, the upper half 12aU to dU of the basket plate 12a-d of the basket plate group 12 (imaginary with the lower half). It has substantially the same shape and dimensions as the boundary shown by a two-dot chain line (see FIG. 1).
[0032]
The basket plates 11a to 11d, 12a to 13d, and 13a to 13d are formed of a material containing a neutron absorbing material such as boron-added stainless steel, for example. In addition to the function of partitioning each fuel assembly, the above-described criticality prevention is performed. It comes to have both functions.
[0033]
On the other hand, the support ribs 2 are made of metal, and positions corresponding to both ends of the substantially cylindrical inner peripheral side (inner peripheral surface) basket plates 11a to d, 12a to d, 13a to d (16 locations in the circumferential direction). ) Are provided with grooves 33a-p having a width w (same as) substantially equivalent to the thickness t (see FIG. 1) of the basket plates 11a-d, 12a-d, 13a-d. -P is inserted and supported at both ends of the basket plates 11a-d, 12a-d, 13a-d (in other words, the outer peripheral portion of the grid-like structure 1) assembled in a lattice shape (details are given below). Later).
[0034]
In the above description, the support rib 2 is a substantially cylindrical member for reinforcement that reinforces the strength of the lattice structure by supporting and fixing the outer peripheral portions of the plurality of basket plates on the inner peripheral side according to the claims. Configure.
[0035]
Further, the uppermost basket plate group 13 and the vertical basket plate group 11 constitute a first basket plate group aligned in parallel with each other in one direction, and the lowermost basket plate group and the horizontal basket plate group 12. Constitutes a second basket plate group aligned parallel to each other in a direction perpendicular to one direction.
[0036]
The operation of assembling the basket structure of the present embodiment having the above-described structure is performed as follows.
[0037]
First, each basket plate of the lowermost basket plate group (having substantially the same shape and dimensions as the upper halves 12aU to dU of the basket plates 12a to 12d of the horizontal basket plate group 12 as described above), The support rib 2 is inserted into the grooves 33a to d and i to l on the inner peripheral side of the corresponding support rib 2 so as to be inserted from above (so as to maintain a parallel relationship with each other), and is slid downward as it is. It is arranged at a predetermined position in the axial direction.
[0038]
Next, the vertical basket plate group 11 is inserted into the upper portion of the upper basket 11 in the same manner as described above so that both ends thereof are inserted into the corresponding grooves 33e to h and m to p from above. At this time, as described above, the basket plates 11a to 11d are inserted so as to be orthogonal to the basket plates of the lowermost basket plate group, and are slid directly below the support rib 2. Then, the lower slits 32 of the basket plates 11a to 11d of the vertical basket plate group 11 are inserted and engaged with the upper slits 31 provided in the basket plates of the lowermost basket plate group, respectively. The basket plates 11a to 11d of the vertical basket plate group 11 are inserted and arranged downward until the side end portions come into contact with each other. As a result, the upper edge portions of the basket plates 11a to 11d of the vertical basket plate group 11 are positioned 2/2 above the upper edges of the basket plates of the lowermost basket plate group. A partial grid structure is formed, and a section for storing the fuel assembly is formed for the height H / 2 where each basket plate of the lowermost basket plate group exists.
[0039]
Thereafter, on the upper part of the partial lattice structure, the horizontal basket plate group 12 is made to be orthogonal to the basket plates 11a to d of the vertical basket plate group 11 in the same manner as described above, and the grooves 33a to d corresponding to both ends are provided. Insert it into i to l from above and slide it downward. And the lower slit 32 of each basket board 12a-d of the horizontal basket board group 12 is inserted and engaged with each upper slit 31 provided in each basket board 11a-d of a vertical basket board group, respectively. Thereby, in a state where the upper edge portions of the basket plates 12a to 12d of the horizontal basket plate group 12 are positioned H / 2 above the upper edges of the basket plates 11a to 11d of the vertical basket plate group 11, A section in which a partial lattice-like structure is formed by the lowermost basket plate group, the upper vertical basket plate group 11, and the upper horizontal basket plate group 12, and a fuel assembly of height H is stored. Is formed.
[0040]
Thereafter, in the same manner as described above, the operations of inserting the basket plates 11a to 11d of the vertical basket plate group 11 by one step and then inserting the basket plates 12a to 12d of the horizontal basket plate group 12 by one step are repeated alternately.
[0041]
And after arrangement | positioning of each basket board 12a-d of the horizontal basket board group 12 adjacent to the downward direction of the uppermost stage (namely, 2nd stage) is complete | finished, the uppermost basket board group 13 is further provided in the upper part. Similarly, each basket plate of the horizontal basket plate group 12 is inserted by inserting both ends into the corresponding grooves 33e to h, m to p while being orthogonal to the basket plates 112a to 112d of the horizontal basket plate group 12. The lower slits 32 of the basket plates 13a to 13d of the uppermost basket plate group 13 are inserted and engaged with the upper slits 31 provided in 12a to 12d, respectively.
As a result, the upper edge portions of the basket plates 13a to 13d of the uppermost basket plate group 13 are equal to the upper edge positions of the basket plates 12a to 12d of the horizontal sket plate group 12, and the uppermost basket plate group 13, The lower horizontal basket plate group 12, the lower vertical basket plate group 11,..., The horizontal basket plate group 12, the vertical basket plate group 11, and the lower basket plate group, the lattice-like structure 1 is completed. . That is, a fuel assembly storage section corresponding to the axial effective length of one fuel assembly is completed, each section is partitioned on all sides by a number of vertical and horizontal basket plates, and each section has a basket of the same height. It will be surrounded by a board.
[0042]
According to the basket structure of the present embodiment configured as described above, the following effects are obtained.
[0043]
(1) Reduction of the number of parts
According to the basket structure of the present embodiment, the position of each basket plate 11a-d, 12a-d, 13a-d is fixed by the support rib 2 and other basket plates orthogonal to each other. It is possible to make the entire system a rigid structure while keeping the storage area rectangular. In particular, the outer peripheral portion of the lattice structure 1 composed of a plurality of basket plates 11a to d, 12a to d, 13a to d and the like assembled in a lattice shape is supported and fixed by a substantially cylindrical support rib 2, thereby The outer peripheral portion having the weakest strength of the structure 1 can be supported to sufficiently secure the strength.
[0044]
And by setting it as such a structure, the number of parts is sufficient only with the some basket board 11a-d, 12a-d, 13a-d, etc. which comprise the lattice-like structure 1, and the support rib 2. FIG. Accordingly, a spacer is interposed between a large number of disk members, through which four rod members pass, and bolts are fastened and fixed. A conventional structure described in Japanese Patent Application Laid-Open No. 6-094892, in which a pair of horizontal reinforcing plates needs to be provided, and connecting members are provided at a plurality of locations in the circumferential direction, and all basket plate groups are bolted to the connecting members. Compared to, the number of parts can be greatly reduced. Moreover, since weight reduction can be achieved by this, the weight reduction of the whole spent fuel container is also realizable.
Furthermore, since the support rib 2 surrounds the periphery of the spent fuel assembly group, the support rib 2 can be provided with the radiation shielding function that is conventionally performed on the spent fuel container side. Therefore, the radiation shielding material on the container side can be omitted, and in this case, the number of parts can be further reduced.
[0045]
(2) Simplification of assembly work
Further, after the basket plates 11a to d, 12a to d, and 13a to d are alternately inserted in the vertical direction or the horizontal direction from above the support rib 2, the other basket plate group is inserted into the upper slit 31 of the one basket plate group. By simply inserting and engaging the lower slit 32, it is possible to easily form the lattice-like structure 1 that is an upper and lower laminated structure that can reliably keep the compartment for housing the fuel assembly in a rectangular shape. At this time, since the lattice-like structure 1 is connected to the support rib 2 through the grooves 33, a strong rigid structure can be obtained without performing bolt fastening or welding work as in the above two conventional structures. This can be realized, and the deformation of the basket plates 11a to 11d, 12a to 12d and 13a to 13d forming the compartments can be reliably prevented. That is, the assembling work can be further simplified while ensuring the same strength and rigidity as the conventional structure.
[0046]
Note that the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the technical idea. Hereinafter, the modified examples will be sequentially described.
[0047]
(1) Structure with stoppers above and below the support ribs
FIG. 2A is a partially broken exploded perspective view similar to FIG. 1 showing the structure during the assembly of the basket structure according to this modification, and FIG. 2B is a perspective view showing the structure after completion. It is.
[0048]
As shown in FIGS. 2 (a) and 2 (b), in this modification, welding or bolting is performed near the upper ends of the grooves 33a to 33p of the support rib 2 (that is, above the uppermost basket plate group 13). By providing the stopper member 41 by tightening, the position of the lower end portion of the grooves 33a to 33p is slightly above the lower end surface 2a of the support rib 2 (in other words, the vicinity of the support rib lower end surface 2a is left without being grooved). A stopper portion 42 is formed near the lower end of the grooves 33a to 33p of the support rib 2 (that is, below the lowermost basket plate group 14 (described later)).
[0049]
In this modification, as shown in FIG. 2 (a), the lattice-like structure 1 includes an uppermost basket plate group 13, a horizontal basket plate group 12, a vertical basket plate group 11, and an uppermost basket plate group that are substantially the same as those in the above embodiment. The lower basket plate group 14 is composed of four basket plate groups.
[0050]
Only the upper slit 31 is provided in the basket plates 14a to 14d of the lowermost basket plate group 14, and the height of each basket plate 14a to 14d is (1/2) H. The upper slits 31 are provided at a pitch corresponding to one section storing the fuel assembly, and the slit depth is (1/4) H. Moreover, the notch part 34 for fitting in the stopper part 42 formed in the groove | channel 33a-d and i-l lower end part mentioned above is formed in the lower edge part both ends of each basket board 14a-d. In addition, it fits into the stopper part 42 formed in the groove | channel 33e-h, m-p lower end part also to the lower edge part both ends of each basket board 11a-d of the vertical basket board group 11 of the 2nd step | paragraph from the bottom from the bottom. A notch 34 is formed for mating. By these cut portions 34, the basket plates 14a to 14d of the lowermost basket plate group 14 and the basket plates 11a to 11d of the upper vertical basket plate group 11 can be inserted to the lower end of the support rib 2. It has become.
[0051]
As is apparent from FIGS. 2A and 2B, in this modification, the lowermost basket plate group 14, the upper vertical basket plate group 11, the upper horizontal basket plate group 12, After the lattice structure 1 is completed by sequentially inserting the upper basket plate group 13 in the order of the upper basket plate group 13 through the grooves 33a to l on the inner peripheral side of the support rib 2, welding or bolting is finally performed near the upper end of the grooves 33a to 33p. A stopper member 41 is provided.
[0052]
In this modification, the structure is slightly complicated as compared with the above-described embodiment, because the stopper member 41 needs to be welded, bolted, and the like, but the four basket plate groups 13 and 12 having a lattice structure are used. , 11, 14 and the support rib 2 can be handled as a unit, the load on each basket plate 13a-d, 12a-d, 11a-d, 14a-d is received by the stopper 41 and lifted together. There is a possible effect.
[0053]
The stopper portion 42 is particularly suitable when the basket plate is not necessarily required at the upper end portion and the lower end portion of the fuel assembly from the viewpoint of preventing criticality, and the mass of the unnecessary basket material due to the provision of the cut portion 34 is provided. There is an effect that can be reduced.
[0054]
Needless to say, a member similar to the stopper member 41 may be provided in place of the stopper portion 42.
[0055]
(2) Structure in which the stopper above the support rib is replaced with a link member
FIG. 3A is a partially broken exploded perspective view showing a structure in the middle of assembling the basket structure according to this modification, and FIG. 3B is a perspective view showing the structure after completion.
[0056]
As shown in FIGS. 3 (a) and 3 (b), in the structure of the modified example (1), a groove is formed in the upper portion of the support rib 2 instead of providing the stopper member 41 by welding or bolting. A short and long support rib (support ring) 20 having no gap is fixed. In addition, in order to restrain rotation of the support ring 20, this support ring 20 and the support rib 2 are couple | bonded through the connection member which is not shown in figure.
[0057]
As is clear from FIGS. 3A and 3B, in this modification, the lowermost basket plate group 14, the upper vertical basket plate group 11, the upper horizontal basket plate group 12, After the lattice structure 1 is completed by sequentially inserting the upper basket plate group 13 in the order of the upper basket plate group 13 through the grooves 33a to l on the inner peripheral side of the support rib 2, the support ring 20 is fixed to the upper portion of the support rib 2 by welding or bolting And these are combined with a connecting member.
[0058]
By the way, in this kind of spent fuel container, even if it is assumed that a large external force acts on the spent fuel container for some reason and an impact load in the axial direction is applied to the basket structure, it is structurally sufficient. It is important to have safety strength. Therefore, when such an impact load is assumed, there is a possibility that the load receiving area in the support ring 20 is not sufficient in the structure shown in FIGS. 3A and 3B. FIG. ), The lower end surface of the support ring 20 is formed on the upper surface of the basket plates 13a to 13d of the uppermost basket plate group 13 and the basket plates 12a to 12d of the second horizontal basket plate group 12. The stopper member 43 may be fixed by welding or the like so as to be able to abut, thereby increasing the load receiving area in the support ring 20.
[0059]
(3) Structure in which the support rib can be divided into a plurality of axial directions
FIG. 4A is an exploded perspective view showing a state in the middle of assembling the basket structure according to this modification, and FIG. 4B is a perspective view showing the structure after completion.
[0060]
As shown in FIGS. 4 (a) and 4 (b), in this modification, the support rib 2 includes a plurality of pieces 21, 22, and 23 in the axial direction (that is, one piece 21 at the lowest stage, It has a structure that can be divided into one piece 23 in the uppermost stage and eleven pieces 22A, 22B) stacked and disposed between them.
[0061]
The lowermost piece 21 has, on one axial end side (in this case, the upper end side), grooves 35a to 35a parallel to eight positions corresponding to the basket plates 14a to 14d of the lowermost basket plate group 14. h is formed.
[0062]
In the uppermost piece 23, each of the uppermost basket plate group 13 (not shown, see FIG. 2, FIG. 3, etc. described above) is provided on the other axial end (in this case, the lower end). Grooves 38a to 38h (only part of which are shown in FIG. 4B) are formed at eight positions corresponding to the basket plates 13a to 13d (same as above).
[0063]
The eleven pieces 22 in the middle part are composed of six pieces 22A and five pieces 22B having different circumferential positions, and these pieces 22A and pieces 22B are alternately stacked one above the other. These pieces 22A and 22B have substantially the same structure itself, but are arranged so that their circumferential positions differ by 90 ° as shown in FIG.
[0064]
The piece 22A has eight positions corresponding to the basket plates 11a to 11d of the vertical basket plate group 11 (or the basket plates 13a to 13d of the uppermost basket plate group 13) on one end side in the axial direction (in this case, the upper end side). Are formed in each of the basket plates 14a to 14d of the lowermost basket plate group 13 (or the basket plates of the horizontal basket plate group 12) on the other axial end side (lower end side in this case). Grooves 36i to p (only part of which are shown in FIGS. 4A and 4B) are formed at eight positions corresponding to 12a to 12d.
[0065]
The piece 22B has grooves 36a 'to h' parallel to eight positions corresponding to the basket plates 12a to 12d of the horizontal basket plate group 12 on one end side in the axial direction (in this case, the upper end side) On the other end side in the direction (in this case, the lower end side), grooves 36 i ′ to p ′ parallel to eight positions corresponding to the basket plates 11 a to d of the vertical basket plate group 11 (FIGS. 4A and 4B). ) Is partially formed).
[0066]
Note that the height of the pieces 22A and 22B is half the height of the basket plates 11a to 11d and 12a to 12d of the vertical and horizontal basket plate groups 11 and 12, as shown in FIG.
[0067]
These pieces 21, 22A, 22B, and 23 are stacked and arranged so as to maintain the following circumferential positional relationship.
[0068]
(A) Lowermost piece 21 and upper piece 22A
For the grooves 35a, 35b, 35c, 35d, 35e, 35f, 35g, and 35h provided on the upper end side of the piece 21, grooves 36i, 36j, 36k, 36l, 36m, 36n, and 36o provided on the lower end side of the piece 22A. 36p are arranged so as to face each other in the vertical direction to form a slit 44 (see FIG. 4B).
[0069]
(B) Uppermost piece 23 and lower piece 22A
For each groove 38a, 38b, 38c, 38d, 38e, 38f, 38g, 38h provided on the lower end side of the piece 23, a groove 36a, 36b, 36c, 36d, 36e, 36f, 36g provided on the upper end side of the piece 22A. 36h are arranged so as to face each other in the vertical direction to form the slit 44.
[0070]
(C) Middle piece 22A and upper piece 22B
For each of the grooves 36a, 36b, 36c, 36d, 36e, 36f, 36g, and 36h provided on the upper end side of the piece 22A, the grooves 36i ', 36j', 36k ', 36l', and 36m provided on the lower end side of the piece 22B. ′, 36 n ′, 36 o ′, 36 p ′ are arranged so as to face each other in the vertical direction to form the slit 44.
[0071]
(D) Middle piece 22B and upper piece 22A
With respect to the grooves 36a ', 36b', 36c ', 36d', 36e ', 36f', 36g ', 36h' provided on the upper end side of the piece 22B, grooves 36m, 36n, 36o provided on the lower end side of the piece 22A , 36p, 36i, 36j, 36k, 36l are arranged to face each other in the vertical direction to form the slit 44.
[0072]
On the other hand, the basket plates 14a to d of the lowermost basket plate group 14, the basket plate 13 of the basket plate 13 of the uppermost basket plate group, and the basket plates 11a of the intermediate basket plate group 11 to the basket plate 11a to the middle portion. Projections 45 corresponding to the slits 44 described above are provided on both sides in the width direction on the basket plates 12a to 12d of the d and the horizontal basket plate group 12.
[0073]
2 and 3 and the like, the basket plates 14a to d of the bottom basket plate group 14, the basket plates 11a to d of the vertical basket plate group 11, and the horizontal basket plate group 12 in order from the bottom. When forming the lattice structure 1 by alternately laminating the basket plates 12a to 12d,..., The basket plate 13 of the basket plate 13 of the uppermost basket plate group, the projections 44 are inserted into the corresponding slits 44. It is designed to be fitted. The correspondence is as follows.
[0074]
(A) Lowermost piece 21 and upper piece 22A
The slits 44 formed by the grooves 35a to 35h provided on the upper end side of the piece 21 and the grooves 36i to 36p provided on the lower end side of the piece 22A are projected on the basket plates 14a to 14d of the lowermost basket plate group 14. The part 44 is fitted.
[0075]
(B) Uppermost piece 23 and lower piece 22A
The slits 44 formed by the grooves 38a-h provided on the lower end side of the piece 23 and the grooves 36a-h provided on the upper end side of the piece 22A have projections of the basket plates 13a-d of the uppermost basket plate group 13. 44 is fitted.
[0076]
(C) Middle piece 22A and upper piece 22B
In the slits 44 formed by the grooves 36a to h provided on the upper end side of the piece 22A and the grooves 36i 'to p' provided on the lower end side of the piece 22B, the basket plates 11a to d of the vertical basket plate group 11 are formed. The protrusion 44 is fitted.
[0077]
(D) Middle piece 22B and upper piece 22A
The slits 44 formed by the grooves 36a ′ to h ′ provided on the upper end side of the piece 22B and the grooves 36m to 36p and 36i to l provided on the lower end side of the piece 22A are formed in the basket plate 12a of the horizontal basket plate group 12. ˜d projection 44 is fitted.
[0078]
As can be seen from the above, by the projection 44, any basket plate 11a-d, 12a-d, 13a-d, 14-d is not only a direction perpendicular to the axial direction (in this example, the front-rear / left-right direction) The direction (in this example) is also restricted in the vertical direction.
[0079]
4 (a) and 4 (b), in this modification, the lowermost basket plate group 14 is incorporated in the lowermost piece 21, and further, the piece 22A, the vertical After assembling sequentially in the order of basket plate group 11, piece 22B, horizontal basket plate group 12, piece 22A, vertical basket plate group 11, ..., piece 22A, uppermost basket plate group 13, uppermost piece 23, Each support rib division piece 21, 22 </ b> A, 22 </ b> B, 23 is connected by a connecting member 5. Thereby, the divided pieces 21, 22A, 22B, 23 and the basket plate groups 11, 12, 13, 14 are all integrated in the axial direction.
[0080]
In this modified example, the structure is complicated compared to the above-described embodiment of the present invention shown in FIG. However, even if it is assumed that a large external force is applied to the spent fuel container for some reason and an impact load in the axial direction is applied to the basket structure, each basket plate 11a to d, 12a to d, 13a to d , 14a to d can be received by the corresponding pieces 21, 22A, 22B and 23 through the respective protrusions 45, respectively, and the axial endmost side (in this example, as in the structure of FIGS. It is possible to prevent the load from being transmitted to the basket plates 13a to 13d (see FIG. 3 and the like) at the uppermost stage and the basket plates 14a to 14d at the other end in the axial direction (the lowermost stage in this example). Accordingly, each basket plate 11a-d, 12a-d, 13a-d, 14a-d can be thinned, so that there is an effect that the number of storage bodies in the spent fuel container can be increased.
In addition, as shown to Fig.5 (a), the support rib axial direction division | segmentation structure (part of the pieces 21 and 22) by this modification and the structure (part of the support rib 2) of one embodiment of the present invention described above are used. A partially combined structure may be used. In this case, since the support rib axially divided structure is partially joined, the basket plate can be made thinner than the one embodiment of the present invention by the effect of the modified example (3), and the spent fuel can be achieved. There is an effect that the number of storage bodies per container can be increased. The boundary position between the support rib axially divided structure according to the combination mode and the modified example and the structure according to the embodiment of the present invention can be adjusted to an arbitrary position as necessary. Moreover, as shown in FIG.5 (b), it is good also as welding fixation after incorporating the boundary position. In this case, the connecting member 5 in the modified example (3) can be omitted.
[0081]
【The invention's effect】
According to the first aspect of the present invention, the outermost portion of the lattice-like structure that is weakest in strength is supported by the substantially cylindrical member for reinforcement and the strength thereof is sufficiently ensured. Only a plurality of basket plates having a structure and a substantially cylindrical member for reinforcement are sufficient, which can be greatly reduced as compared with the conventional structure. Moreover, since weight reduction can be achieved by this, the weight reduction of the whole spent fuel container is also realizable. Further, since the reinforcing substantially cylindrical member surrounds the periphery of the fuel assembly group, the radiation shielding function that has been performed on the spent fuel container side can be provided together with the reinforcing substantially cylindrical member. Therefore, the radiation shielding material on the container side can be omitted, and in this case, the number of parts can be further reduced.
[0082]
According to the second aspect of the present invention, it is not necessary to perform bolt fastening or welding work as in the conventional structure by inserting a lattice-like structure into the slits or grooves and coupling them together, thereby simplifying the assembly work. Can be
[Brief description of the drawings]
FIG. 1 is an exploded perspective view illustrating a structure of a basket structure according to an embodiment of the present invention.
FIG. 2 is a partially broken exploded perspective view showing a structure in the middle of assembly of a modified example in which stoppers are provided above and below a support rib, and a perspective view showing a structure after completion.
FIG. 3 is a partially broken exploded perspective view showing a structure in the middle of assembly of a modified example in which a stopper above a support rib is substituted with a link member, and a perspective view showing a structure after completion.
FIG. 4 is a partially broken exploded perspective view showing a structure in the middle of assembling of a modified example in which a support rib can be divided into a plurality of axial directions, and a perspective view showing a structure after completion.
5 is a structural diagram in which a support rib axially divided structure according to a modification of FIG. 4 is partially combined with the structure of the embodiment of FIG. 1, and a structural diagram in which boundary positions are assembled and fixed by welding.
[Explanation of symbols]
2 Support rib (substantially cylindrical member for reinforcement)
11 Basket board group (first basket board group)
11a-d Basket board
12 basket board group (second basket board group)
12a-d Basket board
13 Basket board group (first basket board group)
13a-d Basket board
14 Basket board group (second basket board group)
14a-d Basket board
21 pieces
22A piece
22B Peace
23 pieces
31 slit
32 slits
33a-p groove
35a-h slit
36a ~ p slit
36a'-p 'slit
38a-h slit
45 Protrusion

Claims (4)

A spent fuel container basket structure provided in a spent fuel container for storing spent fuel for storing or transporting spent fuel, and having a plurality of grid-like compartments for storing spent fuel In the body,
A plurality of basket plates assembled in a grid and forming the plurality of compartments by gaps between each other;
A substantially cylindrical member for reinforcement that reinforces the strength of the lattice structure is provided by supporting and fixing the outer peripheral portions of the plurality of basket plates on the inner peripheral side ,
While inserting and supporting the outer peripheral portions of the plurality of lattice-like basket plates in grooves or slits provided on the inner peripheral side of the substantially cylindrical member for reinforcement,
A lower end portion of the plurality of basket plates is formed by positioning a lower end portion of the groove or slit above a lower end portion of the substantially cylindrical member for reinforcement and forming a stopper portion at the lower end portion of the substantially cylindrical member for reinforcement. The spent fuel container is characterized in that a cut portion for fitting the stopper portion is formed at both ends, and the plurality of basket plates are inserted to the lower end portion of the substantially cylindrical member for reinforcement . Basket structure.   2. The spent fuel container basket structure according to claim 1, wherein the plurality of basket plates includes a first basket plate group aligned parallel to one another in a direction perpendicular to the one direction. A spent fuel container basket structure, wherein second basket plate groups aligned parallel to each other are alternately stacked in the axial direction. 3. The spent fuel container basket structure according to claim 2 , wherein the first basket plate group and the second basket plate group have slits at portions perpendicular to each other, and the slits are engaged with each other. Thus, the spent fuel container basket structure, which is alternately stacked in the axial direction. A spent fuel container basket structure provided in a spent fuel container for storing spent fuel for storing or transporting spent fuel, and having a plurality of grid-like compartments for storing spent fuel In the body,
A plurality of basket plates assembled in a grid and forming the plurality of compartments by gaps between each other;
A substantially cylindrical member for reinforcement that reinforces the strength of the lattice structure is provided by supporting and fixing the outer peripheral portions of the plurality of basket plates on the inner peripheral side,
While inserting and supporting the outer peripheral portions of the plurality of lattice-like basket plates in grooves or slits provided on the inner peripheral side of the substantially cylindrical member for reinforcement,
The plurality of basket plates include a first basket plate group aligned in parallel to one direction and a second basket plate group aligned in parallel to each other in a direction perpendicular to the one direction. , Alternately arranged in the axial direction alternately,
The substantially cylindrical member for reinforcement has a structure that can be divided into a plurality of pieces in the axial direction, and the first basket plate group or the second group is provided in a groove provided on one end side or the other end side in the axial direction of each piece. The first basket plate group, the second basket plate group, and the reinforcing substantially cylindrical member are integrated in the axial direction by fitting a protrusion provided on the end of the basket plate of the basket plate group. A spent fuel container basket structure.

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