JP2001281392A - Basket for recycle fuel transport and storage container and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a basket for recycle fuel transport and storage container capable of satisfactorily retaining the pitch precision between fuel storage cells, moderating the thermal stress at a using temperature, easy to assemble and improved in compactness. SOLUTION: This basket has a lattice plate 22 having a projection part and a slit formed thereon, an intersection for inserting the projection part of one lattice plate to the slit of the other lattice plate, and a plurality of grids formed by combining four intersections, the lattices 22 are constituted shorter than the opposed distance of the inside walls of a vessel 4 for housing them. A fixing plate 30 slidable along the longitudinal direction is combined with the end part of the lattice 22 with a fixed fastening force, and the fixing plate is allowed to abut on the inside wall of the vessel 4, thereby, the lattice is fixed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recycled fuel transport storage container basket for storing a recycled fuel assembly taken out of a nuclear reactor in a recycled fuel transport storage container, and more particularly to a temperature condition, weight and the like thereof. The present invention relates to a basket for a storage container for transporting recycled fuel, which has improved density and processability in consideration of the above, and a method for manufacturing the same.

[0002]

2. Description of the Related Art Generally, in a nuclear power plant,
After operating the reactor for a certain period, the recycled fuel removed from the core is temporarily stored in the recycled fuel rack installed in the recycled fuel storage pool until reprocessing, and then stored in the basket of the recycled fuel transport storage container. This is cooled to remove the decay heat of the fuel. In recent years, there has been a demand for increasing the storage capacity by effectively utilizing the space in the basket of the recycled fuel transport storage container. For this purpose, for example, a material having a large neutron absorption capacity is interposed between the stored fuels to increase the fuel mutual capacity. This material is used as a lightweight and strong member to support recycled storage fuel during various events during transportation and storage, while reducing the distance between storage fuels while maintaining the seaside nature of the seawater. A basket of recycle fuel transport storage containers that can increase the fuel consumption has been proposed.

The recycle fuel rack installed in the recycle fuel storage pool is fixed only on the floor of the recycle fuel pool, is self-supporting and structurally designed as a storage rack having a seismic strength fixed at the lower end, and is irradiated with pool water. As the design condition is that it is used at a normal temperature of 30 ° C, the basket of the recycled fuel transport storage container is inserted into the container, and the support portion of the basket is independent on the side and bottom surfaces. It does not do. For long-term storage, radiation is shielded with the material of the recycled fuel transport storage container. For cooling and heat removal of the recycled fuel, a gas with good thermal conductivity (such as helium) is sealed in the container and stored in a dry state. Air cooling. For this reason, the design environmental condition of the basket of the recycled fuel transport storage device is a temperature of about 200 ° C., which is in an area where thermal expansion needs to be considered. Further, the recycled fuel transport storage container and its basket are required to be reduced in weight in order to increase the number of storage containers in a dense manner due to restrictions on handling during transportation.

[0004] A typical example of such a basket for transporting and storing recycled fuel is a boron-containing aluminum alloy containing boron having excellent neutron absorption capacity and having good structural strength, and having a space between the stored fuels of one. There is a so-called lattice-plate-shaped fuel storage cell structure in which two boron-added aluminum alloys are interposed. Since these conditions are satisfied and the weight and strength are good, the conventional
As shown in FIG. 2 and FIG.
Is passed through a spacer 3 which penetrates through the insertion holes 3a in a lattice-like arrangement on a plate, and a plurality of the spacers are arranged at intervals in the longitudinal direction of the rectangular cylinder 2 to form a lattice arrangement.

FIG. 9 is a plan view and FIG.
As shown in a partially cut-away side view taken along arrow -E and a partially enlarged plan view of FIG. 11, a basket 1 constituted by a combination of a fuel rack type rectangular cylinder 2 is known.
The basket 1 is mounted and accommodated in a recycle fuel transport storage container 4, and the rectangular cylindrical body 2 is fixedly held in contact with an inner peripheral wall (not shown) of the container 4.

[0006] In the basket 1 to which the assembly of the lattice by the fuel rack is applied, the rectangular cylinder 2 is connected to the fuel assembly 7 by one.
The fuel assembly 7 is stored in the A storage cell 8 in the rectangular cylinder 2 by having a size capable of accommodating each body and combining the rectangular cylinder 2 to a predetermined size using a spacer. I do. These fuel assemblies 7 are supported on the bottom plate of the recycled fuel transport storage container 4. The rectangular cylinder 2 is generally made of a boron-added aluminum alloy cylinder obtained by bending a plate material and welding the joint thereof, and has a bent portion 2a having a curvature at the corner.

Further, in the basket 1 of the recycled fuel transport storage container in which the rectangular cylinders 2 are combined in a staggered lattice, the diagonal dimension L is set to an appropriate length by setting the bent portion 2a to an appropriate size, and By adjusting the thickness of the flat bar 11, the thickness portions of the rectangular cylinder 2 can be made to overlap each other, and ultimately, the inner diameter of the A storage cell 8 and the inner diameter of the B storage cell 10. Thus, the basket 1 of the recycle fuel transport storage container having the same high density can be formed as in the case where the grid-like storage cells are assembled with one plate material.

However, in this method, since the rectangular cylinders are joined by welding, the basket itself has a rigid state as a single structure, and the structure is optimal for a fuel rack that requires self-support, but the temperature is low. In order to raise the basket of the recycle fuel transport storage container, it is necessary to consider the occurrence of thermal stress due to the difference in thermal expansion.

[0009]

In the conventional assembly of a basket for a recycle fuel transport storage container, since the rectangular cylinders 2 are supported by the spacing of the spacer rings, the spacing between the rectangular cylinders 2 is reduced. As a result, it was difficult to increase the number of storage containers for recycled fuel. Also,
As in the case of the fuel rack, the rectangular cylinders 2 are fixed to each other by welding 12 at the corners of the rectangular cylinder 2 via flat bars 11, but the rectangular cylinder 2 is made of a plate material as described above. And has a bent portion 2a having a curvature at a corner thereof.

The diagonal dimension L between the bent portions 2a is not always constant but has a large tolerance. For this reason, when assembling with the flat bar 11 interposed between the bent portions 2a on the diagonal line of the rectangular cylindrical body 2, in order to reduce the storage pitch, a square B storage cell 10 formed by the outer surfaces of the four rectangular cylindrical bodies 2 is used. Is the same as the inside diameter of the A storage cell 8 in the prismatic body 2, and
It is extremely difficult to accurately assemble the pitch between the storage cells to a value required to maintain the subcriticality of the fuel assembly 7.

Therefore, in order to accurately manufacture the pitch between the fuel storage cells within a certain range, there is a problem that many man-hours for assembling such as confirmation of accuracy are required, and the economic efficiency is poor. Further, it is a basket of a recycled fuel transport storage container for storing and storing a prismatic shaped recycled fuel assembly in a large number of cells formed in a lattice shape, wherein the cells are formed with a large number of slits, and a plurality of slits are formed. A second lattice plate having a cell width, and a first lattice plate having a width of one cell formed with a protrusion inserted into a slit of the second lattice plate, and the inserted portion is formed. In the method of assembling by finger welding, the density of packing is improved, but there is a problem that thermal stress due to thermal expansion is prevented from being relaxed.

It is an object of the present invention to combine and combine plate-like lattice plates provided with protrusions and slits to maintain good pitch accuracy between fuel storage cells and to reduce thermal stress at operating temperatures. Another object of the present invention is to provide a basket for a recycle fuel transport storage container which is easy to assemble and has an improved density, and a method for manufacturing the same.

[0013]

According to the present invention, there is provided a basket for a recycle fuel transport storage container for storing a prismatic recycle fuel assembly in a large number of cells formed in a lattice, and storing the recycle fuel assembly. Forming a plurality of slits in the cell, a second grid plate having a width of a plurality of cells,
A first lattice plate having a width corresponding to one cell and having a projection formed in a slit of the second lattice plate, and inserting and fixing the inserted portion, and assembling the assembly with bolts or the like And restrained by the frictional force of the fastening of the joint, thereby alleviating the generation of thermal stress due to thermal expansion.

That is, according to the first aspect of the present invention, there is provided a basket for a recycled fuel transport storage container for storing and storing a prismatic recycled fuel assembly in a large number of cells formed in a grid. A first lattice plate formed with a slit, a second lattice plate formed with a slit, an intersection at which the projection of the first lattice plate is inserted into the slit of the second lattice plate, and the four intersections. A plurality of grids formed in combination with each other, these grids are configured to be shorter than the facing distance of the inner peripheral wall of the container in which it is to be accommodated,
A fixed plate slidable along the length direction is combined with an end of the grid with a fixed fastening force, and the fixed plate is brought into contact with the inner peripheral wall of the container to fix the grid. A basket for recycle fuel transport storage containers is provided.

According to a second aspect of the present invention, in the basket for a recycled fuel transport storage container according to the first aspect, the lattice and the fixing plate are fastened by bolts inserted into at least one of the long holes formed in any of them. Provide a basket of recycled fuel storage containers.

According to a third aspect of the present invention, in the basket for a recycled fuel transport storage container according to the first aspect, the fixing plate has a U-shape fitted between a pair of opposed lattices constituting one cell. A basket for a recycled fuel transport storage container is provided which is a piece.

According to a fourth aspect of the present invention, there is provided a method for manufacturing a basket of a recycled fuel transport storage container for storing and storing a prismatic recycled fuel assembly in a large number of cells formed in a grid. A projection forming step of forming a projection on the first grid plate, a slit forming step of forming a slit on the second grid plate, and a projection formed in the projection forming step on the slit formed in the slit forming step. Inserting and forming an intersection, combining the four intersections formed in the intersection forming step to form a grid, fastening a slidable fixing plate to the end of these grids, and fixing the fixing plate. And fixing the lattice to the inner peripheral surface of the container to accommodate the grid through the method.

According to the present invention, a plurality of lattice plates provided with projections or slits in two plate shapes having predetermined dimensions are combined, and these are sequentially assembled to form a basket in which a plurality of cells are juxtaposed. Because of the configuration, the shape and assembly of the lattice plate can be easily and firmly formed.

Further, since high dimensional accuracy can be obtained, it is extremely easy to optimally set the pitch in consideration of the dimensions and subcriticality of the fuel assemblies contained in the basket, and include the fuel assemblies to be stored. The density can be improved.

Further, the generation of thermal stress in a high-temperature region can be reduced by fastening the lattice assembly using the frictional force of bolts.

[0021]

Embodiments of the present invention will be described below with reference to the drawings. The same components as those of the above-described conventional technology are denoted by the same reference numerals, and detailed description thereof will be omitted. As shown in the plan view of FIG. 1 and the partially cutaway side view taken along the line AA of FIG. 1, the basket 20 of the recycled fuel transport storage container has a plurality of first grid plates 21.
And the second grid plate 22 are combined in a grid shape, and fitted and fixed to each other to form a plurality of square-shaped fuel storage cells 23 arranged side by side. The basket 20 of the recycled fuel transport storage container is attached to the bottom plate of the recycled fuel transport storage container 1, and the plurality of fuel assemblies 7 are individually inserted into the fuel storage cells 23 and seated and supported on the bottom plate.

FIG. 3 is an enlarged vertical sectional view taken along line BB of FIG. 1, and FIG. 4 is a plan sectional view taken along line CC of FIG. FIG. 5 is a plan sectional view taken along line DD of FIG. As shown in these figures, the first lattice plate 21 has a length corresponding to the axial length of the fuel assembly 7 and the fuel storage cell 2.
3, a plurality of protrusions 24 are provided along one end surface thereof, and a protrusion of the adjacent first lattice plate 21 is provided on the end surface of the opposite example. Part 24
And a concave portion 25 that fits with the groove. On the other hand, the second lattice plate 22 has a length corresponding to the axial length of the fuel and a width corresponding to the width of the basket 20 of the recycled fuel transport storage container in which the plurality of fuel storage cells 23 are juxtaposed. A plurality of slits 26 into which the projections 24 of the first grid plate 21 are inserted at a pitch of one cell of the fuel storage cells 23.
Has been processed.

The plurality of first lattice plates 21 and second lattice plates 21
Are arranged so as to intersect at right angles to each other on the plane of the basket 20 of the recycled fuel transport storage container, and the projections 24 of the first lattice plate 21 are inserted into the slits 26 of the second lattice plate 22, Furthermore, after fitting the recess 25 of the other first lattice plate 21 adjacent to the projection 24 of the first lattice plate 21 protruding from the second lattice plate 22, the first lattice plates 21 and , The first lattice plate 21 and the second lattice plate 2
2 to form a plurality of side-by-side fuel storage cells 23.

FIG. 6 is a plan view showing a state in which the end of the lattice plate 22 of the basket is fixed to the recycled fuel transport container 4. Since the recycled fuel transport container 4 shown in FIG. 6 is a circular container, the inner peripheral surface serving as the support surface of the lattice plate 22 is curved in an arc.

As shown in FIG. 6, in this embodiment, the lattice plate 22 is configured to be shorter (for example, about 5 mm) than the facing distance of the inner peripheral wall of the recycled fuel transport container 4 in which the lattice plate 22 is to be accommodated, and the gap 31 Is formed. A fixed plate 30 slidable along the length direction is combined with an end portion of the grid plate 22 with a fixed fastening force, and the fixed plate 30 comes into contact with the inner peripheral wall of the recycled fuel transport container 4, thereby forming a grid. The plate 22 is configured to be fixed.

That is, an elongated hole 32 is formed in at least one of the grid plate 22 and the fixed plate 30, for example, the fixed plate 30, and the bolt 29 is inserted into the elongated hole 32.
It is fastened by a nut 33. The fixed plate 30 is, for example, a flat U-shaped piece-like member fitted between a pair of opposed lattice plates 22 forming one cell, and is fixed in the height direction of the lattice plate 22 (see FIG. 6). Plural pieces are arranged on the front and back sides of the paper. Since the illustrated fixing plate 30 is U-shaped, it can be closely assembled to the opposing lattice plate 22 and has an advantage that it can be stably fixed to the inner peripheral wall of the recycled fuel transport container 4. However, the shape of the fixing plate is not necessarily limited to the illustrated one, and various modifications or applications such as a mere plate-like shape or a tubular cross-sectional shape are possible.

According to such a configuration, by fastening the fixing plate 30 with the bolts 29 and the nuts 33, the stress due to the thermal expansion of the grid plate 22 is reduced by the slip between the fixed plate 30 and the grid plate 22. Can be. At the time of construction, a slidable fixing plate 30 is fastened to the end of the grid plate 22 with bolts 29 or the like, and the inner periphery of the recycled fuel transport container 4 in which the grid plate 22 is to be accommodated via the fixing plate 30. The step of fixing to the surface allows easy and reliable fixing.

Therefore, according to this structure, it is possible to sufficiently withstand use conditions such as transportation and storage, and to safely and reliably transport and store a large number of fuel assemblies 7. In order to reduce the pitch between the fuel storage cells 23 and make the basket of the recycle fuel transport storage container 4 denser, the plate members of the first grid plate 21 and the second grid plate 22 are both neutrons. It is desirable to employ a boron-added aluminum alloy that has excellent absorption capacity and is also effective as a strength member. However, if necessary, for example, the first lattice plate 21 or the second lattice plate 22 may be alternately provided, or a normal aluminum alloy may be partially used, or it may have excellent mechanical strength or neutron absorption ability. It is also possible to easily mix materials such as boron-added stainless steel as appropriate.

Next, an example of assembling the basket 20 of the recycled fuel transport storage container 4 will be described. First, as shown in the lattice plate assembly explanation perspective view of FIG. 7, in one second lattice plate 22, a plurality of first lattice plates 21 are arranged so that the concave portions 25 thereof face the positions of the slits 26. And the second grid plate 22 is fixed to the end surface of the welded first grid plate 21 by welding 27 to form one rack unit 28. Thereafter, a plurality of rack units 28 are manufactured in the same procedure.
Next, as shown in the enlarged perspective view of the main part of the rack unit in FIG. 8, the projection 24 of one rack unit 28 is inserted into the slit 26 of the other rack unit 28, and is projected from the slit 26 to form the first grid plate. After being fitted into the recess 25 of the first lattice plate 21, the projection 24 of the first lattice plate 21 and the second projection 22 protruding from the slit 26 of the second lattice plate 22 as shown in FIG.
After positioning the lattice plate 22 with a jig (not shown), welding 27 is performed. Projection 24 of first lattice plate 21
And the recess 25 of the other first lattice plate 21 are also fixed by welding 27 at the mating portion. Similarly, the basket 20 of the recycled fuel transport storage container is completed by sequentially connecting and assembling a plurality of basket units 28 in the same manner. As described above, the two types of plate-like lattice plates are
8 and the assembly of the fuel storage cell 23 by the basket unit 28 are both of a structure in which projections and slits are fitted. Therefore, not only insertion but also strong connection by welding and fastening with bolts can be achieved. . Further, it is not necessary to adjust the pitch between the fuel storage cells required due to the subcriticality of the stored fuel, and it is possible to set the pitch uniformly within a predetermined range with high accuracy. Further, since the protrusion member is not interposed in the fuel storage cell 23, the fuel assembly 7 can be easily inserted.

[0030]

As described above, according to the present invention, two kinds of lattice plates made of a plate material are assembled by fitting projections and slits thereof, and are further secured to the inner wall of the container by bolts or the like. Since it is firmly fixed, the dimensional accuracy of each part can be obtained with high accuracy, and it is possible to easily increase the pitch between fuel storage cells, which is required in terms of subcriticality of fuel, and to increase the density. In addition, it has a structure that alleviates thermal stress, has effects such as being easy to assemble and reducing the number of manufacturing steps.

[Brief description of the drawings]

FIG. 1 is a plan view of a basket of a recycled fuel transport storage container of the present invention.

FIG. 2 is a partially cut-away side view taken along the line AA of FIG. 1;

FIG. 3 is an enlarged vertical sectional view taken along line BB of FIG. 1;

FIG. 4 is a cross-sectional plan view taken along the line CC in FIG. 3;

FIG. 5 is a cross-sectional plan view taken along line DD of FIG. 3;

FIG. 6 is an enlarged plan view showing a fixed state of the basket to the container according to the embodiment of the present invention.

FIG. 7 is a perspective view illustrating a lattice plate assembly.

FIG. 8 is an enlarged perspective view of a main part of the basket unit.

FIG. 9 is a plan view of a basket of a conventional recycled fuel transport storage container.

FIG. 10 is a partially cut-away side view taken along the line EE in FIG. 9;

FIG. 11 is a partially enlarged plan view of FIG. 9;

FIG. 12 is an exploded view showing a spacer-type basket of a conventional recycled fuel transport storage container.

FIG. 13 is a schematic view showing an assembled state of FIG. 12;

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 basket 2 rectangular cylinder 3 spacer 4 recycled fuel transport storage container 7 fuel assembly 8 A storage cell 10 B storage cell 11 flat bar 12 welding 20 basket of recycled fuel transport storage container 21 first grid plate 22 second grid Plate 23 fuel storage cell 24 protrusion 25 recess 26 slit 27 welding 28 basket unit 29 bolt 30 fixing plate 31 gap 32 long hole 33 nut

Claims (4)

[Claims] 1. A basket of a recycled fuel transport storage container for storing a prismatic recycled fuel assembly in a large number of cells formed in a grid, the first grid having a projection. A plurality of plates formed by combining the plate, a second grid plate having slits, intersections for inserting the projections of the first grid plate into the slits of the second grid plate, and the four intersections. Having a grid, these grids being shorter than the facing distance of the inner peripheral wall of the container in which it is to be accommodated, and a fixed plate slidable along the length direction at the end of the grid. A basket for a recycle fuel transport storage container, wherein the basket is combined by a fixed fastening force and the grid is fixed by bringing the fixing plate into contact with the inner peripheral wall of the container. 2. The basket for a recycled fuel transport storage container according to claim 1, wherein the grid and the fixing plate are fastened by bolts inserted into at least one of the elongated holes formed in any of them. Storage container basket. 3. The basket for a recycled fuel transport storage container according to claim 1, wherein the fixing plate is a U-shaped piece that is fitted between a pair of opposed lattices forming one cell. , Recycle fuel transport storage container basket. 4. A method of manufacturing a basket of a recycled fuel transport storage container for storing and storing a prismatic shaped recycled fuel assembly in a large number of cells formed in a grid, comprising: A projection forming step of forming a projection,
A slit forming step of forming a slit in the second lattice plate, a step of inserting the protrusion formed in the protrusion forming step into the slit formed in the slit forming step to form an intersection, and a step of forming the intersection Combining the four intersections formed in the above into a grid, fastening a slidable fixing plate to the ends of these grids, and attaching the grid to the inner peripheral surface of the container to accommodate the grid via the fixing plate. Fixing the recycled fuel transport storage container basket.