JPH0862379A - Spent fuel storing rack, its manufacture, and device for manufacturing it - Google Patents

Abstract

PURPOSE: To provide a spent fuel storing rack with high quality and excellent economic property in which assembling precision, fuel storing density, and earthquake resistance are improved. CONSTITUTION: A flat lattice plate 31 having a slit and a band lattice plate 32 having a projection fitted to the slit are vertically and horizontally combined together to constitute the spent fuel storing rack 30. The flat lattice plate 31 and the band lattice plate 32 are fixed together by welding to form a one-line unit, and this unit is successively assembled to form the lattice spent fuel storing rack 30. In the assembling of this rack 30, the rack is held by a rotating device, and the lattice four corners are welded regularly downward by an automatic welding device. Thus, the fuel storing density is improved without having no wasteful space, the assembling precision is improved since the lattice is assembled every line, and the earthquake resistance is improved by the welding of the lattice four corners.

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 for accommodating and storing spent fuel assemblies taken out from a nuclear reactor in a fuel storage pool, a method for producing the same, and an apparatus for producing the same.

[0002]

2. Description of the Related Art Generally, in a nuclear power plant,
After the reactor has been in operation for a certain period of time, the spent fuel taken out of the core is stored and stored in a spent fuel storage rack that is installed in advance in the spent fuel pool until it is reprocessed. Removes decay heat of fuel.

In recent years, there has been a demand for effectively utilizing the space in the spent fuel pool to increase the storage capacity, and for this purpose, for example, a material having a large neutron absorption capacity is interposed between the stored fuels so that the fuels cannot be used together. Spent fuel storage that can increase the density by narrowing the space between stored fuels while maintaining criticality and by using this material as a strength member to support the stored fuel even during earthquakes, etc. A rack is proposed.

As a typical example of such a spent fuel storage rack, a boron-added stainless steel containing boron excellent in neutron absorption capacity and having good structural strength is used.
A so-called lattice plate-shaped fuel storage cell structure in which one piece of boron-added stainless steel is interposed between stored fuels is known.

There is a combination of pre-formed rectangular cylinders in a zigzag pattern because they satisfy such conditions and have good strength. That is, the plan view of FIG. 14 and the FIG.
As shown in a partially cutaway side view taken along the line F-F of FIG. 16 and a partially enlarged plan view of FIG. 16, a spent fuel storage rack 1 of this type has a large number of rectangular cylinders 2 arranged on a base 3. Is installed,
The base 3 on the bottom of the fuel storage pool 4 such as the reactor building
Are fixed by bolts 5 and nuts 6.

The square cylinder 2 has a size capable of accommodating the fuel assemblies 7 one by one, and the square cylinders 2 are combined in a staggered pattern as shown in FIG. Body 2
The fuel assembly 7 is stored in the first storage cell 8 in the inside, and the rectangular shape formed by the outer surface of the four rectangular cylinders 2 or the outer surface of the three rectangular cylinders 2 and one closing plate 9. The fuel assembly 7 can also be stored in the second storage cell 10 of the above.

These fuel assemblies 7 are fitted into and supported by the seating holes 3a on the base 3. The rectangular tube 2 is generally made of a rectangular tube made of boron-added stainless steel, which is formed by bending a plate material and welding the joints, and has a bent portion 2a having a curvature at the corner.

In assembling the rectangular tubular bodies 2 in a hound's-tooth check pattern, a flat bar 11 is sandwiched between diagonally bent portions 2a of the rectangular tubular bodies 2 adjacent to each other as shown in FIG. Via a welding 12 to form a spent fuel storage rack 1 in which a large number of storage cells 8 and 9 that are continuous in a grid pattern are formed.

In the spent fuel storage rack 1 in which the square tubular bodies 2 are combined in a staggered pattern, the square tubular body 2 is formed by adjusting the bent portion 2a to an appropriate radius and adjusting the thickness of the flat bar 11. It is possible to make the plate thickness portions of the two overlap.

Ultimately, the inner diameter of the first storage cell 8 and the inner diameter of the second storage cell 10 are the same, and a spent fuel storage rack similar to the one in which a grid-shaped storage cell is assembled with a single plate material. 1 can be formed.

In manufacturing the spent fuel storage rack 1 described above, the rectangular cylinders 2 are sequentially arranged at predetermined positions at intervals of 10 minutes for the second storage cells, and the second storage cells 10 are preliminarily arranged. The closing plate 9 disposed at the position is welded and connected to assemble the first stage.

After that, the rectangular tubular bodies 2 are respectively arranged directly above the B storage cells 10 assembled in the first stage, and the rectangular tubular bodies 2 assembled in the first stage are arranged.
Insert the flat bar 11 between the bent part 2a and the
The rectangular tubular bodies 2 are connected to each other by assembling, and the second stage assembly is performed. After that, the rectangular tubular bodies 2 are sequentially stacked in the same procedure to manufacture the spent fuel storage rack 1.

In this case, a crane is used to convey the square tubular body 2 or the like, and after the square tubular body 2 is set on a positioning jig by hand by an operator in order to position the square tubular body 2 at a predetermined position. The space between the bent portions 2a of the rectangular tubular body 2 is measured, and a flat bar 11 having a thickness corresponding to the measured portion is selected and sandwiched, and temporary welding and main welding are performed by manual welding.

However, since the rectangular tubular body 2 is formed by bending a plate material, the diagonal dimension L between the bent portions 2a is not always constant and has a large tolerance, so that the pitch between the storage cells can be accurately assembled. Therefore, it is difficult to improve the density.

As means for solving this problem, for example, Japanese Patent Laid-Open No.
The technique disclosed in Japanese Patent Publication No. 5-80188 is known. That is, as shown in the plan view of FIG. 17, the spent fuel storage rack 20 is composed of a plurality of first grid plates 21 and second grid plates 22 combined in a grid pattern, and fitted and fixed to each other to form a plurality of square plates. The fuel storage cells 23 arranged in parallel are formed.

This spent fuel storage rack 20 has bolts and nuts (not shown) on the bottom of a fuel storage pool (not shown).
The plurality of fuel assemblies 7 are individually inserted into the fuel storage cells 23 and fitted and supported in the seating holes (not shown) on the base 3 by being mounted on the base 3 fixed by.

Further, an enlarged vertical sectional view taken along the line GG of FIG. 17 in FIG. 18, a sectional view taken along the line HH of FIG. 18 in FIG. 19 and I of FIG. 18 are shown. 21 is a sectional view taken along line I and FIG.
As shown in the perspective view of FIG. 1, the first lattice plate 21 has a length corresponding to the axial length of the fuel assembly 7 and a width corresponding to the width of one cell of the fuel storage cell 23, and extends along one end surface thereof. Is provided with a plurality of protrusions 24, and the opposite end face is provided with a recess 25 that fits with the protrusion 24 of the adjacent first lattice plate 21.
Are formed.

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 spent fuel storage rack 20 in which a plurality of fuel storage cells 23 are arranged in parallel. Cage,
A plurality of slits 26 into which the protrusions 24 of the first lattice plate 21 are inserted are formed at a pitch of one cell of the fuel storage cells 23.

The plurality of first grid plates 21 and second grid plates 22 are arranged so as to intersect each other at a right angle on the plane of the spent fuel storage rack 20, and the slits 26 of the second grid plate 22 are arranged.
The protrusion 24 of the first lattice plate 21 is inserted into the above, and the recess 25 of another first lattice plate 21 adjacent to the protrusion 24 of the first lattice plate 21 protruding from the second lattice plate 22 is fitted. After putting them on, the first grid plate 21 and the first grid plate 21 and the second grid plate 21
Welding 27 of 22 together results in a strong bond to each other to form a plurality of juxtaposed fuel storage cells 23.

In the production of this spent fuel storage rack 20, the slit 26 is formed in one second lattice plate 22.
A plurality of first grid plates 21 are arranged at right angles with the concave portions 25 thereof facing each other, and the contacting end surface of the first grid plate 21 and the second grid plate 22 are It is fixed by welding 27 and the first stage is assembled.

Next, the protrusions of the first grid plate 21 of the first stage
The second lattice plate 22 is placed so that the slits 26 of the second lattice plate 22 of the second stage come on the plate 24, and the projections 24 of the first lattice plate 21 are placed on the second lattice plate 22 of the second stage. It is inserted into the slit 26 and the protrusion 24 is projected from the slit 26.

After that, the first grid plate 21 of the second step is arranged so that the recess 25 thereof fits with the projection 24 protruding from the slit 26, and the first grid plate of the first step is welded 27. The protrusion 24 of 21 is connected to the second grid plate 22 of the second stage and the first grid plate 21 of the second stage. Thereafter, in the same procedure, the second grid plate 22 and the first grid plate 21 are sequentially stacked to manufacture the spent fuel storage rack 20.

In this case, a crane is used to convey the second grid plate 22 and the first grid plate 21, and the positioning of each grid plate and the insertion of the protrusions 24 and the slits 26 are done by a worker. Relying on work, temporary welding and main welding are also manual welding.

As described above, since the pitch between the storage cells is determined by the machining method, it is possible to manufacture a spent fuel storage rack which is easy to assemble, has high accuracy, and has improved density.

[0025]

When assembling a conventional spent fuel storage rack in which pre-formed square tubular bodies are combined in a staggered pattern, a flat bar 11 is provided at a corner of the square tubular body 2.
The square tubular bodies 2 are fixed to each other by welding 12 via the, but the square tubular body 2 is made by bending the plate material as described above.

A bent portion 2a having a curvature is provided at the corner, and the diagonal dimension L of the bent portion 2a is not always constant but has a large tolerance. Therefore, when the flat bar 11 is sandwiched between the bent portions 2a on the diagonal line of the rectangular tubular body 2 to assemble, the four rectangular tubular bodies 2 are arranged in order to reduce the storage pitch.
The inner diameter of the rectangular second storage cell 10 formed on the outer side surface of the fuel cell 7 is made equal to the inner diameter of the first storage cell 8 in the rectangular tube body 2, and the subcriticality of the fuel assembly 7 is maintained.

Therefore, it is extremely difficult to assemble the pitches between the storage cells to the required values with high accuracy, and it is necessary to accurately assemble the pitches between the fuel storage cells within a certain range. There is a problem that it takes a lot of man-hours for assembling due to confirmation and the economy is poor.

Japanese Unexamined Patent Application Publication No.
In Japanese Patent Laid-Open No. 5-80188, the combination of the flat second grid plate 22 and the plurality of strip-shaped first grid plates 21 is the first grid plate 21 protruding from the slit 26 of the second grid plate 22. Since it is limited to the protrusion 24 of, only a fraction of the total height of the lattice plate can be fixed,
There is a problem that the rigidity of the connection between the lattice plates is weak and the earthquake resistance is poor.

In addition, machining the protrusions 24 and the recesses 25 of the first grid plate 21 and the slits 26 of the second grid plate 22 to a fraction of the total height requires a small number of processing steps. There is also the drawback of increasing.

As a similar example, for example, Japanese Patent Laid-Open No. 5-8
[0189] The technology disclosed in Japanese Patent Laid-Open No. 5189188 is known, and a combination of a flat lattice plate and a strip lattice plate is formed in a slit formed in the flat lattice plate, and a protrusion of the strip lattice plate is disclosed in JP-A-5-80188. After inserting in the same manner as above, it is supposed to be done by plug welding. Also in this case, for the same reason as in Japanese Patent Laid-Open No. 5-80188, there is a problem that the seismic resistance is poor and the number of processes increases.

On the other hand, in manufacturing the spent fuel storage racks of the above two types, a worker sequentially operates a rectangular cylinder or a lattice plate.
The process of stacking them step by step and performing temporary fixing and main welding is performed.For the transportation of the rectangular cylinders or lattice plates, a crane is used, and a method of manually setting them on the positioning jig is adopted. The welding was also manual welding by workers. For this reason, the number of assembling steps is increased, the manufacturing period is long, and there is a problem that the manufacturing must be dependent on the skill of the worker.

The present invention has been made in order to solve the above-mentioned problems, and a plurality of grid plates are accurately combined to improve the density, and the intersections of the grid plates are required from the inside of the storage cell in terms of strength. Spent fuel storage rack with excellent seismic resistance by welding a large amount of it, and high quality, and an inexpensive spent fuel storage rack, and the method of manufacturing the storage rack, and automation, with stable quality without spent workers, spent fuel An object of the present invention is to provide a manufacturing apparatus capable of assembling a storage rack.

[0033]

In the spent fuel storage rack of the present invention, a fuel storage cell formed by combining lattice plates is a plate material having substantially the same width as the width of one fuel assembly and is provided on both end surfaces. A strip-shaped lattice plate provided with a plurality of protrusions, and a plurality of plate members whose width is approximately the same as a multiple of the width of the fuel assembly, and the protrusions of the strip-shaped lattice plate are inserted at substantially the same intervals as the width of the fuel assembly. It is composed of a flat lattice plate with slits processed, the projections of the strip lattice plate are inserted into the slits of the flat lattice plate to assemble, and then the four corners are fixed by welding from the inner surface of the storage cell with a welding torch that can be inserted into the storage cell. It is characterized by being done.

Further, in the method for manufacturing a spent fuel storage rack according to the present invention, the corners of the lattice plate constituting the storage cell are positioned so as to face downward, and the welding torch inserted in the storage cell is used for stable operation. The welding is performed downward to firmly fix the intersection of the lattice plates, and the rollers in front of and behind the welding torch are placed in the V-shaped groove of the storage cell facing downward, and the rollers are moved in the longitudinal axis direction of the storage cell to guide welding. It is characterized by performing.

Further, in the method for manufacturing a spent fuel storage rack of the present invention, a temporary assembly of storage cells is mounted, and the storage cells are rotated about their longitudinal axes so that the V-shaped groove of each storage cell faces downward. A mechanism that has a rotating device that can be positioned and an arm that is connected to the rear end of the welding torch and that can move the welding torch at a predetermined speed in the horizontal longitudinal axis direction of the storage cell; The present invention is characterized in that it is provided with a mechanism that is driven in a direction to detect a storage cell corner and automatically positions the welding torch, and a mechanism device that automatically controls these.

[0036]

The present invention includes two types of grid plates whose dimensions are predetermined,
A storage rack is configured by combining a plurality of pieces provided with protrusions and slits. Therefore, the dimensional accuracy is increased depending on the machining, and the denseness is improved. In addition, since the four corners are fixed by welding from the inside of the storage cell by the automatic welding device that can be inserted into the storage cell, the entire lattice plate is rigidly connected and consequently the earthquake resistance is improved.

Further, by welding the intersections of the grid plates at the corners of the storage cells downward, the reliability of the welded parts is improved. At the same time, since the welding torch can be moved using the V-shaped groove at the intersection of the lattice plates as a guide, positioning of the welding torch with respect to the welding line is facilitated and automation is facilitated.

The spent fuel storage rack after temporary assembly is rotated around the longitudinal axis to assemble the rack by using a manufacturing apparatus equipped with a mechanism for moving and positioning the welding torch and a mechanism for controlling these. As a result, a high quality rack can be manufactured without depending on the skill level of the worker.

Due to the above-mentioned respective constitutional requirements and actions, the spent fuel storage rack having improved dimensional accuracy and improved denseness and increased rigidity and improved earthquake resistance can be easily and shortly manufactured by highly reliable automatic welding. It can be manufactured on time and without depending on the skill of the worker.

[0040]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to the drawings. It should be noted that the same components as those of the above-described conventional technique 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 enlarged vertical sectional view taken along the line AA of FIG. 1 in FIG. 2, the spent fuel storage rack 30 includes a plurality of flat grid plates, grid plates 31, and band grids. The plates (32) are combined in a lattice shape and fitted and fixed to each other to form a plurality of rectangular fuel storage cells (33) arranged side by side.

The spent fuel storage rack 30 is mounted on a base 3 which is fixed to the bottom of a fuel storage pool (not shown) by bolts and nuts (not shown). It is individually inserted into the storage cell 33 and fitted and supported in a seating hole (not shown) on the base 3.

Further, as shown in the sectional view taken along the line BB of FIG. 3 of FIG. 3, the sectional view taken along the line C-C of FIG. 4 of FIG. 4 and the perspective view of the lattice plate combination of FIG. The strip-shaped grid plate 32 has a length corresponding to the axial length of the fuel assembly 7 and the fuel storage cell 33.
A plurality of protrusions 35 are provided along both end surfaces of the protrusion 35 with a width corresponding to the width of one cell, and the protrusion 35 has an installation height on one end face and an installation height on the opposite end face. , Are formed at different positions.

On the other hand, the flat lattice plate 31 has a length corresponding to the axial length of the fuel assembly 7 and a width corresponding to the width of the spent fuel storage rack 30 in which a plurality of fuel storage cells 33 are arranged side by side. Therefore, a plurality of slits 34 into which the protrusions 35 of the strip-shaped grid plate 32 are inserted are processed at a pitch of one cell of the fuel storage cells 33. The height of the protrusions 35 of the strip-shaped grid plate 32 is set to be slightly smaller than the thickness of the flat grid plate 31.

The plurality of flat lattice plates 31 and strip lattice plates 32 are arranged in the slits 34 of the flat lattice plate 31 so as to intersect each other on the plane of the spent fuel storage rack 30 at right angles.
After inserting the protrusions 35 of the strip-shaped grid plate 32,
31 and the band-shaped grid plate 32 are firmly connected to each other by welding 36.

As a result, a plurality of fuel storage cells arranged in parallel are provided.
33 is formed, in which case the welding 36 is performed from within the storage cell 33 and to its four corners. In forming the fuel storage cell 33, since the projections 35 of the strip-shaped lattice plate 32 are located at different heights on both end faces, the flat lattice plate is formed.
It is possible to dispose band-shaped lattice plates 32 on both sides of 31 and insert the projections 35 thereof into the slits 34 of the plate-shaped lattice plate 31 having different heights without interfering with each other.

Further, since the height of the projections 35 of the band-shaped grid plate 32 is set to be slightly smaller than the thickness of the flat grid plate 31, the projections 35 are inserted into the slits 34 of the flat grid plate 31. In this case, the end face of the next strip-shaped lattice plate 32, which does not protrude from the surface on the opposite side of the flat lattice plate 31, but comes to this face, can be brought into close contact with the surface of the flat lattice plate 31.

According to this structure, the pitch between the fuel storage cells can be accurately assembled to improve the denseness, and the lattice plates can be firmly joined to each other in a cruciform joint by welding.
It can sufficiently withstand vibrations during an earthquake and can accommodate a large number of fuel assemblies 7 and store them safely and reliably.

The welding 36 may be carried out continuously over the entire length of the flat lattice plate 31 and the strip lattice plate 32 in the longitudinal direction, or when the load on the weld 36 is small because the demand for seismic resistance is not strict. It may be intermittent welding. In this case, the number of man-hours required for welding can be reduced and the work period can be expected to be shortened.

Further, since the projections 35 of the strip-shaped grid plate 32 do not participate in the welding connection between the grid plates, they are merely inserted into the slits 34 of the flat grid plate 31 for positioning each other. It is sufficient that the slit 34 and the protrusion 35 have several places over the entire height, and in this respect as well, the number of machining steps can be reduced and the manufacturing process can be expected to be shortened.

As another embodiment, as shown in the perspective view of FIG. 6, a pin 40 may be provided on the third band-shaped grid plate 39 and a hole 41 may be provided on the flat plate-shaped grid plate 31 instead of the slits and protrusions. good. In this case, the pin 40 does not necessarily have to be machined integrally from the third strip lattice plate 39, and can be attached by a suitable means such as welding.

Therefore, as compared with the strip-shaped grid plate 32 (see FIG. 5) in which the protrusions 35 are integrally machined, the number of working steps can be reduced,
Furthermore, the material can be saved. In addition, the flat lattice plate 31 has holes.
41 can also be processed by drilling and slit 34 shown in FIG.
Can reduce the processing man-hours.

On the other hand, the protrusions of the band-shaped lattice plate do not necessarily have to be installed at different heights on both end faces. For example, as shown in FIG. 7, the protrusions 35 of the first strip-shaped lattice plate 37 located on the left side of the flat lattice plate 31 are upwards, and the protrusions 35 of the second strip-shaped lattice plate 38 located on the right side are the first protrusions. The height may be different from that of the protrusions 35 of the strip-shaped grid plate 37, and they may be located at the same level in the same grid plate.

Further, if the height of the protrusions 35 is set to be slightly smaller than 1/2 of the thickness of the flat lattice plate 31, the height of the protrusions 35 is changed for each strip lattice plate as shown in FIG. There is no need, and they can be inserted into the same slit 34 of the flat lattice plate 31 without interfering with each other. In this case, the number of slits 34 of the flat grid plate 31 can be reduced by half, and the time required for processing can be further shortened.

Next, an embodiment of the manufacturing method and manufacturing apparatus for the spent fuel storage rack 30 will be described. First, as shown in the perspective view of the lattice plate combination of FIG. 5, the projections 35 of the strip lattice plate 32 are inserted into the slits 34 of the flat lattice plate 31, and the fuel storage cells 33 are sequentially formed. As shown in the plan view of FIG. 1, a grid plate temporary assembly 42 of 9 rows × 9 columns is manufactured.

FIG. 8 is a detailed view of the welding torch portion, and FIG. 9 is FIG.
DD line view of FIG. 10, FIG. 10 is an overall view of the manufacturing apparatus, and FIG.
11 is a view taken along the line EE of FIG. 10, and thereafter FIGS.
The main welding will be performed by each device shown in.

That is, in FIGS. 8 and 9, the welding torch 50 has rollers 51 supporting its own weight in the front and rear thereof, and a drive arm 52 for horizontally driving the welding torch 50 projects from the rear end thereof. Flat grid plate of the fuel storage cell 33
The V-shaped groove formed by 31 and the strip lattice plate 32 allows the roller
The roller 51 and the welding torch 50 are set so that the welding torch 50 is guided through the 51 and accurately set at a predetermined position.
Is freely movable in the vertical and horizontal directions with respect to the drive arm 52.

The rotating device 54 has a structure which holds the temporary grid plate assembly 42 and can rotate the temporary grid plate assembly 42 about its longitudinal axis. The controller 55 controls the temporary grid plate assembly 42 in a predetermined direction and angle. 42 can be positioned.

Further, the welding torch moving mechanism 53 includes a drive arm 52.
A mechanism for moving the welding torch 50 horizontally and vertically via the to position the fuel torch 50 in a predetermined fuel storage cell 33, and then driving the drive arm 52 to insert the welding torch 50 into the fuel storage cell 33 and perform welding. These operations are also controlled by the controller 55.

The rotating device 54 and the welding torch moving mechanism 53.
Are controlled by one controller 55 and operate in coordination with each other. Upon assembly, the temporary grid plate assembly 42 is set on a rotating device 54 that holds the temporary grid plate assembly 42 and can rotate about the longitudinal axis of the temporary grid plate assembly 42.

The rotating device 54 inclines the temporary grid plate assembly 42 from the horizontal by 45 ° so that the corners of the fuel storage cell 33 formed by the flat grid plate 31 and the band grid plate 32 are aligned as shown in FIG. After facing downward, the welding torch 50 is inserted into the fuel storage cell 33 and welding 36 is performed.

In this case, the welding torch 50 has its own weight supported by the rollers 51 attached to the front and rear thereof, and is horizontally driven by the drive arm 52 protruding from the rear end thereof. Also,
When hitting the welding 36 at the inner corner of the storage cell 33, the flat grid plate 31
Then, the V-shaped groove formed by the strip lattice plate 32 serves as a guide for the roller 51, and the welding torch 50 can be accurately positioned with respect to a predetermined welding portion.

Next, a series of working steps will be explained. First, the temporary grid plate assembly 42 is set on the rotating device 54, and the rotating device 54 is rotated in a predetermined direction and angle by the controller 55 to temporarily install the temporary grid plate assembly. After positioning the body 42 at a predetermined position, the welding torch moving mechanism 53 moves the welding torch 50 horizontally and vertically to position it at a predetermined fuel storage cell 33 of the temporary grid plate assembly 42, and inserts it by the drive arm 52. Then, the welding 34 is performed by the welding torch 50.

This series of welding torch moving mechanism 53, drive arm
The movement of 52 and the welding by the welding torch 50 are also controlled by the control device 55 and are performed in a series of operations as a predetermined procedure, and the necessary welding 36 is sequentially completed by a predetermined procedure. Thereafter, as shown in FIG. 1, the base 3 is attached to the lattice plate temporary assembly 42 on which all necessary welding 36 has been completed, and the assembly of the spent fuel storage rack 30 is completed.

As described above, since the welding torch 50 is automatically positioned by the rotating device 54, the welding torch moving mechanism 53 and the control device 55, and the welding operation can be performed, it is possible to obtain high quality without depending on the skill of the worker. It is possible to manufacture a rack, and it can be expected that the manufacturing period can be shortened by automation. Furthermore, stable downward welding at the grid plate intersection can provide a highly reliable product.

As another embodiment, first, as shown in FIG. 12, the projections 35 of a plurality of strip-shaped grid plates 32 are inserted into the slits 34 of one flat-plate grid plate 31, and the flat grid plate 31 and After the strip-shaped grid plates 32 are arranged at right angles, welding is performed from both sides of each strip-shaped grid plate 32 to manufacture the single-row unit 43.

The welding 36 has welding torches on both sides of the strip-shaped lattice plate 32, and can be moved in the entire length direction of the strip-shaped lattice plate 32, which is usually used as an automatic welding device (not shown). By using, the single-row unit 43 with stable quality can be manufactured in a short period of time.

After that, as shown in FIG. 13, a single row unit 43 is placed on the flat lattice plate 31 so that the end face of the strip lattice plate 32 is on the lower side, and the projections 35 are formed on the flat lattice plate 31. Board 31
Insert it into the slit 34 and make temporary assembly.

Thereafter, the one-row units 43 are successively stacked to assemble the lattice plate temporary assembly 42 of a predetermined size. After the grid plate temporary assembly 42 is assembled, the grid plate temporary assembly 42 is mounted on the rotating device 54 as described above, and the welding of the portion where welding is not performed is automatically performed.

According to such an assembling method, when the plurality of spent fuel storage racks 30 are manufactured, the assembly of the temporary grid plate assembly 42 and the assembly work of the single row unit 43 can be performed in parallel. It can contribute to shortening the construction period.

[0070]

According to the present invention, a spent fuel storage rack is assembled by precisely machining in advance and combining a plurality of two types of grid plates provided with projections and slits for assembly.
Therefore, the storage pitch can be reduced to improve the density, and if the intersections of the grid plates at the four corners are required from the inside of the fuel storage cell, welding can be performed over the entire length of the grid plate in the longitudinal direction. It is possible to provide a spent fuel storage rack having excellent properties.

Further, the rotating device for rotating the temporary assembly of the lattice plate, the moving mechanism of the welding torch, its control device, and the welding torch which can be inserted into the fuel storage cell automate the production of the spent fuel storage rack, and work High quality racks can be manufactured in a short period of time without depending on the skill level of personnel.

[Brief description of drawings]

FIG. 1 is a plan view showing an embodiment of a spent fuel storage rack according to the present invention.

FIG. 2 is an enlarged cross-sectional view taken along the line AA of FIG.

3 is a cross-sectional view taken along the line BB of FIG.

4 is a cross-sectional view taken along the line CC of FIG.

5 is a perspective view showing a lattice plate combination in FIG. 1. FIG.

FIG. 6 is a perspective view showing a lattice plate combination according to another embodiment of the present invention.

FIG. 7 is a perspective view showing a lattice plate combination according to another embodiment of FIG.

FIG. 8 is a schematic view showing a welding device used in the present invention.

9 is a front view in the direction of the arrow along the line D-D in FIG.

FIG. 10 is a configuration diagram showing a manufacturing apparatus of the present invention.

11 is a front view of the rotating mechanism in FIG. 10 taken along the line EE.

FIG. 12 is a front view showing a single-row unit in another manufacturing embodiment of the present invention.

FIG. 13 is an assembly diagram for explaining the manufacturing example in FIG. 12;

FIG. 14 is a plan view showing a conventional spent fuel storage rack.

FIG. 15 is a side view showing a part of the arrow direction along line FF in FIG.

16 is a plan view showing an enlarged main part in FIG.

FIG. 17 is a plan view showing another example of a conventional spent fuel storage rack.

FIG. 18 is an enlarged vertical sectional view taken along the line GG in FIG.

FIG. 19 is a cross-sectional view taken along the line HH of FIG.

20 is a cross-sectional view taken along line I-I of FIG.

21 is a perspective view for explaining the method of assembling the lattice plate in FIG.

[Explanation of symbols]

30 ... Spent fuel storage rack, 31 ... Flat lattice plate, 32 ... Strip lattice plate, 33 ... Fuel storage cell, 34 ... Slit, 35 ... Projection, 36 ... Welding, 37 ... First strip lattice plate a, 38 ... second strip lattice plate, 39 ... third strip lattice plate, 40 ... pin, 41 ... hole,
42 ... Lattice plate temporary assembly, 43 ... Single row unit, 50 ... Welding torch, 51 ... Roller, 52 ... Drive arm, 53 ... Welding torch moving mechanism, 54 ... Rotating device, 55 ... Control device.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toshiro Kodama 2-4 Suehirocho, Tsurumi-ku, Yokohama-shi, Kanagawa Toshiba Keihin Office

Claims (8)

[Claims] 1. A used fuel storage rack comprising a plurality of fuel storage cells for accommodating fuel assemblies one by one and installed on a base, wherein the fuel storage cells include a flat lattice plate and a strip lattice plate. A spent fuel storage rack, which is vertically and horizontally combined and in which the four corners of the inner surface of the fuel storage cell are fixed by welding. 2. The strip-shaped lattice plate is a plate material having a width substantially the same as the width of one fuel assembly, and a plurality of protrusions are provided on both end surfaces thereof, and the flat lattice plate has a width which is equal to the width of the fuel assembly. A plurality of slits into which the protrusions of the strip-shaped lattice plate are inserted are provided at the same intervals as the width of the fuel assembly in a plate member having a width substantially the same as the multiple, and the protrusions of the strip-shaped lattice plate are formed in the slits of the flat lattice plate. The spent fuel storage rack according to claim 1, wherein the rack is used and is assembled and welded. 3. The spent fuel storage rack according to claim 1, wherein the protrusions of the strip lattice plate are pins and the slits of the flat lattice plate are holes. 4. A method for manufacturing a spent fuel storage rack, comprising a fuel storage cell for accommodating a fuel assembly one by one, and a plurality of lattice plates are vertically and horizontally combined to be installed on a base. A method for manufacturing a spent fuel storage rack, characterized in that a welding torch is inserted in the fuel cell, and the intersections of the two grid plates are joined by welding from the inside of the fuel storage cell. 5. The grid plate constituting the fuel storage cell is positioned such that its corners face downward, and stable downward welding is performed by a welding torch inserted in the storage cell to fix the grid plate intersection. The method of manufacturing a spent fuel storage rack according to claim 4, wherein the spent fuel storage rack is manufactured. 6. A method for manufacturing a spent fuel storage rack, characterized in that one flat lattice plate and a plurality of strip lattice plates are combined in advance by welding to produce a unit, and then the units are stacked in a plurality of stages. . 7. A spent fuel storage rack manufacturing apparatus comprising a combination of a plurality of fuel storage cell lattice plates for accommodating one fuel assembly at a time, and a welding device having a size capable of being inserted into the fuel storage cell. It has a roller in front of and behind the torch, and has a structure in which the welding torch can be moved in the horizontal axis direction by an arm protruding at the rear end, and the roller is configured to move on the cell grid plate using the cell grid plate as a guide. An apparatus for manufacturing a spent fuel storage rack, which is characterized in that 8. A rotating device for rotating a temporarily assembled cell grid plate about its longitudinal axis, and a welding device for automatically positioning and inserting the welding torch into each of the cell grid plates for welding. 8. The apparatus for manufacturing a spent fuel storage rack according to claim 7, further comprising a control device for integrally controlling the welding device.