JP3505317B2 - Spent fuel storage rack and method of manufacturing the same - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spent fuel storage rack for accommodating and storing spent fuel assemblies taken out from a nuclear reactor in a fuel pool, and a manufacturing method thereof.

[0002]

2. Description of the Related Art Generally, in a nuclear power plant,
The spent fuel taken out of the core after operating the reactor for a certain period is stored and stored in a spent fuel storage rack that is installed in the fuel pool in advance until it is reprocessed. The heat of decay of the fuel is removed.

In recent years, there has been a demand for effectively utilizing the space in the fuel pool to increase the storage capacity. In order to meet this demand, a material having a large neutron absorption capacity is interposed between the stored fuels so that the fuel can be stored in the fuel pool. Proposed a spent fuel storage rack that can increase the packing density by narrowing the interval between stored fuels while maintaining subcriticality and by using this intervening member also as a strength member for supporting stored fuel during an earthquake etc. Has been done. As such a spent fuel storage rack, boron-added stainless steel, which has excellent neutron absorption capacity and good structural strength, is used between storage fuels.
There is known a so-called lattice plate-shaped fuel storage cell structure in which one by one is interposed.

That is, for example, in Japanese Laid-Open Patent Publication No. 5-80188, as shown in FIG.
(Referred to as a first lattice plate) and a plurality of lattice plates 2 orthogonal to the first lattice plate 2
2 (hereinafter referred to as the second grid plate) is combined in a grid pattern,
By fitting and fixing each other, a plurality of rectangular fuel storage cells 23 arranged in parallel are formed, and these are integrally mounted on the base 3 fixed to the bottom surface of the fuel pool by bolts and nuts (not shown). A spent fuel storage rack 20 is shown. The plurality of fuel assemblies 7 are
It is individually inserted into the fuel storage cell 23 and fitted and supported in a seating hole (not shown) on the base 3. Further, in this example, as shown in FIGS.
1 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 a plurality of protrusions 24 are provided along one end surface thereof. Cage,
In addition, a concave portion 25 that fits with the protruding portion 24 of the adjacent first lattice plate 21 is formed on the opposite end surface. On the other hand, the second lattice plate 22 has a length corresponding to the axial length of the fuel assembly 7 and a width corresponding to the entire width of the spent fuel storage rack 20 in which a plurality of fuel storage cells 23 are arranged side by side. A plurality of slits 26, into which the protrusions 24 of the first lattice plate 21 are inserted, are processed for each pitch of the cells 23. These first grid plate 21 and second grid plate 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 protrusions 24 of the first grid plate 21 are inserted into the slits 26 of the second grid plate 22. The first grid plate 2 protruding from the plate 22
The concave portion 25 of the first lattice plate 21 adjacent to the first protrusion 24.
And then the first grid plate 21 and the first grid plate 21 and the second grid plate 22 are welded 27 so that they are firmly fixed to each other, and a plurality of fuel storage cells 23 are arranged in parallel.
Is formed.

In manufacturing the spent fuel storage rack 20 as described above, first, in the second grid plate 22 of the first stage, a plurality of first grid plates 21 are formed in the recesses 25 at the positions of the slits 26. The side end faces of the first lattice plate 21 and the second lattice plate 22 which are arranged at right angles so as to face each other and are in contact with each other.
And are fixed by welding 27 and the first stage is assembled. Next, 2 is placed on the protrusion 24 of the first grid plate 21 of the first stage.
Second so that the slit 26 of the second grid plate 22 of the stage comes
The grid plate 22 is placed, the projections 24 of the first grid plate 21 are inserted into the slits 26 of the second grid plate 22 of the second stage, and the projections 24 are projected from the slits 26. After that, the second grid plate 21 of the second stage is arranged so that the concave portion 25 thereof fits with the protruding portion 24 protruding from the slit 26, and the welding 27
Thus, the protrusion 24 of the first grid plate 21 of the first stage 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 in the next stage are sequentially stacked and welded to assemble the spent fuel storage rack 20.

[0006]

As described above, in the conventional spent fuel storage rack, the first grid plate 2 has a structure.
The projection 24 of No. 1 must be projected from the slit 26 of the second grid plate 22 and joined by welding 27. For this reason, it is necessary to provide the second lattice plate 22 with the rectangular slits 26 at a pitch of one cell of the fuel storage cells 23 so that the cumulative total is about a fraction of the total height. It is necessary to provide the same number of protrusions 24 to be inserted into the slits 26 on the first grid plate 21 to be arranged, and it takes a lot of man-hours and time to machine these. Further, even when assembling, it is necessary to insert the projections 24 of the plurality of first lattice plates 21 into the large number of slits 26 of the second lattice plate 22 at the same time, so that the work is complicated and the assembling time also increases. . Therefore, there are problems that the manufacturing period of the spent fuel storage rack becomes long and the economical efficiency is poor.

The present invention has been made to solve the above-mentioned problems, and enables reduction of machining time and adjustment time at the time of assembly, resulting in a short manufacturing period and excellent economical efficiency. It is an object to provide a fuel storage rack.

[0008]

The spent fuel storage rack according to the present invention is a spent fuel storage rack in which partition plates are combined in a grid pattern, and a flat plate-like partition plate having a plurality of holes and the flat plate-like partition plate. The main feature is that the side end surfaces of the strip-shaped partition plates arranged at right angles to the partition plate are combined in a grid pattern so as to abut the hole positions of the flat plate-shaped partition plate, and the intersections thereof are integrated. . Further, the method for manufacturing a spent fuel storage rack of the present invention, a plurality of strip-shaped partition plates are vertically attached by welding in advance to the flat plate-shaped partition plate, and a hole of another flat plate-shaped partition plate is provided at the other end of the strip-shaped partition plate. After combining to match,
Integrating the intersections of these strip-shaped partition plates and flat plate-shaped partition plates,
Hereinafter, the method is characterized in that a spent fuel storage rack is manufactured by repeating this procedure.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, a pin having a shaft having a diameter insertable into a hole of a flat partition plate and a head having a diameter larger than this hole is inserted into the hole of the flat partition plate, The intersection point can be integrated by pressing the side end surface of the strip-shaped partition plate and stud welding. In this case, the hole of the flat partition plate is set to be smaller than the thickness of the strip partition plate, and one end thereof is provided with a spot facing, and the height of the pin head is smaller than the depth of the spot facing. It is desirable to set as follows.

[0010]

[0011]

[0012]

Embodiments of the present invention will be described below with reference to the drawings. The same components as those of the above-described conventional technique are designated by the same reference numerals, and detailed description thereof will be omitted unless necessary.

As shown in FIG. 1, the spent fuel storage rack 30 of the present invention has a plurality of flat plate-like partition plates 31 and strip-like partition plates 32 combined in a grid pattern, and the intersections thereof are fixed to each other and arranged in parallel. A rectangular fuel storage cell 33 is formed and is integrally mounted on the base 3. The base 3 is fixed to the bottom surface of the fuel storage pool by bolts and nuts (not shown), and the plurality of fuel assemblies 7 are individually inserted into the fuel storage cells 33 and seated on the base 3. It is fitted and supported by (not shown).

More specifically, as shown in FIGS. 2 to 6, the strip-shaped partition plate 32 has a length corresponding to the axial length of the fuel assembly 7 and a width corresponding to the width of one fuel storage cell 33. have. On the other hand, the flat partition plate 31 has a length corresponding to the axial length of the fuel assembly 7 and a width corresponding to the entire width of a spent fuel storage rack in which a plurality of fuel storage cells 33 are arranged in parallel. A plurality of perforation holes 37 are provided for every one cell pitch of the fuel storage cells 33. The inner diameter of each of the drill holes 37 is set to be smaller than the plate thickness of the strip-shaped partition plate 32, and one end thereof is tapered to have a chamfered shape. The pin 34 has a shaft 38 having an outer diameter that can be inserted into the plurality of perforation holes 37 of the flat partition plate 31.
It has a head portion 39 which is shaped and dimensioned so as not to protrude from the surface of the flat partition plate when the pin 34 is fitted into the tapered chamfered portion and is inserted into the drilled hole 37.

A plurality of flat partition plates 31 and strip partition plates 32 as described above are arranged so as to intersect each other at a right angle on the plane of the spent fuel storage rack 30, and one side of the strip partition plates 32 is arranged. After the end face and the flat plate-like partition plate 31 are fixed by welding 36, the adjacent flat plate-like partition plate 31 is cut into the holes 3
7 is arranged so as to face one side end surface of the plurality of fixed strip-shaped partition plates 32, the pin 34 is inserted into the drill hole 37, and the head 39 thereof is in close contact with the tapered chamfered portion of the drill hole 37. After being pressed so that it is firmly fixed to the plurality of strip-shaped partition plates 32 by stud welding 35, a plurality of fuel storage cells 33 arranged in parallel are formed.

To explain this in more detail, a plurality of strip-shaped partition plates 32 are arranged at right angles to the positions of the perforation holes 37 of the flat plate-shaped partition plate 31 so that their side end surfaces are in contact with each other, and the contact is made. Side end face of the strip-shaped partition plate 32 and the flat plate-shaped partition plate 31
And are fixed by welding 36, and the first stage is assembled. Next, the flat plate-shaped partition plate 31 is placed so that the drill holes 37 of the flat plate-shaped partition plate 31 of the second stage come to the side end faces of the band-shaped partition plate 32 of the first stage.
Put. After that, the pin 34 is inserted from the drill hole 37 of the second flat partition plate 31, and the head 39 of the pin 34 is drilled into the drill hole 3.
After pressing so as to come into close contact with the tapered chamfered part of 7,
The intersection of the plurality of strip-shaped partition plates 32 and the flat plate-shaped partition plate 31 is firmly fixed by the stud welding 35. The spent fuel storage rack 30 is manufactured by sequentially stacking and assembling the strip partition plate 32 and the flat partition plate 31 in the same procedure.

As described above, according to the structure of the spent fuel storage rack of the present invention, the flat partition plate 31 and the strip partition plate 3 are provided.
The machining time of 2 can be shortened, and no fitting adjustment etc. is required at the time of assembling, and the work is simplified.
It is possible to obtain the spent fuel storage rack 30 which has a short manufacturing period and is excellent in economic efficiency.

In order to make the spent fuel storage rack dense by reducing the pitch between the fuel storage cells 33, the material of the flat partition plate 31 and the band partition plate 32 is excellent in neutron absorption capacity, And it is desirable to use boron-added stainless steel that is also effective as a strength member, but in some cases, for example, one or both of the flat partition plate 31 and the strip partition plate 32 may be normal stainless steel every other sheet, Alternatively, members made of materials having excellent mechanical strength and neutron absorption ability may be appropriately mixed and used.

Next, a reference example will be described. In the reference example shown in FIGS. 7 to 9, instead of the pin and stud welding of the above-mentioned embodiment, the intersection of the flat partition plate 40 and the strip partition plate 32 is fixed by plug welding 42. In this case, it is only necessary to set the inner diameter of the perforation hole 41 of the flat partition plate 40 to be smaller than the plate thickness of the strip partition plate 32, and the tapered chamfering process is unnecessary. Therefore, it is possible to further reduce the processing time of the flat partition plate 40, and it is possible to reduce the number of parts and the assembly time by eliminating the need for pins.

Further, in the reference example shown in FIGS. 10 to 12, the inner diameter of the perforation hole 44 of the partition plate 43 is made larger than the plate thickness of the strip-shaped partition plate 32, and the flat partition plate 43 and the strip-shaped partition plate 32 are separated. The joining is performed by fillet welding 45. In this case, at the time of assembly, the first band-shaped partition plate 32
The flat plate-like partition plate 43 is placed so that the cutout holes 44 of the second-stage flat plate-like partition plate 43 come to the side end surface of
Since the perforation hole 44 is larger than the plate thickness of the strip-shaped partition plate 32, the alignment becomes simple and the assembly time can be further shortened.

[0021]

According to the present invention, the shapes of the band-shaped partition plate and the flat plate-shaped partition plate are simple, the man-hours and time required for machining them can be shortened and greatly shortened, and the assembling thereof can be facilitated. The period can be shortened and the economy can be improved.

[Brief description of drawings]

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

FIG. 2 is an enlarged sectional view taken along the line II-II in FIG.

FIG. 3 is a sectional view taken along the line III-III in FIG.

FIG. 4 is a sectional view taken along the line IV-IV in FIG.

5 is an enlarged perspective view showing a pin in the embodiment of FIG. 1. FIG.

FIG. 6 is an exploded perspective view illustrating a combined state of partition plates in the embodiment of FIG.

[7] (corresponding to taken along the line II-II enlarged sectional view of FIG. 1) a cross-sectional view showing a spent fuel storage rack in Reference Example.

8 is a sectional view taken along the line VIII-VIII in FIG.

9 is an exploded perspective view illustrating a combined state of partition plates in the reference example of FIG. 7.

[10] (corresponding to taken along the line II-II enlarged sectional view of FIG. 1) a cross-sectional view showing a spent fuel storage rack in Reference Example.

11 is a view taken along the line XI-XI in FIG.

12 is an exploded perspective view illustrating a combined state of partition plates in the reference example of FIG.

FIG. 13 is a plan view illustrating a conventional spent fuel storage rack.

14 is a sectional view taken along the line XIV-XIV in FIG.

15 is a sectional view taken along the line XV-XV in FIG.

16 is a sectional view taken along the line XVI-XVI in FIG.

FIG. 17 is an exploded perspective view illustrating a combined state of partition plates in the spent fuel storage rack of FIG.

[Explanation of symbols]

3 ... Base 7 ... Fuel assembly 20,30 …… Spent fuel storage rack 21 ... the first grid plate 22 ... Second lattice plate 23, 33 ... Fuel storage cell 31, 40, 43 ... Flat partition plate 32 …… Band-shaped partition plate 34 ...... pin 35: Stud welding 36 ... Welding 37, 41, 44 ... drill hole 42 ... Plug welding 45 ... Fillet welding

─────────────────────────────────────────────────── ─── Continuation of the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) G21C 19/07 G21C 19/32 G21F 9/36

Claims (3)

(57) [Claims] 1. A spent fuel storage rack comprising a combination of partition plates in a grid pattern, wherein a flat plate partition plate having a plurality of holes and a band partition plate arranged at a right angle to the flat plate partition plate. The side end surfaces are combined in a grid pattern so as to abut the hole positions of the flat partition plate, and a shaft having a diameter that can be inserted into the holes provided in the flat partition plate and the
Use a pin with a head with a diameter larger than the hole,
Insert it into the hole of the strip and press it against the side end surface of the strip-shaped partition plate
A spent fuel storage rack characterized by integrating the intersections by welding . 2. The hole of the flat partition plate is seated at one end thereof.
And hold the height of the pin head with the counterbore.
2. The spent fuel storage rack according to claim 1, wherein the depth is less than the depth of the spent fuel storage rack. 3. A method for manufacturing a spent fuel storage rack comprising partition plates combined in a grid pattern, wherein a plurality of strip partition plates are vertically attached to the flat partition plate by welding in advance, and the other end of the strip partition plates is attached. It can be inserted into the hole provided in the flat partition plate after combining so that the holes of another flat partition plate
A pin with a larger diameter shaft and a larger diameter head than the hole
Inserted into the hole of the flat partition plate, the side end surface of the strip partition plate
And press the stud together to integrate the intersections by stud welding .
A method for manufacturing a spent fuel storage rack, characterized by assembling a spent fuel storage rack by repeating this procedure.