JP5959843B2 - Rack support structure - Google Patents

Description

  The present invention relates to a rack support structure.

  Conventionally, spent nuclear fuel (used nuclear fuel rods) generated at a nuclear power plant is stored and stored in a nuclear fuel storage facility. Such spent nuclear fuel is stored in a rack cell of a fuel storage rack as a nuclear fuel assembly and stored in a storage pit of a nuclear fuel storage facility. At this time, water is stored in the storage pit, and a plurality of nuclear fuel storage racks are arranged and stored in the water, so that the decay heat is cooled and kept below the criticality, and radiation is shielded. I am doing so.

  Here, as a general method of fixing the nuclear fuel storage rack to the storage pit, a method of bolting the nuclear fuel storage rack to the floor of the storage pit is widely known (see Patent Document 1 below).

On the other hand, as a method for fixing the nuclear fuel storage rack to the storage pit, it is desired to ensure sufficient seismic performance so that the nuclear fuel storage rack will not fall over and be damaged during an earthquake.
Therefore, a support structure for supporting the fuel storage rack by slidably mounting the rack base plate provided below the fuel storage rack without restraining the base plate fixed to the floor of the storage pit. Is employed (see Patent Document 2 below).
This support structure has the merit of ensuring seismic performance by preventing the fuel storage rack from overturning by sliding the fuel storage rack relative to the floor of the storage pit during an earthquake. .

Also, a support structure is adopted in which the fuel storage rack is fixed to the floor of the storage pit with bolts or the like and fixed to the wall with a spring interposed (see Patent Document 1 below).
According to this support structure, in the event of an earthquake, the nuclear fuel storage rack can be moved horizontally within a predetermined range due to the vibration caused by the earthquake, and since it is supported by the wall by the spring, there is no risk of falling down. There was a merit that performance could be secured.

  In recent years, it has been desired to secure seismic performance in the existing nuclear fuel storage rack that is bolted to the floor, which is a general fixing method described above.

JP-A-10-39087 Japanese Utility Model Publication No. 58-47797

However, no seismic reinforcement technology has been proposed for improving the seismic performance of existing nuclear fuel storage racks bolted to the floor of the storage pit.
For example, the support structure described in Patent Document 2 may be applied to the existing nuclear fuel storage rack fixed with bolts. In this case, since rack racks and pedestals must be interposed between the existing nuclear fuel storage rack and the floor of the storage pit, the nuclear fuel storage rack is once transported outside the storage pit. Work. Therefore, it is not realistic and the support structure described in Patent Document 2 cannot be simply applied.

In addition, when the support structure described in Patent Document 1 is applied, by using a spring having a large spring constant, it is possible to reliably absorb the impact force during an earthquake and prevent the nuclear fuel storage rack from toppling over. Can do.
Here, since the water temperature of the storage pit rises in summer, the nuclear fuel storage rack expands thermally. In this case, since a spring having a large spring constant cannot absorb the thermal expansion, a spring having a small spring constant is optimal. However, in the case of a spring having a small spring constant, the displacement of the nuclear fuel storage rack with respect to the impact force of an earthquake is larger than that of a spring having a large spring constant. There is a problem that it cannot be absorbed.

  The present invention has been made in consideration of such circumstances, and rack support provided with a support structure capable of absorbing the thermal expansion of the rack and absorbing the impact force during an earthquake to improve the earthquake resistance. Provide structure.

In order to achieve the above object, the present invention employs the following means.
That is, the rack support structure according to the present invention includes a rack provided on the floor of the facility,
A rack support structure comprising a support structure body for connecting the rack and a wall surface of the facility, wherein the support structure body includes a first spring member connected to the wall surface and one end connected to the first spring member. And a second spring member having a spring constant different from that of the first spring member, the other end being connected to a side wall of the rack.

  In such a rack support structure, the spring member having the larger spring constant of the first spring member and the second spring member provided between the rack and the wall surface of the facility absorbs the impact force at the time of the earthquake and is seismic resistant. The spring member with the smaller spring constant can absorb the thermal expansion of the rack.

  In the rack support structure according to the present invention, it is preferable that the rack contains spent nuclear fuel, and the facility is a pool filled with water.

  According to this configuration, the impact force and the thermal expansion of the rack during an earthquake can be reliably absorbed in a pool that is a facility for storing spent nuclear fuel.

  Furthermore, in the rack support structure according to the present invention, the second spring member may be connected to a side wall of the rack via a buffer member.

  Thereby, since a buffer member absorbs the impact force at the time of an earthquake, the impact force which acts on a rack can be reduced.

  Furthermore, in the rack support structure according to the present invention, the second spring member may be detachably connected to the side wall of the rack in a contact state.

  Thereby, when a rack inclines at the time of an earthquake, it can prevent that a 1st spring member and a 2nd spring member are crushed by an impact force by shifting a contact position with a rack.

  Furthermore, in the rack support structure according to the present invention, the support structure body may include a case member that houses the first spring member and the second spring member.

  Thereby, since the first spring member and the second spring member are housed inside the case member, the first spring member and the second spring member can be expanded and contracted without being affected by the water flow during an earthquake. The shock force can be absorbed reliably.

  Furthermore, in the rack support structure according to the present invention, the case member houses a first spring member therein, the first case member disposed along the direction in which the first spring member expands and contracts, and the first case member A second case member that is disposed on an outer periphery of the case member, accommodates the second spring member therein, and is disposed along the extending and contracting direction, and the first case member and the second case member are , And may be connected so as to be relatively movable in the extending and contracting direction.

  Thereby, since the first spring member and the second spring member can move relative to each other, one spring member surely absorbs the thermal expansion of the rack, and the other spring member reliably absorbs the impact force during the earthquake. Can do.

  Furthermore, in the rack support structure according to the present invention, a guide member may be interposed between the first case member and the second case member.

  As a result, the first case member and the second case member can smoothly move relative to each other, and the first spring member and the second spring member can be extended. Can be absorbed.

  Furthermore, in the rack support structure according to the present invention, the rack may be fixed to the floor surface.

  Thereby, since there is no possibility that the rack will fall, safety can be improved.

  Furthermore, in the rack support structure according to the present invention, the case member may be polygonal when viewed in cross section.

  As a result, when a force acts in a direction in which the rack is tilted and the case member is twisted at the time of an earthquake, the corners of the first case member and the corners of the second case member are brought into contact with each other and locked. The movement of the member and the second case member in the twisting direction can be restricted. Therefore, since the case member is not twisted and damaged during an earthquake, the impact force can be absorbed.

  Furthermore, in the rack support structure according to the present invention, a hole penetrating the inside and the outside may be formed in the case member.

  As a result, even when the liquid or the like existing inside the case member oscillates, the liquid can be led out from the hole, so that thermal expansion and impact force are absorbed without being affected by the oscillation. be able to.

  According to the rack support structure of the present invention, it is possible to absorb the thermal expansion of the rack and absorb the impact force at the time of an earthquake and improve the earthquake resistance.

It is a schematic whole block diagram of the facility (storage pit) using the rack support structure concerning one embodiment of the present invention. It is a perspective view of the rack of FIG. FIG. 2 is a top view of the rack of FIG. 1. It is typical sectional drawing explaining the rack support structure which concerns on one Embodiment of this invention. (A) When a rack support structure according to an embodiment of the present invention is normal, (b) When a rack is tilted to one rack support structure side at the time of an earthquake, (c) The rack is opposite to one rack support structure at the time of an earthquake It is sectional drawing at the time of inclining to the side.

Hereinafter, a rack support structure 1 according to an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 shows a nuclear fuel storage facility 2 using a rack support structure 1 according to an embodiment of the present invention.
The nuclear fuel storage facility 2 includes a storage pit 3 (pool) in which water is stored, and includes a rack support structure 1 having a nuclear fuel storage rack 11 (rack) in the water.

  The rack support structure 1 includes, for example, a nuclear fuel storage rack 11 that stores spent nuclear fuel generated at a nuclear power plant, and a support structure main body 21 that connects the nuclear fuel storage rack 11 and the wall surface of the side wall 3 a of the storage pit 3. It has.

A plurality of nuclear fuel storage racks 11 are arranged in two horizontal directions perpendicular to the storage pit 3. As shown in FIGS. 2 and 3, the nuclear fuel storage rack 11 extends in the vertical direction and extends in two horizontal directions in which the rack cells 12 that contain spent nuclear fuel (used nuclear fuel rods) are orthogonal to each other. The adjacent rack cells 12 are alternately arranged so as to have a gap 13 therebetween.
The nuclear fuel storage rack 11 is a so-called self-supporting fuel rack, and is provided on the floor surface 3 b of the storage pit 3.
Here, FIG. 4 is a cross-sectional view schematically showing the rack support structure. As shown in FIG. 4, in the present embodiment, four base frames 4 placed on the floor surface 3b of the storage pit 3 and fixed with the first bolts 5 are arranged in one direction. A total of eight nuclear fuel storage racks 11 in two other directions orthogonal to the direction are placed. Each nuclear fuel storage rack 11 is fixed to the base frame 4 with a second bolt 14.
In addition, the said number is an example and can be selected suitably.

As shown in FIGS. 4 and 5 (a), support structure bodies 21 are respectively provided between the side walls 3a of the storage pits 3 on both sides of the nuclear fuel storage rack 11 and the nuclear fuel storage rack 11 in a cross-sectional view. ing.
The support structure main body 21 includes a first spring member 31 connected to the wall surface of the side wall 3a of the storage pit 3, a second spring member 41 connected to the first spring member 31, a first spring member 31, and It has a case member 50 that houses the second spring member 41, and a buffer member 61 that is interposed between the case member 50 and the nuclear fuel storage rack 11.
In addition, it is preferable that the 1st spring member 31, the 2nd spring member 41, and the case member 50 are metal from the point which prevents degradation by a radioactive substance.

  As shown in FIG. 5A, one end of the first spring member 31 is connected to the wall surface of the side wall 3 a of the storage pit 3, and a first attachment member 32 is provided at the other end.

The second spring member 41 is configured with a spring constant smaller than the spring constant of the first spring member 31, one end connected to the first mounting member 32, and the other end provided to the case member 50. It is connected to the member 53. In other words, one end of the second spring member 41 is connected to the first spring member 31 via the first mounting member 32.
The first spring member 31 and the second spring member 41 are preferably disc springs that exhibit a large reaction force with a small displacement, for example.

  The case member 50 includes a first case member 51 that houses the first spring member 31 therein, a second case member 52 that houses the second spring member 41 therein, and the first case member 51 and the second case. And a first guide member 54 interposed between the member 52 and the member 52. Further, the case member 50 has a polygonal shape such as a hexagon when viewed in cross section.

  The first case member 51 is a cylindrical member and is disposed along the direction in which the first spring member 31 expands and contracts (hereinafter referred to as the expansion and contraction direction). A second guide member 57 is provided between the first case member 51 and the first attachment member 32, and the first spring member 31 interposes the first attachment member 32 and the second guide member 57. The inside of the first case member 51 can be extended. The first case member 51 is formed with a first through hole 51a penetrating the inside and the outside.

The second case member 52 is a bottomed cylindrical member, and an opening 55 is formed on the outer periphery of the first case member 51 along the direction in which the second spring member 41 expands and contracts (stretching direction). It is arranged toward the side. A second attachment member 53 is fixed inside the bottom portion 56. Further, the second case member 52 is formed with a second through hole 52a penetrating the inside and the outside.
Thus, the 1st case member 51 and the 2nd case member 52 are connected so that relative movement is possible in the expansion-contraction direction.

  The first guide member 54 is provided at a portion where the first case member 51 and the second case member 52 overlap, and the first case member 51 and the second case member 52 can smoothly move relative to each other in the expansion / contraction direction. Have a role.

  The buffer member 61 has a substantially spherical shape in the present embodiment, and is provided outside the bottom portion 56 of the second case member 52, and the buffer member 61 contacts the side wall 11 a of the nuclear fuel storage rack 11 in a normal state. It touches. In this way, the second spring member 41 disposed inside the second case member 52 is connected to the side wall 11a of the nuclear fuel storage rack 11 via the buffer member 61 so as to be separable. .

Next, the operation | movement at the time of the earthquake of the rack support structure 1 which concerns on this embodiment is demonstrated.
As shown in FIG. 4, support structure main bodies 21 are respectively provided between the side walls 3 a on both sides of the storage pit 3 and the nuclear fuel storage rack 11 in a sectional view, and as shown in FIG. In a normal state, the first spring member 31 and the second spring member 41 of each support structure main body 21 are extended, and the buffer member 61 and the nuclear fuel storage rack 11 are in contact with each other.
Here, when an impact that tilts toward one rack support structure 1 occurs during an earthquake as shown in FIG. 5B, the first spring member 31 and the second spring member 41 are compressed, The second case member 52 moves to the first spring member 31 side. In this way, the nuclear fuel storage rack 11 is supported by the reaction force of the first spring member 31 and the second spring member 41, particularly the reaction force of the first spring member 31 having the larger spring constant.
On the other hand, as shown in FIG. 4, the support structure main body 21 provided on the side opposite to the direction in which the nuclear fuel storage rack 11 is inclined is in the state shown in FIG. That is, the first spring member 31 and the second spring member 41 remain in a normal extended state, and the nuclear fuel storage rack 11 is separated from the buffer member 61.

In the rack support structure 1 configured as described above, the first case member 51 and the second case member 52 are relatively movable during an earthquake, so the first spring member 31 and the second spring member 41 are compressed. The reaction force of the first spring member 31 and the second spring member 41 acts on the nuclear fuel storage rack 11. Here, since the reaction force of the first spring member 31 having the larger spring constant is larger than the reaction force of the second spring member 41, the first spring member 31 particularly absorbs the impact force during the earthquake. Seismic resistance can be improved. Thereby, the bending moment acting on the nuclear fuel storage rack 11 can be reduced, and the nuclear fuel storage rack 11 can be reliably supported.
Further, by absorbing the impact force by the first spring member 31 and the second spring member 41, it is possible to prevent stress from concentrating on the second bolt 14 that fixes the nuclear fuel storage rack 11 to the base frame 4. it can. Therefore, since there is no possibility that the second bolt 14 is damaged due to concentration of stress, the nuclear fuel storage rack 11 can be stably supported even during an earthquake.

  In addition, when the water temperature of the storage pit 3 rises and the nuclear fuel storage rack 11 thermally expands, the thermal expansion is caused by the second of the first spring member 31 and the second spring member 41 having the smaller spring constant. Since it can be absorbed by the spring member 41, the nuclear fuel storage rack 11 can be reliably supported.

  Further, in a normal state, the nuclear fuel storage rack 11 can be supported from the horizontal direction by the reaction force of the first spring member 31 and the second spring member 41 in contact with the nuclear fuel storage rack 11. The second bolt 14 fixed to the base frame 4 can be reliably supported from the vertical direction.

  Further, when the support structure main body 21 is attached to the existing storage pit 3, the first case member 51 and the first spring member 31 are fixed to the side wall 3 a of the storage pit 3, and the buffer member 61 is attached to the nuclear fuel storage rack 11. It is only necessary to contact the side wall 11a. Therefore, it is not necessary to provide a mounting jig such as a bolt on the nuclear fuel storage rack 11 side, so that seismic reinforcement can be performed with easy construction and the safety of the spent nuclear fuel can be ensured.

Further, when the nuclear fuel storage rack 11 is tilted during an earthquake, the shock absorbing member 61 can reduce the impact force.
Further, even when the nuclear fuel storage rack 11 is tilted, the buffer member 61 has a substantially spherical shape, so that the portion that contacts the nuclear fuel storage rack 11 can be a surface instead of a point. Therefore, since a large contact area can be secured, the impact force can be stably borne without being concentrated locally.

  A first guide member 54 is provided between the first case member 51 and the second case member 52, and a second guide member 57 is provided between the first mounting member 32 and the first case member 51. It has been. Therefore, the first case member 51 and the second case member 52 can smoothly move relative to each other in the expansion / contraction direction, and the first spring member 31 and the second spring member 41 can reliably expand and contract without being caught, The nuclear fuel storage rack 11 can be supported.

  Further, since the second spring member 41 is in contact with the side wall 11a of the nuclear fuel storage rack 11, when the nuclear fuel storage rack 11 is inclined during an earthquake, the nuclear fuel storage rack 11 and the buffer member 61 are in contact with each other. The position can be moved upward and supported. Therefore, the first spring member 31 and the second spring member 41 can be prevented from being crushed by the impact force.

Even when the water flow in the storage pit 3 is disturbed by an impact during an earthquake, the first spring member 31 and the second spring member 41 are accommodated in the first case member 51 and the second case member 52, respectively. Therefore, it can expand and contract without being affected by the water flow, and the impact force can be reliably absorbed.
Even when there is a fallen object in the storage pit 3 or an external force is generated, the first spring member 31 and the second spring member 41 are accommodated in the first case member 51 and the second case member 52. There is no possibility that the first spring member 31 and the second spring member 41 are damaged.

  Further, when the nuclear fuel storage rack 11 is inclined during an earthquake and a force acts on the first case member 51 and the second case member 52 in a direction twisting with respect to the extending direction, the first case member 51 and the second case Since the member 52 has a polygonal shape in cross-sectional view, the corner of the first case member 51 and the corner of the second case member 52 come into contact with each other and are locked. Therefore, since the movement of the first case member 51 and the second case member 52 in the twisting direction can be restricted, the first case member 51 and the second case member 52 are not twisted and damaged during an earthquake. Can absorb impact force.

  In addition, when water existing inside the first case member 51 and the second case member 52 sways during an earthquake, the first through holes 51a formed in the first case member 51 and the second case member 52 and The water can be led out from the second through hole 52a. Therefore, thermal expansion and impact force can be absorbed without being affected by the oscillation.

  It should be noted that the assembly procedure shown in the above-described embodiment, or the shapes and combinations of the constituent members are examples, and various modifications can be made based on design requirements and the like without departing from the gist of the present invention.

  For example, the arrangement relationship between the first spring member 31 and the second spring member 41 is reversed so that the first spring member 31 having a large spring constant is placed on the nuclear fuel storage rack 11 side and the spring constant is placed on the side wall 3a side of the storage pit 3. A small second spring member 41 may be provided. Even in this case, since the first spring member 31 and the second spring member 41 can be expanded and contracted as in the above-described embodiment, the thermal expansion and impact force are exerted by the reaction force of the first spring member 31 and the second spring member 41. Can be absorbed.

  The buffer member 61 and the nuclear fuel storage rack 11 may be joined. In this case, the support structure main body 21 can reliably support the nuclear fuel storage rack 11 and the first spring member 31 and the second spring member 41 can be expanded and contracted. The impact force and thermal expansion can be absorbed by the reaction force of the spring member 41.

  In the present embodiment, the spring member is composed of the first spring member 31 and the second spring member 41 which are different spring constants, but may be composed of three or more types of spring constants. In this case, the impact force and thermal expansion can be absorbed by a spring member having an optimal spring constant according to the magnitude of the impact force and thermal expansion.

  Moreover, in this embodiment, although the through-holes 51a and 52a are formed in each of the 1st case member 51 and the 2nd case member 52, it is good also as being formed in either one. Even in this case, water swung inside the case member 50 can be led out to the outside, so that thermal expansion and impact force can be absorbed without being affected by the swing.

1 ... Rack support structure 2 ... Nuclear fuel storage facility (facility)
3b ... Floor of storage pit 3 (facility floor)
11 ... Nuclear fuel storage rack (rack)
11a: Side wall of the nuclear fuel storage rack 11 (side wall of the rack)
DESCRIPTION OF SYMBOLS 21 ... Support structure main body 31 ... 1st spring member 41 ... 2nd spring member 50 ... Case member 51 ... 1st case member 51a ... 1st through-hole (hole)
52 ... Second case member 52a ... Second through hole (hole)
54. First guide member (guide member)
61 ... Buffer member

Claims (10)

A rack provided on the floor of the facility;
A rack support structure comprising a support structure main body for connecting the rack and a wall surface of the facility,
The support structure body is
A first spring member connected to the wall surface;
With one end connected to said first spring member, the other end is connected to the side wall of the rack, possess a second spring member that is different spring constants than said first spring member,
The spring member with the larger spring constant of the first spring member and the second spring member absorbs the impact force at the time of the earthquake, and the spring member with the smaller spring constant can absorb the thermal expansion of the rack. Features a rack support structure. The rack support structure according to claim 1,
The rack contains spent nuclear fuel,
The rack support structure according to claim 1, wherein the facility is a pool filled with water. The rack support structure according to claim 1 or 2,
The rack support structure, wherein the second spring member is connected to a side wall of the rack via a buffer member. In the rack support structure according to any one of claims 1 to 3,
The rack support structure, wherein the second spring member is connected to the side wall of the rack so as to be separated in a contact state. In the rack support structure according to any one of claims 1 to 4,
The rack support structure according to claim 1, wherein the support structure main body includes a case member that accommodates the first spring member and the second spring member. The rack support structure according to claim 5,
The case member houses a first spring member therein, and a first case member disposed along a direction in which the first spring member expands and contracts;
A second case member disposed on an outer periphery of the first case member, containing the second spring member therein, and disposed along the extending and contracting direction;
The rack support structure, wherein the first case member and the second case member are connected so as to be relatively movable in the extending and contracting direction. The rack support structure according to claim 6,
A rack support structure, wherein a guide member is interposed between the first case member and the second case member. The rack support structure according to any one of claims 1 to 7,
The rack support structure, wherein the rack is fixed to the floor surface. The rack support structure according to claim 6 or 7,
The rack support structure, wherein the case member has a polygonal shape in a cross-sectional view. The rack support structure according to any one of claims 6 to 9,
A rack support structure, wherein a hole penetrating the inside and the outside is formed in the case member.

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