JP2012141243A - Buffer for cask - Google Patents

Abstract

PROBLEM TO BE SOLVED: To appropriately mitigate impact load to a lid part of a cask.SOLUTION: An area filled with impact absorption members 20 is divided into at least a lid part upper surface area 21 and a lid part outer peripheral surface area 22. The lid part outer peripheral surface area 22 is filled with, as the impact absorption members 20, first impact absorption members 22A and second impact absorption members 22B whose compression strength is higher than that of the first impact absorption members 22A. The first impact absorption members 22A are annularly arranged so as to cover an outer peripheral surface 3b of an end part of a lid part 3, and the second impact absorption members 22B are annularly arranged so as to cover the first impact absorption members 22A from a radial outside of a cask 1 and also so as to cover, along the axis direction of the cask 1, the first impact absorption members 22A from the side having the lid part upper surface area 21 and from the opposite side thereof.

Description

  The present invention relates to a cushion for a cask used in a cask that stores radioactive materials such as spent fuel generated from a nuclear reactor core, and more particularly to an arrangement of shock absorbing members filled in an outer shell.

In general, spent fuel is stored in a cooling pool provided in a nuclear power plant until the radiation dose drops below a certain level, and then stored in a cask with a shielding function and a sealing function. Transported. Since the cask is heavy, in case of a fall accident during transportation and handling, the cask has a vertical fall that falls in a posture where the central axis of the cask is vertical (hereinafter simply referred to as vertical fall). Drops at various angles, such as horizontal drops that fall in a horizontal position (hereinafter simply referred to as horizontal drops), and corner drops that fall in a posture with a central angle of the cask (hereinafter simply referred to as corner drops) However, it is obliged to have a predetermined shielding function and sealing function.
Therefore, during transportation and handling, a countermeasure is usually taken that a shock absorber for cask is attached to the upper and lower ends of the cask to sufficiently reduce the impact in the event of a fall.

  By the way, in order to increase the fuel storage efficiency of the cask, the cask buffer body is required to suppress the fall acceleration as much as possible within the allowable deformation amount in terms of strength design. For this reason, it is desirable that the material (shock absorbing member) that absorbs the impact is such that the compressive stress exhibits a constant value from the beginning to the end of shrinkage, and wood is most often used.

In a conventional cask buffer, for example, as disclosed in Patent Document 1, shock absorbing members that share and absorb the load caused by the horizontal drop, the load caused by the vertical drop, and the load caused by the corner drop are disposed, respectively. It has been proposed.
In this cask shock absorber, the shock absorbing member that absorbs the load caused by the vertical drop is arranged with the direction of strength in the axial direction in the inner peripheral area in contact with the end face of the cask, and also absorbs the load caused by the horizontal drop. The shock absorbing member is arranged in the radial direction in the region in contact with the side surface of the cask, and further, the shock absorbing member that absorbs the load due to the corner drop has the strength in the outer peripheral region in contact with the end surface of the cask. The direction to have is arrange | positioned toward the radial direction.
According to such a cask buffer body, it is possible to appropriately absorb the impact load of various postures when the cask is dropped by arranging the shock absorbing member as described above, and suppress the impact acceleration to a low level. The amount of displacement can be kept low.

Further, in the cask buffer disclosed in Patent Document 2, the interior of the buffer is partitioned into a plurality of regions, and the grain direction is aligned in the same direction in one region, and in relation to adjacent regions Have been proposed in which the grain directions are aligned in different directions.
According to the cask buffer, the impact force can be received and absorbed in a wide range by biasing the deformation force of the wood due to the impact load to the adjacent wood.

Japanese Patent No. 4111037 Japanese Patent No. 4410072

By the way, in the horizontal drop or corner drop described above, the impact load tends to concentrate on the lid portion of the cask. The lid portion is an important part that constitutes the sealed region, and is also a part that is required to further reduce the impact load.
As measures against the impact load on the lid, there are methods such as increasing the area of the buffer body relative to the cask or forming the flange of the cask thick. However, the maximum size of the cask is determined due to the restrictions of the equipment when transporting, and if the area of the buffer body is increased as described above, or if the flange portion of the cask is formed thick, that amount, The fuel storage area decreases, and the fuel storage efficiency decreases. For this reason, there is a need for a technique for improving the shock absorbing capacity without changing the buffer region.

  Here, Patent Document 1 and Patent Document 2 propose to devise the grain direction and arrangement of the impact absorbing member for the purpose of enduring impact from all directions, and to mitigate the impact on the entire cask. No method has been proposed for mitigating the impact load on the lid.

  An object of the present invention is to provide a cask buffer body that can suitably reduce an impact load applied to a cask lid.

  In order to achieve the above-described object, the present invention includes an outer shell that is externally provided around at least a lid portion of a cask having a substantially cylindrical shape, and an impact absorbing member that is filled in the outer shell. It is a bottom cylindrical cask buffer, and the region filled with the impact absorbing member includes at least a lid upper surface region covering the upper surface of the lid portion and a lid outer peripheral surface covering the outer peripheral surface of the lid portion. The lid outer peripheral surface area includes a first shock absorbing member as the shock absorbing member and a second shock absorbing member having a higher compressive strength than the first shock absorbing member. The first shock absorbing member is arranged in an annular shape so as to cover the outer peripheral surface of the distal end portion of the lid portion, and the second shock absorbing member is formed of the cask. Covering the first shock absorbing member from the outside in the radial direction And, along the axial direction of the cask to cover the first impact absorbing member from the side opposite to a side of the said lid top region, it characterized in that it is arranged in an annular.

  According to this invention, it arrange | positions so that the 1st shock absorption member arrange | positioned cyclically | annularly may be covered on the outer peripheral surface of the front-end | tip part of a cover part, and the diameter of a cask with respect to this 1st shock absorption member. Since the second shock absorbing member is arranged so as to cover from the outside in the direction and from the side opposite to the side having the lid upper surface region along the axial direction of the cask, for example, when the cask falls horizontally When a corner is dropped, immediately after the impact load is input, the first impact absorbing member having a smaller crushing stress is deformed. As the deformation increases, the impact load generated in the vicinity of the lid is absorbed by the second impact absorbing member. More members become responsible. Thereby, the impact load which the 1st impact-absorbing member takes can reduce, and the impact to a cover part can be weakened. In other words, the second shock absorbing member can be given more impact load, and the impact load applied to the tip of the cask lid can be strong as a structural material other than the tip of the lid ( This can be relaxed (absorbed) by acting on a portion having strength.

  ADVANTAGE OF THE INVENTION According to this invention, the shock absorber for cask which can relieve | moderate the impact load to the cover part of a cask suitably is obtained.

It is a schematic cross section which shows the state which mounted | wore the cask with the buffer body for casks concerning 1st Embodiment of this invention. It is a model expanded sectional view which shows the buffer body for casks. (A) (b) is a schematic diagram which shows the direction of the grain of the impact-absorbing member with which a cover part outer peripheral surface area | region is filled. (A) (b) is a schematic diagram which shows the mode of a deformation | transformation of the impact-absorbing member with which a cover part outer peripheral surface area | region is filled. It is a model expanded sectional view which shows the lower buffer body for casks. (A) (b) is a schematic cross section which shows the state which mounted | wore the cask with the buffer body for casks concerning 2nd Embodiment of this invention. It is a schematic cross section which shows the buffer body for casks concerning 3rd Embodiment of this invention. It is a schematic cross section which shows the buffer body for casks of a modification.

  Next, the cask buffer body of the present invention will be described in detail with reference to the drawings as appropriate. In addition, although this embodiment demonstrates the cask 1 for accommodating the spent fuel which generate | occur | produces from a nuclear power station as a radioactive substance, it is not the meaning which limits the kind of spent fuel. Further, in the following description, “upper” and “lower” indicate a state in which the cask 1 is erected (a state in which the cask 1 is erected so that the lid 3 is on the upper side and the bottom of the body 2 is on the lower side). The standard.

As shown in FIG. 1, the cask buffer body 10 of the present embodiment is packaged so as to cover the periphery of the lid 3 at the top of the cask 1 having a substantially cylindrical shape. In preparation for a single drop accident, the impact load on the lid 3 is mitigated against drops at various angles such as vertical drop, horizontal drop, and corner drop.
In addition, although the case where the cask buffer body 10 is externally mounted on the upper portion of the cask 1 will be described as an example, it may be used as an external housing on the lower portion of the cask 1.

The cask 1 has a substantially cylindrical shape, and is a container for storing and transporting spent fuel assemblies 9 in a nuclear power plant. The cask 1 basically includes a bottomed cylindrical body 2 and a lid 3 attached to the upper opening of the body 2.
The body 2 includes an inner cylinder 4 in which a basket (not shown) for storing a spent fuel assembly 9 is housed, a neutron shielding material 5 provided outside the inner cylinder 4, and an outer surrounding the neutron shielding material 5. The cylinder 6 and the trunnion 7 used for lifting and fixing the cask 1 are provided. The cask cushion 10 is externally mounted on the upper end of the cask 1 in the axial direction, and the lower cask 30 is externally mounted on the lower end of the cask 1 in the axial direction. Yes.

Each of the cask buffer body 10 and the cask lower buffer body 30 has a bottomed cylindrical shape with a substantially U-shaped cross section, and the cask end surface portion 10a corresponding to the outer diameters of the upper end portion and the lower end portion of the inner cylinder 4. , 30a (see FIGS. 2 and 5) and mounted so as to cover the upper end portion and the lower end portion of the inner cylinder 4, respectively. The cask buffer body 10 and the cask lower buffer body 30 are fixed to the upper end portion and the lower end portion of the cask 1 with bolts or the like (not shown).
First, the cask buffer 10 will be described, and the cask lower buffer 30 will be described later.
As shown in FIG. 2, the cask buffer 10 includes outer shells 11 and 12 and an impact absorbing member 20 filled in the outer shells 11 and 12, and as shown in FIG. The upper end outer peripheral surface of the cask 1 including the upper surface 3a of the lid portion 3 of the cask 1 and the outer peripheral surface 3b of the tip portion of the lid portion 3 (the outer peripheral surface of the tip portion of the lid portion 3) is protected.

The outer shells 11 and 12 shown in FIG. 2 are formed of a metal material such as corrosion-resistant stainless steel or painted carbon steel in consideration of being used outdoors. A lid upper surface region 21 that covers an upper surface 3a (see FIG. 1, the same applies hereinafter), which is an outer surface of the outer peripheral surface, and an outer peripheral surface 3b (see FIG. 1, the same applies hereinafter) of the tip of the lid 3 (see FIG. 1, the same applies hereinafter). And a lid outer peripheral surface region 22 that covers the cover.
Of these, the lid outer peripheral surface region 22 is divided into two regions 22a and 22b. That is, in the outer shells 11 and 12, the region filled with the shock absorbing member 20 is divided into three regions.
In addition, when the cover part upper surface area | region 21 and the area | region 22a of the cover part outer peripheral surface area | region 22 are comprised with the same material (Balsa material etc. as timber mentioned later), you may comprise these integrally.

Here, the region 22a of the lid outer peripheral surface region 22 is an annular region whose one end has a substantially quadrangular cross section, and the upper end outer peripheral surface of the cask 1 including the outer peripheral surface 3b of the distal end portion of the lid 3 is defined. It is arranged to cover.
The region 22b is an annular region having a substantially L-shaped cross section at one end, and covers the side surface 22a1 of the region 22a from the radially outer side of the cask 1 with respect to the region 22a described above (arrow X1 in the figure). And the lower surface 22b1 of the region 22a is covered in the direction from the lower surface 3c (see FIG. 1; the same applies hereinafter) of the lid 3 toward the upper surface 3a (from the side opposite to the side where the lid upper surface region 21 is located). (Arranged in the direction of arrow Y1 in the figure).

  In the present embodiment, the lid upper surface region 21 is filled with a material having a small compressive strength as the shock absorbing member 20, and the regions 22a and 22b of the lid outer peripheral surface region 22 are between these regions 22a and 22b. Are filled with materials having different compressive strengths (materials deformed by different stresses).

  Since the lid upper surface region 21 is a portion corresponding to the upper part of the cask buffer body 10, structural strength is required to reduce the impact load from the axial direction of the cask 1 and the impact load from the axial direction and the oblique direction of the cask 1. When wood is used as the material to be filled, for example, a balsa material can be used.

In the present embodiment, the shock absorbing member 20 filled in the lid outer peripheral surface region 22 is filled with the first shock absorbing member 22A in the region 22a and from the first shock absorbing member 22A in the region 22b. Also, the second impact absorbing member 22B having a high compressive strength is filled.
The first shock absorbing member 22A is made of a material having a compressive strength of about 10 MPa or less. For example, a polyurethane foam material, a polystyrene foam material, or a balsa material is used as the first shock absorbing member 22A. be able to.
The second impact absorbing member 22B is made of a material having a compressive strength of about 20 to 40 MPa. Examples of the second impact absorbing member 22B include an aluminum tube material, a foam metal material, a far-ply wood material, an oak material, Redwood, rice cedar, and rice hiba can be used.
Here, the compressive strength is represented by a stress-strain diagram (load-displacement curve (not shown)). For example, it can be said that the higher the stress generated during compression, the higher the compressive strength.

Hereinafter, an example in which wood is used for the first shock absorbing member 22A and the second shock absorbing member 22B (for example, a balsa material is used as the first shock absorbing member 22A, and red wood is used as the second shock absorbing member 22B. An example using materials will be described.
Instead of wood, a wooden board having the same compressive strength may be filled inside, or a laminated wood material may be used.

In the first shock absorbing member 22A and the second shock absorbing member 22B, the direction of the wood fiber, which is the grain of the wood, becomes the radial direction of the cask 1 as shown by the arrows in FIGS. Respectively. That is, the orientation with high stress-strain characteristics is arranged in a direction perpendicular to the axial direction of the cask 1.
This is because when wood is subjected to compressive stress in a direction perpendicular to the wood fiber direction, yielding occurs at a low stress and the stress increases as plastic deformation increases, but it is parallel to the wood fiber direction. When compressive stress is applied in the direction, yielding occurs with a greater stress than when compressing in a direction perpendicular to the wood fiber direction, and there is anisotropy that plastically deforms with a substantially constant stress.
In general, it is desirable to reduce the impact load that exhibits a certain stress during plastic deformation. For this reason, the impact load can be suitably reduced by aligning the wood fiber direction with the radial direction, which is the direction in which the load works, so that the impact load on the lid 3 becomes a problem when falling horizontally or cornering. Can do.
Note that the length and width of the wood are set in a range in which the first shock absorbing member 22A is not crushed when the expected maximum impact load is input without greatly increasing the impact force. .

Thus, the lid outer peripheral surface region 22 of the cask buffer 10 is configured by combining the two first impact absorbing members 22A and the second impact absorbing member 22B having different compressive strengths (crushing stresses). Therefore, the following effects can be obtained.
That is, when an impact load is applied to the lid outer peripheral surface region 22 due to a horizontal drop or the like, the side where the first impact absorbing member 22A and the second impact absorbing member 22B are arranged in series in the initial stage where the impact load is applied. In the lid upper surface region 21 side, the first shock absorbing member 22A (only) having a small crushing stress is deformed. Thereafter, when the crushing stress of the first shock absorbing member 22A becomes larger than the crushing stress of the second shock absorbing member 22B, the second shock absorbing member 22B starts to deform.

FIG. 4 shows a schematic diagram of deformation of the first shock absorbing member 22A and the second shock absorbing member 22B (lid outer peripheral surface region 22) when an impact load is applied.
In the case of a horizontal drop, the impact load acts in a direction perpendicular to the axial direction of the cask 1 as shown in FIG. Immediately after the input of the impact load, the first impact absorbing member 22A having a small crushing stress is deformed, and the lid outer peripheral surface region 22 is located on the side corresponding to the lid 3 of the cask 1 (the first impact absorbing member 22A. Side) is greatly deformed (see FIG. 4B).
As the deformation becomes larger in this way, the second shock absorbing member 22B takes on more impact load generated in the vicinity of the lid portion 3 accordingly. For this reason, the impact load to the cover part 3 can be weakened.

  In addition to this, as shown in FIG. 1, since the upper surface 3a of the lid 3 is covered with the lid upper surface region 21 of the cask buffer 10, the first shock absorbing member as described above. When the deformation of 22A becomes large, the impact load that the lid upper surface region 21 takes up becomes larger, whereby the impact load on the lid 3 can be reduced.

  Further, the corner drop can be expected to obtain the same effect by the deformation of the first shock absorbing member 22A as in the case of the horizontal drop as described above.

On the other hand, as shown in FIG. 5, the cask lower shock absorber 30 includes outer shells 31 and 32 and an impact absorbing member 20 filled in the outer shells 31 and 32. Thus, the cask lower end outer peripheral surface including the lower surface 4a of the inner cylinder 4 of the cask 1 and the side outer peripheral surface 4b of the lower surface 4a is protected.
The outer shells 31 and 32 are formed of a metal material such as stainless steel or painted carbon steel in the same manner as the cask buffer 10 described above, and the inside thereof is the lower surface 4a of the inner cylinder 4 (see FIG. 1). Are divided into an inner cylinder lower surface area 33 covering the inner cylinder 4 and an inner cylinder outer surface area 34 covering the side outer peripheral surface 4b (see FIG. 1) of the inner cylinder 4.
The inside of the cask lower shock absorber 30 may be divided into three regions filled with the shock absorbing member 20 in the same manner as the cask shock absorber 10 described above.

  Since the inner cylinder lower surface region 33 is a portion corresponding to the lower portion of the cask lower shock absorber 30, the inner cylinder lower surface region 33 has a structural strength for relaxing the impact load from the axial direction of the cask 1 and the impact load from the axial direction and the oblique direction of the cask 1. When wood is used as a material that is necessary and is filled in the same manner as the lid upper surface region 21 of the cask buffer 10, for example, a balsa material can be used.

Further, the inner cylinder outer peripheral surface region 34 is filled with the second shock absorbing member 22B used in the cask buffer 10. That is, the inner cylinder outer peripheral surface area 34 is configured to have a higher compressive strength than the inner cylinder lower surface area 33.
In the inner cylinder outer peripheral surface region 34, the wood fiber direction, which is the grain of the wood, is arranged so as to be the radial direction of the cask 1 as described in the cask buffer 10.

According to the cask buffer body 10 of the present embodiment described above, the outer peripheral surface 3b of the front end portion of the lid portion 3 is covered with the first shock absorbing member 22A arranged in an annular shape, and this first shock absorption. The member 22A is covered from the outer side in the radial direction of the cask 1 and from the opposite side of the lid upper surface region 21 along the axial direction of the cask 1 (from the lower surface 22b1 side of the region 22a). In addition, since the second shock absorbing member 22B is disposed, for example, when the cask 1 is dropped horizontally or when the corner is dropped, the first shock absorbing member 22A having a smaller crushing stress immediately after an impact load is input. As the deformation is increased and the deformation is increased, the second shock absorbing member 22B takes on more impact load generated in the vicinity of the lid 3.
Thereby, the impact load which the 1st impact-absorbing member 22A takes can reduce, and the impact to the cover part 3 can be weakened. That is, the second shock absorbing member 22B can be given more shock load, and the impact load applied to the tip of the lid 3 of the cask 1 can be used as a structural material other than the tip of the lid 3. It can be relaxed (absorbed) by acting on a strong portion (for example, the inner cylinder 4 or the body portion 2 around the lid portion 3).
Therefore, the cask buffer body 10 can be obtained in which the impact load applied to the lid portion 3 of the cask 1 can be suitably reduced.

(Second Embodiment)
A cask buffer according to the second embodiment will be described with reference to FIGS.
The present embodiment is different from the first embodiment in that the lid 3 is composed of a plurality of lids.

In the case shown in FIG. 6A, the lid portion 3 is composed of two primary lids 3A and secondary lids 3B.
The primary lid 3A is mounted on a lower stage 41 having two upper and lower stages formed on the upper opening edge of the inner cylinder 4 and is attached by a bolt (not shown) so as to close the opening of the inner cylinder 4. The secondary lid 3B is mounted on the upper stage 42 of the stepped portion so as to cover the primary lid 3A and is attached by a bolt (not shown).
Here, between the lower step 41 of the stepped portion and the primary lid 3A, between the upper step 42 of the stepped portion and the secondary lid 3B, or between the primary lid 3A and the secondary lid 3B, there is a ring-shaped not shown. A seal member is disposed.

  The secondary lid 3 </ b> B is placed on the upper stage 42 of the stepped part, and the outer peripheral surface 3 b of the tip part is fitted to the inner surface of the upper end opening edge 43 of the inner cylinder 4. As a result, the outer peripheral surface 3b of the secondary lid 3B is covered with the first shock absorbing member 22A of the cask buffer 10 via the upper end opening edge 43 (between them). . That is, the first shock absorbing member 22A is arranged so as to correspond to the periphery of the connecting portion between the secondary lid 3B and the inner cylinder 4, and the outer peripheral surface 3b of the tip portion of the secondary lid 3B has an upper end opening edge 43 ( And the first shock absorbing member 22A is protected via the outer shell 12).

In the case shown in FIG. 6B, the lid portion 3 is composed of three primary lids 3A, secondary lids 3B, and tertiary lids 3C.
The primary lid 3A and the secondary lid 3B are attached in the same manner as described above, and the tertiary lid 3C is placed on the tip of the upper end opening edge 43 so as to cover the secondary lid 3B, and is not shown in the figure. Is attached by.

  In the present embodiment, it is preferable that the first shock absorbing member 22A has the same thickness as or more than the thickness of the corresponding lid 3 (secondary lid 3B or tertiary lid 3C).

  Also in the cask buffer body 10 of the present embodiment, the same effects as those of the first embodiment can be obtained.

(Third embodiment)
A cask buffer according to a third embodiment will be described with reference to FIG.
The difference between the present embodiment and the first and second embodiments is that a region 22a where the first shock absorbing member 22A is arranged is a cavity 25 partitioned by the second shock absorbing member 22B. Is a point.

The hollow portion 25 is a space surrounded (partitioned) by the side walls 24a and 24b of the second shock absorbing member 22B, the lower surface 20c of the shock absorbing member 20 filled in the lid upper surface region 21, and the outer shell 12. It is comprised by the annular | circular shape by. In the present embodiment, the region 22a where the first shock absorbing member 22A described in the first embodiment is disposed is replaced with a cavity portion 25.
Here, the second shock absorbing member 22 </ b> B corresponds to “the shock absorbing member filled in the outer peripheral surface region of the lid” recited in the claims.

Also in the cask buffer body 10 having such a cavity portion 25, the impact load applied to the tip portion of the lid portion 3 of the cask 1 is applied to a portion that is strong as a structural material other than the tip portion of the lid portion 3. This can be suitably relaxed (absorbed). In this case, even if the cavity portion 25 does not receive any impact load, if the cavity portion 25 is appropriately disposed in the region 22a, the second impact absorbing member 22B is responsible for the impact load. The same effect as the first embodiment can be obtained.
Note that the cavity 22 may be formed by partitioning the region 22a using a partition wall (not shown).

FIG. 8 is a diagram showing a modified cask buffer body. In this modified example, the upper surface 22c1 of the region 22a is also provided with a region 22b filled with the second shock absorbing member 22B.
The region 22b is an annular region having a substantially U-shaped cross section at one end. The region 22b covers the side surface 22a1 of the region 22a from the radially outer side of the cask 1 and the lower surface 3c side of the lid portion 3 with respect to the region 22a. The first impact absorbing member 22A is surrounded from three directions so as to cover the lower surface 22b1 of the region 22a in the direction from the upper surface 3a to the upper surface 3a and further cover the upper surface 22c1 of the region 22a from the upper surface 3a side of the lid 3. .

  Also in this modification, the same effect as the first embodiment can be obtained. Further, since the second impact absorbing member 22B covers the upper surface 22c1 of the region 22a from the upper surface 3a side of the lid portion 3, the impact load applied to the tip portion of the lid portion 3 of the cask 1 is correspondingly applied to the lid portion. It is possible to act on a portion that is strong as a structural material other than the tip portion of 3, and to relax (absorb) it suitably.

In addition, as shown with a dashed-dotted line in FIG. 8, the area | region used as the upper surface of the outer shell 12 enclosed by the area | region 22b is filled with 2nd impact-absorbing member 22B 'which consists of a member similar to 2nd impact-absorbing member 22B. May be.
With this configuration, the impact load applied to the tip of the lid 3 of the cask 1 can be more effectively relaxed (absorbed).

  In the above-described embodiment, the region 22a has a substantially square cross section at one end. However, the region 22a is not limited to this, and the outer peripheral surface 3b of the front end portion of the lid 3 (secondary lid 3B or the like) is formed. If it is configured so as to cover from the side, various shapes such as a triangular shape, a polygonal shape, and a shape including a curved portion can be adopted.

  Further, as the impact absorbing member 20 (first impact absorbing member 22A), granular polyurethane foam or polystyrene can be adopted.

DESCRIPTION OF SYMBOLS 1 Cask 3 Lid part 3a Upper surface 3b Outer peripheral surface 4 Inner cylinder 10 Cask buffer 11, 12 Outer shell 20 Shock absorption member 21 Lid upper surface area 22 Lid outer surface area 22A First impact absorption member 22B Second impact Absorbing member 22a region 22b region 25 cavity

Claims (5)

A cylindrical cask buffer body having a bottomed cylindrical shape, which is provided with an outer shell and a shock absorbing member filled in the outer shell at least around the lid portion of the cask having a substantially cylindrical shape,
The region filled with the impact absorbing member is at least
The lid part upper surface area covering the upper surface of the lid part, and the lid outer peripheral surface area covering the outer peripheral surface of the lid part,
The outer peripheral surface region of the lid is filled with a first impact absorbing member and a second impact absorbing member having a higher compressive strength than the first impact absorbing member as the impact absorbing member,
The first shock absorbing member is arranged in an annular shape so as to cover the outer peripheral surface of the tip of the lid,
The second shock absorbing member covers the first shock absorbing member from the radially outer side of the cask, and from the side opposite to the side where the lid upper surface region is located along the axial direction of the cask. A cask cushion, which is arranged in an annular shape so as to cover the first shock absorbing member. A cylindrical cask buffer body having a bottomed cylindrical shape, which is provided with an outer shell and a shock absorbing member filled in the outer shell at least around the lid portion of the cask having a substantially cylindrical shape,
The shock absorbing member is
A first impact absorbing member arranged in an annular shape so as to cover the outer peripheral surface of the front end portion of the lid portion, or to cover the outer peripheral surface of the lid portion;
The lid portion is composed of a member having higher compressive strength than the first shock absorbing member, covers the first shock absorbing member from the radially outer side of the cask, and extends along the axial direction of the cask. And a second shock-absorbing member arranged in an annular shape so as to cover the first shock-absorbing member from the side opposite to the upper surface side. In the cask buffer according to claim 1 or 2,
The first shock absorbing member and the second shock absorbing member are formed of members having anisotropy of stress strain characteristics, and a direction having a high stress strain characteristic is perpendicular to the axial direction of the cask. A cask buffer, characterized in that the cask buffer is disposed in a direction. A cylindrical cask buffer body having a bottomed cylindrical shape, which is provided with an outer shell and a shock absorbing member filled in the outer shell at least around the lid portion of the cask having a substantially cylindrical shape,
The region filled with the impact absorbing member is at least
The lid part upper surface area covering the upper surface of the lid part, and the lid outer peripheral surface area covering the outer peripheral surface of the lid part,
In the outer peripheral surface region of the lid portion, a hollow portion that is annularly partitioned so as to cover the outer peripheral surface of the tip portion of the lid portion is formed,
The shock absorbing member filled in the lid outer peripheral surface region covers the cavity from the radially outer side of the cask and has a side with the lid upper surface region along the axial direction of the cask. A cask buffer, which is arranged in an annular shape so as to cover the cavity from the opposite side. The cask buffer according to claim 4, wherein
The shock absorbing member filled in the outer peripheral surface region of the lid is formed of a member having anisotropy of stress strain characteristics, and a direction having a high stress strain characteristic is perpendicular to the axial direction of the cask. A cask buffer, characterized by being arranged in a direction.

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