JP2000193790A - Vessel for transportation and storage of radioactive material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vessel for transportation and storage of radioactive materials which is capable of relatively easily disassembling and simultaneously ensuring the safety as a transportation and storage vessel and taking out gamma ray shield materials and neutron shield material placed in the transportation and storage vessel without the danger of toxic gas generation or damaging it. SOLUTION: In a transportation and storage vessel of radioactive materials provided with a vessel body 1 containing radioactive materials, an outer shell 4 provided by opening a space 10 outside an inner shell 7 of the vessel body 1, radiation shield materials 2 and 3 provided in the space 10 and the lids 5 and 6 of the vessel body 1, the upper part of the outer shell 4 is provided at the vessel body 1 by way of a flange part (upper end plate) 9 and the lower part of it is by way of a lower end plate 11, and at least, the lower end plate 11 is detachably provided by using the bolts at the lower part of the vessel body 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a container for transporting and storing radioactive materials such as spent nuclear fuel.

[0002]

2. Description of the Related Art A container for transporting and storing radioactive materials such as spent nuclear fuel emitted from a nuclear power plant or the like effectively dissipates heat generated when radioactive materials such as spent nuclear fuel stored therein collapse. It is configured to dissipate heat and shield gamma rays and neutrons emitted from radioactive materials, for example, JP-A-7-27896, JP-B 5-39520,
There is one proposed in Japanese Patent Application Laid-Open No. 9-49898.

[0003] The one proposed in JP-A-7-27896 is
A lead layer is provided between the inner shell and the outer shell made of a steel plate, a neutron shielding material is provided outside the outer shell, and a radiating fin is further provided outside the neutron shielding material. The decay heat of the radioactive material generated inside the inner shell is efficiently radiated to the outside by bringing the outer surface into close contact with a thin film of a lead-tin-based solubilizer, and the gamma rays emitted from the radioactive material by the lead layer Are respectively shielded by neutron shielding materials.

[0004] Japanese Patent Publication No. 5-39520 proposes a method in which a side portion that comes into surface contact with the outer peripheral surface of a container body and a radiation portion of the container body are provided between a metal cylindrical container body and an outer cylinder. A plurality of L-shaped metal heat transfer members, each of which has a side extending in the direction, are arranged in the length direction of the container body adjacent to each other in the circumferential direction of the container body. The end is connected to the inner surface of the outer cylinder, and a closed space formed by the heat transfer member and the outer cylinder is filled with a neutron shielding material. In this proposal, a neutron shielding material is also provided on the outer surface of the inner lid.

The one proposed in Japanese Patent Application Laid-Open No. 9-49898 is relatively easy to manufacture and reduces costs compared to the container for transporting and storing radioactive substances proposed in the above-mentioned publication. It has been proposed by the present applicant to increase the storage efficiency of radioactive materials, to have excellent heat transfer performance, and to be able to effectively shield gamma rays and neutrons. Are provided with a gamma ray shielding layer and a neutron shielding layer, and a thermal conductor is provided through the gamma ray shielding layer and the neutron shielding layer. In this proposal, a neutron shielding layer is also provided between the inner lid and the outer lid and between the bottom lid and the bottom outer lid.

[0006]

The conventional containers for transporting and storing radioactive substances as proposed above have not been manufactured from the viewpoint of generally reusing the container material. For this reason, when the transport and storage container is no longer needed, the only option is to discard the container as it is, but the lead used to absorb gamma rays is a harmful substance, and there is a problem in discarding it as it is .

[0007] On the other hand, even if the container for transportation and storage is discarded, container materials such as lead and resin blocks are effective resources and can be reused in the future. Since the container for transport and storage of radioactive materials is not manufactured from the viewpoint of reusing the container material, it is disassembled by fusing etc. with great effort, and between the inner and outer shells, between the inner and outer lids, or between the inner and outer It is necessary to take out a gamma ray shielding material made of a lead block or the like attached between the bottom lids and a neutron shielding material made of a resin block or the like. However, when dismantling is fusing, lead or resin may melt out due to its low melting point or emit harmful gases,
Further, in the case of mechanical cutting, it takes a long time to cut, and there is a possibility that the same problem as melting may occur due to heat generation.

The transport / storage container has a trunnion attached to a side surface of the container main body so that the container can be turned upside down and turned over, or lifted and moved, and further secured during transportation. . In mounting the trunnion, usually, the side surface of the container main body is formed in a concave shape, the tip of the trunnion is formed in a convex shape, and the flange portion is mounted on the side surface of the container main body by bolting. But,
In this mounting structure, by fitting the irregularities,
Although it has the advantage of preventing the shear force generated when handling the container using a trunnion from being applied to the bolt, it is necessary to form the side surface of the container body in a concave shape and still maintain the strength of that part on it In addition, since the radiation shielding material is provided around the trunk, the position where the concave shape is formed in the container body is naturally limited. In addition, it is difficult to form a concave shape in the outer shell with such a structure from the viewpoint of maintaining strength, and therefore, the mounting position of the trunnion is extremely restricted due to these factors, and the degree of freedom in container design is limited. Alternatively, since the radiation shielding material is not provided at the end of the container where the trunnion is attached, a problem such that the radiation dose at the end becomes extremely large arises.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and has as its object to assure the safety as a transport / storage container and to relatively easily disassemble it. It is intended to provide a container for transport and storage of a radioactive substance that can take out a gamma ray shielding material or a neutron shielding material provided in the container without risk of generation of harmful gas and without damaging it, and another object is to provide An object of the present invention is to provide a container for transporting and storing radioactive substances having a structure in which a mounting position of a trunnion can be relatively freely set.

[0010]

In order to achieve the above object, a container for transporting and storing radioactive materials according to the present invention comprises:
A container body for storing a radioactive substance, an outer body provided with a space outside the inner body of the container body, a radiation shielding material provided in the space, and a lid of the container body. In the container for transporting and storing radioactive substances, the outer shell is provided on the container body via the upper end plate at the upper part and the lower part via the lower end plate, and at least the lower end plate is detachably provided at the lower part of the container body by bolts. It is. With such a structure, at least the lower end plate can be removed from the lower portion of the container body by removing the bolt, and the radiation shielding material is extracted from the removed portion without generating any harmful gas and with little damage. be able to. Thereby, the container material as well as the radiation shielding material can be effectively reused. Also, in this case, the radiation shielding material can be more easily taken out by providing the upper end plate detachably with a bolt.

In the above-mentioned container for transporting and storing radioactive substances, the lower end plate is detachably provided on the bottom of the container main body by a bolt, and a radiation shielding material is interposed between the lower end plate and the lower end plate. A bottom lid may be provided. In this case, the bottom cover may be detachably attached with bolts, but may be attached by welding such as spot welding with such strength that it does not fall off, whereby the bottom cover can be easily removed. The lower end plate can be removed in a manner similar to that described above, so that not only the radiation shielding material but also the container material can be effectively reused.

In the above-mentioned container for transporting and storing radioactive substances, the upper end plate may be fixed to the inner body of the container body by welding or integrally formed. Even this way paragraph number

As described in [0009], the radiation shielding material can be extracted from the place where the lower end plate is removed, without generating harmful gas, and with almost no damage,
The container material can be effectively reused based on the radiation shielding material.

In the above-mentioned container for transporting and storing radioactive material, the lid is constituted by a double lid of an inner lid and an outer lid thereon, and both of these double lids are detachable by bolts on the upper surface of the flange portion. It may be provided. Thereby, the double lid can also be easily removed.

Still further, in the above-mentioned container for transporting and storing radioactive substances, the trunnion mounted on the side surface of the container body or the side surface of the outer shell is provided with the mounting surface of the flange portion of the trunnion on the curved surface of the container body or the outer shell. It may be formed in a shape along the curved surface and attached. As a result, the trunnion mounting surface of the container body is not cut into a concave shape as in the related art and does not become thinner, so that the mounting position of the trunnion can be made relatively free and the side surface of the container body or It is not necessary to increase the thickness of the side surface of the outer trunk more than necessary.Especially when the trunnion is provided on the side surface of the outer trunk, the thickness of the outer trunk can be reduced.
The thickness of the radiation shielding material provided inside can be increased, and a container for transporting and storing a radioactive substance having excellent shielding performance can be designed.

In the above-mentioned container for transporting and storing radioactive substances, the trunnion attached to the side surface of the container main body or the side surface of the outer shell has the trunnion attached to the recess at the center of the attachment surface of the flange portion of the trunnion. The attachment surface may be formed in a convex portion and fitted and attached. Thereby, the attachment of the trunnion can be made more secure and the operation and effect of paragraph [0014] can be enjoyed.

[0016]

FIG. 1 is a front view showing a cross section of the right half of a container for transporting and storing radioactive materials according to the present invention.
Is an enlarged explanatory view of a portion X in FIG. 1, and FIG. 3 is an enlarged sectional view taken along the line YY of FIG. In the figure, 1 is a container body, 2 is a gamma ray shielding material, 3 is a neutron shielding material, 4 outer trunk, 5 is an inner lid, and 6 is an outer lid.

The container body 1 is made of steel, and has a bottom portion 8 at the lower end of an inner body 7 and a flange portion 9 at the upper end integrally provided by welding or the like. And, in this example, the inner body 7 has a minimum thickness necessary to function as a sealed container. By setting the required minimum thickness in this manner, the storage efficiency of the radioactive substance is improved, and the weight of the entire transport / storage container is reduced.

The outer shell 4 is made of steel and has an inner diameter larger than the outer diameter of the inner shell 7 by a predetermined amount, and forms a space 10 with the inner shell 7. In this example, a lower end plate 11 is attached to a lower portion of the outer shell 4 by welding 12, and the lower end plate 11 is attached to a periphery of the outer bottom of the bottom 8 of the container body 1 by fixing bolts 13. Is attached to the lower surface of the flange portion 9 by welding 14, so that the outer shell 4 forms a space 10 with the inner shell 7 and is attached to the container body 1.

The gamma ray shielding material 2 is a block made of lead having a thickness necessary for shielding gamma rays, and has a cross-sectional shape which follows the cross-sectional shape of the space 10 near the outer peripheral surface of the inner body 7. At the same time, the length is formed substantially equal to the length of the space 10, and the space 10 is mounted near the outer peripheral surface of the inner body 7.

The neutron shielding material 3 is a resin block having a thickness necessary for shielding neutrons, and has a cross-sectional shape along the cross-sectional shape of the space 10 near the inner peripheral surface of the outer shell 4. It is formed and has a length substantially equal to the length of the space 10 and is mounted between the gamma ray shielding material 2 of the space 10 and the inner peripheral surface of the outer shell 4. In addition, gamma ray shielding material 2
The cross-sectional shape of the neutron shielding material 3 described above is a preferred example. It is not necessary that the cross-sectional shape of the inner shell 7 be close to the outer circumferential surface or the outer shell 4 be close to the inner circumferential surface. The point is that any shape (for example, a trapezoid or the like) that can be mounted in the space 10 in a state where both are overlapped may be used.

The inner lid 5 is made of the same material as that of the container body 1 or made of stainless steel, and is fixed to the upper surface of the flange 9 by bolts so as to seal the opening of the container body 1.

The outer lid 6 serves as a protective cover for accommodating a neutron shielding material 15 made of a resin block. The outer lid 6 is provided on the upper surface of the flange portion 9 with fixing bolts 16 so as to cover the inner lid 5. Can be

Further, in this embodiment, a bottom outer cover (protective bottom) 20 made of a ring material 17, a bottom plate 18, and a neutron shielding material 19 made of a resin block is provided on the outer bottom of the bottom portion 8 of the container body 1.
Is provided. The bottom outer lid 20 has a ring member 17 fixed to the lower surface of the lower end plate 11 by welding 21, accommodates a neutron shielding member 19 inside the ring member 17, and seal-welds 22 a bottom plate 18 to a lower inner periphery. It is composed.

Since the container for transporting and storing radioactive materials according to the present invention is constructed as described above, when the container is discarded, it is disassembled according to the following procedure and the internal radiation shielding material is taken out. When disposing, naturally, the inner lid 5 and the outer lid 6 are removed in advance, and the container body 1 is removed.
The radioactive material contained inside is taken out. Then, the welding 12 between the outer shell 4 and the lower end plate 11 and the seal welding 22 between the ring member 17 and the bottom plate 18 are removed by gouging or the like. The welding amount of the welding 12 and the seal welding 22 is a small amount and can be easily removed by gouging or the like. At that time, the neutron shielding members 3 and 19 may be partially burned, but lead (gamma ray shielding material 2) which generates harmful gas is not affected. : The bottom plate 18 is removed from the ring material 17 and the neutron shielding material 19 inside is taken out. : Remove the fixing bolt 13 attaching the lower end plate 11 to the bottom 8 of the container body 1 and remove the lower end plate 11. : The gamma ray shielding material 2 and the neutron shielding material 3 are taken out from the opening formed by removing the lower end plate 11. Thereafter, if necessary, the outer shell 4 free of radioactive contamination is removed by removing the weld 14 by gouging or the like, or by fusing at an appropriate position. As a result, the amount of radioactively contaminated waste can be reduced, and conversely, it is possible to effectively reuse resources as well as radiation shielding materials such as the gamma ray shielding material 2 and the neutron shielding material 3.

On the other hand, in FIGS. 1 and 3, reference numeral 23 denotes a trunnion attached to the outer peripheral surface of the outer shell 4. The trunnion 23 is formed so that the side of the flange 24 that is in contact with the outer shell 4 is formed along the outer peripheral surface of the outer shell 4, and a bolt hole is formed in the outer periphery of the flange 24. 4 is fixed to the outer peripheral surface. Therefore, the outer shell 4
Trunnion 23 without cutting the trunnion mounting surface
Can be attached, the mounting position of the trunnion can be made relatively free, and it is not necessary to make the outer shell 4 unnecessarily thicker in anticipation of becoming thinner as in the prior art, so that the outer shell 4 can be made thinner. Accordingly, the thickness of the radiation shielding members 2 and 3 provided inside can be increased. As shown in FIG. 4, the mounting of the trunnion 23 is as follows.
A recess 26 is formed in the center of the flange 24 of the trunnion 23 on the side in contact with the outer shell 4, and a projection 27 is formed on the outer peripheral surface of the outer shell 4 serving as a mounting surface of the trunnion 23 by overlay welding or cutting.
May be formed, and the protrusion 27 may be fitted into the recess 26 and fixed to the outer peripheral surface of the outer body 4 by the bolt 25. By doing so, the attachment of the trunnion can be made more secure and the above-mentioned effects can be enjoyed.

In the above-described example, the example in which the lower end plate 11 is attached to the bottom portion 8 of the container body 1 with the fixing bolts 13 has been described. However, the present invention is not limited to this example. If the force is low, only a screw-in type fit may be performed.

Further, in the above-described example, an example in which the upper end of the outer shell 4 is attached to the lower surface of the flange portion 9 of the container body 1 by welding 14 has been described, but for example, as shown in FIG. The lower outer peripheral portion may be formed to have a small diameter, and the small diameter portion 28 may be fitted to the inner periphery of the outer shell 4 and fixed by the fixing bolt 29. By doing so, the outer shell 4 can be easily removed. As shown in FIG. 5, a mounting seat 30 for the inner lid 5 is formed on the inner peripheral side of the upper surface of the flange portion 9, and after the inner lid 5 is mounted on the container body 1, a fixing bolt is formed in a bolt hole formed in the seat.
It may be fixed by 31. Reference numeral 32 denotes a sealing material (silicon or the like).

[0028]

As described above, the container for transporting and storing radioactive materials according to the present invention can be relatively easily disassembled while ensuring the safety of the container for transporting and storing. When disposing of the storage / cumulative container, the gamma ray shielding material and the neutron shielding material provided in the transport / storage container can be taken out by dismantling without danger of generating harmful gas and without damaging the container. Because of such extraction, the gamma ray shielding material and the neutron shielding material can be reused, and the resources can be effectively used.

Further, since the trunnion can be relatively freely mounted, the thickness of the outer shell can be reduced when the trunnion is mounted on the outer shell, and the thickness of the gamma ray shielding material or neutron shielding material can be increased accordingly. In addition, it is possible to design a container for transporting and storing radioactive materials having excellent shielding performance.

[Brief description of the drawings]

FIG. 1 is a front view showing a cross section of the right half of a container for transporting and storing radioactive materials according to the present invention.

FIG. 2 is an enlarged explanatory view of a portion X in FIG. 1;

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

FIG. 4 is an enlarged sectional view of a part Y of another embodiment of the container for transporting and storing radioactive substances of the present invention.

FIG. 5 is a front sectional view of another embodiment of the container for transporting and storing radioactive substances of the present invention.

[Explanation of symbols]

1: Container body 2: Gamma ray shielding layer
3: Neutron shielding layer 4: Outer trunk 5: Inner lid
6: Outer lid 7: Inner trunk 8: Bottom
9: Flange part 10: Space 11: Lower end plate 1
2, 14: welding 13, 16: fixing bolt 15, 19: neutron shielding material 1
7: Ring material 18: Bottom plate 20: Bottom outer lid 2
1: welding 22: seal welding 23: trunnion 2
4: Flange 25: Bolt 26: Recess 2
7: Projection 28: Small diameter part 29, 31: Fixing bolt 3
0: Mounting seat for inner lid 32: Seal material

Claims (6)

[Claims] 1. A container body for storing a radioactive substance, an outer body provided with a space outside the inner body of the container body, a radiation shielding material provided in the space, and a lid of the container body In the container for transport and storage of radioactive material comprising: the outer shell is provided on the container body via the upper end plate at the upper part, the lower part via the lower end plate, at least the lower end plate is bolted to the lower part of the container body A container for transporting and storing a radioactive substance, which is detachably provided. 2. The container for transporting and storing radioactive materials according to claim 1, wherein a lower end plate is detachably provided on a bottom portion of the container main body by a bolt, and further a radiation shielding material is interposed on the bottom portion of the lower end plate. A container for transporting and storing radioactive substances, wherein a bottom lid is provided on the lower surface of the plate. 3. The container for transporting and storing a radioactive substance according to claim 1, wherein the upper end plate is a flange portion of the container body which is welded and fixed or integrally formed on the inner body of the container body. 4. The container for transporting and storing radioactive materials according to claim 3, wherein the lid is constituted by a double lid of an inner lid and an outer lid thereon, and each of the double lids is provided with a bolt on the upper surface of the flange portion. A container for transporting and storing radioactive substances, which is provided so as to be detachable. 5. The container for transporting and storing radioactive materials according to claim 1, wherein the trunnion attached to the side surface of the container body or the side surface of the outer shell has the mounting surface of the flange portion of the trunnion attached to the curved surface of the container body or A container for transporting and storing radioactive materials, which is formed and attached along the curved surface of the outer shell. 6. The container for transporting and storing radioactive materials according to claim 1, wherein the trunnion attached to the side surface of the container main body or the side surface of the outer shell has a recess at the center of the mounting surface of the flange portion of the trunnion. A transport / storage container for a radioactive substance, wherein a mounting surface to which a trunnion is mounted is formed in a convex portion and fitted and fitted.