JP3854417B2 - Container for transport and storage of radioactive materials - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a container for transporting and storing radioactive materials such as spent nuclear fuel.
[0002]
[Prior art]
Containers for transporting and storing radioactive materials such as spent nuclear fuel from nuclear power plants, etc. effectively dissipate heat generated when radioactive materials such as spent nuclear fuel stored in the container collapse, and It is configured to shield gamma rays and neutrons radiated from a substance, and for example, those proposed in Japanese Patent Application Laid-Open No. 7-27896, Japanese Patent Publication No. 5-39520, Japanese Patent Application Laid-Open No. 9-49898, and the like.
[0003]
JP-A-7-27896 proposes that a lead layer is provided between an inner cylinder and an outer cylinder made of steel plates, a neutron shielding material is provided outside the outer cylinder, and a radiating fin is provided outside the neutron shielding material. By disposing the lead layer in close contact with the outer surface of the inner cylinder via a thin film of lead / tin-based solution, it efficiently dissipates the decay heat of radioactive materials generated inside the inner cylinder to the outside. The gamma rays emitted from the radioactive material by the lead layer are shielded by the neutron shielding material.
[0004]
In addition, the one proposed in Japanese Patent Publication No. 5-39520 is extended between the metal cylindrical container body and the outer cylinder in the radial direction of the container body and the side part in surface contact with the outer peripheral surface of the container body. A plurality of L-shaped metal heat transfer members made of side portions are arranged in the length direction of the container body adjacent to each other in the circumferential direction of the container body, and further, end portions of the heat transfer member in the radial direction are arranged. It is constructed by filling the inner space of the outer cylinder and filling the sealed space formed by the heat transfer member and the outer cylinder with a neutron shielding material. In this proposal, a neutron shielding material is also provided on the outer surface of the inner lid.
[0005]
Further, the one proposed in Japanese Patent Application Laid-Open No. 9-49898 is relatively easy to manufacture and less expensive than the radioactive material transport and storage container proposed in the above publication, and the radioactive material. Was proposed by the present applicant as a material that can effectively shield gamma rays and neutrons, and has a high gamma ray shielding between the inner and outer shells made of steel. The neutron shielding layer and the neutron shielding layer are provided, and the thermal good 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]
[Problems to be solved by the invention]
By the way, the conventional container for transporting and storing radioactive materials as proposed above is not manufactured from the viewpoint of generally reusing the container material. For this reason, when transport and storage containers are no longer needed, the only way to dispose of the container is as it is, but the lead used to absorb gamma rays is a hazardous substance and there is a problem in disposing of 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 may be reused in the future. Since the container for transportation and storage is not manufactured from the viewpoint that the container material is reused, it is disassembled by fusing etc. with great effort, and between the inner and outer trunks, between the inner and outer lids, or between the inner and outer bottom lids It is necessary to take out a gamma ray shielding material made of a lead block body or the like, or a neutron shielding material made of a resin block body or the like attached to the housing. However, when fracturing is blown out, lead and resin may melt out due to their low melting point, and may release harmful gases. In mechanical cutting, cutting takes time and heat generation is similar to fusing. May cause problems.
[0008]
Further, a trunnion is attached to the side surface of the container body in order to raise and lie down the container for transportation and storage, or to lift and move the container, and to secure the container during transportation. The trunnion is usually attached by forming the side surface of the container body in a concave shape, and forming the front end of the trunnion in a convex shape, and bolting the flange portion to the side surface of the container body. However, this mounting structure has the advantage of preventing the shearing force generated when the container is handled using the trunnion by fitting the irregularities, but the side surface of the container body is formed in a concave shape. In addition, since it is necessary to maintain the intensity | strength of the site | part on it, in addition to the relationship which provides a radiation shielding material around a trunk | drum, the formation position of the concave shape in a container main body is restricted naturally. Also, it is difficult to form a concave shape in the outer body with such a structure from the viewpoint of maintaining strength. Therefore, the installation position of the trunnion is extremely limited, and the degree of freedom in designing the container is limited. Or since the structure which does not provide a radiation shielding material in the container edge part used as the attachment position of a trunnion, the problem that the radiation dose of the said edge part becomes very large will arise.
[0009]
The present invention has been made in view of the circumstances as described above, and its purpose is to be able to be disassembled relatively easily while ensuring safety as a container for transportation and storage, and within the container for transportation and storage. The purpose of the present invention is to provide a container for transporting and storing radioactive materials that can be removed without risk of generating harmful gases and without damaging the existing gamma ray shielding materials or neutron shielding materials. The present invention provides a container for transporting and storing a radioactive substance having a structure that can be relatively freely positioned.
[0010]
[Means for Solving the Problems]
In order to achieve the above-mentioned object, the invention according to claim 1 includes a container main body for containing a radioactive substance, an outer cylinder provided by opening a space outside the inner cylinder of the container main body, and a container provided in the space. and radiation shielding material that is, in the transport and storage container for radioactive material and a cover of the container body, the outer cylinders, the upper end plate, provided on the container body through the bottom plate of the lower and the upper portion thereof, wherein The lower end plate is provided at the lower part of the container body so as to be removable by a bolt and an opening through which the radiation shielding material can be taken out from the space by loosening the bolt and removing it from the container body . It is characterized by . Because it is such a structure, the bolt bottom plate can be removed from the bottom of the container body by removing, without generating harmful gases radiation shielding material from an opening made by removing the lower end plate, It can also be extracted with little damage. Thereby, the container material can be effectively reused as well as the radiation shielding material. In this case, the radiation shielding material can be easily taken out by providing the upper end plate so as to be removable by the bolt.
[0011]
The invention of claim 2, Te transport and storage vessel odor of radioactive material according to claim 1, which is characterized in that the bottom lid is provided on the lower surface of the lower plate by interposing a radiation shielding material It is. In this case, the bottom cover may be removably attached with a bolt, but it may be attached by welding such as spot welding with a strength that does not drop off, so that the bottom cover can be easily removed, and then the above In this manner, the lower end plate can be removed, and the container material as well as the radiation shielding material can be effectively reused as described above.
[0012]
A third aspect of the present invention, Te transport and storage vessel odor of radioactive material according to claim 1 or 2, wherein the upper plate is a welded or container body are formed integrally on the inner cylinder of the container body It is formed as a flange part, and the outer body is fitted to a small diameter part formed on the inner periphery of the upper part at the lower outer peripheral part of the flange part, and is fixed to the flange part so as to be removable by a fixing bolt. It is characterized by. Even in this way, as described in paragraph [0009], the radiation shielding material can be extracted from the opening made by removing the lower end plate without generating harmful gas and almost without damaging it. The container material can be effectively reused as well as the shielding material. Moreover, when removing an outer cylinder as needed, an outer cylinder can be easily removed from a container main body.
[0013]
The invention according to claim 4, Te transport and storage vessel odor of radioactive material according to claim 3, with is composed of double lid of the outer lid thereon the lid and the inner lid, even these double lid are both the flange It is characterized in that it is detachably provided on the upper surface of the part with bolts . Thereby, a double lid can also be removed easily.
[0014]
The invention of claim 5, wherein the Te transport and storage vessel odor of radioactive material according to claim 1, sides or trunnion mounted to the side of the outer cylinder of the container body, the mounting surface of the flange portion of the trunnion It is formed and attached in a shape along the curved surface of the container main body or the curved surface of the outer body . This prevents the trunnion mounting surface of the container body from being cut into a concave shape and thinning as in the prior art, so that the trunnion mounting position can be made relatively free, and in anticipation of thinning, the side surface of the container body or It is no longer necessary to increase the thickness of the side of the outer cylinder more than necessary. Especially when the trunnion is provided on the side of the outer cylinder, the thickness of the outer cylinder can be reduced, so that the thickness of the radiation shielding material provided on the inside is increased accordingly. In addition, it is possible to design a container for transporting and storing radioactive materials with excellent shielding performance.
[0015]
The invention of claim 6, Te transport and storage vessel odor of radioactive material according to claim 1, sides or trunnion mounted to the side of the outer cylinder of the container body, the mounting surface central portion of the flange portion of the trunnion Is attached to the recess by fitting the mounting surface on which the trunnion is attached to the projection . As a result, the trunnion can be attached more safely and the effect of paragraph number [0014] can be enjoyed.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a front view showing the right half of the container for transporting and storing radioactive materials according to the present invention in cross section, FIG. 2 is an enlarged explanatory view of a portion X in FIG. 1, and FIG. 3 is an enlarged view of YY in FIG. It is sectional drawing. In the figure, 1 is a container main body, 2 is a gamma ray shielding material, 3 is a neutron shielding material, 4 outer cylinder, 5 is an inner lid, and 6 is an outer lid.
[0017]
The container main body 1 is made of steel, and is configured by integrally providing a bottom portion 8 at the lower end of the inner body 7 and a flange portion 9 at the upper end by welding or the like. In this example, the inner cylinder 7 has a minimum thickness necessary for functioning as a sealed container. Thus, by setting it as the minimum thickness required, the storage efficiency of a radioactive substance is improved, and weight reduction of the whole container for transportation and storage is achieved.
[0018]
The outer cylinder 4 is made of steel and has an inner diameter that is larger than the outer diameter of the inner cylinder 7 by a predetermined amount, and forms a space 10 between the outer cylinder 4 and the inner cylinder 7. In this example, the lower end plate 11 is attached to the lower portion of the outer cylinder 4 by welding 12, and the lower end plate 11 is attached to the outer bottom peripheral portion of the bottom portion 8 of the container body 1 by the fixing bolt 13, and the outer cylinder 4 Is attached to the lower surface of the flange portion 9 by welding 14 so that the outer cylinder 4 is attached to the container body 1 with a space 10 formed between the outer cylinder 4 and the inner cylinder 7.
[0019]
The gamma ray shielding material 2 is a lead block having a thickness necessary for shielding gamma rays, and its cross-sectional shape is formed in a shape that conforms to the cross-sectional shape near the outer peripheral surface of the inner body 7 of the space 10. The length is substantially equal to the length of the space 10 and is mounted near the outer peripheral surface of the inner cylinder 7 of the space 10.
[0020]
The neutron shielding material 3 is a resin block having a thickness necessary for shielding neutrons, and the cross-sectional shape thereof is formed along the cross-sectional shape of the space 10 near the inner peripheral surface of the outer body 4. In addition, the length of the space 10 is substantially equal to the length of the space 10, and the space 10 is mounted between the gamma ray shielding member 2 and the inner peripheral surface of the outer body 4. The cross-sectional shapes of the gamma ray shielding material 2 and the neutron shielding material 3 have been described as preferred examples. The cross-sectional shape near the outer peripheral surface of the inner cylinder 7 or the cross-sectional shape near the inner peripheral surface of the outer cylinder 4 is used. The shape does not need to be along, and may be any shape that can be mounted in the space 10 in a state where they overlap each other (for example, a trapezoid).
[0021]
The inner lid 5 is made of the same material as the container main body 1 or made of stainless steel, and is fixed to the upper surface of the flange portion 9 with bolts so as to seal the opening of the container main body 1.
[0022]
The outer lid 6 serves as a protective cover containing a neutron shielding material 15 made of a resin block, and is provided on the upper surface of the flange portion 9 by a fixing bolt 16 so as to cover the inner lid 5.
[0023]
Further, in this example, a bottom outer lid (protective bottom) 20 comprising a ring material 17, a bottom plate 18 and a neutron shielding material 19 comprising a resin block body is provided on the outer bottom of the bottom portion 8 of the container body 1. Yes. 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 material 19 inside the ring member 17, and seal welds the bottom plate 18 to the lower inner periphery. Configured.
[0024]
Since the container for transporting and storing radioactive material according to the present invention is configured as described above, when the container is discarded, it is disassembled by the following procedure and the internal radiation shielding material is taken out. In addition, when discarding, of course, the inner lid 5 and the outer lid 6 are removed beforehand, and the radioactive substance accommodated in the container main body 1 is taken out. Then, (1): welding 12 between the outer body 4 and the lower end plate 11 and seal welding 22 between the ring material 17 and the bottom plate 18 are removed by gouging or the like. The welding amount of the weld 12 and the seal weld 22 is very small and can be easily removed by gouging or the like. At that time, the neutron shielding materials 3 and 19 may be partially burned, but lead (gamma ray shielding material 2) that generates harmful gas is not affected.
{Circle around (2)} The bottom plate 18 is removed from the ring material 17 and the internal neutron shielding material 19 is taken out.
{Circle around (3)} The fixing bolt 13 that fixes the lower end plate 11 to the bottom 8 of the container body 1 is removed, and the lower end plate 11 is removed.
{Circle around (4)} 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.
{Circle around (5)} After that, if necessary, for example, the outer body 4 free from radioactive contamination is removed by welding 14 from the welding 14 or by fusing at an appropriate position. As a result, the amount of radioactively contaminated waste can be reduced, and conversely, not only the radiation shielding materials such as the gamma ray shielding material 2 and the neutron shielding material 3 but also the reuse of resources can be effectively achieved.
[0025]
On the other hand, in FIGS. 1 and 3, reference numeral 23 denotes a trunnion attached to the outer peripheral surface of the outer body 4. The trunnion 23 is formed such that the side of the flange 24 that contacts the outer cylinder 4 is formed along the outer peripheral surface of the outer cylinder 4, and a bolt hole is formed in the outer peripheral part of the flange 24. 4 is fixed to the outer peripheral surface. Accordingly, since the trunnion 23 can be mounted without cutting the trunnion mounting surface of the outer cylinder 4, the mounting position of the trunnion can be made relatively free, and the thickness of the outer cylinder 4 is required in anticipation of being thinner as before. Since it is not necessary to make it thicker and the thickness of the outer body 4 can be reduced, the thickness of the radiation shielding materials 2 and 3 provided on the inner side can be increased accordingly. As shown in FIG. 4, the trunnion 23 is attached by forming a recess 26 in the center of the trunnion 23 on the side in contact with the outer cylinder 4 of the flange 24, so that the trunnion 23 is attached to the outer cylinder 4. The protrusion 27 may be formed on the outer peripheral surface by build-up welding or cutting, and the protrusion 27 may be fitted into the recess 26 and fixed to the outer peripheral surface of the outer body 4 with the bolt 25. By doing in this way, trunnion attachment can be made safer and the said effect can be enjoyed.
[0026]
In the above example, the example in which the lower end plate 11 is attached to the bottom 8 of the container body 1 with the fixing bolt 13 has been described. However, the present invention is not limited to this example, and for example, the force applied to this portion is small. In some cases, it is only necessary to perform screw-in fitting.
[0027]
In the above example, the outer cylinder 4 is attached to the lower surface of the flange portion 9 of the container body 1 by welding 14 at the upper end. However, as shown in FIG. May be formed into a small diameter, and the small diameter portion 28 may be fitted to the inner periphery of the outer body 4 and fixed by a fixing bolt 29. By doing in this way, the outer cylinder 4 can be removed easily. Further, 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 attached to the container body 1, a bolt is formed in the bolt hole formed in the seat. It may be fixed by 31. Reference numeral 32 denotes a sealing material (silicon or the like).
[0028]
【The invention's effect】
As described above, the transport and storage container for radioactive substances according to the present invention can be disassembled relatively easily while ensuring safety as a transport and storage container. When discarding, gamma ray shielding materials and neutron shielding materials provided in the container for transportation and storage can be taken out without risk of damaging gas generation and without being damaged. Therefore, these gamma ray shielding materials and neutron shielding materials can be reused and resources can be used effectively.
[0029]
In addition, the trunnion can be mounted in a relatively free position, so that the thickness of the outer shell can be reduced when mounting to the outer shell, and the thickness of the gamma ray shielding material and neutron shielding material can be increased accordingly. This makes it possible to design a container for transporting and storing radioactive materials that is superior to other materials.
[Brief description of the drawings]
FIG. 1 is a front view showing, in section, the right half of a radioactive material transport and storage container according to the present invention.
FIG. 2 is an enlarged explanatory view of a portion X in FIG. 1;
FIG. 3 is an enlarged YY sectional view of FIG. 1;
FIG. 4 is an enlarged cross-sectional view of a Y portion of another embodiment of the radioactive substance transport / storage container according to the present invention.
FIG. 5 is a front sectional view of another embodiment of the container for transporting and storing radioactive material of the present invention.
[Explanation of symbols]
1: Container body 2: Gamma ray shielding material 3: Neutron shielding material 4: Outer trunk 5: Inner lid 6: Outer lid 7: Inner trunk 8: Bottom part 9: Flange part 10: Space 11: Lower end plate 12, 14: Welding 13 , 16: Fixing bolt 15, 19: Neutron shielding material 17: Ring material 18: Bottom plate 20: Bottom outer lid 21: Welding 22: Seal welding 23: Trunnion 24: Flange 25: Bolt 26: Recess 27: Protrusion 28: Small diameter part 29, 31: Fixing bolt 30: Inner lid mounting seat 32: Sealing material

Claims (6)

A container body for containing the radioactive material, and an outer cylinder that is provided with a space outside of the inner cylinder of the container body, the radiation shielding material provided in the space, radioactive with a lid of the container body in the transport and storage container for material, the outer cylinders, the upper the upper plate, provided on the container body through the bottom plate of the lower, the lower end plate, removably by bolts at the bottom of the container body, and transport and storage container for radioactive material, characterized in that it said provided to allow openings may retrieve the radiation shielding material from the space by detaching from the container body by loosening the bolts. In the transport and storage container for radioactive material according to claim 1, the transport and storage container for radioactive material, characterized in that the bottom lid is provided on the lower surface of the lower plate by interposing a radiation shielding material. The upper plate is formed as a flange portion of the welded or container body are formed integrally on the inner cylinder of the container body, the outer cylinders, forming an inner periphery of the upper to the lower outer peripheral portion of the flange portion The radioactive substance transport and storage container according to claim 1 or 2, wherein the container is fitted to the small-diameter portion and is detachably fixed to the flange portion by a fixing bolt . In the transport and storage container for radioactive material according to claim 3, with is composed of double lid of the outer lid thereon the lid and the inner lid, removable by bolts to the upper surface of even these double lid are both the flange portion A container for transporting and storing radioactive materials, characterized in that it is provided in the container. In the transport and storage container for radioactive material according to claim 1, sides or trunnion mounted to the side of the outer cylinder of the container body, the mounting surface of the flange portion of the trunnion of the curved or outer body of the container body A container for transporting and storing a radioactive substance, wherein the container is formed and attached in a shape along a curved surface. 2. The container for transporting and storing radioactive material according to claim 1, wherein the trunnion attached to the side surface of the container body or the side surface of the outer body is attached to the concave portion at the center of the mounting surface of the flange portion of the trunnion. A container for transporting and storing a radioactive substance, wherein a surface to be attached is formed in a convex portion and fitted together.

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