Radioactive material storage container

Abstract

In radioactive material storage containers, the deterioration of components is suppressed by lowering the temperature. [Solution] The cask comprises a cask body having a cavity inside and an opening on one side in the axial direction, a lid that can open and close the opening of the cask body, and an insulating layer disposed on at least one of the bottom of the cask body and the lid.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a radioactive material storage container that houses radioactive waste.

BACKGROUND ART

[0002] At nuclear facilities, radioactive waste such as spent fuel generated in nuclear reactors and the like is stored in radioactive material storage containers, transported to storage facilities, reprocessing facilities and the like, and then stored or reprocessed. The radioactive material storage container is composed of a cask main body having a bottomed cylindrical shape with an open top, and a lid part fixed to the top of the cask main body to close the opening. The radioactive material storage container is provided with shock absorbers during transportation and storage. The shock absorber is attached to the axial end of the radioactive material storage container. The shock absorber absorbs impact by deforming when the radioactive material storage container is dropped, tipped over, or collided.

[0003] Examples of the radioactive material storage container fitted with a shock absorber include those described in Patent Document 1.

PRIOR ART DOCUMENTS

PATENT DOCUMENTS

[0004]

PATENT DOCUMENT 1

SUMMARY OF THE INVENTION

PROBLEMS TO BE SOLVED BY THE INVENTION

[0005] Buffers are generally constructed by covering a buffer material, such as wood, with metal plates. Depending on the materials used and the environment in which they are used, buffers can deteriorate over time. Specifically, because radioactive material containers contain radioactive waste, they become hot, and heat is transferred from the container to the buffer, causing its temperature to rise and potentially accelerating its deterioration. In addition, components such as resin are placed on the outside of the cavity of the radioactive material container as neutron shielding. Since components such as resin have limitations on their operating temperature, it is necessary to reduce the temperature of the radioactive material container.

[0006] This disclosure aims to solve the aforementioned problems and to provide a radioactive material storage container that suppresses the deterioration of its components by lowering the temperature. [Means for solving the problem]

[0007] To achieve the above objectives, the radioactive material storage container of this disclosure comprises a cask body having a cavity inside and an opening on one side in the axial direction, a lid that can open and close the opening of the cask body, and an insulating layer disposed on at least one of the bottom of the cask body and the lid. [Effects of the Invention]

[0008] According to the radioactive material storage container of this disclosure, the deterioration of the constituent materials can be suppressed by lowering the temperature. [Brief explanation of the drawing]

[0009] [Figure 1] Figure 1 is a partially cutaway schematic diagram showing the internal structure of a radioactive material storage container. [Figure 2] Figure 2 is a cross-sectional view of the radioactive material storage container along its radial direction. [Figure 3] Figure 3 is a front view showing a radioactive material storage container with a buffer attached in a horizontal position. [Figure 4] Figure 4 is a cross-sectional view showing a radioactive material storage container according to the first embodiment. [Figure 5] Figure 5 is a cross-sectional view showing a radioactive material storage container according to the second embodiment. [Figure 6] Figure 6 is a cross-sectional view showing a radioactive material storage container according to the third embodiment. [Modes for carrying out the invention]

[0010] Preferred embodiments of the present disclosure will be described in detail below with reference to the drawings. However, these embodiments do not limit the present disclosure, and where there are multiple embodiments, they may be combinations of these embodiments. Furthermore, the components in the embodiments include those readily conceivable by those skilled in the art, those that are substantially identical, and those that are equivalent.

[0011] [First Embodiment] <Radioactive material storage container> Figure 1 is a partially cutaway schematic diagram showing the internal structure of a radioactive material storage container, and Figure 2 is a cross-sectional view along the radial direction of the radioactive material storage container.

[0012] As shown in Figures 1 and 2, the cask 11, as a radioactive material storage container, comprises a cask body 12 and a lid 13. The cask body 12 has a body shell 21. The body shell 21 is cylindrical (in this embodiment, cylindrical in shape), with an opening 22 at its upper end and a closed lower end. The body shell 21 has a cavity 23 inside, and a basket 24 is placed in the cavity 23. The basket 24 is provided with a plurality of cells (storage compartments) 25 capable of individually storing radioactive materials (e.g., spent fuel assemblies). The body shell 21 is a forged product of carbon steel having a gamma-ray shielding function. However, stainless steel may be used instead of carbon steel for the body shell 21. Alternatively, the body shell 21 may be a casting of spheroidal graphite cast iron or carbon steel cast steel.

[0013] The cask body 12 has an outer cylinder 26 positioned on the outer circumferential surface of the main body shell 21 with a gap between them. Multiple copper heat transfer fins 27 are provided circumferentially spaced between the outer circumferential surface of the main body shell 21 and the inner circumferential surface of the outer cylinder 26 to conduct heat. In the space enclosed by the main body shell 21, the outer cylinder 26, and the heat transfer fins 27, a resin 28 is placed as a neutron shield. The resin 28 is a polymer material containing a large amount of hydrogen and contains boron or a boron compound having a neutron shielding function.

[0014] The cask body 12 is provided with a bottom portion 29 that protrudes below the closed lower end of the main body shell 21. The bottom portion 29 has a space enclosed by the closed lower end of the main body shell 21, and resin (neutron shield) 34 is placed in this space.

[0015] The cask body 12 has trunnions 30 for lifting the cask 11 provided on the body shell 21 at 90-degree or 180-degree intervals on the upper and lower parts of the cask 11. The trunnions 30 are provided from the body shell 21 through the outer cylinder 26. The trunnions 30 protrude to the outermost part of the cask 11.

[0016] The lid portion 13 is positioned in the opening 22 of the main body 21. The lid portion 13 closes the opening 22 and seals the main body 21 (cask body 12). The lid portion 13 has a primary lid 31, a secondary lid 32, and a tertiary lid 33. The primary lid 31 is formed in a disc shape from carbon steel or stainless steel that shields against gamma rays. The secondary lid 32 covers the primary lid 31 and is visible on the outside of the cask 11, and like the primary lid 31, is formed in a disc shape from carbon steel or stainless steel that shields against gamma rays. A resin (neutron shield) 35 is provided between the primary lid 31 and the secondary lid 32. The tertiary lid 33 is provided on the outside of the secondary lid 32, but the tertiary lid 33 may be omitted. The tertiary lid 33 is formed in a disc shape from carbon steel or stainless steel that shields against gamma rays, similar to the primary lid 31 and the secondary lid 32.

[0017] The primary lid 31 is fixed to a first step portion 22a formed in the opening 22 of the main body cylinder 21 by bolts (not shown) made of carbon steel or stainless steel. The secondary lid 32 is fixed to a second step portion 22b formed in the opening 22 of the main body cylinder 21 by bolts (not shown) made of carbon steel or stainless steel. Although not shown, metal gaskets are provided between the primary lid 31 and the first step portion 22a, and between the secondary lid 32 and the second step portion 22b. The metal gaskets ensure sealing performance between the primary lid 31 and the first step portion 22a, and between the secondary lid 32 and the second step portion 22b. The tertiary lid 33 is fixed to a third step portion 22c formed in the opening 22 of the main body cylinder 21 by bolts (not shown) made of carbon steel or stainless steel. A rubber O-ring is provided between the tertiary lid 33 and the main body cylinder 21 to ensure sealing performance.

[0018] In a nuclear power generation facility, for example, a plurality of spent fuel assemblies are stored in each cell 25 of the basket 24 of the main body cylinder 21 of the cask 11, and the cask is hermetically sealed by the lid portion 13. The cask 11 is transported, for example, from the nuclear power generation facility to a storage facility. During transportation, the cask 11 is fitted with transportation buffers (not shown). The transportation buffers are fitted to the upper portion and the lower portion of the cask main body 12. The cask 11 is mounted in a horizontally laid state on the loading platform of a transportation vehicle and transported to the storage facility. During storage, the cask 11 may be placed horizontally with buffers, placed vertically without buffers, or placed vertically with buffers, among other configurations.

[0019] <Arrangement of radioactive material storage container> Figure 3 is a front view showing the horizontally placed state of the radioactive material storage container fitted with buffers.

[0020] As shown in Figure 3, buffers 41 and 42 can be fitted to the axial ends of the cask 11. The buffer 41 is fitted to the bottom portion 29 of the cask main body 12, which is one axial end of the cask 11, and the buffer 42 is fitted to the lid portion 13, which is the other axial end of the cask 11.

[0021] In a nuclear power plant, for example, spent fuel assemblies are stored in the cells 25 (see Figure 1) of the basket 24 of the main body shell 21 of the cask 11, and sealed by the lid 13. The cask 11 is transported, for example, from the nuclear power plant to a storage facility. A transport buffer (not shown) is attached to the cask 11 during transport. When the cask 11 is transported to the storage facility, the transport buffer is removed, a buffer 41 is attached to the bottom 29 of the cask body 12, and a buffer 42 is attached to the lid 13. Alternatively, the cask may be transported with buffer 41 attached instead of the transport buffer. The buffers 41 and 42 are transport buffers, but they may also be storage buffers.

[0022] The cask 11 is stored in a horizontal position with its central axis O aligned horizontally, with the cushioning bodies 41 and 42 attached. The cask 11 is supported on a stand 43 in a horizontal position. The stand 43 is provided with a plurality of support parts 44, and the cask 11 is supported, for example, by each trunnion 30 on a support part 44. The cask 11 is stored in a horizontal position with its central axis O aligned horizontally by the stand 43. In this case, the cask 11 has the cushioning body 41 attached to one side along the central axis O (bottom 29 side) and the cushioning body 42 attached to the other side along the central axis O (lid 13 side). The cushioning bodies 41 and 42 have substantially the same configuration.

[0023] The cask 11 may also be stored in a vertical position with its central axis O aligned vertically. In this case, the cask 11 is placed vertically with its lid 13 facing upwards, and a buffer 42 is attached to the lid 13 side. When stored, the cask 11 is fitted into a frame (not shown) at its bottom 29, or fixed to a frame by securing the trunnion, and stored in a vertical position with its central axis O aligned vertically.

[0024] <Internal structure of a radioactive material storage container> Figure 4 is a cross-sectional view showing a radioactive material storage container according to the first embodiment.

[0025] As shown in Figure 4, the cask 11 comprises a cask body 12 and a lid 13. The cask body 12 has a body shell 21, which has a cavity 23 inside, and a basket 24 is placed in the cavity 23. The body shell 21 also has an outer cylinder 26 arranged on its outer surface via a resin 28 acting as a neutron shield. The cask body 12 has an opening 22 formed on one side in the axial direction, and a bottom 29 provided on the other side in the axial direction to close it. The bottom 29 is provided with a resin 34 acting as a neutron shield. The lid 13, on the other hand, can open and close the opening 22 of the body shell 21. The lid 13 has a primary lid 31 and a secondary lid 32. A resin 35 acting as a neutron shield is provided between the primary lid 31 and the secondary lid 32.

[0026] The cask body 12 has an insulating layer 51 at its bottom 29. The cask body 12 has resin 34 placed at its bottom 29, and the insulating layer 51 is positioned inside the resin 34 at the bottom 29. That is, the insulating layer 51 is positioned between the cavity 23 and the resin 34.

[0027] The resin 34 is placed inside the bottom 29, that is, in the thick part of the bottom 29 in the cask body 12. The resin 34 is disc-shaped and its periphery is demarcated by the metal material that makes up the bottom 29. The heat insulating layer 51 is placed inside the bottom 29, that is, in the thick part of the bottom 29 in the cask body 12. The heat insulating layer 51 is disc-shaped, similar to the resin 34, and its periphery is demarcated by the metal material that makes up the bottom 29. The heat insulating layer 51 is placed between the cavity 23 and the resin 34. It is preferable that the outer diameter of the heat insulating layer 51 is larger than the outer diameter of the resin 34, but it is still effective even if it is smaller.

[0028] The thermal insulation layer 51 is a hollow portion 52. The hollow portion 52 is partitioned by a metal member. That is, the hollow portion 52 is a hollow disc member formed from a metal plate 53. The thermal insulation layer 51 is filled with air in the hollow portion 52. However, the thermal insulation layer 51 may have a vacuum in the hollow portion 52. The thermal insulation layer 51 may also have an inert gas (for example, nitrogen gas or argon gas) or foamed resin filled in the hollow portion 52. Furthermore, the hollow portion 52 may be formed from a different material, such as foamed resin (with high thermal insulation properties), instead of a metal plate 53.

[0029] <Function of radioactive material storage containers> Cask 11 has a buffer 41 attached to its bottom 29 and a buffer 42 attached to its lid 13, and is stored in a horizontal position. Since radioactive waste is stored in the cavity 23 of Cask 11, the heat from the radioactive waste is transferred to the cask body 12, causing its temperature to rise. In this case, the heat from Cask 11 is transferred to the buffers 41, 42 and resins 34, 35, causing the buffers 41, 42 and resins 34, 35 to rise in temperature and potentially degrade.

[0030] Cask 11 has an insulating layer 51 at the bottom 29 of the cask body 12. The heat of the radioactive waste stored in the cavity 23 of the cask body 12 is blocked by the insulating layer 51. Since the insulating layer 51 is positioned between the cavity 23 and the resin 34, the heat of the radioactive waste is blocked by the insulating layer 51 and its transfer to the resin 34 is suppressed. The heat blocked by the insulating layer 51 is transferred to the radially outward side of the cask body 12 and released to the outside from the outer periphery of the cask body 12.

[0031] Therefore, the temperature rise of the resin 34 is suppressed, and the degradation of the resin 34 is suppressed. In addition, the heat of the radioactive waste is blocked by the insulating layer 51 and is not transferred to the resin 34 but is released to the outside from the outer circumference of the cask body 12, so the temperature rise of the buffer 41 is suppressed, and the degradation of the buffer 41 is suppressed.

[0032] In the first embodiment, the heat insulating layer 51 was made into a hollow portion 52 and a hollow disc member formed from a metal plate 53, but the configuration is not limited to this. The heat insulating layer 51 may also be a space directly formed inside the bottom 29 of the cask body 12. Furthermore, although the heat insulating layer 51 was placed between the cavity 23 and the resin 34 with a gap so as not to contact the cavity 23 or the resin 34, the heat insulating layer 51 may also be placed away from the cavity 23 and in contact with the resin 34.

[0033] [Second Embodiment] Figure 5 is a cross-sectional view showing a radioactive material storage container according to the second embodiment. Components having the same function as those in the first embodiment described above are denoted by the same reference numerals, and detailed descriptions are omitted.

[0034] The cask body 12 has an insulating layer 51 at its bottom 29. The insulating layer 51 is positioned inside the resin 34 at the bottom 29. The insulating layer 51 is located inside the bottom 29, that is, in the thicker part of the bottom 29 of the cask body 12. The insulating layer 51 is a hollow section 52. The hollow section 52 is a hollow disc member formed from a metal plate 53.

[0035] The cask body 12 has multiple fins (heat dissipation parts) 61, 62 on the outer circumference of the outer side of the heat insulating layer 51. The fins 61 are, for example, ring-shaped and are provided on the outer circumference of the bottom 29 of the cask body 12. A buffer 41 is attached to the bottom 29 of the cask 11, and the fins 61 can contact the buffer 41. The fins 62 are, for example, ring-shaped and are provided on the outer circumference of the outer cylinder 26 of the cask body 12. Multiple fins 62 are arranged on the bottom 29 side of the cask body 12, spaced apart in the axial direction.

[0036] Furthermore, the fins 61 and 62 are not limited to a ring shape. For example, the fins 61 and 62 may be plate members oriented along the axial direction, and multiple fins may be provided spaced apart in the circumferential direction.

[0037] Cask 11 has an insulating layer 51 at the bottom 29 of the cask body 12. The heat of the radioactive waste stored in the cavity 23 of the cask body 12 is blocked by the insulating layer 51. Since the insulating layer 51 is positioned between the cavity 23 and the resin 34, the heat of the radioactive waste is blocked by the insulating layer 51 and its transfer to the resin 34 is suppressed. The heat blocked by the insulating layer 51 is transferred to the radially outward side of the cask body 12 and released to the outside through a plurality of fins 61, 62 provided on the outer circumference of the cask body 12.

[0038] Therefore, the temperature rise of the resin 34 is suppressed, and the degradation of the resin 34 is suppressed. In addition, the heat of the radioactive waste is blocked by the insulating layer 51 and is not transferred to the resin 34 but is released to the outside from the outer circumference of the cask body 12, so the temperature rise of the buffer 41 is suppressed, and the degradation of the buffer 41 is suppressed.

[0039] [Third Embodiment] Figure 6 is a cross-sectional view showing a radioactive material storage container according to the third embodiment. Components having the same function as those in the first embodiment described above are denoted by the same reference numerals, and detailed descriptions are omitted.

[0040] As shown in Figure 6, the cask 11 comprises a cask body 12 and a lid 13. The cask body 12 has an opening 22 formed on one side in the axial direction and is closed off by a bottom 29 on the other side in the axial direction. The lid 13 has a primary lid 31 and a secondary lid 32. A resin 35 acting as a neutron shield is provided between the primary lid 31 and the secondary lid 32.

[0041] The lid portion 13 is provided with an insulating layer 71. The lid portion 13 has resin 35 inside, and the insulating layer 71 is positioned inside the resin 35 in the lid portion 13. That is, the insulating layer 71 is positioned between the cavity 23 and the resin 35. The lid portion 13 has a primary lid 31 and a secondary lid 32, with resin 35 positioned between the primary lid 31 and the secondary lid 32, and the insulating layer 71 is positioned between the primary lid 31 and the resin 35.

[0042] The resin 35 is placed between the primary lid 31 and the secondary lid 32 and fixed to the primary lid 31. The resin 35 is disc-shaped and its periphery is partitioned by the metal material that constitutes the primary lid 31. The heat insulating layer 71 is disc-shaped, similar to the resin 35, and its periphery is partitioned by the metal material that constitutes the primary lid 31. The heat insulating layer 71 is a hollow portion 72, similar to the heat insulating layer 51, and may be a hollow disc member formed from a metal plate. The heat insulating layer 71 has air filling the hollow portion 72. However, the heat insulating layer 71 may have a vacuum in the hollow portion 72. Alternatively, the heat insulating layer 71 may have an inert gas (for example, nitrogen gas or argon gas) filling the hollow portion 72. The configuration of the hollow portion 72 may be the same as that of the hollow portion 52 described above.

[0043] Furthermore, the cask 11 has a primary lid 31 fixed to the opening 22 of the cask body 12. A metal gasket 81 is placed between the first stage portion 22a of the opening 22 and the primary lid 31. The metal gasket 81 ensures airtightness between the primary lid 31 and the first stage portion 22a. In this case, the first stage portion 22a becomes the seat surface of the metal gasket 81, and a low thermal conductivity member 82 is provided on the seat surface. The low thermal conductivity member 82 is, for example, a build-up weld made using stainless steel (SUS) as the welding material. The cask body 12 has the primary lid 31 fixed with the metal gasket 81 placed on the low thermal conductivity member 82 of the first stage portion 22a. Note that the low thermal conductivity member 82 is not limited to this configuration. The low thermal conductivity member 82 may be provided on the primary lid 31 side, or it may be configured to cover the entire outside of the metal gasket 81, for example, as shown by the dashed line in Figure 6.

[0044] The cask 11 has an insulating layer 71 on the primary lid 31 of the lid portion 13. The heat of the radioactive waste stored in the cavity 23 of the cask body 12 is blocked by the insulating layer 71. Since the insulating layer 71 is positioned between the cavity 23 and the resin 35, the heat of the radioactive waste is blocked by the insulating layer 71 and its transfer to the resin 35 is suppressed. The heat blocked by the insulating layer 71 is transferred to the radially outward side of the primary lid 31 and released to the outside from the outer circumference of the cask body 12.

[0045] Therefore, the temperature rise of the resin 35 is suppressed, and the degradation of the resin 35 is suppressed. In addition, the heat of the radioactive waste is blocked by the insulating layer 71 and is not transferred to the resin 35 but is released to the outside from the outer circumference of the cask body 12, so the temperature rise of the buffer 42 is suppressed, and the degradation of the buffer 42 is suppressed.

[0046] Furthermore, the cask body 12 is provided with a low thermal conductivity member 82 at the first stage portion 22a of the opening, and the primary lid 31 is fixed with the metal gasket 81 placed on the low thermal conductivity member 82. As a result, since the low thermal conductivity member 82 has lower thermal conductivity than the cask body 12 and the primary lid 31, the heat from the radioactive waste is less likely to be transferred to the metal gasket 81, the temperature rise of the metal gasket 81 is suppressed, and the deterioration of the metal gasket 81 is suppressed.

[0047] [Effects of this embodiment] The radioactive material storage container according to the first embodiment comprises a cask body 12 having a cavity 23 and an opening 22 on one side in the axial direction, a lid 13 that can open and close the opening 22 of the cask body 12, and insulating layers 51, 71 disposed on at least one of the bottom 29 of the cask body 12 and the lid 13.

[0048] According to the first embodiment of the radioactive material storage container, the cask 11 stores high-temperature radioactive waste in the cavity 23, causing the heat from the radioactive waste to be transferred to the cask body 12 and lid 13, resulting in a temperature increase. However, since the cask body 12 and lid 13 are provided with insulating layers 51 and 71, the transfer of heat is blocked. As a result, the temperature rise of the resin 34 and 35 and the buffer material 41 and 42 is suppressed. Consequently, the deterioration of the constituent materials can be suppressed by lowering the temperature of the bottom of the cask body 12 and the lid 13.

[0049] The radioactive material storage container according to the second embodiment is the same as the radioactive material storage container according to the first embodiment, further comprising a resin (neutron shield) 34 placed at the bottom 29 of the cask body 12, and an insulating layer 51 placed inside the resin 34 at the bottom 29. As a result, although the cask body 12 will rise in temperature due to the transfer of heat from the radioactive waste, the insulating layer 51 will block the transfer of heat to the resin 34, thereby suppressing the deterioration of the resin 34 due to the temperature rise.

[0050] The third embodiment of the radioactive material storage container is a radioactive material storage container according to the first or second embodiment, further comprising a resin (neutron shield) 35 on the lid 13, and an insulating layer 71 positioned inside the resin 35 on the lid 13. As a result, although the lid 13 rises in temperature due to heat transfer from the radioactive waste, the insulating layer 71 blocks the transfer of heat to the resin 35, thereby suppressing deterioration of the resin 35 due to temperature rise.

[0051] The fourth embodiment of the radioactive material storage container is a radioactive material storage container according to the third embodiment, further comprising a lid 13 having a primary lid 31 that is detachably attached to the opening 22 and a secondary lid 32 that is detachably attached to the opening 22 and positioned outside the primary lid 31, with resin 35 positioned between the primary lid 31 and the secondary lid 32, and an insulating layer 71 positioned between the primary lid 31 and the resin 35. As a result, the primary lid 31 is heated by the transfer of heat from the radioactive waste, causing its temperature to rise, but the insulating layer 71 blocks the transfer of heat to the resin 35, thereby suppressing deterioration of the resin 35 due to the temperature rise.

[0052] The fifth embodiment of the radioactive material storage container is a radioactive material storage container according to any one of the first to fourth embodiments, and furthermore, the insulating layers 51,71 are hollow portions 52,72. This makes it possible to simplify the insulating layers 51,71.

[0053] The sixth embodiment of the radioactive material storage container is the fifth embodiment of the radioactive material storage container, wherein the hollow portions 52, 72 are further partitioned by metal members. This allows the heat insulating layers 51, 71 to be formed as suitable hollow portions 52, 72.

[0054] The seventh embodiment of the radioactive material storage container is a radioactive material storage container according to any one of the first to sixth embodiments, further comprising fins (heat dissipation parts) 61, 62 on the outer periphery of the cask body 12 outside the insulating layers 51, 71. As a result, the heat blocked by the insulating layers 51, 71 is transferred to the radially outward side of the cask body 12 and lid 13, and can be appropriately released to the outside by the fins 61, 62.

[0055] The eighth embodiment of the radioactive material storage container is a radioactive material storage container according to any one of the first to seventh embodiments, further comprising a metal gasket 81 positioned between the opening 22 of the cask body 12 and the lid 13, and a low thermal conductivity member 82 provided on the first stage portion (sheet surface) 22a of the metal gasket 81 in the cask body 12 or the lid 13. As a result, although the opening 22 of the cask body 12 rises in temperature due to the transfer of heat from the radioactive waste, the low thermal conductivity member 82 suppresses the transfer of heat to the metal gasket 81, thereby suppressing deterioration of the metal gasket 81 due to the temperature rise. [Explanation of Symbols]

[0056] 11. Cask (container for radioactive material) 12 Cask body 13 Lid 21 Main body 22 Opening 22a First stage (sheet surface) 23 Cavity 24 Basketball 25 cells 28, 34, 35 Resin 29 Bottom 31 Primary lid 32 Secondary lid 41,42 Buffer 43. Stand 44 Support part 51. Insulation layer 52 Hollow part 53 Metal plate 61, 62 fins (heat dissipation part) 71. Insulation layer 81 Metal gasket 82 Low thermal conductivity material

Claims

1. A cask body having a cavity inside and an opening on one side in the axial direction, The cask body has a lid that can be opened and closed, An insulating layer is provided on at least one of the bottom of the cask body and the lid, A radioactive material storage container equipped with [a specific feature].

2. A neutron shield is placed at the bottom of the cask body, and the heat insulating layer is placed inside the neutron shield at the bottom. A radioactive material storage container according to claim 1.

3. A neutron shield is placed in the lid portion, and the heat insulating layer is placed inside the neutron shield in the lid portion. A radioactive material storage container according to claim 1.

4. The lid portion comprises a primary lid that is detachably attached to the opening and a secondary lid that is detachably attached to the opening and positioned outside the primary lid, the neutron shield is positioned between the primary lid and the secondary lid, and the heat insulating layer is positioned between the primary lid and the neutron shield. A radioactive material storage container according to claim 3.

5. The aforementioned insulating layer is a hollow portion. A radioactive material storage container according to claim 1.

6. The aforementioned hollow portion is partitioned by a metal member. A radioactive material storage container according to claim 5.

7. The cask body is provided with a heat dissipation section on the outer periphery of the outer side of the heat insulating layer. A radioactive material storage container according to claim 1.

8. A gasket is placed between the opening of the cask body and the lid, and a low thermal conductivity member is provided on the sheet surface of the gasket in the cask body or the lid. A radioactive material storage container according to claim 1.

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