JP3814272B2 - Metal enclosure for radioactive material - Google Patents

Description

  The present invention relates to a metal hermetic container such as a so-called canister or metal cask that contains a radioactive substance that generates heat.

  High radioactive materials such as spent nuclear fuel are dismantled and reprocessed to recover useful materials such as plutonium. These spent fuels are stored in a sealed state until reprocessing. In this case, spent fuel is stored in a canister as a metal sealed container at a nuclear power plant, and this canister is stored in a transport cask and transported to an intermediate storage facility or reprocessing facility by a truck or the like. Stored. Or spent fuel is conveyed and stored in the state accommodated in the metal cask for transport storage.

  Usually, a canister has a cylindrical container body made of metal and a basket disposed in the container body, and a plurality of spent fuels are enclosed in the container body in a state supported by the basket. The The upper opening of the container body is closed by the welded primary lid and secondary lid. The metal cask is configured in substantially the same manner except that it is closed with a metal O-ring.

  In the canister and the metal cask configured as described above, there is a radial gap of about 5 to 10 mm between each fuel assembly and the basket, and there is a shaft between the fuel assembly and the lid. There is a gap of about 10-30 mm in the direction. Therefore, when an impact is received during an earthquake or the like, the fuel assembly and basket, or the fuel assembly and the lid collide, and a large impact load acts on the fuel assembly, resulting in damage to the fuel cladding tube, etc. May occur. In this case, radioactive material leaks from the spent fuel, and the soundness of the fuel assembly and the canister is impaired.

  The present invention has been made in view of the above points, and an object of the present invention is to provide a metal sealed container capable of preventing radiation leakage and ensuring soundness even when a large impact is applied.

In order to achieve the above object, the metal sealed container for radioactive materials according to the present invention proposes the following means (1) to (5).
(1) A substantially cylindrical container main body whose lower end is closed, and a basket which is disposed in the container main body and which has a plurality of elongated loading portions extending along the axial direction of the container main body. A radioactive substance aggregate loaded in the loading part and extending along the axial direction of the container body, and inserted in a radial gap between the radioactive substance aggregate and the basket in the loading part. Wedge-like first and second spacers arranged in a direction perpendicular to the axial direction of the basket and the upper end of the basket are fitted, and the first and second spacers are orthogonal to the axial direction of the loading part. And a pressing member that presses against the outer surface of the radioactive substance aggregate and the inner surface of the loading unit by pressing in a direction substantially parallel to the inner surface of the loading unit, and a lid that closes the upper end opening of the container body. It was It is characterized by a door.

(2) a substantially cylindrical container body with a closed lower end, a basket disposed in the container body, and formed with a plurality of elongated loading portions each extending along the axial direction of the container body; The radioactive substance aggregate loaded in the loading part and extending along the axial direction of the container body, and inserted in a radial gap between the radioactive substance aggregate and the basket in the loading part. Wedge-shaped first and first wedges which are arranged in a direction perpendicular to the axial direction and are pressed against the outer surface of the radioactive substance assembly and the inner surface of the loading unit by sliding with each other along the axial direction of the loading unit. 2 spacers and a lid that closes the upper end opening of the container body .

(3) a substantially cylindrical container body with a closed lower end, a basket disposed in the container body, and formed with a plurality of elongated loading portions each extending along the axial direction of the container body; A radioactive substance aggregate loaded in the loading section and extending along the axial direction of the container body; and inserted in a gap between the radioactive substance aggregate and the basket in the loading section; A wedge-shaped first and second spacer arranged in an orthogonal direction, and a lid that closes the upper end opening of the container body, the first spacer being located on the radioactive substance assembly side, The second spacer is located on the inner surface side of the loading portion, and one of the first and second spacers is between a pair of divided spacers separated in a direction parallel to the inner surface of the loading portion and the divided spacer. And a pressing member that moves the divided spacers according to a temperature change and presses the divided spacers against the other of the first and second spacers .

(4) In the metal sealed container for radioactive materials according to the means of (3), the pressing member is formed of bimetal.
(5) In the metal sealed container for radioactive substances according to the means (3), the pressing member is formed of a shape memory alloy .

  According to the metal sealed container configured as described above, by placing a buffer member or a spacer in the gap between the radioactive substance aggregate and the basket, the rattling of the radioactive substance aggregate with respect to the basket can be significantly reduced. Can do. Therefore, even when a large impact is applied to the metal hermetic container, the collision between the radioactive substance aggregate and the basket can be prevented, and the radioactive substance aggregate can be prevented from being damaged. As a result, it is possible to provide a metal sealed container that prevents leakage of radiation and can ensure soundness over a long period of time. The same applies to the spacer in the axial direction.

  According to the present invention, it is possible to provide a metal hermetic container for a radioactive substance that can prevent leakage of radiation and ensure soundness for a long period of time even when a large impact is applied.

Hereinafter, a concrete cask including a canister according to an embodiment of the present invention will be described in detail with reference to the drawings.
As shown in FIGS. 1 and 2, a concrete cask 10 as a concrete storage container includes a concrete container 12 that functions as a shielding structure, and a canister 14 is accommodated in the concrete container. As will be described later, the canister 14 is formed of a metal and is formed in a cylindrical shape closed at both ends, and a spent fuel assembly 42 is accommodated therein as a radioactive substance.

  The concrete container 12 of the concrete cask 10 has a closed cylindrical shape at the bottom, and is formed to have a height of about 6 m and a diameter of about 4 m, and the concrete wall thickness is about 0.9 m. Has been. The upper end opening of the concrete container 12 is closed by a concrete lid 20 whose outer surface is covered with a carbon steel plate. In the concrete wall of the concrete container 12, a bar arrangement (not shown) is provided.

  In the concrete container 12, a cylindrical storage portion 22 is defined by the inner peripheral surface of the concrete container and the lid 20. The canister 14 is stored in the storage unit 22. The canister 14 is placed on a plurality of ribs 31 formed on the bottom surface of the storage portion 22 and is arranged coaxially with the concrete container 12. The canister 14 is stored in the storage unit 22 with a predetermined gap, for example, a gap of about 10 cm, between the outer peripheral surface and the inner peripheral surface of the concrete container 12.

  A cooling air flow path 24 through which cooling air flows is formed by the gap between the outer peripheral surface of the canister 14 and the inner peripheral surface of the concrete container 12. The cooling air flow path 24 is formed over the entire outer peripheral surface of the canister 14 and over the entire axial length of the outer peripheral surface.

  A plurality of, for example, four intake ports 26 are formed at the bottom of the concrete container 12, and four exhaust ports 28 are formed at the upper end of the concrete container 12, and communicate with the cooling air flow path 24. . The four air inlets 26 are provided at equal intervals along the circumferential direction of the concrete container 12, and open to the bottom outer peripheral surface of the concrete container 12. Further, the exhaust ports 28 are provided at equal intervals along the circumferential direction of the concrete container 12, and open to the outer peripheral surface of the upper end portion of the concrete container 12.

  The intake port 26, the exhaust port 28, and the cooling air flow path 24 constitute a heat removal unit that removes heat from the concrete cask 10 by natural circulation cooling of air. That is, the outside air as the cooling air introduced into the concrete container 12 from the air inlet 26 flows around the canister 14 through the cooling air flow path 24, while removing the canister 14 and the concrete container 12 and cooling them. Then, the cooling air heated and heated by the heat from the canister 14 is discharged from the exhaust port 28 to the outside of the concrete container 12.

  On the other hand, a cylindrical liner 30 made of a metal such as carbon steel is provided on the inner peripheral surface of the concrete container 12. The liner 30 made of metal has higher heat transfer than that of concrete, and has a function of accelerating heat transfer of heat generated from the canister 14 and shielding radiation, mainly γ rays.

  Next, the configuration of the canister 14 will be described in detail. As shown in FIGS. 2 to 4, the canister 14 that functions as a metal hermetic container includes a cylindrical container body 15 whose lower end is closed, and a lid body to be described later which closes the upper end opening 11 of the container body. ing. A plurality of spent fuel assemblies 42 are enclosed in the container body 15 while being supported by the basket 40.

  The canister 14 has a welded and sealed structure so that the enclosed radioactive material does not leak to the outside. The container main body 15 is filled with an inert gas such as helium gas or a nitrogen gas in a negative pressure state or a positive pressure state.

  That is, a plurality of, for example, four support bases 35 are fixed to the inner peripheral surface of the upper end portion of the container body 15 and are provided at equal intervals along the circumferential direction. A disk-shaped shielding plate 38 is placed on the support base 35 via an annular support plate 36 or directly, and closes the upper end opening 11 of the container body 15.

  A disc-shaped primary lid 32 and secondary lid 34 are mounted in the upper end opening 11 of the container body 15 so as to overlap the shielding plate 38 and close the upper end opening 11 of the container body. Moreover, the upper end side part of the outer peripheral part of the primary cover 32 and the secondary cover 34 is welded to the internal peripheral surface of the container main body 15 over the perimeter.

  A plurality of axially symmetric recesses 39 are formed on the inner surface of the secondary lid 34. The inner surface of the secondary lid 34 is in close contact with the upper surface of the primary lid 32 except for these recesses 39. Due to the plurality of recesses 39, a sealed space functioning as a monitoring inspection space is formed between the primary lid 32 and the secondary lid 34, and the sealed space is maintained at a negative pressure or a positive pressure. . As a result, a pressure barrier is formed between the inside and outside of the canister 14, and monitoring is possible despite the close contact between the primary lid and the secondary lid.

  In this way, the upper end opening 11 of the container body 15 is airtightly closed by the shielding plate 38 as the lid, the primary lid 32, and the secondary lid 34. The container main body 15, the shielding plate 38, the primary lid 32, and the secondary lid 34 are made of, for example, a metal resistant to corrosion such as SUS329J4L, SUS329J3L, or SUS317 with Cr + 3Mo> 34%.

  On the other hand, as shown in FIGS. 2 to 5, the basket 40 disposed in the container main body 15 extends over almost the entire length of the container main body, and its cross section is formed in a lattice shape. Thereby, the basket 40 forms a plurality of loading portions 44 each having a rectangular cross section extending along the axial direction of the container body 15. The basket 40 is made of a composite material of boron (B) and aluminum or SUS.

  The spent fuel assembly 42 includes a radioactive substance that generates heat and radiation due to decay heat, such as spent fuel of a nuclear reactor. The spent fuel assembly 42 includes a plurality of elongated fuel rods 45 each of which contains spent fuel enclosed in a fuel cladding tube, an upper nozzle 46 that holds the upper end, middle portion, and lower end of these fuel rods, The nozzle 47 and the lower nozzle 48 are provided, and are formed in a substantially prismatic shape as a whole. Each spent fuel assembly 42 is held in a state of being inserted into the loading portion 44 of the basket 40 and extends over almost the entire length of the container body 15.

  Further, according to the present embodiment, each spent fuel assembly 42 is prevented from rattling in the loading portion 44 by the buffer member, and collision with the basket 40 is prevented. That is, as shown in FIG. 7, the buffer member 50 has a rectangular frame-shaped main body 51 and a plurality of engaging claws 52 extending from the main body, and is formed of aluminum or the like. Further, the main body 51 is formed with a plurality of through holes 53 extending along the axial direction, respectively, to allow the buffer member to be crushed when subjected to a large impact.

  The buffer member 50 is attached to the outer surface of the upper end portion of the spent fuel assembly from the upper end side of the basket 40 after inserting the spent fuel assembly 42 into the loading portion 44 of the basket 40. It arrange | positions in the clearance gap between an upper end part and a basket. In this case, the buffer member 50 is attached to the spent fuel assembly by engaging the engaging claw 52 with the lower edge of the upper nozzle 46 of the spent fuel assembly 42, and the main body 51 covers the outer peripheral surface of the upper nozzle 46. It is held in the state.

  According to the concrete cask canister 14 configured as described above, by placing the buffer member 50 in the gap between the spent fuel assembly 42 and the basket 40, the spent fuel assembly can be rattled against the basket. Can be greatly reduced. Therefore, even when a large impact is applied to the canister 14, the collision between the spent fuel assembly 42 and the basket 40 can be prevented, and the spent fuel assembly can be prevented from being damaged. Moreover, since the buffer member 50 has the some through-hole 53 and is a structure which is easy to be crushed, when a big impact effect | action acts, it can crushed and can absorb an impact. Therefore, it becomes possible to prevent the spent fuel assembly 42 from being damaged more reliably. From the above, it is possible to obtain a canister capable of preventing radiation leakage and ensuring soundness over a long period of time.

  Next, a canister according to another embodiment of the present invention will be described. In each embodiment described below, the same reference numerals are assigned to the same portions as those in the first embodiment described above, and the description thereof is omitted, and different portions will be described in detail.

  As shown in FIG. 8, according to the canister according to the second embodiment of the present invention, a plurality of, for example, eight buffer members 50 are provided for one spent fuel assembly 42. Each buffer member 50 is formed in a U-shaped cross section with aluminum, for example, and is fitted to the upper end portion of the basket 40 from above. In addition, a plurality of through holes 53 are formed in each buffer member 50 so as to be easily crushed when subjected to a large impact. The eight buffer members 50 are arranged so as to surround the outer surface of the upper nozzle 46 of the spent fuel assembly 42, and extend into the gap between the upper nozzle outer surface and the basket 40, respectively.

  When the spent fuel assembly 42 is stored in the canister 14, the buffer member 50 is attached to the basket 40 in advance, and the spent fuel assembly 42 is inserted into the basket loading portion 44 from above. Therefore, a guide surface 54 is formed at the upper end of each buffer member 50 so as to be inclined upward and outward so that the spent fuel assembly 42 can be smoothly stored.

  Also in the second embodiment configured as described above, by placing the buffer member 50 in the gap between the spent fuel assembly 42 and the basket 40, the spent fuel assembly is rattled against the basket. Even when a large impact is applied to the canister 14, the spent fuel assembly 42 can be prevented from being damaged. Moreover, since the buffer member 50 has the some through-hole 53 and is a structure which is easy to be crushed, when a big impact effect | action acts, it can crushed and can absorb an impact. Therefore, it becomes possible to prevent the spent fuel assembly 42 from being damaged more reliably. From the above, it is possible to obtain a canister capable of preventing radiation leakage and ensuring soundness over a long period of time.

  As shown in FIG. 9, according to the canister according to the third embodiment of the present invention, in each loading portion 44, the gap between the spent fuel assembly 42 and the basket 40 has a plurality of pipe-like shapes. The buffer member 50 is disposed and surrounds the spent fuel assembly. Each buffer member 50 is made of, for example, an aluminum hollow pipe. Each buffer member 50 extends substantially along the entire length of the loading portion 44 and along the axial direction of the loading portion. The basket 40 has a plurality of positioning grooves 56 formed on the inner surface of the loading portion 44, and each positioning groove extends over the entire length of the loading portion 44 and along the axial direction of the loading portion. It extends. Each buffer member 50 is disposed in the positioning groove 56 and is held at a desired position.

  As shown in FIG. 10, according to the canister according to the fourth embodiment of the present invention, in each loading portion 44, a particulate buffer is provided in the gap between the spent fuel assembly 42 and the basket 40. The material 60 is filled. As the buffer material 60, for example, aluminum particles or hollow spheres having a diameter of 2 to 3 mm are used.

  Also in the third and fourth embodiments configured as described above, a pipe-shaped cushioning member 50 is arranged in the gap between the spent fuel assembly 42 and the basket 40 or a granular cushioning material 60 is filled. By doing so, rattling of the spent fuel assembly with respect to the basket can be greatly reduced, and damage to the spent fuel assembly 42 can be prevented even when a large impact is applied to the canister 14. In addition, the shock absorbing member 50 and the shock absorbing material 60 can be crushed and absorb the shock when a large shock acts. Therefore, it becomes possible to prevent the spent fuel assembly 42 from being damaged more reliably. From the above, it is possible to obtain a canister capable of preventing radiation leakage and ensuring soundness over a long period of time.

As shown in FIGS. 11 and 12, according to the canister according to the fifth embodiment of the present invention, in each loading portion 44, the gap between each side surface of the spent fuel assembly 42 and the basket 40 is provided. Are inserted with wedge-shaped first and second spacers 62 and 64 made of aluminum, respectively. The first and second spacers 62 and 64 extend over substantially the entire length of the loading portion 44 in the axial direction. The first spacer 62 is provided in contact with the side surface of the spent fuel assembly 42, and the second spacer 64 is provided in contact with the inner surface of the loading portion 44 , that is, the basket 40. The first and second spacers 62 and 64 are positioned so as to overlap each other in a direction perpendicular to the axial direction of the loading portion 44 with their inclined surfaces in contact with each other. The first and second spacers 62 and 64, the inner surface parallel to the direction of instrumentation Hama portion 44, and is provided slidably along a direction perpendicular to the axial direction of the instrumentation Hama portion 44.

  In addition, four pressing members 66 are fitted to the upper end portion of the basket 4, and are respectively located at positions corresponding to the four corner portions of the loading portion 44. Each pressing member 66 has a cross section formed in a substantially cross shape, and has four pressing portions 67 inserted into a gap between the spent fuel assembly 42 and the basket 40. Each pressing portion 67 has a pressing surface 68 that is inclined so as to be tapered.

  In the loading process, after the spent fuel assembly 42 and the four sets of first and second spacers 62 and 64 are loaded into the loading portion 44 of the basket 40, the four pressing members 66 are placed on the upper end of the basket 40 from above. Mating. Then, as shown in FIG. 12, the first and second spacers 62 and 64 of each set are pressed in directions opposite to each other by the pressing surfaces 68 of the pressing members 66 located on both sides thereof. Therefore, the first and second spacers 62 and 64 are pressed against the side surface of the spent fuel assembly 42 and the inner surface of the loading portion 44 by the interaction due to the wedge shape.

  Therefore, according to the fifth embodiment configured as described above, rattling of the spent fuel assembly 42 is suppressed by the first and second spacers 62 and 64, and a large impact acts on the canister 14. Even in this case, damage to the spent fuel assembly 42 can be prevented. As a result, it is possible to obtain a canister that prevents leakage of radiation and can ensure soundness over a long period of time.

As shown in FIGS. 13 and 14, according to the canister according to the sixth embodiment of the present invention, in each loading portion 44, the gap between each side surface of the spent fuel assembly 42 and the basket 40 is provided. Are inserted with wedge-shaped first and second spacers 62 and 64 made of aluminum, respectively. The first and second spacers 62 and 64 extend over substantially the entire length of the loading portion 44 in the axial direction. The first spacer 62 is provided in contact with the side surface of the spent fuel assembly 42, and the second spacer 64 is provided in contact with the inner surface of the loading portion 44, that is, the basket 40. The first and second spacers 62 and 64 are positioned so as to overlap each other in a direction perpendicular to the axial direction of the loading portion 44 with their inclined surfaces in contact with each other. The first and second spacers 62, 64 are slidable along the axial direction of the instrumentation Hama portion 44.

  In the loading process, after the spent fuel assembly 42 is loaded into the loading portion 44 of the basket 40, each of the second spacers 64 among the four sets of the first and second spacers 62 and 64 is used as the spent fuel assembly. Insert between baskets. Next, each second spacer 64 is inserted between the spent fuel assembly 42 and the second spacer 64 from above, and is slid on the second spacer 64 along the axial direction of the loading portion 44 in the vicinity of the lower end portion. Push in. Thereby, the first and second spacers 62 and 64 are pressed against the side surface of the spent fuel assembly 42 and the inner surface of the loading portion 44 by the interaction due to the wedge shape.

  Therefore, according to the sixth embodiment configured as described above, the spent fuel assembly 42 is restrained from rattling by the first and second spacers 62 and 64, and a large impact acts on the canister 14. Even in this case, damage to the spent fuel assembly 42 can be prevented. As a result, it is possible to obtain a canister that prevents leakage of radiation and can ensure soundness over a long period of time.

  As shown in FIG. 15, according to the canister according to the seventh embodiment of the present invention, each loading portion 44 has a gap between each side surface of the spent fuel assembly 42 and the basket 40. Wedge-shaped first and second spacers 62 and 64 made of aluminum are inserted. The first and second spacers 62 and 64 extend only over the upper end portion of the loading portion 44 or over almost the entire length in the axial direction. Further, the first spacer 62 is disassembled into two parts and is provided in contact with the side surface of the spent fuel assembly 42. The second spacer 64 is divided into a pair of divided spacers 64 a and is provided in contact with the inner surface of the loading portion 44, that is, the basket 40. Further, the pair of divided spacers 64a are connected to each other via a bimetal 64b as a pressing member. Note that a shape memory alloy may be used as the pressing member.

The first and second spacers 62 and 64 are positioned so as to overlap each other in a direction perpendicular to the axial direction of the loading portion 44 with their inclined surfaces in contact with each other. Also, split spacer 64a is provided slidably along a direction perpendicular to the inner surface direction parallel to the instrumentation Hama portion 44, and the axial direction of the instrumentation Hama portion 44.

  According to the seventh embodiment configured as described above, when the inside of the canister reaches a high temperature of about 200 ° C., each pair of bimetals 64 expands and expands the pair of divided spacers 64a, and the pair of first spacers Press to 62. Therefore, the first and second spacers 62 and 64 of each set are pressed against the side surface of the spent fuel assembly 42 and the inner surface of the loading portion 44 by the interaction due to the wedge shape.

  Therefore, according to the seventh embodiment configured as described above, the spent fuel assembly 42 is restrained from rattling by the first and second spacers 62 and 64, and a large impact acts on the canister 14. Even in this case, damage to the spent fuel assembly 42 can be prevented. As a result, it is possible to obtain a canister that prevents leakage of radiation and can ensure soundness over a long period of time.

  As shown in FIG. 16, according to the canister according to the eighth embodiment of the present invention, each loading portion 44 has a gap between each side surface of the spent fuel assembly 42 and the basket 40. Wedge-shaped first and second spacers 62 and 64 made of aluminum are inserted. The first and second spacers 62 and 64 extend only over the upper end portion of the loading portion 44 or over almost the entire length in the axial direction. Further, the first spacer 62 is disassembled into a pair of divided spacers 62 a and is provided in contact with the side surface of the spent fuel assembly 42. The pair of split spacers 62a are connected to each other via a spring-shaped shape memory alloy 62b as a pressing member. Further, the second spacer 64 is provided in contact with the inner surface of the loading portion 44, that is, the basket 40.

The pair of divided spacers 62 a and the second spacer 64 are positioned so as to overlap in a direction orthogonal to the axial direction of the loading portion 44 with the inclined surfaces in contact with each other. Also, split spacer 62a is provided slidably along a direction perpendicular to the inner surface direction parallel to the instrumentation Hama portion 44, and the axial direction of the instrumentation Hama portion 44.

  According to the eighth embodiment configured as described above, when the inside of the canister reaches a high temperature of about 200 ° C., the shape memory alloy of each spacer set contracts and pulls the pair of divided spacers 62a toward each other. And press against the second spacer 64. Therefore, the divided spacer 62 and the second spacer 64 constituting the first spacer of each set are pressed against the side surface of the spent fuel assembly 42 and the inner surface of the loading portion 44 by the interaction due to the wedge shape, respectively.

  Therefore, according to the eighth embodiment configured as described above, the spent fuel assembly 42 is restrained from rattling by the first and second spacers 62 and 64, and a large impact acts on the canister 14. Even in this case, damage to the spent fuel assembly 42 can be prevented. As a result, it is possible to obtain a canister that prevents leakage of radiation and can ensure soundness over a long period of time.

In each of the first to eighth embodiments described above, a third spacer that prevents rattling of the spent fuel assembly 42 in the axial direction may be used in combination.
For example, as shown in FIG. 17, a plurality of third spacers 80 are fixed to the inner surface of the shielding plate 38 in the canister. The third spacer 80 functions as a spacer in the present invention, is formed in a cylindrical shape, a rectangular tube shape, a columnar shape, a rectangular column shape, or the like, and is welded or bolted to the shielding plate 38. Each third spacer 80 extends from the shielding plate 38 into the loading portion 44 of the basket 40 along the axial direction of the canister, and faces the upper end of the spent fuel assembly with a predetermined gap. The gap between the third spacer 80 and the spent fuel assembly 42 is appropriately set in consideration of irradiation growth of the spent fuel.

  As described above, by providing the third spacer 80 in the axial gap between each spent fuel assembly 42 and the shielding plate 38, it is possible to prevent the spent fuel assembly 42 from rattling in the axial direction. Can do. Therefore, even when a large impact in the axial direction acts on the canister 14, the collision between the spent fuel assembly 42 and the shielding plate 38 can be prevented, and the spent fuel assembly can be prevented from being damaged. Further, by making the third spacer 80 to be easily crushed, it can be crushed and absorb the impact when a large impact is applied. Therefore, it becomes possible to prevent the spent fuel assembly 42 from being damaged more reliably. From the above, it is possible to obtain a canister capable of preventing radiation leakage and ensuring soundness over a long period of time.

  Further, the third spacer 80 is not limited to being fixed to the shielding plate 38, and as shown in FIG. 18, a plurality of third spacers are fixed to the holding plate 82 and the holding plate is placed on the basket 40. It is good.

In this case, each third spacer 80 is formed in a cylindrical shape, a rectangular tube shape, a columnar shape, a prismatic shape, or the like, and is welded to the holding plate 82. Each third spacer 80 extends vertically from the holding plate 82 along the axial direction of the canister. The lower part of each third spacer 80 extends into the loading portion 44 of the basket 40 and faces the upper end of the spent fuel assembly with a predetermined gap. Further, the upper part of each third spacer 80 faces the shielding plate 38 with a predetermined gap.
Even in such a configuration, the third spacer 80 can prevent the spent fuel assembly 42 from rattling in the axial direction, and the same effect as described above can be obtained.

  In addition, the present invention is not limited to the above-described embodiment, and various modifications can be made within the scope of the present invention. For example, the material constituting each member such as the buffer member and the spacer is not limited to the above-described embodiment, and can be selected as necessary. Moreover, although the shape of the spent fuel assembly and the loading portion of the basket is a prismatic shape, the shape is not limited to this, and other shapes may be adopted as necessary.

  Furthermore, this invention is applicable not only to the above-mentioned canister but also to other metal sealed containers such as a metal cask. Further, the basket is not limited to the one having the integral structure described above, and may be formed by combining a plurality of cylindrical members defining the loading portion.

Sectional drawing of the concrete cask provided with the canister which concerns on embodiment of this invention. FIG. 2 is a cross-sectional view taken along line AA in FIG. 1. The perspective view which fractures | ruptures and shows a part of said canister. Sectional drawing of the said canister. The perspective view which shows the basket in the said canister. The perspective view which shows the spent fuel assembly accommodated in the said canister. The top view and sectional drawing which show the said basket and spent fuel assembly, and the perspective view which shows a buffer member. The top view and sectional drawing which show the basket of the canister which concerns on 2nd Embodiment of this invention, a spent fuel assembly, and a buffer member. The top view which shows the basket of the canister which concerns on 3rd Embodiment of this invention, a spent fuel assembly, and a buffer member. The top view which shows the basket of the canister which concerns on 4th Embodiment of this invention, the used fuel assembly | assembly, and a shock absorbing material. The top view which shows the basket of the canister which concerns on 5th Embodiment of this invention, a spent fuel assembly, a spacer, and a press member. The figure which shows schematically the pressing operation of the spacer in the canister which concerns on the said 5th Embodiment. The top view which shows the basket of the canister which concerns on 6th Embodiment of this invention, the spent fuel assembly | assembly, and a spacer. Sectional drawing which shows the basket of the canister concerning the said 6th Embodiment, a spent fuel assembly, and a spacer. The top view which shows the basket of the canister concerning the 7th Embodiment of this invention, the spent fuel assembly | assembly, and a spacer. The top view which shows the basket of the canister which concerns on 8th Embodiment of this invention, the spent fuel assembly | assembly, and a spacer. Sectional drawing which shows schematically the canister which concerns on other embodiment of this invention provided with the 3rd spacer. Sectional drawing which shows roughly the canister which concerns on other embodiment of this invention provided with the 3rd spacer.

Explanation of symbols

10 ... Concrete cask, 14 ... Canister, 15 ... Container body,
32 ... Primary lid, 34 ... Secondary lid, 40 ... Basket, 42 ... Spent fuel assembly,
44 ... loading section, 45 ... fuel rod, 46 ... upper nozzle, 50 ... cushioning member,
51 ... Main body, 52 ... Engaging claw, 53 ... Through hole, 60 ... Buffer material
62 ... 1st spacer, 64 ... 2nd spacer, 66 ... Pressing member,
68 ... Pressing surface, 62a, 64a ... Division spacer, 64b ... Bimetal,
62b ... shape memory alloy, 80 ... third spacer.

Claims (5)

A substantially cylindrical container body closed at the lower end; a basket disposed in the container body; and a plurality of elongated loading parts each extending along the axial direction of the container body; And the radioactive substance aggregate that is loaded along the axial direction of the container body, and is inserted into a radial gap between the radioactive substance aggregate and the basket in the loading portion, and the axial direction of the loading portion. Wedge-like first and second spacers arranged in an orthogonal direction and fitted to the upper end of the basket, the first and second spacers being orthogonal to the axial direction of the loading unit and the loading unit the inner surface and the pressing member is pressed in a direction generally parallel pressed against the outer surface and inner surface of the loading portion of the radioactive material aggregates, a lid which closes the top opening of the container body, further comprising a Metal sealed container for radioactive material and symptoms. A substantially cylindrical container body closed at the lower end; a basket disposed in the container body; and a plurality of elongated loading parts each extending along the axial direction of the container body; A radioactive substance aggregate that is loaded on the container body and extends along the axial direction of the container body, and is inserted into a radial gap between the radioactive substance aggregate and the basket in the loading section. Wedge-like first and second spacers arranged in an orthogonal direction and pressed against the outer surface of the radioactive substance aggregate and the inner surface of the loading unit by sliding with each other along the axial direction of the loading unit metal sealed container for radioactive material, characterized in that it and a lid closing the top opening of the container body.   A substantially cylindrical container body closed at the lower end; a basket disposed in the container body; and a plurality of elongated loading parts each extending along the axial direction of the container body; A radioactive substance aggregate loaded in the container body and extending along the axial direction of the container body, and a direction perpendicular to the axial direction of the loading part inserted in the gap between the radioactive substance aggregate and the basket in the loading section A wedge-shaped first and second spacers disposed on top of each other, and a lid that closes an upper end opening of the container body, wherein the first spacer is located on the radioactive substance assembly side, and the second spacer Is located on the inner surface side of the loading portion, and one of the first and second spacers is disposed between a pair of divided spacers separated in a direction parallel to the inner surface of the loading portion and the divided spacers. Metal sealed container for radioactive material, characterized in that it comprises a pressing member for pressing by moving the split spacer in accordance with temperature change at the other of said first and second spacers, the. 4. The metal sealed container for radioactive materials according to claim 3 , wherein the pressing member is formed of bimetal. 4. The metal sealed container for radioactive substances according to claim 3 , wherein the pressing member is made of a shape memory alloy .

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