JP2002341085A - Metal closed vessel for radioactive material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a metal closed vessel capable of preventing leakage of radiation even when a large impact is acted thereon, and guaranteeing soundness over a long period. SOLUTION: A basket 40 is arranged in the vessel body of a canister, and the basket forms plural long and narrow loading parts 44 extending respectively along the axial direction of the vessel body. A radioactive material aggregate 42 is loaded in the loading parts and extended along the axial direction of the vessel body. A buffer member 50 is mounted on the outside face of the upper end part of the radioactive material aggregate and positioned in a gap between the upper end part of the radioactive material aggregate and the basket, to thereby suppress looseness of the radioactive material aggregate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal sealed container such as a so-called canister, metal cask, or the like, for storing radioactive substances that generate heat.

[0002]

2. Description of the Related Art Highly radioactive materials typified by spent fuel of nuclear reactors are dismantled and reprocessed to recover reusable useful materials such as plutonium.
These spent fuels are stored in a sealed state until reprocessing. In this case, the spent fuel is stored in a canister as a metal sealed container at the nuclear power plant, and the canister is transported to an intermediate storage facility or a reprocessing facility by a truck or the like while being stored in a transport cask. Is stored. Alternatively, the spent fuel is transported and stored in a state of being stored in a transport and storage metal cask.

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 stored in the container body while being supported by the basket. The body is enclosed. The upper opening of the container body is closed by the welded primary lid and secondary lid. The metal cask has substantially the same configuration except that it is closed by a metal O-ring.

[0004]

In the canister and metal cask constructed as described above, there is a radial gap of about 5 to 10 mm between each fuel assembly and the basket. There is a gap of about 10 to 30 mm in the axial direction between the cover and the lid. Therefore, if an impact occurs during an earthquake or the like, the fuel assembly and the basket, or the fuel assembly and the lid collide, causing a large impact load to act on the fuel assembly, resulting in damage to the fuel cladding tube, etc. May occur. In this case, radioactive materials leak from the spent fuel, and the integrity of the fuel assembly and the canister is impaired.

[0005] 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 that can prevent radiation from leaking even when a large impact acts and can maintain soundness.

[0006]

In order to achieve the above object, a metal hermetic container according to the present invention is provided with a substantially cylindrical container body having a closed lower end, and disposed inside the container body. A basket formed with a plurality of elongated loading portions extending along the axial direction of the container body, a radioactive substance aggregate loaded in the loading portion and extending along the axial direction of the container body, and an upper end of the container body A lid having an opening closed, a buffer member attached to the radioactive substance aggregate, and positioned in a radial gap between the radioactive substance aggregate and the basket, and a cover member between the radioactive substance aggregate and the lid. And a spacer located in the axial gap.

Further, according to another metal closed container according to the present invention, the buffer member is fitted to the basket and extends into the radial gap between the radioactive substance aggregate and the basket. . Further, a spacer is provided in an axial gap between the fuel assembly and the lid.

According to still another metal closed container according to the present invention, a plurality of pipe-shaped buffer members are inserted into a gap between the radioactive substance aggregate and the basket in the loading portion, or a granular buffer member is inserted. Buffer material is filled.

Further, another metal sealed container according to the present invention is inserted in a gap between the radioactive substance aggregate and the basket in the loading section and is arranged so as to overlap in a direction orthogonal to the axial direction of the loading section. The wedge-shaped first and second spacers are fitted to the upper end of the basket, and the first and second spacers are oriented in a direction perpendicular to the axial direction of the loading portion and substantially parallel to the inner surface of the loading portion. And a pressing member that presses against the outer surface of the radioactive substance aggregate and the inner surface of the loading section.

According to still another metal closed container according to the present invention, the first and second wedge-shaped first and second wedges are formed in the gap between the radioactive substance aggregate and the basket in the loading section.
Spacers are inserted, and these spacers are arranged so as to overlap in a direction orthogonal to the axial direction of the loading section, and slide along each other along the axial direction of the loading section to form the outer surface of the radioactive substance aggregate and the outer surface. It is pressed against the inner surface of the loading section.

Further, according to another metal sealed container according to the present invention, a spacer unit is disposed in a gap between the radioactive substance aggregate and the basket in the loading section, and the spacer unit is provided with the radioactive substance. A first spacer positioned on the assembly side and a second spacer positioned on the inner surface side of the loading portion, wherein one of the first and second spacers is separated in a direction parallel to the inner surface of the loading portion. A pair of split spacers and a pressing member that is arranged between the split spacers and moves the split spacer in response to a change in temperature and presses the split spacer against the other of the first and second spacers.

According to the metal hermetic container configured as described above, the cushioning member or the spacer is arranged in the gap between the radioactive substance aggregate and the basket, so that the play of the radioactive substance aggregate with respect to the basket is greatly reduced. Can be reduced. Therefore, even when a large impact acts on the metal sealed container, collision between the radioactive substance aggregate and the basket can be prevented, and damage to the radioactive substance aggregate can be prevented. As a result, it is possible to provide a metal sealed container that can prevent radiation from leaking and can ensure soundness over a long period of time. This is the same for the axial spacer.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A concrete cask provided with a canister according to an embodiment of the present invention will be described below 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 functioning as a shielding structure, and a canister 14 is housed in the concrete container. As will be described later, the canister 14 is formed of a metal and formed in a cylindrical shape with both ends closed, and contains a spent fuel assembly 42 as a radioactive substance.

The concrete container 12 of the concrete cask 10 has a cylindrical shape with a closed bottom and is formed, for example, to a height of about 6 m and a diameter of about 4 m, and a concrete wall thickness of about 0.9 m. It is formed to the extent. 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 addition, the inside of the concrete wall of the concrete container 12 is provided with reinforcing bars (not shown).

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 housed in the housing 22. The canister 14 is placed on a plurality of ribs 31 formed on the bottom surface of the storage section 22 and is arranged coaxially with the concrete container 12. Further, the canister 14 is provided 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, and the canister 14 is placed in the storage section 22.
Is housed inside.

The gap between the outer peripheral surface of the canister 14 and the inner peripheral surface of the concrete container 12 forms a cooling air passage 24 through which cooling air flows. The cooling air passage 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.
Each is communicated with the cooling air passage 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 section for removing 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 intake port 26 flows around the canister 14 through the cooling air flow path 24, and during that time, removes heat and cools the canister 14 and the concrete container 12.
Then, the cooling air heated and heated by the heat from the canister 14 is supplied from the exhaust port 28 to the concrete container 12.
Is discharged to the outside.

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

Next, the configuration of the canister 14 will be described in detail. As shown in FIGS. 2 to 4, the canister 14 functioning as a metal hermetic container includes a cylindrical container main body 15 having a closed lower end, and a lid described later closing an upper end opening 11 of the container main body. ing. And the container body 1
A plurality of spent fuel assemblies 42 are sealed in 5 while being supported by a basket 40.

The canister 14 has a hermetically sealed structure so that the enclosed radioactive substance does not leak outside. The container 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 shield 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 a secondary lid 34 are mounted in the upper end opening 11 of the container main body 15 so as to overlap with the shielding plate 38 to close the upper end opening 11 of the container main body. Further, the upper end side portions of the outer peripheral portions of the primary lid 32 and the secondary lid 34 are welded to the inner peripheral surface of the container body 15 over the entire periphery.

On the inner surface of the secondary lid 34, a plurality of axially symmetric recesses 39 are formed. 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. By the plurality of recesses 39, a closed space functioning as a monitoring inspection space is formed between the primary lid 32 and the secondary lid 34, and the inside of the closed space is maintained at a negative pressure or a positive pressure. . As a result, a pressure barrier is formed between the inside and the outside of the canister 14, and monitoring is possible despite the close contact between the primary lid and the secondary lid.

As described above, the upper end opening 11 of the container body 15 is airtightly closed by the shielding plate 38, the primary lid 32, and the secondary lid 34 as lids. The container body 15, the shielding plate 38, the primary lid 32, and the secondary lid 34
Is, for example, SUS329J4 with Cr + 3Mo> 34%
L, SUS329J3L, SUS317 or the like, and is formed of a metal having high corrosion resistance.

On the other hand, as shown in FIGS. 2 to 5, the basket 40 arranged in the container main body 15 extends over substantially 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 sections 44 each having a rectangular cross section and 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 due to decay heat and generates radiation, such as spent fuel of a nuclear reactor. Spent fuel assembly 4
Reference numeral 2 denotes a plurality of elongated fuel rods 45 each having spent fuel sealed in a fuel cladding tube, and an upper nozzle 46, an intermediate nozzle 47, and a lower part holding upper, middle and lower ends of these fuel rods. And a nozzle 48, and is 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 substantially the entire length in the container body 15.

Further, according to the present embodiment, rattling of each spent fuel assembly 42 in the loading section 44 is suppressed by the buffer member, and collision with the basket 40 is prevented. That is, as shown in FIG.
A rectangular frame-shaped main body 51 and a plurality of engaging claws 5 extending from the main body
And made of aluminum or the like.
In addition, a plurality of through holes 53 extending in the axial direction are formed in the main body 51 to allow the cushioning member to be crushed when a large impact is received.

After the spent fuel assembly 42 is inserted into the loading portion 44 of the basket 40, the buffer member 50 is mounted on the outer surface of the upper end of the spent fuel assembly from the upper end of the basket 40, and It is located in the gap between the upper end of the assembly and the basket. In this case, the cushioning member 50
The upper claw 52 of the spent fuel assembly 42 is
6 is attached to the spent fuel assembly by engaging with the lower edge, and the main body 51 is held so as to cover the outer peripheral surface of the upper nozzle 46.

According to the concrete cask canister 14 configured as described above, the spent fuel assembly 42
By arranging the cushioning member 50 in the gap between the basket and the basket 40, rattling of the spent fuel assembly with respect to the basket can be significantly reduced. Therefore, even when a large impact acts on the canister 14, the collision between the spent fuel assembly 42 and the basket 40 can be prevented, and damage to the spent fuel assembly can be prevented. Further, since the buffer member 50 has a plurality of through holes 53 and is easily collapsed, it can be crushed and absorb a shock when a large impact is applied. Therefore, it is possible to more reliably prevent the spent fuel assembly 42 from being damaged. From the above, it is possible to obtain a canister that can prevent leakage of radiation and can maintain soundness over a long period of time.

Next, a canister according to another embodiment of the present invention will be described. In each of the embodiments described below, the same parts as those in the above-described first embodiment are denoted by the same reference numerals, and description thereof will be omitted. Different parts 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. I have. Each cushioning member 50 is formed of, for example, aluminum and has a U-shaped cross section, and is fitted to the upper end of the basket 40 from above. Further, a plurality of through-holes 53 are formed in each buffer member 50 so as to be easily crushed when receiving a large impact. Then, the eight cushioning members 50
Are arranged so as to surround the outer surface of the upper nozzle 46 of the spent fuel assembly 42, and each extend into the gap between the outer surface of the upper nozzle 46 and the basket 40.

When storing the spent fuel assembly 42 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 loading portion 44 of the basket from above. Therefore, a guide surface 54 is formed at the upper end of each cushioning member 50 so as to extend upward and incline outward so that the spent fuel assembly 42 can be stored smoothly.

In the second embodiment configured as described above, the buffer member 50 is disposed in the gap between the spent fuel assembly 42 and the basket 40, so that the spent fuel The rattling is greatly reduced, and even when a large impact acts on the canister 14,
Damage to the spent fuel assembly 42 can be prevented.
Further, since the buffer member 50 has a plurality of through holes 53 and is easily collapsed, it can be crushed and absorb a shock when a large impact is applied. Therefore, it is possible to more reliably prevent the spent fuel assembly 42 from being damaged.
From the above, it is possible to obtain a canister that can prevent leakage of radiation and can maintain 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, the gap between the spent fuel assembly 42 and the basket 40 is Is disposed, and surrounds the spent fuel assembly. Each buffer member 50 is formed of, for example, a hollow aluminum pipe. Each buffer member 50 extends over substantially the entire length of the loading section 44 and along the axial direction of the loading section. In addition,
The basket 40 has a plurality of positioning grooves 56 formed on the inner surface of the loading section 44, respectively, and each positioning groove extends over substantially the entire length of the loading section 44 and along the axial direction of the loading section. I have. Each buffer member 50 is arranged 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 of the loading sections 44, the gap between the spent fuel assembly 42 and the basket 40 has a particle size. Buffer material 60 is filled. As the cushioning 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, the pipe-shaped buffer member 50 is disposed in the gap between the spent fuel assembly 42 and the basket 40.
Alternatively, by filling the granular cushioning material 60, rattling of the spent fuel assembly with respect to the basket is significantly reduced, and even if a large impact acts on the canister 14, damage to the spent fuel assembly 42 is prevented. can do. Further, when a large shock acts, the buffer member 50 and the buffer material 60 are crushed and can absorb the shock. Therefore, it is possible to more reliably prevent the spent fuel assembly 42 from being damaged. From the above, it is possible to obtain a canister that can prevent leakage of radiation and can maintain 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 space between each side surface of the spent fuel assembly 42 and the basket 40 is provided. In the gaps, wedge-shaped first and second spacers 62 and 64 each made of aluminum are provided.
Is inserted. First and second spacers 62, 64
Extends 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 section 44, that is, the basket 40. Then, the first and second spacers 62 and 64 are positioned so as to overlap in a direction orthogonal to the axial direction of the loading portion 44 in a state where their inclined surfaces are in contact with each other. The first and second spacers 62 and 64 are slidably provided in a direction parallel to the inner surface of the mounting portion 44 and in a direction orthogonal to the axial direction of the mounting portion.

Four pushing members 66 are fitted to the upper end of the basket 4 and are located at positions corresponding to the four corners of the loading section 44, respectively. Each pressing member 66
The four pressing portions 67 each having a substantially cross-shaped cross section and inserted into the gap between the spent fuel assembly 42 and the basket 40
have. Each pressing portion 67 has a pressing surface 68 which is inclined so as to be tapered.

In the loading step, the loading section 4 of the basket 40
After the spent fuel assembly 42 and the four sets of the first and second spacers 62 and 64 are loaded into the four pressing members 6
6 is fitted to the upper end of the basket 40 from above. Then, as shown in FIG. 12, the first and second spacers 62 and 64 of each pair 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 respectively connected to the spent fuel assembly 4 by a wedge-shaped interaction.
2 and the inner surface of the loading section 44.

Therefore, according to the fifth embodiment configured as described above, the rattle of the spent fuel assembly 42 is suppressed by the first and second spacers 62 and 64,
Even when a large impact acts on the canister 14, the spent fuel assembly 42 can be prevented from being damaged. As a result, it is possible to obtain a canister that can prevent radiation from leaking 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 space between each side surface of the spent fuel assembly 42 and the basket 40 is provided. In the gaps, wedge-shaped first and second spacers 62 and 64 each made of aluminum are provided.
Is inserted. First and second spacers 62, 64
Extends 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 section 44, that is, the basket 40. Then, the first and second spacers 62 and 64 are positioned so as to overlap in a direction orthogonal to the axial direction of the loading portion 44 in a state where their inclined surfaces are in contact with each other. The first and second spacers 62 and 64 are provided slidably along the axial direction of the mounting section 44.

In the loading step, the loading section 4 of the basket 40
After the spent fuel assemblies 42 are loaded into the four
And each of the second spacers 6 among the second spacers 62 and 64
4 is inserted between the spent fuel assembly and the basket.
Next, each of the second spacers 64 is inserted between the spent fuel assembly 42 and the second spacer 64 from above, and slides on the second spacer 64 along the axial direction of the loading portion 44 to move the vicinity of the lower end. Press it in until As a result, 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, respectively, by the interaction in a wedge shape.

Therefore, according to the sixth embodiment configured as described above, the rattle of the spent fuel assembly 42 is suppressed by the first and second spacers 62, 64,
Even when a large impact acts on the canister 14, the spent fuel assembly 42 can be prevented from being damaged. As a result, it is possible to obtain a canister that can prevent radiation from leaking 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 side of the spent fuel assembly 42 and the basket 40
Wedge-shaped first and second spacers 62 and 64 made of aluminum are inserted into gaps between the first and second spacers. The first and second spacers 62 and 64 are provided in the loading section 4.
4 extends over only the upper end portion or substantially the entire length in the axial direction. Further, the first spacer 62 is disassembled into two parts, each of which is provided in contact with the side surface of the spent fuel assembly 42. The second spacer 64 is a pair of divided spacers 64a.
And is provided in contact with the inner surface of the loading section 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, 6
Reference numeral 4 denotes a state in which the inclined surfaces are in contact with each other, and overlaps in a direction orthogonal to the axial direction of the loading section 44. The split spacer 64a is slidably provided in a direction parallel to the inner surface of the mounting portion 44 and in a direction orthogonal to the axial direction of the mounting portion.

According to the seventh embodiment configured as described above, when the inside of the canister is heated to a high temperature of about 200 ° C., each pair of bimetals 64 expands to push out a pair of divided spacers 64a, and a pair of divided spacers 64a are expanded. Press against the first spacer 62. Therefore, each set of the first and second spacers 62, 6
4 are pressed against the side surface of the spent fuel assembly 42 and the inner surface of the loading portion 44, respectively, by interaction in a wedge shape.

Therefore, according to the seventh embodiment configured as described above, the rattle of the spent fuel assembly 42 is suppressed by the first and second spacers 62, 64,
Even when a large impact acts on the canister 14, the spent fuel assembly 42 can be prevented from being damaged. As a result, it is possible to obtain a canister that can prevent radiation from leaking 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 side of the spent fuel assembly 42 and the basket 40
Wedge-shaped first and second spacers 62 and 64 made of aluminum are inserted into gaps between the first and second spacers. The first and second spacers 62 and 64 are provided in the loading section 4.
4 extends over only the upper end portion or substantially the entire length in the axial direction. Further, the first spacer 62 is disassembled into a pair of divided spacers 62a, and is provided in contact with the side surface of the spent fuel assembly 42, respectively. The pair of divided spacers 62a are connected to each other via a spring-shaped shape memory alloy 62b as a pressing member. Furthermore, the second
The spacer 64 is provided in contact with the inner surface of the loading section 44, that is, the basket 40.

Then, the pair of divided spacers 62a and the second
The spacer 64 and the inclined surfaces thereof are in contact with each other, and overlap with each other in a direction orthogonal to the axial direction of the loading portion 44. The split spacer 62a is slidably provided in a direction parallel to the inner surface of the mounting portion 44 and in a direction orthogonal to the axial direction of the mounting portion.

According to the eighth embodiment configured as described above, when the inside of the canister is heated to a high temperature of about 200 ° C., the shape memory alloy of each spacer set shrinks to bring the pair of divided spacers 62a closer to each other. Direction, and press against the second spacer 64. Therefore, the divided spacer 62 and the second spacer 64 that constitute the first spacer of each set include:
The interaction by the wedge shape is pressed against the side surface of the spent fuel assembly 42 and the inner surface of the loading portion 44, respectively.

Therefore, according to the eighth embodiment configured as described above, the rattle of the spent fuel assembly 42 is suppressed by the first and second spacers 62 and 64, and
Even when a large impact acts on the canister 14, the spent fuel assembly 42 can be prevented from being damaged. As a result, it is possible to obtain a canister that can prevent radiation from leaking and can ensure soundness over a long period of time.

In each of the first to eighth embodiments described above, a third spacer for preventing the spent fuel assembly 42 from rattling 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 column shape, a prism shape, or the like, and is welded or bolted to the shielding plate 38. Each of the third spacers 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 the irradiation growth of the spent fuel.

Thus, by providing the third spacer 80 in the axial gap between each spent fuel assembly 42 and the shielding plate 38, the axial play of the spent fuel assembly 42 is reduced. Can be prevented. Therefore, canister 1
Even when a large axial impact is applied to 4, 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. In addition, since the third spacer 80 has a structure that is easily crushed, the third spacer 80 can be crushed and absorb a shock when a large shock acts. Therefore, it is possible to more reliably prevent the spent fuel assembly 42 from being damaged. From the above, it is possible to obtain a canister that can prevent leakage of radiation and can maintain soundness over a long period of time.

The third spacer 80 is not limited to the case where the third spacer 80 is fixed to the shielding plate 38. As shown in FIG.
The spacer may be fixed to the holding plate 82, and the holding plate may be placed on the basket 40.

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.
Welded to. 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 part 44 of the basket 40 and faces the upper end of the spent fuel assembly with a predetermined gap. In addition, each third spacer 8
The upper part of 0 faces the shielding plate 38 with a predetermined gap. Also in such a configuration, the axial play of the spent fuel assembly 42 can be prevented by the third spacer 80, and the same operation and effect as described above can be obtained.

In addition, the present invention is not limited to the above-described embodiment, but can be variously modified 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 needed. Further, although the shapes of the loading portions of the spent fuel assemblies and the baskets are prismatic, the shapes are not limited thereto, and other shapes may be employed as needed.

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

[0059]

As described above in detail, according to the present invention, there is provided a metal hermetically sealed container which can prevent radiation from leaking even when a large impact is applied and can maintain soundness for a long period of time. be able to.

[Brief description of the drawings]

FIG. 1 is a sectional view of a concrete cask provided with a canister according to an embodiment of the present invention.

FIG. 2 is a sectional view taken along the line AA of FIG. 1;

FIG. 3 is a perspective view showing a part of the canister cut away.

FIG. 4 is a sectional view of the canister.

FIG. 5 is a perspective view showing a basket in the canister.

FIG. 6 is a perspective view showing a spent fuel assembly stored in the canister.

FIG. 7 is a plan view and a sectional view showing the basket and the spent fuel assembly, and a perspective view showing a cushioning member.

FIG. 8 is a plan view and a sectional view showing a basket, a spent fuel assembly, and a cushioning member of a canister according to a second embodiment of the present invention.

FIG. 9 is a plan view showing a basket, a spent fuel assembly, and a buffer member of a canister according to a third embodiment of the present invention.

FIG. 10 is a plan view showing a canister basket, a spent fuel assembly, and a cushioning material according to a fourth embodiment of the present invention.

FIG. 11 is a plan view showing a basket, a spent fuel assembly, a spacer, and a pressing member of a canister according to a fifth embodiment of the present invention.

FIG. 12 is a view schematically showing a pressing operation of a spacer in the canister according to the fifth embodiment.

FIG. 13 is a plan view showing a basket, a spent fuel assembly, and a spacer of a canister according to a sixth embodiment of the present invention.

FIG. 14 is a sectional view showing a basket, a spent fuel assembly, and a spacer of the canister according to the sixth embodiment.

FIG. 15 is a plan view showing a basket, a spent fuel assembly, and a spacer of a canister according to a seventh embodiment of the present invention.

FIG. 16 is a plan view showing a basket, a spent fuel assembly, and a spacer of a canister according to an eighth embodiment of the present invention.

FIG. 17 is a cross-sectional view schematically showing a canister according to another embodiment of the present invention having a third spacer.

FIG. 18 is a sectional view schematically showing a canister according to still another embodiment of the present invention having a third spacer.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Concrete cask, 14 ... Canister 15 ... Container main body, 32 ... Primary cover 34 ... Secondary cover, 40 ... Basket 42 ... Spent fuel assembly, 44 ... Loading part 45 ... Fuel rod, 46 ... Top nozzle 50 ... Buffer 51, body 52, engaging claw, 53, through hole 60, cushioning material, 62, first spacer 64, second spacer, 66, pressing member 68, pressing surface, 62a, 64a, split spacer 64b, bimetal, 62b: Shape memory alloy 80: Third spacer

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Kenichi Matsunaga 1-1-1 Wadazakicho, Hyogo-ku, Kobe-shi, Hyogo Inside Mitsubishi Heavy Industries Kobe Shipyard

Claims (15)

[Claims] 1. A substantially cylindrical container main body having a closed lower end, and a basket disposed in the container main body and formed with a plurality of elongated loading portions each extending along the axial direction of the container main body. A radioactive substance aggregate loaded in the loading section and extending along the axial direction of the container main body; a lid closing an upper end opening of the container main body; and a radioactive substance aggregate attached to the radioactive substance aggregate. A metal member for a radioactive substance, comprising: a buffer member located in a radial gap between a body and the basket; and a spacer located in an axial gap between the radioactive substance assembly and the lid. container. 2. The buffer member includes a frame-shaped main body that covers an outer surface of an upper end portion of the radioactive substance aggregate, and an engaging portion extending from the main body and engaged with the radioactive substance aggregate. 2. The metal sealed container for radioactive substances according to claim 1, wherein a plurality of through holes are formed in the through hole to allow the buffer member to be crushed. 3. A basket having a substantially cylindrical container body having a closed lower end, and a plurality of elongated loading portions disposed in the container body and each extending along the axial direction of the container body. A radioactive substance assembly loaded in the loading section and extending along the axial direction of the container body; a lid closing an upper end opening of the container body; and the radioactive substance assembly fitted to the basket. A shock absorbing member extending into a radial gap between the radioactive substance assembly and the basket; and a spacer positioned in an axial gap between the radioactive substance aggregate and the lid. Closed container. 4. The metal sealed container for a radioactive substance according to claim 3, wherein a plurality of the buffer members are provided so as to surround an outer surface of an upper end portion of the radioactive substance assembly. 5. The metal sealed container for a radioactive substance according to claim 3, wherein the buffer member has a plurality of through holes that allow collapse. 6. A basket having a substantially cylindrical container body having a closed lower end, and a plurality of elongated loading portions disposed in the container body and 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 main body; and a plurality of radioactive substance aggregates inserted in the radial direction between the radioactive substance aggregate and the basket in the loading section. A metal-sealed container for radioactive substances, comprising: a pipe-shaped cushioning member; and a lid closing an upper end opening of the container body. 7. The metal sealed container for radioactive substances according to claim 6, wherein each of the buffer members extends in the axial direction of the loading section over substantially the entire length of the loading section. 8. The metal enclosure for radioactive materials according to claim 7, wherein said basket has a plurality of grooves each extending along the inner surface of said loading portion and positioning said buffer member. container. 9. A basket having a substantially cylindrical container body having a closed lower end, and a plurality of elongated loading portions disposed in the container body and each extending along the axial direction of the container body. And a radioactive substance aggregate loaded in the loading section and extending along the axial direction of the container body; and particles filled in a radial gap between the radioactive substance aggregate and the basket in the loading section. A metal-sealed container for radioactive substances, comprising: a shock-absorbing material having a shape of a shell; and a lid closing an upper end opening of the container body. 10. The sealed metal container for a radioactive substance according to claim 9, wherein said buffer material is formed in a hollow spherical shape. 11. A basket having a substantially cylindrical container body having a closed lower end, and a plurality of elongated loading portions disposed in the container body and 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 main body; and the loading section inserted into a radial gap between the radioactive substance aggregate and the basket in the loading section. First and second wedge-shaped spacers arranged so as to overlap with each other in a direction orthogonal to the axial direction of the unit; and fitted to the upper end of the basket, and the first and second spacers are orthogonal to the axial direction of the loading unit. A pressing member that presses in a direction substantially parallel to the inner surface of the loading section and presses the outer surface of the radioactive substance aggregate and the inner surface of the loading section; and a lid that closes an upper end opening of the container body. Metal sealed container for radioactive material having a. 12. A basket having a substantially cylindrical container body having a closed lower end, and a plurality of elongated loading portions disposed in the container body and 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 main body; and the loading section inserted into a radial gap between the radioactive substance aggregate and the basket in the loading section. The wedge-shaped first member is disposed so as to overlap in a direction orthogonal to the axial direction of the portion, and is pressed against the outer surface of the radioactive substance aggregate and the inner surface of the loading portion by sliding each other along the axial direction of the loading portion. And a second spacer, and a lid that closes an upper end opening of the container body. 13. A basket having a substantially cylindrical container body having a closed lower end, and a plurality of elongated loading portions disposed in the container body and 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 main body; a spacer unit inserted into a gap between the radioactive substance aggregate and the basket in the loading section; A lid closing the upper end opening of the container body, wherein the spacer unit has a first spacer positioned on the radioactive substance aggregate side and a second spacer positioned on the inner surface side of the loading section; 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, and is arranged in accordance with a temperature change. And a pressing member for moving the split spacer and pressing the split spacer against the other of the first and second spacers. 14. The sealed metal container for radioactive substances according to claim 13, wherein the pressing member is formed of a bimetal. 15. The metal sealed container for radioactive substances according to claim 13, wherein said pressing member is formed of a shape memory alloy.