JP2001201594A - Cask - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the drainability of a double seal arranged between a cask body and a shielding body. SOLUTION: This cask comprises a primary lid 31 or secondary lid 32 for shielding the opening of the cask body for housing a spent nuclear fuel assembly; and annular double O-ring 10 arranged between the cask body and the primary lid 31 or secondary lid 32; a pressure air port 40 extending from the primary lid 31 or secondary lid 32 to the double O-ring 10 to inject pressurized air to the internal space of the double O-ring 10; a drain port 50 for draining the liquid pushed out by the pressurized air; and a soft metal 20 for forming a sealed wall in the internal space of the double O-ring 10, which regulates the route of the pressurized gas from the pressure air port 40 to the drain port 50 to a prescribed route. Since the inflow route of the pressurized air is regulated to the one route by this soft metal 20, the drainabilitiy of the double O-ring is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cask for storing a spent nuclear fuel assembly having finished fuel, and more particularly to draining water or the like that has entered a double seal provided on a lid or the like. About the cask.

[0002]

2. Description of the Related Art A nuclear fuel assembly that has been burned at the end of a nuclear fuel cycle and has become unusable is called spent nuclear fuel. Since this spent nuclear fuel generates radioactivity and decay heat including fissile materials and fission products, it must be thermally cooled, and is used for a predetermined period (for example, 3 hours) in a cooling pit of a nuclear power plant.間 6 months). Thereafter, the spent nuclear fuel is stored in a cask, which is a shielding container for radioactivity, transported to a reprocessing facility or the like by a truck or the like, and stored for a long time in a predetermined storage room.

[0003] As a conventional example of such a cask,
Various types are disclosed in "Atomic energy eye" (published on April 1, 1998: Nikkan Kogyo Shuppan Production), Japanese Patent Application Laid-Open No. 62-242725, and the like. In the following, a cask which is a premise for developing the present invention will be described. In addition, the said cask is shown for convenience of explanation, and does not correspond to what is called a well-known and public use.

FIG. 12 is an exploded perspective view of a conventional cask, FIG. 13 is a plan view of a primary lid or a secondary lid, FIG. 14 is a longitudinal sectional view of a bolt portion of the lid, and FIG. FIG. 16 is a conceptual diagram showing a drain state of the double O-ring. As shown in FIG.
Comprises a cylindrical cask body 2, a lid 3 at one end, and a bottom 4 at the other end. As shown in a broken portion in FIG. 12, the outer peripheral portion of the cask main body 2 is covered with a resin 5 which is a neutron shield, and a plurality of square pipes 6 containing spent nuclear fuel are bundled inside the resin. And a basket 7 configured as a group.

[0005] The cask body 2 and the bottom 4 are forged products made of carbon steel, which is a γ-ray shield. The lid 3 is made of a disc-shaped primary lid 31 and a secondary lid 32 made of stainless steel or the like.
It is composed of As shown in FIG. 14, the primary lid 31 and the secondary lid 32 are provided with flanges 31a around the periphery thereof,
Each is fixed to the upper part of the cask main body 2 by a bolt 33 penetrating through 32a. A metal double O-ring 10 is sandwiched between the primary lid 31 and the secondary lid 32 and the cask main body 2 as a sealing material for maintaining the airtightness therebetween.

As shown in FIGS. 13 to 15, the bottoms of the flanges 31a and 32a of the primary lid 31 and the secondary lid 32 are
Along the entire circumference of the flanges 31a, 32a
b, 32b are formed, and the concave portions 31b, 32b
A double O-ring 10 is housed therein. As shown in FIG. 15, the double O-ring 10 has a pair of O-rings 11.
Are connected to each other via a connecting piece 12 to form an integral double O-ring. An inner space 13 is formed between the pair of O-rings 11, and the double O-ring 10 is fixed to the primary lid 31 or the secondary lid 31 by a fixing screw 14 penetrating the connecting piece 12 through the internal space 13. 32.

The double O-ring 10 has two O-rings.
A stand-alone type in which the ring 11 is arranged in an individual concave portion in a non-connected state has also been proposed. However, the integral double O-ring 10 is easier to handle than the standalone double O-ring 10 because the two O-rings 11 can be fixed together or the like. Further, the connection piece 12 can be securely fixed by screwing it to the primary lid 31 or the secondary lid 32, and it is necessary to remotely attach the lid 3 without approaching the cask 100. This integrated double O-ring 10 is mainly used for the cask 100 because it is suitable under certain circumstances.

Here, the storage of the spent nuclear fuel in the cask body 2 is performed in pure water to suppress the reaction of the spent nuclear fuel. Schematically, first, the cask main body 2 before attaching the lid 3 is arranged in a storage pool filled with pure water, and spent nuclear fuel is inserted into the cask main body 2. Thereafter, the primary lid 31 with the double O-ring 10 attached thereto is lifted by a crane, covered on the upper part of the cask main body 2, and fixed with bolts 33.

After the airtightness of the cask body 2 is confirmed, the cask body 2 is lifted from the storage pool. Further, the secondary lid 32 with the double O-ring 10 attached thereto is lifted by a crane, and
And is fixed with bolts 33. Then, the airtightness of the cask main body 2 is confirmed again. Confirmation of the airtightness is performed by detecting the peripheral pressure of the double O-ring 10 with a sensor (not shown) provided on the primary lid 31 and the secondary lid 32, and determining whether a fluctuation value of the detected pressure is equal to or less than a predetermined value. Is performed on the basis of

As described above, since the mounting of the primary lid 31 is performed in pure water, and the secondary lid 32 is also mounted soon after being pulled out of the storage pool, the internal space 13 of the double O-ring 10 Water will accumulate. When water accumulates in the double O-ring 10 as described above, the pressure inside the double O-ring 10 greatly fluctuates due to the volume fluctuation of the water. There is a problem that the fluctuation value is detected to be equal to or more than a predetermined value, and the sealing standard cannot be cleared.

In order to solve such a problem, the cask 100 is provided with a mechanism for draining water that has entered the double O-ring 10. Specifically, FIG.
As shown in (1), a pair of compressed air port 101 and a drain port 102 reaching the internal space 13 were provided on the flanges 31a and 32a of the primary lid 31 and the secondary lid 32, respectively. The compressed air port 101 and the drain port 10
Numerals 2 are formed at positions opposing each other, and pressurized air is injected from a compressed air port 101, and the water that has entered the double O-ring 10 is pushed out by this pressure, and can be drained from a drain port 102.

[0012]

However, in the conventional cask, the compressed air port 101 and the drain port 102 are simply provided at the opposed positions as described above.
As shown in FIG. 16, two routes R100 and R10 are provided as routes from the compressed air port 101 to the drain port 102.
1 had been formed. Therefore, for example, the pressure O injected from the compressed air port 101 flows only into the route R100, and the water in the route R101 is not drained.
There is a possibility that the water that has entered the ring 10 cannot be sufficiently drained.

The present invention has been made in view of the above, and can improve drainage of water or the like that has entered a double seal disposed between a cask main body and a shield. The purpose is to provide a cask.

[0014]

In order to achieve the above object, a cask according to claim 1 comprises a cask main body for storing a spent nuclear fuel assembly, and a shielding body for shielding an opening of the cask main body. , An annular double seal disposed between the cask body and the shield, and a pressurized air port that injects pressurized gas into the internal space of the double seal from the shield to the double seal, and A drain port for draining the liquid extruded by the pressurized gas and a closed wall in the inner space of the double seal are formed, and the path of the pressurized gas from the pressurized air port to the drain port is a predetermined one path. A regulating sealing member.

Since the double seal has an internal space, a liquid such as water may enter the internal space. Pressurized gas such as pressurized air injected from a compressed air port to drain the water or the like flows into the internal space of the double seal via the compressed air port. Here, since the flow of the pressurized gas in the internal space is regulated by the sealing wall provided in the internal space, the flow path of the pressurized gas is limited to one predetermined path. Therefore, the pressurized gas flows only into the predetermined one path, and the liquid stored in the internal space is pushed out along the same path and drained from the drain port. As described above, since the pressurized gas does not flow into the plurality of paths, the liquid stored in the internal space can be reliably drained, and the drainage property can be improved.

In the cask according to the second aspect, the shield may be a lid for shielding an opening provided in the cask main body for accommodating the spent nuclear fuel assembly.

The present invention can be applied to a closed structure between an arbitrary opening provided in a cask main body and an arbitrary shielding body such as a lid for shielding the opening.
In particular, since the storage of the spent nuclear fuel assembly in the cask body is performed in a pure state, water easily accumulates between the opening for this storage and the lid that shields this opening. Further, since the sealing property of the lid is extremely important to prevent the diffusion of neutrons and the like radiated from the spent nuclear fuel assembly, it is necessary to drain water to enhance the sealing property. By performing reliable drainage in such a portion, the reliability of the entire cask can be improved.

According to a third aspect of the present invention, there is provided a cask, wherein a sealing member is provided at one of the entire circumferences of the double seal, and a compressed air port is formed at one of two adjacent positions with respect to the sealing member. A drain port is formed at the other of the two adjacent positions.

The pressurized gas injected from the compressed air port can flow only in the direction opposite to the sealing member. The pressurized gas flowing in this direction reaches the vicinity of the sealing member again while pushing out the liquid accumulated in the internal space. The extruded liquid is prevented from flowing into the compressed air port side by the sealing member,
It is drained from the drain port located in front of it. As described above, since drainage can be performed only by providing one sealing member, one compressed air port, and one drainage port, it is easy to manufacture a lid and a double seal, and to inject pressurized air.

According to a fourth aspect of the present invention, in the cask, the sealing member is provided at substantially two opposing positions in the entire circumference of the double seal, and compressed air ports are formed at both two adjacent positions with respect to one sealing member. In addition, drain ports are formed at both two adjacent positions with respect to the other sealing member.

The pressurized gas injected from the two compressed air ports can flow only in the direction opposite to the sealing member. The pressurized gas flowing in this direction reaches the vicinity of the sealing member on the opposite side while pushing out the liquid accumulated in the internal space. The extruded liquid is prevented from proceeding further by the sealing member, and is drained from a drain port located in front thereof. Since the two drainage paths formed here are as short as substantially half the circumference of the lid, drainage can be performed more quickly than when drainage is performed through the entire circumference. Further, since the pressure required for pushing water is reduced by the shorter path length, the pressure of the pressurized air can be reduced. Furthermore, the two drain passages are formed independently of each other by the two sealing members, and since the gas or liquid in one passage does not flow into the other passage, the pressure of the gas injected into the two passages is increased. Does not reduce drainage even if is imbalanced.

The cask according to claim 5 is such that the sealing member is formed of a soft metal.

The sealing member sandwiched between the cask body and the shield is pressed from the cask body and the like. Here, since the sealing member is formed of a soft metal, the sealing member has an elastic force. When pressed, the sealing member is elastically deformed by its own elastic force, and closes a gap between the cask body and the like to seal. Improve the performance. In particular, when a metal having corrosion resistance such as gold is used, the hermeticity during a long storage period can be more reliably maintained.

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of a cask according to the present invention will be described below in detail with reference to the drawings.
However, the present invention is not limited by the embodiment.

FIG. 1 is a perspective view of a cask according to a first embodiment of the present invention, FIG. 2 is a longitudinal sectional view of the cask of FIG. 1, and FIG. 3 is an exploded perspective view of the cask of FIG. is there. The configuration that is not particularly described is the same as the above-described conventional technology, and the same configuration is denoted by the same reference numeral.

As shown in FIGS. 1 to 3, the cask 1 comprises a cylindrical cask main body 2, a lid 3 at one end, and a bottom 4 at the other end. Cask body 2
Is covered with a resin 5 which is a neutron shield, and a basket 7 formed by collecting a plurality of square pipes 6 for storing used nuclear fuel in a bundle is provided inside the resin. I have.

The cask main body 2 and the bottom part 4 are forged products made of carbon steel as a γ-ray shield, and are joined by butt welding. The lid 3 is made up of a disc-shaped primary lid 31 and a secondary lid 32 made of stainless steel or the like. The primary lid 31 and the secondary lid 32 are made of a plurality of stainless steels that penetrate through peripheral flanges 31a and 32a. The bolts 33 are fixed to the upper part of the cask main body 2 (the flanges 31a and 32a in FIGS. 1 and 2).
Are covered by the auxiliary shield 8).

FIG. 4 is an exploded perspective view showing the primary lid or the secondary lid and the like from below, FIG. 5 is a plan view of the primary lid or the secondary lid, FIG. 6 is a longitudinal sectional view of a bolt portion of the lid, and FIG. FIG. 8 is a vertical cross-sectional view at the compressed air port portion of the lid, and FIG. 8 is a vertical cross-sectional view at the double O-ring portion of the lid. As shown in FIGS.
A metal double O-ring 10 is sandwiched between the primary lid 31 and the secondary lid 32 and the cask main body 2 as a sealing material for maintaining the airtightness therebetween. As shown in FIGS. 4 and 8, the flanges 31 a and 32 a of the primary lid 31 and the secondary lid 32
The recesses 31b and 32b are formed along the entire periphery of the recesses 31a and 32a, and the recesses 31b and 32b are formed in the recesses 31b and 32b.
An annular double O-ring 10 substantially corresponding to b and 32b is stored.

As shown in FIG. 8, the double O-ring 10 is an integrated double O-ring in which a pair of O-rings 11 made of metal such as stainless steel are connected to each other via a connecting piece 12. An internal space 13 is formed between the pair of O-rings 11, and the double O-ring 10 is fixed to the primary lid 31 or the secondary lid 31 by a fixing screw passing through the internal space 13 and penetrating the connecting piece 12. 32.
In this state, the upper end of each O-ring 11 is
The lower end of each O-ring 11 abuts on the upper surface of the cask main body 2 to maintain the airtightness between the primary lid 31 or the secondary lid 32 and the cask main body 2.

Each O-ring 11 contains a metal or the like for maintaining the elasticity of the O-ring 11.
In addition, various double O-rings such as a double O-ring in which an elastic body such as a spring is further housed inside a metal or the like can be adopted. Further, the cross-sectional shape of each O-ring 11 is not limited to a circle, but may be an arbitrary shape such as an ellipse. That is, a pair of O-rings 11 are connected to each other via the connecting piece 12, and all double O-rings having the internal space 13 between the respective O-rings 11 may be used.

The double O-ring 10 is preferably fixed to the primary lid 31 or the secondary lid 32 for protection of the double O-ring 10 as described above, but this fixing structure can be changed as appropriate. For example, it can be attached to the upper surface of the cask main body 2.

Here, as shown in FIGS. 5 and 8, a soft metal 20 as a sealing member is provided at one position on the entire circumference of the double O-ring 10. This soft metal 20
As shown in FIG. 8, a rectangular block having a longitudinal sectional shape substantially adapted to the internal space 13, and the upper surface thereof is connected to the connecting piece 1.
2, the side surfaces of which contact the O-rings 11, and the lower surfaces of which contact the upper surface of the cask body 2, thereby restricting the flow of gas and liquid in the internal space 13. It functions as a closed wall. However, the hermeticity of the soft metal 20 may not be perfect, and the inside of the internal space 13 may be drained so that a liquid such as water that has entered the inside of the double O-ring 10 can be drained to a desired degree. Any material can be used as long as it can regulate the flow of gas such as compressed air and liquid such as water to some extent.

In order to obtain such watertightness, soft metal 2
As 0, specifically, it is preferable to use a metal having elasticity, such as gold or silver. As a matter of course, it is preferable to use a metal having corrosion resistance as the soft metal 20, and gold and the like are also preferable in this regard. However, an arbitrary sealing member such as a synthetic resin can be used instead of the soft metal 20. The shape of the soft metal 20 is not limited to the above-described rectangular block, but may be the internal space 1.
3 may be formed as a deformed shape that is more suitable for the vertical cross-sectional shape. Further, the watertightness may be improved by providing an elastic body such as a spring inside the soft metal 20.

The soft metal 20 comprises a double O-ring 10,
It is fixed to the primary lid 31 or the secondary lid 32 and has at least a compressed air port 40 and a drain port 50 described later.
Is maintained relative to. Various fixing structures may be employed. For example, a fixing screw penetrating the soft metal 20 from below may be connected to the connecting piece 12,
It can be fixed by screwing it into the primary lid 31 or the secondary lid 32. Alternatively, a rib piece is provided on the side of the soft metal 20, and a fixing screw penetrating the rib piece is
It can be fixed by screwing it into the connecting piece 12, the primary lid 31, or the secondary lid 32. Further, when the double O-ring 10 is fixed to the cask main body 2, the soft metal 20 can also be fixed to the cask main body 2.

Here, as shown in FIG. 5, a compressed air port 40 is formed at one of two adjacent positions to the soft metal 20. Compressed air port 40
As shown in FIG. 7, is a through hole that penetrates the primary lid 31 or the secondary lid 32 and reaches the internal space 13 of the double O-ring 10. The supplied pressurized air is caused to flow into the internal space 13 of the double O-ring 10. The compressed air port 40 only needs to function as a path for injecting pressurized air into the internal space 13, and its shape, the position of air injection, and the like can be appropriately changed. For example, pressurized air may flow from the side instead of above the primary lid 31 and the secondary lid 32.

As shown in FIG. 5, a drain port 50 is formed at the other of the two adjacent positions to the soft metal 20. This drain port 50
Is a through hole that penetrates through the primary lid 31 or the secondary lid 32 and reaches the internal space 13 of the double O-ring 10 like the compressed air port 40. When the pressurized air injected through the pressurized air port 40 flows into the internal space 13 of the double O-ring 10 and the water accumulated in the internal space 13 is pushed out by the pressurized air, , This water into the primary lid 31
Alternatively, it functions as a drainage path for draining outside the secondary lid 32.

The drain port 50 only needs to function as a path for draining water in the internal space 13 to the outside of the primary lid 31 or the secondary lid 32, and the shape, the injection position of air, and the like are appropriately changed. be able to. The compressed air port 40 and the drain port 50 are arranged as close as possible to the soft metal 20 so that the soft metal 20
It is desirable to form so that water does not accumulate between them.

A procedure for draining water that has entered the internal space 13 of the double O-ring 10 through the compressed air port 40 and the drain port 50 will be described. FIG. 9 is a conceptual diagram showing a drained state of the double O-ring. First, pressurized air is injected from the compressed air port 40, and the pressurized air flows into the internal space 13. Here, as shown in FIG. 9, since the compressed air port 40 is adjacent to the soft metal 20, the inflow of pressurized air to the drain port 50 side is restricted by the soft metal 20, and the compressed air is 20 can flow only in the opposite direction (the direction of the arrow in FIG. 9).

Accordingly, the pressurized air flows only in the direction of the arrow in FIG. 9 while pushing water, and the pushed water reaches the vicinity of the soft metal 20. The flow of the water extruded into the compressed air port 40 side is regulated by the soft metal 20, and the water is drained from the drain port 50 located in front of the soft metal 20. That is, the soft metal 2
By providing 0, the flow path of the pressurized air is limited to only one path R1, and water is reliably drained through this path R1. In particular, according to the present embodiment, reliable drainage can be performed only by providing one each of the soft metal 20, the compressed air port 40, and the drainage port 50, so that the production of the lid 3 and the double O-ring 10, It is easy to inject pressurized air.

(Embodiment 2) FIG. 10 is a plan view of a primary lid or a secondary lid, and FIG. 11 is a conceptual view showing a drained state of a double O-ring. The configuration that is not particularly described is the same as that of the first embodiment, and the same configuration is denoted by the same reference numeral. As shown in FIG. 10, in the present embodiment, the primary lid 31
And two compressed air ports 41, 4 on the periphery of the secondary lid 32.
2, and two drain ports 51, 52 are formed, and the double O-ring 10 has two soft metals 21,
22 are provided.

The two soft metals 21 and 22 are provided at locations substantially opposite to each other in the entire circumference of the double O-ring 10, as in the first embodiment. It is arranged in the space 13 and functions as a sealing wall that regulates the flow of gas and liquid in the internal space 13.
In addition, the compressed air ports 41 and 42 are provided at both two adjacent positions to one soft metal 21, and the drainage ports 51 and 52 are provided at both two adjacent positions to the other soft metal 22. I have. In other words, the two compressed air ports 41 and 42 are juxtaposed at a slight interval, the soft metal 21 is arranged between them, and the two drainage ports 51 and 52 are juxtaposed at a slight interval. And the soft metal 22 is disposed therebetween.

Therefore, as shown in FIG. 11, when pressurized air is injected from both the compressed air ports 41 and 42,
The pressurized air from the compressed air port 41 can flow only into the path R2 extending in the opposite direction to the soft metal 21, and at the same time,
Pressurized air from the compressed air port 42 can flow only into the path R3. Therefore, the pressurized air passes through the route R2,
The water flowing into R3 and accumulated inside each of the routes R2 and R3 is pushed out, the water in the route R2 is drained from the drain port 51, and the water in the route R3 is drained from the drain port 52. Also in this case, the flow path of the pressurized air from the compressed air port 41 and the flow path of the pressurized air from the compressed air port 42 are limited to different paths R2 and R3, respectively. Water is reliably drained through R3.

In particular, the length of each of the routes R2 and R3 is
Since it is as short as approximately half the circumference of the first or secondary lid 32, it is possible to perform quick drainage, and it is possible to reduce the pressure of the pressurized air by an amount corresponding to the short path length. It should be noted that substantially the same effect can be obtained even if the soft metal 22 on the drain ports 51 and 52 is omitted and one of the drain ports 51 and 52 is omitted. However, in this case, if the pressures of the routes R2 and R3 are mutually imbalanced, the route R
The configuration shown in FIG. 10 is more preferable because one of the waters R2 and R3 may flow into the other routes R2 and R3 through the drain port.

In addition to what has been described above, the present invention can be implemented in various different forms. For example, in the above description, the primary lid 31 and the secondary lid 32 and the cask body 2
The closed structure between the main body and the cask main body 2
The above-described structure can be similarly applied to a sealed structure between an arbitrary opening provided in the above and an arbitrary shielding member that shields this opening. Also, the gas injected into the double O-ring 10 is described as air, and the liquid drained from the double O-ring 10 is described as water. However, the present invention can be applied to any drainage structure that drains any liquid with any gas. it can.

[0045]

As described above, according to the cask according to the present invention (claim 1), the pressurized air port for injecting pressurized gas into the inner space of the double seal and the pressurized gas are used to push out. Forming a closed wall in the internal space of the double seal, and a sealing member or the like for restricting the path of the pressurized gas from the compressed air port to the drain port to one predetermined path. Therefore, the pressurized gas does not flow into a plurality of paths, so that the liquid stored in the internal space can be reliably drained, and the drainage property can be improved.

According to the cask according to the present invention (claim 2), the shield is a cover for shielding the opening provided in the cask main body for accommodating the spent nuclear fuel assembly. Therefore, water easily accumulates when the spent nuclear fuel assemblies are stored, and reliable drainage is performed at a site important for preventing the diffusion of neutrons and the like, so that the reliability of the entire cask can be improved.

According to the cask according to the present invention (claim 3), the sealing member is provided at one position on the entire circumference of the double seal, and the compressed air port is provided at one of two adjacent positions with respect to the sealing member. Since the drainage port is formed at the other of the two adjacent positions with respect to the sealing member, drainage can be performed only by providing one sealing member, one compressed air port, and one drainage port. Manufacturing and injection work of pressurized air are easy.

Further, according to the cask according to the present invention (claim 4), the sealing member is provided at two substantially opposing positions in the entire circumference of the double seal, and both of the two adjacent positions with respect to one sealing member are provided. Since the compressed air port is formed in each of the airtight ports and the drainage ports are formed in both of the two adjacent positions with respect to the other sealing member, the drainage can be performed more quickly. Further, the pressure of the pressurized air can be reduced. Furthermore, even if the pressurized pressure of the gas injected into the two paths is imbalanced, the drainage performance is not reduced.

Further, since the cask according to the present invention (claim 5) is formed of a soft metal, the soft metal is elastically deformed by its own elastic force, and the gap between the cask body and the like is reduced. Improves sealing by closing.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a configuration of a cask according to a first embodiment of the present invention.

FIG. 2 is a longitudinal sectional view showing a configuration of a cask shown in FIG.

FIG. 3 is an exploded perspective view showing the configuration of the cask shown in FIG.

FIG. 4 is an exploded perspective view showing a primary lid, a secondary lid, and the like from below.

FIG. 5 is a plan view showing a primary lid or a secondary lid.

FIG. 6 is a longitudinal sectional view of a bolt portion of the lid.

FIG. 7 is a longitudinal sectional view at a compressed air port portion of the lid.

FIG. 8 is a longitudinal sectional view of a double O-ring portion of the lid.

FIG. 9 is a conceptual diagram illustrating a drained state of a double O-ring.

FIG. 10 is a plan view showing a configuration of a primary lid or a secondary lid of a cask according to a second embodiment of the present invention.

FIG. 11 is a conceptual diagram illustrating a drained state of a double O-ring.

FIG. 12 is an exploded perspective view showing a configuration of a conventional cask.

FIG. 13 is a plan view showing a configuration of a primary lid or a secondary lid.

FIG. 14 is a longitudinal sectional view of a bolt portion of the lid.

FIG. 15 is a longitudinal sectional view of a double O-ring portion of the lid.

FIG. 16 is a conceptual diagram showing a drained state of a double O-ring.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1, 100 Cask 2 Cask main body 3 Lid 4 Bottom 10 Double O-ring 11 O-ring 12 Connecting piece 13 Internal space 20, 21, 22 Soft metal 31 Primary lid 32 Secondary lid 33 Bolt 40, 41, 42, 101 Compressed air Port 50, 51, 52, 102 Drainage port

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G21F 9/36 501

Claims (5)

[Claims] 1. A cask main body for storing a spent nuclear fuel assembly, a shield for shielding an opening of the cask main body, an annular double seal disposed between the cask main body and the shield, From the body to the double seal, a pressurized air port that injects pressurized gas into the internal space of the double seal, a drain port that drains the liquid pushed out by the pressurized gas, and the inside of the double seal And a sealing member that forms a closed wall in the space and regulates the path of the pressurized gas from the compressed air port to the drain port to one predetermined path. 2. The cask according to claim 1, wherein the shield is a lid that shields an opening provided in the cask main body for accommodating the spent nuclear fuel assembly. 3. A sealing member is provided at one position on the entire circumference of the double seal, a compressed air port is formed at one of two adjacent positions with respect to the sealing member, and drainage is formed at the other of two adjacent positions with respect to the sealing member. 3. The cask according to claim 1, wherein a port is formed. 4. A sealing member is provided at substantially two opposing positions in the entire circumference of the double seal, and compressed air ports are formed at both of two adjacent positions with respect to one sealing member, and two sealing members with respect to the other sealing member are formed. 3. The cask according to claim 1, wherein drain ports are formed at both of two adjacent positions. 5. The cask according to claim 1, wherein the sealing member is formed of a soft metal.