JP2002156494A - Cask - Google Patents

Abstract

PROBLEM TO BE SOLVED: To omit work for replacing metal gasket with an O-ring. SOLUTION: Into a bolt hole 12 machined with a taper, a taper sleeve 15 is inserted. A primary lid 4 is fixed to a flange part 2 of a shell body 1 through the cylinder of the taper sleeve 15. Also, a taper sleeve 23 is inserted in a bolt hole 20 machined with a taper and a secondary lid 7 is fixed to the flange part 2 of the shell body 1 through the cylinder of the taper sleeve 23. With this method, radial motion of the primary lid 4 and the secondary lid 7 is a disturbed and sliding of the metal gasket 6 and 10 is prevented. Thus, a cask 100 can be transported only with metal gaskets 6 and 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure vessel for storing a burned spent fuel assembly, and relates to a cask in which replacement of a metal gasket can be omitted.

[0002]

2. Description of the Related Art At the end of a nuclear fuel cycle, a nuclear fuel assembly that has been burned and becomes unusable is called a spent fuel assembly. Spent fuel assemblies contain high radioactive materials such as FP and need to be thermally cooled. Therefore, the spent fuel assemblies are cooled in a cooling pit of a nuclear power plant for about 60 years. afterwards,
It is stored in a cask, which is a shielding container, and transported and stored in a reprocessing facility by truck or the like. Since the cask contains a highly radioactive substance, strict caution is required for sealing the cask.

FIG. 7 is a sectional view showing the structure of a conventional cask. FIG. 8 is a partially enlarged view of the cask shown in FIG. The cask 500 includes a body 501 made of stainless steel or carbon steel, an outer cylinder 502 constituting an outer surface of the cask, and a resin material of a polymer material containing hydrogen filled between the body 501 and the outer cylinder 502. 503, a bottom plate 505 welded to the lower part of the trunk body 501 and enclosing a resin 504, and a primary lid 507 and a secondary lid 508 provided on a flange part 506 welded and integrated with the trunk body 501. . The basket 513 for storing the spent fuel assemblies is arranged in the cavity 509 of the trunk body 501. As shown in FIG. 8, the primary lid 507 and the secondary lid 508 are fixed to the flange 506 by bolts 510 and 511, and a resin 512 is sealed in the secondary lid 508.

The basket 513 includes a plurality of cells formed of a composite material of boron (B) and aluminum. The cavity 509 of the cask 500 is filled with helium gas under a negative pressure, while the space between the primary lid 507 and the secondary lid 508 has a positive pressure. To form a pressure barrier. Also, the secondary lid 508
Is provided with a hole 514 for measuring the pressure in the space between the lids.
5 are provided.

The primary lid 507 is provided with a valve 516 for performing gas replacement in the cask, and the valve 516 is covered by a valve cover 517. Between the primary lid 507 and the trunk body 501, the secondary lid 508
For sealing between the body and the body 501, metal gaskets 518 and 519 having high heat resistance, corrosion resistance and high durability are used from the viewpoint of maintaining the sealing function for a long period of time.

FIG. 9 is an enlarged view showing a seal portion of a cask. The seal between the primary cover 507 and the body 501 and between the secondary cover 508 and the body 501 have the same seal structure. The seal groove 520 is formed by machining, and the metal gaskets 518 and 519 used have a double inner and outer ring structure. This metal gasket 5
18, 519 are coated with a coil spring 521 made of Inconel (a nickel-based alloy containing 16% chromium and 7% iron) resistant to corrosion and high-temperature oxidation with an inner envelope 522 also made of Inconel.
In this configuration, the inner and outer rings are collectively covered with an outer envelope 523 made of aluminum.

[0007] The seal groove 520 is fixed using bolt holes provided in the outer envelope 523. The metal gaskets 518 and 519 include, for example, “Triback” manufactured by Nippon Valqua Industries, Ltd., and CEFILA of France, which have been used in many nuclear casks.
“Helicflex seal” manufactured by Company C can be used.

The temperature and time dependence of the plastic deformation rate and sealing performance of a metal gasket are determined by the Larson-Miller Parameter (LMP).
For details, see "Development of a long-term sealing performance evaluation method for spent fuel storage casks" (Kato, Ito, Saegusa, Journal of the Atomic Energy Society of Japan, Vol. 38, No. 6, 95-
101, 1996). Generally, the long-term sealing performance of a metal gasket requires the LMP of the sealing retention limit,
This is performed by estimating a limit time at a predetermined temperature.

An O-ring groove 524 into which an O-ring made of synthetic rubber is fitted is machined on the inner peripheral side of the metal gaskets 518, 519. Normally, when storing the cask 500, an O-ring made of synthetic rubber is not used. The reason for not using a synthetic rubber O-ring during storage is that high temperature (150
This is because it cannot withstand use under high-dose conditions.

On the other hand, the metal gaskets 518 and 519
Unsuitable for use in cask transport for the following reasons. When the metal gaskets 518 and 519 are used, the leakage rate (1 × 10 ⁻⁹ Pa · m ³ /
s), the displacement between the secondary lid 508 and the trunk body 501 is limited to about 0.2 mm to 0.3 mm, but the displacement when the cask 500 is actually dropped is several mm,
They differ by almost one digit. Therefore, the metal gasket 51
8 and 519 may fall below the recommended value when the cask 500 is dropped. Therefore, in the conventional cask 500, the metal gasket 518 of the secondary lid 508 is attached to the synthetic rubber O-ring during transportation. The cask had to be transported after being replaced.

On the other hand, synthetic rubber O-rings
It has been confirmed that a sufficient sealing function can be maintained even for a few months (transportation period) even at a high temperature and a high dose, even for a lateral displacement due to a drop.

[0012]

The above conventional cask 5
In 00, to replace the metal gasket 518 and the synthetic rubber O-ring, once remove the secondary lid 508,
It is necessary to mount an O-ring in the O-ring groove 524 of the secondary lid 508. Then, the secondary lid 508 is attached to the cask again, and then the security inspection is performed. In addition, since all these operations are performed under a high dose, the cask 500
Must be performed in the pool. Alternatively, the cask 50 is placed in a hot cell surrounded by a thick shielding wall.
0 must be installed and performed remotely.
For this reason, in the conventional cask 500, there is a problem that the replacement work of the seal is troublesome and costly.

In view of the above, the present invention has been made in view of the above, and provides a cask in which the metal gasket is devised so that the cask can be transported and stored, so that the metal gasket replacement work can be omitted. The purpose is to do.

[0014]

According to a first aspect of the present invention, there is provided a cask according to the first aspect, wherein a cavity with a bottom is formed in a trunk body for shielding gamma rays, and a spent fuel is formed in the cavity. Put a basket to store the assembly,
In a cask in which a lid is attached to the cavity opening side of the trunk main body and a metal gasket is interposed between an end of the trunk main body and a peripheral edge of the lid to maintain a seal in the cavity, a peripheral portion of the lid extends from the peripheral edge of the lid. A continuous pin hole is provided over the end of the pin, and a pin is inserted into the pin hole.

By stopping the trunk body and the lid with the pin, even if the lid attempts to move when the cask falls, the lid is prevented by the shear stress of the pin, so that the lateral displacement of the metal gasket is prevented. The pins include a parallel pin and a tapered pin.

According to a second aspect of the present invention, there is provided a cask, wherein a bottomed cavity is formed in a trunk body for shielding gamma rays, and a basket for storing a spent fuel assembly is accommodated in the cavity. In a cask that attaches a lid to the cavity opening side and interposes a metal gasket between the end of the trunk body and the peripheral edge of the lid to maintain the seal in the cavity, from the peripheral edge of the lid to the end of the trunk body It is characterized in that a continuous tapered hole is provided, and a tapered pin is inserted into the tapered hole.

As described above, even when the taper pin is used, it is possible to prevent the lid from moving when the cask falls, and to prevent the metal gasket from laterally shifting. In particular, by using the tapered pin, the positional relationship between the lid and the trunk body can be reliably restricted.

According to a third aspect of the present invention, there is provided a cask, wherein a bottomed cavity is formed in a trunk body for shielding γ-rays, a basket for storing a spent fuel assembly is accommodated in the cavity, and a cavity is provided on the cavity opening side. A plurality of bolt holes are provided in the peripheral portion of the lid to be provided, and the lid is bolted to the end of the cavity opening side with the bolt holes, and a metal gasket is interposed between the end of the trunk body and the lid so that the inside of the cavity is formed. In the cask for maintaining the sealing of the bolt, the bolt hole through which the bolt passes is formed in a tapered shape continuous from the periphery of the lid to the end of the trunk body, and a tapered sleeve is inserted into the tapered bolt hole and the tapered sleeve is inserted. Characterized in that the body and the lid are bolted to each other by passing the bolt through the cylinder. If the tapered sleeve is provided using the bolt hole as described above, it is not necessary to separately provide a pin hole.

According to a fourth aspect of the present invention, there is provided a cask, wherein a bottomed cavity is formed in a trunk body for shielding gamma rays, and a basket for storing a spent fuel assembly is accommodated in the cavity. In a cask that attaches a lid to the cavity opening side and interposes a metal gasket between the end of the trunk body and the peripheral edge of the lid to maintain the seal in the cavity, from the peripheral edge of the lid to the end of the trunk body A continuous pin hole is provided, and the female screw is cut while leaving the pin hole in the pin hole on the trunk body side.A shaft portion of the bolt is fitted into the pin hole, and a screw portion of the bolt is screwed into the female screw. It is characterized by being screwed.

As described above, the same function as the above-mentioned pin can be achieved by using the shaft of the bolt. That is, a female screw is cut in the pin hole on the trunk body side, a bolt is passed from the pin hole on the lid side to the pin hole on the trunk body side, and the shaft of the bolt is located in the pin hole, so that the pin is substantially in contact with the pin. It will have a similar function. Then, by screwing the screw portion of the bolt to the female screw, the lid and the body can be connected.

According to a fifth aspect of the present invention, in the above-mentioned cask, the maximum clearance between the shaft of the pin or the bolt and the pin hole or the maximum clearance between the tapered hole and the tapered pin or the tapered sleeve is further provided. The metal gasket is set to an allowable shift amount or less.

For example, in the case of a pin and a pin hole, the maximum clearance according to the standard is determined from their tolerance. However, this pin is used for the purpose of preventing lateral displacement of the metal gasket. If so, the movement of the lid can be restricted to the maximum clearance of the pin, so that the object can be achieved.

According to a sixth aspect of the present invention, in the above-mentioned cask, the fixed portion formed by the pin or the shaft of the pin or the bolt or the fixed portion formed by the tapered hole and the tapered pin or the tapered sleeve is formed by a pin,
The number of bolts to be used is determined based on the shear strength of the bolt shaft or the tapered sleeve, and these are arranged substantially evenly around the lid to fix the lid and the body. In this case, the shear strength can be appropriately adjusted by the number of pins and the like.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings. The present invention is not limited by the embodiment.

(First Embodiment) FIG. 1 is a partial sectional view showing a cask according to a first embodiment of the present invention. In the cask 100, a step 3 is provided on the flange 2 of the trunk body 1, and the primary lid 4 is fitted on the upper surface of the step. A metal gasket 6 is arranged in the seal groove 5 of the primary lid 4, and the space between the primary lid 4 and the flange portion 2 is kept closed by crushing and plastically deforming the metal gasket 6. The secondary lid 7 is fitted into the top 8 of the flange portion 2, and a metal gasket 10 is provided in a seal groove 9 provided in the secondary lid 7, as described above.

The primary lid 4 and the flange 2 are connected to the bolt 11
(M48). Also, bolt hole 1
2 is formed into a tapered shape that is continuous from the primary lid 4 to the flange portion 2 in a counterbore 13 provided on the peripheral edge of the primary lid 4. An internal thread 14 is cut in the bolt hole 12 on the flange side. In addition, in order to ensure the accuracy of the tapered surface, it is preferable that the taper processing is performed by fitting the primary lid 4 and the flange portion 2 and performing machining at the same time. A stainless steel or carbon steel tapered sleeve 15 is fitted into the bolt hole 12. The bolt 11 penetrates through the inside of the cylinder of the tapered sleeve 15 and is screwed with the female screw 14 on the flange side at the screw portion 11a. The bolt 11 is also made of stainless steel or carbon steel, which is the same material as the body 1.

It is sufficient that the bolt 11 can penetrate the inside of the cylinder of the tapered sleeve 15, and there may be some clearance between the cylinder surface and the shaft surface of the bolt 11. The washer 16 of the bolt 11 is in contact with the end surface of the tapered sleeve 15, and the tapered sleeve 15 is pushed in by tightening the bolt 11. By this bolt fastening, the primary lid 4 is pressed against the flange 2,
The metal gasket 6 is plastically deformed by the action, and the inside of the cavity 17 is sealed. By fitting the tapered sleeve 15 into the bolt hole 12, the primary lid 4 can be prevented from moving in the radial direction when the cask 100 falls.

As described above, the bolt hole 20 on the secondary lid 7 side is also
The secondary lid 7 is processed into a tapered shape that continues from the flange 2 to the flange 2. The bolt 21 is passed through the inside of the cylinder, and is screwed with the screw 22 to be formed on the flange. Further, a taper sleeve 23 made of stainless steel or carbon steel is fitted into the bolt hole 20.
Also in this case, the taper sleeve 23 is pushed in by screwing the bolt 21, and the sealing by the metal gasket 10 is performed by pressing the secondary lid 7 against the flange portion 2. By fitting the tapered sleeve 23 into the bolt hole 20, the secondary lid 7
Can be prevented from moving in the radial direction.

FIG. 2 is a plan view showing locations where fixing is performed using a tapered sleeve. The tapered sleeve 15,
The structure for fixing the primary lid 4 and the secondary lid 7 by 23 is as follows.
It is not necessary to adopt it to all of the bolt fastening portions 25 and 26 provided on the periphery of the primary lid 4 and the secondary lid 7, and when the cask 100 falls, the shear load by the primary lid 4 and the secondary lid 7 is reduced. It is enough to be able to receive. Specifically, the peripheral edges of the primary lid 4 and the secondary lid 7
Eight bolt fastening portions 25 and 26 are provided, and the bolt fastening portions 25 and 26 may be employed equally at about six locations (indicated by reference numerals 25a and 26a in the drawing). In addition, the taper sleeve 1
Since the shear strengths 5 and 23 vary depending on the size of the cask 100, the weight of the lid, and the like, the number of employed portions and the nominal diameter of the tapered sleeves 15 and 23 are determined based on such conditions.

As described above, in the cask 100 according to the first embodiment, since the taper sleeves 15 and 23 prevent the primary cover 4 and the secondary cover 7 from moving in the radial direction, the lateral displacement of the metal gaskets 6 and 10 is prevented. can do. As a result, sealing during the transportation of the cask 100 is guaranteed. Further, there is no need to replace the metal gasket 10 with an O-ring when transporting the cask 100, and the transport can be performed as it is. As described above, since the work of replacing the O-ring requires a great deal of time, omitting the replacement work greatly contributes to simplifying the cask transportation work.

In the first embodiment, the tapered sleeves 15 and 23 are used for both the primary lid 4 and the secondary lid 7. However, if the purpose is only to omit the operation of replacing the O-ring. The taper sleeve 23 can be used only on the secondary lid 7 side. Although not shown, a parallel sleeve may be used instead of the tapered sleeves 15 and 23. In this case, the bolt holes may be ordinary holes. Further, the maximum clearance between the bolt hole and the sleeve is set to be equal to or less than the allowable shift amount of the metal gaskets 6, 10.

(Embodiment 2) FIG. 3 is a partial sectional view showing a cask according to Embodiment 2 of the present invention. FIG. 4 is an explanatory view showing the assembly of the parallel pins in the cask shown in FIG. This cask 200 is characterized in that parallel pins 31 and 32 are used to prevent the primary lid 4 and the secondary lid 7 from moving in the radial direction. The other configuration is the same as that of the above-mentioned conventional cask, and the description thereof is omitted.

In this cask 200, a continuous pin hole 33 is formed by machining from the primary lid 4 to the flange portion 2 of the body 1, and the parallel pin 31 is inserted into the pin hole 33 from above the primary lid 4. . The parallel pin 31 has a nominal diameter of about 40 mm and is provided between adjacent bolt fastening portions (not shown). A cover plate 34 for preventing the parallel pin 31 from coming off is provided above the pin hole 33 with bolts 3.
It is fixed at 5. Thereby, the primary lid 4 and the flange portion 2 are fixed, and the primary lid 4 can be prevented from moving in the radial direction. Here, the tolerance of the parallel pin 31 and the pin hole 33
Is preferably set such that the maximum clearance between them is not more than the allowable shift amount of the metal gasket 6. Specifically, the allowable shift amount of the metal gasket 6 is 0.2 m
m to 0.3 mm, the maximum clearance between the two may be set to about 0.3 mm. Note that this maximum clearance is not based on the nominal diameter of the parallel pin 31 but on the basis of the allowable shift amount of the metal gasket 6. Therefore, even if the nominal diameter of the parallel pin 31 is different, it should be set to be substantially the same. There is.

The parallel pin 31 and the pin hole 33 may be tightly fitted. In this case, only the amount of deformation of the parallel pin 31 due to the load on the primary lid 4 is sufficient, and the maximum interference may be set according to a general standard. By doing so, the movement of the primary lid 4 can be made extremely small. In addition, at the upper end of the parallel pin 31,
A screw hole 36 for pulling out, to which an eyebolt or the like can be attached, is provided. The number and arrangement of the parallel pins 31 need only be able to receive the shear load by the primary lid 4 as in the first embodiment, and are determined based on the size of the cask 200, the weight of the lid, and the like.

On the other hand, for fixing the secondary lid 7 and the flange 2 as well, the parallel pin 32 is inserted into the pin hole 37 and the lid plate 38 is fixed with a bolt 39 so as not to come off, as described above. Further, as shown in FIG. 4, the parallel pin 32
It is provided between adjacent bolt fastening portions 26, 26. This prevents the secondary lid 7 from moving in the radial direction. Also in the above-described cask 200, since the parallel pins 31 and 32 prevent the primary cover 4 and the secondary cover 7 from moving in the radial direction, the lateral displacement of the metal gaskets 6 and 10 can be prevented. There is no need to replace the metal gaskets 6, 10 with O-rings when transporting the 200, and it is possible to transport it as it is.

FIG. 5 is a sectional view showing a modification of the cask according to the second embodiment of the present invention.
50 shows a lid mounting structure of No. 50. Although the secondary lid 7 is taken as an example in FIG. 1, the primary lid 4 has the same configuration. This cask 250 has a tapered pin 41 provided between adjacent bolt fastening portions 26 provided on the peripheral edge of the secondary lid 7. The tapered hole 42 is machined with the secondary lid 7 fitted in the flange portion 2. A lid plate 43 for preventing the taper pin 41 from coming off is fixed to the upper part of the tapered hole 42 by a bolt 44. At the upper end of the tapered pin 41,
A pull-out screw hole 45 to which an eyebolt or the like can be attached is provided. Such a configuration also prevents the primary lid 4 and the secondary lid 7 from moving in the radial direction, and
Lateral displacement can be prevented. For this reason, the cask 250 can be transported without changing the metal gasket 10 by replacing the O-ring. The taper pin 41 used
The number and arrangement of
The size is determined based on the size of the lid and the weight of the lid.

(Embodiment 3) FIG. 6 is a sectional view showing a cask lid mounting structure according to Embodiment 3 of the present invention. Although the secondary lid 7 is taken as an example in FIG.
Has the same configuration. This cask 300 has a secondary lid 7
It is characterized in that the bolt 50 used for the attachment has a pin function. The pin hole 51 is formed continuously from the secondary lid 7 to the flange portion 2 of the trunk main body 1, and a female screw 52 is cut on the flange side leaving a pin hole portion. In the bolt 50, the diameter of the shaft 53 is larger than the diameter of the screw 54, and the shaft 53 functions as a pin. A bolt 50 is inserted into the pin hole 51, and its screw portion 54 is
2, the secondary lid 7 can be fixed to the flange 2. Further, since the shaft portion 53 of the bolt 50 is fitted over the secondary lid 7 and the flange portion 2, the movement of the secondary cover 7 when the cask falls is not affected by the shaft portion 53 of the bolt 50.
Blocked by As a result, lateral displacement of the metal gasket 10 is prevented.

The maximum clearance between the bolt shaft 53 and the pin hole 51 is set to be equal to or less than the allowable displacement of the metal gasket 10 as described above. Further, the number and arrangement of the bolts 50 need only be able to receive the shear load by the secondary lid 7 as in the first embodiment, and are determined based on the size of the cask 300, the weight of the lid, and the like. According to the above-described cask 300, since the lateral displacement of the metal gasket 10 during the cask transportation can be prevented, the work of replacing the metal gasket 10 with the O-ring can be omitted, and the bolts 50 having the pin function can be used to secure the primary lid 4 and the secondary lid 7 to each other. Since the movement in the radial direction can be prevented, the configuration becomes extremely simple.

[0039]

As described above, in the cask according to the present invention (claim 1), a continuous pin hole is provided from the peripheral edge of the lid to the end of the trunk body, and the pin is inserted into this pin hole. Thereby, the movement of the lid is prevented, and the lateral displacement of the metal gasket is prevented. Therefore, it is not necessary to replace the metal gasket with the O-ring during transportation.

In the cask according to the present invention (claim 2), a tapered hole is provided continuously from the peripheral edge of the lid to the end of the body, and a tapered pin is inserted into the tapered hole.
The movement of the lid is further prevented, and the lateral displacement of the metal gasket is effectively prevented. Therefore, it is not necessary to replace the metal gasket with the O-ring during transportation.

In the cask according to the present invention (claim 3), the bolt holes through which the bolts pass are formed in a tapered shape continuous from the peripheral edge of the lid to the end of the body, and the tapered bolt holes are tapered. Since the sleeve is inserted and the trunk body and the lid are bolted through the bolt in the cylinder of the tapered sleeve, the bolt holes are tapered, so that movement of the lid is prevented with a simple structure, The lateral displacement of the gasket can be prevented. Therefore, it is not necessary to replace the metal gasket with the O-ring during transportation.

Further, in the cask according to the present invention (claim 4), a continuous pin hole is provided from the peripheral edge of the lid to the end of the trunk body, and the pin hole is left in the pin hole on the trunk body side. Since the screw was cut, the shaft of the bolt was fitted into the pin hole, and the thread of the bolt was screwed into the female thread,
Both pin function and fastening function can be used. Therefore, movement of the lid can be prevented with a simple structure, and lateral displacement of the metal gasket can be prevented. Therefore, it is not necessary to replace the metal gasket with the O-ring during transportation.

Further, in the cask according to the present invention (claim 5), the maximum clearance between the shaft of the pin or bolt and the pin hole, the maximum clearance between the tapered hole and the tapered pin or the tapered sleeve, and the allowable displacement of the metal gasket. Since the amount is set to be equal to or less than the amount, the sealing can be maintained even when the cask falls.

Further, in the cask according to the present invention (claim 6), the fixed portion of the pin or bolt by the shaft portion and the pin hole, or the fixed portion by the tapered hole and the tapered pin or the tapered sleeve is replaced with the pin or bolt. The number to be used is determined based on the shear strength of the shaft portion or the tapered sleeve, and these are arranged substantially evenly around the lid to fix the lid and the body. For this reason, the shear strength can be appropriately adjusted by the number of pins and the like.

[Brief description of the drawings]

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

FIG. 2 is a plan view showing locations where fixing is performed using a tapered sleeve.

FIG. 3 is a partial sectional view showing a cask according to a second embodiment of the present invention.

FIG. 4 is an explanatory view showing assembling of parallel pins in the cask shown in FIG. 3;

FIG. 5 is a sectional view showing a modification of the cask according to the second embodiment of the present invention.

FIG. 6 is a sectional view showing a cask lid mounting structure according to a third embodiment of the present invention;

FIG. 7 is a sectional view showing the structure of a conventional cask.

FIG. 8 is a partially enlarged view of the cask shown in FIG. 7;

FIG. 9 is an enlarged view showing a seal portion of a cask.

[Explanation of symbols]

 Reference Signs List 100 Cask 1 Body 2 Flange 3 Step 4 Primary lid 5 Seal groove 6 Metal gasket 7 Secondary lid 9 Seal groove 10 Metal gasket 11, 21 Bolt 12, 20 Bolt hole 15, 23 Taper sleeve 25, 26 Bolt fastening part

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Katsunari Ozono 1-1-1, Wadazakicho, Hyogo-ku, Kobe-shi Inside the Kobe Shipyard, Sanishi Heavy Industries Co., Ltd. Kobe Shipyard, Sanishi Heavy Industries Co., Ltd. (72) Inventor Kouji Takeshita 15 Kita-zai, Kakogawa-cho, Kakogawa-shi, Hyogo Prefecture Kansai Giken Co., Ltd.

Claims (6)

[Claims] A cavity with a bottom is formed in a trunk body for shielding gamma rays, a basket for storing spent fuel assemblies is accommodated in the cavity, and a lid is attached to a cavity opening side of the trunk body. In a cask in which a metal gasket is interposed between an end of the trunk main body and a peripheral edge of the lid to maintain a seal in the cavity, a pin hole is provided continuously from the peripheral edge of the lid to an end of the trunk main body. A cask characterized by inserting a pin into the pin hole. 2. A bottomed cavity is formed in a trunk body for shielding gamma rays, a basket for storing a spent fuel assembly is accommodated in the cavity, and a lid is attached to the cavity opening side of the trunk body. In a cask in which a metal gasket is interposed between an end of the trunk main body and a peripheral edge of the lid to maintain sealing in the cavity, a tapered hole is provided continuously from the peripheral edge of the lid to an end of the trunk main body. A cask characterized in that a taper pin is inserted into the tapered hole. 3. A cavity with a bottom is formed in a trunk main body for shielding gamma rays, a basket for storing a spent fuel assembly is accommodated in the cavity, and a plurality of lids are provided on a peripheral edge of a lid provided on a cavity opening side. In a cask for providing a bolt hole, bolting the lid to the cavity opening side end with the bolt hole, and interposing a metal gasket between the end of the trunk body and the lid to maintain the seal in the cavity, The bolt hole through which the bolt passes is formed in a tapered shape continuous from the peripheral edge of the lid to the end of the trunk body, a tapered sleeve is inserted into the tapered bolt hole, and the bolt is passed through the cylinder of the tapered sleeve. A cask characterized in that a main body and a lid are bolted. 4. A cavity with a bottom is formed in a trunk body for shielding gamma rays, a basket for storing a spent fuel assembly is accommodated in the cavity, and a lid is attached to a cavity opening side of the trunk body. In a cask in which a metal gasket is interposed between an end of the trunk main body and a peripheral edge of the lid to maintain a seal in the cavity, a continuous pin hole is provided from the peripheral edge of the lid to an end of the trunk main body. A female screw is cut while leaving the pin hole in the pin hole on the trunk body side, a shaft portion of the bolt is fitted into the pin hole, and a screw portion of the bolt is screwed into the female screw. Cask. 5. The method according to claim 1, wherein a maximum clearance between the shaft of the pin or the bolt and the pin hole or a maximum clearance between the tapered hole and the tapered pin or the tapered sleeve is set to be equal to or less than an allowable shift amount of the metal gasket. The cask according to any one of claims 1 to 4, characterized in that: 6. The fixing part of the pin or bolt shaft and the pin hole, or the fixing part of the taper hole and the taper pin or taper sleeve, is used to reduce the shear strength of the pin or bolt shaft or the taper sleeve. The cask according to any one of claims 1 to 5, wherein the number to be used is determined on the basis of the number, and these are arranged substantially evenly around the lid to fix the lid and the trunk body.