JP7309638B2 - storage container - Google Patents

Description

TECHNICAL FIELD The present invention relates to a radioactive substance storage container in which radioactive substances are stored.

A radioactive substance is stored in a cylindrical container body with a bottom in water that can shield radiation. After closing the opening of the container body with the primary lid in water, the container body containing the radioactive material and the primary lid are taken out of the water. Thereafter, the primary lid is attached to the container body with bolts, water is removed from the container body, the inside of the container body is dried, and helium gas is filled. A secondary lid is attached to the container body and the space between the primary and secondary lids is vacuum dried.

In the above series of steps, the radioactive material is contained in the container body in water, and the opening of the container body is closed with the primary lid, so that water enters the bolt insertion holes formed in the primary lid and the container body. Water that has entered a bolt insertion hole or the like is difficult to remove and tends to remain at the bottom of the hole or the like. Residual water evaporates and condenses between the primary and secondary lids, and may corrode the container or metal gaskets. desirable.

In the storage container of Patent Document 1, a primary lid tightening bolt that attaches the primary lid to the container body is formed with a through hole penetrating in the axial direction. Water remaining at the bottom of the bolt insertion hole is discharged from the bolt insertion hole through the through hole of the primary lid tightening bolt.

JP 2002-2777585 A

When a through hole penetrating in the axial direction is formed in the primary lid tightening bolt as in Patent Document 1, the strength of the primary lid tightening bolt is reduced. Since the bolt tightening force required to tighten the primary lid is determined by the design requirements, if there is a through hole, the stress generated in the bolt will increase, and the tolerance for the design standard value of the stress of the bolt material will become smaller. Or, it is necessary to increase the diameter of the bolt.

SUMMARY OF THE INVENTION An object of the present invention is to provide a radioactive substance storage container capable of discharging water remaining in bolt insertion holes to the outside without reducing the strength of the primary lid tightening bolts.

A radioactive substance storage container of the present invention comprises a bottomed cylindrical body portion having a storage space for storing a radioactive substance, a primary lid disposed at one end of the body portion, and a primary lid disposed outside the primary lid. a secondary lid, a bolt for attaching the primary lid to one end of the barrel, and a washer disposed between the head of the bolt and the primary lid, the washer having a thickness direction of A radially penetrating hole is formed in the middle of the .

According to the present invention, water or the like remaining in the bolt insertion hole can be discharged to the outside without reducing the strength of the primary lid tightening bolt.

1 is a cross-sectional view of a radioactive substance storage container according to a first embodiment of the present invention; FIG. FIG. 2 is an enlarged sectional view of II of the radioactive substance storage container shown in FIG. 1; It is a top view of a washer. FIG. 3B is a cross-sectional view of the washer (a cross-sectional view taken along line IIIB-IIIB in FIG. 3A); FIG. 7 is an enlarged cross-sectional view of the vicinity of the bolt of the radioactive substance storage container according to the second embodiment of the present invention; FIG. 11 is a cross-sectional view of a washer of a radioactive substance storage container according to a modification;

[First Embodiment]
As shown in FIG. 1 , the radioactive substance storage container 1 has a bottomed cylindrical body 2 , and a primary lid 3 and a secondary lid 4 arranged at one end of the body 2 . In FIG. 1, hatching indicating a cross section is omitted. A radioactive substance is stored in the radioactive substance storage container 1 . Radioactive material is, for example, spent fuel or radioactive waste. Radioactive waste includes metal waste and plastic waste.

A space 2S is formed in the body 2 to accommodate the radioactive material. The trunk portion 2 is made of metal. Shielding layers 11 and 12 for shielding radiation are arranged outside the body 2 .

The primary lid 3 is attached to one end of the body 2 with bolts 5 . The primary lid 3 is made of metal. A secondary lid 4 is attached to one end of the body 2 with a bolt 6 . A secondary lid 4 is arranged outside the primary lid 3 . The outside of the primary lid 3 is the side opposite to the space 2S with respect to the primary lid 3 .

FIG. 2 shows the periphery of the bolt 5 in FIG. FIG. 2 is an enlarged view of II in FIG. As shown in FIG. 2 , the shaft portion 21 of the bolt 5 is arranged in the bolt insertion hole 30 . The bolt insertion hole 30 is a hole communicating with the primary lid 3 and the body portion 2 .

A head 22 of the bolt 5 is arranged in the space M between the primary lid 3 and the secondary lid 4 . A washer 7 is arranged between the head 22 of the bolt 5 and the primary lid 3 .

The washer 7 is annular, as shown in FIG. 3A. As shown in FIG. 3B, the washer 7 is formed with a first hole 7a and a second hole 7b penetrating in the radial direction. The first hole 7a and the second hole 7b are formed in the middle of the washer 7 in the thickness direction. The “thickness direction of the washer 7” is a direction orthogonal to the radial direction of the washer 7, and includes one end face (upper end face in FIG. 3B) 7x and the other end face (upper end face in FIG. 3B) 7x in the thickness direction lower end surface) 7y. “Midway in the thickness direction of the washer 7 ” is between one end face 7 x and the other end face 7 y of the washer 7 in the thickness direction of the washer 7 . "Between the one end face 7x and the other end face 7y of the washer 7" does not include the one end face 7x and the other end face 7y of the washer 7.

The first hole 7a and the second hole 7b are formed near the center Ct of the washer 7 in the thickness direction. The first hole 7 a and the second hole 7 b are formed at the same position in the thickness direction of the washer 7 , but may be formed at different positions in the thickness direction of the washer 7 .

As shown in FIG. 3A, the first hole 7a and the second hole 7b face each other in the radial direction. The first hole 7a and the second hole 7b are separated from each other by a half circumference in the circumferential direction of the washer 7 . The first hole 7a is formed at a position obtained by rotating the second hole 7b by 180 degrees about the center C of the annular washer 7. As shown in FIG.

In the present invention, "a plurality of holes formed midway in the thickness direction of the washer and penetrating in the radial direction are spaced apart in the circumferential direction of the washer" means that the plurality of holes are spaced apart in the circumferential direction of the washer, regardless of whether they are formed in the same position with respect to In the present invention, "a plurality of holes formed midway in the thickness direction of the washer and penetrating in the radial direction are spaced apart in the circumferential direction of the washer" means It may mean that a plurality of holes are separated in the circumferential direction of the washer, or it may mean that a plurality of holes formed at different positions in the thickness direction of the washer are separated in the circumferential direction of the washer. be.

As shown in FIG. 3B, the inner peripheral surface of the washer 7 is formed with a first chamfered portion 7h and a second chamfered portion 7i. The first chamfered portion 7h is a portion that is chamfered such that the inner diameter decreases from one end (upper end in FIG. 3B) 7u in the thickness direction toward the center Ct in the thickness direction. The second chamfered portion 7i is a portion chamfered so that the inner diameter decreases from the other end (lower end in FIG. 3B) 7l in the thickness direction toward the center Ct in the thickness direction.

A radioactive substance is stored in the radioactive substance storage container 1 (see FIG. 1) by the following method.
Under water, the radioactive material is stored in the body 2, and the opening of the body 2 is closed with the primary lid 3. The body 2 containing the radioactive material and the primary lid 3 are taken out of the water, and the primary lid 3 is attached to the body 2 with bolts 5 . The water inside the barrel 2 is drained, the inside of the barrel 2 is dried, and helium gas is filled. A secondary lid 4 is arranged outside the primary lid 3, and the secondary lid 4 is attached to the body portion 2 with bolts 6. - 特許庁A space M surrounded by the primary lid 3, the secondary lid 4, and the body portion 2 is vacuum-dried (see FIG. 2).

When the space M is vacuum-dried, as shown in the enlarged view of FIG. It is discharged from hole 30 .

As described above, water or the like remaining in the bolt insertion hole 30 can be efficiently discharged from the bolt insertion hole 30 . In the present embodiment, since water or the like remaining in the bolt insertion hole 30 can be discharged without forming a hole penetrating the bolt 5 in the axial direction, the strength of the bolt 5 is not lowered.
As described above, water or the like remaining in the bolt insertion hole 30 can be discharged to the outside from the bolt insertion hole 30 without reducing the strength of the bolt 5 .

Also, when the primary lid 3 is attached to the body 2 (see FIGS. 1 and 2), tightening the bolt 5 may deform the end surface of the washer 7 (one end surface 7x shown in FIG. 3B). However, as shown in FIG. 3B, the first hole 7a and the second hole 7b of the washer 7 are formed midway in the thickness direction, in other words, between one end face 7x and the other end face 7y of the washer 7. Therefore, even if the end face (one end face 7x) of the bolt 5 is deformed, the first hole 7a and the second hole 7b are not blocked. Therefore, a passage for water or the like is secured.

Further, as shown in FIG. 3B, since a plurality of holes (the first hole 7a and the second hole 7b) are formed in the washer 7, even if one of the holes is blocked by water or the like, the other holes Water or the like in the bolt insertion hole 30 can be discharged from the hole.

Further, as shown in FIG. 3B, one end portion (the upper end portion in FIG. 3B) of the inner peripheral surface of the washer 7 is chamfered to form a first chamfered portion 7h. A second chamfered portion 7i is formed by chamfering the other end portion (lower end portion in FIG. 3B) of the inner peripheral surface of the washer 7 .
As shown in the enlarged view of FIG. 2, the first chamfered portion 7h is arranged along the head portion 22 of the bolt 5 and the corner portion 5k of the shaft portion 21. As shown in FIG. Although the corner 5k is rounded, the first chamfered portion 7h can be arranged along the rounded corner 5k. As a result, the washer 7 is less likely to deform when the bolt 5 is tightened.
Further, even when the washer 7 is attached to one side in the radial direction, the washer 7 does not hang on the bolt hole of the primary lid 3, and the washer 7 and the primary lid 3 are brought into contact with each other.
Furthermore, since chamfered portions (first chamfered portion 7h, second chamfered portion 7i) are formed at both ends in the thickness direction of the inner peripheral surface of the washer 7, even if the front and back of the washer 7 are reversed, The effects described above are obtained. Therefore, when attaching the primary lid 3 to the body 2 with the bolts 5, it is not necessary to consider the front and back of the washer 7.

[Second embodiment]
Next, a second embodiment of the invention will be described with reference to FIG. The second embodiment differs from the first embodiment in that powdery particles adhere to the shaft portion 21 of the bolt 5 . In addition, the same code|symbol is used about the structure same as 1st Embodiment mentioned above, and the description is abbreviate|omitted suitably.

As shown in the enlarged view of FIG. 4 , powdery particles 110 are present around the shaft portion 21 of the bolt 5 in the bolt insertion hole 30 . The powdery particles 110 reliably form a gap G around the shaft portion 21 of the bolt 5 in the bolt insertion hole 30 . Powdered particles are solid. Powdery particles are powders. The powdery particles do not include lumps and larger particles (granules, etc.) formed by hardening the powder. The powdery particles are preferably particles that do not corrode metal. The powdery particles are, for example, graphite powder, molybdenum disulfide, but are not limited to these.

Water or the like remaining in the bolt insertion hole 30 is sucked up into the gap G by vacuum drying, as shown in the enlarged view of FIG. The sucked water is discharged through the first hole 7a and the second hole 7b of the washer 7.

As described above, according to the radioactive substance storage container of the second embodiment, like the radioactive substance storage container 1 of the first embodiment, water remaining in the bolt insertion hole 30 can be removed without reducing the strength of the bolt 5 . can be discharged to the outside. In addition, since water or the like remaining in the bolt insertion hole 30 is sucked up into the gap S by vacuum drying, the water or the like is easily discharged from the bolt insertion hole 30 .

Although the embodiments of the present invention have been described above with reference to the drawings, it should be considered that the specific configuration is not limited to these embodiments. The scope of the present invention is indicated by the scope of the claims rather than the above description, and includes all modifications within the scope and meaning equivalent to the scope of the claims.

For example, in the above-described first and second embodiments, as shown in FIGS. 3A and 3B, the washer 7 has two holes (first holes 7a, A second hole 7b) is formed. However, the washer may have only one hole or three or more holes extending radially through the washer in the middle of the thickness direction. The number of holes is not limited, but preferably two.

In the first embodiment and the second embodiment, as shown in FIG. 3A, two holes (first hole 7a and second hole 7b) radially penetrate through the washer 7 in the middle of its thickness direction. , are separated by half a circumference in the circumferential direction of the washer 7 . However, the interval between the holes does not have to be half the circumference of the washer 7 in the circumferential direction.

In the first and second embodiments, the first hole 7a and the second hole 7b are formed near the center Ct in the thickness direction of the washer 7, as shown in FIG. 3B. However, the first hole 7a and the second hole 7b may not be formed near the center Ct of the washer 7 in the thickness direction. The hole penetrating in the radial direction of the washer may be formed at any position in the middle of the thickness direction.

In the first and second embodiments described above, as shown in FIG. 3B, the inner peripheral surface of the washer 7 is provided with a first chamfered portion 7h at one end in the thickness direction. A second chamfered portion 7i is formed at the other end of the . In other words, both ends in the thickness direction of the inner peripheral surface of the washer 7 are chamfered. However, the inner peripheral surface of the washer 7 may not be chamfered. Further, as shown in FIG. 5, a chamfered portion 207i may be formed only at one end in the thickness direction on the inner peripheral surface of the washer 207. As shown in FIG.

Reference Signs List 1, 301 radioactive substance storage container 2 trunk 2S space 3 primary lid 4, 304 secondary lid 5, 6 bolt 7 washer 7a first hole 7b second hole 7h first chamfered portion 7i second chamfered portion 7x one end face 7y Other end face 8A, 208A Peripheral side face 8B, 208B One end face 8C, 208C Other end face 21 Shaft 22 Head 30 Bolt insertion hole 110 Particle 310 Outer container 311 Main body of container S Gap

Claims (4)

a bottomed tubular body having a storage space in which the radioactive material is stored;
a primary lid disposed at one end of the body;
a secondary lid disposed outside the primary lid;
a bolt that attaches the primary lid to one end of the barrel;
a washer disposed between the head of the bolt and the primary lid,
A container according to claim 1, wherein the washer has a radially penetrating hole in the middle of the thickness direction. 2. The storage container according to claim 1, wherein powdery particles are present around the shank of the bolt. A plurality of said holes are formed in said washer,
3. The storage container according to claim 1, wherein the plurality of holes are spaced apart in the circumferential direction of the washer. 4. The washer according to any one of claims 1 to 3, wherein the inner peripheral surface of the washer is chamfered so that the inner diameter decreases as it approaches the center in the thickness direction from one end in the thickness direction. storage container.

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