Leak prevention device and installation structure of the leak prevention device

Abstract

To install a leakage prevention device before a wall material is installed.SOLUTION: A leakage preventing device 10 prevents radiation leakage from an open hole 11h in a ceiling wall 11 by covering the open hole 11h from a rear side of the ceiling wall 11. The leakage preventing device 10 includes: a main body part 20 which is formed into a box shape with a closed bottom including a cylindrical peripheral wall 21 having an opening 25 sized to surround the open hole 11h at a tip 21a, and a bottom wall 22 facing the opening 25 and formed of a material preventing radiation leakage; and a fitting part 50 located on closer to the bottom wall 22 side than the tip 21a of the peripheral wall 21 and attached to a second long member 13b in which the ceiling wall 11 is fixed. The fitting part 50 can be attached to the second long material 13b with the tip 21a of the peripheral wall 21 in contact with a back side surface 11b.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a leak prevention device and an installation structure for the leak prevention device. [Background technology]

[0002] Leak prevention devices are used to prevent radiation from leaking from the inside to the outside of a room such as an X-ray room. For example, the leak prevention device described in Patent Document 1 prevents radiation from leaking from a through-hole formed in a wall material by covering the through-hole from the back side of the wall material. The leak prevention device has a box-shaped box with a bottom and a flange located at the open end of the box. The flange is fixed to the back surface of the wall material, so that the leak prevention device is installed on the back side of the wall material. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-50860 Summary of the Invention [Problem to be solved by the invention]

[0004] The leak prevention device described in Patent Document 1 is installed by fixing the flange to the wall material, so it can only be installed after the wall material has been installed. There has been a demand for an improvement to the leak prevention device so that it can be installed before the wall material is installed. [Means for solving the problem]

[0005] Various aspects of a leakage prevention device and an installation structure for the leakage prevention device for solving the above problems will be described. [Embodiment 1] A leakage prevention device that covers a through hole formed in a wall material from the back side of the wall material to prevent radiation from leaking from the through hole, the leakage prevention device having a bottomed box shape with a cylindrical peripheral wall that forms an opening at its tip that is large enough to surround the through hole, and a bottom wall that faces the opening, and is equipped with a main body formed from a material that prevents radiation from leaking, and an attachment part that is located closer to the bottom wall than the tip of the peripheral wall and is attached to a fixing member to which the wall material is fixed, and the attachment part can be attached to the fixing member with the tip of the peripheral wall abutting against the back side of the wall material.

[0006] [Aspect 2] The main body portion is formed from a material that prevents leakage of the radiation, and has a bottomed, box-shaped shielding portion with a cylindrical shielding peripheral wall and a shielding bottom wall, and a cylindrical overlapping portion that is formed from a material that is more rigid than the shielding portion and overlaps the shielding peripheral wall, the peripheral wall includes the shielding peripheral wall and the overlapping portion, the bottom wall includes the shielding bottom wall, the opening is formed at the tip of the shielding peripheral wall, and at least the portion of the overlapping portion that faces the shielding portion is located closer to the bottom wall than the tip of the shielding peripheral wall. This is a leakage prevention device described in [Aspect 1].

[0007] [Embodiment 3] A leakage prevention device according to [Embodiment 2], in which a notch is provided in advance in the shielding peripheral wall from the tip of the shielding peripheral wall toward the bottom wall. [Aspect 4] A leakage prevention device described in any one of [Aspect 1] to [Aspect 3], wherein the mounting portion is separate from the main body portion and has an attachment portion that is attached to the main body portion, and the attachment portion can be attached to the main body portion by changing the position of the mounting portion relative to the opening to a different position that is shifted in the opposing direction between the opening and the bottom wall.

[0008] [Aspect 5] [Aspect 4] An installation structure for a leak prevention device for installing the leak prevention device described in [Aspect 4], wherein the fixing member is the second long-length member of a ceiling underlayment material composed of a first long-length member and a second long-length member that overlaps the first long-length member in the vertical direction and intersects the first long-length member horizontally and is positioned below the first long-length member, the wall material consists of a ceiling wall fixed to the second long-length member, the main body portion is arranged with the opening facing downward, and the attachment portion can be attached to the main body portion by changing the installation position of the mounting portion relative to the opening to at least two positions offset in the vertical direction so that the mounting portion can be placed on the upper surface of each of the first long-length member and the second long-length member.

[0009] [Aspect 6] The main body portion is formed from a material that prevents leakage of the radiation, and has a bottomed, box-shaped shielding portion with a cylindrical shielding peripheral wall and a shielding bottom wall, and a cylindrical overlapping portion that is formed from a material that is more rigid than the shielding portion and overlaps the shielding peripheral wall, the peripheral wall includes the shielding peripheral wall and the overlapping portion, the bottom wall includes the shielding bottom wall, the opening is formed at the tip of the shielding peripheral wall, and the overlapping portion is entirely located at a position higher than the height of the upper surface of the fixing member and is located closer to the bottom wall than the tip of the shielding peripheral wall. This is an installation structure for a leakage prevention device described in [Aspect 5].

[0010] [Aspect 7] An installation structure for a leakage prevention device described in [Aspect 6], in which a notch is pre-formed in the shielding peripheral wall, the notch extending from the tip of the shielding peripheral wall toward the bottom wall, and the length of the notch is greater than the vertical height of the second elongated member. [Effects of the Invention]

[0011] According to this invention, the leak prevention device can be installed even before the wall material is installed. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 2 is a perspective view showing a ceiling wall, a foundation ceiling, and a leak prevention device according to an embodiment. [Figure 2] FIG. 2 is a top view showing the ceiling wall and the leak prevention device. [Figure 3] FIG. 2 is an exploded perspective view showing the leakage prevention device. [Figure 4] FIG. [Figure 5] FIG. 2 is a cross-sectional view showing the ceiling wall and the leak prevention device. [Figure 6] FIG. 3 is an enlarged cross-sectional view showing a portion of the ceiling wall and the leakage prevention device. [Figure 7] FIG. 3 is an enlarged cross-sectional view showing a portion of the ceiling wall and the leakage prevention device. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, an embodiment of a leakage prevention device and an installation structure for the leakage prevention device will be described with reference to the drawings. <Location of leak prevention equipment> As shown in FIG. 1 , the leakage prevention device 10 is located behind the ceiling wall 11. The ceiling wall 11 in this embodiment corresponds to a wall material. That is, the wall material in this embodiment is made of the ceiling wall 11. The ceiling wall 11 is installed at a distance from a foundation ceiling 12. The ceiling wall 11 and the foundation ceiling 12 form a double ceiling. The ceiling wall 11 may be made of a leakage prevention material that prevents radiation leakage. The ceiling wall 11 is used, for example, as the ceiling of a room such as an X-ray room. The leakage prevention material that constitutes the ceiling wall 11 can be, for example, a material that can shield X-rays and gamma rays, such as lead or iron, a material that can shield neutrons, such as polyethylene or boron-containing polyethylene, or a combination of these materials.

[0014] In this embodiment, the up-down direction is referred to as the up-down direction X, and directions that are perpendicular to the up-down direction X and perpendicular to each other are referred to as the first direction Y and the second direction Z. The up-down direction X is also the direction of gravity. The first direction Y and the second direction Z correspond to the horizontal direction. The front of the ceiling wall 11 means the bottom of the ceiling wall 11. The back of the ceiling wall 11 means the top of the ceiling wall 11.

[0015] The ceiling wall 11 has a flat plate shape. The ceiling wall 11 has a front side surface 11a located on the lower side in the vertical direction X and a back side surface 11b located on the upper side in the vertical direction X. The front side surface 11a and the back side surface 11b extend perpendicular to the vertical direction X.

[0016] A through hole 11h is formed in the ceiling wall 11 serving as a wall material. The through hole 11h penetrates between the front side surface 11a and the back side surface 11b. In this embodiment, the through hole 11h has a rectangular shape when viewed from the up-down direction X. The leakage prevention device 10 covers the through hole 11h formed in the ceiling wall 11 serving as a wall material from the back side of the ceiling wall 11, thereby preventing radiation from leaking through the through hole 11h.

[0017] The drawings illustrate a case where the number of leakage prevention devices 10 located on the back side of the ceiling wall 11 and the number of through holes 11h formed in the ceiling wall 11 are one each. The number of leakage prevention devices 10 located on the back side of the ceiling wall 11 and the number of through holes 11h formed in the ceiling wall 11 may be plural. Some or all of the plural through holes 11h formed in the ceiling wall 11 may be covered by leakage prevention devices 10. Multiple through holes 11h may be collectively covered by one leakage prevention device 10. A fixture (not shown) is fixed to the ceiling wall 11. The fixture is, for example, a lighting fixture such as a downlight. The downlight is attached inside the through hole 11h.

[0018] As shown in Figures 1 and 2, a ceiling base material 13 is provided between the ceiling wall 11 and the foundation ceiling 12. The ceiling base material 13 is composed of a first long material 13a and a second long material 13b. A plurality of first long materials 13a and a plurality of second long materials 13b are provided between the ceiling wall 11 and the foundation ceiling 12. The plurality of first long materials 13a are positioned apart from each other in the second direction Z. The plurality of second long materials 13b are positioned apart from each other in the first direction Y. The second long material 13b overlaps the first long material 13a in the up-down direction X. The second long material 13b is positioned below the first long material 13a.

[0019] The first elongated member 13a has an elongated shape extending upward from the ceiling wall 11 at a distance. The longitudinal direction of the first elongated member 13a extends in the first direction Y. The first elongated member 13a is connected to the foundation ceiling 12 by a hanging bolt 14. The second elongated member 13b has an elongated shape extending along the back surface 11b of the ceiling wall 11 serving as a wall material. The longitudinal direction of the second elongated member 13b extends in the second direction Z. As a result, the second elongated member 13b horizontally intersects with the first elongated member 13a. The second elongated member 13b is located between the first elongated member 13a and the ceiling wall 11 in the up-down direction X. The second elongated member 13b is connected to the first elongated member 13a and the ceiling wall 11.

[0020] The second long member 13b fixes the ceiling wall 11 from the back side of the ceiling wall 11. That is, in this embodiment, the second long member 13b of the ceiling base material 13 corresponds to a fixing member. The ceiling wall 11, which serves as a wall material, is fixed to the second long member 13b. The ceiling wall 11 is supported on the foundation ceiling 12 by the first long member 13a and the second long member 13b.

[0021] <Basic configuration of leak prevention equipment> As shown in FIG. 1 , the leakage prevention device 10 includes a main body 20 and an attachment portion 50. The main body 20 is shaped like a bottomed box, including a rectangular cylindrical peripheral wall 21 and a bottom wall 22. The axis of the peripheral wall 21 extends in the vertical direction X. The lower end of the peripheral wall 21 in the vertical direction X is referred to as the leading end 21a, and the upper end is referred to as the base end 21b. The peripheral wall 21 has an opening 25 at the leading end 21a. The opening 25 is rectangular when viewed in the vertical direction X. The opening 25 is sized to surround the through-hole 11h in the ceiling wall 11. Specifically, the opening 25 is slightly larger than the through-hole 11h. When a single leakage prevention device 10 covers multiple through-holes 11h, the opening 25 of the leakage prevention device 10 may be sized to surround the multiple through-holes 11h. The main body 20 is provided so that the opening 25 faces downward. The tip 21a of the peripheral wall 21 abuts against the back surface 11b of the ceiling wall 11.

[0022] The bottom wall 22 has a rectangular flat plate shape extending perpendicular to the up-down direction X. The bottom wall 22 is provided at the base end 21b of the peripheral wall 21, thereby closing the opening at the base end 21b of the peripheral wall 21. The bottom wall 22 faces the opening 25.

[0023] An accommodation space is formed inside the main body 20 to accommodate the fixture received through the opening 25. This accommodation space allows the main body 20 to accommodate a portion of a fixture, such as a downlight, that is installed in the through hole 11h and that is located on the back side of the ceiling wall 11. Note that, for example, if the entire fixture installed in the through hole 11h is located on the front side of the ceiling wall 11, the main body 20 does not need to have a large accommodation space as in the embodiment.

[0024] As shown in FIG. 3, the main body 20 has a bottomed box-shaped shielding portion 30 and a cylindrical overlapping portion 40. The shielding portion 30 is formed from a leakage prevention material that prevents radiation leakage. As a result, the main body 20 is formed to include a material that prevents radiation leakage. Note that examples of the leakage prevention material that can be used include materials that can block X-rays and gamma rays, such as lead and iron, materials that can block neutrons, such as polyethylene and boron-containing polyethylene, and combinations of these materials. The shielding portion 30 in this embodiment is made of lead.

[0025] <Shielding part> The shielding portion 30 is shaped like a bottomed box and includes a rectangular cylindrical shielding peripheral wall 31 and a shielding bottom wall 32. The axis of the shielding peripheral wall 31 extends in the up-down direction X. The shielding peripheral wall 31 has a pair of first shielding peripheral wall portions 33 and a pair of second shielding peripheral wall portions 34. The pair of first shielding peripheral wall portions 33 face each other in the first direction Y and are rectangular flat plate-shaped extending perpendicular to the first direction Y. The pair of second shielding peripheral wall portions 34 face each other in the second direction Z and are rectangular flat plate-shaped extending perpendicular to the second direction Z.

[0026] The lower end of the shielding peripheral wall 31 in the up-down direction X is also referred to as the tip 31a, and the upper end is also referred to as the base end 31b. The shielding peripheral wall 31 forms a shielding opening 35 at the tip 31a. The shielding opening 35 faces the shielding bottom wall 32. The shielding opening 35 functions as the opening 25 of the main body 20. The tip 31a of the shielding peripheral wall 31 functions as the tip 21a of the main body 20. That is, the opening 25 of the main body 20 is formed at the tip 31a of the shielding peripheral wall 31. The base end 31b of the shielding peripheral wall 31 functions as the base end 21b of the main body 20. The opening 25 is defined and formed at the lower end of the shielding peripheral wall 31 by a pair of first shielding peripheral wall portions 33 and a pair of second shielding peripheral wall portions 34. The tip 31 a of the peripheral shielding wall 31 is positioned so as to surround the through-hole 11 h of the ceiling wall 11 and is in contact with the rear surface 11 b of the ceiling wall 11 .

[0027] The shielding bottom wall 32 has a rectangular flat plate shape extending perpendicular to the up-down direction X. The shielding bottom wall 32 is provided at the base end 31b of the shielding peripheral wall 31, thereby closing the opening at the base end 31b of the shielding peripheral wall 31.

[0028] As shown in FIGS. 1 and 3 , a notch 36 is pre-formed in the shielding peripheral wall 31. The notch 36 extends from the tip 31a of the shielding peripheral wall 31 toward the bottom wall 22. The notch 36 is linear and extends in the vertical direction X. The dimension of the notch 36 in the vertical direction X is set to be equal to or greater than the height from the rear surface 11b of the ceiling wall 11 to the upper surface 13c of the second elongated member 13b serving as a fixing member. Therefore, the notch 36 has a length equal to or greater than the height of the second elongated member 13b in the vertical direction X, and extends from the tip 31a of the shielding peripheral wall 31 toward the bottom wall 22. The notches 36 formed in each pair of second shielding peripheral wall portions 34 may be one or more. In this embodiment, two notches 36 are formed in each pair of second shielding peripheral wall portions 34.

[0029] 3 and 4, bolt holes 31h are formed in the peripheral shielding wall 31. The bolt holes 31h are through-holes that penetrate the peripheral shielding wall 31. Two bolt holes 31h are formed in each of the pair of first peripheral shielding wall portions 33. A bolt B is inserted into each bolt hole 31h from the outside of the peripheral shielding wall 31. A nut N is attached to the tip of this bolt B from the inside of the peripheral shielding wall 31.

[0030] 3, introduction holes 30h are formed in the shielding peripheral wall 31 and the shielding bottom wall 32. The introduction holes 30h formed in the shielding peripheral wall 31 are through-holes that penetrate the shielding peripheral wall 31. The introduction holes 30h formed in the shielding bottom wall 32 are through-holes that penetrate the shielding bottom wall 32. In this embodiment, the introduction holes 30h are circular holes that are larger than the bolt holes 31h. The introduction holes 30h are formed in four locations in the shielding bottom wall 32: two locations in each of the pair of first shielding peripheral wall portions 33, two locations in each of the pair of second shielding peripheral wall portions 34, and four locations in the shielding bottom wall 32.

[0031] Each introduction hole 30h is blocked by a removable blocking member 30j. The blocking member 30j is located inside the introduction hole 30h and is a round, flat plate that is slightly smaller than the introduction hole 30h. The outer periphery of the blocking member 30j and the portion of the shielding unit 30 that is located around the introduction hole 30h are connected at multiple locations that are spaced apart in the circumferential direction of the introduction hole 30h. Therefore, the blocking member 30j can be easily removed from the introduction hole 30h by, for example, displacing the blocking member 30j. Removing the blocking member 30j from the introduction hole 30h connects the inside and outside of the shielding unit 30 through the introduction hole 30h, allowing a cable to be introduced into the introduction hole 30h. For example, the blocking member 30j is removed only from the introduction hole 30h that requires cable introduction, and the blocking member 30j is not removed from the other introduction holes 30h.

[0032] As shown in Figures 1 and 3, an insertion hole 32h is formed in the shielding bottom wall 32. The insertion hole 32h is a through-hole that penetrates the shielding bottom wall 32. In this embodiment, the insertion hole 32h is a circular hole that is smaller than the introduction hole 30h. The insertion hole 32h is formed, for example, in the center of the shielding bottom wall 32. For example, a suspension bolt 14 connected to the foundation ceiling 12 may be inserted into the insertion hole 32h. The main body 20 may be supported on the foundation ceiling 12 by the suspension bolt 14 inserted into the insertion hole 32h.

[0033] Before use, the insertion hole 32h is closed with a removable closing member. When the insertion hole 32h is used, this closing member is removed from the insertion hole 32h, thereby establishing communication between the inside and outside of the shielding part 30 via the insertion hole 32h. The closing member 30j that closes the introduction hole 30h and the closing member that closes the insertion hole 32h are made of the same material as the shielding peripheral wall 31 and the shielding bottom wall 32, and are therefore made of a material that prevents radiation leakage.

[0034] <Polymerization section> As shown in FIG. 3 , the overlapping portion 40 is formed of a material having higher rigidity than the shielding portion 30. The shielding portion 30 in this embodiment is made of resin. The overlapping portion 40 is shaped like a bottomed box, including a rectangular cylindrical overlapping peripheral wall 41 and an overlapping bottom wall 42. The axis of the overlapping peripheral wall 41 extends in the up-down direction X and coincides with the axis of the shielding peripheral wall 31. The overlapping peripheral wall 41 has a pair of first overlapping peripheral wall portions 43 and a pair of second overlapping peripheral wall portions 44. The pair of first overlapping peripheral wall portions 43 are rectangular flat plate-shaped portions that face each other in the first direction Y and extend perpendicular to the first direction Y. The pair of second overlapping peripheral wall portions 44 are rectangular flat plate-shaped portions that face each other in the second direction Z and extend perpendicular to the second direction Z.

[0035] The lower end of the overlapping peripheral wall 41 in the up-down direction X is also referred to as the tip 41a, and the upper end is also referred to as the base end 41b. The overlapping bottom wall 42 is a rectangular flat plate extending perpendicular to the up-down direction X. The overlapping bottom wall 42 is provided at the base end 41b of the overlapping peripheral wall 41, thereby closing the opening at the base end 41b of the overlapping peripheral wall 41. An overlapping opening 45 is formed at the tip 41a of the overlapping peripheral wall 41. The overlapping opening 45 faces the overlapping bottom wall 42.

[0036] As shown in Fig. 4, the overlapping portion 40 is located inside the shielding portion 30. The pair of first overlapping peripheral wall portions 43 is located between the pair of first shielding peripheral wall portions 33 in the first direction Y. The pair of second overlapping peripheral wall portions 44 is located between the pair of second shielding peripheral wall portions 34 in the second direction Z. The overlapping bottom wall 42 is located below the shielding bottom wall 32.

[0037] The overlapping peripheral wall 41 overlaps the shielding peripheral wall 31. In other words, the overlapping portion 40 overlaps the shielding peripheral wall 31. The outer surfaces of the pair of first overlapping peripheral wall portions 43 contact the inner surfaces of the pair of first shielding peripheral wall portions 33. The outer surfaces of the pair of second overlapping peripheral wall portions 44 contact the inner surfaces of the pair of second shielding peripheral wall portions 34. The overlapping bottom wall 42 overlaps the shielding bottom wall 32. The upper surface of the overlapping bottom wall 42 contacts the lower surface of the shielding bottom wall 32. The overlapping portions 40 and the shielding portion 30 may be bonded together at their contacting surfaces with double-sided tape or the like.

[0038] The tip 41a of the overlapping peripheral wall 41 is located higher than the tip 31a of the shielding peripheral wall 31. Therefore, the portion of the overlapping portion 40 that faces the shielding portion 30 is located closer to the bottom wall 22 than the tip 31a of the shielding peripheral wall 31. In this embodiment, the entire overlapping peripheral wall 41 and the entire overlapping bottom wall 42 face the shielding portion 30. In other words, the entire overlapping portion 40 is the portion of the overlapping portion 40 that faces the shielding portion 30.

[0039] 5, the entire overlapping portion 40 is located higher than the height of the upper surface 13c of the second elongated member 13b serving as the fixing member, and is located closer to the bottom wall 22 than the tip 31a of the peripheral shielding wall 31. The overlapping portion 40 is integrated with the shielding portion 30 with the overlapping opening 45 facing the tip 31a of the peripheral shielding wall 31. The overlapping portion 40 is integrated with the shielding portion 30 with the peripheral shielding wall 41 overlapping with the peripheral shielding wall 31 and the overlapping bottom wall 42 overlapping with the bottom shielding wall 32.

[0040] The overlapping peripheral wall 41, together with the shielding peripheral wall 31, constitutes the peripheral wall 21 of the main body portion 20. Therefore, the peripheral wall 21 includes the shielding peripheral wall 31 and the overlapping peripheral wall 41. The overlapping bottom wall 42, together with the shielding bottom wall 32, constitutes the bottom wall 22 of the main body portion 20. Therefore, the bottom wall 22 includes the shielding bottom wall 32 and the overlapping bottom wall 42.

[0041] As shown in Figures 3 and 4, bolt holes 41h are formed in the overlapping peripheral wall 41. The bolt holes 41h are through holes that penetrate the overlapping peripheral wall 41. Two bolt holes 41h are formed in each of the pair of first overlapping peripheral wall portions 43. Each bolt hole 41h communicates with a bolt hole 31h in the shielding peripheral wall 31. A bolt B, which is inserted into the bolt hole 31h in the shielding peripheral wall 31, is inserted into each bolt hole 41h. A nut N is attached to the tip of the bolt B from the inside of the overlapping peripheral wall 41. By fastening the nut N to the bolt B, the first shielding peripheral wall portion 33 and the first overlapping peripheral wall portion 43 are fastened together in the thickness direction.

[0042] As shown in Fig. 3, introduction holes 40h are formed in the overlapping peripheral wall 41 and the overlapping bottom wall 42. The introduction holes 40h formed in the overlapping peripheral wall 41 are through-holes that penetrate the overlapping peripheral wall 41. The introduction holes 40h formed in the overlapping bottom wall 42 are through-holes that penetrate the overlapping bottom wall 42. The introduction holes 40h are formed in four locations in the overlapping bottom wall 42: two in each of the pair of first overlapping peripheral wall portions 43 and two in each of the pair of second overlapping peripheral wall portions 44. The introduction holes 40h in the overlapping peripheral wall 41 communicate with the introduction holes 30h in the shielding peripheral wall 31. The introduction holes 40h in the overlapping bottom wall 42 communicate with the introduction holes 30h in the shielding bottom wall 32.

[0043] Each introduction hole 40h is closed by a removable closing member 40j. Similar to the closing member 30j that closes the introduction hole 30h of the shielding unit 30, the closing member 40j can be easily removed from the introduction hole 40h to use the introduction hole 40h for inserting a cable or the like.

[0044] 1 and 3, an insertion hole 42h is formed in the overlapping bottom wall 42. The insertion hole 42h is a through-hole that penetrates the overlapping bottom wall 42. The insertion hole 42h is formed, for example, in the center of the overlapping bottom wall 42. The insertion hole 42h communicates with the insertion hole 42h in the shielding bottom wall 32. For example, when the suspension bolt 14 is inserted into the insertion hole 32h in the shielding bottom wall 32, the suspension bolt 14 is inserted into the interior of the overlapping portion 40 through the insertion hole 42h in the overlapping bottom wall 42.

[0045] <Mounting part> As shown in Fig. 2, the attachment portion 50 is separate from the main body portion 20. The leakage prevention device 10 has two attachment portions 50. The two attachment portions 50 are spaced apart from each other in the first direction Y. The main body portion 20 is located between the two attachment portions 50 in the first direction Y.

[0046] The mounting portion 50 extends along the back surface 11b of the ceiling wall 11, which serves as a wall material. The mounting portion 50 is a flat, rectangular plate when viewed in the vertical direction X. The mounting portion 50 extends in a first direction Y, which is an extension direction away from the main body 20. The mounting portion 50 is located closer to the bottom wall 22 than the tip 21a of the peripheral wall 21. More specifically, the mounting portion 50 is located higher than the tip 21a of the peripheral wall 21 in the vertical direction X. As a result, the mounting portion 50 is spaced apart from the back surface 11b of the ceiling wall 11.

[0047] The mounting portion 50 has a mounting hole 50h. The mounting hole 50h is a through-hole that penetrates the mounting portion 50 in the up-down direction X. In this embodiment, the mounting hole 50h is an elongated hole that extends in the first direction Y. A plurality of mounting holes 50h may be formed in the mounting portion 50, spaced apart from each other in the second direction Z. In this embodiment, three mounting holes 50h are formed in the mounting portion 50.

[0048] As shown by the dashed dotted line in Figure 2, the mounting portion 50 is attached to the second elongated member 13b by bolts B inserted into the mounting holes 50h. Therefore, the mounting portion 50 is attached to the second elongated member 13b, which serves as a fixing member to which the ceiling wall 11, which serves as a wall material, is fixed. The bolts B may be inserted into all or some of the mounting holes 50h formed in the mounting portion 50. The drawing illustrates an example in which the bolts B are inserted into two of the three mounting holes 50h formed in the mounting portion 50.

[0049] 3 and 5, the mounting portion 50 is attached to the second elongated member 13b in a position along the upper surface 13c of the second elongated member 13b. The ceiling wall 11, which serves as a wall material, is fixed to the side of the second elongated member 13b opposite the upper surface 13c. In other words, the mounting portion 50 can be attached to the side of the second elongated member 13b other than the side to which the ceiling wall 11 is fixed, with the tip 21a of the peripheral wall 21 abutting against the back surface 11b of the ceiling wall 11.

[0050] As shown in FIG. 3, the mounting portion 50 has an attachment portion 51 that is attached to the main body portion 20. The attachment portion 51 has an elongated shape that extends along the outer surface of the peripheral wall 21. The attachment portion 51 has a rectangular flat plate shape. The attachment portion 51 has a through hole 51h. The through hole 51h is a through hole that passes through the attachment portion 51 in the thickness direction of the attachment portion 51. In this embodiment, the through hole 51h is an elongated hole that extends in the vertical direction X. A plurality of through holes 51h may be formed in the attachment portion 51, spaced apart from each other in the second direction Z. In this embodiment, two through holes 51h are formed in the attachment portion 51.

[0051] A bolt B is inserted into the through hole 51h. With the attachment portion 51 positioned outside the peripheral wall 21, the bolt B is inserted into the through hole 51h. The bolt B is inserted into the through hole 51h, the bolt hole 31h in the first shielding peripheral wall portion 33, and the bolt hole 41h in the first overlapping peripheral wall portion 43, and a nut N is attached to the bolt B from the inside of the overlapping peripheral wall 41, thereby attaching the attachment portion 51 to the main body portion 20. Therefore, the attachment portion 51 is attached to the overlapping portion 40. The bolt B functions as an attachment bolt that attaches to the overlapping portion 40.

[0052] As shown in FIG. 6 , the insertion position of the bolt B in the through hole 51h can be changed within the dimensional range of the through hole 51h in the up-down direction X. By changing the insertion position of the bolt B in the through hole 51h, the position of the attachment part 51 relative to the main body 20 can be shifted in the up-down direction X. When the position of the attachment part 51 is shifted in the up-down direction X, the mounting part 50 is also shifted in the up-down direction X. Therefore, the attachment part 51 can be attached to the main body 20 by changing the position of the attachment part 50 relative to the opening 25 to a different position shifted in the up-down direction X. The up-down direction X is also the opposing direction between the opening 25 and the bottom wall 22.

[0053] An example of a mounting portion 50 at a different position from the mounting portion 50 of the present embodiment is shown in FIG. 6 by a two-dot chain line. This example mounting portion 50 is located at a position shifted upward from the position of the mounting portion 50 of the present embodiment. In the example mounting portion 50, the bolt B is inserted into the through hole 51h at a different position from that of the embodiment, so that the relative position of the attachment portion 51 with respect to the bolt B is shifted upward from that of the mounting portion 51 of the embodiment. The example mounting portion 50 is at the same height as the upper surface 13d of the first elongated member 13a. Specifically, the distance between the rear surface 11b of the ceiling wall 11 and the lower surface of the example mounting portion 50 in the vertical direction X is the same dimension as the distance between the rear surface 11b of the ceiling wall 11 and the upper surface 13d of the first elongated member 13a in the vertical direction X. Therefore, the example mounting portion 50 can be placed on the upper surface 13d of the first elongated member 13a. When placing the attachment part 50 on the upper surface 13d of the first elongated material 13a, the attachment part 50 is positioned above the first elongated material 13a by, for example, displacing the leakage prevention device 10 so that the extension direction of the attachment part 50 from the main body part 20 is the second direction Z. Furthermore, although not shown in the drawings, the position of the attachment part 50 may be changed by turning the attachment part 50 upside down.

[0054] The attachment portion 51 can be attached to the main body 20 by changing the installation position of the mounting portion 50 relative to the opening 25 to at least two positions offset in the vertical direction X so that the mounting portion 50 can be placed on the top surfaces 13c, 13d of the first elongated member 13a and the second elongated member 13b, respectively. Because the through hole 51h is an elongated hole extending in the vertical direction X, the installation position of the mounting portion 50 can be continuously changed in the vertical direction X, including multiple positions different from the two positions, by changing the insertion position of the bolt B within the dimensional range of the through hole 51h in the vertical direction X. The mounting portion 50 can be attached to the second elongated member 13b while placed on the top surface 13c of the second elongated member 13b, and can be attached to the first elongated member 13a while placed on the top surface 13d of the first elongated member 13a.

[0055] 7 shows an example of a second elongated member 13b located at a different position from the second elongated member 13b of this embodiment, indicated by a two-dot chain line. In this example, the second elongated member 13b is located at a position shifted in the first direction Y from the position of the second elongated member 13b of this embodiment. Because the mounting hole 50h is an elongated hole extending in the first direction Y, the insertion position of the bolt B (FIG. 2) into the mounting hole 50h can be changed within the dimensional range of the mounting hole 50h in the first direction Y. In this way, by inserting the bolt B into the mounting hole 50h at different positions in the first direction Y, the mounting portion 50 can be attached by the bolt B to the second elongated member 13b located at different positions in the first direction Y.

[0056] [Operation of the embodiment] Next, the operation of this embodiment will be described. The leak prevention device 10 may be installed before or after the ceiling wall 11, which serves as a wall material, is fixed to the second elongated member 13b, which serves as a fixing member. When the leak prevention device 10 is installed before the ceiling wall 11 is fixed to the second elongated member 13b, the leak prevention device 10 is positioned at a position where the tip 21a of the peripheral wall 21 is expected to abut against the back surface 11b of the ceiling wall 11. When the leak prevention device 10 is installed after the ceiling wall 11 is fixed to the second elongated member 13b, the leak prevention device 10 is positioned so that the tip 21a of the peripheral wall 21 abuts against the back surface 11b of the ceiling wall 11.

[0057] When installing the leakage prevention device 10, the mounting portion 50 is placed on the upper surface 13c of the second elongated member 13b. In this state, the mounting portion 50 is attached to the second elongated member 13b with bolts B, thereby attaching the mounting portion 50 to the side of the second elongated member 13b different from the side to which the ceiling wall 11 is fixed. The leakage prevention device 10 is attached to the second elongated member 13b. If the leakage prevention device 10 is installed before the ceiling wall 11 is fixed to the second elongated member 13b, the tip 21a of the peripheral wall 21 will abut against the back surface 11b of the ceiling wall 11 by fixing the ceiling wall 11 to the second elongated member 13b. When the leakage prevention device 10 is installed in this manner, the leakage prevention device 10 covers the through hole 11h formed in the ceiling wall 11 from the back side of the ceiling wall 11, thereby preventing radiation from leaking through the through hole 11h.

[0058] [Effects of the embodiment] According to the above embodiment, the following effects can be obtained. (1) The leakage prevention device 10 has an attachment portion 50 that is attached to the second elongated member 13b as a fixing member. The ceiling wall 11 as a wall material is fixed to the second elongated member 13b. The attachment portion 50 can be attached to the second elongated member 13b with the tip 21a of the peripheral wall 21 abutting the back side surface 11b. Because the attachment portion 50 is attached to the second elongated member 13b, the leakage prevention device 10 can be installed on the second elongated member 13b. Therefore, the leakage prevention device 10 can be installed even before the ceiling wall 11 is installed.

[0059] (2) The main body 20 includes a shielding portion 30 made of a material that prevents radiation leakage and an overlapping portion 40 made of a material that is more rigid than the shielding portion 30. Therefore, compared to when the entire main body 20 is made of the shielding portion 30, the rigidity of the main body 20 is increased, thereby suppressing deformation of the main body 20. Furthermore, when attaching the leakage prevention device 10 to the second elongated member 13b as a fixing member, the main body 20 may interfere with the second elongated member 13b. In this case, processing such as cutting a portion of the peripheral shielding wall 31 from the tip 31a of the peripheral shielding wall 31 or bending a portion of the tip 31a of the peripheral shielding wall 31 is required to separate the tip 31a of the peripheral shielding wall 31 from the second elongated member 13b. Because the tip 31a of the peripheral shielding wall 31 that is to be processed is exposed from the overlapping portion 40, processing of the overlapping portion 40 is not required when processing the peripheral shielding wall 31, improving workability.

[0060] (3) The peripheral shielding wall 31 is provided in advance with a notch 36 extending from the tip 31a of the peripheral shielding wall 31 toward the bottom wall 22. Therefore, even if the notch 36 is required in the tip 31a of the peripheral shielding wall 31 in order to prevent the tip 31a of the peripheral shielding wall 31 from interfering with the second elongated member 13b serving as a fixing member, it is not necessary to form the notch 36 in the peripheral shielding wall 31 when installing the leakage prevention device 10. This improves the workability of installing the leakage prevention device 10.

[0061] (4) The attachment part 50 is separate from the main body part 20 and includes an attachment part 51 that is attached to the main body part 20. The attachment part 51 can be attached to the main body part 20 by changing the position of the attachment part 50 relative to the opening 25 to a different position offset in the vertical direction X, which is the opposing direction between the opening 25 and the bottom wall 22. When attempting to attach the attachment part 50 to a target member other than the second elongated member 13b, such as the first elongated member 13a, the position of the target member in the vertical direction X may differ from that of the second elongated member 13b. Even in this case, the attachment part 50 can be attached to a target member other than the second elongated member 13b by changing the position of the attachment part 51 to a different position offset in the vertical direction X. Therefore, the leakage prevention device 10 can be attached to a target member other than the second elongated member 13b.

[0062] (5) The mounting portion 50 extends in the first direction Y, which is the direction in which the mounting portion 50 extends away from the main body portion 20. Therefore, compared to when the mounting portion 50 has a flange-like shape extending from the main body portion 20, the mounting surface of the target member to which the mounting portion 50 is attached can be made smaller. Therefore, the degree of freedom in the mounting location of the mounting portion 50 can be improved.

[0063] (6) The attachment portion 51 is attached to the overlapping portion 40, which is made of a material that is more rigid than the shielding portion 30. Therefore, compared to when the attachment portion 51 is attached only to the shielding portion 30, the attachment portion 50 can be attached to the main body 20 in a more stable position.

[0064] [Example of change] The above embodiment can be modified as follows: The above embodiment and the following modifications can be combined with each other within the scope of technical compatibility.

[0065] The insertion holes 32h may be omitted from the shielding bottom wall 32. The insertion holes 42h may be omitted from the overlapping bottom wall 42. The blocking members 40j do not necessarily have to be provided in advance for some or all of the introduction holes 40h formed in the overlapping portion 40.

[0066] Some or all of the introduction holes 30h formed in the shielding portion 30 may be omitted. Some or all of the introduction holes 40h formed in the overlapping portion 40 may be omitted. The overlapping portion 40 may overlap the outside of the shielding portion 30. In this case, the overlapping portion 40 overlaps the outside of the peripheral shielding wall 31 and the bottom shielding wall 32. However, assembling the main body 20 becomes easier if the bendable shielding portion 30 is deformed and arranged so as to be wrapped around the outside of the overlapping portion 40, which is less likely to deform.

[0067] When the overlapping portion 40 overlaps the outside of the shielding portion 30, the bolt B serving as the attachment bolt may be screwed in so as to penetrate the overlapping portion 40 but not the shielding portion 30. In this case, a bolt hole 41h is formed in the overlapping portion 40, and the bolt hole 31h is omitted from the shielding portion 30.

[0068] The bolts B may be inserted into only some of the plurality of bolt holes 31h formed in the shielding portion 30. The bolts B may be inserted into only some of the plurality of bolt holes 41h formed in the overlapping portion 40. In these cases, the bolt holes 31h, 41h into which the bolts B are not inserted are covered by, for example, sealing the openings to prevent radioactive leakage.

[0069] The shielding portion 30 may be made of a flexible material. In this case, for example, if a portion of the rear surface 11b of the ceiling wall 11 is shaped to protrude upward relative to the surrounding area, the shielding portion 30 may be deformed so that the portion of the peripheral shielding wall 31 that abuts against the upward-protruding portion of the rear surface 11b bends along the cutout 36.

[0070] The formation of the notches 36 in the peripheral shielding wall 31 may be omitted. The attachment portion 51 may have a plurality of through holes 51h formed along the vertical direction X, which is the opposing direction between the opening 25 and the bottom wall 22. In this case, by changing the through hole 51h through which the bolt B serving as an attachment bolt is inserted, the insertion position of the bolt B into the through hole 51h can be varied in the vertical direction X. Therefore, the attachment portion 51 can be attached to the main body 20 by varying the position of the attachment portion 50 relative to the opening 25 to a different position displaced in the vertical direction X. Note that some or all of the plurality of through holes 51h may be elongated holes extending in the vertical direction X. This is desirable because the insertion position of the bolt B into the through hole 51h can be varied continuously in the vertical direction X.

[0071] The through hole 51h formed in the attachment portion 51 may be only one hole large enough to allow one bolt B to be inserted therethrough. Alternatively, the through hole 51h may be omitted from the attachment portion 51. In this case, the attachment portion 51 may be attached to the main body 20 by means other than the bolt B. For example, the attachment portion 51 may be attached to the main body 20 by an adhesive. For example, the attachment portion 51 may have one or more nails extending toward the main body 20, so that the attachment portion 51 can be attached to the main body 20 by the nails.

[0072] The attachment portion 51 may be omitted from the mounting portion 50. In other words, the attachment portion 50 may be attached to the main body 20 by a configuration other than the attachment portion 51 as long as it is located closer to the bottom wall 22 than the tip 21a of the peripheral wall 21 and can be attached to the second elongated member 13b serving as a fixing member.

[0073] The attachment portion 50 and the main body portion 20 may be integral. For example, the attachment portion 50 and the overlapping portion 40 may be an integral member. For example, the attachment portion 50 and the shielding portion 30 may be an integral member.

[0074] The mounting holes 50h may be formed in a plurality along the first direction Y, which is a direction away from the main body 20 and which is the direction in which the mounting portion 50 extends from the main body 20. In this case, by changing the mounting holes 50h through which the bolts B are inserted, the insertion positions of the bolts B into the mounting holes 50h can be varied in the first direction Y. Therefore, the mounting portion 50 can be attached to second elongated members 13b serving as fixing members at different positions in the first direction Y. Note that by varying the insertion positions of the bolts B into the mounting holes 50h in the first direction Y, the mounting positions of the mounting portions 50 relative to the second elongated members 13b at the same position can be varied in the first direction Y. Furthermore, some or all of the multiple mounting holes 50h may be elongated holes extending in the first direction Y, which is the direction in which the mounting portion 50 extends from the main body 20. In this case, by varying the insertion position of the bolt B relative to the mounting hole 50h steplessly in the first direction Y, it is possible to flexibly accommodate the amount of separation between the main body 20 and the second elongated member 13b serving as the fixing member.

[0075] The mounting hole 50h formed in the mounting portion 50 may be only one hole large enough to insert one bolt B. Alternatively, the mounting hole 50h may be omitted from the mounting portion 50. In this case, the mounting portion 50 may be attached to the second elongated member 13b by means other than the bolt B. For example, the mounting portion 50 may be attached to the second elongated member 13b by adhesive. The mounting portion 50 may have one or more nails extending toward the ceiling wall 11, which serves as a wall material, so that the mounting portion 50 can be attached to the second elongated member 13b by the nails.

[0076] The portion of the overlapping portion 40 that is located higher than the height of the upper surface 13c of the second elongated member 13b may be part of the overlapping portion 40. Only part of the overlapping portion 40 may be located closer to the bottom wall 22 than the tip 31a of the peripheral shielding wall 31.

[0077] The tip 31 a of the shielding peripheral wall 31 and the tip 41 a of the overlapping peripheral wall 41 may be located at the same position in the up-down direction X, which is the opposing direction between the opening 25 and the bottom wall 22. The tip 31 a of the shielding peripheral wall 31 may be located closer to the bottom wall 22 than the tip 41 a of the overlapping peripheral wall 41.

[0078] The peripheral wall 21 may be a cylindrical shape other than a rectangle, such as a cylindrical shape. The bottom wall 22 may be a flat plate shape other than a rectangle, such as a circular flat plate shape. The bottom wall 22 may have a shape other than a flat plate shape. The shapes of the shielding peripheral wall 31 and the overlapping peripheral wall 41 may be changed to match the shape of the peripheral wall 21. The shapes of the shielding bottom wall 32 and the overlapping bottom wall 42 may be changed to match the shape of the bottom wall 22.

[0079] The overlapping bottom wall 42 may be omitted from the overlapping portion 40 . The main body 20 does not need to be differentiated between the shielding portion 30 and the overlapping portion 40. For example, the overlapping portion 40 may be omitted from the main body 20. In short, the main body 20 may be a bottomed box-like body including a cylindrical peripheral wall 21 that forms an opening 25 at the tip 21a, the opening 25 being large enough to surround the through-hole 11h, and a bottom wall 22 that faces the opening 25, and is formed from a material that prevents radiation leakage.

[0080] The shape of the through-hole 11h when viewed in the vertical direction X is not limited to a rectangular shape. For example, the through-hole 11h may have a circular shape when viewed in the vertical direction X. The wall material may be a side wall or a floor wall.

[0081] [Note] Next, the technical ideas that can be understood from the above-described embodiment and modified examples will be additionally described below. [Embodiment 8] The main body portion is formed from a material that prevents leakage of the radiation, and has a bottomed, box-shaped shielding portion with a cylindrical shielding peripheral wall and a shielding bottom wall, and a cylindrical overlapping portion that is formed from a material that is more rigid than the shielding portion and overlaps the shielding peripheral wall, the peripheral wall includes the shielding peripheral wall and the overlapping portion, the bottom wall includes the shielding bottom wall, the opening is formed at the tip of the shielding peripheral wall, and the attachment portion has a through hole through which an attachment bolt that attaches to the overlapping portion is inserted. This is a leakage prevention device described in [Embodiment 4].

[0082] [Aspect 9] The main body portion is formed from a material that prevents leakage of the radiation, and has a bottomed, box-shaped shielding portion with a cylindrical shielding peripheral wall and a shielding bottom wall, and a cylindrical overlapping portion that is formed from a material that is more rigid than the shielding portion and overlaps the shielding peripheral wall, the peripheral wall includes the shielding peripheral wall and the overlapping portion, the bottom wall includes the shielding bottom wall, the opening is formed at the tip of the shielding peripheral wall, and the attachment portion has a through hole through which an attachment bolt that attaches to the overlapping portion is inserted, an installation structure for a leakage prevention device described in any one of [Aspect 5] to [Aspect 7].

[0083] According to the configurations described in [Embodiment 8] and [Embodiment 9], the attachment portion can be easily attached to the main body portion by attaching the attachment bolt inserted into the through hole to the overlapping portion. [Aspect 10] A leakage prevention device described in any one of [Aspect 1] to [Aspect 4] and [Aspect 8], wherein the mounting portion extends in an extension direction away from the main body portion and can be attached to the fixing member at a different position in the extension direction.

[0084] [Aspect 11] An installation structure for a leakage prevention device described in any one of [Aspects 5] to [Aspect 7] and [Aspect 9], wherein the mounting portion extends in an extension direction away from the main body portion and can be attached to the fixing member at a different position in the extension direction.

[0085] According to the configurations described in [Aspect 10] and [Aspect 11], the attachment position of the attachment part to the fixed member can be selected from among the different positions in the extension direction from the installation position of the main body part. [Explanation of symbols]

[0086] X...vertical direction, 10...leak prevention device, 11...ceiling wall, 11b...rear side, 11h...through hole, 13...ceiling underlayment material, 13a...first elongated member, 13b...second elongated member, 13c, 13d...top surface, 20...main body, 21...circumferential wall, 21a, 31a, 41a...tip, 22...bottom wall, 25...opening, 30...shielding portion, 31...shielding peripheral wall, 32...shielding bottom wall, 36...notch, 40...overlap portion, 50...mounting portion, 51...attachment portion.

Claims

1. A leakage prevention device that covers a through-hole formed in a wall material from a back side of the wall material to prevent radiation from leaking from the through-hole, a main body portion having a bottomed box shape including a cylindrical peripheral wall that forms an opening at a tip end thereof, the opening being large enough to surround the through hole, and a bottom wall that faces the opening, the main body portion being formed containing a material that prevents leakage of the radiation; a mounting portion located closer to the bottom wall than the tip of the peripheral wall and attached to a fixing member to which the wall material is fixed, The attachment portion can be attached to the fixing member with the tip of the peripheral wall abutting against the rear surface of the wall material.

2. The main body portion is a bottomed box-shaped shielding portion formed of a material that prevents leakage of the radiation and having a cylindrical shielding peripheral wall and a shielding bottom wall; a cylindrical overlapping portion formed of a material having higher rigidity than the shielding portion and overlapping the shielding peripheral wall, the peripheral wall includes the shielding peripheral wall and the overlapping portion, the bottom wall includes the shielding bottom wall; The opening is formed at a tip of the peripheral shielding wall, The leakage prevention device according to claim 1 , wherein at least a portion of the overlapping portion that faces the shielding portion is located closer to the bottom wall than the tip of the shielding peripheral wall.

3. The leakage prevention device according to claim 2, wherein the peripheral shielding wall is provided with a notch extending from a tip of the peripheral shielding wall toward the bottom wall.

4. the attachment portion is separate from the main body portion and includes an attachment portion attached to the main body portion, The leak prevention device according to any one of claims 1 to 3, wherein the attachment portion can be attached to the main body portion by changing the position of the attachment portion relative to the opening to a different position shifted in the opposing direction between the opening and the bottom wall.

5. A leakage prevention device installation structure for installing the leakage prevention device according to claim 4, the fixing member is a second elongated member of a ceiling underlayment material that is composed of a first elongated member and a second elongated member that overlaps the first elongated member in the vertical direction, intersects the first elongated member in the horizontal direction, and is positioned below the first elongated member; the wall material comprises a ceiling wall fixed to the second elongated member, The main body is provided with the opening facing downward, The attachment portion is an installation structure for a leakage prevention device that can be attached to the main body portion by changing the installation position of the attachment portion relative to the opening to at least two positions offset in the vertical direction so that the attachment portion can be placed on the upper surfaces of each of the first elongated material and the second elongated material.

6. The main body portion is a bottomed box-shaped shielding portion formed of a material that prevents leakage of the radiation and having a cylindrical shielding peripheral wall and a shielding bottom wall; a cylindrical overlapping portion formed of a material having higher rigidity than the shielding portion and overlapping the shielding peripheral wall, the peripheral wall includes the shielding peripheral wall and the overlapping portion, the bottom wall includes the shielding bottom wall; The opening is formed at a tip of the peripheral shielding wall, The leakage prevention device installation structure according to claim 5, wherein the overlapping portion is located entirely at a position higher than the height of the upper surface of the fixing member and is located closer to the bottom wall than the tip of the shielding peripheral wall.

7. The installation structure of a leakage prevention device as described in claim 6, wherein the shielding peripheral wall has a notch pre-formed therein, the notch extending from the tip of the shielding peripheral wall toward the bottom wall, the notch having a length equal to or greater than the vertical height of the second elongated member.

Images