JP6239290B2 - Radioactive substance storage container and method for manufacturing radioactive substance storage container - Google Patents

Description

  The present invention relates to a radioactive substance storage container and a method for manufacturing a radioactive substance storage container.

  Radioactive waste generated in a nuclear power plant nuclear reactor or the like is stored in a radioactive material storage container, transported to a storage facility or a reprocessing facility, and stored or reprocessed. As disclosed in Patent Document 1, such a radioactive substance storage container has a cylindrical body with a bottom with an open top and a plurality of cells that can individually store a plurality of radioactive substances. It is comprised from the basket and the cover part fixed to the upper part of a trunk | drum. Non-Patent Document 1 discloses a structure that suppresses corrosion by a stainless steel boss or aluminum spraying at the lid.

JP 2013-104793 A Nuclear Fuel Cycle Safety Subcommittee Interim Storage Working Group Study Meeting on Welding of Spent Fuel Storage Facility (2nd) Handout Material 2-2

  For example, if at least a part of the lid portion is corroded (rusted) by contact with water, the performance of the radioactive substance storage container may be deteriorated. As one of the conventional technologies for suppressing the occurrence of corrosion, a technology that forms part of the lid that is highly likely to corrode with stainless steel members and the other part with carbon steel members There is. Costs can be reduced by making a part of the lid part stainless steel. However, in the prior art, it is necessary to join (weld) a stainless steel member and a carbon steel member in the production of the lid, which increases the number of man-hours including distortion correction at the time of joining and the work cost. May lead to an increase. For example, when manufacturing a lid having a hole, after welding a carbon steel member and a stainless steel member, a hole is formed in the stainless steel member, and then the carbon steel member is made of aluminum. The number of man-hours increases in the procedure of performing the rust prevention treatment by a technique such as thermal spraying or painting. Moreover, the joint part (welded part) of two members deteriorates by the difference in the thermal expansion coefficient of two members, etc., and the intensity | strength of a cover part may fall. As a result, the performance of the radioactive substance storage container may be deteriorated. Also, in rust prevention treatment such as aluminum spraying, the thickness of the protective film is increased for rust prevention, so the structure thickness of the lid part that maintains strength may be relatively thin, and the strength may decrease. .

  An object of this invention is to provide the radioactive substance storage container by which the fall of performance is suppressed. Another object of the present invention is to provide a method for manufacturing a radioactive substance storage container in which an increase in work cost is suppressed and a decrease in the performance of the radioactive substance storage container is suppressed.

  In order to achieve the above object, a radioactive substance storage container according to the present invention includes a trunk portion that stores a radioactive substance, and a lid portion that closes an opening of the trunk portion, and the lid portion is a single unit. A lid body formed with a hole, and at least a part of an inner surface of the hole and an outer surface of the lid body disposed around the opening of the hole, and corroding the lid body And a protective film for suppressing.

  According to this radioactive substance storage container, since the lid body is a single member, a decrease in the strength of the lid body is suppressed. Further, since the protective film is provided on at least a part of the inner surface of the hole and the outer surface of the lid body arranged around the opening of the hole which is highly likely to corrode, the occurrence of corrosion (rust) in the lid body is suppressed. . Therefore, the deterioration of the performance of the radioactive substance storage container is suppressed.

  In the radioactive substance storage container according to the present invention, the protective film may include a metal film formed by electroless plating. Thereby, a protective film is smoothly formed also in the inner surface of the hole with high possibility of corrosion.

  In the radioactive substance storage container according to the present invention, the lid portion is disposed between the gasket and the lid body and the gasket, has a contact surface with which the gasket contacts, and is made of a material different from that of the lid body. And a formed support member. Since the support member is formed so as to exhibit a higher sealing function between the gasket and the lid body, the lid portion can obtain a higher sealing function. Thereby, the fall of the performance of a radioactive substance storage container is suppressed.

  The radioactive substance storage container which concerns on this invention WHEREIN: The said cover part may be provided with the gasket and the groove part provided in at least one part of the said outer surface of the said cover main body which the said gasket contacts. By providing the groove in a part of the lid main body that contacts the gasket, the lid can obtain a high sealing function. Thereby, the fall of the performance of a radioactive substance storage container is suppressed.

  In the radioactive substance storage container according to the present invention, the protective film may have a thickness of 50 μm or less. The protective film having a thickness of 50 μm or less provides a sufficient corrosion-inhibiting function, and the protective film having a thickness of 50 μm or less suppresses the size expansion of the lid body. Can be engaged without any special adjustment. Moreover, the strength fall of a cover main body can be suppressed because the thickness of a protective film shall be 50 micrometers or less.

  In order to achieve the above object, a method of manufacturing a radioactive substance storage container according to the present invention includes a trunk part that stores a radioactive substance and a lid part that closes an opening of the trunk part. And a step of forming a hole in the lid body which is a single member, and the lid so as to cover at least a part of the inner surface of the hole and the outer surface of the lid body disposed around the opening of the hole. Forming a protective film capable of suppressing corrosion of the main body and manufacturing the lid.

  According to this method for manufacturing a radioactive substance storage container, since the lid body is a single member and the work of joining two members is omitted, an increase in work cost is suppressed, and a decrease in the strength of the lid body is suppressed. Is done. Further, since the protective film is provided on at least a part of the inner surface of the hole and the outer surface of the lid body arranged around the opening of the hole which is highly likely to corrode, the occurrence of corrosion (rust) in the lid body is suppressed. . Therefore, the deterioration of the performance of the radioactive substance storage container is suppressed.

  The manufacturing method of the radioactive substance storage container according to the present invention may include a procedure of forming the protective film by performing an electroless plating process on the lid body in which the hole is formed. Thereby, a protective film is smoothly formed in each of the inner surface of a hole with high possibility of corroding, and the outer surface of a lid body only by immersing a lid body in a solution (plating solution).

  In the method for manufacturing a radioactive substance storage container according to the present invention, a procedure for connecting a support member made of a material different from the lid body to at least a part of the outer surface of the lid body, and the support member is connected. In this state, the lid body may be subjected to the electroless plating process and the gasket may be disposed so as to contact the contact surface of the support member. Since the support member is formed so as to exhibit a higher sealing function between the gasket and the lid body, the lid portion can obtain a higher sealing function. In addition, since the support member is made of a material that is harder to form the protective film than the lid body, it is suppressed that the protective film is formed on the support member. A sealing function is obtained. Thereby, the fall of the performance of a radioactive substance storage container is suppressed.

  The manufacturing method of the radioactive substance storage container according to the present invention may include a procedure of covering the support member with a mask member in the electroless plating process. Thereby, since a protective film is suppressed from being formed on the support member, a high sealing function can be obtained between the support member and the gasket.

  In the method for manufacturing a radioactive substance storage container according to the present invention, a procedure for serration processing at least a part of the outer surface of the lid main body, and a gasket disposed so as to contact a groove formed in the lid main body by the serration processing And a procedure for performing. By providing the groove in a part of the lid main body that contacts the gasket, the lid can obtain a high sealing function. Thereby, the fall of the performance of a radioactive substance storage container is suppressed.

  In the manufacturing method of the radioactive substance storage container according to the present invention, the electroless plating treatment includes a first electroless plating treatment for forming a first protective film on the lid body, and a top surface of the first protective film. And a second electroless plating process for forming a second protective film. That is, so-called double plating treatment may be performed. Thereby, since a protective film is fully formed, the fall of the performance of a radioactive substance storage container is suppressed.

  According to the radioactive substance storage container according to the present invention, deterioration in performance is suppressed. Moreover, according to the manufacturing method of the radioactive substance storage container which concerns on this invention, the increase in work cost is suppressed and the fall of the performance of a radioactive substance storage container is suppressed.

FIG. 1 is a longitudinal sectional view showing an example of a radioactive substance storage container according to the first embodiment. FIG. 2 is a plan sectional view showing an example of the radioactive substance storage container according to the first embodiment. FIG. 3 is a side cross-sectional view illustrating an example of a lid according to the first embodiment. FIG. 4 is a plan view illustrating an example of a lid according to the first embodiment. FIG. 5 is an enlarged view of a part of FIG. 6 is a cross-sectional view taken along the line CC of FIG. 7 is a cross-sectional view taken along the line DD of FIG. 8 is a cross-sectional view taken along line EE in FIG. 9 is a cross-sectional view taken along line FF in FIG. FIG. 10 is an enlarged view of a part of FIG. Drawing 11 is a mimetic diagram for explaining an example of the manufacturing method of the radioactive substance storage container concerning a 1st embodiment. FIG. 12 is a schematic diagram for explaining an example of a manufacturing method of the radioactive substance storage container according to the first embodiment. Drawing 13 is a mimetic diagram for explaining an example of the manufacturing method of the radioactive substance storage container concerning a 1st embodiment. FIG. 14 is a schematic diagram for explaining an example of a manufacturing method of the radioactive substance storage container according to the first embodiment. FIG. 15 is a diagram illustrating an example of a radioactive substance storage container according to the second embodiment.

  Embodiments according to the present invention will be described below in detail with reference to the drawings. In addition, this invention is not limited by this embodiment. In addition, constituent elements in the following embodiments include those that can be easily replaced by those skilled in the art or those that are substantially the same.

<First Embodiment>
A first embodiment will be described. FIG. 1 is a longitudinal sectional view of a cask as a radioactive substance storage container according to this embodiment, and FIG. 2 is a plan sectional view of a cask as a radioactive substance storage container according to this embodiment.

  A cask 11 as a radioactive substance storage container includes a body portion 12, a lid portion 13, and a basket 14. The trunk portion 12 has a cylindrical shape in which an opening 22 is formed on one side of the trunk body 21, that is, an upper portion, and the bottom portion (blocking portion) 23 is formed on the other side, that is, a lower portion. For example, a spent fuel assembly) can be stored. That is, the trunk body 21 is provided with a cavity 24 inside, and the cavity 24 has a shape matching the outer peripheral shape of the basket 14. The basket 14 has a plurality of cells that individually store a plurality of radioactive substances (not shown). The basket 14 has a basket body 14A as shown in FIG. In the basket body 14A, radioactive substance storage portions 14B as cells arranged parallel to each other at a predetermined interval are formed continuously in the vertical direction. The vertical direction is a direction along the cylindrical central axis of the trunk 12 in the cask 11 and corresponds to the vertical direction of the trunk main body 21. And the bottom part 23 of the trunk | drum main body 21 is couple | bonded by welding or integral shaping | molding, and this trunk | drum main body 21 and the bottom part 23 are forged products made from carbon steel which has a gamma ray shielding function. Stainless steel can also be used for the trunk | drum main body 21 and the bottom part 23 instead of carbon steel. The trunk body 21 and the bottom portion 23 can also be made of cast products such as spheroidal graphite cast iron and carbon steel cast steel.

  The body portion 12 is provided with an outer cylinder 25 with a predetermined gap on the outer peripheral side of the body main body 21, and transfers heat between the outer peripheral surface of the body main body 21 and the inner peripheral surface of the outer cylinder 25. A plurality of copper heat transfer fins 25a are welded at equal intervals in the circumferential direction. The body portion 12 is a resin (neutron shielding material) 26 containing boron or a boron compound which is a polymer material containing a large amount of hydrogen and has a neutron shielding function in the space between the body body 21 and the outer cylinder 25. Is injected and solidified through a pipe (not shown) in a fluidized state.

  The body 12 may have a bottom plate 28 connected to the lower side of the bottom 23 with a plurality of connecting plates 27 with a predetermined gap, and a resin (neutron) in a space between the connecting plate 27 and the bottom plate 28. A shielding material 29 is provided. The connecting plate 27 may not be provided. Furthermore, the trunnion 41 is being fixed to the trunk | drum 12 in the predetermined position in an outer peripheral part.

  The lid portion 13 that closes the opening 22 of the trunk body 21 in the trunk portion 12 includes a primary lid portion 31 and a secondary lid portion 32. The primary lid portion 31 has a disk shape, and the secondary lid portion 32 also has a disk shape. As shown in FIG. 1, a resin (neutron shielding material) 33 is sealed in the secondary lid portion 32. The resin 33 may not be sealed in the secondary lid portion 32. The primary lid portion 31 is detachably attached to the upper end portion of the trunk body 21 with bolts 35. The secondary lid portion 32 is also detachably attached to the upper end portion of the trunk body 21 by a bolt (not shown). In addition, an auxiliary shield 34 enclosing a resin may be provided around the lid portion 13.

  Next, the primary lid part 31 will be described in detail. FIG. 3 is a side sectional view of the primary lid 31 according to the present embodiment. FIG. 4 is a plan view of the primary lid 31. FIG. 3 is a cross-sectional view taken along the line AA of FIG. FIG. 5 is an enlarged view of a part of FIG. 6 is a cross-sectional view taken along the line CC of FIG. 7 is a cross-sectional view taken along the line DD of FIG. 8 is a cross-sectional view taken along the line E-E in FIG. 5, and FIG. 9 is a cross-sectional view taken along the line F-F in FIG. 5. FIG. 10 is an enlarged view of a part of FIG.

  The primary lid 31 includes a lid body 50 that is a single member. The lid body 50 is a carbon steel member that shields γ rays. A hole 51 is formed in the lid main body 50. At least a part of the bolt 35 is disposed in the hole 51. The hole 51 is formed in the flange portion 50 </ b> F of the lid main body 50. The primary lid portion 31 is fixed to the upper end portion of the trunk body 21 by the bolts 35. The hole 51 is a through hole formed so as to connect the upper surface 61 and the lower surface 62 of the lid body 50. The lower surface 62 is the lower surface of the flange portion 50F. An upper surface 61 is disposed around the opening 51 </ b> A at the upper end of the hole 51, and a lower surface 62 is disposed around the opening 51 </ b> B at the lower end of the hole 51.

  In the present embodiment, the primary lid portion 31 has a protective film 60 disposed so as to cover each of the inner surface 51H, the upper surface 61, and the lower surface 62 of the hole 51. The protective film 60 suppresses corrosion (rust) of the lid main body 50. The protective film 60 is a metal film and is formed by an electroless plating process. In the present embodiment, the protective film 60 is formed by electroless nickel plating.

  As shown in FIGS. 3 and 5, the primary lid 31 includes a vent valve 42. The lid body 50 has a hole 52 in which the vent valve 42 is disposed. A part of the hole 52 in which the vent valve 42 is disposed may be wider than the other part. The hole 52 is formed so as to connect the upper surface 61 and the lower surface 63 of the lid body 50. An upper surface 61 is disposed around the opening at the upper end of the hole 52, and a lower surface 63 is disposed around the opening at the lower end of the hole 52. A protective film 60 is formed so as to cover each of the inner surface 52H, the upper surface 61, and the lower surface 63 of the hole 52.

  The lid body 50 has a connection surface 64 that connects the inner edge of the lower surface 62 and the outer edge of the lower surface 63, and a side surface 65 of the flange portion 50F. A protective film 60 is formed so as to cover each of the connection surface 64 and the side surface 65.

  As shown in FIG. 6 and the like, the primary lid 31 includes a drain valve 43. The lid body 50 has a hole 53 in which the drain valve 43 is disposed. A part of the hole 53 in which the drain valve 43 is disposed may be wider than the other part. The hole 53 is formed so as to connect the upper surface 61 and the lower surface 63 of the lid body 50. An upper surface 61 is disposed around the opening at the upper end of the hole 53, and a lower surface 63 is disposed around the opening at the lower end of the hole 53. A protective film 60 is formed so as to cover each of the inner surface 53H, the upper surface 61, and the lower surface 63 of the hole 53.

  As shown in FIGS. 5 and 9, a groove 96 and a groove 97 are formed in the inner surface 52 </ b> H of the hole 52. Each of the groove 96 and the groove 97 is formed so as to expand outward in the radial direction with respect to the axis of the hole 52. Each of the inner surface of the groove portion 96 and the inner surface of the groove portion 97 is separated from the outer surface of the vent valve 42. The groove 97 is formed in a part of the inner surface 52 </ b> H including the opening at the upper end of the hole 52. The groove 96 is formed in a part of the inner surface 52 </ b> H farther from the opening at the upper end of the hole 52 than the groove 97. A key may be disposed in the groove 96.

  The inner surface 52 </ b> H of the hole 52 has a recess 98 that connects the groove 97 and the groove 96. The inner surface of the recess 98 is separated from the outer surface of the vent valve 42. The distance between the inner surface of the groove 96 and the outer surface of the vent valve 42 and the distance between the inner surface of the groove 97 and the outer surface of the vent valve 42 are longer than the distance between the inner surface of the recess 98 and the outer surface of the vent valve 42.

  Like the inner surface 52H of the hole 52 in which the vent valve 42 is disposed, the inner surface 53H of the hole 53 in which the drain valve 43 is disposed also has a groove 97 provided in a part of the inner surface 53H including the opening at the upper end of the hole 53. Further, a groove 96 formed in a part of the inner surface 53H away from the opening at the upper end of the hole 53 rather than the groove 97, and a recess 98 connecting the groove 97 and the groove 96 are formed.

  As shown in FIG. 7 and the like, the lid main body 50 is formed with a hole 54 for testing an airtightness inside the cask 11. A plug 44 is disposed in the hole 54. A part of the hole 54 in which the plug 44 is disposed may be wider than the other part. The plug 44 is connected to an airtight leak inspection device for detecting whether or not the gas inside the cask 11 is leaking. A gasket may be disposed between the plug 44 and the lid body 50 (the inner surface 54H of the hole 54). The hole 54 is formed so as to connect the upper surface 61 and the lower surface (outer surface) 62 of the lid body 50. An upper surface 61 is disposed around the opening at the upper end of the hole 54, and a lower surface 62 is disposed around the opening at the lower end of the hole 54. A protective film 60 is formed so as to cover each of the inner surface 54H, the upper surface 61, and the lower surface 62 of the hole 54.

  That is, in this embodiment, the inner surface of the hole (including the inner surface 51H, the inner surface 52H, the inner surface 53H, and the inner surface 54H) and the outer surface (the upper surface 61, the lower surface 62, the lower surface 63, and the connection surface 64) of the lid body 50 outside the hole. And a protective film (nickel film) 60 formed by electroless nickel plating so as to be covered.

  As shown in FIG. 5 and the like, the primary lid 31 has a valve cover plate 45 that covers the vent valve 42. The valve cover plate 45 is fixed to the upper surface 61 of the lid body 50 by bolts 91. As shown in FIG. 6 and the like, the primary lid 31 has a valve cover plate 46 that covers the drain valve 43. The valve cover plate 46 is fixed to the upper surface 61 of the lid body 50 by bolts 92.

  FIG. 10 is an enlarged view of a part of the vent valve 42 and the valve cover plate 45. The valve cover plate 45 is formed with a hole 55 for testing an airtightness inside the cask 11. In the hole 55, a plug 47 to which a pressure sensor for detecting whether or not the gas inside the cask 11 is leaking is connected. A part of the hole 55 in which the plug 47 is disposed may be wider than the other part. A gasket may be disposed between the plug 47 and the lid main body 50 (the inner surface 55H of the hole 55). The hole 55 is formed so as to connect the upper surface and the lower surface of the valve cover plate 45. The upper surface of the valve cover plate 45 is disposed around the opening at the upper end of the hole 55, and the lower surface of the valve cover plate 45 is disposed around the opening at the lower end of the hole 55.

  The valve cover plate 45 may be made of carbon steel. The protective film 60 may be formed on each of the inner surface 55H of the hole 55 and the outer surface (including the upper surface, the lower surface, and the side surface) of the valve cover plate 45.

  Similar to the valve cover plate 45, the valve cover plate 46 is formed with a hole 56 for testing an airtightness inside the cask 11. A plug 48 to which a pressure sensor for detecting whether or not the gas inside the cask 11 is leaking is connected to the hole 56. A part of the hole 56 in which the plug 48 is disposed may be wider than the other part. A gasket may be disposed between the plug 48 and the lid body 50 (the inner surface 56H of the hole 56). The hole 56 is formed so as to connect the upper surface and the lower surface of the valve cover plate 46. The upper surface of the valve cover plate 46 is disposed around the opening at the upper end of the hole 56, and the lower surface of the valve cover plate 46 is disposed around the opening at the lower end of the hole 56.

  The valve cover plate 46 may be made of carbon steel. The protective film 60 may be formed on each of the inner surface 56H of the hole 56 and the outer surface (including the upper surface, the lower surface, and the side surface) of the valve cover plate 46.

  In the present embodiment, the primary lid portion 31 has a plurality of gaskets 70. The gasket 70 is a metal gasket. The gasket 70 ensures the airtightness (sealing property) inside the cask 11.

  For example, as shown in FIGS. 3, 5, 6, and 7, a gasket 70 </ b> A is disposed between the lid body 50 (flange portion 50 </ b> F) and the trunk body 21. At least a part of the gasket 70 </ b> A is disposed in the recess 71 provided in the lower surface 62. As shown in FIG. 5, a gasket 70B is disposed between the vent valve 42 and the hole 52 (inner surface 52H). At least a part of the gasket 70 </ b> B is disposed in a recess provided on the lower surface of the vent valve 42. A gasket 70 </ b> C is disposed between the valve cover plate 45 and the upper surface 61. The gasket 70 </ b> C is disposed in a recess 72 provided on the lower surface of the valve cover plate 45. As shown in FIG. 6 etc., gasket 70D is arrange | positioned between the drain valve 43 and the hole 53 (inner surface 53H). At least a part of the gasket 70 </ b> D is disposed in a recess provided on the lower surface of the drain valve 43. A gasket 70 </ b> E is disposed between the valve cover plate 46 and the upper surface 61. The gasket 70 </ b> E is disposed in a recess 73 provided on the lower surface of the valve cover plate 46.

  In the present embodiment, the primary lid portion 31 is disposed between the lid main body 50 and the gasket 70 and has a support member 80 formed of a material different from that of the lid main body 50. The support member 80 is fixed to the lid body 50. The support member 80 is joined to the lid body 50 by welding, for example. The support member 80 has a contact surface with which the gasket 70 can contact. The support member 80 is disposed so as to contact at least a part of the gasket 70. The contact surface of the support member 80 that contacts the gasket 70 may be referred to as a sealing surface or a sheet surface. As described above, in the present embodiment, the lid body 50 is made of carbon steel. In the present embodiment, the support member 80 is made of stainless steel.

  For example, as shown in FIGS. 3, 5, 6, and 7, the support member 80A is disposed between the lid body 50 (flange portion 50F) and the gasket 70A. The inner surface of the recess 71 includes the lower surface (contact surface) of the support member 80A. The support member 80A is disposed so as to contact the gasket 70A. As shown in FIG. 5 and the like, a support member 80C is disposed between the lid body 50 and the gasket 70C. The support member 80C is disposed so as to contact the gasket 70C. Note that the support member 80 may be disposed between the lid body 50 and the gasket 70B so as to contact the gasket 70B. As shown in FIG. 6 and the like, a support member 80E is disposed between the lid body 50 and the gasket 70E. The support member 80E is disposed so as to contact the gasket 70E. The support member 80 may be disposed between the lid main body 50 and the gasket 70D so as to come into contact with the gasket 70D.

  In the present embodiment, the primary lid portion 31 includes a resin (neutron shielding material) 82 disposed between the lid body 50 and the cover member 81, and a resin disposed between the valve cover plate 45 and the cover member 83. (Neutron shielding material) 84 and a resin (neutron shielding material) 86 disposed between the valve cover plate 46 and the cover member 85. The resin 82 is disposed on the upper surface 61 side of the lid body 50. As shown in FIG. 3 and the like, the cover member 81 is fixed to the lid body 50. As shown in FIG. 5 and the like, the resin 84 is disposed on the upper surface side of the valve cover plate 45. The cover member 83 is fixed to the valve cover plate 45 with bolts 93. As shown in FIG. 6 and the like, the resin 86 is disposed on the upper surface side of the valve cover plate 46. The cover member 85 is fixed to the valve cover plate 46 by bolts 94.

  The cover member 81 may be made of carbon steel. A protective film 60 may be formed on the surface of the cover member 81. Similarly, the cover member 83 and the cover member 85 may each be carbon steel. The protective film 60 may be formed on each of the surface of the cover member 83 and the surface of the cover member 85.

  In the present embodiment, the thickness of the protective film 60 is 50 μm or less. The thickness of the protective film 60 may be, for example, 1 μm or more and 50 μm or less. The thickness of the protective film 60 may be, for example, about 25 μm, about 1 μm, or thinner than 1 μm. A sufficient corrosion-inhibiting function is obtained by the protective film 60 having a thickness of 50 μm or less.

  In the case where the gasket 70A has an annular shape, the diameter of the gasket 70A may be set to 1.4 m or more and 2.4 m or less. Further, with respect to the radial direction of the gasket 70A, the dimension of the support member 80A may be set to 15 mm or more and 40 mm or less. In the case where the gasket 70C (70E) has an annular shape, the diameter of the gasket 70C (70E) may be set to 0.1 m or more and 0.2 m or less. Further, with respect to the radial direction of the gasket 70C (70E), the size of the support member 80C (80E) may be set to 15 mm or more and 40 mm or less.

  As shown in FIG. 5 and the like, the gasket 70A is fixed to the support member 80A by a male screw member 300. The support member 80A is formed with a female screw hole coupled (screwed) to the male screw member 300. The female screw hole is formed in the support member 80 </ b> A and is not formed in the lid main body 50. In other words, with respect to the direction parallel to the axis of the male screw member 300, the size of the support member 80A is larger than the size of the male screw member 300 disposed inside the support member 80A (internal screw hole).

  Next, an example of the manufacturing method of the primary cover part 31 is demonstrated with reference to FIGS. 11 to 13 schematically show the primary lid 31. FIG.

  As shown in FIG. 11, a lid body 50, which is a single member made of carbon steel, is molded. A hole 51, a hole 52, a hole 53, a hole 54, a hole 55, and a hole 56 are formed in the lid main body 50. In the following description, these holes are collectively referred to as holes 500 as appropriate. Further, the inner surfaces of these holes are appropriately referred to as holes 500H. In addition, the surface of the lid body 50 outside the hole 500 is appropriately referred to as an outer surface 600 of the lid body 50. The outer surface 600 of the lid body 50 includes an upper surface 61, a lower surface 62, a lower surface 63, a connection surface 64, and a side surface 65.

  As shown in FIG. 12, a support member 80 made of a material different from that of the lid body 50 is connected to at least a part of the outer surface of the lid body 50. The lid body 50 and the support member 80 are connected by welding. The support member 80 is made of stainless steel.

  As described above, a plurality of support members 80 (such as the support member 80A, the support member 80C, and the support member 80E) are connected to the outer surface 600 of the lid body 50.

  After the hole 500 is formed in the lid body 50 that is a single member and the support member 80 is connected to the lid body 50, the inner surface 500 </ b> H of the hole 500 and the lid body 50 arranged around the opening of the hole 500. A protective film 60 is formed to cover each of the outer surface 600. The protective film 60 has a function of suppressing the corrosion (rust) of the lid body 50 (corrosion suppression function, rust prevention function).

  In the present embodiment, the protective film 60 is formed on at least a part of the inner surface 500 </ b> H of the hole 500 and the outer surface 600 of the lid body 50 by performing electroless nickel plating on the lid body 50 in which the hole 500 is formed.

  As shown in FIG. 13, the lid body 50 is immersed in a solution (plating solution). When the lid body 50 is immersed in the plating solution, the plating solution comes into contact with the inner surface 500H of the hole 500, and the plating solution comes into contact with the outer surface 600 of the lid body 50. Thereby, the protective film 60 is formed on the inner surface 500H of the hole 500 and the outer surface 600 of the lid body 50.

  As described with reference to FIGS. 5 and 9, when the hole 52 has the groove 96, when the lid body 50 is immersed in the plating solution, gas (air) is not discharged from the inside of the groove 96, and plating is performed. There is a possibility that the liquid cannot sufficiently enter the groove 96 and the protective film 60 is not formed on the inner surface of the groove 96. In the present embodiment, since the groove 97 and the recess 98 are provided, the plating solution can flow into the recess 98 from the groove 97 on the upper surface 61 side and enter the groove 96 through the recess 98. That is, the groove 97 and the recess 98 function as a passage through which the plating solution can flow into the groove 96. As a result, the protective film 60 is also smoothly formed on the inner surface of the groove 96.

  In the present embodiment, the lid body 50 is subjected to electroless nickel plating in a state where the support member 80 is connected to the lid body 50. That is, with the lid body 50 and the support member 80 connected, the lid body 50 and the support member 80 are immersed in the plating solution. The lid body 50 is made of carbon steel, and the support member 80 is made of stainless steel. In the electroless nickel plating process, the plating film (metal film) is formed on the surface of carbon steel, but is hardly formed on the surface of stainless steel. That is, stainless steel is a material in which a plating film is harder to form than carbon steel. Therefore, when the lid body 50 and the support member 80 are immersed in the plating solution in a state where the lid body 50 and the support member 80 are connected, the protective film 60 is formed on the inner surface 500H of the hole 500 and the outer surface 600 of the lid body 50. Thus, the formation of the protective film 60 on the surface (contact surface, seal surface) of the support member 80 is suppressed.

  As shown in FIG. 14, the support member 80 may be covered with a mask member 100 in the electroless nickel plating process. That is, the lid body 50 and the support member 80 may be immersed in the plating solution in a state where the surface of the support member 80 is covered with the mask member 100. By performing electroless nickel plating in a state where the surface of the support member 80 is covered with the mask member 100, the formation of the protective film 60 on the surface (contact surface, seal surface) of the support member 80 is suppressed. The

  The electroless nickel plating process may be performed at least twice. That is, after the electroless nickel plating process for forming the protective film 60 on the lid body 50 is performed, the electroless nickel plating process for further forming the protective film 60 is performed on the protective film 60. Also good. That is, so-called double plating treatment may be performed. Thereby, the protective film 60 is formed so as to cover all of the inner surface 500H of the hole 500 and the outer surface of the lid body 50. For example, when there is a high possibility that defects such as pinholes will occur in the protective film 60 in a single electroless nickel plating process, defects may occur in the protective film 60 by performing the electroless nickel plating process a plurality of times. Is suppressed.

  After the protective film 60 is formed on the lid body 50 by electroless nickel plating, the gasket 70 is disposed so as to contact the surface (contact surface) of the support member 80. Further, the procedure for arranging the vent valve 42 and the drain valve 43 on the lid body 80, the procedure for connecting the valve cover plate 45 and the valve cover plate 46 to the lid body 50, and the resin 82 and the cover member 81 on the lid body 50. A procedure for connecting, a procedure for connecting the resin 84 and the cover member 83 to the valve cover plate 45, a procedure for connecting the resin 86 and the cover member 85 to the valve cover plate 46, and the like are appropriately performed. The primary lid part 31 is manufactured by the above.

  Each of the valve cover plate 45 and the valve cover plate 46 is subjected to electroless nickel plating treatment, and a protective film 60 is formed on each of the valve cover plate 45 and the valve cover plate 46. Then, the valve cover plate 45 and the valve cover The plate 46 may be connected to the lid body 50. The cover member 81 may be connected to the lid body 50 after the cover member 81 is subjected to electroless nickel plating and the protective film 60 is formed on the cover member 81. The cover member 83 may be connected to the valve cover plate 45 after the cover member 83 is subjected to electroless nickel plating and the protective film 60 is formed on the cover member 83. The cover member 85 may be connected to the valve cover plate 46 after the electroless nickel plating process and the protective film 60 is formed on the cover member 85.

  As described above, according to this embodiment, since the lid body 50 is a single member, a decrease in the strength of the lid body 50 is suppressed. That is, when a lid body is manufactured by joining a plurality of members by welding or the like, there is a possibility that the strength of the lid body may be reduced due to deterioration of the joined portion (welded portion). According to the present embodiment, since the lid body 50 is a single member, a decrease in strength is suppressed.

  Further, according to the present embodiment, the lid main body 50 is a single member, and the work of joining a plurality of members is omitted, so that an increase in work cost is suppressed. That is, when manufacturing a lid body by joining a plurality of members by welding or the like, an operation of welding, an operation of correcting distortion generated in the lid body by welding, an operation of flattening the lid body (welded portion), etc. Is required, resulting in an increase in man-hours and an increase in work time, which may increase work costs. According to the present embodiment, since the lid body 50 is a single member, an increase in work cost is suppressed.

  In addition, according to the present embodiment, the protective film 60 is provided on at least a part of the inner surface 500H of the hole 500 and the outer surface 600 of the lid main body 50 disposed around the opening of the hole 500. Rust generation is suppressed. For example, when the primary lid part 31 is processed in water, there is a high possibility that water will remain in the hole 500 that is a narrow part. As a result, there is a high possibility that the inner surface 500H of the hole 500 is corroded (rusted). That is, when the narrow part such as the hole 500 exists in the primary cover part 31, there is a high possibility that the primary cover part 31 is corroded (rusted) by the water remaining in the narrow part. Further, not only residual water but also exposure to the outside air may cause corrosion (rust) of at least a part of the lid 13. In the present embodiment, since the protective film 60 is provided on at least a part of the inner surface 500H of the hole 500 and the outer surface 600 of the lid body 50 disposed around the opening of the hole 50, which is highly likely to corrode, the lid body 51 Corrosion (rust) is suppressed. Therefore, a decrease in the performance of the cask 11 including the lid 13 is suppressed.

  In the present embodiment, the protective film 60 is formed by subjecting the lid body 50 to electroless nickel plating. By simply immersing the lid body 50 in the solution (plating solution), the plating solution flows into the narrow hole 500 and protects the inner surface 500H of the hole 500 and the outer surface 600 of the lid body 50 that are likely to corrode. The film 60 is formed uniformly.

  In the present embodiment, the lid body 50 is made of carbon steel, and carbon steel is less expensive than stainless steel. Since the carbon steel lid body 50 is provided with the protective film 60 having a rust prevention function, an increase in product cost is also suppressed.

  In the present embodiment, a support member 80 made of stainless steel is disposed so that the gasket 70 is in contact with it. The support member 80 can exhibit a higher sealing function between the cover body 50 and the gasket 70. Further, the support member 80 is formed of a material in which the protective film 60 is less likely to be formed than the lid body 50. The support member 80 can exhibit a higher sealing function between the gasket 70 and the protective film 60. In the present embodiment, the formation of the protective film 60 on the support member 80 is suppressed. Therefore, a high sealing function is obtained between the support member 80 and the gasket 70, and the deterioration of the performance of the cask 11 is suppressed. In addition, since the protective film 60 is difficult to be formed on the support member 80, after the lid body 50 and the support member 80 are connected (welded), the protective film 60 is formed on the support member 80 by performing electroless nickel plating. While being formed, the protective film 60 is formed on the lid body 50.

  In the present embodiment, an electroless nickel plating process is performed to form the protective film 60. The protective film (plated film) 60 formed by the plating process has higher hardness, resistance to wear, and resistance to heat than a protective film formed by, for example, a coating process. Therefore, deterioration of the protective film 60 is suppressed. For example, even if the bolt 35 and the protective film 60 come into contact with each other, the deterioration (damage) of the protective film 60 is suppressed. In addition, the protective film 60 formed by the plating process is less likely to be peeled off from the lid body 50 than the protective film formed by the coating process, for example. Therefore, in a state where the cask 11 is placed in the pool (underwater), the pool is prevented from being contaminated.

  In the present embodiment, the case where the protective film 60 is formed on the lid body 50 of the primary lid portion 31 of the lid portion 13 has been described as an example. A protective film 60 may be formed on the lid body of the secondary lid portion 32 of the lid portion 13. When the lid body of the secondary lid portion 32 has a hole, the protective film 60 is smoothly formed on the inner surface of the hole of the lid body. The same applies to the following embodiments.

Second Embodiment
A second embodiment will be described. In the following description, the same or equivalent components as those in the above-described embodiment are denoted by the same reference numerals, and the description thereof is simplified or omitted.

  FIG. 15 is a diagram illustrating a part of the primary lid 31 according to the present embodiment. In the present embodiment, the lid body 50 has a groove (uneven portion) 200 provided on at least a part of the outer surface 600. It arrange | positions so that the gasket 70 may contact the outer surface 600 in which the groove part 200 was provided. The groove part 200 is formed by subjecting at least a part of the outer surface 600 to serration processing.

  In the present embodiment, after the outer surface 600 is serrated to form the groove 200, an electroless nickel plating process is performed. By the electroless nickel plating process, the protective film 60 is uniformly formed in the groove part 200. In a state where the shape of the groove part 200 is maintained, the protective film 60 is formed on the surface of the groove part 200. Then, the gasket 70 is arrange | positioned so that the groove part 200 may be contacted.

  As described above, the groove portion 200 is provided on at least a part of the outer surface 600 with which the gasket 70 contacts, so that a high sealing function can be obtained between the gasket 70 and the outer surface 600 (groove portion 200). In this embodiment, instead of connecting the support member 80 to the lid body 50, a high sealing function can be obtained by forming the groove portion 200 in the lid body 50. The protective film 60 formed by the plating process is hardly peeled off from the lid body 50, and high airtightness can be obtained between the gasket 70 and the groove part 200.

11 Cask (radioactive substance storage container)
12 body portion 13 lid portion 22 opening portion 50 lid body 51, 52, 53, 54, 55, 56 hole 60 protective film 61 upper surface 62 lower surface 63 lower surface 64 connection surface 65 side surface 70 gasket 80 support member 200 groove portion 500 hole 500H inner surface 600 Exterior

Claims (5)

A torso containing radioactive material;
A lid for closing the opening of the trunk,
The lid portion is a single member, and includes a carbon steel lid body in which a hole is formed, and at least a part of the inner surface of the hole and the outer surface of the lid body disposed around the opening of the hole. A protective film that is a metal film formed by an electroless plating process that suppresses corrosion of the lid body, and is fixed to the lid body between the lid body and the gasket. A radioactive substance storage container comprising: a support member made of stainless steel that has a contact surface with which the gasket comes into contact and is different from the lid body.   The radioactive substance storage container according to claim 1, wherein the protective film has a thickness of 50 μm or less. A manufacturing method of a radioactive substance storage container comprising a trunk part that stores a radioactive substance and a lid part that closes an opening part of the trunk part,
A procedure for forming a hole in a carbon steel lid body which is a single member;
A procedure of fixing a support member made of stainless steel, which is a material different from the lid body, to at least a part of the outer surface of the lid body;
The lid body is subjected to electroless plating in a state where the hole is formed and the support member is connected, and at least a part of the inner surface of the hole and the outer surface of the lid body arranged around the opening of the hole is formed. Forming a protective film capable of suppressing corrosion of the lid body so as to cover, and manufacturing the lid portion;
Placing a gasket so as to contact the contact surface of the support member;
Of manufacturing a radioactive substance storage container containing   The manufacturing method of the radioactive substance storage container of Claim 3 including the procedure which covers the said supporting member with a mask member in the said electroless-plating process.   The electroless plating process includes a first electroless plating process for forming a first protective film on the lid body, and a second electroless film for forming a second protective film on the first protective film. The manufacturing method of the radioactive substance storage container of Claim 3 or Claim 4 containing plating processing.

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