JP6216548B2 - Radioactive substance storage basket and radioactive substance storage container - Google Patents

Description

  The present invention relates to a radioactive substance storage basket and a radioactive substance storage container for storing, transporting and storing radioactive waste.

  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. Such a radioactive substance storage container is fixed to the upper part of the trunk part having a cylindrical shape with a bottom with an open top, a basket having a plurality of cells capable of individually accommodating a plurality of radioactive wastes. And a lid portion.

  2. Description of the Related Art Conventionally, for example, a spent fuel storage cask basket described in Patent Document 1 forms a basket lattice by vertically and horizontally intersecting a boron-added stainless steel plate and an aluminum alloy plate.

  Conventionally, for example, a basket structure and a spent fuel cask described in Patent Document 2 are formed by stacking a frame plate made of boron-added aluminum alloy and an inter-frame plate structure made of stainless steel while supporting the frame plate. Together, it constitutes a fuel storage grid.

  Conventionally, for example, the fuel storage basket of the spent fuel transportation and storage container described in Patent Document 3 is a grid of strip-shaped plate materials made of boron-containing stainless steel having neutron absorption performance and rigidity at high temperatures. The assembled first unit basket and a grid-shaped second unit basket in which strip-shaped plate materials made of boron-containing aluminum alloy having neutron absorption performance and good heat conductivity are assembled in a grid shape are stacked and integrated.

  Conventionally, for example, a storage device and a container for storing and / or transporting a nuclear fuel assembly described in Patent Document 4 have a plurality of adjacent housings, each of which has a side wall and a nuclear fuel. The assembly is capable of accepting and the sidewalls are stacked and using crossed slotted structural assemblies, each structural assembly being inside an annular cross-section element made of a material selected from steel, titanium and its alloys. A plate made of a material containing aluminum is located.

  Further, conventionally, for example, the basket of the radioactive substance storage container described in Patent Document 5 is formed in a lattice shape having a plurality of storage compartments by a stainless steel plate containing a neutron absorber, and part or all of the stainless steel plate A heat conduction plate made of a material having a higher heat transfer property than that of the stainless steel plate is disposed on the outside.

  Conventionally, for example, a spent fuel storage basket described in Patent Document 6 is a basket that is provided in a cask and is formed in a lattice shape for storing spent fuel. The boron content per unit volume is smaller than that of the first region, and the second region is located outside the first region on the cross section of the basket.

  Conventionally, for example, the spent fuel storage facility described in Patent Document 7 is used only in a portion where the upper and lower end low burn-up regions of the spent fuel are located in a state where the spent fuel is stored vertically. Equipped with neutron absorber.

JP 2007-212385 A JP 2008-292251 A JP 2002-087991 A JP 2008-134247 A Japanese Patent Laid-Open No. 02-186300 JP 2009-236748 A JP 05-107390 A

  In the radioactive substance storage basket and the radioactive substance storage container, as shown in Patent Document 1 to Patent Document 5 described above, it is hoped to improve the strength of the basket, the neutron absorption performance, and the heat transfer performance. It is rare.

  On the other hand, in Patent Document 6 described above, the lattice in the vicinity of the center on the cross section of the basket is opposite to the spent fuel on both sides, and the number of used spent fuel in the vicinity is large. The neutron flux is said to be large due to neutron irradiation from neutrons and neutron irradiation that occurs from nearby spent fuel and penetrates nearby lattices. For this reason, in the spent fuel storage basket described in Patent Document 6, the second region located outside the first region near the center on the cross section of the basket is more than the first region. The boron content per unit volume is reduced.

  Here, in the fuel assembly applied as the radioactive substance stored in the radioactive substance storage container, a plurality of fuel rods are bundled, and support members are fixed to the upper end part and the lower end part. When storing such a radioactive substance, the upper and lower ends of the fuel assembly have a support member at the upper and lower ends of the radioactive substance, so the neutron flux is relatively small, and there is no fuel between the upper and lower ends. The rod has a relatively large neutron flux.

  Therefore, the neutron flux greatly differs from the cross-sectional direction in terms of the structure of the radioactive material, and it is desired to provide the necessary neutron absorption performance in the vertical direction.

  In Patent Document 7 described above, the neutron absorber is attached only to the portions where the low burnup regions of the upper end portion and the lower end portion of the fuel assembly are located. However, in the spent fuel storage facility shown in Patent Document 7, since the neutron absorber is disposed at a position where the neutron flux is relatively small, the upper end portion and the lower end portion of the fuel assembly having a relatively large neutron flux are arranged. During this time, neutron absorption performance cannot be guaranteed.

  The present invention solves the above-described problems, and provides a radioactive substance storage basket and a radioactive substance storage container capable of obtaining strength and neutron absorption performance and obtaining reasonable neutron absorption performance in the vertical direction of the radioactive substance. The purpose is to provide.

  In order to achieve the above object, the radioactive substance storage basket of the present invention is constructed by stacking a plurality of plate members in the vertical direction and combining the plurality of plate members in a transverse direction perpendicular to the stacking direction, A basket body that defines a plurality of radioactive substance storage portions parallel to the lateral direction and extending in the vertical direction at a predetermined interval; and the basket body includes a rigid plate material, at least a part of which is a strength member, and The neutron absorber plate material which becomes a neutron absorber is overlapped in the horizontal direction, and the neutron absorber plate material is formed with different neutron absorption performance in the vertical direction.

  According to this radioactive substance storage basket, the plate material is configured by laminating a rigid plate material serving as a strength member and a neutron absorber plate material serving as a neutron absorber in the lateral direction, thereby obtaining strength and neutron absorption performance. be able to. In addition, by making the neutron absorption performance of the neutron absorber plate different in the vertical direction, a reasonable neutron absorption performance can be obtained in accordance with the characteristics of the neutron flux in the vertical direction of the radioactive material.

  In the radioactive substance storage basket of the present invention, the neutron absorbing plate material is formed by varying the content of the neutron absorbing material in the vertical direction.

  According to this radioactive material storage basket, strength and neutron absorption performance are obtained, and after obtaining the effect of obtaining reasonable neutron absorption performance in the vertical direction of the radioactive material, the lateral thickness of the neutron absorption plate is reduced. Since the plate thickness in the horizontal direction of the rigid plate material that is equal in the vertical direction and overlaps the neutron absorbing plate material can be equalized in the vertical direction, uniform strength can be obtained in the vertical direction.

  In the radioactive substance storage basket of the present invention, the neutron absorbing plate material is formed with different plate thicknesses in the horizontal direction in the vertical direction.

  According to this radioactive material storage basket, in addition to obtaining strength and neutron absorption performance, and obtaining the effect of obtaining reasonable neutron absorption performance in the vertical direction of the radioactive material, in the part where the neutron flux is small and the strength is to be improved The strength of the neutron absorbing plate can be further improved by reducing the lateral thickness of the neutron absorbing plate and increasing the lateral thickness of the rigid plate.

  In the radioactive substance storage basket of the present invention, the rigid plate material is continuously contacted in the vertical direction.

  According to this radioactive substance storage basket, strength and neutron absorption performance are obtained, and after obtaining the effect of obtaining reasonable neutron absorption performance in the vertical direction of the radioactive substance, the rigid plate material continuous in the vertical direction The strength in the direction can be further improved.

  In the radioactive substance storage basket of the present invention, the rigid plate material and the neutron absorbing plate material are alternately inverted in the horizontal direction in the vertical direction.

  According to this radioactive material storage basket, strength and neutron absorption performance are obtained, and after obtaining the effect of obtaining reasonable neutron absorption performance in the vertical direction of the radioactive material, the rigid plate material and the neutron absorption plate material are Since the rigid plate materials are present on both sides of the plate material stacked in the vertical direction by alternately reversing in the horizontal direction, the rigid plate material exists facing the outer periphery of the radioactive material stored in each radioactive material storage unit. Even when the position of the radioactive substance is shifted due to an impact or the like, the load of the radioactive substance can be received by the rigid plate material, and the radioactive substance can be prevented from being damaged.

  In the radioactive substance storage basket of the present invention, the rigid plate members in the vertical direction are provided so as to be fitted to each other.

  According to this radioactive material storage basket, strength and neutron absorption performance are obtained, and after obtaining the effect of obtaining reasonable neutron absorption performance in the vertical direction of the radioactive material, each fitting in the vertical direction is achieved by mutual fitting. Since the rigid plate members are firmly connected, the strength in the vertical direction and the horizontal direction can be further improved.

  In the radioactive substance storage basket of the present invention, a recess is formed in at least one of the superimposed surfaces of the rigid plate and the neutron absorbing plate, and the penetration penetrates in the lateral direction in which the plate extends. A hole is formed.

  According to this radioactive material storage basket, the strength and neutron absorption performance are obtained, and the effect of obtaining a reasonable neutron absorption performance in the vertical direction of the radioactive material is obtained, and then the through holes receive fast neutrons from the radioactive material. Since it functions as a flux trap for decelerating, the action of attenuating neutrons can be further enhanced.

  In the radioactive substance storage basket of the present invention, the rigid plate material and the neutron absorbing plate material are overlapped by mutual fitting.

  According to this radioactive substance storage basket, after obtaining the strength and neutron absorption performance and obtaining the effect of obtaining a reasonable neutron absorption performance in the vertical direction of the radioactive substance, the rigid plate material and the neutron absorption plate material By overlapping by fitting, the rigid plate material and the neutron absorbing plate material can be overlapped without deviation, and the assemblability can be improved.

  In the radioactive substance storage basket of the present invention, the rigid plate material is made of carbon steel.

  Carbon steel has heat transfer properties superior to stainless steel, and is excellent in workability, and is excellent in strength, toughness, elongation, and the like as compared with an aluminum alloy. Therefore, according to this radioactive substance storage basket, by forming the rigid plate material from carbon steel, it is possible to improve heat transferability and strength and to reduce manufacturing costs during processing. By improving the heat transfer property, the radioactive substance storage unit can be made at a lower temperature, so that the soundness of the radioactive substance stored in the radioactive substance storage unit can be maintained for a longer period of time.

  In the radioactive substance storage basket of the present invention, the rigid plate material made of carbon steel is provided with a surface protective film.

  According to this radioactive substance storage basket, generation of rust in the rigid plate material can be prevented by providing the surface protective film on the rigid plate material made of carbon steel.

  In order to achieve the above object, the radioactive substance storage container according to the present invention includes a cylindrical body having an opening formed on one side and a closing part formed on the other side, and the opening so as to close the opening. It has a cover part which can be attached or detached with respect to a trunk | drum, and the said any one radioactive substance storage basket accommodated in the said trunk | drum.

  According to this radioactive substance storage container, the plate material constituting the basket body of the radioactive substance storage basket is configured by laminating a rigid plate material serving as a strength member and a neutron absorber plate material serving as a neutron absorber in the lateral direction. Thus, strength and neutron absorption performance can be obtained. In addition, by making the neutron absorption performance of the neutron absorber plate different in the vertical direction, a reasonable neutron absorption performance can be obtained in accordance with the characteristics of the neutron flux in the vertical direction of the radioactive material. Therefore, a radioactive substance storage container having a reasonable neutron absorption performance in accordance with the characteristics of the neutron flux in the vertical direction of the radioactive substance can be obtained.

  According to the present invention, strength and neutron absorption performance can be obtained, and reasonable neutron absorption performance can be obtained in the vertical direction of the radioactive substance.

FIG. 1 is a side sectional view of a cask as a radioactive substance storage container according to an embodiment of the present invention. FIG. 2 is a plan sectional view of a cask as a radioactive substance storage container according to an embodiment of the present invention. FIG. 3 is an assembled perspective view of the radioactive substance storage basket according to the embodiment of the present invention. FIG. 4 is an enlarged longitudinal sectional view of the radioactive substance storage basket according to the embodiment of the present invention. FIG. 5 is an enlarged longitudinal sectional view of the radioactive substance storage basket according to the embodiment of the present invention. FIG. 6 is an enlarged longitudinal sectional view of the radioactive substance storage basket according to the embodiment of the present invention. FIG. 7 is an enlarged longitudinal sectional view of the radioactive substance storage basket according to the embodiment of the present invention. FIG. 8 is an enlarged longitudinal sectional view of the radioactive substance storage basket according to the embodiment of the present invention. FIG. 9 is an enlarged longitudinal sectional view of the radioactive substance storage basket according to the embodiment of the present invention. FIG. 10 is an enlarged longitudinal sectional view of the radioactive substance storage basket according to the embodiment of the present invention. FIG. 11 is a chart showing evaluation results according to the examples of the present invention.

  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.

  FIG. 1 is a side 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 part 12, a lid part 13, and a radioactive substance storage 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 radioactive substance storage basket 14. The radioactive substance storage basket 14 has a plurality of cells for individually storing a plurality of radioactive substances (not shown). Details of the configuration of the radioactive substance storage basket 14 will be described later. And the trunk | drum main body 21 has the bottom part 23 couple | bonded by welding to this lower part, and this trunk | drum main body 21 and the bottom part 23 are the forgings 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 12 is a resin (neutron shielding body) 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 shield) 29 is provided. Furthermore, the trunnion 30 is fixed to the trunk | drum 12 in the predetermined position in an outer peripheral part.

  The lid 13 that closes the opening 22 of the trunk body 21 in the trunk 12 includes a primary lid 31 and a secondary lid 32. The primary lid portion 31 has a disk shape made of stainless steel or carbon steel that shields γ rays. The secondary lid portion 32 is also formed of a stainless steel or carbon steel disk, and a resin (neutron shield) 33 is enclosed therein. The primary lid portion 31 and the secondary lid portion 32 are detachably attached to the upper end portion of the trunk body 21 with stainless steel or carbon steel bolts (not shown). In this case, metal gaskets (not shown) are interposed between the primary lid portion 31 and the secondary lid portion 32 and the trunk body 21 to ensure the internal sealing performance. The resin 33 may be provided inside the primary lid 31 or may be provided only on the primary lid 31. In addition, an auxiliary shield 34 enclosing a resin may be provided around the lid portion 13.

  The radioactive substance storage basket 14 will be described in detail. FIG. 3 is an assembled perspective view of the radioactive substance storage basket according to the present embodiment, and FIGS. 4 to 10 are enlarged longitudinal sectional views of the radioactive substance storage basket according to the present embodiment.

  The radioactive substance storage basket 14 of this embodiment has a basket body 41 as shown in FIG. In the basket body 41, radioactive substance storage portions 42 as cells arranged in parallel with each other at a predetermined interval are continuously formed in the vertical direction A. The vertical direction A is a direction along the cylindrical central axis of the trunk portion 12 in the cask 11 and corresponds to the vertical direction A of the trunk body 21.

  Further, as shown in FIG. 2, the radioactive substance storage basket 14 is provided with a support member 45 around the basket body 41. The support member 45 forms the outer shape of the basket body 41, contacts the inner surface of the trunk body 21, and transfers heat from the basket body 41 to the trunk body 21. The support member 45 is made of a material having high heat transfer properties such as carbon steel and aluminum alloy. Further, the support member 45 may be appropriately divided in the vertical direction A or the horizontal direction perpendicular to the vertical direction A for easy manufacture. The support member 45 is coupled to the basket body 41 by bolting, welding, or the like, so that heat transfer with the basket body 41 is good. If bolted, the basket body 41 and the support member 45 can be easily disassembled and assembled at the time of repair.

  As shown in FIG. 3, the basket body 41 is formed by stacking a plurality of plate members 43 in the up-down direction A and combining the plurality of plate members 43 in a transverse direction perpendicular to the stacking direction. Yes. As a result, the basket body 41 defines a plurality of radioactive substance storage portions 42 extending in the vertical direction A parallel to the horizontal direction and at predetermined intervals. Each plate member 43 is provided with a notch 43a at the upper end and the lower end, and is combined so that the notches 43a intersecting each other in the lateral direction are engaged with each other. For this reason, it combines so that each board | plate material 43 which cross | intersects in the horizontal direction may be inserted between each board | plate material 43 stacked up and down. Moreover, the dimension of the up-down direction A is set so that the notch 43a may contact | abut the upper end and lower end of each board | plate material 43 stacked up and down.

  In addition, in FIG. 3, the basket main body 41 has shown the form formed in the grid | lattice form of a rectangular shape by planarly combining the several board | plate material 43 orthogonally in the horizontal direction orthogonal to the stacking direction. For example, the basket main body 41 may be formed in a shape other than a rectangular shape such as a triangular shape by crossing and combining a plurality of plate members 43 in a horizontal direction orthogonal to the stacking direction.

  In addition, the basket body 41 is configured such that the plate member 43 is formed by superimposing a rigid plate member 43A serving as a strength member and a neutron absorbing plate member 43B serving as a neutron absorber in the lateral direction. Since the plate member 43 is assembled by engaging the notch 43a as described above, the superposition of the rigid plate member 43A and the neutron absorbing plate member 43B can be held without being bonded by being inserted into the notch 43a.

  The rigid plate material 43A is made of carbon steel, stainless steel, or aluminum alloy. The neutron absorbing plate 43B has a configuration in which a ceramic layer containing boron carbide as a neutron absorbing material is wrapped with a stainless steel plate or an aluminum alloy plate. Further, the neutron absorbing plate 43B may be made of an aluminum composite material or an aluminum alloy to which boron or a boron compound is added as a neutron absorbing material of aluminum or an aluminum alloy. The neutron absorbing plate material 43B can use gadolinium in addition to boron. Moreover, stainless steel can be used for the neutron absorber plate 43B in addition to aluminum or an aluminum alloy.

  Here, in the fuel assembly applied as a radioactive substance stored in each radioactive substance storage part 42, a plurality of fuel rods are bundled, and support members are fixed to the upper end part and the lower end part. When storing such a radioactive material, the upper and lower ends of the fuel assembly in the vertical direction of the radioactive material have support members at the upper and lower ends of the fuel assembly, so that the neutron flux (the number of neutrons that pass through a certain space in a certain time unit) The neutron flux is relatively large due to the fuel rod between the upper end and the lower end.

  For this reason, in the radioactive substance storage basket 14 of the present embodiment, the neutron absorption plate 43B is formed with different neutron absorption performance in the vertical direction A.

  Specifically, the neutron absorption performance is increased in a portion where the neutron flux is relatively large (for example, the central portion of the radioactive material described above). In addition, in a portion where the neutron flux is relatively small (for example, the upper end portion and the lower end portion of the radioactive material described above), the neutron absorption performance is lowered or is not provided. In order not to have neutron absorption performance, the plate material 43 is only the rigid plate material 43A.

  As described above, the radioactive substance storage basket 14 of the present embodiment is configured by stacking a plurality of plate members 43 in the vertical direction A and combining the plurality of plate members 43 so as to intersect in the lateral direction perpendicular to the stacking direction. The basket body 41 includes a plurality of radioactive substance storage portions 42 that are parallel to the lateral direction and extend in the vertical direction A at predetermined intervals. At least a part of the plate member 43 serves as a strength member. A rigid plate member 43A and a neutron absorber plate 43B serving as a neutron absorber are stacked in the horizontal direction, and the neutron absorber plate 43B is formed with different neutron absorption performance in the vertical direction A.

  According to the radioactive substance storage basket 14, the plate material 43 is configured by superimposing a rigid plate material 43 </ b> A serving as a strength member and a neutron absorption plate material 43 </ b> B serving as a neutron absorber in the lateral direction, thereby increasing strength and neutrons. Absorption performance can be obtained. Moreover, by making the neutron absorption performance of the neutron absorbing plate 43B different in the vertical direction A, a reasonable neutron absorption performance can be obtained in accordance with the characteristics of the neutron flux in the vertical direction A in the radioactive substance.

  In addition, if the plate 43 that forms the basket body 41 is configured by laminating a rigid plate 43A serving as a strength member and a neutron absorber plate 43B serving as a neutron absorber in a lateral direction, the function of obtaining strength and the absorption of neutrons are performed. Function is separated. For this reason, for example, compared with the plate material 43 in which the functions of strength and neutron absorption are combined into one sheet, the plate thickness in the lateral direction of the plate material 43 can be reduced. As a result, it is possible to improve the storage efficiency of the radioactive substance in the basket body 41, and consequently improve the storage efficiency of the radioactive substance in the cask 11.

  In a specific configuration in which the neutron absorption performance of the neutron absorbing plate 43B differs in the vertical direction A, in the case shown in FIG. 4, the lateral thicknesses of the rigid plate 43A and the neutron absorbing plate 43B are made equal in the vertical direction A, The neutron absorber plate 43 </ b> B is formed by varying the content of the neutron absorber in the vertical direction A. In this case, each plate 43 is formed so that the thickness in the horizontal direction is equal in the vertical direction A.

  If comprised in this way, while obtaining intensity | strength and neutron absorption performance, and obtaining the effect of obtaining rational neutron absorption performance in the up-down direction A of a radioactive substance, the plate | board thickness of the horizontal direction of the neutron absorption board | plate material 43B is made into the up-down direction. Since the plate thickness in the lateral direction of the rigid plate 43A overlapping with the neutron absorbing plate 43B can be made equal in the vertical direction A, a uniform strength can be obtained in the vertical direction A.

  5 and FIG. 6, the neutron absorbing plate 43B is formed with the plate thickness in the horizontal direction different in the vertical direction A. In this case, the neutron absorbing plate 43B is formed to have the same content of neutron absorbing material in the vertical direction A, and each plate 43 is formed to have the same horizontal thickness in the vertical direction A. In the case shown in FIG. 6, the neutron absorbing plate material 43B is not provided at the upper end portion and the lower end portion, and only the rigid plate material 43A is used.

  If comprised in this way, while obtaining intensity | strength and neutron absorption performance, and obtaining the effect of obtaining rational neutron absorption performance in the up-down direction A of a radioactive substance, the part which wants to improve intensity | strength with small neutron flux, for example, the above-mentioned In the upper end portion and the lower end portion of the radioactive material, the thickness of the neutron absorbing plate 43B in the lateral direction can be reduced, and the thickness of the rigid plate 43A in the lateral direction can be increased to further improve the strength.

  4 to 10, the rigid plate member 43A is continuously in contact with the vertical direction A.

  With this configuration, the strength and neutron absorption performance can be obtained, and after obtaining the effect of obtaining a reasonable neutron absorption performance in the vertical direction A of the radioactive substance, the rigid plate material 43A continuous in the vertical direction A can be used in the vertical direction. The strength of A can be further improved.

  Further, in the case shown in FIG. 7, the rigid plate material 43 </ b> A and the neutron absorbing plate material 43 </ b> B are alternately inverted in the horizontal direction in the vertical direction A. That is, the plate material 43 obtained by superimposing the rigid plate material 43A and the neutron absorbing plate material 43B in the horizontal direction is disposed so as to be reversed in the horizontal direction.

  With this configuration, the strength and neutron absorption performance are obtained and the effect of obtaining a reasonable neutron absorption performance in the vertical direction A of the radioactive substance is obtained, and then the rigid plate material 43A and the neutron absorption plate material 43B are moved in the vertical direction A. Since the rigid plate members 43A are present on both surfaces of the plate member 43 stacked in the vertical direction A by alternately reversing in the horizontal direction, the rigid plate member faces the outer periphery of the radioactive substance stored in each radioactive substance storage unit 42. Since 43A exists, even when the position of the radioactive substance is shifted due to impact or the like, the load of the radioactive substance can be received by the rigid plate member 43A, and the radioactive substance can be prevented from being damaged.

  Further, in the case shown in FIG. 8, the rigid plate material 43 </ b> A is provided in the up-down direction A so as to be fitted to each other by the convex portion 43 </ b> Aa and the concave portion 43 </ b> Ab. In FIG. 8, the plate member 43 has the same configuration except for the upper end portion and the lower end portion, and is inverted in the horizontal direction. However, in the form shown in FIGS. 4 to 7, 9 and 10, The plate member 43A may be provided so as to be fitted to each other in the vertical direction A by the convex portion 43Aa and the concave portion 43Ab.

  With this configuration, the strength and neutron absorption performance are obtained, and after obtaining the effect of obtaining a reasonable neutron absorption performance in the vertical direction A of the radioactive substance, each fitting portion 43Aa and the depression portion 43Ab are fitted to each other. Since the rigid plate 43A is firmly connected, the strength in the vertical direction A and the horizontal direction can be further improved.

  In addition, in the case shown in FIG. 9, recesses 43Ac and 43Bc are formed on the overlapping surface of the rigid plate material 43A and the neutron absorbing plate material 43B, and the through-hole penetrating in the lateral direction in which the plate material 43 extends by the recesses 43Ac and 43Bc. 43C is formed. Note that the through hole 43C may be formed by a recess 43Ac or a recess 43Bc formed on at least one of the surfaces of the rigid plate 43A and the neutron absorbing plate 43B that are overlapped. A plurality of through holes 43 </ b> C may be formed in one plate member 43.

  If comprised in this way, while obtaining the effect which acquires intensity | strength and neutron absorption performance and the reasonable neutron absorption performance in the up-down direction A of a radioactive substance, the through-hole 43C decelerates the fast neutron from a radioactive substance. Therefore, the function of attenuating neutrons can be further enhanced.

  Further, in the case shown in FIG. 10, the mutual surfaces obtained by superposing the rigid plate material 43A and the neutron absorbing plate material 43B are overlapped by fitting the convex portion 43Ad and the concave portion 43Bd. In FIG. 10, the convex portion 43Ad is provided in the rigid plate material 43A and the concave portion 43Bd is provided in the neutron absorbing plate material 43B. However, the present invention is not limited to this, but the concave portion is provided in the rigid plate material 43A. The neutron absorbing plate 43B may be provided with a convex portion. Further, although not shown in the drawing, the rigid plate material 43A and the neutron absorbing plate material 43B may be provided with convex portions and concave portions, and the convex portions and the concave portions may be fitted and overlapped.

  If comprised in this way, while obtaining intensity | strength and neutron absorption performance, and obtaining the effect of obtaining rational neutron absorption performance in the up-down direction A of a radioactive substance, the rigid board | plate material 43A and the neutron absorption board material 43B mutually fit. By superimposing, the rigid plate member 43A and the neutron absorbing plate member 43B can be overlapped without deviation and the assemblability can be improved.

  Further, in the radioactive substance storage basket 14 of the present embodiment, the rigid plate member 43A is preferably made of carbon steel (for example, SGV480 or SGV650).

  Carbon steel has heat transfer properties superior to stainless steel, has heat removal performance, is excellent in workability, and is excellent in strength, toughness, elongation, and the like as compared with an aluminum alloy. Therefore, by forming the rigid plate material 43A from carbon steel, it is possible to improve heat transferability and strength and reduce manufacturing costs during processing. By improving the heat transfer property, the radioactive substance storage part 42 can be cooled to a lower temperature, so that the soundness of the radioactive substance stored in the radioactive substance storage part 42 can be maintained for a longer period.

  In particular, since carbon steel has excellent heat transfer properties and strength, it can be designed with a plate thickness required for strength. On the other hand, the basket main body 41 made of stainless steel has a thickness greater than that necessary for strength in order to guarantee heat transferability in addition to strength, and the storage efficiency of radioactive materials is reduced. Therefore, by forming the rigid plate material 43A from carbon steel, it is possible to improve the storage efficiency of the radioactive substance in the basket body 41, and thus improve the storage efficiency of the radioactive substance in the cask 11.

  Moreover, carbon steel is easier to weld than stainless steel. In the basket body 41 described above, the plate member 43 is assembled by the notch 43a. However, there is a possibility that the heat transferability of the notch 43a portion may be restricted at the intersecting portion, but by joining by welding without using the notch 43a, Restrictions can be removed, and heat transferability and strength can be further improved.

  Moreover, in the radioactive substance storage basket 14 of this embodiment, it is preferable that the hard plate 43A made of carbon steel is provided with a surface protective film. The surface protective film can be applied by plating (nickel plating), thermal spraying, passivation treatment, vapor deposition treatment, plasma treatment, coating, or the like.

  Therefore, by providing a surface protective film on the rigid plate material 43A made of carbon steel, it is possible to prevent rust from occurring on the rigid plate material 43A.

  Further, the radioactive substance storage container (cask 11) of the present embodiment has a cylindrical body portion 12 having an opening 22 formed on one side and a closed portion (bottom 23) formed on the other side, and the opening 22 formed therein. The lid 13 is detachable from the body 12 so as to be closed, and the above-described radioactive substance storage basket 14 accommodated in the body 12.

  According to the cask 11, the plate member 43 constituting the basket body 41 of the radioactive substance storage basket 14 is obtained by superimposing the rigid plate member 43A serving as a strength member and the neutron absorbing plate member 43B serving as a neutron absorber in the lateral direction. By being configured, strength and neutron absorption performance can be obtained. Moreover, by making the neutron absorption performance of the neutron absorbing plate 43B different in the vertical direction A, a reasonable neutron absorption performance can be obtained in accordance with the characteristics of the neutron flux in the vertical direction A in the radioactive substance. Therefore, the cask 11 having a reasonable neutron absorption performance can be obtained in accordance with the characteristics of the neutron flux in the vertical direction A in the radioactive material.

  FIG. 11 is a chart showing evaluation results according to the examples of the present invention. In this example, for basket bodies with different conditions, in Comparative Example 1, Comparative Example 2, Comparative Example 3 and Examples, subcritical performance, heat removal performance, structural strength performance, anticorrosion performance, structure, production and manufacturing costs are related. Evaluation was performed.

  In Comparative Example 1, a boron-added aluminum alloy plate (referred to as a boron / aluminum plate) was used as a structural material, and a single plate material, a boron / aluminum plate, was assembled in a lattice shape as a structure. (See FIG. 3). In Comparative Example 1, a member that ensures subcritical performance, heat removal performance, structural strength performance, and anticorrosion performance is a boron aluminum plate.

  In Comparative Example 2, a boron-added stainless alloy plate (referred to as a boron / stainless steel plate) and a copper plate were used as the structural material, and as the structure, two types of plate materials, a boron / stainless steel plate and a copper plate, were used. They are assembled in a lattice shape by overlapping (see FIG. 3). In Comparative Example 2, the member that ensures the subcritical performance and the structural strength performance is the boron / stainless steel plate, and the member that secures the heat removal performance and the anticorrosion performance is the boron / stainless steel plate and the copper plate.

  In Comparative Example 3, a forged aluminum alloy block (referred to as a forged aluminum block) and a boron-added aluminum alloy sheet-like thin plate (referred to as boron / aluminum thin plate) were used as the structural material. Boron / aluminum sheet is pasted on the surface of the block. Although the forged aluminum block is not clearly shown in the drawings, for example, the basket shown in FIGS. 1 and 2 is forged as a lump and processed in detail. In Comparative Example 3, a member that ensures subcritical performance is a boron aluminum thin plate, and a member that secures heat removal performance, structural strength performance, and anticorrosion performance is a forged aluminum block.

  In the example which is the radioactive substance storage basket described in the above-described embodiment, as a structural material, carbon steel and a sheet-like thin plate made of boron-added aluminum alloy (referred to as boron-aluminum thin plate) is used. As a structure, carbon steel, which is two kinds of plate materials, and a boron / aluminum thin plate are superposed and assembled in a lattice shape (see FIG. 3). In this example, the member that ensures subcritical performance is boron / aluminum thin plate, the member that secures heat removal performance is carbon steel and boron / aluminum thin plate, the member that secures structural strength performance is carbon steel, A member for ensuring performance is a surface protective film (here, nickel plating) applied to the surface of carbon steel.

  As shown in FIG. 11, in Comparative Example 1, all performances are made to function with a boron aluminum plate. For this reason, in Comparative Example 1, the evaluation of the heat removal performance is “excellent”, the evaluation of the anticorrosion performance is “good”, and the evaluation of the subcritical performance and the structural strength performance is “good”. Further, since Comparative Example 1 is a single plate material assembled in a lattice shape, the structure is simple and the evaluation is “excellent”. However, in Comparative Example 1, since boron / aluminum is manufactured as a structural strength member, the manufacturing method is very special, and the productivity and yield are poor. Moreover, since the hardness is high, the machinability is poor. For this reason, evaluation of production and manufacturing costs is “impossible”.

  In Comparative Example 2, the subcritical performance and the structural strength performance are made to function with the boron / stainless steel plate, and the heat removal performance and the anticorrosion performance are made to work with the boron / stainless steel plate and the copper plate. For this reason, in Comparative Example 2, the evaluation of the structural strength performance and the anticorrosion performance is “good”, and the evaluation of the subcritical performance is “good”, but the heat removal performance is evaluated because stainless steel has poor heat transfer performance. “Not possible”. In addition, since Comparative Example 2 is an assembly in which two kinds of plate materials are stacked and assembled in a lattice shape, the structure is relatively simple and the evaluation is “good”. Further, in Comparative Example 2, since boron / stainless steel is manufactured as a structural strength member, the manufacturing method is extremely special, and the productivity and yield are poor. Moreover, since the hardness is high, the machinability is poor. For this reason, the evaluation of the manufacturing cost is “good” compared to the comparative example 1, but the evaluation of the production is “impossible”.

  Moreover, the comparative example 3 makes subcritical performance function with a boron aluminum thin plate, and makes heat removal performance, structural strength performance, and anticorrosion performance function with a forged aluminum block. For this reason, in Comparative Example 3, the evaluation of the heat removal performance is “excellent”, the evaluation of the subcritical performance and the anticorrosion performance is “good”, and the evaluation of the structural strength performance is “good”. However, in Comparative Example 3, since it is necessary to process the forged aluminum block into an extremely complicated shape, the evaluation of the structure is “impossible”. Furthermore, in Comparative Example 3, it is easy to manufacture a boron / aluminum thin plate, but it is necessary to process the forged aluminum block into an extremely complicated shape, and high precision and great machining are required. Is “impossible”.

  On the other hand, in the examples, the subcritical performance is made to function with boron / aluminum sheet, the heat removal performance is made to function with carbon steel and boron / aluminum sheet, the structural strength performance is made to function with carbon steel, and the corrosion resistance is made to be The surface protection film applied to the For this reason, the evaluation of structural strength is “excellent”, and the evaluation of subcritical performance, heat removal performance and anticorrosion performance is “good”. Moreover, since the example is an assembly in which two kinds of plate materials are stacked and assembled in a lattice shape, the structure is relatively simple and the evaluation is “good”. Further, in the examples, the production of the boron / aluminum sheet is easy, and the carbon steel is easy to machine, so that the evaluation of the production and production cost is “excellent”.

  As described above, in Comparative Examples 1 to 3, although there are items of “good” or higher among subcritical performance, heat removal performance, structural strength performance, anticorrosion performance, structure, production, and manufacturing cost, ”Is included. On the other hand, in the examples, all of subcritical performance, heat removal performance, structural strength performance, anticorrosion performance, structure, production, and manufacturing cost are evaluated as “good” or higher, and it can be seen that they are excellent.

11 Cask (radioactive substance storage container)
12 trunk 13 lid 14 radioactive substance storage basket 22 opening 23 bottom (blocking)
41 Basket body 42 Radioactive material storage part 43 Plate material 43A Rigid plate material 43Aa Protrusion part 43Ab Concave part 43Ac Concave part 43Ad Convex part 43B Neutron absorbing plate material 43Bc Concave part 43Bd Concave part 43C Through hole A Vertical direction

Claims (11)

A plurality of radioactive materials extending in the vertical direction parallel to the horizontal direction and at a predetermined interval while the plurality of plate materials are stacked upright in the vertical direction and combined with each other in the horizontal direction perpendicular to the stacking direction. Having a basket body that partitions the storage section;
The basket main body is configured such that at least a part of the plate material is formed by superimposing a rigid plate material serving as a strength member and a neutron absorber plate material serving as a neutron absorber in the lateral direction, and the neutron absorption plate material is disposed in the vertical direction. formed with different neutron absorbing performance by varying the thickness of the plate thickness, the radioactive substance storage basket, characterized in that the thickness of the lateral formed by each of said plate members stacked in the vertical direction are the same. A plurality of radioactive materials extending in the vertical direction parallel to the horizontal direction and at a predetermined interval while the plurality of plate materials are stacked upright in the vertical direction and combined with each other in the horizontal direction perpendicular to the stacking direction. Having a basket body that partitions the storage section;
The basket body is configured such that at least a part of the plate material is formed by laminating a rigid plate material serving as a strength member and a neutron absorber plate material serving as a neutron absorber in a lateral direction, and the neutron absorption plate material is neutron absorbing performance in the vertical direction. the varied formed,
The radioactive substance storage basket, wherein the rigid plate material and the neutron absorbing plate material are alternately inverted in the horizontal direction in the vertical direction . The radioactive substance storage basket according to claim 2 , wherein the neutron absorbing plate is formed by varying the content of the neutron absorbing material in the vertical direction. The radioactive substance storage basket according to claim 2 , wherein the neutron absorbing plate material is formed with different plate thicknesses in the horizontal direction in the vertical direction. The radioactive substance storage basket according to any one of claims 1 to 4 , wherein the rigid plate material is continuously contacted in the vertical direction.   The radioactive material storage basket according to any one of claims 1 to 5, wherein the rigid plate members in the vertical direction are provided to be fitted to each other.   The concave portion is formed in at least one of the overlapping surfaces of the rigid plate material and the neutron absorbing plate material, and the through hole penetrating in the lateral direction in which the plate material extends is formed by the concave portion. The radioactive substance storage basket according to any one of 1 to 6.   The radioactive material storage basket according to any one of claims 1 to 7, wherein the rigid plate material and the neutron absorbing plate material are overlapped by mutual fitting.   The radioactive material storage basket according to claim 1, wherein the rigid plate material is made of carbon steel.   The radioactive material storage basket according to claim 9, wherein the rigid plate material made of carbon steel is provided with a surface protective film. A barrel part having an opening formed on one side and a closed part formed on the other to form a cylinder;
A lid that can be attached to and detached from the trunk so as to close the opening;
The radioactive substance storage basket according to any one of claims 1 to 10, which is accommodated in the trunk portion,
The radioactive substance storage container characterized by having.

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