JP5787813B2 - Radioactive material containment vessel - Google Patents

Description

  The present invention relates to a radioactive substance storage container for storing a fuel assembly containing a radioactive substance.

  As this type of radioactive substance storage container, there are a cask used for transportation and storage of a fuel assembly used for nuclear power generation, and a rack for storing the fuel assembly in a fuel pool. In these casks and racks, lattice-like cells are formed by a collection of square pipes and the like, and a fuel assembly is stored in the cells. In order to maintain the subcriticality of the fuel in this stored state, a cask is known in which a plate-like neutron absorber is fixed to the outer surface of a square pipe (see, for example, Patent Document 1).

  In the cask described in Patent Document 1, a groove is formed in the longitudinal direction on the outer surface of the square pipe, and a neutron absorber is fitted into the groove, and the neutron absorber is provided integrally with the square pipe.

JP 2008-96149 A

  However, in the cask described in the above-mentioned Patent Document 1, since the groove portion needs to be processed in the longitudinal direction on the outer surface of the square pipe, the processing cost increases.

  The objective of this invention is providing the radioactive substance storage container of the simple structure which does not require the process of a groove part.

  A radioactive substance storage container according to an aspect of the present invention is a radioactive substance storage container that stores and stores a plurality of fuel assemblies containing a radioactive substance, and the storage unit and the storage unit are stored with a plurality of fuel assemblies. A cell structure partitioned into a plurality of accommodating spaces, a flat neutron absorber disposed facing the inner surface of the cell structure, and a neutron disposed in the accommodating space facing the neutron absorber And a holding member that holds the absorbent and forms a storage portion of the fuel assembly.

  According to this configuration, since it is not necessary to fix the neutron absorber to the cell structure, the cell structure can be easily processed, and an increase in processing cost can be suppressed.

  In the radioactive substance storage container according to another aspect of the present invention, the accommodation space has a rectangular parallelepiped shape, the holding member extends in the insertion direction of the fuel assembly, and the cross section has an L shape.

  According to this configuration, the holding member can be easily formed by bending a flat plate or the like.

  In the radioactive substance storage container according to another aspect of the present invention, the accommodation space has a rectangular parallelepiped shape, the holding member extends in the insertion direction of the fuel assembly, and has a rectangular frame shape in cross section.

  According to this configuration, the frame portion having a predetermined shape can be accurately formed in the accommodation space, and the neutron absorber and the fuel assembly can be easily inserted into the accommodation space.

  In the radioactive substance storage container according to another aspect of the present invention, the cell structure is made of a constituent material that does not include a material having neutron absorption performance.

  According to this configuration, a high-strength material can be used as the cell structure, and the cell structure can be easily thinned.

  In the radioactive substance storage container according to another aspect of the present invention, the holding member is made of a constituent material that does not include a material having neutron absorption performance.

  According to this configuration, the workability of the thin member is improved, and a thin member having a predetermined shape can be easily obtained.

  In the radioactive substance storage container according to another aspect of the present invention, the holding member has a position restricting portion that restricts the position of the holding member in the accommodation space.

  According to this configuration, since the position of the holding member is constrained, the installation space for the neutron absorber can be easily secured.

  In the radioactive substance storage container according to another aspect of the present invention, the holding member has an inlet portion for inserting the fuel assembly into the accommodation space at the end portion, and the inlet portion is an opening on the insertion side of the fuel assembly. It is provided to increase the area.

  According to this configuration, since the inlet area increases, the fuel assembly can be easily inserted into the accommodation space without being caught.

  In the radioactive substance storage container according to another aspect of the present invention, the cell structure has an outer partition wall portion arranged at the outermost part and an inner partition wall portion arranged inside the outer partition wall portion, and the neutron absorber is The inner partition wall faces the inner surface and is not disposed on the outer partition wall inner surface.

  According to this configuration, since the neutron absorber is disposed only at a necessary location, the installation space for the fuel assembly can be expanded.

  ADVANTAGE OF THE INVENTION According to this invention, the raise of processing cost can be suppressed and the radioactive substance storage container provided with the neutron absorber can be comprised.

FIG. 1 is a longitudinal sectional view showing a schematic configuration of a radioactive substance storage container according to the first embodiment of the present invention. FIG. 2 is a cross-sectional view of FIG. 1 taken along the line II-II. FIG. 3 is an enlarged view of one accommodation space in FIG. FIG. 4 is a diagram showing a modification of FIG. FIG. 5 is a diagram showing another modification of FIG. FIG. 6 is a diagram showing a portion corresponding to FIG. 3 in the radioactive substance storage according to the second embodiment of the present invention. FIG. 7 is a diagram showing a modification of the present invention. FIG. 8 is a diagram showing another modification of the present invention.

(First embodiment)
Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a longitudinal sectional view showing a schematic configuration of a radioactive substance storage container according to the first embodiment, and FIG. 2 is a sectional view taken along line II-II in FIG. Here, as the radioactive substance storage container, a cask 100 that stores an assembly (fuel assembly) of recycled fuel is illustrated.

  In the following, for convenience of explanation, the lid 2 of the cask 100 is defined as the upper side, the bottom 1b is defined as the lower side, and the vertical direction is defined as shown in FIG. 1, and the configuration of each part will be described according to this definition. This direction changes according to the usage state of the cask 100, and the configuration of the cask 100 is not limited to the direction of FIG. FIG. 1 is a cross-sectional view of the cask 100 taken along the center line (axis line) of the cask 100 extending in the vertical direction. The fuel assembly 101 has a rectangular parallelepiped shape, and the vertical direction coincides with the direction in which the fuel assembly 101 is inserted into the cask 100. The rectangular parallelepiped shape in this case includes not only a pure rectangular parallelepiped shape but also a shape substantially equivalent to the rectangular parallelepiped shape.

  As shown in FIGS. 1 and 2, the cask 100 includes a trunk body 1, a lid body 2, a basket 10, a heat transfer plate 3, an outer cylinder 4, and a neutron shield 5. In addition, illustration of the basket 10 is abbreviate | omitted in FIG. 1, and illustration of the detailed shape of the basket 10 is abbreviate | omitted in FIG.

  The trunk body 1 has a bottomed cylindrical shape with a closed bottom surface, and an opening 1a is provided on the upper end surface. A hollow cylindrical cavity 6 for accommodating a plurality of fuel assemblies 101 is formed inside the trunk body 1. The cavity 6 has a vertical length corresponding to the shape of the fuel assembly 101. The trunk body 1 is made of a material such as stainless steel or carbon steel, and has a thickness that can block γ rays emitted from the fuel assembly 101. As shown in FIG. 1, the bottom part 1b and the side part 1c of the trunk body 1 may be integrally formed, but after these are formed separately, they may be integrated by welding or the like.

  The lid 2 has a double structure having a primary lid 2a that closes the opening 1a of the trunk body 1 and a secondary lid 2b that covers the upper side of the primary lid 2a. The primary lid 2a and the secondary lid 2b are each made of a material such as stainless steel or carbon steel that has a disk shape as a whole and can shield γ rays. In addition, the disk shape in this case includes not only a pure disk shape but also a shape substantially equivalent to the disk shape. The primary lid 2a and the secondary lid 2b are detachably attached to the upper end surface of the trunk body 1 with bolts or the like. Although illustration is omitted, metal gaskets are interposed in the attachment portions of the primary lid 2a and the secondary lid 2b, respectively, and the spaces in the cavity 6 and between the primary lid 2a and the secondary lid 2b are airtight, respectively. It is sealed.

  The basket 10 is configured by binding a plurality of square pipes 11 corresponding to the outer shape of the fuel assembly 101 so that the side surfaces thereof are in contact with each other. Is formed. That is, the basket 10 forms a cell structure by the plurality of square pipes 11. Each square pipe 11 extends in the vertical direction and forms an elongated rectangular parallelepiped-shaped accommodation space 12 in which the fuel assembly 101 is accommodated. The basket 10 is positioned in the trunk body 1 by setting the inner peripheral surface of the cavity 6 to a shape corresponding to the outer peripheral shape of the basket 10. Note that the peripheral surface of the cavity 6 may be a simple cylinder, and a spacer having excellent heat transfer performance may be disposed in the gap between the cavity 6 and the basket 10. A neutron absorber that absorbs neutrons emitted from the fuel assembly 101 is provided in the basket 10, which will be described later.

  The heat transfer plate 3 is a plurality of plate-like members, and one end in the longitudinal direction thereof is radially attached to the outer peripheral surface of the trunk body 1. The heat transfer plate 3 is made of the same kind of material as the trunk body 1 or a material having good thermal conductivity such as a trunk or aluminum. The heat transfer plate 3 transfers heat from the trunk body 1 to the outer cylinder 4.

  The outer cylinder 4 is a cylindrical body having a constant thickness arranged on the outer peripheral portion of the cask 100. The other end portions of the plurality of heat transfer plates 3 are attached to the inner peripheral surface of the outer cylinder 4, and the heat transferred to the outer cylinder 4 through the heat transfer plates 3 enters the atmosphere from the outer peripheral surface of the outer cylinder 4. Released. A cylindrical space between the outer peripheral surface of the trunk body 1 and the inner peripheral surface of the outer cylinder 4 is partitioned into a plurality of divided spaces 7 in the circumferential direction by the heat transfer plate 3.

  The neutron shield 5 is filled in each divided space 7 partitioned by the heat transfer plate 3 and is disposed so as to surround the outer periphery of the trunk body 1. The neutron shield 5 is made of a resin containing a predetermined amount of hydrogen and added with boron or a boron compound. The neutron shield 5 shields neutrons emitted from the fuel assembly 101 and suppresses leakage of neutrons to the outside of the cask 100.

  The cask 100 configured as described above is required to have a function (neutron absorption function) of absorbing a neutron emitted from the fuel assembly 101 and maintaining a subcritical state. In order to satisfy this requirement, for example, it is conceivable to form the square pipe 11 as the cell structure by using a steel material such as stainless steel to which boron or a boron compound is added, aluminum, an aluminum alloy, or the like. However, since the boron-containing material has higher hardness than the non-boron-containing material, when the cell structure is constituted by the boron-containing material, the workability is remarkably inferior and the processing cost is increased.

  On the other hand, as another method, the square pipe 11 as the cell structure is made of a boron-free material, and the neutron absorber is fixed to the outer surface of each square pipe 11 so that the neutron absorber and the cell structure are integrated. It can be considered to be provided in However, in this case, it is necessary to perform processing (for example, groove processing) for fixing the neutron absorbing material to the cell structure, and the shape of the cell structure becomes complicated and processing cost increases. In particular, since the fuel assembly is long, a long neutron absorber is required. For this reason, in order to attach the long neutron absorber to the cell structure integrally, it is necessary to increase the processing accuracy of the groove processing, which tends to increase the processing cost.

  Therefore, in this embodiment, in order to suppress an increase in processing cost and to arrange the neutron absorber in the basket 10 with a simple configuration, the following configuration is provided.

  FIG. 3 is an enlarged view of the accommodation space 12 shown in FIG. FIG. 3 shows a state in which the spent fuel assembly 101 is loaded in the accommodation space 12 in the basket 10. As shown in FIG. 3, a pair of thin plate-shaped holding members 20 whose horizontal cross section is L-shaped are disposed in the accommodating space 12 so as to surround the fuel assembly 101. Further, neutron absorbers 15 are respectively disposed between the holding member 20 and each inner side surface of the square pipe 11. In addition, the L-shape in this case includes not only a pure L-shape but also a shape substantially equivalent to the L-shape.

  The neutron absorber 15 has a rectangular flat plate shape as a whole, and has a predetermined thickness t1 (for example, about 1 mm) throughout. The rectangle in this case includes not only a pure rectangle but also a shape substantially equivalent to the rectangle. The neutron absorber 15 has a function of absorbing neutrons emitted from the fuel assembly 101. The vertical length of the neutron absorber 15 is substantially equal to the vertical length of the fuel assembly 101, and the cross-sectional shape is constant over the entire vertical length. The neutron absorber 15 absorbs neutrons emitted from the fuel assembly 101 disposed in the adjacent accommodation space 12a.

  In FIG. 3, when the four inner side surfaces of the square pipe 11 are a first side surface 111, a second side surface 112, a third side surface 113 and a fourth side surface 114, the neutron absorber 15 has a first side surface 111 to a fourth side surface. 114 facing each other. Thereby, the entire inner surface of the square pipe 11 is almost covered with the neutron absorber 15.

  More precisely, the width W1 of the neutron absorber 15 (referred to as the first neutron absorber 151) facing the first side surface 111 and the third side surface 113 is based on the distance Wa from the second side surface 112 to the fourth side surface 114. The first neutron absorber 151 is slightly shorter (for example, shorter by about 1 mm), and is disposed with a gap from the second side surface 112 and the fourth side surface 114 of the square pipe 11. On the other hand, the width W2 of the neutron absorber 15 (referred to as the second neutron absorber 152) facing the second side surface 112 and the fourth side surface 114 is determined from the distance Wb from the first side surface 111 to the third side surface 113 from the plate thickness t1. Is slightly shorter (for example, about 1 mm shorter) than the value obtained by subtracting 2 times (Wb−2 × t1), and the second neutron absorber 152 is disposed with a gap from the inner surface of the first neutron absorber 151. .

  In addition, when the accommodation space 12 has a square cross section, that is, when the distance Wa from the second side surface 112 to the fourth side surface 114 and the distance Wb from the first side surface 111 to the third side surface 113 are equal to each other, it is shown in FIG. Thus, the width W3 of the neutron absorber 15 may be formed slightly shorter (for example, shorter by about 1 mm) than the value obtained by subtracting the thickness t1 of the neutron absorber 15 from the distance Wc (= Wa = Wb). In this case, each neutron absorber 15 is arranged so that one end surface of the neutron absorber 15 faces the first side surface 111 to the fourth side surface 114 and the other end surface faces the inner surface of the adjacent neutron absorber 15. That's fine. Thereby, all the neutron absorbers 15 can have the same shape, which contributes to cost reduction.

  Note that the gaps at both end faces in the width direction of the neutron absorber 15 are determined in consideration of the neutron absorption function exhibited by the neutron absorber 15, and the gap may be made smaller or larger, depending on the case. The neutron absorber 15 may be arranged with 0 set to 0.

  The neutron absorber 15 is, for example, a boron-containing material configured by adding boron to aluminum powder, and the boron content is, for example, about 30% by weight. On the other hand, if the square pipe 11 is made of a boron-containing material, the boron content of the square pipe 11 is generally less than 10% (for example, about 7%) in consideration of workability. In this respect, in this embodiment, since the neutron absorber 15 is configured separately from the square pipe 11, the neutron absorber 15 having a high boron content can be used, and neutrons released from the fuel assembly 101 can be used. It can be absorbed efficiently.

  As shown in FIG. 3, the holding member 20 is formed, for example, by bending a thin plate having a predetermined thickness t <b> 2 at a right angle, and has support portions 22 and 23 on both sides of the bent portion 21. The right angle includes not only a pure right angle but also a shape substantially equivalent to a right angle. The vertical length of the holding member 20 is substantially equal to the vertical length of the fuel assembly 101, and its cross-sectional shape is constant over the entire vertical length. The pair of holding members 20 in the accommodation space 12 have the same shape.

  One holding member 20 (referred to as a first holding member 201) is arranged with a pair of support portions 22 and 23 facing the neutron absorbers 15 on the first side face 111 side and the fourth side face 114 side, respectively. The other holding member (referred to as the second holding member 202) is arranged with the pair of support portions 23 and 22 facing the neutron absorber 15 on the second side surface 112 side and the third side surface 113 side, respectively. The end portion of the support portion 22 of the first holding member 201 is in contact with or close to the end portion of the support portion 23 of the second holding member 202, and the end portion of the support portion 23 of the first holding member 201 is the second holding portion. It is in contact with or close to the end of the support portion 22 of the member 202. Thereby, a rectangular frame portion 25 is formed in the accommodating space 12, and the neutron absorber 15 is disposed in the outer space 13 of the frame portion 25 in the accommodating space 12. The rectangle in this case includes not only a pure rectangle but also a shape substantially equivalent to the rectangle.

  More precisely, the width W4 of the support portion 22 is a value obtained by subtracting twice the plate thickness t1 of the neutron absorber 15 and the plate thickness t2 of the holding member 20 from the distance Wa from the second side surface 112 to the fourth side surface 114. Slightly shorter than (Wb-2 × t1-t2) (for example, about 1 mm shorter). The width W5 of the support portion 23 is a value obtained by subtracting twice the plate thickness t1 of the neutron absorber 15 and the plate thickness t2 of the holding member 20 from the distance Wb from the first side surface 111 to the third side surface 113 (Wa−). 2 × t1−t2) slightly shorter (for example, about 1 mm shorter). As a result, the position of the neutron absorber 15 is regulated, and the neutron absorber 15 is held in a posture (referred to as an opposite posture) that is close to the inner surface of the square pipe 11 and parallel to the inner surface of the square pipe 11. Can do. In addition, the parallel in this case includes not only a pure parallel state but also a state substantially equivalent to the parallel state.

  In the state of FIG. 3, the holding member 20 is not fixed to a structural component (such as the square pipe 11) of the cask 100, and other components (the neutron absorber 15 and the other holding member 20) in the accommodation space 12. It can move in the accommodation space 12 until it comes into contact. The neutron absorber 15 is also not fixed to the square pipe 11 or the like, and maintains the facing posture until it comes into contact with other components (the holding member 20, the square pipe 11, or other neutron absorber 15) in the accommodation space 12. However, it can move in the outer space 13.

  The gaps on both sides in the thickness direction of the neutron absorber 15 are determined in consideration of the installation procedure of the neutron absorber 15 and the holding member 20 in the accommodation space 12, ease of installation, and the like. May be made smaller or larger, and the neutron absorbing material may be arranged with the gap set to 0 in some cases. In addition, the lengths W4 and W5 of the support portions 22 and 23 can be set to values different from each other. However, when the accommodation space 12 has a square shape as shown in FIG. The lengths W4 and W5 may be equal to each other. The square shape in this case includes not only a pure square shape but also a shape substantially equivalent to the square shape.

  A storage section 26 having a rectangular cross section is formed inside the frame section 25 formed by the pair of holding members 20, and the fuel assembly 101 is stored in the storage section 26. The rectangular cross section in this case includes not only a pure rectangular cross section but also a cross section substantially equivalent to a rectangle. The width direction dimension of the storage portion 26 is larger than the width of the fuel assembly 101 by a predetermined length (for example, about 1 to 2 mm) in order to facilitate the insertion of the fuel assembly 101 into the storage portion 26.

  The holding member 20 is made of a material having a predetermined thickness that does not include boron, such as a steel material (for example, stainless steel), aluminum, or an aluminum alloy. The cask 100 needs to have sufficient structural strength when dropped horizontally, that is, when dropped in a state where the vertical direction is horizontal, but the holding member 20 has a single fuel assembly 101 when dropped horizontally. The structural strength required at the time of horizontal drop is mainly secured by the square pipe 11. For this reason, the thickness t2 of the holding member 20 is sufficient to be able to hold the neutron absorber 15 in the facing posture (for example, about 0.5 mm).

  In this embodiment, since the neutron absorber 15 having a neutron absorption function is provided separately from the square pipe 11, the square pipe 11 itself does not need to have a neutron absorption function. For this reason, the square pipe 11 is formed by, for example, extrusion molding using a boron-free material such as stainless steel), aluminum, or an aluminum alloy as a constituent material. By configuring the square pipe 11 as a boron-free material in this way, the range of material selection is widened, and a material having a higher strength than the boron-containing material can be used. For this reason, when the square pipe 11 made of a boron-free material is used as in this embodiment, the square pipe 11 can be made thinner than when a square pipe made of a boron-containing material is used. 15 and the holding member 20 can be easily secured.

  The fuel assembly 101 is stored in the cask 100 according to the present embodiment, for example, by the following procedure. First, with the lid body 2 removed, the basket 10 (square pipe 11) is inserted into the cavity 6 of the trunk body 1 from the opening 1a. Next, the pair of holding members 20 are inserted into the respective accommodation spaces 12 of the basket 10 from the openings 1 a to form the frame portions 25 in the accommodation spaces 12.

  Further, the neutron absorbing material 15 is inserted into the outer space 13 outside the frame portion 25 in the accommodating space 12 from the opening 1 a, and the neutron absorbing material 15 is arranged at a facing position facing the inner side surface of the square pipe 11. . In this case, since the neutron absorber 15 is disposed with a gap around it (see FIG. 3), the neutron absorber 15 can be easily inserted into the outer space 13. When the neutron absorber 15 is disposed, the movement of the neutron absorber 15 is restricted by the frame portion 25, and the neutron absorber 15 maintains the facing posture.

  When the above procedure is completed, the spent fuel assembly 101 is loaded from the opening 1a into the storage portion 26 inside the frame portion 25. Thereafter, the lid 2 is mounted on the upper portion of the trunk body 1 and the fuel assembly 101 is stored in the cask 100. Note that the storage procedure of the fuel assembly 101 is not limited to that described above. For example, after inserting the neutron absorber 15 into the storage space 12 of the basket 10, the holding member 20 may be disposed on the inside thereof, and the neutron absorber 15 may be held in an opposing posture.

According to this embodiment, the following effects can be obtained.
(1) The basket 10 formed by bundling a plurality of square pipes 11 divides the cavity 6 of the trunk body 1 into a plurality of receiving spaces 12 and faces each inner surface of the square pipe 11 so as to absorb flat neutrons. Each of the materials 15 is arranged, and the neutron absorber 15 is held by a pair of L-shaped holding members 20 facing the neutron absorber 15 and arranged in the accommodation space 12, and the fuel assembly 101 is stored. A portion 26 was formed. According to this configuration, since it is not necessary to fix the neutron absorber 15 to the square pipe 11, it is not necessary to provide the square pipe 11 with a groove for fixing the neutron absorber. Therefore, the neutron absorber 15 can be arranged in the accommodation space 12 with a simple configuration, and an increase in processing cost can be suppressed.

(2) Since the holding member 20 extending in the vertical direction has an L-shaped cross section, the holding member 20 can be easily formed by bending a flat plate, and the like in the rectangular parallelepiped housing space 12. The arrangement of the frame portion 25 is easy.
(3) Since the neutron absorber 15 is made of a boron-containing material and the cell structure (the plurality of square pipes 11) is made of a boron-free material, a high-strength material can be used as the cell structure. The cell structure can be easily thinned.
(4) Since the neutron absorber 15 is made of a material containing boron and the thin member 20 is made of a material not containing boron, the workability of the thin member 20 is good, and the thin member 20 has an L shape. It can be easily processed.

  By the way, in this embodiment, the cavity 6 is partitioned into a plurality of accommodating spaces 12 by the partition wall 14 (FIG. 3) constituting the square pipe 11, but the partition wall 14 is the outermost surface portion of the basket 10 at the peripheral surface portion of the cavity 6. Specify the outside. That is, as shown in FIG. 2, among the four partition walls 14 (first partition wall 141, second partition wall 142, third partition wall 143, and fourth partition wall 144) that form the accommodation space 12, The partition wall portion 143 and the fourth partition wall portion 144 define adjacent storage spaces 12, while the first partition wall portion 141 and the second partition wall portion 142 define the outermost part of the basket 10. Therefore, the accommodation space 12 adjacent to the first partition wall portion 141 and the second partition wall portion 142 does not exist, and the first partition wall portion 141 and the second partition wall portion 142 do not need to absorb neutrons. In consideration of this point, the installation of the neutron absorber 15 facing the inner surface of the first partition wall 141 and the inner surface of the second partition wall 142 may be omitted.

  FIG. 5 is an enlarged cross-sectional view of the accommodation space 12 showing an example thereof. In FIG. 5, not only the neutron absorber 15 facing the first side surface 111 and the neutron absorber 15 facing the second side surface 112 but also one thin member 20 is omitted. As described above, in the first embodiment, since the thin member 20 is configured to have an L-shaped cross section, the thin member 20 that does not require positioning of the neutron absorber 15 can be omitted. The installation space can be expanded.

(Second Embodiment)
Hereinafter, a second embodiment of the present invention will be described with reference to FIG. The second embodiment is different from the first embodiment in the shape of the holding member in the accommodation space 12. FIG. 6 is an enlarged view showing a main configuration of a radioactive substance storage container according to the second embodiment of the present invention, and corresponds to FIG. 3 of the first embodiment. In addition, the same code | symbol is attached | subjected to the location same as FIG. 3, and the difference with 1st Embodiment is mainly demonstrated below.

  As illustrated in FIG. 6, the holding member 30 has a rectangular frame shape in cross section, and the frame portion 25 is configured by the single holding member 30. The rectangle in this case includes not only a pure rectangle but also a case that is substantially equivalent to the rectangle. The holding member 30 can be configured by bending a thin plate having a predetermined thickness at a plurality of positions at a right angle and welding both ends thereof. Note that the right angle in this case includes not only a pure right angle but also an angle substantially equal to the right angle. The cross-sectional shape of the holding member 30 is substantially the same as the shape of the frame portion 25 (FIG. 3) configured by the L-shaped holding member 20. The material and thickness of the holding member 30 are the same as those of the holding member 20.

  In the outer space 13 of the holding member 30 in the accommodating space 12, the neutron absorbing material 15 is arranged facing the first side surface 111 to the fourth side surface 114 of the square pipe 11, and the neutron absorbing material 15 is held by the holding member 30. It is held in the opposite posture. A storage portion 26 is formed inside the holding member 30, and the fuel assembly 101 is accommodated in the storage portion 26. In the second embodiment, the neutron absorber 15 can be arranged as shown in FIG.

  In the second embodiment, the basket 10 formed by binding a plurality of square pipes 11 divides the cavity 6 of the trunk body 1 into a plurality of receiving spaces 12, and faces each inner side surface of the square pipe 11 to form a flat plate. The neutron absorbers 15 are respectively arranged, and the neutron absorbers 15 are connected to the inner side surface of the square pipe 11 by a frame-shaped holding member 30 having a rectangular section facing the neutron absorber 15 and arranged in the accommodation space 12. It was made to hold | maintain the close attitude | position close to and parallel to. Thereby, the neutron absorber 15 can be arrange | positioned in the accommodation space 12 with a simple structure, and the raise of processing cost can be suppressed.

  In addition, since the holding member 30 has a rectangular cross-sectional shape, the storage portion 26 can be formed in the housing space 12 simply by inserting the single holding member 30 into the housing space 12. The storage procedure 101 can be made efficient. Since the holding member 30 is configured in a frame shape, the storage portion 26 having a predetermined size can always be formed in the receiving space 12 regardless of the movement of the holding member 30 in the receiving space 12. For this reason, the neutron absorber 15 and the fuel assembly 101 can be easily inserted into the accommodation space 12.

(Modification)
In the above-described embodiment (FIGS. 3 to 6), in the state where the holding members 20, 30 are inserted into the accommodation space 12, the holding members 20, 30 are in the accommodation space 12 until they abut against the inner side surface of the square pipe 11. Is movable. You may make it restrict | limit the movement of this holding member 20 and 30 more. FIG. 7 is an enlarged view of a main part of the accommodation space 12 showing an example thereof. FIG. 7 is an example applied to the holding member 20 having an L-shaped cross section, and shows an example in which a single holding member 20 is arranged in the accommodation space 12.

  In FIG. 7, both end portions of the holding member 20 (end portions of the support portions 22 and 23) are bent outward (inner side surface of the square pipe 11) to form a bent portion 24. Thus, the support portions 22 and 23 of the holding member 20 are always arranged away from the inner side surface of the square pipe 11, and an outer space 13 in a predetermined range is formed between the support portions 22 and 23 and the inner side surface of the square pipe 11. it can. Thereby, the installation space of the neutron absorber 15 can be ensured in the accommodation space 12, and the neutron absorber 15 can be inserted easily. Further, by providing the bent portions 24 at both ends of the holding member 20, the rigidity of the holding member 20 is improved, and deformation due to bending of the holding member 20 or the like can be suppressed.

  In the above embodiment (FIGS. 3 to 6), the cross-sectional shape of the holding members 20 and 30 is made constant in the vertical direction, but is held so that the opening area (inlet area) on the insertion side of the fuel assembly 101 increases. The members 20 and 30 may be configured. FIG. 8 is a longitudinal sectional view of the holding members 20 and 30 showing an example thereof, and shows a state where the fuel assembly 101 is inserted. In FIG. 8, the upper end portions of the holding members 20 and 30 are bent toward the neutron absorber 15 on the outer side, and a bent portion 27 is formed.

  As a result, the storage portion 26 is enlarged at the upper end portions of the holding members 20 and 30, and the hooking at the time of insertion of the fuel assembly 101 can be suppressed, so that the fuel assembly 101 can be easily inserted into the storage portion 26. . Moreover, since the bending part 27 is located above the neutron absorber 15, the movement of the neutron absorber 15 to the opening 1a of the trunk body 1 can be restricted. The bending process of the holding members 20 and 30 is easy, and the entrance area can be easily increased as compared with the case where the end portion of the square pipe 11 is processed to increase the entrance area. In the example of FIG. 8, the holding members 20 and 30 are inserted after the neutron absorber 15 is inserted into the accommodation space 12.

  In the above embodiment, the present invention is applied to the transport or storage cask 100, but the present invention can also be applied to easily store radioactive materials other than the cask 100 such as a storage rack installed in a fuel pool. Therefore, the housing part for storing the radioactive substance may be configured by forming the cavity 6 in the body 1. Although the cavity 6 has a hollow cylindrical shape, the accommodating portion may have another shape (for example, a prismatic shape). The fuel assembly 101 may be not only used recycled fuel but also unused fuel.

  In the above embodiment, the basket 10 as the cell structure is configured by the plurality of square pipes 11 corresponding to the shape of the fuel assembly 101 (FIG. 2), and the cavity 6 is partitioned into the plurality of accommodation spaces 12. However, the cell structure may be constituted by other than the square pipe 11. For example, the cell structure may be configured by stacking a plurality of flat plates in a lattice shape and stacking them upward. In the example of the fuel storage rack, support plates are horizontally arranged at the upper and lower portions of the rack, and an opening for storing fuel is provided in each support plate, and the upper and lower openings are communicated with each other. The accommodation space may be configured by the formed space.

  In the above embodiment, the neutron absorber 15 having a rectangular shape as a whole is arranged at the facing position facing the inner surface of the cell structure. However, if the neutron absorber 15 is configured in a flat plate shape, The shape of the neutron absorber 15 is not limited to that described above.

  In the above embodiment, the frame portion 25 is configured in the accommodating space by the holding member 20 having an L-shaped cross section (FIGS. 3 to 5) or the holding member 30 having a rectangular frame shape (FIG. 6). As long as it is disposed in the accommodating space 12 so as to face 15 and hold the neutron absorber 15 and form the storage portion 26 of the fuel assembly 101, the holding member may have any configuration. For example, an opening may be provided in a part of the holding members 20 and 30 to reduce the weight. The holding member may be constituted by a simple plate-like member instead of a thin plate.

  In the said embodiment, although the neutron absorber 15 was comprised with the boron containing material and the cell structure (basket 10) and the holding members 20 and 30 were comprised with the boron non-containing material, other materials (for example, neutron absorption performance) The neutron absorber 15 may be constituted by a constituent material containing cadmium. At least one of the basket 10 and the holding members 20 and 30 can be made of a material having neutron absorption performance.

  In the above modification (FIG. 7), the position restricting portion is configured so as to constrain the position of the holding member 20 in the accommodating space 12 by providing the bent portion 24 at the end of the holding member 20, but the configuration of the position restricting portion. Is not limited to this. Further, the holding member 30 can be provided with a position restricting portion.

  In the above modification (FIG. 8), the bent portion 27 is provided at the upper end of the holding members 20 and 30 so that the opening area on the insertion side of the fuel assembly 101 is increased. The area may be increased.

  In the said embodiment (FIG. 5), the neutron absorber 15 is faced to the inner surface of the partition part 143,144 (inner partition part) arrange | positioned inside among the partition parts 141-144 which comprise the square pipe 11. FIG. The neutron absorber 15 is not arranged on the inner surface of the partition walls 111 and 112 (outer partition walls) arranged on the outermost part, but the arrangement pattern of the neutron absorber 15 is limited to this. Not.

  The above description is merely an example, and the present invention is not limited to the above-described embodiments and modifications unless the characteristics of the present invention are impaired. The constituent elements of the embodiment and the modified examples include those that can be replaced while maintaining the identity of the invention and that are obvious for replacement. That is, other forms conceivable within the scope of the technical idea of the present invention are also included in the scope of the present invention. Moreover, it is also possible to arbitrarily combine one or more of the above-described embodiments and modified examples.

6 cavity 10 basket 11 square pipe 12 accommodation space 13 outer space 15 neutron absorber 20 holding member 24 bent portion 26 storage portion 27 bent portion 30 holding member 100 cask 101 fuel assembly 111 first side surface 112 second side surface 113 third side surface 114 4th side wall 141 1st partition part 142 2nd partition part 143 3rd partition part 144 4th partition part

Claims (8)

A radioactive substance storage container for arranging and storing a plurality of fuel assemblies containing radioactive substances,
A containment section;
A cell structure that divides the accommodating portion into a plurality of accommodating spaces that accommodate the plurality of fuel assemblies; and
A flat neutron absorber that faces the inner surface of the cell structure and is movable with respect to the cell structure; and
Facing the neutron absorber , the cell structure and the neutron absorber are movably arranged, arranged in the accommodation space, hold the neutron absorber, and form a storage part for the fuel assembly A radioactive substance storage container. The radioactive substance storage container according to claim 1,
The accommodation space has a rectangular parallelepiped shape,
The radioactive substance storage container, wherein the holding member extends in an insertion direction of the fuel assembly and has an L-shaped cross section. The radioactive substance storage container according to claim 1,
The accommodation space has a rectangular parallelepiped shape,
The holding member extends in the insertion direction of the fuel assembly and has a rectangular frame shape in cross section. The radioactive substance storage container according to any one of claims 1 to 3,
The radioactive substance storage container, wherein the cell structure is made of a constituent material that does not contain a material having the neutron absorption performance. In the radioactive substance storage container according to any one of claims 1 to 4,
The radioactive substance storage container, wherein the holding member is made of a constituent material that does not include a material having the neutron absorption performance. In the radioactive substance storage container according to any one of claims 1 to 5,
The radioactive substance storage container according to claim 1, wherein the holding member has a position restricting portion that restricts a position of the holding member in the accommodation space. The radioactive substance storage container according to any one of claims 1 to 6,
The holding member has an inlet portion for inserting the fuel assembly into the accommodating space at an end portion, and the inlet portion is provided so that an opening area on the insertion side of the fuel assembly is increased. A radioactive substance storage container characterized by comprising: In the radioactive substance storage container according to any one of claims 1 to 7,
The cell structure has an outer partition wall disposed at the outermost portion, and an inner partition wall disposed inside the outer partition wall,
The radioactive substance storage container according to claim 1, wherein the neutron absorber is disposed facing the inner side surface of the inner partition wall portion, but is not disposed facing the inner side surface of the outer partition wall portion.

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