JP5501637B2 - Fuel assembly storage container - Google Patents

Description

  The present invention relates to a fuel assembly storage container that stores a fuel assembly used in a nuclear reactor.

  An assembly of nuclear fuel used in a nuclear power plant is called a fuel assembly. Since the fuel assembly loaded into the nuclear reactor and burned for a predetermined period and then removed from the nuclear reactor contains fission products (FP) and the like, it is usually cooled in a cooling pit such as a nuclear power plant for a predetermined period. . After that, the fuel assembly is stored in a fuel assembly storage container having a radiation shielding function and transported to a reprocessing facility by a vehicle or a ship, or reprocessed, or transported to an intermediate storage facility until reprocessing is performed. Stored.

  Usually, the fuel assembly storage container has a bottomed container body having an open top and a basket disposed in the container body. A plurality of fuel assemblies are arranged in the container body in a form in which a plurality of fuel assemblies are inserted in the longitudinal direction (axial direction) with respect to the basket. The upper opening of the container main body is closed by a lid member having a single lid, or a plurality of lids such as a primary lid and a secondary lid in a specification corresponding to the use of the container.

  In such a fuel assembly storage container, in the event of an impact during transportation or during an earthquake, the radial gap between the fuel assembly and the basket and the gap between the fuel assembly and the lid member A large impact load may act on the fuel assembly due to the collision between the fuel assembly and the basket, lid member, or container body due to the gap in the axial direction. Therefore, conventionally, Patent Document 1 discloses a fuel assembly storage container in which spacers are arranged in the radial gap between the fuel assembly and the basket and the axial gap between the fuel assembly and the lid member. (Metal sealed container) is disclosed.

Japanese Patent No. 3600551

  By the way, when the fuel assembly storage container receives an impact and the fuel assembly moves in the axial direction, the loads of all the fuel assemblies simultaneously act on the lid member and the bottom of the container body. For this reason, in the fuel assembly storage container, a high stress is generated in the lid member and the container body due to the load of all the fuel assemblies, and an excessive load is applied to the lid member and the container body. In this case, it may be necessary to use a higher-strength material for the lid member and the container body so as to be able to withstand the excessive load, and there is a possibility that the economy (production cost) may deteriorate.

  The present invention solves the above-described problems, and an object of the present invention is to provide a fuel assembly storage container that can relieve stress generated in the lid member and the container body due to the load of the moved fuel assembly.

  In order to achieve the above-described object, the fuel assembly storage container of the present invention has a bottomed container body having an open top and a lid member that closes the opening and is configured in a longitudinal shape. In a fuel assembly storage container in which a plurality of assemblies are stored with the end in the longitudinal direction facing the inner bottom surface of the container body and the inner wall surface of the lid member, each fuel assembly applies an external force in the longitudinal direction. In this case, load distribution means for dividing the load of the fuel assembly acting on the inner bottom surface of the container body or the inner wall surface of the lid member into a plurality of parts is provided.

  In the fuel assembly storage container according to the present invention, the load distribution means may be configured such that the end portion of the fuel assembly, a portion of the inner bottom surface of the container body facing the end portion of the fuel assembly, or the lid member The at least one of the portions of the inner wall faced with the end of the fuel assembly facing each other includes an inner bottom surface of the container main body, an inner wall surface of the lid member, and an end of the fuel assembly. It is characterized in that at least one of a convex portion and a concave portion, which makes an interval between them different for at least one of the fuel assemblies, is provided.

  In the fuel assembly storage container of the present invention, the convex portion is formed of a buffer member.

  In the fuel assembly storage container according to the present invention, the load distribution means may be configured such that the end portion of the fuel assembly, a portion of the inner bottom surface of the container body facing the end portion of the fuel assembly, or the lid member A buffer member having a different Young's modulus is provided on at least one of the portions of the inner wall face of the inner wall facing the end of the fuel assembly.

  Further, in the fuel assembly storage container of the present invention, the buffer members having different Young's moduli are the distances between the inner bottom surface of the container body and the inner wall surface of the lid member, and the end portions of all the fuel assemblies. Are formed in the same manner.

  According to the present invention, the generation time of the stress in the lid member and the container main body due to the load of the fuel assembly is dispersed, and the peak is smaller than that of the fuel assembly storage container without the load distribution means. The stress generated in the lid member and the container body can be relieved.

FIG. 1 is a schematic diagram showing an overall configuration of a fuel assembly storage container according to Embodiment 1 of the present invention. FIG. 2 is a cross-sectional view of the fuel assembly storage container according to Embodiment 1 of the present invention. FIG. 3 is an explanatory view showing a state where the fuel assembly storage container falls vertically. FIG. 4 is a diagram showing the stress when the fuel assembly storage container drops vertically. FIG. 5 is an explanatory diagram of a fuel assembly storage container according to Embodiment 2 of the present invention. FIG. 6 is an explanatory diagram of a fuel assembly storage container according to Embodiment 3 of the present invention. FIG. 7 is an explanatory diagram of a fuel assembly storage container according to Embodiment 4 of the present invention. FIG. 8 is an explanatory diagram of a fuel assembly storage container according to Embodiment 5 of the present invention.

  Embodiments according to the present invention will be described below in detail with reference to the drawings. Note that the present invention is not limited to the embodiments. 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.

  The fuel assembly storage container according to the present invention is suitable for a fuel assembly of a pressurized water nuclear plant (PWR: Pressurized Water Reactor), but may be a boiling water nuclear plant (BWR: Boiling Water Reactor) or the like. It does not exclude application to all nuclear plants. In addition, the fuel assembly storage container according to the present invention is particularly suitable during transportation of the fuel assembly, but application during storage is not excluded. Furthermore, the fuel assembly storage container according to the present invention is not limited to storage of the fuel assembly taken out from the nuclear reactor, but may be applied to storage of a fuel assembly that is newly manufactured and loaded into the nuclear reactor.

[Embodiment 1]
As shown in FIG. 1, the fuel assembly storage container 1 mainly stores a fuel assembly 10 (see FIG. 2) taken out from a nuclear reactor, and is used for transportation and storage of the fuel assembly 10. . The fuel assembly storage container 1 includes a bottomed container body 2 having an open top, a neutron shield 3 attached to the outside of the container body 2, and a lid member 4 that closes the opening of the container body 2. Yes.

  The container body 2 includes a cylindrical body portion and a bottom portion provided at the lower end of the body portion, and a container body inner space (also referred to as a cavity) 20 formed by the body portion and the bottom portion is a fuel assembly. This is an area for storing the body 10. A basket 5 having a plurality of cells 51 partitioned in a lattice shape is arranged in the container body inner space 20. The basket 5 is configured by combining a plurality of square pipes 50 having a cross-sectional outer shape and a cross-sectional inner shape of a rectangular shape (substantially square shape) in a bundle in the first embodiment. A cell 51 is formed. The basket 5 is arranged in the container body inner space 20 and stores the individual fuel assemblies 10 in the respective cells 51.

  The container body 2 has a function of shielding γ rays from the fuel assembly 10 housed in the container body inner space 20. The neutron shield 3 is provided with a neutron shield for shielding neutrons. Further, a spacer 6 interposed between the inner peripheral wall of the container body 2 and the basket 5 is disposed in the container body inner space 20 of the container body 2. The spacer 6 transmits the decay heat from the fuel assembly 10 stored in the basket 5 to the container body 2. This decay heat is released into the atmosphere via the container body 2 and the neutron shield 3.

  The lid member 4 has a primary lid 41 and a secondary lid 42. The primary lid 41 is attached to the upper opening 21 of the container body 2 after storing the fuel assembly 10 in the basket 5 disposed in the container body space 20 of the container body 2. The secondary lid 42 is attached to the opening 21 of the container body 2 so as to cover the outside of the primary lid 41. The lid member 4 seals the container body inner space 20 of the container body 2 with the primary lid 41 and the secondary lid 42. Although not clearly shown in the figure, the lid member 4 may have a tertiary lid that covers the outside of the secondary lid 42 depending on the specification.

  As shown in FIG. 2, the fuel assembly 10 is configured by bundling a plurality of fuel rods 11 formed in a longitudinal shape by a plurality of support grids 12. Nozzles 13 are disposed at both ends of the fuel rod 11, respectively. This nozzle 13 becomes the end of the fuel assembly 10. Each fuel assembly 10 is also formed with the same dimension L in the length direction. As shown in FIG. 2, the fuel assembly 10 housed in the container body inner space 20 of the container body 2 has the nozzle 13 forming one end thereof facing the inner wall surface 41 a of the primary lid 41 that is the lid member 4. The nozzle 13 forming the other end faces the inner bottom surface 22 as the bottom surface in the container body inner space 20 of the container body 2. In FIG. 2, the basket 5 is omitted.

  Thus, in the fuel assembly storage container 1 that stores a plurality of fuel assemblies 10, as shown in FIG. 2, it is the inner wall surface 41 a of the primary lid 41 (lid member 4), and the end of the fuel assembly 10. A load distribution means is provided at a portion facing the portion (nozzle 13). In the first embodiment, the load distribution means is configured as a convex portion 100 provided on the inner wall surface 41 a of the primary lid 41. The convex portion 100 faces the nozzle 13 which is an end portion of the fuel assembly 10 and is provided so as to protrude downward from the inner wall surface 41a (the inner bottom surface 22 of the container body 2).

  The convex portion 100 is provided corresponding to at least one fuel assembly 10. For example, at least one of the convex portions 100 provided corresponding to all the fuel assemblies 10 is formed with different projecting dimensions H from the inner wall surface 41a. Further, for example, the protrusions 100 provided corresponding to a plurality selected from all of the fuel assemblies 10 are all formed with the same protruding dimension H from the inner wall surface 41a, or at least one of the protrusions 100 is internal. It is formed with different projecting dimensions H from the wall surface 41a. Moreover, the convex part 100 similarly formed in the protrusion dimension H may be provided in the inner wall surface 41a continuously and integrally.

  That is, the convex portion 100 serving as the load distribution means is configured such that the inner bottom surface 22 of the container main body 2 and the primary lid 41 of at least one fuel assembly 10 in a state where the fuel assembly 10 is stored in the fuel assembly storage container 1. The distance h between the inner wall surface 41 a and the end (nozzle 13) is made different from the same distance h in the other fuel assemblies 10.

  A state in which the fuel assembly storage container 1 having the convex portion 100 as such load distribution means drops vertically from the bottom of the container body 2 will be described with reference to FIG. 3A shows a state before the vertical drop, FIG. 3B shows a state during the vertical drop, and FIG. 3C reaches the fixed surface (floor surface, ground, etc.) G. The state immediately after is shown.

  As shown in FIG. 3A, the lower ends (nozzles 13) of all the fuel assemblies 10 are in contact with the inner bottom surface 22 of the container body 2 before the vertical drop. As shown in FIG. 3 (b), the fuel assembly storage container 1 has a mass larger than that of the fuel assembly 10 in the middle of the vertical fall. The fuel assembly 10 is applied with an external force upward in the longitudinal direction, and its upper end (nozzle 13) contacts the convex portion 100 or the inner wall surface 41 a of the primary lid 41. For this reason, the lower end (nozzle 13) of the fuel assembly 10 is separated from the inner bottom surface 22 of the container main body 2 by the distance h (see FIG. 2) in the middle of the vertical fall. As shown in FIG. 3C, in a state immediately after the fuel assembly storage container 1 reaches the fixed surface G, all the fuel assemblies 10 are given external force downward in the longitudinal direction. The lower end (nozzle 13) collides with the inner bottom surface 22 side of the container body 2. At this time, the lower end (nozzle 13) of the fuel assembly 10 formed with the smallest interval h collides with the inner bottom surface 22 of the container body 2 first. That is, the lower end (nozzle 13) of the fuel assembly 10 collides with the inner bottom surface 22 of the container main body 2 in the order in which the interval h is formed to be smaller.

  Although not shown in the figure, when the fuel assembly storage container 1 reaches the fixed surface G, the fuel assembly 10 after colliding with the inner bottom surface 22 of the container body 2 is placed on the inner bottom surface 22 of the container body 2. Then, it bounces upward and an external force is applied upward in the longitudinal direction, and this time, the upper end (nozzle 13) collides with the primary lid 41 side. Also at this time, the upper end (nozzle 13) of the fuel assembly 10 formed with the smallest interval h collides first with the convex portion 100 or the inner wall surface 41a of the primary lid 41. That is, the upper end (nozzle 13) of the fuel assembly 10 collides with the convex portion 100 or the inner wall surface 41 a of the primary lid 41 in the order in which the interval h is formed smaller.

  Here, the stress generated in the fuel assembly storage container 1 over time after the fuel assembly storage container 1 reaches the fixed surface G will be described with reference to FIG. FIG. 4A shows the case of the fuel assembly storage container 1 having the load distribution means (convex portion 100), and FIG. 4B shows the conventional fuel assembly storage container having no load distribution means. Show the case.

  As shown in FIG. 4A, when the load distribution means (convex portion 100) is provided, the end (nozzle 13) of the fuel assembly 10 collides in the order in which the interval h is formed to be small, so that there is a time difference in the collision. Arise. For this reason, the generation time of the stress in the lid member 4 and the container body 2 due to the load of the fuel assembly 10 is dispersed, and the peak is reduced. On the other hand, when there is no load distribution means (convex part 100), since the ends (nozzles 13) of all the fuel assemblies 10 collide simultaneously, there is no time difference in the collision. For this reason, the peak of stress in the lid member and the container main body caused by the load of the fuel assembly is large.

  As described above, in the fuel assembly storage container 1 according to the first embodiment, when each stored fuel assembly 10 is applied with an external force in the longitudinal direction, the load distribution means (convex portion 100) The load of the fuel assembly 10 acting on the inner bottom surface 22 of the container main body 2 or the inner wall surface 41a of the primary lid 41 is dispersed in a plurality. That is, the time until the load of the fuel assembly 10 is applied to the inner bottom surface 22 of the container body 2 or the inner wall surface 41a of the primary lid 41 is dispersed into a plurality of times.

  As a result, the generation time of stress in the lid member 4 and the container body 2 due to the load of the fuel assembly 10 is dispersed, and the peak thereof is smaller than that of a conventional fuel assembly storage container having no load distribution means. As a result, the stress generated in the lid member 4 and the container body 2 can be relaxed.

  Note that the load distribution means of the fuel assembly storage container 1 in the first embodiment described above is not limited to the convex portion 100, and the fuel assembly 10 is stored in the fuel assembly storage container 1 by a concave portion (not shown). In this state, for at least one fuel assembly 10, the distance h between the inner bottom surface 22 of the container body 2 and the inner wall surface 41 a of the primary lid 41 and the end (nozzle 13) is set to the same distance in the other fuel assemblies 10. It may be different from h. Further, with both the convex portion 100 and the concave portion, in the state where the fuel assembly 10 is stored in the fuel assembly storage container 1, the inner bottom surface 22 of the container main body 2 and the inside of the primary lid 41 are at least one fuel assembly 10. The distance h between the wall surface 41 a and the end (nozzle 13) may be different from the same distance h in the other fuel assemblies 10.

  Further, the convex portion 100 (or the concave portion) of the load distribution means of the fuel assembly storage container 1 in the first embodiment described above may be formed integrally with the primary lid 41. Further, the convex portion 100 of the load distribution means of the fuel assembly storage container 1 in the first embodiment described above may be formed separately from the primary lid 41.

  When the convex part 100 of the load distribution means is formed separately from the primary lid 41, it is preferable that the convex part 100 is constituted by a buffer member. By constituting the convex part 100 with a buffer member, the impact when the fuel assembly 10 collides with the convex part 100 can be reduced, and the stress generated in the lid member 4 and the container body 2 can be further reduced. It becomes possible.

  In addition, although Embodiment 1 mentioned above demonstrated the effect | action and effect about the state which the fuel assembly storage container 1 falls vertically from the bottom part of the container main body 2, it is not this limitation. For example, even if each fuel assembly 10 stored in a state where the fuel assembly storage container 1 is placed horizontally is applied with an external force in the longitudinal direction (horizontal direction), the load distribution means ( By the convex portion 100), the time until the load of the fuel assembly 10 is applied to the inner bottom surface 22 of the container body 2 or the inner wall surface 41a of the primary lid 41 can be divided into a plurality of times. As a result, the generation time of stress in the lid member 4 and the container body 2 due to the load of the fuel assembly 10 is dispersed, and the peak thereof is smaller than that of a conventional fuel assembly storage container having no load distribution means. As a result, the stress generated in the lid member 4 and the container body 2 can be relaxed.

[Embodiment 2]
In the second embodiment described below, the same parts as those in the first embodiment described above are denoted by the same reference numerals and description thereof is omitted.

  In the second embodiment, the load distribution means is configured as a convex portion 100 provided on the inner bottom surface 22 of the container body 2 as shown in FIG. The convex portion 100 faces the nozzle 13 that is an end portion of the fuel assembly 10, and is provided so as to protrude upward from the inner bottom surface 22 (the inner wall surface 41 a of the primary lid 41).

  The convex portion 100 is provided corresponding to at least one fuel assembly 10. For example, at least one of the convex portions 100 provided corresponding to all the fuel assemblies 10 is formed with different projecting dimensions H from the inner bottom surface 22. Further, for example, the protrusions 100 provided corresponding to a plurality selected from all the fuel assemblies 10 are all formed with the same projecting dimension H from the inner bottom surface 22, or at least one of the protrusions 100 is internal. The protrusions H from the bottom surface 22 are formed with different dimensions. Moreover, the convex part 100 similarly formed with the protruding dimension H may be provided on the inner bottom surface 22 continuously and integrally.

  That is, the convex portion 100 serving as the load distribution means is configured such that the inner bottom surface 22 of the container main body 2 and the primary lid 41 of at least one fuel assembly 10 in a state where the fuel assembly 10 is stored in the fuel assembly storage container 1. The distance h between the inner wall surface 41 a and the end (nozzle 13) is made different from the same distance h in the other fuel assemblies 10.

  A state in which the fuel assembly storage container 1 having the convex portion 100 as such load distribution means drops vertically from the bottom of the container body 2 will be described with reference to FIG. 5A shows a state before the vertical drop, FIG. 5B shows a state during the vertical drop, and FIG. 5C reaches the fixed surface (floor surface, ground, etc.) G. The state immediately after is shown.

  As shown in FIG. 5A, the lower end (nozzle 13) of the fuel assembly 10 is in contact with the convex portion 100 in a state before the vertical drop. As shown in FIG. 5 (b), the fuel assembly storage container 1 is larger in mass than the fuel assembly 10 in the middle of the vertical fall. The fuel assembly 10 is applied with an external force upward in the longitudinal direction, and its upper end (nozzle 13) contacts the inner wall surface 41 a of the primary lid 41. For this reason, the lower end (nozzle 13) of the fuel assembly 10 is separated from the convex portion 100 or the inner bottom surface 22 of the container main body 2 by the interval h in the state of being vertically dropped. As shown in FIG. 5C, in the state immediately after the fuel assembly storage container 1 reaches the fixed surface G, all the fuel assemblies 10 are given external force downward in the longitudinal direction. The lower end (nozzle 13) collides with the convex portion 100 or the inner bottom surface 22 side of the container body 2. At this time, the lower end (nozzle 13) of the fuel assembly 10 formed with the smallest interval h collides with the convex portion 100 first. That is, the lower end (nozzle 13) of the fuel assembly 10 collides with the convex portion 100 or the inner bottom surface 22 of the container main body 2 in the order in which the interval h is formed smaller.

  When the drop distance of the fuel assembly storage container 1 is short, even if all the fuel assemblies 10 are given an external force upward in the longitudinal direction in FIG. ) May not contact the inner wall surface 41a of the primary lid 41. Even in such a case, as shown in FIG. 5C, in the state immediately after the fuel assembly storage container 1 reaches the fixed surface G, the fuel assembly 10 having the smallest interval h is formed. The lower end (nozzle 13) of this collides with the convex part 100 first. That is, the lower end (nozzle 13) of the fuel assembly 10 collides with the convex portion 100 or the inner bottom surface 22 of the container main body 2 in the order in which the interval h is formed smaller.

  Although not clearly shown in the drawing, when the fuel assembly storage container 1 reaches the fixed surface G, the fuel assembly 10 after colliding with the convex portion 100 or the inner bottom surface 22 of the container body 2 has the convex portion 100. Alternatively, an external force is applied by bouncing upward at the inner bottom surface 22 of the container body 2 and upward in the longitudinal direction, and the upper end (nozzle 13) now collides with the primary lid 41 side. Also at this time, the upper end (nozzle 13) of the fuel assembly 10 formed with the smallest interval h collides with the inner wall surface 41a of the primary lid 41 first. That is, the upper end (nozzle 13) of the fuel assembly 10 collides with the inner wall surface 41 a of the primary lid 41 in the order in which the interval h is formed smaller.

  As described above, in the fuel assembly storage container 1 of the second embodiment, when each stored fuel assembly 10 is applied with an external force in the longitudinal direction, the load distribution means (convex portion 100) The load of the fuel assembly 10 acting on the inner bottom surface 22 of the container main body 2 or the inner wall surface 41a of the primary lid 41 is dispersed in a plurality. That is, the time until the load of the fuel assembly 10 is applied to the inner bottom surface 22 of the container body 2 or the inner wall surface 41a of the primary lid 41 is dispersed into a plurality of times.

  As a result, the generation time of stress in the lid member 4 and the container body 2 due to the load of the fuel assembly 10 is dispersed, and the peak thereof is smaller than that of a conventional fuel assembly storage container having no load distribution means. As a result, the stress generated in the lid member 4 and the container body 2 can be relaxed.

  Note that the load distribution means of the fuel assembly storage container 1 according to the second embodiment described above is not limited to the convex portion 100, and the fuel assembly 10 is stored in the fuel assembly storage container 1 by a concave portion (not shown). In this state, for at least one fuel assembly 10, the distance h between the inner bottom surface 22 of the container body 2 and the inner wall surface 41 a of the primary lid 41 and the end (nozzle 13) is set to the same distance in the other fuel assemblies 10. It may be different from h. Further, with both the convex portion 100 and the concave portion, in the state where the fuel assembly 10 is stored in the fuel assembly storage container 1, the inner bottom surface 22 of the container main body 2 and the inside of the primary lid 41 are at least one fuel assembly 10. The distance h between the wall surface 41 a and the end (nozzle 13) may be different from the same distance h in the other fuel assemblies 10.

  Further, the convex portion 100 (or the concave portion) of the load distribution means of the fuel assembly storage container 1 in the second embodiment described above may be formed integrally with the container body 2. Further, the convex portion 100 of the load distribution means of the fuel assembly storage container 1 in the second embodiment described above may be formed separately from the container main body 2.

  When the convex part 100 of the load distribution means is formed separately from the container main body 2, it is preferable that the convex part 100 is constituted by a buffer member. By constituting the convex part 100 with a buffer member, the impact when the fuel assembly 10 collides with the convex part 100 can be reduced, and the stress generated in the lid member 4 and the container body 2 can be further reduced. It becomes possible.

  In addition, in Embodiment 2 mentioned above, although the operation | movement and effect about the state which the fuel assembly storage container 1 falls vertically from the bottom part of the container main body 2 were demonstrated, it is not this limitation. For example, even if each fuel assembly 10 stored in a state where the fuel assembly storage container 1 is placed horizontally is applied with an external force in the longitudinal direction (horizontal direction), the load distribution means ( By the convex portion 100), the time until the load of the fuel assembly 10 is applied to the inner bottom surface 22 of the container body 2 or the inner wall surface 41a of the primary lid 41 can be divided into a plurality of times. As a result, the generation time of stress in the lid member 4 and the container body 2 due to the load of the fuel assembly 10 is dispersed, and the peak thereof is smaller than that of a conventional fuel assembly storage container having no load distribution means. As a result, the stress generated in the lid member 4 and the container body 2 can be relaxed.

[Embodiment 3]
In the third embodiment described below, the same parts as those in the above-described first embodiment are denoted by the same reference numerals and description thereof is omitted.

  In the third embodiment, the load distribution means is configured as a convex portion 100 provided at the upper end (nozzle 13) of the fuel assembly 10, as shown in FIG. The convex portion 100 faces the inner wall surface 41a of the primary lid 41 and is provided so as to protrude from the upper end (nozzle 13) of the fuel assembly 10 upward (the inner wall surface 41a of the primary lid 41).

  The convex portion 100 is provided corresponding to at least one fuel assembly 10. For example, at least one of the convex portions 100 provided corresponding to all the fuel assemblies 10 is formed with different projecting dimensions H from the nozzles 13. Further, for example, the protrusions 100 provided corresponding to a plurality selected from all the fuel assemblies 10 are all formed with the same protruding dimension H from the nozzle 13, or at least one of the protrusions 100 is the nozzle 13. Are formed with different projecting dimensions H.

  That is, the convex portion 100 serving as the load distribution means is configured such that the inner bottom surface 22 of the container main body 2 and the primary lid 41 of at least one fuel assembly 10 in a state where the fuel assembly 10 is stored in the fuel assembly storage container 1. The distance h between the inner wall surface 41 a and the end (nozzle 13) is made different from the same distance h in the other fuel assemblies 10.

  A state in which the fuel assembly storage container 1 having the convex portion 100 as such load distribution means drops vertically from the bottom of the container body 2 will be described with reference to FIG. 6A shows a state before the vertical drop, FIG. 6B shows a state during the vertical drop, and FIG. 6C reaches the fixed surface (floor surface, ground, etc.) G. The state immediately after is shown.

  As shown in FIG. 6A, the lower ends (nozzles 13) of all the fuel assemblies 10 are in contact with the inner bottom surface 22 of the container body 2 before the vertical drop. Then, as shown in FIG. 6 (b), the fuel assembly storage container 1 is larger in mass than the fuel assembly 10 in the middle of the vertical fall. The fuel assembly 10 is applied with an external force upward in the longitudinal direction, and its upper end (nozzle 13) or convex portion 100 comes into contact with the inner wall surface 41 a of the primary lid 41. For this reason, in the middle of the vertical fall, the lower end (nozzle 13) of the fuel assembly 10 is separated from the inner bottom surface 22 of the container body 2 by the interval h. Then, as shown in FIG. 6C, in the state immediately after the fuel assembly storage container 1 reaches the fixed surface G, all the fuel assemblies 10 are given external force downward in the longitudinal direction. The lower end (nozzle 13) collides with the inner bottom surface 22 side of the container body 2. At this time, the lower end (nozzle 13) of the fuel assembly 10 formed with the smallest interval h collides first with the inner bottom surface 22 of the container body 2. That is, the lower end (nozzle 13) of the fuel assembly 10 collides with the inner bottom surface 22 of the container body 2 in the order in which the interval h is formed smaller.

  Although not shown in the figure, when the fuel assembly storage container 1 reaches the fixed surface G, the fuel assembly 10 after colliding with the inner bottom surface 22 of the container body 2 is placed on the inner bottom surface 22 of the container body 2. Then, an external force is applied by rebounding upward in the longitudinal direction, and the upper end (nozzle 13) or the convex portion 100 now collides with the primary lid 41 side. Also at this time, the convex portion 100 of the upper end (nozzle 13) of the fuel assembly 10 formed with the smallest interval h collides with the inner wall surface 41a of the primary lid 41 first. In other words, the upper end (nozzle 13) of the fuel assembly 10 or the convex portion 100 collides with the inner wall surface 41 a of the primary lid 41 in the order in which the interval h is formed smaller.

  Thus, in the fuel assembly storage container 1 of the third embodiment, when each stored fuel assembly 10 is given an external force in the longitudinal direction, the load distribution means (convex portion 100) The load of the fuel assembly 10 acting on the inner bottom surface 22 of the container main body 2 or the inner wall surface 41a of the primary lid 41 is dispersed in a plurality. That is, the time until the load of the fuel assembly 10 is applied to the inner bottom surface 22 of the container body 2 or the inner wall surface 41a of the primary lid 41 is dispersed into a plurality of times.

  As a result, the generation time of stress in the lid member 4 and the container body 2 due to the load of the fuel assembly 10 is dispersed, and the peak thereof is smaller than that of a conventional fuel assembly storage container having no load distribution means. As a result, the stress generated in the lid member 4 and the container body 2 can be relaxed.

  In addition, the convex part 100 of the load distribution means of the fuel assembly storage container 1 in the above-described third embodiment may be formed integrally with the nozzle 13 of the fuel assembly 10. Further, the convex portion 100 of the load distribution means of the fuel assembly storage container 1 in the above-described third embodiment may be formed separately from the nozzle 13 of the fuel assembly 10.

  When the convex portion 100 of the load distribution means is formed separately from the nozzle 13 of the fuel assembly 10, it is preferable that the convex portion 100 is constituted by a buffer member. By constituting the convex portion 100 with a buffer member, the impact when the fuel assembly 10 collides with the inner wall surface 41a of the primary lid 41 can be reduced, and the stress generated in the lid member 4 and the container body 2 can be further increased. It can be mitigated.

  In the third embodiment described above, the operation and effect of the state where the fuel assembly storage container 1 drops vertically from the bottom of the container body 2 has been described, but this is not restrictive. For example, even if each fuel assembly 10 stored in a state where the fuel assembly storage container 1 is placed horizontally is applied with an external force in the longitudinal direction (horizontal direction), the load distribution means ( By the convex portion 100), the time until the load of the fuel assembly 10 is applied to the inner bottom surface 22 of the container body 2 or the inner wall surface 41a of the primary lid 41 can be divided into a plurality of times. As a result, the generation time of stress in the lid member 4 and the container body 2 due to the load of the fuel assembly 10 is dispersed, and the peak thereof is smaller than that of a conventional fuel assembly storage container having no load distribution means. As a result, the stress generated in the lid member 4 and the container body 2 can be relaxed.

[Embodiment 4]
In the fourth embodiment described below, the same parts as those in the first embodiment described above are denoted by the same reference numerals, and description thereof is omitted.

  In the fourth embodiment, the load distribution means is configured as a convex portion 100 provided at the lower end (nozzle 13) of the fuel assembly 10, as shown in FIG. The convex portion 100 faces the inner wall surface 41a of the primary lid 41, and is provided so as to protrude downward from the lower end (nozzle 13) of the fuel assembly 10 toward the inner bottom surface 22 of the container body 2.

  The convex portion 100 is provided corresponding to at least one fuel assembly 10. For example, at least one of the convex portions 100 provided corresponding to all the fuel assemblies 10 is formed with different projecting dimensions H from the nozzles 13. Further, for example, the protrusions 100 provided corresponding to a plurality selected from all the fuel assemblies 10 are all formed with the same protruding dimension H from the nozzle 13, or at least one of the protrusions 100 is the nozzle 13. Are formed with different projecting dimensions H.

  That is, the convex portion 100 serving as the load distribution means is configured such that the inner bottom surface 22 of the container main body 2 and the primary lid 41 of at least one fuel assembly 10 in a state where the fuel assembly 10 is stored in the fuel assembly storage container 1. The distance h between the inner wall surface 41 a and the end (nozzle 13) is made different from the same distance h in the other fuel assemblies 10.

  A state in which the fuel assembly storage container 1 having the convex portion 100 as such load distribution means drops vertically from the bottom of the container body 2 will be described with reference to FIG. 7A shows a state before the vertical drop, FIG. 7B shows a state during the vertical drop, and FIG. 7C reaches the fixed surface (floor surface, ground, etc.) G. The state immediately after is shown.

  As shown in FIG. 7A, the lower ends (nozzles 13) or the convex portions 100 of all the fuel assemblies 10 are in contact with the inner bottom surface 22 of the container body 2 before the vertical drop. Then, as shown in FIG. 7 (b), the fuel assembly storage container 1 has a mass larger than that of the fuel assembly 10 in the middle of the vertical fall, and therefore, in the container body inner space 20 of the container body 2, The fuel assembly 10 is applied with an external force upward in the longitudinal direction, and its upper end (nozzle 13) contacts the inner wall surface 41 a of the primary lid 41. For this reason, the lower end (nozzle 13) or the convex part 100 of the fuel assembly 10 is separated from the inner bottom surface 22 of the container main body 2 by the interval h in the state of being vertically dropped. Then, as shown in FIG. 7C, in a state immediately after the fuel assembly storage container 1 reaches the fixed surface G, all the fuel assemblies 10 are given external force downward in the longitudinal direction. The lower end (nozzle 13) or the convex portion 100 collides with the inner bottom surface 22 of the container body 2. At this time, the convex portion 100 at the lower end (nozzle 13) of the fuel assembly 10 formed with the smallest interval h collides with the inner bottom surface 22 first. That is, the lower end (nozzle 13) of the fuel assembly 10 or the convex portion 100 collides with the inner bottom surface 22 of the container body 2 in the order in which the distance h is formed smaller.

  When the drop distance of the fuel assembly storage container 1 is short, even if all the fuel assemblies 10 are given external force upward in the longitudinal direction in FIG. ) May not contact the inner wall surface 41a of the primary lid 41. Even in such a case, as shown in FIG. 7C, in the state immediately after the fuel assembly storage container 1 reaches the fixed surface G, the fuel assembly 10 having the smallest interval h is formed. The convex portion 100 at the lower end (nozzle 13) of this collides with the inner bottom surface 22 first. That is, the lower end (nozzle 13) of the fuel assembly 10 or the convex portion 100 collides with the inner bottom surface 22 of the container body 2 in the order in which the distance h is formed smaller.

  Although not clearly shown in the figure, when the fuel assembly storage container 1 reaches the fixed surface G, the fuel assembly 10 after colliding with the inner bottom surface 22 of the container body 2 has the convex portion 100 or the container body 2. Bounces upward at the inner bottom surface 22 and an external force is applied upward in the longitudinal direction, and the upper end (nozzle 13) now collides with the primary lid 41 side. Also at this time, the upper end (nozzle 13) of the fuel assembly 10 formed with the smallest interval h collides with the inner wall surface 41a of the primary lid 41 first. That is, the upper end (nozzle 13) of the fuel assembly 10 collides with the inner wall surface 41 a of the primary lid 41 in the order in which the interval h is formed smaller.

  As described above, in the fuel assembly storage container 1 according to the fourth embodiment, when an external force is applied to the stored fuel assemblies 10 in the longitudinal direction, the load distribution means (convex portion 100) The load of the fuel assembly 10 acting on the inner bottom surface 22 of the container main body 2 or the inner wall surface 41a of the primary lid 41 is dispersed in a plurality. That is, the time until the load of the fuel assembly 10 is applied to the inner bottom surface 22 of the container body 2 or the inner wall surface 41a of the primary lid 41 is dispersed into a plurality of times.

  As a result, the generation time of stress in the lid member 4 and the container body 2 due to the load of the fuel assembly 10 is dispersed, and the peak thereof is smaller than that of a conventional fuel assembly storage container having no load distribution means. As a result, the stress generated in the lid member 4 and the container body 2 can be relaxed.

  Note that the convex portion 100 of the load distribution means of the fuel assembly storage container 1 in the above-described fourth embodiment may be formed integrally with the nozzle 13 of the fuel assembly 10. Further, the convex portion 100 of the load distribution means of the fuel assembly storage container 1 in the above-described fourth embodiment may be formed separately from the nozzle 13 of the fuel assembly 10.

  When the convex portion 100 of the load distribution means is formed separately from the nozzle 13 of the fuel assembly 10, it is preferable that the convex portion 100 is constituted by a buffer member. By configuring the convex portion 100 with a buffer member, the impact when the fuel assembly 10 collides with the inner bottom surface 22 of the container body 2 can be reduced, and the stress generated in the lid member 4 and the container body 2 can be further increased. It can be mitigated.

In the fourth embodiment described above, the operation and effect of the state in which the fuel assembly storage container 1 drops vertically from the bottom of the container body 2 has been described, but this is not restrictive. For example,
Even when each fuel assembly 10 stored in a state where the fuel assembly storage container 1 is placed horizontally is applied with an external force in the longitudinal direction (horizontal direction), the load distribution means (convex portion) 100), the time until the load of the fuel assembly 10 is applied to the inner bottom surface 22 of the container body 2 or the inner wall surface 41a of the primary lid 41 can be divided into a plurality of times. As a result, the generation time of stress in the lid member 4 and the container body 2 due to the load of the fuel assembly 10 is dispersed, and the peak thereof is smaller than that of a conventional fuel assembly storage container having no load distribution means. As a result, the stress generated in the lid member 4 and the container body 2 can be relaxed.

  By the way, in the fuel assembly storage container 1 of the first embodiment described above, the convex portion 100 (or the concave portion) of the load distribution means is provided on the inner wall surface 41a of the primary lid 41. In the fuel assembly storage container 1, the convex portion 100 (or recess) of the load distribution means is provided on the inner bottom surface 22 of the container body 2, and in the fuel assembly storage container 1 of the above-described third embodiment, the load The convex portion 100 of the dispersion means is provided at the upper end (nozzle 13) of the fuel assembly 10, and in the fuel assembly storage container 1 of the fourth embodiment described above, the convex portion 100 of the load dispersion means is the fuel assembly. It is provided at the lower end (nozzle 13) of the body 10. Not limited to this configuration, the load distribution means may be an end of the fuel assembly 10 (nozzle 13), a portion of the inner bottom surface 22 of the container body 2 facing the end of the fuel assembly 10, or the inside of the lid member 4. It may be provided in a form in which at least one of the portions of the wall surface 41a where the end of the fuel assembly 10 is opposed, that is, the first to fourth embodiments are selectively combined.

[Embodiment 5]
In the fifth embodiment described below, the same parts as those in the above-described first embodiment are denoted by the same reference numerals, and description thereof is omitted.

  In the fifth embodiment, the load distribution means is configured as a convex portion 100 provided on the inner bottom surface 22 of the container body 2 as shown in FIG. The convex portion 100 faces the nozzle 13 that is an end portion of the fuel assembly 10, and is provided so as to protrude upward from the inner bottom surface 22 (the inner wall surface 41 a of the primary lid 41).

  The convex portions 100 are provided corresponding to all the fuel assemblies 10 or a plurality of selected fuel assemblies 10. All of the convex portions 100 are formed with the same protruding dimension H from the inner wall surface 41a. That is, in the state where the fuel assembly 10 is stored in the fuel assembly storage container 1, the inner bottom surface 22 of the container body 2, the inner wall surface 41 a of the primary lid 41, and the end portion of the fuel assembly 10 corresponding to the convex portion 100. The distance h from (nozzle 13) is the same. Furthermore, the convex part 100 is comprised with the buffer member which consists of an elastic material from which Young's modulus differs. In addition, the convex part 100 may be provided in the inner wall surface 41a continuously.

  A state in which the fuel assembly storage container 1 having the convex portion 100 as such load distribution means drops vertically from the bottom of the container main body 2 will be described with reference to FIG. 8A shows a state before the vertical drop, FIG. 8B shows a state during the vertical drop, and FIG. 8C reaches the fixed surface (floor surface, ground, etc.) G. The state immediately after is shown.

  As shown in FIG. 8A, the lower end (nozzle 13) of the fuel assembly 10 is in contact with the convex portion 100 before the vertical drop. Then, as shown in FIG. 8B, in the state of being dropped vertically, the fuel assembly storage container 1 has a larger mass than the fuel assembly 10, and therefore, in the container body inner space 20 of the container body 2, The fuel assembly 10 is applied with an external force upward in the longitudinal direction, and its upper end (nozzle 13) contacts the inner wall surface 41 a of the primary lid 41. For this reason, the lower end (nozzle 13) of the fuel assembly 10 is separated from the convex portion 100 or the inner bottom surface 22 of the container main body 2 by the interval h in the state of being vertically dropped. Then, as shown in FIG. 8C, in the state where the fuel assembly storage container 1 has reached the fixed surface G, all the fuel assemblies 10 are given external force downward in the longitudinal direction, The lower end (nozzle 13) collides with the convex portion 100 or the inner bottom surface 22 side of the container body 2. At this time, the fuel assembly 10 corresponding to the position of the convex portion 100 collides with the convex portion 100.

  When the drop distance of the fuel assembly storage container 1 is short, even if all the fuel assemblies 10 are applied with an external force upward in the longitudinal direction in FIG. ) May not contact the inner wall surface 41a of the primary lid 41. Even in such a case, as shown in FIG. 8C, when the fuel assembly storage container 1 has reached the fixed surface G, the fuel assembly 10 corresponding to the position of the convex portion 100 is convex. Collide with part 100.

  Although not clearly shown in the figure, when the fuel assembly storage container 1 reaches the fixed surface G, the fuel assembly 10 after colliding with the inner bottom surface 22 of the container body 2 has the convex portion 100 or the container body 2. Bounces upward at the inner bottom surface 22 and an external force is applied upward in the longitudinal direction, and the upper end (nozzle 13) collides with the primary lid 41 this time. At this time, the fuel assembly 10 corresponding to the position of the convex portion 100 collides with the primary lid 41 while being rebounded upward by the elastic force of the convex portion 100.

  In the fuel assembly storage container 1 of the fifth embodiment, the convex portion 100 is configured by a buffer member made of an elastic material having a different Young's modulus. For this reason, when each of the stored fuel assemblies 10 is applied with an external force in the longitudinal direction, the inner bottom surface 22 of the container body 2 or the primary lid depending on the Young's modulus of the load distribution means (convex portion 100). The load of the fuel assembly 10 acting on the inner wall surface 41a of 41 is dispersed in a plurality. That is, the time until the load of the fuel assembly 10 is applied to the inner bottom surface 22 of the container body 2 or the inner wall surface 41a of the primary lid 41 is dispersed into a plurality of times.

  As a result, the generation time of stress in the lid member 4 and the container body 2 due to the load of the fuel assembly 10 is dispersed, and the peak thereof is smaller than that of a conventional fuel assembly storage container having no load distribution means. As a result, the stress generated in the lid member 4 and the container body 2 can be relaxed.

  In the fifth embodiment described above, the convex portion 100 of the load distribution means is provided on the inner bottom surface 22 of the container body 2, but this is not restrictive. Although not clearly shown in the drawing, for example, the load distribution means is a portion of the fuel assembly 10 (nozzle 13), a portion of the inner bottom surface 22 of the container body 2 facing the end of the fuel assembly 10, or a lid member. The end of the fuel assembly 10 on the four inner wall surfaces 41a may be provided in at least one selected portion of the facing portions. In addition, for example, the load distribution means includes an end portion (nozzle 13) of the fuel assembly 10, a portion of the inner bottom surface 22 of the container body 2 facing the end portion of the fuel assembly 10, and an inner wall surface 41 a of the lid member 4. The part which the edge part of the fuel assembly 10 opposes in this may be provided in the form which combined selectively.

  Moreover, you may apply the convex part 100 of the load distribution means in this Embodiment 5 to the convex part 100 of Embodiment 1 mentioned above.

  In the fifth embodiment, the load of the fuel assembly 10 is applied to the inner bottom surface 22 of the container body 2 or the inner wall surface 41a of the primary lid 41 due to the difference in Young's modulus of the load dispersing means (convex portion 100). Disperse the time until. For this reason, the distance h between the inner bottom surface 22 of the container body 2 and the inner wall surface 41a of the primary lid 41 and the end (nozzle 13) may be set to 0, and the above-described effects can be obtained.

  In the fifth embodiment described above, the operation and effect of the state in which the fuel assembly storage container 1 drops vertically from the bottom of the container body 2 has been described, but this is not restrictive. For example, even if each fuel assembly 10 stored in a state where the fuel assembly storage container 1 is placed horizontally is applied with an external force in the longitudinal direction (horizontal direction), the load distribution means ( By the convex portion 100), the time until the load of the fuel assembly 10 is applied to the inner bottom surface 22 of the container body 2 or the inner wall surface 41a of the primary lid 41 can be divided into a plurality of times. As a result, the generation time of stress in the lid member 4 and the container body 2 due to the load of the fuel assembly 10 is dispersed, and the peak thereof is smaller than that of a conventional fuel assembly storage container having no load distribution means. As a result, the stress generated in the lid member 4 and the container body 2 can be relaxed.

  As described above, the fuel assembly storage container according to the present invention is suitable for alleviating the stress generated in the lid member and the container body due to the load of the moved fuel assembly.

DESCRIPTION OF SYMBOLS 1 Fuel assembly storage container 2 Container main body 20 Container main body space 21 Opening part 22 Inner bottom surface 3 Neutron shield 4 Lid member 41 Primary lid 41a Inner wall surface 42 Secondary lid 5 Basket 50 Square pipe 51 Cell 6 Spacer 10 Fuel assembly DESCRIPTION OF SYMBOLS 11 Fuel rod 12 Supporting grid 13 Nozzle 100 Convex part G Fixed surface h The space | interval between the inner bottom face of a container main body and the inner wall face of a primary lid, and the edge part of a fuel assembly H The protrusion dimension of a convex part L The length dimension of a fuel assembly

Claims (1)

And bottomed container body top is opened, and a lid member closing the opening, the fuel assembly, the longitudinal end portion on the inner wall surface of the inner bottom surface and said lid member of said container body In the fuel assembly storage container that stores a plurality of
Load distribution means for dividing the load of the fuel assembly acting on the inner bottom surface of the container main body or the inner wall surface of the lid member into a plurality of parts when an external force is applied to each fuel assembly in the longitudinal direction; Yes, and
The load distribution means includes an end of the fuel assembly, a portion of the inner bottom surface of the container body facing the end of the fuel assembly, or an end of the fuel assembly on the inner wall surface of the lid member. A buffer member having a different Young's modulus is provided on at least one of the facing parts, and the buffer member having a different Young's modulus includes the inner bottom surface of the container body and the inner wall surface of the lid member, A fuel assembly storage container characterized by being formed at the same distance from the end of the fuel assembly.

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