JP5398279B2 - Cushioning member for fuel rod assembly and transport container - Google Patents

Description

  The present invention relates to a shock absorber for a fuel rod assembly that reduces the impact received by the fuel rods constituting the fuel rod assembly, and a transport container.

  When transporting the fuel rod assembly, the fuel rod assembly is stored in a transport container and transported. Here, the transport container may be lifted by a crane. Transport containers are transported with great care so that they do not fall, and even today, sufficient safety is ensured for transport of fuel rod assemblies. However, in order to transport the fuel rod assembly more safely, it is necessary to assume that the transport container falls.

  For example, Patent Literature 1 discloses a technique including a metal bent lattice plate for elastic contact that is fitted and contacted between fuel rods as a technique for reducing damage to a fuel rod assembly due to vibration during transportation. Has been.

JP 2004-117187 A

  In a fuel rod assembly for a pressurized water reactor, the fuel rods are supported by a grid. Here, the fuel rod is supported by the grid by the frictional force between the side periphery of the fuel rod and the grid. Therefore, when the fuel rod receives a force larger than the frictional force in the axial direction of the fuel rod, the fuel rod moves in the axial direction.

  For example, assuming that the transport container has fallen, the impact when the transport container collides with the ground is also transmitted to the fuel rod assembly stored in the transport container. Thereby, it is necessary to assume that the fuel rod may move in the axial direction with respect to the grid in some cases.

  Here, in the fuel rod assembly, the nozzle is disposed so as to face the end portion of the fuel rod in the axial direction. A gap is formed between the nozzle and the end of the fuel rod. Therefore, when the fuel rod moves in the axial direction, the end of the fuel rod may collide with the nozzle.

  However, the elastic metal bent lattice plate disclosed in Patent Document 1 cannot restrict the movement of the fuel rod in the axial direction. If the end of the fuel rod collides with the nozzle, the fuel rod The impact received cannot be reduced.

  The present invention has been made in view of the above, and an object thereof is to reduce the impact received by the fuel rod.

  In order to solve the above-described problems and achieve the object, a buffer member for a fuel rod assembly according to the present invention has an axial gap between the end of the fuel rod and the end of the fuel rod. And a nozzle disposed opposite to each other in the axial direction of the fuel rod, and a radial gap between the nozzle and the side peripheral portion, each central axis being in the axial direction A fuel rod assembly cushioning member attached to a fuel rod assembly comprising a plurality of guide tubes provided along the radial direction gaps, in a direction perpendicular to the central axis. It is characterized in that at least a part is inserted and disposed in the axial gap.

  In order to solve the above-described problems and achieve the object, a transport container according to the present invention stores a storage portion for storing a fuel rod assembly to which a buffer member for a fuel rod assembly is attached, and stores the storage portion. A fuel container, wherein the fuel rod assembly has an axial gap between the end of the fuel rod and the end of the fuel rod and the shaft of the fuel rod. A plurality of nozzles arranged opposite to each other in a direction and connected to the nozzles, and having radial gaps between the respective side peripheral portions, each center axis being provided along the axial direction. The fuel rod assembly buffer member is disposed in the axial gap, with at least a portion thereof being inserted into the radial gap in a direction perpendicular to the central axis. It is characterized by that.

  As described above, the fuel rod assembly cushioning member according to the present invention is attached to the axial clearance of the fuel rod assembly. As a result, even if the transport container for storing the fuel rod assembly is dropped, the fuel rod whose end faces the shock absorber for the fuel rod assembly in the axial direction does not directly collide with the nozzle, A fuel rod assembly buffer member is interposed between the nozzle and the end of the fuel rod assembly buffer member. Therefore, the shock absorber for the fuel rod assembly can reduce the impact transmitted to the fuel rod.

  Furthermore, the fuel rod whose end is opposed to the fuel rod assembly buffer member in the axial direction has a greater thickness than the case where the fuel rod assembly buffer member is not provided in the axial clearance. Therefore, the distance that can be moved in the axial direction is reduced. Therefore, even if the fuel rod moves in the axial direction during transportation, the fuel rod assembly buffer member has an axial movement distance of the fuel rod whose end portion faces the fuel rod assembly buffer member in the axial direction. Can be reduced.

  As a preferred aspect of the present invention, a plurality of first-direction bar-shaped buffer portions formed in a first direction orthogonal to the central axis and inserted into the radial gap, the central axis and the first axis A plurality of first-direction bar-shaped buffer portions that are connected to a portion on the guide tube side at intervals equal to or greater than the diameter of the guide tube in a second direction orthogonal to the direction; It is desirable to be configured to include.

  With the above-described configuration, the shock absorber for a fuel rod assembly according to the present invention is configured such that, even if the transport container falls, the first impact received by the fuel rod whose end portion faces the radial gap is received among the plurality of fuel rods. The first direction coupling buffer part absorbs the shock received by the direction coupling buffer part and the other fuel rod receives. Thereby, the buffer member for a fuel rod assembly according to the present invention can reduce the impact received by the fuel rod.

  As a preferred aspect of the present invention, it is desirable that a plurality of the first-direction bar-shaped buffer portions are disposed in the axial gap.

  For example, when the fuel rod assembly is a recycled fuel rod assembly, the size of the axial gap may vary. In this case, the fuel rod assembly cushioning member according to the present invention has a plurality of first-direction rod-shaped cushioning portions arranged in the axial gap, so that the gap between the end of the fuel rod and the nozzle is the first. It can be filled with a directional bar. Thereby, the buffer member for a fuel rod assembly according to the present invention can reduce the movement distance of the fuel rod in the axial direction.

  As a preferable aspect of the present invention, a plurality of second-direction bar-shaped buffer portions that are formed toward the second direction and are inserted into the radial gap, and a diameter greater than or equal to the diameter of the guide tube in the first direction. It is desirable that the plurality of second-direction bar-shaped buffer portions are spaced apart from each other and include a second-direction connecting buffer portion connected to the guide tube side portion.

  With the above configuration, the fuel rod assembly cushioning member according to the present invention has more fuel rods than the case where only the first-direction rod-shaped cushioning portion and the first-direction coupling cushioning portion are attached to the axial clearance. The impact received by the fuel rod can be reduced.

  As a preferred aspect of the present invention, it is desirable that a plurality of the second direction bar-shaped buffer portions are disposed in the axial gap.

  When there is variation in the size of the axial gap, the fuel rod assembly cushioning member according to the present invention has a plurality of second-direction rod-shaped cushioning portions arranged in the axial gap, so that the end of the fuel rod The gap between the nozzle and the nozzle can be filled with the second-direction bar-shaped buffer portion. Thereby, the buffer member for a fuel rod assembly according to the present invention can reduce the movement distance of the fuel rod in the axial direction.

  As a preferred aspect of the present invention, it is desirable that the first-direction bar-shaped buffer portions and the second-direction bar-shaped buffer portions are alternately arranged in the axial gap.

  When a plurality of first-direction bar-shaped buffer portions and a plurality of second-direction bar-shaped buffer portions are arranged in the axial gap, the arrangement may be performed in the axial direction of the fuel rod, for example, a first-direction bar-shaped buffer portion. The order of the first direction bar-shaped buffer part, the second direction bar-shaped buffer part, and the second direction bar-shaped buffer part can be considered. However, in the buffer member for a fuel rod assembly according to the present invention, the first-direction bar-shaped buffer portion and the second-direction bar-shaped buffer portion are alternately arranged in the axial gap, rather than such an arrangement. Is preferred. The reason will be described below.

  For example, when the second direction rod-shaped buffer portion is disposed closer to the fuel rod than the first direction rod-shaped buffer portion in the axial direction of the fuel rod, the end portion is pivoted only on the first direction rod-shaped buffer portion. The fuel rods that face each other in the direction move in the axial direction until the end portions thereof come into contact with the first-direction rod-shaped buffer portion.

  Here, when the first-direction bar-shaped buffer portion and the second-direction bar-shaped buffer portion are alternately arranged in the axial gap, the second-direction bar-shaped buffer portion does not overlap in the axial direction. The distance between the end portion of the fuel rod and the first-direction rod-shaped buffer portion is reduced. Thereby, the buffer member for a fuel rod assembly according to the present invention can reduce the movement distance of the fuel rod in the axial direction.

  In a preferred aspect of the present invention, the first direction is the virtual plane with respect to one side of a cross section obtained by cutting a quadrangular prism formed by bundling a plurality of the fuel rods along a virtual plane orthogonal to the central axis. It is desirable that the direction be inclined upward.

  With the above configuration, the fuel rod assembly buffer member according to the present invention has a surface orthogonal to the guide tube among the surfaces of the fuel rod assembly buffer member, as compared with the case where the first direction is parallel to the one side. The area of becomes larger. Therefore, the shock absorber for the fuel rod assembly according to the present invention can reduce the impact received by the fuel rods with more fuel rods than when the first direction is parallel to the one side.

  As a preferred aspect of the present invention, a plurality of storages are stored in the storage space formed in the first-direction bar-shaped buffer portion so as to be movable in the second direction and arranged in the first direction. A projecting cushioning member having a dimension in the first direction less than a size of the radial gap formed between each side peripheral portion of the guide tube, and the projecting cushioning member in the second direction. And a pressing force applying means that applies a force toward the head.

  With the above configuration, the fuel rod assembly cushioning member according to the present invention includes the side periphery of each of the plurality of guide tubes arranged in the first direction as the protruding cushioning member moves in the second direction. A protruding cushioning member is disposed in the radial gap formed between the two.

  As a result, the shock received by the fuel rods whose end portions are opposed in the axial direction are projected and buffered in the radial gaps formed between the side peripheral portions of the plurality of guide tubes arranged in the first direction. The member absorbs. Therefore, the shock absorber for the fuel rod assembly according to the present invention can reduce the impact received by the fuel rod.

  The present invention can reduce the impact received by the fuel rod.

FIG. 1 is a perspective view showing a cask. FIG. 2 is a configuration diagram showing the fuel rod assembly. FIG. 3 is a perspective view showing a transport container for a new fuel rod. FIG. 4 is a perspective view showing another transport aircraft. FIG. 5 is a projection view in which the fuel rod assembly is projected in a direction orthogonal to the central axis of the fuel rod. FIG. 6 is a cross-sectional view of the fuel rod assembly cut along a plane perpendicular to the central axis of the fuel rod. FIG. 7 is a projected view of the fuel rod assembly cushioning member of the first embodiment attached to the fuel rod assembly in the axial direction. FIG. 8 is a projected view in the axial direction of the fuel rod assembly cushioning member of the second embodiment attached to the fuel rod assembly. FIG. 9 is a projection view in the axial direction of the fuel rod assembly cushioning member of Embodiment 3 attached to the fuel rod assembly. FIG. 10 is a projected view of the fuel rod assembly cushioning member of the fourth embodiment attached to the fuel rod assembly in the axial direction. FIG. 11 is a projection view in the axial direction of the fuel rod assembly cushioning member of Embodiment 5 attached to the fuel rod assembly. FIG. 12 is a cross-sectional view showing the cam mechanism cut along a virtual plane orthogonal to the central axis of the control rod guide tube. FIG. 13 is a cross-sectional view of the imaginary plane parallel to the central axis of the control rod guide tube, with the cam mechanism cut. FIG. 14 is a cross-sectional view showing the cam mechanism in a state in which the protruding buffer member protrudes from the storage space, cut along an imaginary plane parallel to the central axis of the control rod guide tube. FIG. 15 is a cross-sectional view showing the spring push-out mechanism cut along a virtual plane orthogonal to the central axis of the control rod guide tube.

  Hereinafter, embodiments of a buffer member for a fuel rod assembly and a transport container according to the present invention will be described in detail with reference to the drawings. In addition, this invention is not limited by this embodiment.

(Embodiment 1)
FIG. 1 is a perspective view showing a cask. FIG. 2 is a configuration diagram showing the fuel rod assembly. A cask 900 shown in FIG. 1 is one of transport containers for storing the fuel rod assembly 800 shown in FIG. 2, and is a container for storing recycled fuel. The cask 900 shown in FIG. 1 includes a trunk main body 910 as a main body portion, a bottom portion 920, a lid portion 930, and a basket 940 as a storage portion.

  The trunk body 910 is formed in a cylindrical shape. The bottom 920 is provided without a gap at one end of the trunk body 910. The lid portion 930 is attached to the other end portion of the trunk body 910 without any gap. The basket 940 is provided in a space surrounded by the trunk body 910, the bottom portion 920, and the lid portion 930. The basket 940 includes a plurality of cells 941. In the cask 900, the fuel rod assembly 800 shown in FIG.

  FIG. 3 is a perspective view showing a transport container for a new fuel rod. FIG. 4 is a perspective view showing another transport aircraft. Here, the transport container for storing the fuel rod assembly 800 is not limited to the cask 900 shown in FIG.

  For example, a transport container 980 shown in FIG. 3 is one of transport containers for storing a new fuel rod assembly that is a fuel rod assembly 800 to be used in the future. The transport container 980 includes a container main body 981 and a lid 982. The transport container 980 is provided with a storage portion 983 in a space surrounded by a container main body 981 as a main body portion and a lid body 982, and a new fuel rod assembly is stored inside the storage portion 983.

  Also, the transport container 990 shown in FIG. 4 is another container that stores the fuel rod assembly 800. The transport container 990 includes a base 991 serving as a main body and a box-shaped lid 992. The transport container 990 is provided with a storage portion 993 in a space surrounded by the base 991 and the lid 992, and the fuel rod assembly 800 is stored inside the storage portion 993.

  FIG. 5 is a projection view in which the fuel rod assembly is projected in a direction orthogonal to the central axis of the fuel rod. FIG. 6 is a cross-sectional view of the fuel rod assembly cut along a plane perpendicular to the central axis of the fuel rod. A fuel rod assembly 800 shown in FIGS. 2, 5, and 6 is, for example, a fuel rod assembly for a pressurized water reactor. The fuel rod assembly 800 includes a fuel rod 801 and a grid 810, as shown in FIGS.

  In the fuel rod assembly 800, a plurality of fuel rods 801 are arranged side by side in, for example, a first direction and a second direction. Here, in this embodiment, when the fuel rod assembly 800 is cut by a virtual plane orthogonal to the central axis, the fuel rod assembly 800 is substantially composed of a fuel rod group 802 composed of a plurality of fuel rods 801. Formed into a square. That is, in the fuel rod assembly 800 of this embodiment, the rows and columns of the fuel rod group 802 are orthogonal to each other.

  However, in the fuel rod assembly, when the fuel rod assembly is cut in a virtual plane orthogonal to the central axis, the fuel rod group 802 composed of a plurality of fuel rods 801 may be formed in a diamond shape, for example. Conceivable. In this case, in the fuel rod assembly, the rows and columns of the fuel rod group 802 are not orthogonal. In the case of such a fuel rod assembly, the first direction and the second direction intersect with each other without being orthogonal.

  As shown in FIG. 6, the fuel rod assembly 800 includes a plurality of fuel rods 801 arranged in the first direction and the second direction. The grid 810 bundles and supports a plurality of fuel rods 801. Specifically, the grid 810 is formed in a lattice shape by forming a plurality of holes penetrating in the axial direction in a plate-like member.

  The grid 810 supports the plurality of fuel rods 801 by inserting the fuel rods 801 into the plurality of holes, respectively. At this time, a gap is formed between the side peripheral portions of the adjacent fuel rods 801. The grid 810 supports the fuel rod 801 by a frictional force between the inner peripheral surface of the hole and the side peripheral portion of the fuel rod 801.

  As shown in FIGS. 5 and 6, the fuel rod assembly 800 further includes a control rod guide tube 803 a, a plurality of instrumentation guide tubes 803 b, and a nozzle 850. The control rod guide tube 803a and the instrumentation guide tube 803b are cylindrical members. Hereinafter, when the control rod guide tube 803a and the instrumentation guide tube 803b are not distinguished, the control rod guide tube 803a and the instrumentation guide tube 803b are collectively referred to as a guide tube 803.

  The guide tube 803 is arranged in the fuel rod group 802 as shown in FIG. Each guide tube 803 is provided with a central axis parallel to the central axis of the fuel rod 801. When the fuel rod group 802 shown in FIG. 5 is viewed as one quadrangular column, the control rod guide tube 803a is a center of a cross section obtained by cutting the quadrangular column by a virtual plane VF01 orthogonal to the central axis of the control rod guide tube 803a. Placed in.

  The instrumentation guide tube 803b is disposed with a gap between it and the side periphery of the control rod guide tube 803a. In addition, the plurality of instrumentation guide tubes 803b are also arranged with a gap between each side peripheral portion. As a result, as shown in FIG. 5, when the fuel rod assembly 800 is projected in a direction orthogonal to the central axis of the control rod guide tube 803a, the fuel rod assembly 800 is in contact with each side peripheral portion of the guide tube 803. A gap is formed between them. Hereinafter, the gap is referred to as a radial gap RS.

  As shown in FIGS. 2 and 5, the nozzle 850 includes a first nozzle 851 and a second nozzle 852. Here, as for the nozzle 850, the 1st nozzle 851 is arrange | positioned at the bottom part 920 side shown in FIG. 1, and the 2nd nozzle 852 is arrange | positioned at the cover part 930 side. The cask 900 is usually transported with the bottom portion 920 disposed on the lower side in the vertical direction.

  When the fuel rod assembly 800 is transported, the first nozzle 851 is usually arranged on the lower side in the vertical direction. That is, in the nozzle 850, the first nozzle 851 is a so-called lower nozzle, and the second nozzle 852 is a so-called upper nozzle.

  The first nozzle 851 is connected to one end of each guide tube 803. The second nozzle 852 is connected to the other end of the guide tube 803. Thus, in the fuel rod assembly 800, the first nozzle 851 is arranged on one end side of the fuel rod 801, and the second nozzle 852 is arranged on the other end side of the fuel rod 801.

  A plurality of grids 810 are arranged at intervals in the axial direction. The grid 810 is connected to the guide tube 803. As described above, the fuel rod assembly 800 includes a plurality of fuel rods 801 bundled by a plurality of grids 810 supported by the guide tube 803 between the first nozzle 851 and the second nozzle 852. It is supported side by side in the second direction.

  Here, as shown in FIG. 5, an axial gap is formed between the end of the fuel rod 801 and the nozzle 850. Hereinafter, the gap is referred to as an axial gap AS. In the axial clearance AS, the guide tube 803 is not covered with the fuel rod group 802 and is exposed from the fuel rod group 802.

  Here, as described above, the fuel rod 801 is supported by the grid 810 by the frictional force between the side periphery of the fuel rod 801 and the grid 810. Therefore, in order to transport the fuel rod assembly 800 more safely, the fuel rod assembly 800 may be subjected to vibration during transportation of the fuel rod assembly 800 or an impact when the cask 900 storing the fuel rod assembly 800 is dropped. It is necessary to assume a case where 801 moves in the axial direction with respect to the grid 810.

  When the fuel rod 801 moves in the axial direction, the end of the fuel rod 801 may collide with the nozzle 850. Assuming that the fuel rod 801 may be damaged by the impact at this time, the fuel rod assembly 800 is a fuel rod assembly cushioning member for reducing the impact received by the fuel rod 801 during transportation. Is attached and stored in the cask 900. Below, the structure of the buffer member for fuel rod assemblies will be described.

  FIG. 7 is a projected view of the fuel rod assembly cushioning member of the first embodiment attached to the fuel rod assembly in the axial direction. The fuel rod assembly buffer member 100 includes an axial gap AS between the first nozzle 851 and one end of the fuel rod 801 shown in FIG. 5, and the second nozzle 852 and the other end of the fuel rod 801. The fuel rod assembly 800 is attached to both the axial gap AS and the fuel rod assembly 800.

  These two fuel rod assembly cushioning members 100 have the same configuration, and the procedure for attaching them to the fuel rod assembly 800 is also the same. Of the axial gap AS between the first nozzle 851 and one end of the fuel rod 801 and the axial gap AS between the second nozzle 852 and the other end of the fuel rod 801 Even if the fuel rod assembly buffer member 100 is attached to one of the axial gaps AS, the fuel rod 801 moves in the direction where the fuel rod assembly buffer member 100 is provided. The rod assembly buffer member 100 can reduce the impact received by the fuel rod 801.

  However, assuming that the fuel rod 801 moves in two of the axial directions, the fuel rod assembly buffer member 100 has a shaft between the first nozzle 851 and one end of the fuel rod 801. It is preferable to be attached to both the directional gap AS and the axial gap AS between the second nozzle 852 and the other end of the fuel rod 801. Thereby, the shock absorber 100 for the fuel rod assembly can reduce the impact received by the fuel rod 801 regardless of which of the two axial directions the fuel rod 801 moves.

  The fuel rod assembly cushioning member 100 is, for example, wood, a metal member having a honeycomb structure, or a foam metal. The axial dimension of the fuel rod assembly buffer member 100, that is, the thickness of the fuel rod assembly buffer member 100 is formed to be equal to or smaller than the axial clearance AS.

  The difference between the thickness of the fuel rod assembly buffer member 100 and the size of the axial clearance AS is also the distance that the fuel rod assembly buffer member 100 can move in the axial direction. Therefore, the smaller the difference between the thickness of the fuel rod assembly buffer member 100 and the size of the axial gap AS, the better. Thereby, even if the fuel rod 801 moves in the axial direction, the fuel rod assembly buffer member 100 can reduce the amount of movement of the fuel rod 801 in the axial direction.

  As shown in FIG. 7, the fuel rod assembly cushioning member 100 is divided into an upper member 110 and a second member 130. The fuel rod assembly buffer member 100 is configured, for example, by being divided into an upper member 110 and a second member 130 on a virtual plane VF02 including the central axis of the control rod guide tube 803a. The virtual plane VF02 is, for example, a plane orthogonal to a virtual straight line along the first direction.

  The upper member 110 and the second member 130 are formed in the same manner. Therefore, in the following description, the upper member 110 will be mainly described. The upper member 110 includes a bar-shaped buffer portion 111 as a first-direction bar-shaped buffer portion and a connection buffer portion 115 as a first-direction connection buffer portion. The rod-shaped buffer part 111 is formed in, for example, a quadrangular column or a cylinder. The rod-shaped buffer portion 111 is provided with a central axis along the first direction.

  In the case of a quadrangular prism, depending on the ratio of the length of the side in the axial direction to the length of the side in the second direction, it may look like a plate. The rod-shaped buffer portion 111 includes a configuration in which the length of the side in the second direction is relatively large with respect to the length of the side in the axial direction.

  A plurality of rod-shaped buffer portions 111 are provided side by side in the second direction. Here, the respective rod-shaped buffer portions 111 are arranged at intervals equal to or larger than the diameters of the control rod guide tube 803a and the instrumentation guide tube 803b. In other words, the distance between the side wall surface 112 of the bar-shaped buffer portion 111 and the side wall surface facing the side wall surface 112 of the two side wall surfaces of the adjacent bar-shaped buffer portions is the control rod guide tube 803a and the instrumentation guide tube 803b. More than the diameter.

  In addition, the dimension in the second direction, that is, the width of the rod-shaped buffer portion 111 is equal to or less than the distance between each side peripheral portion when the control rod guide tube 803a and the instrumentation guide tube 803b are projected in the first direction. It is formed. Thereby, the rod-shaped buffer part 111 can be inserted in the radial direction gap RS toward the first direction.

  Here, the larger the area of the plane perpendicular to the control rod guide tube 803a, the greater the number of fuel rods 801 whose end portions are opposed to the fuel rod assembly buffer member 100 in the axial direction. Therefore, the rod-shaped buffer portion 111 is more preferable as the width is larger.

  The rod-shaped buffer portion 111 is connected at one end thereof to the surface on the virtual plane VF02 side of the connection buffer portion 115 at the root side end portion 113. In the rod-shaped buffer portion 111, the tip end portion 114 which is the other end portion is inserted into the radial clearance RS toward the virtual plane VF02. Thereby, the rod-shaped buffer part 111 is inserted from the radial gap RS and attached to the axial gap AS.

  Here, the plurality of rod-shaped buffer portions 111 are not limited to the configuration in which each of the rod-shaped buffer portions 111 is connected to the connection buffer portion 115. The plurality of rod-shaped buffer portions 111 may be inserted into the radial gap RS separately without being connected to the connection buffer portion 115. Even in this case, the fuel rod assembly cushioning member 100 can reduce the impact received by the fuel rod 801 whose end faces the rod-shaped cushioning portion 111 in the axial direction.

  However, in the buffer member 100 for the fuel rod assembly, the plurality of rod-shaped buffer portions 111 are connected to the connection buffer portion 115, respectively, and the rod-shaped buffer portions 111 are integrally inserted into the plurality of radial gaps RS at once. Is preferred. In this case, it is possible to reduce the time and labor required for arranging the rod-shaped buffer portions 111 in the axial gap AS, as compared to the case where the plurality of rod-shaped buffer portions 111 are individually inserted into the plurality of radial gaps RS.

  Here, in the fuel rod assembly 800, a space surrounded by a plurality of instrumentation guide tubes 803b is formed around the control rod guide tube 803a. The connection buffer 115 is disposed outside the space. Specifically, the connection buffer part 115 includes a base part 116 and two side parts 117.

  The base 116 is formed toward the second direction. The side part 117 is formed toward the first direction. As for the side part 117, one edge part is connected with the both ends of the 1st direction of the base part 116, and the front-end | tip part 118 which is the other edge part is arrange | positioned at the virtual plane VF02 side. Constructed in this way, the coupling buffer 115 is provided so as to surround the guide tube 803 with the base 116 and the two side portions 117.

  Here, in the fuel rod assembly shock-absorbing member 100, for example, it is preferable that the front end portion 118 of the upper member 110 and the front end portion 138 of the side portion 137 of the end member 130 are connected so as to be detachable from each other. In this case, the front end portion 118 and the front end portion 138 are connected to each other by, for example, a hook-and-loop fastener or a fitting portion attached thereto.

  Moreover, it is preferable that the front-end | tip part 114 of the upper member 110 and the front-end | tip part 134 of the rod-shaped buffer part 131 of the end member 130 may be connected mutually. In this case, the front end portion 114 and the front end portion 134 are connected to each other by, for example, a hook-and-loop fastener or a fitting portion attached thereto.

  In this manner, the upper member 110 and the member 130 are connected so as to be detachable from each other, whereby the fuel rod assembly cushioning member 100 is connected to the member 110 and the member 130 during transportation. The possibility of dropping from the aggregate 800 can be suppressed.

  Thus, the fuel rod assembly buffer member 100 is attached to the axial clearance AS of the fuel rod assembly 800. Thus, the fuel rod 801 whose end portion faces the fuel rod assembly buffer member 100 in the axial direction is more fuel rod assembly than the case where the fuel rod assembly buffer member 100 is not provided in the axial gap AS. The distance that can be moved in the axial direction is reduced by the thickness of the buffer member 100 for use.

  Therefore, even if the fuel rod 801 moves in the axial direction during transportation, the fuel rod assembly buffer member 100 has an end portion facing the fuel rod assembly buffer member 100 in the axial direction. The moving distance in the direction can be reduced.

  Further, even when the cask 900 storing the fuel rod assembly 800 falls, the fuel rod 801 whose end portion faces the fuel rod assembly cushioning member 100 in the axial direction directly collides with the nozzle 850. Instead, the fuel rod assembly cushioning member 100 is interposed between the nozzle 850 and the end of the fuel rod assembly cushioning member 100. Thereby, the shock absorber 100 for the fuel rod assembly can reduce the impact transmitted to the fuel rod 801.

  Here, a fuel rod assembly 800 shown in FIG. 7 schematically shows a fuel rod assembly actually used in a nuclear power plant. Hereinafter, a specific arrangement of the guide tube 803 will be described.

  Here, in order to describe a specific arrangement of the guide tube 803, one of the four corners of the fuel rod group 802 is set as a coordinate (1, 1) as a reference coordinate. Coordinates that are 16 distances from the reference coordinates in the first direction are coordinates (17, 1), and coordinates that are 16 distances from the reference coordinates in the second direction are coordinates (1, 17). In addition, the coordinates farthest from the reference coordinates, that is, the coordinates that are diagonal to the reference coordinates are defined as coordinates (17, 17).

The control rod guide tube 803a is arranged at the coordinates (9, 9). The instrumentation guide tube 803b
Coordinates (3, 6), coordinates (3, 9), coordinates (3, 12), coordinates (4, 4), coordinates (4, 14), coordinates (6, 3), coordinates ( 6, 6), coordinates (6, 9), coordinates (6, 12), coordinates (6, 15), coordinates (9, 3), coordinates (9, 6), coordinates (9, 12), coordinates (9, 15), coordinates (12, 3), coordinates (12, 6), coordinates (12, 9), coordinates (12, 12), coordinates (12, 15) And coordinates (14, 4), coordinates (14, 14), coordinates (15, 6), coordinates (15, 9), and coordinates (15, 12). A total of 24 are provided.

  One fuel rod 801 is disposed at each of the other coordinates, and a total of 264 fuel rods are provided. Here, as an example of a configuration in which the fuel rod assembly buffer member 100 is attached to the fuel rod assembly 800, coordinates where the rod-shaped buffer portion 111 of the upper member 110 is disposed will be described.

  In the fuel rod assembly cushioning member 100, one base side end 113 of the plurality of rod-shaped cushioning portions 111 is arranged at the coordinates (3, 5), and the tip 114 is arranged at the coordinates (3, 9). Is done. Further, in the fuel rod assembly buffer member 100, the base side end portion 113 of another rod-shaped buffer portion 111 is arranged at coordinates (3, 7) and coordinates (3, 8), and the tip end portion 114 is coordinate (9, 7) and coordinates (9, 8).

  The fuel rod assembly cushioning member 100 has a base end portion 113 of another rod-shaped cushioning portion 111 arranged at coordinates (3, 10) and coordinates (3, 11), and a tip end portion 114 at coordinates (9, 10) and coordinates (9, 11). Further, in the buffer member 200 for the fuel rod assembly, the base side end portion 113 of another rod-shaped buffer portion 111 is arranged at the coordinates (3, 13), and the tip end portion 114 is arranged at the coordinates (9, 13). The bar-shaped buffer part 131 of the second member 130 is arranged symmetrically with the bar-shaped buffer part 111 with respect to the virtual plane VF02.

  When the fuel rod assembly cushioning member 100 having the above-described configuration is attached to the fuel rod assembly 800 having the above-described configuration, a maximum of 214 of the 264 fuel rods 801 are located at positions facing the respective end portions. The fuel rod assembly cushioning member 100 is arranged.

  That is, when attached to the fuel rod assembly 800 having the above-described configuration, the fuel rod assembly cushioning member 100 can reduce the movement amount in the axial direction of 81% of the fuel rods 801 at the maximum and 81 in the whole. % Of the fuel rods 801 can reduce the impact of the fuel rods.

  Here, in the present embodiment, the upper member 110 and the second member 130 are described as being attached to the axial gap AS one by one. However, the upper member 110 and the second member 130 are axially disposed in the axial gap AS. A plurality of each may be attached.

  For example, when the thickness in the axial direction of the upper member 110 and the second member 130 is less than the size of the axial clearance AS, the upper member 110 and the second member 130 are added to the axial clearance AS and attached. Thus, the fuel rod assembly buffer member 100 can fill the gap between the end of the fuel rod 801 and the nozzle 850 with the upper member 110 and the second member 130. As a result, the fuel rod assembly buffer member 100 can reduce the axial movement distance of the fuel rod 801.

(Embodiment 2)
FIG. 8 is a projected view in the axial direction of the fuel rod assembly cushioning member of the second embodiment attached to the fuel rod assembly. The fuel rod assembly buffer member 200 of the second embodiment is further characterized in that it includes a second direction buffer member 210.

  The second direction buffer member 210 includes a bar-shaped buffer portion 211 as a second-direction bar-shaped buffer portion and a connection buffer portion 215 as a second-direction connection portion buffer portion. The rod-shaped buffer part 211 is provided along the second direction. A plurality of rod-shaped buffer portions 211 are provided side by side in the first direction.

  Here, the respective bar-shaped buffer portions 211 are arranged with an interval equal to or larger than the diameter of the guide tube 803. That is, the distance between the side wall surface of the rod-shaped buffer portion 211 and the side wall surface facing the above-described side wall surface of the two side wall surfaces of the adjacent bar-shaped buffer portions is equal to or greater than the diameter of the guide tube 803.

  In addition, the dimension in the first direction, that is, the width of the rod-shaped buffer portion 211 is formed to be equal to or less than the distance from each side peripheral portion when the guide tube 803 is projected in the second direction. Thereby, the rod-shaped buffer part 211 can be inserted in the radial direction gap RS in the second direction.

  Here, the larger the area of the plane perpendicular to the control rod guide tube 803a, the greater the number of the fuel rods 801 whose end portions are opposed to the fuel rod assembly buffer member 100 in the axial direction. Therefore, the rod-shaped buffer portion 211 is more preferable as the width is larger.

  The rod-shaped buffer portion 211 has a base-side end portion 212 that is one end portion connected to a portion of the connection buffer portion 215 on the control rod guide tube 803a side. In the rod-shaped buffer portion 211, the tip end portion 213 which is the other end portion is inserted into the radial gap RS in the second direction. Thereby, the rod-shaped buffer part 211 is inserted from the radial gap RS and attached to the axial gap AS.

  Here, the plurality of rod-shaped buffer portions 211 are not limited to the configuration in which each is coupled to the coupling buffer portion 215. The plurality of bar-shaped buffer portions 211 may be inserted into the radial gap RS separately without being connected to the connection buffer portion 215. Even in this case, the shock absorber 100 for the fuel rod assembly can reduce the impact received by the fuel rod 801 that faces the rod-shaped buffer portion 211 in the axial direction.

  However, in the buffer member 100 for the fuel rod assembly, the plurality of rod-shaped buffer portions 211 are connected to the connection buffer portion 215, respectively, and the rod-shaped buffer portions 211 are integrally inserted into the plurality of radial gaps RS at once. Is preferred. In this case, it is possible to reduce the time and labor required for arranging the bar-shaped buffer portions 211 in the axial gap AS, compared to the case where the plurality of bar-shaped buffer portions 211 are individually inserted into the plurality of radial gaps RS.

  The buffer member 210 for the second direction may be made of wood, a metal member having a honeycomb structure, or a foam metal. For example, the second direction buffer member 210 is made of a thin metal plate that is thinner than the upper member 110 and the end member 130. May be. However, when the second direction buffer member 210 is formed of a thin plate, the second direction buffer member 210 is not between the upper member 110 and the second member 130 and the nozzle 850, but the upper member 110 and the second member 130. It is arranged between the ends of the fuel rod 801.

  Further, even if the cask 900 that stores the fuel rod assembly 800 is dropped, the second-direction buffering member 210 causes the fuel rod 801 to move to the first position due to an impact when the end of the fuel rod 801 collides. Rigidity that does not break through the two-way buffer member 210 in the axial direction is required.

  In this case, when the fuel rod 801 whose end is opposed to the second direction buffer member 210 in the axial direction moves in the axial direction and contacts the second direction buffer member 210, the second direction buffer member 210 and the nozzle The upper member 110 and the second member 130 interposed between the two members 850 absorb the impact transmitted to the fuel rod 801.

  As described above, the second direction buffer member 210 having the same thickness as the upper member 110 and the second member 130 cannot be inserted into the axial gap AS of the fuel rod assembly 800 together with the first member 110 and the second member 130. In addition, the second-direction buffer member 210 is formed of a thin metal plate having a thickness smaller than that of the upper member 110 and the second member 130 and is inserted into the axial gap AS, whereby the fuel rod assembly buffer member 200 is The shock transmitted to the fuel rod 801 is absorbed.

  In addition, when the second direction buffer member 210 is a thin plate, the second direction buffer member 210 may not look like a rod but may look like a plate depending on the ratio of the dimension in the axial direction to the dimension in the first direction. . As in this case, a configuration in which the dimension in the first direction is relatively larger than the dimension in the axial direction is also included in the rod-shaped buffer portion 211.

  When the second-direction buffer member 210 having the above-described configuration is inserted in the radial gap RS in the second direction, the area of the surface perpendicular to the central axis of the guide tube 803 in the entire fuel rod assembly buffer member 200 However, it increases more than the case where only the former member 110 and the second member 130 are attached to the axial gap AS. Therefore, the fuel rod assembly buffer member 200 can reduce the impact received by the fuel rods 801 with more fuel rods 801.

  Specifically, when the fuel rod assembly buffer member 200 is attached to the axial gap AS, the end portion is not the axially opposed fuel rod 801 that does not face the upper member 110 and the end member 130 in the axial direction. There is a case where the second direction buffer member 210 is opposed in the axial direction. As a result, the fuel rod assembly buffer member 200 can reduce the amount of movement in the axial direction with more fuel rods 801 and reduce the impact received by the fuel rods 801 with more fuel rods 801.

  Here, an example of a specific arrangement of the rod-shaped buffer portion 211 will be described below. In the fuel rod assembly buffer member 200, one base side end portion 212 of the plurality of rod-shaped buffer portions 211 is arranged at the coordinates (5, 3), and the tip end portion 213 is arranged at the coordinates (5, 14). Is done. Further, in the fuel rod assembly buffer member 200, the base side end portion 212 of another rod-shaped buffer portion 211 is arranged at coordinates (7, 3) and coordinates (8, 3), and the tip end portion 213 is coordinate (7, 15) and coordinates (8, 15).

  Further, in the fuel rod assembly buffer member 200, the base side end portion 212 of another rod-shaped buffer portion 211 is arranged at coordinates (10, 3) and coordinates (11, 3), and the tip end portion 213 is coordinate (10, 15) and coordinates (11, 15). Further, in the buffer member 200 for the fuel rod assembly, the base side end portion 212 of another rod-shaped buffer portion 211 is arranged at the coordinates (13, 3), and the tip end portion 213 is arranged at the coordinates (13, 14).

  As described above, when the second-direction buffer member 210 is disposed on the fuel rod assembly 800, the fuel rod assembly buffer member 200 includes 252 of the 264 fuel rods 801, each having an end portion. The fuel rod assembly cushioning member 200 is arranged at the opposing position.

  That is, when attached to the fuel rod assembly 800 configured as described above, the fuel rod assembly cushioning member 200 can reduce the amount of movement of the fuel rods 801 in the axial direction by 95% at the maximum and 95% of the total. % Of the fuel rods 801 can reduce the impact received by the fuel rods 801.

  Here, in the present embodiment, the upper member 110 and the second member 130 and the second direction buffer member 210 are described as being attached to the axial gap AS one by one. A plurality of the 130 and second direction buffer members 210 may be attached to the axial gap AS in the axial direction.

  For example, when the total thickness in the axial direction of the upper member 110 and the second member 130 and the second direction buffer member 210 is less than the size of the axial clearance AS, the upper member 110 and the second member 130, At least one of the two-direction buffer members 210 is attached to the axial gap AS.

  Thus, the fuel rod assembly buffer member 100 can fill the gap between the end of the fuel rod 801 and the nozzle 850 with the upper member 110 and the second member 130 and the second direction buffer member 210. . As a result, the fuel rod assembly buffer member 100 can reduce the axial movement distance of the fuel rod 801.

  Here, when the plurality of upper members 110 and the end members 130 and the plurality of second direction buffer members 210 are arranged in the axial gap AS, the arrangement includes, for example, the upper member 110 in the axial direction of the fuel rod. And the order of the member 130, the upper member 110 and the member 130, the second direction buffer member 210, and the second direction buffer member 210 is conceivable.

  However, in the buffer member 100 for the fuel rod assembly, the upper member 110 and the end member 130 and the second direction buffer member 210 are alternately arranged in the axial gap AS, rather than such an arrangement. Is preferred. The reason will be described below.

  For example, when the second direction buffer member 210 is disposed closer to the fuel rod 801 than the upper member 110 and the end member 130 in the axial direction of the fuel rod, the end portion is only on the upper member 110 and the end member 130. The fuel rods 801 opposed in the axial direction move in the axial direction until the end portions thereof contact the upper member 110 and the second member 130.

  Here, if the upper member 110 and the second member 130 and the second direction buffer member 210 are alternately disposed in the axial gap AS, the second direction buffer member 210 is not disposed to overlap in the axial direction. Therefore, the distance between the end of the fuel rod and the upper member 110 and the second member 130 is reduced. Thereby, the buffer member 100 for fuel rod assemblies according to the present invention can reduce the movement distance of the fuel rod in the axial direction.

(Embodiment 3)
FIG. 9 is a projection view in the axial direction of the fuel rod assembly cushioning member of Embodiment 3 attached to the fuel rod assembly. The fuel rod assembly buffer member 300 of the third embodiment is different from the fuel rod assembly buffer member 100 shown in FIG. 7 in the insertion direction of the rod-shaped buffer portion 111 into the axial gap AS.

  Here, in the fuel rod assembly 800 shown in FIG. 7 and FIG. 9, the fuel rods 801 are bundled by the grid 810 shown in FIG. Here, when the rectangular column is cut along a virtual plane VF01 orthogonal to the central axis of the control rod guide tube 803a, one side 802a of the cross section of the rectangular column shown in FIG. 7 is along the first direction. Further, the side 802b adjacent to the one side 802a is along the second direction. That is, in the fuel rod assembly cushioning member 100 shown in FIG. 7, the rod-shaped cushioning portion 111 is inserted into the radial gap RS in parallel with the one side 802a.

  On the other hand, the first direction shown in FIG. 9 is a direction inclined to one side 802a of the cross section of the quadrangular prism on a virtual plane VF01 orthogonal to the central axis of the control rod guide tube 803a. Specifically, the first direction is a direction inclined by, for example, 45 degrees with respect to the side 802a on the virtual plane VF01.

  Further, the second direction is a direction inclined to the side 802b adjacent to the one side 802a. Specifically, the second direction is a direction inclined by, for example, 45 degrees with respect to the side 802b on the virtual plane VF01. In the present embodiment, the first direction and the second direction are orthogonal to each other. The first direction and the second direction may be directions that intersect with each other, even if they are not orthogonal to each other.

  In this way, the fuel rod assembly buffer member 300 shown in FIG. 9 is inserted into the radial gap RS in the direction in which the rod-shaped buffer portion 311 as the first-direction rod-shaped buffer portion is inclined with respect to the one side 802a. Is done.

  The fuel rod assembly cushioning member 300 is configured by being divided into an upper member 310 and a second member 330. The fuel rod assembly buffer member 300 is configured by being divided into an upper member 310 and a second member 330, for example, on a virtual plane VF03 including the central axis of the control rod guide tube 803a. The virtual plane VF03 is, for example, a plane that is orthogonal to a virtual straight line along the first direction and is a plane that is inclined with respect to the one side 802a.

  The upper member 310 is inserted into the radial clearance RS in the direction in which the rod-shaped buffer portion 311 faces the virtual plane VF03. Further, the end member 330 is inserted into the radial gap RS in the direction in which the rod-shaped buffer portion 331 is directed toward the virtual plane VF03.

  When the rod-shaped buffer portion 311 having the above-described configuration is inserted into the radial clearance RS, the central axis of the guide tube 803 in the entire fuel rod assembly buffer member 300 is larger than when the first direction is parallel to the one side 802a. The area of the surface orthogonal to Therefore, the fuel rod assembly buffer member 300 can reduce the impact received by the fuel rods 801 with more fuel rods 801.

  Here, as an example of a configuration for attaching the fuel rod assembly buffer member 300 to the fuel rod assembly 800, coordinates where the rod-shaped buffer portion 311 of the upper member 310 is disposed will be described.

  In the fuel rod assembly buffer member 300, one base side end 312 of the plurality of rod-shaped buffer portions 311 is arranged at coordinates (15, 7) and coordinates (15, 8), and a tip portion 313 is coordinated. (13, 5) and coordinates (13, 6). Further, the fuel rod assembly buffer member 300 has a base side end 312 of another rod-shaped buffer 311 arranged at coordinates (15, 10) and coordinates (15, 11), and a tip 313 at coordinates (12, 7) and coordinates (11, 7).

  The fuel rod assembly buffer member 300 has a base side end 312 of another rod-shaped buffer 311 arranged at coordinates (15, 13) and coordinates (15, 14), and a tip 313 at coordinates (10, 8) and coordinates (10, 9). The fuel rod assembly buffer member 300 has a base side end 312 of another rod-shaped buffer 311 arranged at coordinates (14, 15) and coordinates (13, 15), and a tip 313 at coordinates (9, 10) and coordinates (8, 10).

  Further, the fuel rod assembly buffer member 300 has the base side end portion 312 of another rod-shaped buffer portion 311 arranged at the coordinates (15, 11) and the coordinates (15, 10), and the tip end portion 313 at the coordinates (7, 11) and coordinates (7, 12). The fuel rod assembly cushioning member 300 has a base side end 312 of another rod-shaped buffer 311 arranged at coordinates (8, 15) and coordinates (7, 15), and a tip 313 at coordinates (6, 13). The bar-shaped buffer portion 331 of the second member 330 is arranged in plane symmetry with the bar-shaped buffer portion 311 with respect to the virtual plane VF03.

  With the above configuration, when the fuel rod assembly buffer member 300 is attached to the fuel rod assembly 800, 234 of the 264 fuel rods 801 are positioned at positions facing the respective end portions. The member 300 is arranged.

  In other words, the fuel rod assembly cushioning member 300 can reduce the amount of movement of the fuel rods 801 in the axial direction by 89% at the maximum and only 89% of the fuel by using only the upper member 310 and the second member 330. The impact received by the fuel rod 801 by the rod 801 can be reduced.

(Embodiment 4)
FIG. 10 is a projected view of the fuel rod assembly cushioning member of the fourth embodiment attached to the fuel rod assembly in the axial direction. The fuel rod assembly buffer member 400 of the fourth embodiment includes a second direction buffer member 410 configured in the same manner as the second direction buffer member 210 shown in FIG. 8.

  However, the second-direction buffer member 210 shown in FIG. 8 is inserted into the radial gap RS in parallel with the side 802b on the virtual plane VF01 orthogonal to the central axis of the control rod guide tube 803a. The second-direction buffer member 410 shown is inserted into the radial gap RS in the direction in which the rod-shaped buffer portion 411 serving as the second-direction rod-shaped buffer portion is inclined with respect to the side 802b.

  When the rod-shaped buffer portion 411 having the above-described configuration is inserted in the radial gap RS in the second direction, the area of the surface perpendicular to the central axis of the guide tube 803 in the entire fuel rod assembly buffer member 400 is It increases more than the case where only the member 310 and the second member 330 are attached to the axial gap AS. Therefore, the fuel rod assembly buffer member 400 can reduce the impact received by the fuel rods 801 with more fuel rods 801.

  Here, as an example of a configuration for attaching the fuel rod assembly buffer member 400 to the fuel rod assembly 800, coordinates where the rod-shaped buffer portion 411 of the second direction buffer member 410 is disposed will be described.

  The fuel rod assembly buffer member 400 has one base side end portion 412 of the plurality of rod-shaped buffer portions 411 arranged at the coordinates (3, 8) and coordinates (3, 9), and the tip end portion 413 is coordinated. (7, 4). The fuel rod assembly cushioning member 400 has a base side end 412 of another rod-shaped cushioning portion 411 arranged at coordinates (3, 10) and coordinates (3, 11), and a tip portion 413 at coordinates (10, 4).

  Further, in the buffer member 400 for the fuel rod assembly, the base side end portion 412 of another rod-shaped buffer portion 411 is arranged at the coordinates (4, 13), and the tip end portion 413 is arranged at the coordinates (13, 4). Further, in the buffer member 400 for the fuel rod assembly, the base side end portion 412 of another rod-shaped buffer portion 411 is arranged at the coordinates (5, 14), and the tip end portion 413 is arranged at the coordinates (14, 5).

  The fuel rod assembly cushioning member 400 has a base side end portion 412 of another rod-shaped buffer portion 411 arranged at coordinates (7, 15) and coordinates (8, 15), and a tip portion 413 at coordinates (14, 8). Further, the fuel rod assembly buffer member 400 has a base side end portion 412 of another rod-shaped buffer portion 411 arranged at coordinates (10, 15) and coordinates (11, 15), and a tip end portion 413 at coordinates (14, 11).

  With the above configuration, when the fuel rod assembly buffer member 400 is attached to the fuel rod assembly 800, 264 of the 264 fuel rods 801 are positioned at positions facing the respective end portions. The member 400 is disposed.

  That is, the shock absorber member 400 for the fuel rod assembly has a maximum axial direction of all the fuel rods 801 by arranging the upper member 310 and the end member 330 and the second direction shock absorber member 410 in the axial clearance AS. The amount of movement of the fuel rods 801 can be reduced, and the impact of the fuel rods 801 on all the fuel rods 801 can be reduced.

(Embodiment 5)
FIG. 11 is a projection view in the axial direction of the fuel rod assembly cushioning member of Embodiment 5 attached to the fuel rod assembly. The fuel rod assembly cushioning member 500 of the fifth embodiment shown in FIG. 11 is characterized in that a projecting cushioning member 530 is provided on the rod-shaped cushioning portion 511 along the first direction so as to be movable in the second direction.

  The fuel rod assembly buffer member 500 includes a storage space 513 and a protruding buffer member 530. The storage space 513 is a hole that opens in the side wall surface 512 of the rod-shaped buffer portion 511. The protruding buffer member 530 is formed smaller than the storage space 513. Thereby, the protruding buffer member 530 is stored in the storage space 513 without protruding from the storage space 513.

  The protruding buffer member 530 is stored in the storage space 513 so that it can move in the second direction with respect to the rod-shaped buffer portion 511. Specifically, the projecting cushioning member 530 includes a wall surface along the virtual plane VF01 orthogonal to the central axis of the control rod guide tube 803a among the wall surfaces of the storage space 513, and a wall surface along the virtual plane VF01 among its own wall surfaces. Are moved in the second direction with respect to the rod-shaped buffer 511 by sliding on each other.

  FIG. 12 is a cross-sectional view showing the cam mechanism cut along a virtual plane orthogonal to the central axis of the control rod guide tube. Next, pressing force application means for moving the protruding buffer member 530 in the second direction will be described. The fuel rod assembly buffer member 500 includes, for example, a cam mechanism 540 as a pressing force application unit. The cam mechanism 540 includes a shaft 541, a cam 542, an engagement portion 543, and a tension spring 544.

  The shaft 541 is provided along the first direction. Specifically, the shaft 541 is provided inside a hole formed in the rod-shaped buffer portion 511 along the first direction. The shaft 541 is supported so as to be rotatable inside the hole.

  FIG. 13 is a cross-sectional view of the imaginary plane parallel to the central axis of the control rod guide tube, with the cam mechanism cut. FIG. 14 is a cross-sectional view showing the cam mechanism in a state in which the protruding buffer member protrudes from the storage space, cut along an imaginary plane parallel to the central axis of the control rod guide tube.

  As shown in FIG. 13, the cam 542 is attached to the shaft 541 and rotates around the central axis of the shaft 541 together with the shaft 541. The distance from the side periphery of the cam 542 to the shaft 541 is formed unevenly. The engaging portion 543 is a portion with which the side peripheral portion of the cam 542 is in contact with the protruding buffer member 530. The tension spring 544 attracts the protruding buffer member 530 in the direction in which the protruding buffer member 530 is stored in the storage space 513.

  As described above, in the cam mechanism 540, as shown in FIG. 14, the force by which the shaft 541 rotates and the side peripheral portion of the cam 542 pushes the engaging portion 543 in the second direction is larger than the spring force of the tension spring 544. Then, the projecting buffer member 530 moves in the second direction. As a result, in the fuel rod assembly buffer member 500, the projecting buffer member 530 projects from the storage space 513 in the second direction.

  Further, when the shaft 541 rotates and the force by which the side peripheral portion of the cam 542 pushes the engaging portion 543 in the second direction becomes smaller than the spring force of the tension spring 544, the protruding buffer member 530 is stored in the storage space 513. The projecting cushioning member 530 moves in the second direction in the first direction. As a result, in the fuel rod assembly buffer member 500, the protruding buffer member 530 is stored in the storage space 513.

  Here, although there are two directions in the second direction, as shown in FIG. 11, the buffer member 500 for the fuel rod assembly protrudes in one direction out of the second direction, and protrudes in the other direction. Projecting cushioning member 530 is formed. That is, the plurality of bar-shaped buffer portions 511 include those in which the storage space 513 is opened on both side wall surfaces 512.

  Here, the protruding buffer member 530 has a length in the first direction that is the size of the radial gap RS formed between the side peripheral portions of the plurality of guide tubes 803 arranged in the first direction. It is formed below. Thereby, when the protruding buffer member 530 protrudes from the storage space 513 in the second direction, the radial gap formed between the side peripheral portions of the guide tubes 803 arranged in the first direction. It can be placed in the RS.

  Next, a procedure for attaching the fuel rod assembly cushioning member 500 to the fuel rod assembly 800 will be described. First, in a state where the protruding buffer member 530 shown in FIG. 11 is stored in the storage space 513, the rod-shaped buffer portion 511 is inserted into the radial gap RS along the first direction. Next, the shaft 541 shown in FIG. 12 is rotated so that the protruding buffer member 530 protrudes from the storage space 513 in the second direction.

  Next, a procedure for removing the fuel rod assembly buffer member 500 from the fuel rod assembly 800 will be described. First, the shaft 541 shown in FIG. 12 is rotated to store the protruding buffer member 530 in the storage space 513. Next, in a state where the protruding buffer member 530 shown in FIG. 11 is stored in the storage space 513, the rod-shaped buffer portion 511 is pulled out from the radial gap RS along the first direction.

  With the above configuration, when the fuel rod assembly buffer member 500 is attached to the fuel rod assembly 800, the 264 of the 264 fuel rods 801 are disposed at positions facing the respective end portions. The member 500 is disposed. That is, the fuel rod assembly buffer member 500 can reduce the amount of movement of all the fuel rods 801 in the axial direction at the maximum, and can reduce the impact received by the fuel rods 801 on all the fuel rods 801.

  Here, the pressing force applying means is not limited to the cam mechanism 540. The pressing force applying means is, for example, a hole formed in the rod-shaped buffer portion 511, and one end portion opens to the storage space 513 and the other end portion opens to the outside of the rod-shaped buffer portion 511. The structure may be such that air is supplied to the storage space 513 through the hole.

  In this case, the air supplied to the storage space 513 moves the protruding cushioning member 530 in the second direction. Even in this configuration, the pressing force applying means can cause the protruding buffer member 530 to protrude from the storage space 513 in the second direction.

  FIG. 15 is a cross-sectional view showing the spring push-out mechanism cut along a virtual plane orthogonal to the central axis of the control rod guide tube. The pressing force applying means may be, for example, a spring pushing mechanism 640 shown in FIG. The spring pushing mechanism 640 includes a pushing spring 641 and a taper 642.

  The push spring 641 pushes the protruding buffer member 530 in a direction in which the protruding buffer member 530 protrudes from the storage space 513 in the second direction. Thereby, the protrusion buffering member 530 protrudes from the storage space 513 when the external force is removed.

  The cam 542 is formed in a portion of the protruding buffer member 530 that interferes with the guide tube 803 when the rod-shaped buffer portion 511 is inserted into the radial gap RS and pulled out from the radial gap RS. . That is, the taper 642 is formed on two wall surfaces facing the side peripheral portion of the guide tube 803 among the wall surfaces of the protruding buffer member 530. The taper 642 is a slope whose distance to the side peripheral portion of the guide tube 803 increases as the distance from the storage space 513 increases.

  With the above configuration, when the rod-shaped buffer portion 511 is inserted into the radial clearance RS with the protruding buffer member 530 protruding from the storage space 513, the taper 642 contacts the side peripheral portion of the guide tube 803. Then, the protruding buffer member 530 receives a force in the direction stored in the storage space 513 from the guide tube 803. As a result, the protruding buffer member 530 is stored in the storage space 513.

  When the rod-like buffering portion 511 is further inserted into the radial gap RS in the first direction and the protruding buffer member 530 passes through the guide tube 803, the protruding buffer member 530 is stored in the storage space by the spring force of the push spring 641. Project from 513. Thus, the fuel rod assembly buffer member 500 is disposed in the radial clearance RS of the guide tube 803 in which the protruding buffer members 530 are arranged in the first direction.

  Further, when the rod-shaped buffer portion 511 is moved so as to be pulled out from the radial clearance RS with the protruding buffer member 530 protruding from the storage space 513, the taper 642 comes into contact with the side peripheral portion of the guide tube 803 and protrudes. The buffer member 530 receives a force in the direction stored in the storage space 513 from the guide tube 803. Then, the protruding buffer member 530 is stored in the storage space 513. Thereby, the rod-shaped buffer part 511 can be extracted from the radial clearance RS.

  With the above configuration, the spring push-out mechanism 640 can apply a force acting in the second direction to the protruding buffer member 530 while suppressing an increase in the number of parts.

  As described above, the fuel rod assembly buffer member is useful when the fuel rod assembly is stored in a cask and transported, and is suitable for reducing the impact received by the fuel rod.

DESCRIPTION OF SYMBOLS 100 Buffer member for fuel rod assembly 110 Upper member 111 Rod-shaped buffer portion 112 Side wall surface 113 Root side end portion 114 Tip portion 115 Connection buffer portion 116 Base portion 117 Side portion 118 Tip portion 130 End member 131 Rod-shaped buffer portion 134 Tip portion 137 side Part 138 Tip part 200 Fuel rod assembly buffer member 210 Second direction buffer member 211 Rod-like buffer part 212 Root side end part 213 Tip part 215 Connection buffer part 300 Fuel rod assembly buffer member 310 Upper member 311 Rod-like buffer part 312 Root side end 313 Tip portion 330 End member 331 Rod-shaped buffer portion 400 Fuel rod assembly buffer member 410 Second direction buffer member 411 Rod-shaped buffer portion 412 Root side end portion 413 Tip portion 500 Fuel rod assembly buffer member 511 Bar-shaped buffer part 512 Side wall surface 513 Storage space 530 Projection buffer part 540 Cam mechanism 541 Shaft 542 Cam 543 Engagement part 544 Tensile spring 640 Spring pushing mechanism 641 Pushing spring 642 Taper 800 Fuel rod assembly 801 Fuel rod 802 Fuel rod group 802a One side 802b Side 803 Guide tube 803b Control rod guide tube 803b Guide tube 810 Grid 850 Nozzle 851 First nozzle 852 Second nozzle 900 Cask 910 Body main body 920 Bottom 930 Lid 940 Basket 941 Cell AS Axial gap RS Radial gap

Claims (9)

A nozzle disposed between the end of the fuel rod and the end of the fuel rod opposite to the end of the fuel rod with an axial gap between the end of the fuel rod;
A plurality of guide tubes connected to the nozzle and having radial gaps between the respective side peripheral portions, each center axis being provided along the axial direction;
A fuel rod assembly buffer member attached to a fuel rod assembly comprising:
A buffer member for a fuel rod assembly, wherein at least a part of the radial gap is inserted in a direction perpendicular to the central axis and disposed in the axial gap. A plurality of first-direction bar-shaped buffer portions formed in a first direction perpendicular to the central axis and inserted into the radial gap;
A plurality of first-direction bar-shaped buffering portions are connected to the guide tube-side portion at intervals equal to or greater than the diameter of the guide tube in a second direction orthogonal to the central axis and the first direction. Directional coupling buffer,
The buffer member for a fuel rod assembly according to claim 1, comprising:   The fuel rod assembly cushioning member according to claim 2, wherein a plurality of the first direction rod-shaped cushioning portions are arranged in the axial gap. A plurality of second-direction bar-shaped buffer portions formed in the second direction and inserted into the radial gap;
A plurality of second-direction bar-shaped buffering portions connected to the guide-tube-side portion with a gap equal to or larger than the diameter of the guide tube in the first direction;
The buffer member for a fuel rod assembly according to claim 2 or 3, wherein   5. The fuel rod assembly buffer member according to claim 4, wherein a plurality of the second direction rod-shaped buffer portions are arranged in the axial gap.   6. The fuel rod assembly according to claim 3, wherein the first-direction rod-shaped buffer portions and the second-direction rod-shaped buffer portions are alternately arranged in the axial gap. Body cushioning member. The first direction is
2. A direction inclined on the virtual plane with respect to one side of a cross section obtained by cutting a quadrangular prism formed by bundling a plurality of the fuel rods along a virtual plane orthogonal to the central axis. The buffer member for a fuel rod assembly according to any one of claims 2 to 6. Each side of the plurality of guide tubes stored in the storage space formed in the first-direction bar-shaped buffer portion so as to be movable in the second direction and arranged in the first direction. A protruding cushioning member in which the dimension in the first direction is formed below the size of the radial gap formed between the circumferential part and
A pressing force applying means for applying a force toward the protruding buffer member in the second direction;
The buffer member for a fuel rod assembly according to claim 2, comprising: A storage portion for storing a fuel rod assembly to which a buffer member for a fuel rod assembly is attached;
A main body portion for storing the storage portion;
A transport container comprising:
The fuel rod assembly is
A nozzle disposed between the end of the fuel rod and the end of the fuel rod opposite to the end of the fuel rod with an axial gap between the end of the fuel rod;
A plurality of guide tubes connected to the nozzle and having radial gaps between the respective side peripheral portions, each center axis being provided along the axial direction;
Comprising
The buffer member for the fuel rod assembly is
The transport container, wherein at least a part of the radial gap is inserted in a direction orthogonal to the central axis and is disposed in the axial gap.

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