JP2013088303A - Fuel holder, method for using fuel holder, and method for transporting fuel assembly - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel holder capable of preventing a fuel rod from being damaged by sufficiently bringing out buffer performance of a handle in a fuel assembly when the fuel assembly housed in the fuel holder receives a load from a top cover of the fuel holder due to a fall of the fuel holder, or the like.SOLUTION: In the fuel holder, one end opening part of a housing shell which can house a fuel assembly is closed by a top cover, the fuel assembly having a grid holding a tip of the fuel rod, a pair of legs provided on a surface opposite from a surface holding the fuel rod of the grid and erected on a diagonal line of an almost square plate-shaped grid, and an almost U-shaped handle having a tip for connecting the pair of legs. In the fuel holder, an inner surface has a contact part with which the tip is brought into contact and a slide prevention part for preventing the handle from sliding on the inner surface so as to keep the position of the tip brought into contact with the inner surface, when the handle receives load from the inner surface of the top cover. A method for using the fuel holder and a method for transporting the fuel assembly are provided.

Description

  The present invention relates to a fuel holder, a method for using the fuel holder, and a method for transporting the fuel assembly. More specifically, the fuel holder can prevent the fuel rod from being damaged even in an unexpected situation such as the fuel holder dropping. , Method of using fuel holder, and method of transporting fuel assembly, in particular, fuel holder capable of accommodating fuel assembly used in boiling water reactor, method of using fuel holder, and method of transporting fuel assembly About.

  A fuel assembly used in a light water reactor such as a boiling water reactor and a pressurized water reactor is accommodated in a fuel holder, and this fuel holder is further loaded in a transport container and transported to a demand place. In the fuel assembly, a large number of fuel rods are bundled at both ends by an upper tie plate and a lower tie plate, and a support grid is provided between the upper tie plate and the lower tie plate to keep the spacing between the fuel rods. Has been made. The fuel holder includes a housing shell having a long inner space, an upper lid and a lower lid for closing the opening portions at both ends of the housing shell, and a fuel assembly is housed in the inside.

  The fuel assembly and the fuel holder that accommodates the fuel assembly include a buffer function having a role of suppressing vibration transmitted from the trailer or the like to the fuel assembly when the fuel assembly is transported to a demand place by the trailer or the like, and a trailer A buffering function or the like is usually provided to prevent the fuel rod from being damaged under special conditions such as the transport container dropping from the top.

  As a buffering function, for example, in Patent Document 1, “・ ・ A gap is provided between the top of the fuel body and the top of the fuel protection container or the top cover of the fuel protection container, and the size of the gap is 50 mm or less. A fuel protection container for mixed oxide fuel bodies for boiling water reactors. ”(Refer to claim 1)“ In the gap portion, a resin material, a rubber material or a honeycomb having a thickness equal to or less than the size of the gap. A fuel protective container for a mixed oxide fuel body for a boiling water reactor according to claim 1, characterized in that a soft material such as a material is installed ”(refer to claim 2).

  According to the invention according to Patent Document 1, “With regard to the transportation of the MOX fuel body with heat generation, even if a large longitudinal acceleration of about 1.0 G occurs during transportation, it can be protected without impairing the soundness of the fuel body. “The tightening force of the fuel body loaded at room temperature is maintained even at high temperatures, and the tightening force management becomes extremely easy” (see paragraph 0061).

  Patent Document 2 states that “a rectangular cylinder-shaped fuel protective container that can be transported by being accommodated in a basket hole of a fuel transport container is provided, and the fuel protective container has a side lid that covers the side of the container body, and an upper tie plate. The upper side lid corresponding to the position, the middle side lid, and the lower side lid corresponding to the lower tie plate position are configured in at least a three-part structure, and the tightening force of each divided side lid is individually adjusted to protect the fuel A fuel protection device for a nuclear reactor fuel, characterized in that the tightening force of the fuel body accommodated in the vessel can be adjusted according to the vibration characteristics of the fuel body. "(See claim 9 of Patent Document 2). ), “A rectangular tube-shaped fuel protection container that is accommodated in the basket hole of the fuel transportation container and can be transported is provided, and the fuel protection container corresponds to the upper tie plate and the lower tie plate of the fuel body housed therein. Tie plate tightening mechanism in position Reactor fuel fuel protection device, wherein each of the tie plate tightening mechanisms is provided with a fastener that can be moved back and forth toward the accommodated fuel body. ”(Claim 10 of Patent Document 2) Reference.).

Patent Document 3, by "the tightening mechanism, characterized in that it comprises a step of at least lashing the upper tie plate section and the fuel assembly by tightening the two or more positions of the lower tie plate portion and the inner container or the like according to The method for transporting the boiling water reactor fuel body according to Item 1 ”(see claim 3 of Patent Document 3) is described.

  For example, the fuel holder has a situation in which the fuel holder falls when the fuel holder is loaded into a transportation container that accommodates the fuel holder, and a situation in which the transportation container falls from a trailer or the like when the transportation container is transported to a demand place. Should it occur, it must be configured to protect the fuel assembly. Under special conditions such as the fuel holder or the transport container falling, the fuel assembly may receive a large load from the upper lid and the lower lid due to an impact at the time of dropping. The upper tie plate and the lower tie plate provided in the fuel assembly not only have a function of bundling a plurality of fuel rods while maintaining a distance, but also protect the fuel rods under special conditions such that the fuel holder falls. It also has a buffer function. The upper tie plate and the lower tie plate are energy that acts on the fuel rods by plastic deformation of the upper and lower tie plates when the fuel assembly receives a certain load from the upper and lower lids. And is configured to protect the fuel rods.

  The upper tie plate has a U-shaped handle having a pair of legs and a tip. This handle is not only configured to lift and move the fuel assembly when the fuel assembly is housed in the fuel holder, but also when the transport container falls with the upper tie plate down The handle is configured so that the tip of the handle receives a load from the upper lid of the fuel holder and the pair of legs of the handle is plastically deformed to reduce energy acting on the fuel rod and protect the fuel rod. Yes.

Japanese Patent No. 3080897 Japanese Patent No. 3080895 Japanese Patent No. 3142493

  By the way, when the fuel holder is dropped from several meters above the ground and an evaluation test of the cushioning performance of the handle is performed, the leg portion of the handle may be plastically deformed with a load smaller than the assumed load. . If the leg portion of the handle is plastically deformed with a load smaller than the assumed load, the energy absorbed by the plastic deformation is reduced, so that the buffer performance is deteriorated. When the cushioning performance of the handle is lowered, a larger energy than expected is applied to the fuel rod, and the fuel rod may be damaged.

  An object of the present invention is to provide a fuel rod that exhibits a buffering performance of a handle in a fuel assembly when the fuel assembly accommodated in the fuel holder is subjected to a load from an upper lid of the fuel holder due to a drop of the fuel holder or the like. It is providing the fuel holder which can prevent that is damaged.

Means for solving the problems are as follows:
(1) A grid that holds the tip of the fuel rods and a surface of the grid opposite to the surface on which the fuel rods are held are provided, and stand on diagonal lines of the substantially square disk-shaped grid. A fuel holder for closing one end opening of a containing shell capable of containing a fuel assembly having a pair of legs and a substantially U-shaped handle having a tip connecting the pair of legs with an upper lid. There,
When the handle receives a load from the inner surface of the upper lid, the inner surface is in contact with the tip and the handle is on the inner surface so that the position of the tip is in contact with the inner surface. It is a fuel holder characterized by having a sliding prevention part which prevents sliding.

As a preferred embodiment of the above (1),
(2) The fuel holder according to (1), wherein a concave portion is formed by the contact portion and the anti-slip portion.
(3) The said recessed part is provided so that the projection image obtained by projecting the said front-end | tip part on the said inner surface from the axial direction of the said fuel assembly may be provided. A fuel holder,
(4) The fuel holder according to (3), wherein the recess extends in a longitudinal direction of the projected image.
(5) The fuel holder according to (1), wherein the anti-skid part is a convex part,
(6) The convex portion extends in a longitudinal direction of a projected image obtained by projecting the tip portion onto the inner surface from an axial direction of the fuel assembly. A fuel holder,
(7) The anti-sliding portion is a guide plate that rises from the inner surface in the axial direction, and a gap is provided between the tip portion and the inner surface, and the axial length of the guide plate is the axial direction of the gap. It is a fuel holder as described in said (1) characterized by being larger than length,
(8) The fuel holder according to any one of (1) to (6), wherein when the fuel assembly is accommodated, the tip end portion contacts the inner surface.

Means for solving the other problems are as follows:
(9) A method of using a fuel holder, wherein the fuel assembly is accommodated in the fuel holder according to any one of (1) to (8).

Means for solving the still another problem is as follows.
(10) A method of transporting a fuel assembly, wherein the fuel assembly is accommodated in the fuel holder according to any one of (1) to (8) and transported.

  According to the fuel holder of the present invention, when the fuel assembly accommodated in the fuel holder is subjected to a load from the upper lid of the fuel holder due to the dropping of the fuel holder or the like, the position of the tip of the handle that contacts the inner surface of the upper lid is determined. The inner surface of the upper lid has a contact portion with which the tip contacts and a slip prevention portion that prevents the handle from sliding on the inner surface, so that the buffer performance of the handle in the fuel assembly is exhibited. Thus, the fuel rod can be prevented from being damaged.

  According to the method of using the fuel holder according to the present invention, even if an unexpected situation occurs such as when the fuel holder falls when the fuel holder is loaded into a transport container that houses the fuel holder, the fuel holder is used. Therefore, the fuel rod can be prevented from being damaged by sufficiently exhibiting the buffer performance of the handle in the fuel assembly.

  The method for transporting a fuel assembly according to the present invention provides an unforeseen situation in which the fuel holder falls when the fuel holder is loaded into a transport container that accommodates the fuel holder, and the transport container in which the fuel holder is accommodated. Even if an unforeseen situation such as a transport container falling from a trailer or the like occurs when transporting to the fuel assembly, the fuel assembly is transported using the fuel holder, so that the handle cushioning performance in the fuel assembly is fully exhibited. This can prevent the fuel rod from being damaged.

FIG. 1 is a partial cross-sectional schematic view of a fuel holder and a fuel assembly, showing one embodiment of a fuel holder according to the present invention. FIG. 2 is a schematic cross-sectional view of the fuel holder and the fuel assembly obtained by cutting the fuel holder and the fuel assembly shown in FIG. 1 at a cut surface passing through the line segment AA ′. FIG. 3 is a schematic cross-sectional view of the main part of the fuel holder and the fuel assembly when the tip of the handle slips on the inner surface of the upper lid when the fuel holder is dropped. FIG. 3A is a cross-sectional explanatory view of main parts of the fuel holder and the fuel assembly when the fuel assembly collides with the fuel holder in the fuel holder and the fuel assembly shown in FIG. FIG. 3B is a schematic cross-sectional view of the main part of the fuel holder and the fuel assembly obtained by cutting the fuel holder and the fuel assembly shown in FIG. 3A along a section passing through the line BB ′. FIG. 4 is a schematic cross-sectional view of the main part of the fuel holder and the fuel assembly when the tip of the handle is held at a specific position on the inner surface of the upper lid when the fuel holder is dropped. FIG. 4A is a cross-sectional explanatory view of main parts of the fuel holder and the fuel assembly shown in FIG. 1 when the fuel assembly collides with the fuel holder. FIG. 4B is a schematic cross-sectional view of the main part of the fuel holder and the fuel assembly obtained by cutting the fuel holder and the fuel assembly shown in FIG. 4A along a section passing through the line segment CC ′. FIG. 5 is a model diagram illustrating the relationship between the compressive displacement of the handle and the load when the tip of the handle slips on the inner surface of the upper lid when the fuel holder is dropped. FIG. 6 is a model diagram showing the relationship between the compressive displacement of the handle and the load when the tip of the handle is held at a specific position on the inner surface of the upper lid when the fuel holder is dropped. FIG. 7 is a schematic cross-sectional view of a main part of the fuel holder and the fuel assembly, showing an example of an upper lid in the fuel holder of the present invention. FIG. 8 is a schematic view of the inner surface of the upper lid shown in FIG. 7 as viewed from the axial direction of the fuel holder. FIG. 9A is a schematic cross-sectional view of the main part of the fuel holder and the fuel assembly, showing a state where the handle of the fuel assembly shown in FIG. 7 is deformed. FIG. 9B is a schematic cross-sectional view of a main part of the fuel holder and the fuel assembly obtained by cutting the fuel holder and the fuel assembly shown in FIG. 9A along a section passing through the line EE ′. FIG. 10 is a schematic cross-sectional view of a main part of the fuel holder and the fuel assembly, showing an example of an upper lid in the fuel holder of the present invention. FIG. 11 is a schematic view of the inner surface of the upper lid shown in FIG. 10 as viewed from the axial direction of the fuel holder. FIG. 12A is a schematic cross-sectional view of the main part of the fuel holder and the fuel assembly, showing a state in which the handle of the fuel assembly shown in FIG. 10 is deformed. FIG. 12B is a schematic cross-sectional view of the main part of the fuel holder and the fuel assembly obtained by cutting the fuel holder and the fuel assembly shown in FIG. 12A along a section passing through the line segment FF ′. FIG. 13 is a schematic cross-sectional view of a main part of a fuel holder and a fuel assembly, showing an example of an upper lid in the fuel holder of the present invention. FIG. 14 is a schematic view of the inner surface of the upper lid shown in FIG. 13 as viewed from the axial direction of the fuel holder. FIG. 15A is a schematic cross-sectional view of the main part of the fuel holder and the fuel assembly, showing a state in which the handle of the fuel assembly shown in FIG. 13 is deformed. FIG. 15B is a schematic cross-sectional view of the main part of the fuel holder and the fuel assembly obtained by cutting the fuel holder and the fuel assembly shown in FIG. 15A along a section passing through the line GG ′.

Hereinafter, a fuel holder according to the present invention will be described with reference to the drawings.
FIG. 1 is a partial cross-sectional schematic view of a fuel holder and a fuel assembly, showing one embodiment of a fuel holder according to the present invention. FIG. 2 is a schematic cross-sectional view of the fuel holder and the fuel assembly obtained by cutting the fuel holder and the fuel assembly shown in FIG. 1 at a cut surface passing through the line segment AA ′.

  As shown in FIGS. 1 and 2, the fuel holder 1 includes a housing shell 2, and an upper lid 3 and a lower lid 4 that close both ends of the housing shell 2, and the housing shell 2, the upper lid 3, and the lower lid 4. The fuel assembly 10 can be accommodated in an internal space surrounded by the. The fuel holder 1 includes a fixed plate 5 that supports the fuel assembly 10, a receiving plate 6, an urging means 7, and a pedestal 8. The fuel holder 1 is an embodiment of the fuel holder according to the present invention.

  The fuel assembly 10 accommodated in the fuel holder 1 is configured by a plurality of fuel rods 11 and a water pipe (not shown) being bundled by an upper tie plate 12, a support lattice 13, and a lower tie plate 14.

  The housing shell 2 has a substantially square cylindrical shape, and has a size that allows the fuel assembly 10 to be housed in an internal space surrounded by the upper lid 3 and the lower lid 4 provided at both ends of the housing shell 2. The housing shell 2 is not particularly limited as long as it is a material that satisfies the temperature conditions from when the fuel assembly 10 is accommodated to when the fuel assembly 10 is conveyed, the required mechanical strength, and the like. Steel, boron-containing stainless steel, heat-resistant nickel-base alloy, and the like can be employed.

  Each of the upper lid 3 and the lower lid 4 is preferably fixed to the housing shell 2. In addition, it does not specifically limit as a fixing means, Well-known means, such as adhesion | attachment, welding, engagement, fitting, or screwing, or means easily conceivable by those who have normal knowledge in the technical field of this invention are adopted. can do. The upper lid 3 and the lower lid 4 can be formed of the same material as the housing shell 2.

  In many cases, the housing of the fuel assembly 10 in the housing shell 2 is usually performed with the housing shell 2 and the fuel assembly 10 standing upright. The pedestal 8 attached to the inside of the lower lid 4 is positioned so as to support the lower tie plate 14 of the fuel assembly 10 when the fuel assembly 10 is erected, and the weight of the fuel assembly 10 Strength to withstand

  As shown in FIG. 1, the upper tie plate 12 and the lower tie plate 14 of the fuel assembly 10 are normally fixedly supported by a fixed plate 5 or the like. By simply fixing the upper tie plate 12 and the lower tie plate 14 with the fixing plate 5 and the receiving plate 6, when vibration during transportation propagates to the fuel assembly 10, the upper tie plate 12 and the lower tie plate 14 are moved from the upper tie plate 12 to the lower tie plate 14. There may be inconveniences such as bending of the portion in which the fuel rod 11 and the water pipe (not shown) positioned between them are inserted. When the portion where the fuel rod 11 and the water pipe are inserted is bent, the fuel assembly 10 may be mechanically damaged, so that the fuel tie 11 and the lower tie plate 14 are appropriately positioned. The receiving plate 6 and the urging means 7 are provided, and the support grid 13 is supported by the receiving plate 6 and the urging means 7.

The fuel rod 11 is configured by enclosing a plurality of cylindrical fuel pellets in a long metal cladding tube. The fuel pellets are, for example, plutonium oxide (PuO ₂ ) and uranium oxide (UO ₂ ). It is formed by the MOX fuel which mixed.

  The upper tie plate 12 is provided on a surface of the grid 15 on the side opposite to the surface on which the fuel rods 11 are held, and is substantially rectangular. A handle 16 is provided on a diagonal line of the board-like grid 15 and is substantially U-shaped. The handle 16 has a pair of leg portions 17 standing on a diagonal line of the grid 15 and a tip end portion 18 connecting the pair of leg portions 17. The handle 16 is used to lift and move the fuel assembly 10, and has a buffer function for protecting the fuel rod 11 under special conditions such as the fuel holder 1 dropping, as will be described later. Therefore, the upper tie plate 12 is designed to have a strength that can sufficiently hold the load of the fuel assembly 10 and can perform a buffer function. The lower tie plate 14 supports the weight of the fuel assembly 10 during normal operation, and has a buffering function in the same manner as the upper tie plate 12 with the lower tie plate 14 alone or in combination with the lower tie plate 14 and the base 8. Therefore, the fuel assembly 10 is designed to have a strength capable of sufficiently holding the load of the fuel assembly 10 and capable of performing a buffer function.

  As an unexpected situation, for example, the fuel holder 1 falls when the fuel holder 1 is loaded into a transport container that accommodates the fuel holder 1 at a supply place, and when the transport container is transported to a demand place. Even if a transport container falls from a trailer or the like, the fuel assembly 10 needs to be protected. The fuel assembly 10 may receive a large load from the upper lid 3 and the lower lid 4 under special conditions in which the fuel holder 1 or the transport container falls. The upper tie plate 12 and the lower tie plate 14 have not only a function of bundling a plurality of fuel rods 11 while maintaining a distance, but also a buffering function for protecting the fuel rods under special conditions such as dropping of the fuel holder. When the fuel assembly 10 receives a certain load from the upper lid 3 and the lower lid 4, the upper tie plate 12 and the lower tie plate 14 are plastically deformed to reduce the energy acting on the fuel rod 11, The upper tie plate 12 and the lower tie plate 14 are configured in shape, size, material, strength, and the like so that the fuel rod 11 can be prevented from being damaged. For example, when the fuel holder 1 falls with the upper tie plate 12 down, the handle 16 receives a large load from the upper lid 3 of the fuel holder 1. When this load exceeds a certain level, the handle 16 is deformed to reduce the energy acting on the fuel rod 11 and prevent the fuel rod 11 from being damaged. By preventing the fuel rod 11 from being damaged, leakage of fuel pellets from the fuel rod 11 can be prevented.

  The buffer function of the handle 16 when the fuel holder 1 falls with the upper tie plate down will be described in detail with reference to the drawings. FIG. 3 is a schematic cross-sectional view of the main part of the fuel holder and the fuel assembly when the tip of the handle slips on the inner surface of the upper lid when the fuel holder is dropped. FIG. 3A is a cross-sectional explanatory view of main parts of the fuel holder and the fuel assembly shown in FIG. 1 when the fuel assembly collides with the inner surface of the upper cover of the fuel holder. FIG. 3B is a schematic cross-sectional view of the main part of the fuel holder and the fuel assembly obtained by cutting the fuel holder and the fuel assembly shown in FIG. 3A along a section passing through the line BB ′. FIG. 4 is a schematic cross-sectional view of the main part of the fuel holder and the fuel assembly when the tip of the handle is held at a specific position on the inner surface of the upper lid when the fuel holder is dropped. FIG. 4A is a cross-sectional explanatory view of main parts of the fuel holder and the fuel assembly when the fuel assembly collides with the inner surface of the upper cover of the fuel holder in the fuel holder and the fuel assembly shown in FIG. FIG. 4B is a schematic cross-sectional view of the main part of the fuel holder and the fuel assembly obtained by cutting the fuel holder and the fuel assembly shown in FIG. 4A along a section passing through the line segment CC ′.

  As shown in FIG. 1, the fuel assembly 10 is held in a direction orthogonal to the direction of the axis O by a fixed plate 5 and a receiving plate 6, and the fuel assembly 10 is generated by vibration from the vehicle, acceleration and braking of the vehicle, and the like. The movement in the direction of the axis O is suppressed. However, for example, under a special condition in which the fuel holder 1 or the transport container falls with the upper tie plate 12 down, the force that holds the fuel assembly 10 on the fuel holder 1 by the fixing plate 5 and the receiving plate 6. Therefore, the movement of the fuel assembly 10 in the direction of the axis O cannot be suppressed, the fuel assembly 10 moves toward the upper lid 3 with a predetermined acceleration, and the tip 18 contacts the inner surface 21. When the handle 16 receives a load from the inner surface 21 after the distal end portion 18 and the inner surface 21 come into contact with each other and becomes a certain load or more, as shown in FIGS. For example, the pair of leg portions 17 may bend in a convex shape in a direction opposite to the direction in which the tip end portion 18 slipped in a state where the tip portion 18 slips in a direction perpendicular to the longitudinal direction of the tip end portion 18.

  On the other hand, as shown in FIGS. 4 (a) and 4 (b), the tip of the fuel holder 1 moves in the direction of the axis O as described above under the special condition that the fuel holder 1 or the transport container falls. When the handle 18 receives a certain load from the inner surface 21 after the 18 has contacted the inner surface 21, the tip 18 does not slide on the inner surface 21, and the tip 18 that contacts the inner surface 21 does not slide. In a state where the position is maintained, the pair of leg portions 17 may be bent in a convex shape in the diagonal direction of the grid 15, that is, the longitudinal direction X of the distal end portion 18, and in the opposite direction to the distal end portion 18.

  As shown in FIGS. 4 (a) and 4 (b), the shock absorbing performance when the pair of leg portions 17 is deformed while maintaining the position when contacting the inner surface 21 of the tip 18 is shown in FIG. 3 (a). And as shown to (b), it is high compared with the buffering performance when a pair of leg part 17 deform | transforms in the state which the front-end | tip part 18 slipped on the inner surface 21. FIG.

  Differences in buffer performance depending on the deformation state of the handle 16 will be described with reference to a model diagram. FIG. 5 is a model diagram illustrating the relationship between the compressive displacement of the handle and the load when the tip of the handle slips on the inner surface of the upper lid when the fuel holder is dropped. FIG. 6 is a model diagram showing the relationship between the compressive displacement of the handle and the load when the tip of the handle is held at a specific position on the inner surface of the upper lid when the fuel holder is dropped.

  5 and 6, when the handle 16 receives a load from the inner surface 21 of the upper lid 3, the displacement in the direction of the axis O of the pair of legs 17 is taken as the X axis, and the direction of the axis O with respect to the pair of legs 17. The load applied to is shown on the Y axis. As shown in FIG. 5, when the handle 16 is deformed in a state where the handle 16 comes into contact with the upper lid 3 and the tip end portion 18 slides on the inner surface 21 when the fuel holder 1 is dropped, as shown in FIG. The handle 16 is deformed by a small load received by the handle 16 as compared with the case where the handle 16 is deformed in a state where the distal end portion 18 does not slide on the inner surface 21 and is held at a specific position. For example, the load required to deform the pair of leg portions 17 up to the point A shown in FIGS. 5 and 6 is the case where the handle 16 is deformed with the tip portion 18 sliding on the inner surface 21 (FIG. 5). However, this is smaller than when the handle 16 is deformed in a state where the tip 18 is held at a specific position without sliding on the inner surface 21 (FIG. 6). 5 and 6, the area surrounded by the X axis, the curve, and X = A indicates the energy required for the handle 16 to be displaced by the distance A in the direction of the axis O. Hereinafter, the energy required to deform the handle 16 may be referred to as deformation energy. The deformation energy required for the handle 16 to be displaced by the distance A in the direction of the axis O is such that the tip 18 is on the inner surface when the handle 16 is deformed with the tip 18 sliding on the inner surface 21 (FIG. 5). This is smaller than the case where the handle 16 is deformed while being held at a specific position without sliding on the surface 21 (FIG. 6).

  A part of the kinetic energy generated by the dropping of the fuel holder 1 is converted into deformation energy when the handle 16 is deformed, and the remaining kinetic energy acts on the grid 15 and the fuel rod 11. As shown in FIG. 5, if the deformation energy of the handle 16 is small, a large kinetic energy acts on the fuel rod 11 and the fuel rod 11 may be damaged. In other words, when the handle 16 is deformed in a state where the tip 18 is held at a specific position without sliding on the inner surface 21 (FIG. 6), a pair of legs against the load that the handle 16 receives from the inner surface 21 Since the reaction force of 17 is large and the load required to deform the pair of leg portions 17 becomes large, large deformation energy is absorbed. When the deformation energy required to deform the pair of leg portions 17 is large, the kinetic energy acting on the fuel rod 11 is reduced, and as a result, the fuel rod 11 can be prevented from being damaged.

  The shape, size, material, strength, and the like of the handle 16 are such that the fuel rod 11 exhibits buffering performance when the handle 16 undergoes predetermined deformation under special conditions such that the fuel holder 1 or the transport container falls. It is configured so that it can be protected. Therefore, in order to exhibit the buffering performance of the handle 16, it is necessary for the handle 16 to absorb the deformation energy assumed by the predetermined deformation. In order to absorb the deformation energy assumed when the handle is deformed, as described above, the handle 16 needs to be deformed in a state where the tip 18 is held at a specific position without sliding on the inner surface 21. . The fuel holder of the present invention absorbs the assumed deformation energy of the handle 16 when the handle 16 is deformed under a special condition that the fuel holder 1 or the transport container is dropped. The inner surface 21 of the upper lid 3 is slid on the inner surface 21 so that the inner surface 21 of the upper lid 3 is in contact with the inner surface 21 so that the handle 16 is deformed while being held at a specific position without sliding on the upper surface 21. And at least one anti-skid part to prevent. In this way, it is possible to prevent the kinetic energy more than expected from acting on the fuel rod 11, and as a result, it is possible to prevent the fuel rod 11 from being damaged.

  Next, as the upper lid in the fuel holder of the present invention, when the handle receives a load from the upper lid, a contact portion that contacts the tip of the handle and a slip prevention portion that prevents the handle from sliding on the inner surface of the upper lid are provided. An example of the upper lid will be described in detail with reference to FIGS. FIG. 7 is a schematic cross-sectional view of a main part of the fuel holder and the fuel assembly, showing an example of an upper lid in the fuel holder of the present invention. FIG. 8 is a schematic view of the inner surface of the upper lid shown in FIG. 7 as viewed from the axial direction of the fuel holder.

As shown in FIGS. 7 and 8, the fuel holder 1 of this embodiment includes a substantially square disk-shaped upper lid 3, and an inner surface 21 which is a surface of the upper lid 3 on the side where the fuel assembly 10 is accommodated, recess 22 extending over the diagonal line L ₁ of the substantially rectangular plate-shaped upper lid 3 is provided. The concave portion 22 includes a bottom surface 23 which is a contact portion with which the front end portion 18 of the handle 16 comes into contact when the handle 16 collides with the upper lid 3, and a non-sliding portion which prevents the handle 16 from sliding on the inner surface 21 of the upper lid 3. Side surfaces 24, 25, 26, and 27. Bottom surface 23 is shaped in a rectangle when viewed inner surface 21 from the axis O direction of the fuel holder 1, the long sides of the rectangular bottom 23 is arranged so as to be parallel to the diagonal line L _1. The side surfaces 24 and 25 rise vertically from the respective longitudinal edges of the bottom surface 23, and the side surfaces 26 and 27 rise vertically from the respective lateral edges of the bottom surface 23, and the bottom surface 23 and the side surfaces 24, 25, 26 and 27 form a substantially rectangular recess 22. The bottom surface 23 is formed substantially parallel to the outer surface 28 that is the surface opposite to the inner surface 21 of the upper lid 3. The upper surface 29 extending perpendicularly to the side surfaces 24, 25, 26, 27 from the end edges of the side surfaces 24, 25, 26, 27 opposite to the bottom surface 23 protrudes from the bottom surface 23 of the recess 22. Thus, it extends substantially parallel to the outer surface 28.

  The position, shape, and size of the bottom surface 23 are designed so as to include a projected image 32 obtained by projecting the distal end portion 18 of the handle 16 onto the inner surface 21 from the direction of the axis O. In this embodiment, as shown in FIG. 8, the length of the short side of the bottom surface 23 is formed to be about several millimeters longer than the length of the short side of the projection image 32, and the length of the long side of the bottom surface 23 is The projected image 32 is formed to be several tens of millimeters larger than the long side. The bottom surface 23 is preferably formed at a portion where the tip 18 may come into contact with the inner surface 21 when the fuel assembly 10 moves in the direction of the axis O when the fuel holder 1 is dropped. The side surfaces 24, 25, 26 and 27 may be formed so as to prevent the handle 16 from sliding on the inner surface 21 of the upper lid 3 when the handle 16 collides with the upper lid 3. The position, shape, and size are set as appropriate.

  Under special conditions such as the fuel holder 1 or the transport container dropping, the tip 18 of the handle 16 comes into contact with the bottom surface 23 of the upper lid 3, the handle 16 receives a load from the bottom surface 23, and the load exceeds a certain value. Then, the pair of leg portions 17 is deformed. The side surfaces 24, 25, 26, and 27 that are anti-sliding portions prevent the tip 18 that contacts the inner surface 21 from sliding on the inner surface 21, and maintain the position of the tip 18 that contacts the inner surface 21. Is formed. The side surfaces 24 and 25 prevent the tip portion 18 from sliding in the direction perpendicular to the longitudinal direction, and the side surfaces 26 and 27 prevent the tip portion 18 from sliding in the longitudinal direction. When the tip end surface of the tip end portion 18 in the axis O direction is not a flat surface but forms an inclined surface, etc., the tip portion 18 is likely to slide in one of two directions orthogonal to the longitudinal direction. May be provided with the side surface 24 or the side surface 25 on the side where the possibility of sliding is high. The upper lid 3 in this embodiment is provided with two side surfaces 24 and 25 as a sliding preventing portion so as to prevent the tip portion 18 from sliding in any direction orthogonal to the longitudinal direction. On the other hand, the possibility that the tip 18 slides in the longitudinal direction is lower than the possibility that the tip 18 slides in a direction perpendicular to the longitudinal direction. Therefore, the recess 22 may be formed in the shape of a groove extending from end to end in the diagonal direction of the substantially central portion of the inner surface 21 without providing the side surfaces 26 and 27 on the inner surface 21. Further, the recess 22 is not necessarily provided on the inner surface 21 of the upper lid 3, and when a buffer such as a plate is provided between the upper tie plate 12 and the upper lid 3, the upper tie plate of the buffer body is provided. A recess 22 is provided on the inner surface facing 12.

  In the fuel holder of the present invention, when the handle 16 collides with the inner surface 21 of the upper lid 3 and the handle 16 receives a load from the inner surface 21 of the upper lid 2 under the special condition that the fuel holder 1 or the transport container falls. As long as the inner surface 21 has the contact portion and at least one anti-sliding portion so that the tip portion 18 maintains the position of the tip portion 18 that contacts the inner surface 21 without sliding on the inner surface 21, FIGS. It is not limited to the embodiment shown. For example, as shown in FIG. 7, the side surfaces 24, 25, 26, 27 of the upper lid 3 stand up vertically from the bottom surface 23, but the side surfaces 24, 25, 26, 27 are inclined so as to spread outward from the bottom surface 23. An inclined surface may be formed, or an inclined surface inclined inward from the bottom surface 23 may be formed. Further, the side surfaces 24, 25, 26, 27 are not limited to being formed in a planar shape, and even if they are curved surfaces that draw a curve protruding inside the recess in the cross section of the recess 22 shown in FIG. It may be a curved surface in which a curve is drawn so as to protrude outward. Further, the bottom surface 23 is not limited to being formed substantially parallel to the outer surface 28, and even if it has a curved surface shape that protrudes inside the recess in the cross section of the recess 22 shown in FIG. 7, it protrudes outside the recess. It may be a curved surface that draws a curved line. The distal end surface of the distal end portion 18 is not limited to a shape that contacts the bottom surface 23 by a surface, but may be a shape that contacts a line and a point.

  Next, the operation of the fuel holder of the present invention will be described. FIG. 9A is a schematic cross-sectional view of the main part of the fuel holder and the fuel assembly, showing a state where the handle of the fuel assembly shown in FIG. 7 is deformed. FIG. 9B is a schematic cross-sectional view of a main part of the fuel holder and the fuel assembly obtained by cutting the fuel holder and the fuel assembly shown in FIG. 9A along a section passing through the line EE ′.

As shown in FIG. 9, when the tip 18 of the handle 16 comes into contact with the bottom surface 23 of the upper lid 3 under a special condition in which the fuel holder 1 or the transport container falls, the handle 16 applies a load from the inner surface 21 of the upper lid 2. At the same time, a force is applied to slide the tip 18 in a direction perpendicular to the longitudinal direction. The tip 18 contacts one of the side surface 24 or the side surface 25 and receives a reaction force from the side surface 24 or the side surface 25, so that the sliding force of the tip portion 18 is equal to the reaction force from the side surface 24 or 25. The part 18 is held in contact with the inner surface 21 thereof. In a state where the tip 18 is held in the position in contact with the inner surface 21, further handle 16 receives a load, at a load exceeding a certain value, a pair of leg portions 17 meet the longitudinal direction X ₁ of the tip 18 Thus, it bends in a convex shape toward the side opposite to the direction in which the tip 18 is present, and begins to deform. The kinetic energy generated by the drop of the fuel holder 1 is absorbed by converting a part of the pair of leg portions 17 into deformation energy. Although the kinetic energy that has not been absorbed acts on the grid 15 and the fuel rods 11, the pair of leg portions 17 is deformed in a state in which the tip portion 18 is kept in contact with the inner surface 21, so that the assumed deformation energy is reduced. By being absorbed, it is possible to prevent the kinetic energy more than expected from acting on the grid 15 and the fuel rod 11, and as a result, it is possible to prevent the fuel rod 11 from being damaged.

Incidentally, in this embodiment, when the handle 16 is subjected to a load from the inner surface 21 of the top cover 2, a longitudinal direction X ₁ of the pair of leg portions 17 tip 18, the direction in which there is the tip portion 18 Is bent in a convex shape toward the opposite side, but as long as the pair of leg portions 17 is deformed in a state where the position of the tip end portion 18 in contact with the inner surface 21 is maintained, the way of deforming the pair of leg portions 17 is particularly limited not, to a pair of legs 17 may be bent into a wave shape in the longitudinal direction X ₁ of the tip portion 18 may be bent in a direction perpendicular to the longitudinal direction X _1. However, it is preferable that the pair of leg portions 17 receive a load evenly and undergo almost the same deformation.

  Next, an example of a method for using the fuel holder 1 and a method for transporting the fuel assembly 10 will be described.

  The fuel holder 1 is placed vertically so that the longitudinal direction thereof is the vertical direction, the side of the housing shell 2 is opened, and the fuel assembly 10 is disposed in the housing shell 2. At this time, the handle 16 is held by a lifting tool (not shown), the fuel assembly 10 is lifted and placed in the housing shell 2, and the receiving plate 6 or the fixing plate 5 and the upper tie plate 12, the receiving plate 6 or the biasing means 7. And the support grid 13, the receiving plate 6 or the fixed plate 5, and the lower tie plate 14 are arranged so as to contact each other.

  As shown in FIG. 2, the housing shell 2 is formed by four side walls 41, 42, 43, 44. After the fuel assembly 10 is arranged on the housing shell 2, the four side walls 41, 42, 43 are formed. 44 are fixed in a state of being orthogonal to each other. In the housing shell 2 before the fuel assembly 10 is disposed, the side walls 41, 42, 43, 44 may or may not be fixed to each other. In other words, the housing shell 2 before the fuel assembly 10 is disposed has, for example, a mode in which the side walls 41, 42, 43, 44 are separated from each other, and the side walls 41, 42 and the side walls 43, 44 that are adjacent to each other. A mode in which two side walls are fixed, a mode in which the side walls 41, 42, 43 are fixed and only the side wall 44 is separated, and four side walls 41, 42, 43, 44 are orthogonal to each other Any of the fixed aspects may be used.

  Next, an upper lid 3 and a lower lid 4 are respectively attached to both end portions of the housing shell 2 so as to close both end openings of the housing shell 2, and the lower lid is placed on the bottom surface of the lower tie plate 14 as shown in FIG. 4 is brought into contact with the base 8. As shown in FIGS. 7 and 8, the upper lid 3 is attached to the end of the housing shell 2 so that the bottom surface 23 includes the entire projection image 32 of the handle 16. In this embodiment, the bottom surface 23 and the tip portion 18 are provided with a gap therebetween, but may be designed so that the bottom surface 23 and the tip portion 18 abut. At this time, when a hard plate material is attached to the inner surface 21 of the upper lid 3 via an elastic body, the recess 22 including the bottom surface 23 is provided on the surface of the hard plate material on the fuel assembly 10 side. If the bottom surface 23 and the front end portion 18 are in contact with each other, there is a possibility that the front end portion 18 may contact the inner surface 21 obliquely with respect to the axis O direction under a special condition that the fuel holder 1 or the transport container falls. Since it becomes low, it becomes difficult for the contact tip 18 to cause skidding on the inner surface 21. Further, when the tip 18 is on the fuel assembly 10 side with respect to the upper surface 29, the tip 18 moves obliquely with respect to the direction of the axis O when the fuel holder 1 is dropped, and is displaced from the recess 22 to contact the upper surface 29. The restraint from the side surface 24 or the side surface 25 is not received, there is a possibility that the tip portion 18 slides in a direction shifted from the longitudinal direction and bends in a direction opposite to the slipping direction. In the embodiment of the upper lid shown in FIGS. 10 and 11 to be described later, the same applies to the case where the tip 518 is on the fuel assembly side from the tip of the projection 551 or the projection 552. Accordingly, as shown in FIGS. 7 and 8, 10 and 11, the bottom surface 23 provided on the inner surface 21 and the contact portion 555 provided on the inner surface 521 are configured such that the tip 18 is the recess 22 and the contact portion 555 when the fuel holder 1 is dropped. In consideration of the possibility that the upper surfaces 29 and 529 may come out of contact with each other, the dimensions may be larger than the projection surfaces 32 and 532. However, if the bottom surface 23 and the tip end portion 18 are designed to come into contact with each other, there is no need to consider such a shift during dropping, and the bottom surface 23 and the contact portion 555 have the same dimensions as the tip end portions 18 and 518. It may be about or slightly larger. Further, even if the depth of the concave portion 22 is small, the distal end portion 18 is surely restrained by the side surface 24 or the side surface 25, and even if the height of the convex portions 551, 552 is small, the distal end portion 518 is surely the convex portion 551 or convex portion. It is restrained by 552 and can slide in the direction shifted from the longitudinal direction of the tip end portions 18 and 518, and can be prevented from bending in the direction opposite to the sliding direction.

  The fuel holder 1 in which the fuel assembly 10 is accommodated is further loaded into a transport container, and is transported to a demand place such as a nuclear power plant and other nuclear fuel facilities by transport means such as a trailer or a ship. At this time, the hanger 45 (see FIG. 1) in the fuel holder 1 in which the fuel assembly 10 is accommodated is lifted by a hanger (not shown) and loaded into a transport container (not shown). The number of fuel holders 1 loaded in one transport container differs depending on the type of transport container, and examples thereof include 4, 9, 12 and the like. The fuel holder 1 of the present invention is transported by a conventionally known transport container. Is done.

  According to the method of using the fuel holder 1, the handle 16 is attached to the inner surface of the upper lid 3 even if an unexpected situation occurs such that the fuel holder 1 falls when the fuel holder 1 is transported to the transport container that houses the fuel holder 1. When a load is received from 21, the pair of leg portions 17 is deformed in a state where the position of the tip end portion 18 in contact with the inner surface 21 is maintained. Therefore, the grid 15 and the fuel rod are absorbed by absorbing the assumed deformation energy. It is possible to prevent kinetic energy more than expected from acting on the fuel rod 11, and as a result, damage to the fuel rod 11 can be prevented.

  According to this method for transporting the fuel assembly 10, an unexpected situation in which the fuel holder 1 falls when the fuel holder 1 is loaded into the transport container that houses the fuel holder 1, the transport container in which the fuel holder 1 is housed. Even if an unforeseen situation such as the fuel holder 1 falling when transporting the transport container to the trailer, or an unforeseen situation such as the transport container falling from the trailer or the like when transporting the transport container to the demand place, When the handle 16 of the fuel assembly 10 receives a load from the inner surface 21 of the upper lid 3 of the fuel holder 1, the pair of leg portions 17 is deformed in a state in which the position of the tip 18 contacting the inner surface 21 is maintained. By absorbing the assumed deformation energy, it is possible to prevent the kinetic energy more than expected from acting on the grid 15 and the fuel rod 11, and as a result, the fuel rod 11 can be prevented from being damaged. Can.

Next, a second embodiment of the upper lid 3 in the fuel holder 1 described above will be described with reference to the drawings.
FIG. 10 is a schematic cross-sectional view of a main part of the fuel holder and the fuel assembly, showing an example of an upper lid in the fuel holder of the present invention. FIG. 11 is a schematic view of the inner surface of the upper lid shown in FIG. 10 as viewed from the axial direction of the fuel holder.

  The upper cover 503 of the second embodiment shown in FIGS. 10 and 11 is in common with the upper cover 3 of the first embodiment shown in FIGS. 7 and 8 under special conditions such as dropping of the fuel holder. When the handle 516 receives a load from the inner surface 521 of the upper lid 503, the inner surface 521 holds the position of the tip 516 of the handle 516 and the handle so that the position of the tip 516 contacting the inner surface 521 is maintained. 516 has a sliding prevention part which prevents 516 from sliding on the inner surface 521.

As shown in FIGS. 10 and 11, the fuel holder 501 of this embodiment includes a substantially square disk-shaped upper lid 503, and an inner surface 521 that is a surface of the upper lid 503 on the side where the fuel assembly 510 is accommodated, When the handle 516 receives a load from the inner surface 521 of the upper lid 503 under a special condition such as the fuel holder 501 dropping, the contact portion 555 that the tip 518 of the handle 516 contacts and the handle 516 on the inner surface 521 And four convex portions 551, 552, 553, and 554, which are anti-sliding portions that prevent sliding. The four convex portions 551, 552, 553, and 554 have a rectangular parallelepiped shape that stands upright on the inner surface 521 in a direction perpendicular to the planar inner surface 521, and have the same size and shape. Are arranged in line symmetry with respect to the diagonal line _{L 3} in the two protrusions 551 and 552 and two protrusions 553, 554 Togaryaku square plate-shaped upper lid 503, whereas the two protrusions 551 and two protrusions are disposed respectively axisymmetrically other against the diagonal _{L 4} are the 552 and 553. The contact portion 555 is formed substantially parallel to the outer surface 528 that is the surface opposite to the inner surface 521 of the upper lid 3.

  As shown in FIGS. 10 and 11, the upper surface 529 and the contact portion 555 which are surfaces of the inner surface 521 excluding the convex portions 551, 552, 553, 554 and the contact portion 555 are on the same plane. Therefore, in this embodiment, the boundary between the contact portion 555 and the upper surface 529 is not clear, but the contact portion 555 includes the entire projection image 532 obtained by projecting the tip end portion 518 onto the inner surface 521 from the axis O direction. That is, it is a long region sandwiched between the convex portions 551 and 552 and the convex portions 553 and 554, and has an area slightly larger than the projected image 532.

  The fuel holder of the present invention is not limited to the embodiment shown in FIGS. For example, the convex portions 551, 552, 553, and 554 of the upper lid 503 shown in FIGS. 10 and 11 have a rectangular parallelepiped shape that stands upright in the vertical direction with respect to the inner surface 521, but are not limited to a rectangular parallelepiped shape, but are a cylindrical shape and a triangular prism shape. The shape may be a polygonal column shape, a shape in which the diameter of the head is expanded, a shape in which the diameter of the bottom is expanded, or the like.

Further, when the tip 518 is highly likely to slide in one of the two directions orthogonal to the longitudinal direction, the protrusions 551 and 554 or the protrusions 552 and 553 are provided on the side that is likely to slip. Good. In this embodiment, two convex portions 551 and 554 and convex portions 552 and 553 are provided in the respective directions orthogonal to the longitudinal direction of the tip portion 518, but the number of convex portions is not particularly limited. There may be more than one. In this embodiment, the convex portions 551 and 552 and the convex portions 553 and 554 are arranged symmetrically with respect to the diagonal line L ₃ , but the tip portion 518 can be prevented from sliding on the inner surface 521. as long as the arrangement of the four protrusions 551,552,553,554 is not particularly limited, and the center and the convex portion 552 of the convex portion 551 and the convex portion 554 is disposed in line symmetry with respect to the diagonal line _{L 3} Good. Also. Since the possibility that the tip end portion 18 slides in the longitudinal direction is lower than the possibility that the tip end portion 18 slides in a direction perpendicular to the longitudinal direction, in this embodiment, a convex portion is formed outside the short side of the projection image 532. Although not provided, a convex portion may be provided outside the short side of the projection image 532.

  In this embodiment, the contact portion 555 is flush with the upper surface 529, but the thickness of the contact portion 555 from the outer surface 528 may be larger or smaller than the thickness of the upper surface 529 from the outer surface 528. Also good. Further, the contact portion 555 is not limited to be formed in a flat shape, and may be a curved surface that draws a curve protruding in the direction in which the fuel assembly 510 is disposed in the cross section of the contact portion 555 shown in FIG. It may be a concave curved surface that draws a curve protruding in the opposite direction. Further, the upper surface 529 is not limited to being formed substantially parallel to the outer surface 528, and is a curved surface that draws a curve protruding in the direction in which the fuel assembly 510 is disposed in the cross section of the contact portion 555 shown in FIG. Alternatively, it may be a concave curved surface that draws a curve protruding in the opposite direction.

  FIG. 12A is a schematic cross-sectional view of the main part of the fuel holder and the fuel assembly, showing a state in which the handle of the fuel assembly shown in FIG. 10 is deformed. FIG. 12B is a schematic cross-sectional view of the main part of the fuel holder and the fuel assembly obtained by cutting the fuel holder and the fuel assembly shown in FIG. 12A along a section passing through the line segment FF ′.

As shown in FIG. 12, when the tip 518 of the handle 516 comes into contact with the contact portion 555 of the upper lid 503 under a special condition that the fuel holder 501 or the transport container falls, the handle 516 is loaded from the inner surface 521 of the upper lid 503. At the same time, a force is applied to slide the tip 518 in a direction perpendicular to the longitudinal direction. The tip 518 is in contact with one of the protrusions 551, 552 or the protrusions 553, 554, receives the reaction force from the protrusions 551, 552 or the protrusions 553, 554, and the force by which the tip 518 slips and the protrusion 551 Since the reaction force from 552 or the convex portions 553 and 554 becomes equal, the tip portion 518 is held at the contacted position on the inner surface 521 thereof. When the tip 518 is held at a position in contact with the inner surface 521, the handle 516 further receives a load, and when the load exceeds a certain value, the pair of legs 517 are moved in the longitudinal direction X ₂ of the tip 518. Then, it bends in a convex shape toward the side opposite to the direction in which the tip portion 518 exists, and starts to deform. The kinetic energy generated by the dropping of the fuel holder 501 is absorbed by converting a part of the pair of leg portions 517 into deformation energy. Although the kinetic energy that has not been absorbed acts on the grid 515 and the fuel rod 511, the deformation energy that is assumed is reduced by the pair of leg portions 517 being deformed in a state where the tip portion 518 is in contact with the inner surface 521. By being absorbed, it is possible to prevent the kinetic energy more than expected from acting on the grid 15 and the fuel rod 11, and as a result, it is possible to prevent the fuel rod 11 from being damaged.

Incidentally, in this embodiment, when the handle 516 is subjected to a load from the inner surface 521 of the upper cover 502, and the direction the pair of leg portions 517 is a longitudinal _{X 2} of the distal end portion 518, there is a tip 518 Is bent in a convex shape toward the opposite side. However, as long as the pair of leg portions 517 is deformed in a state where the position of the tip end portion 518 in contact with the inner surface 521 is maintained, the way of deforming the pair of leg portions 517 is particularly limited not, to a pair of leg portions 517 may be bent into a wave shape in the longitudinal direction X ₂ of the distal end portion 518 may be bent in a direction perpendicular to the longitudinal direction X _2. However, it is preferable that the pair of leg portions 517 receive a load evenly and undergo almost the same deformation.

Next, a third embodiment of the upper lid 3 in the fuel holder 1 described above will be described with reference to the drawings.
FIG. 13 is a schematic cross-sectional view of a main part of a fuel holder and a fuel assembly, showing an example of an upper lid in the fuel holder of the present invention. FIG. 14 is a schematic view of the inner surface of the upper lid shown in FIG. 13 as viewed from the axial direction of the fuel holder.

  The upper cover 603 of the third embodiment shown in FIGS. 13 and 14 is the same as the upper cover 3 of the first embodiment shown in FIGS. 7 and 8 and the upper cover 503 of the second embodiment shown in FIGS. 10 and 11. The inner surface is held so that the position of the tip 616 in contact with the inner surface 621 is maintained when the handle 616 receives a load from the inner surface 621 of the upper lid 603 under special conditions such as dropping of the fuel holder. Reference numeral 621 denotes a point having a contact portion where the tip end portion 618 of the handle 616 contacts and a slip prevention portion which prevents the handle 616 from sliding on the inner surface 621.

As shown in FIGS. 13 and 14, the fuel holder 601 of this embodiment includes a substantially square disk-shaped upper lid 603, and an inner surface 621 that is a surface of the upper lid 603 on the side where the fuel assembly 610 is accommodated When the handle 616 receives a load from the inner surface 621 of the upper lid 603 under special conditions such as the holder 601 dropping, the contact portion 655 that the tip 618 of the handle 616 contacts and the handle 616 moves on the inner surface 621. It has two guide plates 651 and 652 which are anti-sliding portions for preventing slipping. The two guide plates 651, 652, rises from the inner surface 621 in the direction of the axis O, that is, square-shaped upstanding perpendicularly from planar interior surface 621, along the diagonal L ₅ of substantially rectangular plate-shaped upper lid 603 extending Exist. The length of the guide plates 651 and 652 in the direction of the axis O is configured to be larger than the gap provided between the tip 618 and the inner surface 621, that is, the length in the axis O direction between the tip 618 and the inner surface 621. Yes. Therefore, the guide plates 651 and 652 have a function of guiding the fuel assembly 610 to move in the direction of the axis O and to contact the contact portion 655 when the fuel holder 601 falls. Diagonal L ₅ direction length of the guide plates 651 and 652 are configured such that the longitudinal direction substantially the same as the length of the tip 618. Guide plates 651 and 652 are formed so that the direction of thickness perpendicular to the diagonal line _{L 5} in the guide plate 651 and 652 is the smallest, is formed in a square plate shape extending in the direction of the axis O and the diagonal _{L 5} direction. Two guide plates 651 and 652 are arranged in line symmetry with respect to the diagonal line _{L 5} in a substantially rectangular plate-shaped upper lid 603. The contact portion 655 is formed substantially parallel to the outer surface 628 that is the surface opposite to the inner surface 621.

  As shown in FIGS. 13 and 14, the upper surface 629 and the contact portion 655 which are surfaces of the inner surface 621 excluding the two guide plates 651 and 652 and the contact portion 655 are on the same plane. Therefore, in this embodiment, the boundary between the contact portion 666 and the upper surface 629 is not clear, but the contact portion 655 includes an entire projection image 632 obtained by projecting the tip end portion 618 onto the inner surface 621 from the direction of the axis O. That is, it is a long region sandwiched between the two guide plates 651 and 652 and has an area slightly larger than the projected image 632.

The fuel holder of the present invention is not limited to the embodiment shown in FIGS. For example, the guide plates 651 and 652 of the upper lid 603 shown in FIG. 13 have a square plate shape that stands upright in the vertical direction with respect to the inner surface 521, but are not limited to a square plate shape, but a disc shape, semi-disc shape, or polygonal shape. It may be a plate shape, a rod shape, a tube shape or the like. Also, the diagonal _{L 5} length of the guide plate 651 and 652 may be larger or smaller than the longitudinal length of the distal portion 618.

  In addition, when there is a high possibility that the distal end portion 618 slides in one of two directions orthogonal to the longitudinal direction, the guide plates 651 and 652 may be provided on the side where the possibility of sliding is high. In this embodiment, the guide plates 651 and 552 are provided in the respective directions orthogonal to the longitudinal direction of the distal end portion 618, but the number of guide plates is not particularly limited, and may be three or more.

  In this embodiment, the contact portion 655 is flush with the upper surface 629, but the thickness of the contact portion 655 from the outer surface 628 may be larger or smaller than the thickness of the upper surface 629 from the outer surface 628. Also good. Further, the contact portion 655 is not limited to be formed in a planar shape, and may be a curved surface that draws a curve protruding in the direction in which the fuel assembly 610 is disposed in the cross section of the contact portion 655 shown in FIG. It may be a concave curved surface that draws a curve protruding in the opposite direction. Further, the upper surface 629 is not limited to being formed substantially parallel to the outer surface 628, and is a curved surface that draws a curve protruding in the direction in which the fuel assembly 610 is disposed in the cross section of the contact portion 655 shown in FIG. Alternatively, it may be a concave curved surface that draws a curve protruding in the opposite direction.

  FIG. 15A is a schematic cross-sectional view of the main part of the fuel holder and the fuel assembly, showing a state in which the handle of the fuel assembly shown in FIG. 13 is deformed. FIG. 15B is a schematic cross-sectional view of the main part of the fuel holder and the fuel assembly obtained by cutting the fuel holder and the fuel assembly shown in FIG. 15A along a section passing through the line GG ′.

As shown in FIG. 15, the fuel assembly 610 moves toward the upper lid 603 under a special condition such that the fuel holder 601 or the transport container falls, and the tip 618 of the handle 616 moves to the contact portion 655 of the upper lid 603. Contact. At this time, since the length of the guide plates 651 and 652 in the direction of the axis O is larger than the distance between the contact portion 655 and the tip surface of the tip portion 618, the guide plates 651 and 652 move the handle 616 in the direction of the axis O. The function of guiding the contact portion 655 so as to come into contact is achieved. That is, even if the handle 616 moves obliquely with respect to the axis O direction and contacts one of the guide plates 651 or 652, the handle 616 receives the reaction force from the guide plate 651 or 652, so that the handle 616 is guided by the guide plates 651 and 652. Guided to move in the space surrounded by. When the handle 616 comes into contact with the contact portion 655, the handle 616 receives a load from the inner surface 621 of the upper lid 603, and at the same time, a force that the tip end portion 618 slides in a direction perpendicular to the longitudinal direction acts. The tip 618 contacts one of the guide plates 651 or 652 and receives a reaction force from the guide plate 651 or 652, and the sliding force of the tip 618 and the reaction force from the guide plate 651 or 652 become equal to each other. Part 618 is held in contact on its inner surface 621. In a state where the top portion 618 is held in the position in contact with the inner surface 621, further handle 616 under load, it becomes load exceeding a certain value, a pair of leg portions 617 meet the longitudinal direction X ₃ of the distal end portion 618 Thus, it bends in a convex shape toward the side opposite to the direction in which the tip portion 618 exists and starts to deform. The kinetic energy generated by the dropping of the fuel holder 601 is absorbed by converting a part of the pair of leg portions 617 into deformation energy. Although the kinetic energy that has not been absorbed acts on the grid 615 and the fuel rod 611, the deformation energy that is assumed is reduced when the pair of legs 617 is deformed while the tip 618 is kept in contact with the inner surface 621. By being absorbed, it is possible to prevent the kinetic energy more than expected from acting on the grid 15 and the fuel rod 11, and as a result, it is possible to prevent the fuel rod 11 from being damaged.

Incidentally, in this embodiment, when the handle 616 is subjected to a load from the inner surface 621 of the upper cover 602, and the direction the pair of leg portions 617 is a longitudinal _{X 3} of the tip portion 618, there is a tip 618 Is bent in a convex shape toward the opposite side, but as long as the pair of leg portions 617 is deformed in a state where the position of the tip end portion 618 in contact with the inner surface 621 is maintained, the way of deforming the pair of leg portions 617 is particularly limited not, to a pair of leg portions 617 may be bent into a wave shape in the longitudinal direction X ₃ of the tip portion 618 may be bent in a direction perpendicular to the longitudinal direction X _3. However, it is preferable that the pair of leg portions 617 receive a load evenly and undergo almost the same deformation.

DESCRIPTION OF SYMBOLS 1,501 Fuel holder 2,502 Housing shell 3,503 Upper lid 4 Lower lid 5 Fixing plate 6 Receiving plate 7 Energizing means 8 Base 10, 510 Fuel assembly 11,511 Fuel rod 12 Upper tie plate 13 Support grid 14 Lower type Rate 15, 515 Grid 16, 516 Handle 17, 517 Leg 18, 518 Tip 21, 521 Inner surface 22 Recess 23 Bottom 24, 25, 26, 27 Side 28, 528, 628 Outer surface 29, 529, 629 Upper surface 30, 551 , 552, 553, 554 Convex part 32, 532, 632 Projection image 41, 42, 43, 44 Side wall 45 Suspended tool 555, 655 Contact part 651, 652 Guide plate

Claims (10)

A grid that holds the tip of the fuel rod, and a pair of legs that are provided on a surface of the grid opposite to the surface on which the fuel rod is held and that stand on the diagonal of the substantially square disk-shaped grid And a fuel holder that closes one end opening of the housing shell with an upper lid capable of housing a fuel assembly having a substantially U-shaped handle having a tip and a tip portion connecting the pair of legs,
When the handle receives a load from the inner surface of the upper lid, the inner surface is in contact with the tip and the handle is on the inner surface so that the position of the tip is in contact with the inner surface. A fuel holder, comprising: a sliding prevention portion that prevents sliding.   The fuel holder according to claim 1, wherein a concave portion is formed by the contact portion and the slip prevention portion.   3. The fuel holder according to claim 2, wherein the concave portion is provided so as to include a projection image obtained by projecting the tip portion onto the inner surface from an axial direction of the fuel assembly.   The fuel holder according to claim 3, wherein the recess extends in a longitudinal direction of the projected image.   The fuel holder according to claim 1, wherein the anti-sliding portion is a convex portion.   The fuel holder according to claim 5, wherein the convex portion extends in a longitudinal direction of a projection image obtained by projecting the tip end portion from the axial direction of the fuel assembly onto the inner surface.   The anti-sliding portion is a guide plate that rises in the axial direction from the inner surface, and a gap is provided between the tip and the inner surface, and the axial length of the guide plate is larger than the axial length of the gap. The fuel holder according to claim 1.   The fuel holder according to any one of claims 1 to 6, wherein when the fuel assembly is accommodated, the tip end portion abuts on the inner surface.   A method for using a fuel holder, wherein the fuel assembly is accommodated in the fuel holder according to any one of claims 1 to 8.   A method for transporting a fuel assembly, wherein the fuel assembly is accommodated in the fuel holder according to any one of claims 1 to 8 and transported.

Images