JP2016191569A - Cask basket - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce costs without using welding for manufacture of a square pipe.SOLUTION: In a cask basket, a bundle body 11 is formed by disposing a plurality of square pipes 40 while respective sides face one another. In the square pipes 40, a pair of first long plate members 41 opposing each other, and a pair of second long plate members 42 opposing each other are assembled on a rectangular cross section via a coupling part 20, both the long edges of the second long plate members 42 are flush with and project from both the long edges of the first long plate members 41 in four corners of the square pipes 40, respectively, and a storage part 13 for storing a neutron absorbing member is formed between both the long edges opposing each other.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a cask basket used for transporting and storing spent nuclear fuel assemblies.

  Since the spent nuclear fuel assembly taken out from the nuclear reactor is in a state of emitting radiation and generating decay heat, a dedicated container called a cask is used for transporting and storing the spent nuclear fuel assembly. The cask has a function of shielding radiation and a function of suppressing an excessive temperature rise due to decay heat, and a sufficient strength is required so as not to be damaged.

  In order to secure these functions, for example, as shown in FIG. 9, the cask has a square pipe 101 that accommodates fuel rods, a bundle 111 composed of a bundle of square pipes 101, and a body 112 that protects the bundle 111. , A neutron shield 113 that covers the fuselage 112 and shields neutron radiation, an outer casing 114 that covers the outermost periphery and has heat-dissipating fins, and a shock absorber that is housed at both ends to absorb the impact of falling. 115.

JP-A-2-293698 JP 2008-96149 A

  Conventionally, as a manufacturing method of a square pipe constituting a basket, a steel plate material, a stainless steel plate material, and an aluminum alloy plate material are bent and formed into a rectangular cross section and joined by welding, or two channel-shaped cross-section molding materials Are generally joined by butt welding to form a rectangular cross section. However, if there is poor welding, the strength of the square pipe is impaired, causing damage. Therefore, when a square pipe is manufactured by welding, an inspection is required to confirm the welding state. As described above, the square pipe manufactured by welding takes a long time for manufacturing and inspection, which causes a manufacturing cost.

  Moreover, the method of shape | molding a square pipe without welding is disclosed by patent document 2, for example. As shown in FIG. 10, the present invention uses a square pipe body 106 made of pultruded aluminum alloy. The square pipe body 106 is formed with an accommodation space 108 for accommodating the neutron absorbing member 107. According to the invention disclosed in Patent Document 2, although welding is not required and a period of inspection or the like is shortened, the square pipe body 106 itself has a complicated cross-sectional shape, and accuracy during pultrusion is required. If it is low, correction and fixing are required, which may increase the production cost.

  An object of this invention is to provide the basket for casks which can reduce a manufacturing cost without using welding by assembling a square pipe via a connection part.

In order to achieve this object, the invention according to claim 1
A cask basket in which a bundle of square pipes is formed by arranging the side surfaces of a plurality of square pipes facing each other,
In the square pipe, a pair of first long plate members opposed to each other and a pair of second long plate members opposed to each other are assembled into a rectangular cross section via a coupling portion,
At the four corners of the square pipe, the two long edges of the second long plate member protrude from the two long edges of the first long plate member to be flush with each other. In addition, an accommodating portion for accommodating the neutron absorbing member is formed.

The invention according to claim 2 is a cask basket according to claim 1,
The joint is
A plurality of claw portions that are projected at predetermined intervals on both long edge portions of the first long plate member, and a collar portion is formed on one end portion in the length direction;
A plurality of slits formed on both long edge portions of the second long plate member and engaged with the claw portions, respectively;
A fixing piece that is engaged with the other of the slits in the length direction, and that presses the collar portion of the claw portion against one end portion in the length direction of the slit to prevent the claw portion from coming off from the slit. It is characterized by that.

The invention according to claim 3 is a cask basket according to claim 2,
The bundled square pipes are arranged with adjacent square pipes rotated 90 degrees around the axis,
The accommodating portion is closed by a first long plate member of an adjacent square pipe.

The invention according to claim 4 is a cask comprising the basket according to any one of claims 1 to 3,
A plurality of block bodies having a substantially fan-shaped cross section arranged at predetermined intervals on the outer periphery of the bundle body,
And a plurality of band members fastened between the two block bodies arranged in the circumferential direction to restrain the bundle.

The invention according to claim 5 is a cask according to claim 4,
The component of the square pipe is made of carbon steel or carbon steel alloy steel,
The block body is made of an aluminum alloy.

  According to the first aspect of the present invention, the square pipe is assembled by engaging the first long plate member and the second long plate member via the engaging portion, so that welding is unnecessary and the production period is shortened. This can reduce the manufacturing cost. In addition, with a simple structure in which the second long plate member protrudes from both edges of the first long plate member at the four corners of the square pipe, it is possible to form the accommodating portion of the neutron absorbing member, thereby reducing the manufacturing cost. Can contribute.

  According to the invention of claim 2, the claw portion formed on the first long plate member is engaged with the slit formed on the second long plate member, and the fixing piece is fitted and fixed to the slit. By assembling the square pipe by preventing the claw from coming off from the slit, it is possible to form a high-strength square pipe by simply fastening the four long plate members with a simple structure. Can be reduced.

  According to the invention of claim 3, the plurality of square pipes can be closed by alternately arranging the square pipes rotated by 90 ° around the axis, and the neutron absorbing member can be stabilized in the storage part. Can be accommodated.

  According to the invention which concerns on Claim 4, since several block bodies are arrange | positioned in the outer peripheral part of a bundle body, these block bodies are connected by a band member, and the outer peripheral part of a bundle body is restrained, Therefore The bundle can be reliably held without suppressing the stress in the circumferential direction.

  According to the invention according to claim 5, by forming the square pipe from carbon steel or carbon steel alloy steel, the strength of the bundle can be secured, and the block body is made of an aluminum alloy. The thermal conductivity of the basket can be increased. Furthermore, a bundle of square pipes having a relatively small coefficient of thermal expansion is surrounded by a plurality of blocks having a relatively large coefficient of thermal expansion, and the blocks are constrained by a band member so that the radial direction due to decay heat The bundle can be securely held by absorbing the thermal expansion of the.

It is a top view which shows the basket for casks based on embodiment of this invention. (A) And (b) is a front view of a long plate member, respectively, (a) shows a 1st long plate member, (b) shows a 2nd long plate member. It is a disassembled perspective view of a square pipe. (A)-(f) shows the connection procedure of the coupling | bond part of a long plate member, (a)-(c) is sectional drawing of planar view, (d)-(f) is partial sectional drawing of side view. . (A) And (b) is sectional drawing of planar view of a square pipe, (a) shows an exploded state, (b) shows an assembly state. (A) And (b) is sectional drawing of the planar view which shows the assembly state of two square pipes, (a) shows an exploded state, (b) shows an assembly state. It is a partially cutaway perspective view showing the assembled bundle. It is a partially exploded plan view which shows the attachment state of the band member of a basket. It is a partial cross section perspective view which shows the structure of the conventional cask. It is a perspective view which shows the square pipe which comprises some conventional cask baskets.

An overall configuration of a cask basket 10 according to the present invention will be described with reference to FIGS.
As shown in FIGS. 1 and 5, a cask basket (hereinafter simply referred to as a basket) 10 includes a plurality of square pipes 40 that contain spent nuclear fuel assemblies, and each side surface thereof is disposed facing each other. A bundle 11 is formed. As shown in FIG. 2, the square pipe 40 includes a pair of first long plate members 41 arranged to face each other and a pair of second long plate members 42 arranged to face each other. 3 and a plurality of connecting portions 20 shown in FIG. 4 are assembled into a rectangular (square) cross section. And in the four corners of the square pipe 40, the two long edge portions of the second long plate member 42 protrude from the long edge portions of the first long plate member 41 in a flush manner, and are opposed to each other. An accommodating portion 13 that accommodates the neutron absorbing member 12 is formed between both long edge portions of the member 42.

  As shown in FIG. 6, the bundle body 11 is arranged such that adjacent square pipes 40 are rotated 90 degrees around the axis. Each accommodating portion 13 that accommodates the neutron absorbing member 12 is closed by the first long plate member 41 of the adjacent square pipe 40. Thereby, the neutron absorption member 12 can be accommodated stably.

  And on the outer periphery of the bundle 11, a plurality of large and small two types of block bodies 14A, 14B having a large and small size are provided at predetermined intervals, and in the figure, four block bodies 14A, 14B are arranged, a total of eight, The band member 44 is fastened between the adjacent large block bodies 14A, and the outer peripheral portion of the bundle body 11 is restrained.

  Here, the constituent members of the square pipe 40 are made of, for example, carbon steel, and the first long plate member 41 and the second long plate member 42 are made of, for example, SGV having higher thermal conductivity than stainless steel, By interposing the neutron absorbing member 12 made of an aluminum alloy containing a boron compound, the strength is ensured together with the heat removal performance. The block bodies 14A and 14B are made of an aluminum alloy having a high thermal conductivity.

Here, the detail of the coupling | bond part 20 of the square pipe 40 is demonstrated with reference to FIGS.
As shown in FIGS. 2 and 3, the first long plate member 41 is a long plate material. A plurality of the long plate members are spaced at predetermined intervals on both long edge portions, and four nails are shown in the drawing, for a total of eight claws. The parts 15 are projected in a flush manner. A hook 16 is formed at one end of the claw portions 15 in the length direction, in the drawing, at the lower end. These flange portions 16 are configured by a tapered surface inclined upward from the outer end portion toward the center portion. In addition, rectangular cutout portions 18 for fitting fixing pieces 43 described later are formed above the claw portions 15. A screw hole 19 is formed in the back side of the notch 18.

  On the other hand, on both long edges of the second long plate member 42, a plurality of slits 21 in the length direction with which the claw portions 15 are respectively engaged are formed at predetermined intervals. At the lower end portions of these slits 21, tapered locking surfaces 22 that are inclined upward from the front surface to the back surface are formed in order to prevent the flange portion 16 from coming off.

  And the fixing piece 43 for fastening the 1st long plate member 41 and the 2nd long plate member 42 firmly is provided while preventing the collar part 16 from slipping out. These fixed pieces 43 are plate materials having the same thickness as the first long plate member 41, and the front end side is bent into a crank shape corresponding to the thickness, and an engagement portion 43 a to be engaged with the upper end side of the slit 21 is formed. The The engaging portion 43a is formed so that the protruding width thereof is the same as the thickness of the second long plate member 42, and even if the engaging portion 43a is engaged with the slit 21 from the back side, the second long plate member 42 on the opposite side is engaged. It does not protrude from the surface. In addition, a through hole 43 b that matches the screw hole 19 in a state of being fitted to the slit 21 is formed in the base end surface of the fixed piece 43. Therefore, the hook portion 16 is pressed against the locking surface 22 of the slit 21 by fitting the claw portion 15 into the slit 21 and fitting the engaging portion 43 a of the fixed piece 43 into the upper space of the slit 21. Furthermore, the fixing piece 43 can be fixed in a state where the engaging portion 43a is fitted to the slit 21 by attaching the fastening bolt 43c, which is a fastener, to the screw hole 19 through the through hole 43b. Thereby, the 1st long plate member 41 and the 2nd long plate member 42 can be firmly fastened via the coupling | bond part 20. As shown in FIG.

  In addition, the neutron absorption member 12 accommodated in the accommodating part 13 is a board | plate material made from the aluminum alloy containing a boron compound, as mentioned above, and is for preventing the criticality of a spent nuclear fuel. And as shown in FIG. 7, the notch part 12a which avoids interference is formed in the part by which the fixed piece 43 is arrange | positioned by the neutron absorption member 12. As shown in FIG.

  As shown in FIG. 8, the basket 10 includes a large block body 14 </ b> A in which a stepped portion in which the square pipe 40 is fitted is formed on the inner surface of the bundle 11 made of the carbon steel square pipe 40. Small block bodies 14 </ b> B whose inner surfaces are formed in a plane along the tangential direction are alternately arranged. A pair of mounting recesses 14a are formed in the large block body 14A at a predetermined interval in the circumferential direction. Then, both end portions of the band member 44 are fixed to mounting recesses 14a of the large block body 14A adjacent to each other with the small block body 14B interposed therebetween via mounting bolts 14b as fasteners. As a result, the bundle 11 made of carbon steel square pipes 40 having a relatively low thermal expansion coefficient is surrounded by the aluminum alloy block bodies 14A and 14B having a high thermal expansion coefficient, and the outer peripheral portion is made of a steel band member 44. The bundle 11 can be held without restraining circumferential stress due to thermal expansion. Thereby, the deformation of the square pipe 40 due to thermal expansion does not occur, and the breakage and strength of the coupling portion 20 are not impaired.

  According to the above embodiment, by assembling the square pipe 40 with the first long plate member 41 and the second long plate portion 42 through the engaging portion 20, welding is not required and the production period can be shortened. Manufacturing costs can be reduced. Further, by projecting the second long plate member 42 from both edge portions of the first long plate member 41 at the four corners of the square pipe 40, the edge portions of the pair of second long plate members 42 have a simple structure. The accommodating part 13 of the neutron absorbing member 12 can be formed therebetween.

  Further, in the coupling portion 20, the claw portion 15 formed on the first long plate member 41 is engaged with the slit 21 formed on the second long plate member 42, and the claw portion 15 is slit by the fixing piece 43. The pair of first long plate members 41 and the pair of second long plate members 42 are fastened together to assemble the rectangular pipe 40 having a rectangular cross section. It can be assembled firmly and the production cost can be reduced.

  Further, the plurality of square pipes 40 constituting the bundle 11 are closed by alternately arranging the square pipes 40 in the upright posture and the square pipes 40 in the fall posture rotated about the axis. Thus, the neutron absorbing member 13 can be stably held.

  Further, a plurality of block bodies 14A and 14B are arranged on the outer peripheral portion of the bundle body 11, and the adjacent large block bodies 14A among these block bodies 14A and 14B are connected by a band member 44 to restrain the square pipe 40. Therefore, the bundle body 11 can be securely held without suppressing the circumferential stress of the bundle body 11 due to thermal expansion, and the square pipe 40 is not adversely affected.

By forming the constituent members of the square pipe 40 from carbon steel, the strength of the bundle 11 can be ensured, and the block bodies 14A and 14B are made of aluminum alloy, thereby increasing the thermal conductivity of the basket 10. be able to. Furthermore, a bundle 11 of coefficient of thermal expansion is relatively low carbon steel square pipe 40, the thermal expansion coefficient is relatively large aluminum alloy of the block body 14A, surrounds at 14B, to restrain the band member 44 Thus, the bundle 11 can be reliably held by absorbing the thermal expansion in the radial direction due to the decay heat.

  Here, although the first long plate member 41 and the second long plate member 42 which are constituent members of the square pipe 40 are made of carbon steel, they may be made of carbon steel alloy steel. Moreover, although the neutron absorbing member 21 is made of an aluminum alloy containing boron or a boron compound, it may be made of an aluminum alloy containing boron or a boron compound, or an aluminum alloy containing cadmium or samarium.

DESCRIPTION OF SYMBOLS 10 Basket 11 Bundle body 12 Neutron absorption member 13 Accommodating part 14A (Large) Block body 14B (Small) Block body 15 Claw part 16 Gutter part 18 Notch part 20 Coupling part 21 Slit 22 Locking surface 40 Square pipe 41 First Long plate member 42 Second long plate member 43 Fixed piece 43a Engaging portion 44 Band member

Claims (5)

A cask basket in which a bundle of square pipes is formed by arranging the side surfaces of a plurality of square pipes facing each other,
In the square pipe, a pair of first long plate members opposed to each other and a pair of second long plate members opposed to each other are assembled into a rectangular cross section via a coupling portion,
At the four corners of the square pipe, the two long edges of the second long plate member protrude from the two long edges of the first long plate member to be flush with each other. A cask basket characterized in that an accommodating portion for accommodating a neutron absorbing member is formed. The joint is
A plurality of claw portions that are projected at predetermined intervals on both long edge portions of the first long plate member, and a collar portion is formed on one end portion in the length direction;
A plurality of slits formed on both long edge portions of the second long plate member and engaged with the claw portions, respectively;
A fixing piece that is engaged with the other of the slits in the length direction, and that presses the collar portion of the claw portion against one end portion in the length direction of the slit to prevent the claw portion from coming off from the slit. The cask basket according to claim 1, wherein the basket is a basket. The bundled square pipes are arranged with adjacent square pipes rotated 90 degrees around the axis,
The cask basket according to claim 2, wherein the accommodating portion is closed by a first long plate member of an adjacent square pipe. A plurality of block bodies having a substantially fan-shaped cross section arranged at predetermined intervals on the outer periphery of the bundle body,
A cask basket, comprising: a plurality of band members fastened between the two block bodies arranged in the circumferential direction to restrain the bundle. The component of the square pipe is made of carbon steel or carbon steel alloy steel,
The cask basket according to claim 4, wherein the block body is made of an aluminum alloy.

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