JP2005214870A - Canister for housing fuel assembly to be recycled - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize a canister for housing fuel assemblies to be recycled which has a double structure that a body of a trunk is fixed onto a sleeve formed inside it. <P>SOLUTION: This canister 200 for housing the fuel assemblies to be recycled consists of the body 201t of the trunk which houses them inside it, a sleeve 220 which is composed of a material different from that for the body 201t of the trunk and is located in it and whose wall thickness is smaller than that of the trunk, a flange 210 which is made of the same material as that for the sleeve 220 and whose section joined to an opening 201to of the main body 201t of the trunk is jointed to the body 201t of the trunk in a first juncture W<SB>1</SB>and is also jointed to the sleeve 220 in a second juncture W<SB>2</SB>by forming a flange side step 210d so as to fit to the contour of a side step 201td of the body 201t of the trunk and a lid mounted on the flange 210. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a recycled fuel assembly storage container for storing a recycled fuel assembly, and more particularly to a double-structured recycled fuel assembly storage container having a sleeve inside a trunk body.

  A nuclear fuel assembly at the end of the nuclear fuel cycle that cannot be used after combustion is called a recycled fuel assembly. Since the recycled fuel assembly contains a highly radioactive substance such as FP, it needs to be cooled thermally, and is thus cooled in a cooling pit of a nuclear power plant for a predetermined period (5 to 15 years). Thereafter, it is stored in a recycle fuel assembly storage container having a shielding function, generally called a cask, and is transported and stored in a reprocessing facility by a vehicle or ship. As such a recycled fuel assembly storage container, for example, Patent Document 1 discloses a container having a container with a double vessel.

Special table 2003-524786 gazette

  By the way, the container disclosed by patent document 1 pays attention to prevention of the penetration | invasion of the water to an inside. For this reason, it is the structure which equips the inside of the trunk | drum main body called a body with the 2nd trunk | drum called a flask, Comprising: It becomes the structure which supports a flask without fixing to a body via a sealing means. Therefore, although effective against water intrusion, it has been difficult to maintain the seal for a long time.

  Further, among the radioactive materials, the recycled fuel assembly generates a lot of decay heat, so that the flask thermally expands. Thereby, the deformation of the flask, the deformation of the sealing means, etc. may occur. In order to solve such a problem, a method of fixing the flask to the body by joining can be considered. However, Patent Document 1 does not mention such a fixing structure, and does not mention any problems that occur when such a fixing structure is adopted.

  Accordingly, the present invention has been made in view of the above, and an object thereof is to provide a recycled fuel assembly storage container capable of realizing a double structure in which a trunk body and a sleeve provided therein are fixed. .

  In providing a double-structured recycle fuel assembly storage container in which a trunk body and a sleeve provided therein are fixed, decay heat generated by the recycle fuel assembly stored inside becomes a problem. Due to this decay heat, the recycled fuel assembly storage container expands. In particular, when the body and the sleeve are made of different materials, thermal stress is generated in the fixed portion due to the difference in thermal expansion coefficient between the two. Since the durability of the fixing portion may be reduced due to the thermal stress, a structure that relaxes the thermal stress is required when the body and the sleeve are made of different materials. As a result of earnest research focusing on this point, the inventors of the present application have solved the above problems by fixing the trunk body and the sleeve indirectly and firmly, for example, by welding, and making the sleeve inflatable. The present inventors have found that this can be done and have completed the present invention.

  In order to solve the above problems and achieve the object of the present invention, a recycled fuel assembly storage container according to the present invention is provided with a bottom at one end of a cylindrical body and an opening at the other end. A barrel body in which a first step portion is formed inside the opening, and a recycled fuel assembly that is made of a material different from the barrel body and is disposed in the barrel body A sleeve having a thickness smaller than the thickness of the trunk portion, and a cylindrical member, the portion to be combined with the opening of the trunk main body according to the shape of the first step portion. A second step portion is formed, and is fixed to the trunk main body at a portion in contact with the end portion of the opening, and further, the end portion of the sleeve is fixed to the inner peripheral side and the end portion on the bottom side. The furan made of the same material as the sleeve When, characterized in that it is configured to include a cover attached to the opening side of the flange.

  In this recycled fuel assembly storage container, when a sleeve made of a different material is fixed inside the trunk body, the sleeve is indirectly fixed to the trunk body via a flange made of the same material as the sleeve. Further, the step provided in the fixing portion between the flange and the trunk body can receive the thermal stress generated due to the difference in thermal expansion between the two. Thereby, the thermal stress of the fixed part generated due to the thermal expansion difference between the flange and the trunk body can be relaxed, and the durability of this part can be maintained. As a result, it is possible to realize a double structure in which the trunk body and the sleeve provided therein are fixed. The opening of the flange to which the lid is attached is on the side opposite to the side on which the sleeve is fixed.

  The recycled fuel assembly storage container according to the present invention is a stress relief structure including a curved surface between a fixing portion between the flange and the sleeve and a fixing portion between the flange and the trunk body. A portion is provided.

  Since this recycled fuel assembly storage container has the same configuration as the recycled fuel assembly storage container, the same operation and effect as the storage container are exhibited. Further, the recycled fuel assembly storage container includes a stress relaxation portion including a curved surface between a portion where the flange and the sleeve are fixed and a portion where the flange and the trunk body are fixed. . As a result, the bending stress of the fixing portion between the flange and the sleeve, which is generated due to the decay heat from the recycled fuel assembly, can be relieved, so that the durability of this portion can be maintained. As a result, it is possible to realize a double structure in which the trunk body and the sleeve provided therein are fixed, and it is possible to further improve the durability.

  The radius of the curved surface constituting the stress relaxation part is not less than 1/6 and not more than 3/4 of the radial thickness of the flange as defined in the recycled fuel assembly storage container according to the present invention. Is preferred. If it is this range, the bending stress of the fixing part of a flange and a sleeve can fully be relieved.

  The recycled fuel assembly storage container according to the present invention is characterized in that in the recycled fuel assembly storage container, a predetermined clearance is provided between the sleeve and the bottom of the cavity.

  Since this recycled fuel assembly storage container has the same configuration as the recycled fuel assembly storage container, the same operation and effect as the storage container are exhibited. Further, the recycled fuel assembly storage container has a predetermined clearance between the sleeve and the bottom of the cavity. As a result, thermal expansion in the axial direction of the sleeve can be absorbed, so that deformation of the sleeve due to the thermal expansion is suppressed, and a double structure in which the trunk body and the sleeve provided therein are fixed is realized. it can.

  The recycled fuel assembly storage container according to the present invention is characterized in that, in the recycled fuel assembly storage container, the flange and the lid are made of the same material.

  Since this recycled fuel assembly storage container has the same configuration as the recycled fuel assembly storage container, the same operation and effect as the storage container are exhibited. Further, in this recycled fuel assembly storage container, since the flange and the lid are made of the same material, the thermal expansion between the flange and the lid can be made substantially equal. Thereby, the thermal stress which generate | occur | produces in the fixing means of a flange and a lid | cover is relieve | moderated, and the sealing structure excellent in reliability can be implement | achieved.

  The recycled fuel assembly storage container according to the present invention is characterized in that, in the recycled fuel assembly storage container, the sleeve and the flange are made of stainless steel.

  A recycled fuel assembly is accommodated in the sleeve. Further, since the recycled fuel assembly is carried into the recycled fuel assembly storage container in water, the sleeve is required to have corrosion resistance. Corrosion resistance can be ensured by using stainless steel for the sleeve as in this recycled fuel assembly storage container. Further, a lid is attached to the flange by a fastening means such as a bolt, but if stainless steel having excellent corrosion resistance is used for the flange, the corrosion treatment of the bolt hole becomes unnecessary. Thereby, the manufacturing process of a recycle fuel assembly storage container can be simplified.

  A recycled fuel assembly storage container according to the present invention is a container in which a bottom portion is provided at one end of a cylindrical body portion and an opening portion is provided at the other end. The trunk body in which the first step portion is formed, the trunk body is made of a material different from that of the trunk body, and is disposed in the trunk body to store the recycled fuel assembly, and further than the thickness of the trunk portion. A sleeve having a small wall thickness and a cylindrical member, which is fixed to the body main body at a portion in contact with the end of the opening, and is provided on the inner peripheral side and the end on the bottom side A flange made of the same material as the sleeve to which an end of the sleeve is fixed; a lid attached to the opening side of the flange; and a portion to which the flange and the sleeve are fixed; And the trunk body Between the portion to be characterized in that the stress absorbing portions configured to include a curved surface is provided.

  The recycle fuel assembly storage container includes a stress relaxation portion including a curved surface between a portion where the flange and the sleeve are fixed and a portion where the flange and the trunk body are fixed. As a result, the bending stress of the fixing portion between the flange and the sleeve, which is generated due to the decay heat from the recycled fuel assembly, can be relieved, so that the durability of this portion can be maintained. As a result, it is possible to realize a double structure in which the trunk body and the sleeve provided therein are fixed.

  The radius of the curved surface constituting the stress relaxation part is not less than 1/6 and not more than 3/4 of the radial thickness of the flange as defined in the recycled fuel assembly storage container according to the present invention. Is preferred. If it is this range, the bending stress of the fixing part of a flange and a sleeve can fully be relieved.

  The recycled fuel assembly storage container according to the present invention has an effect of realizing a double structure in which a trunk body and a sleeve provided therein are fixed.

  Hereinafter, the present invention will be described in detail with reference to the drawings. The present invention is not limited to the best mode for carrying out the invention. In addition, constituent elements in the following embodiments include those that can be easily assumed by those skilled in the art or that are substantially the same. The recycled fuel assembly storage container according to the present invention described below can be used for any purpose of transporting, storing, transporting or storing the recycled fuel assembly. The recycled fuel assembly storage container according to the present invention can be applied regardless of whether it is a BWR (Boiling Water Reactor) or a PWR (Pressurized Water Reactor). In particular, the present invention can be preferably applied to storing a PWR recycled fuel assembly having a high burnup and a large calorific value.

In the following embodiments, joining, welding, and other joining means are used for fixing the flange and the trunk body and fixing the sleeve and the flange, but applicable fixing means are not limited thereto. Further, in the following embodiments, the fixing portion between the flange and the trunk body and the fixing portion between the sleeve and the flange are referred to as a first joint portion W ₁ and a second joint portion W ₂ , respectively.

  Further, in the following embodiments, a case where the sleeve and the trunk body are made of different materials and the thermal expansion coefficient of the sleeve is larger than the thermal expansion coefficient of the trunk body will be described. It is not limited to such a case. As an example of such a combination, the case where the sleeve is made of stainless steel and the body is made of carbon steel will be described as an example. However, applicable materials are not limited to this combination. That is, it is only necessary that the thermal expansion coefficients of the sleeve material and the trunk body material are different. In particular, the present invention can be suitably applied when the thermal expansion coefficient of the sleeve material is larger than the thermal expansion coefficient of the body material.

  The recycled fuel assembly storage container according to the first embodiment is characterized in the following points. That is, when a sleeve made of a different material is fixed inside the trunk body, the sleeve is indirectly fixed to the trunk body via a flange made of the same material as the sleeve. A step portion is formed in the fixing portion between the flange and the trunk body, and the thermal stress generated in the fixing portion is relieved by receiving a difference in thermal expansion between the flange and the trunk body by the step portion. Next, the overall configuration of the recycled fuel assembly storage container according to the first embodiment will be described.

FIG. 1 is an overall view showing a recycled fuel assembly storage container according to the first embodiment. 2 is a cross-sectional view parallel to the axial direction of the recycled fuel assembly storage container shown in FIG. 3 is a view taken in the direction of arrows XX in FIG. As shown in FIG. 1, the recycled fuel assembly storage container 200 includes a lid 200T and a trunk 200B. Then, after the recycled fuel assembly is accommodated in the body 200B, it is sealed with the lid 200T. As shown in FIGS. 1 and 2, the lid 200T further includes a primary lid 200T ₁ and a secondary lid 200T ₂ .

The primary lid 200T ₁ and the secondary lid 200T ₂ are made of stainless steel having a thickness of about several tens of cm to 30 cm in order to shield γ rays emitted from the recycled fuel assembly. The secondary lid 200T ₂ is filled with a neutron absorbing material 209 having a function of absorbing neutrons in order to shield neutrons emitted from the recycled fuel assembly. As a material having such a function, a polymer material containing a large amount of hydrogen (H) having excellent neutron absorbability (for example, resin, polyurethane), silicon, or other neutron absorbing materials can be used. With this neutron absorbing material, neutrons emitted from the recycled fuel assembly are shielded, and neutrons leaking to the outside of the recycled fuel assembly storage container 200 are reduced below the regulation value. In addition, a high-pressure inert gas is filled between the primary lid 200T ₁ and the secondary lid 200T ₂ , thereby further ensuring the sealing.

  The cylinder 200B of the recycled fuel assembly storage container 200 is attached to a cylindrical trunk body 201t, a heat transfer fin 207 attached to the outer periphery of the cylinder body 201t, and the other long side end of the heat transfer fin 207. It is comprised with the outer cylinder 205 (refer FIG. 1, FIG. 2). The trunk body 201t is made of carbon steel having a sufficient thickness in order to exhibit the function of shielding γ rays. In addition, when manufacturing the trunk | drum main body 201t with carbon steel, in order to exhibit sufficient gamma ray shielding function, the thickness of the trunk | drum main body 201t is 20-30 cm. Here, the thickness of the trunk body 201 refers to the thickness of the trunk portion, that is, the thickness of the cylindrical portion (trunk portion).

  A sleeve 220 made of stainless steel is disposed inside the trunk body 201t. The thickness of the sleeve is smaller than the thickness of the trunk body 201t, and is about 1/10 of the thickness of the trunk body. This facilitates the homogenization of the material structure, so that a material with few defects can be easily obtained. The sleeve 220 includes a bottom portion 220b, and a recycled fuel assembly housed in the basket 300 is disposed therein. The sleeve 220 is manufactured by welding a stainless steel bottom plate to an end portion of a stainless steel tube. However, the sleeve 220 may be manufactured by integrally forming the bottom portion 220b by backward extrusion molding or extrusion molding. . Since the sleeve 220 is in contact with water, corrosion resistance is required. However, by manufacturing the sleeve from stainless steel, such a requirement can be sufficiently satisfied.

  As described above, the recycled fuel assembly storage container 200 according to the first embodiment includes a double barrel made of different materials in which the stainless steel sleeve 220 is disposed in the carbon steel barrel main body 201t. Stainless steel has a thermal expansion coefficient about 10 times greater than that of carbon steel. Since the recycled fuel assembly storage container 200 stores therein the recycled fuel assembly that generates decay heat, the sleeve 220 and the trunk body 201t are thermally expanded. For this reason, if the stainless steel sleeve 220 is simply disposed within the carbon steel body body 201t, a large stress acts on the connection between the sleeve 220 and the body body 201t due to the difference in thermal expansion coefficient. There is a risk of damage.

Therefore, in the recycled fuel assembly storage container 200 according to the first embodiment, the sleeve 220 is indirectly attached to the trunk body 201t through the flange 210 made of the same material as the sleeve 220. More specifically, the lid 200T side of the trunk body 201t, a flange 210 of the sleeve 220 and the tubular manufactured of stainless steel of the same material (in Embodiment 1 cylinder) is joined by the first joining portion W _1. Then, the flange 210, the sleeve 220 are joined at a second junction W _2. With such a configuration, the sleeve 220 is attached to the trunk main body 201t via the flange 210, and the stress generated due to the difference in thermal expansion coefficient is relieved. The details of the attachment portion between the flange 210 and the trunk body 201t and the attachment portion between the flange 210 and the sleeve 220 will be described later.

As shown in FIG. 2, the primary lid 200T ₁ and the secondary lid 200T ₂ are attached to the flange 210. Since the flange 210 is made of stainless steel and has a thermal expansion coefficient about twice that of carbon steel, the primary lid 200T ₁ and the secondary lid 200T ₂ are also made of stainless steel, which is the same material as the flange 210, and the primary lid 200T ₁ and Due to the difference in thermal expansion coefficient generated between the secondary lid 200T ₂ and the flange 210, the stress generated in the fixing portion between the flange 210 and the primary lid 200T ₁ or the secondary lid 200T ₂ is relieved. .

In Example 1, since the flange 210 is made of stainless steel, the following advantages can be obtained. A primary lid 200T ₁ and a secondary lid 200T ₂ are attached to the flange 210 by bolts or other fastening means. Since the recycled fuel assembly storage container carries the recycled fuel in water, the flange 210 comes into contact with water, and the bolt hole for screwing the bolt is also submerged. For this reason, although the said bolt hole needs anticorrosion measures, since the flange 210 is manufactured with stainless steel excellent in corrosion resistance, such anticorrosion measures become unnecessary. Thereby, the manufacturing process of the flange 210 can be simplified.

A bottom plate 201b is attached by welding to the end opposite to the side on which the lid 200T is attached to the trunk main body 201t (joining portion W ₃ ), and constitutes the bottom of the trunk main body 201t. The bottom plate 201b is made of carbon steel or stainless steel with sufficient heat in order to have a γ-ray shielding function and a neutron shielding function, and is filled with the above-described neutron absorbing material 209. By inserting a metal billet into a container having an internal shape that matches the outer shape of the barrel main body 201t, and hot expanding the metal billet with a perforated punch having an outer shape that matches the inner shape of the barrel main body 201t. The trunk body 201t and the bottom plate 201b may be integrally formed. Furthermore, you may manufacture the trunk | drum main body 201t by casting.

  Inside the trunk body 201t is a cavity 201c in which the basket 300 for storing the recycled fuel assembly is stored (FIG. 2). As shown in FIG. 3, in the first embodiment, the shape in the cross section perpendicular to the axial direction (direction indicated by Z in the figure) of the cavity 201c is circular, but according to the specifications of the recycled fuel assembly storage container 200. Also, a cavity having a cross-sectional shape such as an octagon, a substantially cross shape, or a step shape can be used. In this case, the inner shape of the sleeve 220 is also a shape that matches the inner shape of the cavity 201c. In the first embodiment, the shape of the cavity 201c in the cross section is circular. Therefore, when the basket 300 having a polygonal outer shape is stored, the first basket support 302a and the second basket support 302b are attached to the basket 300. The basket 300 is disposed in the cavity 201c with a space between the cavity 201c and the cavity 201c.

After the recycled fuel assembly is housed in the cavity 201c, the primary lid 200T ₁ and the secondary lid 200T ₂ are double-sealed to prevent radioactive material from leaking from the sleeve 220 in the cavity 201c. In order to ensure sealing performance, a metal gasket is provided between the flange 210 to which the sleeve 220 is attached and the primary lid 200T ₁ and the secondary lid 200T ₂ .

  A plurality of heat transfer fins 207 made of a plate-like member are radially attached to the outer periphery of the trunk body 201t. Further, an outer cylinder 205 made of carbon steel having a thickness of several centimeters is attached to the outside of the heat transfer fin 207. In the first embodiment, the heat transfer fins 207 are made of carbon steel, which is the same material as the trunk main body 201t and the outer cylinder 205, in consideration of ease of manufacture. Thereby, since the heat transfer fin 207 can be attached by welding the same kind of material, manufacture becomes easy. In consideration of heat transfer performance, the heat transfer fins 207 may be made of a heat conductive material such as an aluminum plate or a copper plate. In this case, since different materials are joined, it is necessary to devise the joining.

  The recycled fuel assembly housed in the cavity 201c generates decay heat. The decay heat is transmitted to the outer cylinder 205 through the heat transfer fins 207 after being transmitted through the basket 300 and the trunk body 201t, and is released into the atmosphere from the surface of the outer cylinder 205. As shown in FIG. 3, in the recycled fuel assembly storage container 200 according to the first embodiment, the long-side end portions of the plurality of flat plates 205p are connected to the end portions of the heat transfer fins 207 (the end portions on the joint side with the body main body 201t). Are joined to the opposite side) to constitute the outer cylinder 205.

  As described above, since the plurality of flat plates 205p are joined to the heat transfer fins 207, the flat plate 205p can be joined to the heat transfer fins 207 after the heat transfer fins 207 are joined to the outer periphery of the trunk body 201t. be able to. A space surrounded by the trunk body 201t, the flat plate 205p constituting the outer cylinder 205, and the two heat transfer fins 207 is filled or arranged with a neutron absorbing material 209. Thereby, the neutron emitted from the recycle fuel assembly stored in the basket 300 is shielded.

  FIG. 4A is an enlarged view of a portion indicated by B in FIG. The recycled fuel assembly storage container 200 is provided with a predetermined clearance tb between the bottom 201bt and the bottom end 220bt of the sleeve 220 in order to absorb the extension of the sleeve 220 in the axis Z direction. Thereby, even when the sleeve 220 is thermally expanded in the axis Z direction, the sleeve 220 can be prevented from coming into contact with the bottom portion 201bt. FIG. 4-2 is an enlarged view showing a clearance between the sleeve and the trunk body. A predetermined clearance tc is provided between the outer peripheral surface of the sleeve 220 and the inner peripheral surface of the trunk main body 201t.

  The clearance tc becomes substantially zero when the sleeve 220 is thermally expanded in the radial direction, and the sleeve 220 and the trunk body 201t come into contact with each other. Thereby, the heat transfer between the sleeve 220 and the trunk main body 201t is improved. At this time, the sleeve 220 is thermally expanded in the direction of the axis Z. At this time, in order to reduce friction between the sleeve 220 and the body main body 201t, carbon is interposed between the outer peripheral surface of the sleeve 220 and the inner peripheral surface of the body main body 201t. It is preferable to interpose a lubricant such as powder or molybdenum disulfide. In particular, a heat good conductor such as carbon powder is more preferable.

  The recycled fuel assembly storage container 200 according to the first embodiment is used for transporting and storing after storing the recycled fuel assembly. When transporting the recycled fuel assembly storage container 200, shock absorbers are attached to both ends in the axis Z direction of the recycled fuel assembly storage container 200, so that an accident such as a fall of the recycled fuel assembly storage container 200 occurs. Even in this case, sufficient sealing performance can be secured.

  FIG. 5-1 is a plan view illustrating another example of a flat plate constituting the outer cylinder of the recycled fuel assembly storage container according to the first embodiment. FIG. 5-2 is a view as seen from the direction of arrow C in FIG. 5-1. The flat plate 205p ′ has a plurality of protrusions 230 extending in the longitudinal direction of the flat plate 205p ′ on the heat dissipation surface, that is, the surface opposite to the bonding surface of the heat transfer fins 207. And as shown to FIGS. 5-2, the surface in which the protrusion 230 is formed contacts air | atmosphere. Thereby, since the heat radiation area of the flat plate 205p ′ can be increased, it is particularly suitable for storing a recycled fuel assembly for PWR that has a high burnup and generates a large amount of heat.

  FIG. 6 is a plan view illustrating another configuration of the outer cylinder of the recycled fuel assembly storage container according to the first embodiment. The outer cylinder 205a has, for example, a cylindrical shape that is integrally manufactured by bending a carbon steel plate and welding the ends. A heat transfer fin 207 is arranged between the outer cylinder 205a and the trunk body 201t. In this configuration, since the heat transfer fins 207 must be joined between the outer surface of the trunk body 201t and the inner surface of the outer cylinder 205a, it takes time to manufacture. However, since the outer cylinder 205a is integrally formed, there is an advantage that the strength is high and the sealing performance of the neutron absorber is also high.

  The recycled fuel assembly storage container having the outer cylinder shown in FIG. 6 can be manufactured, for example, as follows. First, the heat transfer fins 207 are fixed to the outside of the trunk body 201t by welding, joining or other means. Thereafter, the outer cylinder 205a is arranged outside the heat transfer fin 207, and then the outer side 205a and the long side end of the heat transfer fin 207 on the outer cylinder 205a side are fixed by welding, joining, or other means.

  Moreover, you may manufacture the recycle fuel assembly storage container which has an outer cylinder shown in FIG. 6 as follows. First, after the cylindrical outer cylinder 205a is disposed outside the trunk body 201t, the heat transfer fins 207 are disposed between the outer surface of the trunk body 201t and the inner surface of the outer cylinder 205a. Then, both long side end portions of the heat transfer fin 207 may be fixed by welding, joining or other means between the inner surface of the outer cylinder 205a and the outer surface of the trunk body 201t. The heat transfer fin 207 is a plate having a rectangular shape when viewed from the side, and the end on the long side is referred to as the long side end.

  Next, the basket 300 stored in the recycled fuel assembly storage container will be described. FIG. 7A is an explanatory diagram of an example of a basket that stores a recycled fuel assembly. This basket 300 is configured by combining plate-like members 310 having through holes 311 partitioned by ribs 313 and laminating a plurality of stages. A plurality of cutout portions 312 are formed at the long side end portion 310lt of the plate member 310, and the cutout portions 312 are combined with each other by making the plate members 310 orthogonal to each other. When assembling the basket 300, first, the plate-like members 310 constituting the first stage are arranged in parallel. Then, the plate-like member 310 constituting the second stage is made orthogonal to the plate-like member 310 constituting the first stage, and the notch portions 312 of the plate-like member 310 of the first stage and the second stage are combined. . This is sequentially repeated, and the plate-like member 310 is laminated to a required height, whereby the basket 300 is completed.

  FIG. 7-2 is a cross-sectional view showing an example of a basket for storing the recycled fuel assembly. The basket 300 is configured by combining a plurality of plate-like members 310 so as to be orthogonal to each other. Thereby, the basket 300 includes a lattice-shaped space surrounded by the plurality of plate-like members 310. This space is called a cell, and is numbered in FIG. 6-2. The basket 300 shown in FIG. 6B has a total of 24 cells, and the recycled fuel assemblies are stored in these cells.

  The number of cells is not limited to 24, and can be changed as appropriate according to the specifications of the recycled fuel assembly storage container 200. Further, the basket 300 stored in the recycled fuel assembly storage container 200 is not limited to a combination of a plurality of plate-like members 310. For example, the configuration of the recycle fuel assembly storage container 200, such as a combination of square pipes with hollow walls arranged in a grid, or a hollow spacer arranged between square pipes arranged in a grid, etc. Various baskets can be used accordingly.

  As shown in FIG. 3, the cavity 201 c included in the recycled fuel assembly storage container according to the first embodiment has a circular cross-sectional shape perpendicular to the axis Z direction. For this reason, in order to match the outer shape of the basket 300 with the inner shape of the cavity 201 c, the longitudinal length of the plate-like member 310 varies depending on the location of the basket 300. Moreover, in order to arrange | position the basket 300 reliably in the cavity 201c, the 1st basket support body 320a and the 2nd basket support body 320b are attached to the required location in the outer periphery of the basket 300. FIG. Then, the basket 300 is disposed in the cavity 201c. Next, the flange mounting portion of the recycled fuel assembly storage container according to the first embodiment will be described.

FIG. 8 is an enlarged view of a flange mounting portion of the recycled fuel assembly storage container according to the first embodiment. FIG. 9 is an enlarged view of the recycled fuel assembly storage container according to the first embodiment before joining the flange mounting portion. FIG. 10A is a cross-sectional view parallel to the axis of the flange. 10-2 is a plan view when the flange is viewed from the direction of arrow D in FIG. 10-1. The flange 210 and the cylinder body 201t, (using in Example 1 the weld) are joined and the first joint portion W _1. As shown in FIGS. 8 and 9, the first joint W _{1 of} the trunk body 201t, that is, the flange-side opening end of the trunk body 201t has a first step portion (hereinafter referred to as a trunk body side step portion) formed in a step shape. ) 201td is provided. The first joint portion W ₁ of the flange 210, adapted to the cylinder body side step 201Td, i.e., the second step portion of the shape to be combined with the barrel main body side step 201Td (hereinafter the flange side step) 210d is provided ing.

When joining the flange 210 and the cylinder body 201t in the first joint portion W _1, and the flange side step 210d and trunk body side step 201td are combined, a meshing configuration. With such a configuration, when the stainless steel flange 210 thermally expands radially outward (direction indicated by RR in FIG. 8) due to the decay heat of the recycled fuel assembly, the flange side radial contact surface 210dp, The main body side radial contact surface 201tdp contacts. Thereby, the thermal expansion of the flange 210 is restrained by the trunk body side step portion 201td. As a result, the stress of the first joint W ₁ generated due to the thermal expansion of the flange 210 can be extremely reduced, so that the soundness of the first joint W ₁ can be sufficiently ensured. In particular, this structure is suitable for storing a PWR recycled fuel assembly having a high burnup and a large calorific value.

Combined with the flange side step 210d and trunk body side step 201td is stepped portion width h of the portion meshing when the flange 210 is thermally expanded, damage to the first joining portion W ₁ and the second joining portion W ₂ is The size does not occur. More specifically, the magnitude of the joint depth ΔR ₁ and the bending stress (stress indicated by arrow B in FIG. 9) acting on the second joint W ₂ between the flange 210 and the sleeve 220 are considered. This is because if the step width h is increased when the joining depth ΔR ₁ is small, an excessive stress acts on the base portion 201 tdb of the trunk body side step 201 td. Also, the bending stress acting on the second joint W ₂ increases as the step width h increases. The step width h is a compression acting on the flange side radial contact surface 210dp and the cylinder body radial contact surface 201tdp in consideration of the above matters and the material properties of the flange 210 and the body main body 201t. The stress is determined to have a magnitude that does not exceed the elastic limit of the stainless steel constituting the flange 210 and the carbon steel constituting the trunk body 201t.

Further, the step width hf of the flange side stepped portion 210d may be made smaller than the trunk body side stepped portion width hp by taking into account thermal expansion in the direction of the flange axis Zf (see FIG. 9). In this way, the flange 210 is thermally expanded to the flange axis Zf direction, can be alleviated force to open the flange 210 and the first joint portion W ₁ is a junction of the trunk body 201t. Here, the step width is the size in the axis Z direction of the recycled fuel assembly storage container 200 at the flange side step 210d or the trunk body side step 201td, and is the size in the flange axis Zf direction.

Here, the attachment structure of the flange 210, the primary lid 200T ₁ and the secondary lid 200T ₂ will be described. Between the flange 210 and the primary lid 200T _1, and between the flange 210 and the secondary lid 200T _2, metal gaskets 231 and 232 are respectively provided. Both the metal gaskets 231 and 232 are attached to the inside of the grooves 241 and 242 provided in the primary lid 200T ₁ and the secondary lid 200T ₂ , respectively. When the primary lid 200T ₁ and the secondary lid 200T ₂ are attached by the metal gaskets 231 and 232, the cavity 201c included in the recycled fuel assembly storage container 200 is kept sealed.

Depending on the material with which the metal gaskets 231 and 232 are in contact, it is necessary to consider corrosion of the contact surface. For this reason, depending on the material of the contact surface, it is necessary to coat the surface with chromium or the like. However, in Example 1, the flange 210 with which the metal gaskets 231 and 232 are in contact with, the primary lid 200T ₁ and the secondary lid 200T ₂ are all made of stainless steel, so that the coating is not necessary. Thus, flange 210, to simplify the primary lid 200T ₁ and the secondary lid 200T ₂ of the manufacturing process, can be easily produced recycled fuel assembly storage container 200.

The flange 210 and the sleeve 220 are joined by the second joining portion W _2. In Embodiment 1, EBW (Electron Beam Welding) is used for this joining, but other joining methods may be used. In the first embodiment, the flange between the flange 210 and the sleeve 220 (second joint W ₂ ) and the joint between the flange 210 and the trunk body 201 t (first joint W ₁ ) has a flange. A stress relieving portion is provided for relieving bending stress generated at the joint between 210 and the sleeve 220. Due to the thermal expansion of the flange 210, the flange 210 expands in the radial direction (the direction indicated by the arrow RR in FIG. 7), and this causes a bending stress (at the joint between the flange 210 and the sleeve 220) to open this portion. The direction indicated by the arrow B in FIG. 8 acts. Therefore, if this bending stress is not relaxed, the joint W ₂ between the flange 210 and the sleeve 220 may be broken.

  For this reason, in Example 1, the stress relaxation part 250 is provided between the junction part of the flange 210 and the trunk | drum main body 201t from the junction part of the flange 210 and the sleeve 220. FIG. More specifically, the stress relaxation part 250 having a curved surface shape with a radius r centered on the point C between the flange 210 and the sleeve 220 and the flange side step part 210d and the trunk body side step part 201td. Is provided. The stress relaxation portion 250 relieves bending stress generated at the joint between the flange 210 and the sleeve 220. With such a configuration, the soundness of the joint between the flange 210 and the sleeve 220 can be ensured.

  The radius r of the stress relaxation portion is preferably 1/6 or more and 3/4 or less, and more preferably 1/4 or more and 1/2 or less of the radial thickness ΔR (= Ro−Ri) of the flange. Further, the point C, which is the center of the curved surface of the stress relieving portion, is preferably provided at a position of a predetermined size hc from the sleeve joint end surface 210st of the flange 210 toward the primary lid attachment end surface 210bt. In this case, the mechanical properties of the material change in the vicinity of the joint between the flange 210 and the trunk body 201t, but the influence is avoided.

  As described above, in the recycled fuel assembly storage container according to the first embodiment, when fixing a sleeve made of a different material to the inside of the trunk body, the sleeve is indirectly attached to the trunk body via the flange made of the same material as the sleeve. Fix it. And the thermal stress which arises due to the thermal expansion difference of both is received by the step part provided in the fixing | fixed part of a flange and a trunk | drum main body. Thereby, the thermal stress of the fixed part generated due to the thermal expansion difference between the flange and the trunk body can be relaxed, and the durability of this part can be maintained. As a result, it is possible to realize a double structure in which the trunk body and the sleeve provided therein are fixed.

  In addition, a gap between the cylinder body and the sleeve necessary for assembling the recycled fuel assembly storage container is secured, and thereafter, the cylinder body when the recycled fuel assembly is stored using the difference in thermal expansion between the cylinder body and the sleeve. It is also possible to minimize the gap for improving the heat transfer between the sleeve and the sleeve. At the same time, the shake between the trunk body and the sleeve when the recycled fuel assembly storage container is dropped can be extremely reduced.

  The recycled fuel assembly storage container according to the second embodiment has substantially the same configuration as the recycled fuel assembly storage container according to the first embodiment, but the joint between the flange and the sleeve main body is connected to the joint between the flange and the sleeve. The shape of the stress relaxation portion provided between the two is different. Since other configurations are the same as those of the first embodiment, description thereof is omitted.

FIG. 11 is an enlarged view of the recycled fuel assembly storage container according to the second embodiment before joining the flange mounting portion. Also in the recycled fuel assembly storage container 200a according to the second embodiment, from the joint portion (second joint portion W ₂ ) between the flange 211 and the sleeve 220, the joint portion (first joint) between the flange 211 and the trunk body 201t ′. Between the portions W ₁ ), there are provided stress relaxation portions 251 that relieve the bending stress generated at the joint between the flange 211 and the sleeve 220.

In the second embodiment, the point C is between the joint portion (second joint portion W ₂ ) between the flange 211 and the sleeve 220 and the joint portion (first joint portion W ₁ ) between the flange 211 and the trunk body 201t ′. _A stress relieving portion 251 is provided that includes a curved surface shape having a radius r ₂ centered at _2, a curved surface shape having a radius r ₁ centered at the point C ₁ , and a planar shape connecting the two. Thereby, the bending stress generated at the joint between the flange 211 and the sleeve 220 is relaxed, and the soundness of the joint between the flange 211 and the sleeve 220 is ensured.

  In the first embodiment, the stress relieving part 250 is composed of only a curved surface. However, as in the second embodiment, a combination of a curved surface and a flat surface may be used. That is, if the stress relaxation portion is configured to include a curved surface having a certain radius, the bending stress generated at the joint portion between the flange 211 and the sleeve 220 can be relaxed. And the soundness of the junction part of the flange 211 and the sleeve 220 can be ensured. In addition, since the stress relaxation part 251 of Example 2 contains a plane, there also exists an advantage that manufacture becomes easy.

At this time, it is preferable that the radii r ₁ and r _{2 on} the curved surface of the stress relaxation portion are both 1/6 or more and 3/4 or less of the radial thickness ΔR (= Ro−Ri) of the flange. Further, the point C ₂ that is the center of the curved surface formed on the sleeve mounting side of the stress relaxation portion is provided at a position of a predetermined size hc2 from the sleeve joint end surface 211st of the flange 211 toward the primary lid mounting end surface 211bt. It is preferable.

  The recycled fuel assembly storage container according to Example 3 has substantially the same configuration as the recycled fuel assembly storage container according to Examples 1 and 2, but the diameter of the step portion provided at the joint between the flange and the trunk body The difference is that the direction contact surface is inclined toward the radially outer side of the flange with respect to the flange central axis. Since other configurations are the same as those in the first and second embodiments, description thereof is omitted.

  FIG. 12-1 is an enlarged view of the recycled fuel assembly storage container according to the third embodiment before joining the flange mounting portion. FIG. 12-2 is an enlarged view of the flange mounting portion of the recycled fuel assembly storage container according to the third embodiment. A flange-side step portion 212d formed in a step shape is provided at a portion where the flange 212 provided in the recycled fuel assembly storage container 200b according to the third embodiment is combined with the opening portion 201to ″ of the trunk body 201t ″. ing. The flange-side radial contact surface 212dp formed on the flange-side step portion (second step portion) 212d has a flange radius R larger on the sleeve joint end surface 210st than on the primary lid attachment end surface 212B1t. It is inclined with respect to the flange axis Zf by an inclination angle θ.

'First joined section W ₁ near, i.e. trunk body 201t' trunk body 201t 'to' opening 201to the '', adapted to the stepped portion 212d of the flange 212, i.e., the barrel shape is combined with the stepped portion 212d A main body side step portion (first step portion) 201td '' is provided. For this reason, the trunk body side radial contact surface 201tdp '' formed on the trunk body side step 201td '' is inclined by an inclination angle θ with respect to the axis Z (flange axis Zf) of the recycled fuel assembly storage container. doing.

'When joining the first joining portion W _1, the flange-side stepped portion 212d and the trunk body side step 201Td' flange 212 and the trunk body 201t '' and are combined, a meshing configuration. Thereby, when the stainless steel flange 212 is thermally expanded in the radial direction (direction indicated by RR in FIG. 12-2) due to the decay heat of the recycled fuel assembly, the flange side radial contact surface 212dp and the body side The radial contact surface 201tdp ″ contacts. Thereby, the thermal expansion of the flange 212 is restrained by the trunk body side step portion 201td ″.

Further, the pulling force generated at the first joint portion W _{1 due} to the thermal expansion of the flange 212 can be reduced by the inclination angle θ provided on the flange side radial contact surface 212dp. Further, when the flange 212 is thermally expanded, the flange-side radial contact surface 212dp and the trunk body-side radial contact surface 201tdp ″ contact with a stronger force due to the inclination angle θ. Thus, the tensile stress generated in the first joined section W ₁ by thermal expansion of the flange 212 can be further reduced, it is possible to further reduce the radial length of the first joint portion W _1.

By these actions, the stress of the first joint W ₁ generated due to the thermal expansion of the flange 212 can be further reduced, so that the soundness of the first joint W ₁ can be sufficiently ensured. In particular, this structure is more suitable for housing a PWR recycled fuel assembly having a high burnup and a large calorific value. The inclination angle θ is preferably about 5 degrees or more and 10 degrees or less. The flange 212 and the trunk main body 201t ″ are structures that relieve the stress of the first joint W ₁ by a structure that meshes with the direction of thermal expansion of the flange 212. It is possible to effectively relieve the stress at one joint W ₁ . Further, the flange 212 is expanded and incorporated by, for example, heating the trunk body 201t ″. If the inclination angle θ is in the above range, a predetermined value is required when the flange 212 is incorporated into the trunk body 201t ″. Clearance can be secured.

  As described above, the recycle fuel assembly storage container according to the present invention is useful for transporting and storing the recycle fuel assembly, and in particular, the double structure recycle fuel assembly storage container having a sleeve inside the trunk body. Suitable for

1 is an overall view showing a recycled fuel assembly storage container according to Embodiment 1. FIG. FIG. 2 is a cross-sectional view parallel to the axial direction of the recycled fuel assembly storage container shown in FIG. 1. FIG. 3 is an XX arrow view of FIG. 2. It is an enlarged view of the part shown by B of FIG. It is an enlarged view which shows the clearance of a sleeve and a trunk | drum main body. 6 is a plan view showing another example of a flat plate constituting the outer cylinder of the recycled fuel assembly storage container according to Embodiment 1. FIG. It is the figure seen from the arrow C direction of FIGS. 6 is a plan view showing another configuration of the outer cylinder of the recycled fuel assembly storage container according to Embodiment 1. FIG. It is explanatory drawing which shows an example of the basket which accommodates a recycle fuel assembly. It is sectional drawing which shows an example of the basket which accommodates a recycle fuel assembly. It is an enlarged view of the flange attaching part of the recycle fuel assembly storage container concerning Example 1. FIG. It is an enlarged view before joining of the flange attaching part of the recycle fuel assembly storage container concerning Example 1. FIG. It is sectional drawing parallel to the axis | shaft of a flange. It is a top view at the time of seeing a flange from the arrow D direction of FIGS. It is an enlarged view before joining of the flange attaching part of the recycle fuel assembly storage container concerning Example 2. It is an enlarged view before joining of the flange attaching part of the recycle fuel assembly storage container concerning Example 3. 6 is an enlarged view of a flange mounting portion of a recycled fuel assembly storage container according to Embodiment 3. FIG.

Explanation of symbols

200, 200a, 200b Recycled fuel assembly storage container 200B Body 200T Lid 201c Cavity 201t Body body 201td Body body side step part 210, 211, 212 Flange 210d, 212d Flange side step part 220 Sleeve 250, 251 Stress relaxation part 300 Basket

Claims (8)

A cylindrical body is provided with a bottom at one end and an opening at the other end, and a trunk body in which a first step is formed inside the opening;
A sleeve made of a material different from that of the trunk body and disposed in the trunk body to store the recycled fuel assembly; and a sleeve having a thickness smaller than the thickness of the trunk portion;
A portion that is a cylindrical member that is combined with the opening of the trunk main body is a portion that is in contact with an end of the opening while a second step is formed in accordance with the shape of the first step. And a flange made of the same material as the sleeve, wherein the end of the sleeve is fixed to the end on the inner peripheral side and the bottom side,
A lid attached to the opening side of the flange;
A recycle fuel assembly storage container comprising:   The stress relaxation part comprised including a curved surface is provided between the fixing | fixed part of the said flange and the said sleeve, and the fixing | fixed part of the said flange and the said trunk | drum main body. Recycled fuel assembly storage container.   The recycled fuel assembly storage container according to claim 2, wherein a radius of a curved surface constituting the stress relaxation portion is not less than 1/6 and not more than 3/4 of a radial thickness of the flange.   The recycled fuel assembly storage container according to any one of claims 1 to 3, wherein a predetermined clearance is provided between the sleeve and the bottom of the cavity.   The recycled fuel assembly storage container according to any one of claims 1 to 4, wherein the flange and the lid are made of the same material.   The recycled fuel assembly storage container according to claim 1, wherein the sleeve and the flange are made of stainless steel. A cylindrical body is provided with a bottom at one end and an opening at the other end, and a trunk body in which a first step is formed inside the opening;
The sleeve is made of a material different from that of the trunk body and is disposed in the trunk body to store the recycled fuel assembly, and further, a sleeve having a thickness smaller than the thickness of the trunk portion,
A cylindrical member that is fixed to the trunk main body at a portion that contacts the end of the opening, and that the end of the sleeve is fixed to the inner peripheral side and the end on the bottom side. A flange made of the same material as the sleeve;
A lid attached to the opening side of the flange,
A recycling characterized in that a stress relieving portion including a curved surface is provided between a portion to which the flange and the sleeve are fixed and a portion to which the flange and the trunk body are fixed. Fuel assembly storage container.   The recycled fuel assembly storage container according to claim 7, wherein a radius of a curved surface constituting the stress relaxation portion is not less than 1/6 and not more than 3/4 of a radial thickness of the flange.

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