JP6239475B2 - Manufacturing method of fuel channel box, fuel assembly, and core of boiling water reactor loaded with the same - Google Patents

Description

  The present invention relates to a fuel channel box, and relates to a fuel channel box manufacturing method capable of reducing clip welding corrosion and improving productivity, a fuel assembly, and a core of a boiling water reactor (BWR) loaded with the fuel assembly. .

  In a boiling water nuclear power plant in Japan, corrosion defects were found in the clip welds of the fuel channel box. This deficiency is presumed to be caused by a decrease in the corrosion resistance of the weld due to clip welding with a high heat input (current × voltage ÷ welding speed).

  Clip welding is complete penetration welding as a measure against crevice corrosion in the nuclear reactor, and the amount of back wave of the welding is also limited due to fuel contact. In addition, the fuel channel box uses a thin plate of zirconium, and it is necessary to pay attention to burn-out due to welding and to make stable welding. In order to satisfy these requirements, welding resulted in a high heat input, resulting in a decrease in the corrosion resistance of the weld. In order to solve these problems, we are developing welding equipment that realizes welding with low heat input and selecting welding conditions that achieve low heat input.

  There exists patent document 1 as a conventional fuel channel box. In Patent Document 1, a zirconium alloy plate material is formed and welded to form a rectangular tube, and then a clip is welded to the opening side end of the fuel channel box of the rectangular tube and brought into contact with the metal alkoxide-containing solution. Metal oxide films are formed on the inner and outer surfaces of the box. In Patent Document 1, a clip is formed from a zirconium alloy plate material that forms a rectangular tube, and this clip is welded to the end of the rectangular tube. The thickness of the fuel channel box (the plate of the rectangular tube) Thickness) and the clip thickness are the same. Stable clip welding is realized by aligning the outer periphery of the welding surface of the clip with the outer shape of the rectangular tube.

  In addition, in response to the Great East Japan Earthquake, we are also considering increasing the thickness of the fuel channel box in order to prevent deformation of the fuel channel box due to massive earthquake motion. That is, the fuel channel box may be thickened.

JP 2001-99970 A

  As described above, the fuel channel box will become thicker (increase in plate thickness) in the future. However, if the plate thickness of the fuel channel box and the plate thickness of the clip are the same as in Patent Document 1, the heat input amount associated with the increase in the plate thickness of the channel box is required when complete penetration welding is performed in the plate thickness direction of the clip. The increase is unavoidable, and the corrosion of the clip welds of the fuel channel box may occur.

  An object of the present invention is to provide a method of manufacturing a fuel channel box that can reduce the corrosion of the clip welded portion regardless of the plate thickness of the fuel channel box.

  Further, the present invention reduces the loss of the clip welded portion regardless of the plate thickness of the fuel channel box constituting the fuel assembly, and can improve the reliability when the fuel assembly is inserted into and removed from the core. And providing a core of a boiling water reactor to which it is loaded.

  In order to solve the above-mentioned problems, a method for manufacturing a fuel channel box according to the present invention comprises forming a zircaloy plate material in a U-shaped cross section and welding the two zircaloy plate materials formed in the U-shape to form a rectangular tubular fuel. A method of manufacturing a fuel channel box forming a channel box, comprising: (1) inserting one corner of a rectangular tubular fuel channel box welded to the two plate members into a cooling positioning jig; (2) placing and positioning a clip thinner than the plate thickness of the fuel channel box at one corner contacting the cooling positioning jig; and (3) welding the positioned clip by welding. Joining to the fuel channel box.

The fuel assembly of the present invention includes a plurality of fuel rods filled with nuclear fuel material in a cladding tube, and a columnar one that holds the upper end portions of the plurality of fuel rods and stands upright on the outer peripheral portion of the upper surface. An upper tie plate having a plurality of fuel rods, a lower tie plate for holding lower ends of the plurality of fuel rods, a spacer for arranging the plurality of fuel rods in a lattice shape on a cross section, and the plurality of fuel rods, an upper portion A rectangular tubular fuel channel box that accommodates a tie plate, a lower tie plate, and a spacer, and an opening end of the fuel channel box has a clip that is joined to two diagonal corners by welding. and, with a through hole formed in the hand of the clip the upper tie plate of the post therethrough, the two thickness clip to said thinner than the thickness of the fuel channel box .

  Also, the core of the boiling water reactor of the present invention is a boiling unit in which a plurality of fuel assemblies each containing a plurality of fuel rods filled with nuclear fuel material in a cladding tube are arranged in a fuel cell box and loaded. In the core of the water reactor, the open end of the fuel channel box has clips that are joined to two diagonal corners by welding, and the thickness of the two clips is the thickness of the fuel channel box. It is thinner than the plate thickness.

  According to the present invention, it is possible to provide a fuel channel box that can reduce the corrosion of the clip welded portion regardless of the plate thickness of the fuel channel box, and to improve the productivity of the fuel channel box.

  In addition, according to the present invention, the fuel assembly capable of reducing the loss of the clip welded portion and improving the reliability when the fuel assembly is inserted into and removed from the core regardless of the plate thickness of the fuel channel box, and loading the same. A core of a boiling water reactor can be provided.

  Problems, configurations, and effects other than those described above will be clarified by the following description of embodiments.

It is a schematic block diagram of a boiling water nuclear power plant. It is a longitudinal cross-sectional view of the fuel assembly which concerns on one Embodiment of this invention. FIG. 3 is an AA sectional view of the fuel assembly shown in FIG. 2. It is a cross-sectional perspective schematic diagram which shows the cladding tube of the fuel rod shown in FIG. It is a cross-sectional perspective schematic diagram which shows the cladding tube of the water rod shown in FIG. FIG. 3 is a cross-sectional view of the fuel assembly shown in FIG. It is a figure which shows the schematic manufacturing process of the fuel channel box which concerns on one Embodiment of this invention shown in FIG. It is a figure which shows the relationship between the plate | board thickness of the fuel channel box of Example 1 which concerns on one Example of this invention, and the heat input of clip welding with a prior art example. It is a figure which shows the arrangement | positioning relationship between the holeless clip and square tube of Example 1 which concern on one Example of this invention. It is explanatory drawing of the positioning process of the clip with a hole of Example 1 which concerns on one Example of this invention. It is a figure which shows the arrangement | positioning relationship between the holeless clip of Example 2 which concerns on the other Example of this invention, and a square tube. It is explanatory drawing of the positioning process of the clip with a hole of Example 2 which concerns on the other Example of this invention. It is a figure which shows the arrangement | positioning relationship between the holeless clip of Example 3 which concerns on the other Example of this invention, and a square tube. It is explanatory drawing of the positioning process of the holey clip of Example 3 which concerns on the other Example of this invention.

  The inventors of the present invention have a heat input of clip welding that requires complete penetration welding as H = 60 × E × I / v (J / cm), where H is the heat input during full penetration welding, E Is the arc voltage, I is the arc current, and v is the welding speed (cm / min). As a result of intensive research, the clip thickness is made smaller than the thickness of the fuel channel box to reduce the heat input. The present inventors have obtained a new finding that defects due to corrosion in a clip weld can be reduced. Hereinafter, a boiling water reactor in which a fuel assembly using the fuel channel box of the present invention is loaded will be described.

  FIG. 1 shows a schematic configuration diagram of a boiling water nuclear power plant using a fuel channel box according to an embodiment of the present invention. The boiling water nuclear power plant 1 includes a nuclear reactor 2 and a reactor containment vessel 3. The reactor containment vessel 3 is installed in the reactor building 4, and a reactor containment vessel upper lid 5 is attached to an upper end portion of the reactor containment vessel 3 so as to be sealed. The reactor containment vessel 3 has a dry well 6 formed therein and a pressure suppression chamber (wet well) 7 in which a pressure suppression pool filled with cooling water is formed. One end of the vent passage 8 connected to the dry well 6 is immersed in the cooling water of the pressure suppression pool in the pressure suppression chamber 7. A shield plug 9, which is a radiation shield divided into a plurality of parts, is disposed directly above the reactor containment vessel upper lid 5, and these shield plugs 9 are installed on the operation floor 29 of the reactor building 4.

  The reactor containment vessel 3 is installed inside the reactor building 4, and the lid of the reactor pressure vessel 11 is opened at the top of the reactor containment vessel 3 when the reactor is stopped, and the fuel assembly 16 is placed. It is a pool through which it is taken out and moved to the adjacent spent fuel storage pool 28, and is provided with a reactor well 26 for filling water for shielding radiation or the like. The fuel assembly 16 is taken out and transferred to the spent fuel pool 28 by the fuel exchanger 30. Further, a dryer / separator pool 27 and a spent fuel storage pool 28 for temporarily storing spent fuel are provided so as to sandwich the reactor well 26. The dryer / separator pool 27 is used as a place for temporarily placing furnace internal equipment such as the steam dryer 14 and the steam / water separator 13 during periodic inspection.

  Reactor 2, reactor pressure vessel 11 configured by attaching a reactor pressure vessel top lid 10, a core 12 loaded with a plurality of fuel assemblies 16 containing nuclear fuel materials, a steam dryer 14 and a steam / water separator 13 It has. The core 12, the steam dryer 14, and the steam / water separator 13 are disposed in the reactor pressure vessel 11. A core shroud 15 installed in the reactor pressure vessel 11 surrounds the core 12. Each fuel assembly 16 loaded in the core 12 has a lower end supported by the core support plate 17 and an upper end held by the upper lattice plate 18. The steam / water separator 13 is disposed above the upper lattice plate 18 located at the upper end of the core 12, and the steam dryer 14 is disposed above the steam / water separator 13. Here, the fuel assembly 16 has a fuel rod in which a plurality of pellets of MOX fuel, for example, as a nuclear fuel material (not shown) are filled in a stainless steel cladding tube in the axial direction. A fuel assembly 16 is formed by arranging a plurality of fuel rods in a square lattice shape in a channel box having a quadrangular cross section.

  A plurality of control rod guide tubes 19 are arranged below the core 12, and a support cylinder including the plurality of control rod guide tubes 19 is formed. Control rods 20 that are taken in and out between the fuel assemblies 16 in the core 12 and control the reactor power are disposed in the control rod guide tubes 19. A plurality of control rod drive mechanism housings 21 are attached to the lower mirror 22 of the reactor pressure vessel 11. A control rod drive mechanism (not shown) is installed in each control rod drive mechanism housing 21 and connected to the control rod 20 in the control rod guide tube 19. A steam dryer 14, a steam separator 13, a core shroud 15, an upper lattice plate 18, a core support plate 17, a support cylinder, a control rod guide tube 19, a core shroud lower shell installed in the reactor pressure vessel 11 are It is a furnace internal structure.

  The reactor pressure vessel 11 is installed on a cylindrical pedestal 24 provided on a concrete mat 23 provided at the bottom of the reactor containment vessel 3. A cylindrical gamma ray shield 25 is installed at the upper end of the pedestal 24 and surrounds the reactor pressure vessel 11.

  Here, the configuration of the fuel assembly 16 will be described. As shown in FIG. 2, the fuel assembly 16 bundles an upper tie plate 31, a lower tie plate 32, a plurality of fuel rods 33 held at both ends of these tie plates, a water rod 34, and these fuel rods. A fuel support grid (spacer) 35 and a fuel channel box 36 surrounding the fuel rod bundle bundled by the fuel support grid 35 and attached to the upper tie plate 31 are provided. A handle 38 is fastened to the upper tie plate 31. When the handle 38 is lifted, the entire fuel assembly 16 can be pulled up. As the fuel rod, a partial-length fuel rod 37 whose height does not reach the upper tie plate 31 may be employed. In other words, the partial-length fuel rod 37 is a fuel rod having a shorter effective fuel length filled inside than the full-length fuel rod 33 reaching the upper tie plate 31. The upper tie plate 31 is provided with a single post 39 that passes through a hole of a clip, which will be described later, and is connected to the fuel channel box 36 through the clip.

  As shown in FIG. 3, full-length fuel rods 33, partial-length fuel rods 37, and water rods 34 are bundled and accommodated in a square lattice shape in a fuel channel box 36 having a rectangular cross section. Here, an example is shown in which two water rods 34 are arranged at the substantially central portion of the cross section of the fuel channel box 36 and each water rod 34 is arranged in a lattice region where four full length fuel rods 33 can be arranged. .

  In the core 12 of the nuclear reactor 2, the fuel assembly 16 is supported by a core support plate 17 and an upper lattice plate 18 and is surrounded by a cylindrical core shroud 15. From below, the cooling water flows into the rectangular tubular fuel channel box 36 via the orifice of the fuel support fitting and the lower tie plate 32 of the fuel assembly 16, is heated by the fuel rod 33, and is vaporized by boiling. To generate a gas-liquid two-phase flow.

  FIG. 4 is a schematic cross-sectional perspective view showing a fuel cladding tube in the full length fuel rod 33 shown in FIG. 2, and FIG. 5 is a schematic cross-sectional perspective view showing a cladding tube of the water rod 34. The fuel cladding tube 41 shown in FIG. 4 uses, for example, a SiC / SiC composite material as a base material, and an appropriate environmental shielding coating is applied to the surface. The end plug 44 is made of a sintered ceramic made of SiC reinforced fiber or a Zr alloy. The fuel cladding tube 41 has an outer diameter of about 11 mm and a tube thickness of about 1 mm. The end plug 44 is a solid bar. A fuel pellet 42 is accommodated in the fuel cladding tube 41, and one end plug 44 held on the upper tie plate 31 has one end connected to the bottom of the end plug 44 and the other end connected to the fuel cladding tube 41. A plenum spring 43 is provided so as to restrain the uppermost portion of the fuel pellets 42 accommodated therein. The upper tie plate 31 is formed with only one cylindrical post 39 with a thread. The post 39 passes through a hole of a holed clip, which will be described later, and is screwed to the clip. Therefore, the fuel channel box 36 is connected to the upper tie plate 31 only by this post 39.

  Further, the water rod 34 shown in FIG. 5 includes a hollow tube 45 through which cooling water flows, an end plug 46 held by the lower tie plate 32 and the upper tie plate 31, and the hollow tube 45 at the center in the axial direction. It has the area | region 47 used as the diameter smaller than the diameter of a part. The hollow tube 45 uses, for example, a SiC / SiC composite material as a base material, and has an appropriate environmental shielding coating on the surface. The end plug 46 is made of a sintered ceramic made of SiC reinforced fiber or a Zr alloy.

  FIG. 6 is a cross-sectional view of the fuel assembly shown in FIG. In FIG. 6, as described above, the post 39 and the upper tie plate 31 that pass through the hole of the holed clip 51 are omitted for convenience of explanation. As shown in FIG. 6, among the fuel assemblies 16 loaded in a lattice pattern on the core 12 of the reactor 2, a control rod 20 having a substantially cross-shaped cross section is arranged at the center of the four fuel assemblies 16. A plurality of local output region monitors are arranged to detect the neutron flux.

  The square tube (fuel channel box) 50C made of Zircaloy has the above-mentioned two in order to maintain the distance between the fuel assemblies 16 adjacent in the core 12 at the upper ends of the two side surfaces facing the control rod 20. A channel spacer 48 is attached near the upper end of the side surface by welding. A zircaloy holed clip 51 and a holeless clip 52 are attached to two corners on the diagonal line by welding at the upper end of the opening of the rectangular tube (fuel channel box) 50C. The holed clip 51 and the holeless clip 52 are for resisting stress generated in the radial direction of the core 12 with respect to the rectangular tube (fuel channel box) 50C, that is, in the direction perpendicular to the axial direction of the fuel assembly 16. It functions as a reinforcing material. Further, as described above, the holed clip 51 has a function of connecting the upper tie plate 31 to the rectangular tube 50C via the post 39 formed on the upper tie plate 31. Here, the plate thickness of the holed clip 51 and the holeless clip 52 of the present invention is thinner than the plate thickness of the rectangular tube 50C. The details of the shape and plate thickness of the holed clip 51 will be described later in Examples.

  FIG. 7 shows a schematic manufacturing process of the fuel channel box according to the embodiment of the present invention. First, as shown in the uppermost drawing of FIG. 7, a Zircaloy plate material 50A, which is a Zircaloy flat plate, is prepared (Step 1). Here, the thickness of the Zircaloy plate material 50A is about several mm. Next, the zircaloy plate material 50A is processed into a U-shaped cross section macroscopically and a U-shaped cross section microscopically by pressing (step 2). Below, it demonstrates as a U-shaped cross section. In step 2, two zircaloy plate members 50B having a U-shaped cross section are formed. Thereafter, these two zircaloy plate members 50B having a U-shaped cross section are joined by welding to form a rectangular tube 50C (step 3). A channel spacer 48 is joined by welding near the upper end portions of the two side surfaces of the rectangular tube 50C. In addition, a holed clip 51 and a holeless clip 52 are respectively positioned at two corners in the diagonal direction of the upper end of the opening of the rectangular tube 50C, that is, two corners on the diagonal, and the rectangular tube is formed by complete penetration welding. The holed clip 51 and the holeless clip 52 are joined to the tube 50C to form a fuel channel box (step 4). In step 4, the joining order of the channel spacer 48, the holed clip 51 and the holeless clip 52 by welding may be reversed.

  According to the fuel assembly 16 according to the embodiment of the present invention having the holed clip 51 and the holeless clip 52 which are thinner than the plate thickness of the rectangular tube 50C formed in this way, the loss of the clip welded portion is reduced. Thus, when the fuel assembly 16 is pulled out from the core 12, the holed clip 51 is peeled off, and the fuel rod 33, the partial length fuel rod 37 and the water rod held between the upper tie plate 31 and the lower tie plate 33 are separated. As a result, it is possible to prevent the rectangular tube 50C from dropping off and to realize a highly reliable fuel assembly.

  Further, by loading the fuel assembly 16 on the core 12 of the boiling water reactor, for example, when the fuel assembly 16 is pulled out of the core 12, the clip 51 with holes is peeled as described above, A situation (loose parts) remaining in the core 12 together with the tube 50C can be prevented, and a highly reliable boiling water reactor core can be realized.

  Embodiments of the present invention relating to the shape of the holed clip 51 and details of positioning of the holed clip 51 will be described below with reference to the drawings.

  FIG. 9 shows an arrangement relationship between the holeless clip 52A and the rectangular tube 50C according to the first embodiment of the present invention. As shown in FIG. 9, a cooling positioning jig 54A also serving as a cooling function at the time of welding is disposed inside the corner portion of the rectangular tube 50C, and the holeless clip 52A and the clip 52A are provided on the cooling positioning jig 54A. A positioning jig (second clip positioning jig) 53 having a notch simulating a substantially triangular apex portion of the holeless clip 52A is disposed. As shown in FIG. 9, the notch of the positioning jig 53 is fitted on the substantially triangular apex of the holeless clip 52A and the upper end of the rectangular tube 50C, and the cooling positioning jig 54A Cooperate to position the holeless clip 52A.

  The holeless clip 52A is a substantially triangular flat plate made of Zircaloy, and has a stepped shape by notching both ends of the bottom portion facing the apex portion. Further, a portion (a side surface on the center side of the cross section of the rectangular tube 50C of the holeless clip 52A) of the bottom side portion of the holeless clip 52A excluding the stepped portion formed at both ends is provided on the cooling positioning jig 54A. It can come into contact with the provided step portion. The plate thickness T1 of the holeless clip 52A and the plate thickness T2 of the rectangular tube 50C are in a relationship of T1 / T2 = 1/2. Moreover, the width W of the joint surface joined by welding to the upper end portion of the square tube 50C of the holeless clip 52A is equal to T1. That is, the width W of the joining surface is ½ of the plate thickness of the rectangular tube 50C.

  Here, FIG. 8 shows the relationship between the plate thickness (T2) of the fuel channel box (square tube) and the heat input amount of clip welding together with the conventional example. The horizontal axis indicates the thickness T2 (mm) of the fuel channel box (square tube 50C), the vertical axis indicates the heat input (J / cm) of clip welding, and the circle and triangle marks indicate values obtained by conventional clips, and the diamond marks Shows the values obtained by the holeless clip 52A of the present embodiment. The plate thickness T1 of the holeless clip 52A of this embodiment is fixed at 2.05 mm, and the plate thickness (T1) of the conventional clip is the same as the plate thickness (T2) of the fuel channel box.

  As shown in FIG. 8, in the conventional clip, when the thickness T1 of the clip is 2.05 mm, the thickness T2 of the fuel channel box is 2.05 mm, and the heat input is 7000 J / cm, a defect occurs in the clip welded portion. No. Also, when the clip plate thickness T1 is 2.54 mm, the fuel channel box plate thickness T2 is 2.54 mm, and the heat input is 9000 J / cm, no defects are observed in the clip welds, and the heat input is the same plate thickness. At 1600 J / cm, a defect in the welded portion of the clip was confirmed. Further, when the plate thickness T1 of the clip was 3.05 mm, the plate thickness T2 of the fuel channel box was 3.05 mm, and the heat input amount was 11000 J / cm, no defect in the clip weld was confirmed.

  On the other hand, in this embodiment, the clip thickness T1 is 2.05 mm, the fuel channel box thickness T2 is 2.54 mm, the heat input is 7000 J / cm, and no defects in the welded portion of the clip are confirmed. Even if the plate thickness T1 of the clip was 2.05 mm, the plate thickness T2 of the fuel channel box was 3.05 mm, and the heat input was 7000 J / cm, no defects were found in the welded portion of the clip.

  As described above, in order to completely melt and weld the clip, it is necessary to melt the clip in the thickness direction. In the case of the conventional clip, it is necessary to increase the thickness T1 of the clip as the thickness T2 of the fuel channel increases. is there. If the plate thickness T1 of the clip increases, it is necessary to increase the heat input accordingly. However, according to the present embodiment, even if the plate thickness T1 of the clip is kept constant at 2.05 mm and the plate thickness T2 of the fuel channel box increases to 2.54 mm and 3.05 mm, the heat input is the same, 7000 J / It can be seen from FIG. 8 that complete penetration welding with a low heat input of cm is possible. Therefore, according to the present Example, the generation | occurrence | production of the defect | deletion in a clip welding part can be reduced.

  Note that when the plate thickness T1 of the holeless clip 52A and the holed clip 51A is 1 mm or less, there is no problem in the joining strength due to welding, but the difficulty of the welding operation is dramatically improved. Therefore, the plate thickness T1 of the holeless clip 52A and the holed clip 51A is preferably greater than 1 mm. Further, when the plate thickness T2 of the fuel channel box (square tube 50C) is set to 3.05 mm at the maximum, it is preferable to satisfy 1/3 ≦ T1 / T2 ≦ 4/5. Considering workability, it is desirable that T1 / T2 = 1/2. Further, W <T2 is preferable, and W1 = T1 is preferable.

  FIG. 10 shows a positioning step of the clip with a hole according to the first embodiment of the present invention. In FIG. 10, the front view is shown on the left side, and the AA cross-sectional arrow view of the front view is shown on the right side.

  As shown in FIG. 10A, the rectangular tube 50C is inserted into a cooling positioning jig 54A having a substantially triangular prism shape. As shown in the front view and the cross-sectional view, the cooling positioning jig 54A has an opening in which a female thread is cut on the bottom side facing the substantially triangular apex angle, and above the position where the opening is located. A step is formed. By inserting the rectangular tube 50C into the cooling positioning jig 54A, the rectangular tube 50C is positioned in a self-aligning manner with the cooling positioning jig 54A by the weight of the rectangular tube 50C (self-alignment).

  Next, as shown in FIG. 10B, the holed clip 51A is placed on the cooling positioning jig 54A and the upper end of the rectangular tube 50C. Here, the holed clip 51A is a substantially triangular flat plate made of Zircaloy, and both ends of the bottom part facing the apex corner part are cut out to form a stepped shape, and the post 39 penetrates and can be screwed. It has a hole. In addition, a portion (a side surface on the central side of the cross section of the rectangular tube 50C of the holed clip 51A) of the bottom side part of the holed clip 51A excluding the stepped portion formed at both ends is provided on the cooling positioning jig 54A. When placed, the cooling positioning jig comes into contact with the step provided on 54A. Subsequently, a positioning jig (second clip positioning jig) 53 is placed on the upper end of the square tube 50C above the holed clip 51A. The notch portion of the positioning jig 53 is fitted on the substantially triangular apex portion of the holed clip 51A and the upper end of the rectangular tube 50C, and the holed clip 51A is positioned with the cooling positioning jig 54A. The tool 53 is positioned.

  Next, as shown in FIG. 10C, a threaded plate-like pressing member 55 having a substantially triangular plate shape and having a male screw near the bottom is attached. At this time, the male screw of the threaded plate-like pressing member 55 is screwed into the opening in which the female screw provided in the cooling positioning jig 54A is cut. Thus, the positioned holed clip 51A is fixed to the cooling positioning jig 54A and the upper end of the rectangular tube 50C.

  Subsequently, as shown in FIG. 10 (d), the positioning jig (second clip positioning jig) 53 is removed, and the holed clip 51A is attached to the upper end portion of the rectangular tube 50C by welding.

  As shown in FIG. 10 (e), after the holed clip 51A is joined to the upper end of the rectangular tube 50C by full penetration welding, the threaded plate-like pressing member 55 is removed.

  In addition, the holeless clip 52A attached to the diagonal direction of the holed clip 51A rotates the rectangular tube 50C by 180 ° after the step shown in FIG. 10 (e), from FIG. 10 (a) to FIG. 10 (e). By repeating the process shown, it is attached to the upper end of the rectangular tube 50C by complete penetration welding.

  According to the present embodiment, the holed clip 51A and the holeless clip 52A having a plate thickness thinner than that of the rectangular tube 50C can be positioned with high accuracy at the upper end of each tube 50C, and the fuel channel box is produced. Can be improved. In addition, according to the present Example, it becomes possible to use one kind of thin clip having a plate thickness regardless of the increase in the plate thickness of the rectangular tube 50C, and the productivity can be further improved.

  Further, according to the present embodiment, it is possible to reduce the amount of heat input when welding the holed clip 51A and the holeless clip 52A, and it is possible to reduce defects due to corrosion in the clip welded portion.

  FIG. 11 shows an arrangement relationship between the holeless clip 52A and the square tube 50C according to the second embodiment of the present invention, and FIG. 12 shows a positioning process of the holed clip 51A according to the second embodiment of the present invention. The same components as those in the first embodiment are denoted by the same reference numerals. In this embodiment, the shape of the cooling positioning jig is changed to a substantially triangular prism shape, and is changed to a substantially square (trapezoidal) columnar shape, and the holed clip 51A and the holeless clip 52B are positioned using only the cooling positioning jig. This is different from the first embodiment. Since the other points are the same as those in the first embodiment, detailed description thereof is omitted.

  As shown in FIG. 11, the cooling positioning jig 54 </ b> B has a substantially trapezoidal columnar body with a transverse section cut out at a vertex portion having a substantially triangular shape. Two legs of the cooling positioning jig 54B having a substantially trapezoidal cross section, that is, both ends of the cooling positioning jig 54B are in contact with the inner surface of the rectangular tube 50C. In addition, a substantially central portion of the cooling positioning jig 54B has an opening in which an internal thread is cut, and a step is formed on a side of the opening toward the corner of the rectangular tube 50C.

  The holeless clip 52A is a substantially triangular flat plate made of Zircaloy, and has a stepped shape by notching both ends of the bottom portion facing the apex portion. Further, a portion (a side surface on the center side of the cross section of the rectangular tube 50C of the holeless clip 52A) of the bottom side portion of the holeless clip 52A excluding the stepped portion formed at both ends is provided on the cooling positioning jig 54A. It can come into contact with the provided step portion.

  As shown in FIG. 12A, a rectangular tube 50C is inserted into a cooling positioning jig 54B having a columnar body with a substantially trapezoidal cross section. By inserting the rectangular tube 50C into the cooling positioning jig 54B, positioning is performed in a self-aligning manner so that the inner surface of the rectangular tube 50C comes into contact with the legs of the cooling positioning jig 54B due to its own weight. Is done.

  Next, as shown in FIG. 12B, the holed clip 51A is placed on the cooling positioning jig 54B and the upper end of the rectangular tube 50C. Here, the holed clip 51A is a substantially triangular flat plate made of Zircaloy. Both ends of the bottom part facing the apex part are cut out to form a stepped shape, and the post 39 penetrates and can be screwed. It has a hole. Further, a portion (a side surface on the center side of the cross section of the rectangular tube 50C of the holed clip 51A) of the bottom side part of the holed clip 51A excluding the stepped portion formed at both ends is provided on the cooling positioning jig 54B. When placed, the cooling positioning jig comes into contact with the step provided on 54B, and the clip 51A with a hole is positioned with respect to the upper end of the rectangular tube 50C.

  In FIG. 12 (c), a plate-like pressing member 55 with a screw having a substantially triangular plate shape and having a male screw at the center near the bottom is attached. At this time, the male screw of the threaded plate-like pressing member 55 is screwed into the opening in which the female screw provided in the cooling positioning jig 54B is cut. Thus, the positioned holed clip 51A is fixed to the cooling positioning jig 54B and the upper end of the rectangular tube 50C. In this state, the holed clip 51A is attached to the upper end of the rectangular tube 50C by welding.

  Subsequently, as shown in FIG. 12D, after the holed clip 51A is joined to the upper end portion of the square tube 50C by complete penetration welding, the threaded plate-like pressing member 55 is removed. Note that the holeless clip 52A attached in the diagonal direction of the holed clip 51A rotates the square tube 50C by 180 ° after the step shown in FIG. 12 (d), from FIG. 12 (a) to FIG. 12 (d). By repeating the process shown, it is attached to the upper end of the rectangular tube 50C by complete penetration welding.

  According to the present embodiment, in addition to the effects of the first embodiment, the holed clip 51A and the holeless clip 52A are positioned with respect to the rectangular tube 50C having various thicknesses by using one type of cooling positioning jig 54B. In addition, the productivity of the fuel channel box can be improved. Further, the positioning jig 53 in the first embodiment is not necessary, and the work process can be shortened.

  FIG. 13 shows the positional relationship between the holeless clip 52B and the square tube 50C according to the third embodiment of the present invention, and FIG. 14 shows the positioning process of the holed clip 51B according to the third embodiment of the present invention. The same components as those in the second embodiment are denoted by the same reference numerals. The present embodiment is different from the second embodiment in that the shape of the holeless clip 52B and the holed clip 51B is changed to a substantially trapezoidal flat plate instead of a substantially triangular flat plate.

  As shown in FIG. 13, the holeless clip 52B is a substantially trapezoidal flat plate with a substantially triangular apex portion cut out. Two legs of the substantially trapezoidal holeless clip 52B are arranged at the upper end of the rectangular tube 50C. The cooling positioning jig 54 </ b> B has a substantially trapezoidal columnar body with a cross section cut out from an apex portion having a substantially triangular shape. Two legs of the cooling positioning jig 54B having a substantially trapezoidal cross section, that is, both ends of the cooling positioning jig 54B are in contact with the inner surface of the rectangular tube 50C. In addition, a substantially central portion of the cooling positioning jig 54B has an opening in which an internal thread is cut, and a step is formed on a side of the opening toward the corner of the rectangular tube 50C. Further, the holeless clip 52B is a substantially trapezoidal flat plate made of Zircaloy, and both ends of the lower bottom thereof are cut out to form a stepped shape. Further, a portion (a side surface on the side of the center of the cross section of the rectangular tube 50C of the holeless clip 52B) of the lower bottom portion of the holeless clip 52B excluding the stepped portion formed at both ends is provided on the cooling positioning jig 54B. It can come into contact with the provided step portion.

  As shown in FIG. 14A, a rectangular tube 50C is inserted into a cooling positioning jig 54B having a columnar body with a substantially trapezoidal cross section. By inserting the rectangular tube 50C into the cooling positioning jig 54B, positioning is performed in a self-aligning manner so that the inner surface of the rectangular tube 50C comes into contact with the legs of the cooling positioning jig 54B due to its own weight. Is done.

  Next, as shown in FIG. 14B, the holed clip 51B is placed on the cooling positioning jig 54B and the upper end of the rectangular tube 50C. Here, the holed clip 51B is a substantially trapezoidal flat plate made of Zircaloy, and is provided with a hole through which both ends of the lower bottom part are cut out to form a stepped shape and through which the post 39 can be screwed. Further, a portion (a side surface on the center side of the cross section of the rectangular tube 50C of the holed clip 51B) of the lower bottom portion of the holed clip 51B excluding the stepped portion formed at both ends is provided on the cooling positioning jig 54B. When placed, the cooling positioning jig comes into contact with the step provided on 54B, and the clip 51B with a hole is positioned with respect to the upper end of the rectangular tube 50C.

  Then, in FIG.14 (c), the plate-shaped press member 55 with a screw which has a substantially triangular plate shape and has an external thread in the center part vicinity of the base is attached. At this time, the male screw of the threaded plate-like pressing member 55 is screwed into the opening in which the female screw provided in the cooling positioning jig 54B is cut. Thus, the positioned holed clip 51B is fixed to the cooling positioning jig 54B and the upper end of the rectangular tube 50C. In this state, the holed clip 51B is attached to the upper end of the rectangular tube 50C by welding.

  As shown in FIG. 14D, after the holed clip 51B is joined to the upper end portion of the square tube 50C by complete penetration welding, the threaded plate-like pressing member 55 is removed. In addition, the holeless clip 52B attached in the diagonal direction of the holed clip 51B rotates the square tube 50C by 180 ° after the step shown in FIG. 14 (d), from FIG. 14 (a) to FIG. 14 (d). By repeating the process shown, it is attached to the upper end of the rectangular tube 50C by complete penetration welding.

  According to the present embodiment, in addition to the effects of the second embodiment, as shown in FIG. 13, compared to the second embodiment, the length of the joint surface by welding of the holed clip 51 </ b> B, that is, the welding distance is shortened. Time can be shortened.

  Moreover, according to the present Example, since a welding part becomes only linear form, the workability | operativity in a welding operation is also improved.

  In addition, this invention is not limited to an above-described Example, Various modifications are included. For example, the above-described embodiments have been described in detail for easy understanding of the present invention, and are not necessarily limited to those having all the configurations described. Further, a part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment. Further, it is possible to add, delete, and replace the configurations of other embodiments with respect to a part of the configurations of the embodiments.

DESCRIPTION OF SYMBOLS 1 ... Boiling water type nuclear power plant, 2 ... Reactor, 3 ... Reactor containment vessel, 4 ... Reactor building, 5 ... Reactor containment vessel top cover, 6 ... Drywell , 7 ... Pressure suppression chamber, 8 ... Vent passage, 9 ... Shield plug, 10 ... Reactor power vessel top cover, 11 ... Reactor pressure vessel, 12 ... Reactor core, 13. .. Steam separator, 14 ... Steam dryer, 15 ... Core shroud, 16 ... Fuel assembly, 17 ... Core support plate, 18 ... Upper lattice plate, 19 ... Control rod guide tube, 20 ... control rod, 21 ... control rod drive mechanism housing, 22 ... lower mirror, 23 ... concrete mat, 24 ... pedestal, 25 ... gamma ray shield , 26 ... Reactor well, 27 ... Dryer / separator pool, 28 ... Spent fuel storage Pool, 29 ... operating floor, 30 ... fuel changer, 31 ... upper tie plate, 32 ... lower tie plate, 33 ... fuel rod, 34 ... water rod, 35 ... Fuel support grid, 36 ... Fuel channel box, 37 ... Partial length fuel rod, 38 ... Handle, 39 ... Post, 41 ... Fuel cladding tube, 42 ... Fuel pellet, 43 ... ..Plenum spring, 44 ... End plug, 45 ... Hollow tube, 46 ... End plug, 47 ... Area, 48 ... Channel spacer, 50A ... Zircaloy plate material, 50B ... · Zircaloy plate material with U-shaped cross section, 50C ··· Square tube (fuel channel box), 51, 51A, 51B · · · clip with holes, 52, 52A and 52B ··· clips without holes, 53 ···・ Positioning jig (No. Clip positioning jig), 54A, 54B ... cooling positioning jig 55 ... threaded plate pressing member

Claims (19)

A method for producing a fuel channel box, wherein a zircaloy plate material is formed in a U-shaped cross section, and two zircaloy plate materials formed in the U shape are welded to form a rectangular tubular fuel channel box,
Inserting one corner of a rectangular tubular fuel channel box welded to the two plate members into a cooling positioning jig;
Placing and positioning a clip thinner than the plate thickness of the fuel channel box at one corner that contacts the cooling positioning jig;
Joining the positioned clip to the fuel channel box by welding. In the manufacturing method of the fuel channel box of Claim 1,
In the positioning step, the width of the joining surface of the clip joined to the fuel channel box by welding is smaller than the plate thickness of the fuel channel box. In the manufacturing method of the fuel channel box of Claim 2,
The positioning step is characterized in that the clip is positioned by a lateral side central side surface of the fuel channel box of the clip coming into contact with a step formed on the surface of the cooling positioning jig. Manufacturing method of fuel channel box. In the manufacturing method of the fuel channel box of Claim 3,
The fuel is characterized in that in the positioning step, the clip is screwed and fixed to the cooling positioning jig by a plate-like pressing member having a screw that can be screwed to an opening formed in the cooling positioning jig. Channel box manufacturing method. In the manufacturing method of the fuel channel box of Claim 4,
The plate-like pressing member has a substantially triangular shape, and the outer peripheral portion of the plate-like pressing member does not overlap the welded portion of the clip,
The method of manufacturing a fuel channel box, wherein the plate-like pressing member is removed from the cooling positioning jig after welding the clip. In the manufacturing method of the fuel channel box of Claim 3,
The method of manufacturing a fuel channel box, wherein the clip joined to the fuel channel box has a substantially triangular shape imitating the shape of one corner of the fuel channel box. In the fuel channel box manufacturing method according to claim 3,
The clip has a substantially trapezoidal shape with a substantially triangular apex cut out, and two legs of the substantially trapezoidal clip are joined to the upper end of the fuel channel box by welding. Channel box manufacturing method. In the manufacturing method of the fuel channel box of Claim 3,
The shape of the region joined to the fuel channel box of the clip is a substantially triangular shape imitating the shape of one corner of the fuel channel box,
By means of a plate-like second positioning jig having a notch that can be fitted on the top corner of the clip and the upper end of the fuel channel box, the clip is placed on the cooling positioning jig and the second positioning jig. A method for manufacturing a fuel channel box, comprising: positioning with a positioning jig. In the manufacturing method of the fuel channel box of Claim 6 or Claim 7,
The cross section of the cooling positioning jig has a substantially trapezoidal shape with a substantially triangular apex portion cut out, and the two legs of the cooling jig whose cross section has a substantially trapezoidal shape are the corners. A method of manufacturing a fuel channel box, comprising contacting an inner surface of a cylindrical tubular fuel channel box. A plurality of fuel rods filled with nuclear fuel material in a cladding;
An upper tie plate having one column-shaped post that holds the upper end portions of the plurality of fuel rods and stands on the outer peripheral portion of the upper surface;
A lower tie plate for holding lower ends of the plurality of fuel rods;
A spacer for arranging the plurality of fuel rods in a lattice shape on a cross section;
A plurality of fuel rods, an upper tie plate, a lower tie plate, and a rectangular tubular fuel channel box that accommodates a spacer,
The open end of the fuel channel box has a clip that is joined to two diagonal corners by welding,
With a through hole formed in the hand of the clip the upper tie plate of the post therethrough, the two thickness clip fuel assembly, characterized in that thinner than the thickness of the fuel channel box. The fuel assembly according to claim 10, wherein
The fuel assembly according to claim 1, wherein a width of a joining surface of the clip joined to an opening end portion of the fuel channel box is smaller than a plate thickness of the fuel channel box. The fuel assembly according to claim 11, wherein
The fuel assembly, wherein the clip joined to the fuel channel box has a substantially triangular shape simulating the shape of one corner of the fuel channel box. The fuel assembly according to claim 11, wherein
The clip joined to the fuel channel box has a substantially trapezoidal shape with a substantially triangular apex cut out, and two legs of the substantially trapezoidal clip are upper end portions of the fuel channel box. A fuel assembly that is joined to the fuel assembly. The fuel assembly according to claim 12 or 13,
When the thickness of the clip is T1, and the thickness of the fuel channel box is T2,
A fuel assembly, wherein 1/3 ≦ T1 / T2 ≦ 4/5. The fuel assembly according to claim 12 or 13,
When the thickness of the clip T1, where the thickness of the fuel channel box T2, the width of the bonding surface of the clip to be joined to the open end portion of the front Symbol fuel channel box of the clip is W,
A fuel assembly characterized in that T1 / T2 = 1/2 and W = T1. In the core of a boiling water reactor in which a fuel assembly that houses a plurality of fuel rods filled with nuclear fuel material in a cladding tube in a fuel channel box is arranged and loaded in a plurality of lattices,
The open end of the fuel channel box has a clip that is joined to two diagonal corners by welding,
The core of the boiling water reactor, wherein the thickness of the two clips is thinner than the thickness of the fuel channel box. In the core of the boiling water reactor according to claim 16,
A core of a boiling water reactor, wherein a width of a joint surface of the clip joined to an opening end portion of the fuel channel box is smaller than a plate thickness of the fuel channel box . In the core of the boiling water reactor according to claim 17,
The core of the boiling water reactor is characterized in that the shape of the clip joined to the fuel channel box is a substantially triangular shape imitating the shape of one corner of the fuel channel box. In the core of the boiling water reactor according to claim 17,
The clip joined to the fuel channel box has a substantially trapezoidal shape with a substantially triangular apex cut out, and two legs of the substantially trapezoidal clip are upper end portions of the fuel channel box. The core of a boiling water reactor characterized by being bonded to the core.

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