JPH0347993B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an assembly jig for assembling an upper nozzle constituting the upper end of a fuel assembly used in a nuclear reactor.

[Prior Art] In general, a fuel assembly, as shown in FIG.
An upper nozzle 1 and a lower nozzle 2, a plurality of support grids 3 disposed between them at predetermined intervals, and a plurality of support grids 3 that are inserted into predetermined positions in the grid spaces of these support grids 3 and supported. A control rod guide tube 4 is fixed to the sleeve of the grid 3 and further connected to the upper and lower ends of the upper nozzle 1 and the lower nozzle 2, and the control rod guide tube 4 is inserted into the numerous grid spaces of the support grid 3 and supported. It is composed of a large number of fuel rods 5 supported by grids 3.

This fuel assembly is placed on the upper surface of the lower core plate 6 of the nuclear reactor, and the upper surface of the upper nozzle is connected to the upper core plate 7.
It is used while being fixed in the nuclear reactor by being pressed by the upper nozzle, and is elastically pressed against the lower core plate 6 by the upper nozzle.

Upper nozzle 1 used in the above fuel assembly
As shown in FIG. 7, there is a box-shaped upper nozzle cover 8 with one end open, a rectangular upper nozzle plate 9 that closes the opening of the upper nozzle cover 8, and a bottom surface of the upper nozzle cover 8. A plurality of sleeve extensions 10 are inserted through the sleeve extensions 8a and have their tips slidably fitted into the upper nozzle plate 9 in the axial direction and are irremovably engaged with the sleeve extensions 10. and a coil spring 12 disposed through a spring seat 11 between the upper nozzle plate 9 and the bottom plate 8a of the upper nozzle cover 8. By inserting the control rod guide tube 4 and expanding the diameter of both, the control rod guide tube 4...
is connected to.

Here, the upper nozzle plate 9 and each sleeve extension 10 are engaged with each other by the following structure. That is, the upper nozzle plate 9 has a plurality of through holes 13 formed therein. This through hole 13 includes a small diameter hole 13a formed at the lower end and a large diameter hole 1 formed at the upper end.
3b, and a bush 14 is disposed in the large diameter hole 13b so as to be slidable in the axial direction thereof. An engagement groove 1 is provided on the inner peripheral surface of the bush 14.
4a are formed along the circumferential direction. This bush 14 includes the sleeve extension 1.
0 is fitted, and a portion thereof corresponding to the engagement groove 14a is made to protrude outward in the radial direction. Based on this structure, the sleeve extension 10 and the bush 14 are connected, so that the sleeve extension 10 cannot be removed from the upper nozzle plate 9.

Further, a collar 15 is fixed to the intermediate portion of the sleeve extension 10 to prevent the sleeve extension 10 from moving toward the upper nozzle plate 9 with respect to the upper nozzle cover 8.

By the way, in order to assemble the upper nozzle 1 having the above configuration, the following procedure is performed.

First, insert the sleeve extension 10 into the upper nozzle cover 8 from the bottom surface 8a, and insert the spring seat 11 into the sleeve extension 10.
A coil spring 12 is disposed through the coil spring 12. On the other hand, bushes 14 are inserted into the large diameter holes 13b of the upper nozzle plate 9, respectively. Next, the tip of the sleeve extension 10 is inserted into the small diameter hole 13a of the upper nozzle plate 9, and in this state, the upper nozzle plate 9 is pushed into the upper nozzle cover 8 against the force of the coil springs 12. Then, adjust the position of the upper nozzle cover 8 so that the upper end of the predetermined sleeve extension 10 comes to the upper end of the bush 14, and in this state insert the tube expansion jig (not shown) into the large diameter hole 13b. As a result, the tip of the sleeve extension 10, which corresponds to the engagement groove 14a of the bush 14, is expanded. In this way, the tube is expanded one after another while adjusting the vertical position of the upper nozzle plate 9, and the upper nozzle plate 9 is assembled to the upper nozzle cover 8.

[Problems to be Solved by the Invention] In the above assembly work, the upper nozzle plate is pushed in and positioned vertically by hand, the positions of each sleeve extension and bushing are visually confirmed, and the upper nozzle plate is The tube is expanded sequentially while holding the plate in place. However, in manual work, it is difficult to support the upper nozzle plate against the force of the coil spring and hold it in a fixed position when expanding the tube with a tube expansion jig, so each sleeve extension must be The position relative to the button varies. As a result, the length of the sleeve extension protruding from the bottom plate of the upper nozzle cover varies, and the work of connecting the upper nozzle to the control rod guide tube, that is, inserting the control rod guide tube into the sleeve extension, There was a problem in that the efficiency of the linking work deteriorated.

In addition, in the manual operation described above, the tube must be expanded while checking the vertical position of the upper nozzle plate for each sleeve extension, which means that the tube can only be expanded in two locations at a time, which is extremely inefficient. There was a problem.

[Object of the Invention] The present invention has been made in view of the above circumstances, and eliminates variations in the vertical position of each sleeve extension with respect to the bush, and therefore simplifies the work of connecting the upper nozzle to the control rod guide tube. An object of the present invention is to provide an upper nozzle assembly jig for a fuel assembly that is efficient and can expand all sleeve extensions at once.

[Means for Solving the Problems] The upper nozzle assembly jig for a fuel assembly of the present invention includes a plurality of sleeve extensions provided through an upper nozzle cover of an upper nozzle for a fuel assembly, and an upper nozzle plate into which the sleeve extension is slidably fitted;
An assembly jig for engagingly connecting the sleeve extension at a predetermined position in the length direction, the assembly jig comprising a plurality of assembly jigs on which the upper nozzle cover is placed and through which one end of the sleeve extension is inserted. a support plate having a through hole formed therein; a frame to which the support plate is fixed; and a frame arranged to face the support plate and abut against the upper nozzle plate so as to direct the upper nozzle plate toward the upper nozzle cover. a pressing plate that is moved by pressing the pressing plate, and a drive mechanism that is provided between the pressing plate and the frame to move the pressing plate, and the pressing plate has each of the sleeve extensions expanded. A through hole is formed through which a processing jig for engaging the upper nozzle plate is inserted.

[Embodiment] FIGS. 1 to 5 are diagrams showing an embodiment of the present invention.

In these figures, reference numeral 16 indicates a pair of bases arranged on the left and right sides. A support plate 17 is fixed to the upper surface of these bases 16,16. Support plate 1
7 is a rectangular plate, and a hole 18 having a counterbored hole 18a is formed in the center thereof. A piston cylinder with a piston rod 19a facing upward is attached to this hole 18. A pusher 19b is attached to the tip of the piston rod 19a. Also,
Sixteen through holes 20 are formed in the support plate 17 so as to surround the hole 18, and a bush 21 is fitted into each through hole. This bush 21
The sleeve extension 10 is inserted and fixed therein. Further, a mounting plate 22 is attached to the upper surface of the support plate 17. Holes 23, 24 having the same diameter as the holes 18 and the through holes 20 of the mounting plate 22 have the same diameter.
is formed.

Further, pillars 25, 25 whose longitudinal directions are oriented upward and downward are fixed to the center portions of both sides of the support plate 17. Guide posts 26 are fixed to the upper ends of these pillars 25, with the longitudinal direction facing up and down. The upper end of this guide post 26 is formed into a tapered shape.

A guide block 27 is inserted into the guide post 26 so as to be slidable in the axial direction. This guide block 27 has a cylindrical shape, and a cylindrical guide bush 28 is fitted onto its inner peripheral surface. Both sides of a pressing plate 29 are fixed to the upper surface of the guide block 27. This pressing plate 2
9 is a rectangular main body 29 as shown in FIG.
a and protrusion parts 29b formed on both sides of the protrusion part 25, and the protrusion part 25 has a hole 3.
0 is formed. Further, in the portions of the pressing plate 29 facing the through holes 20 of the support plate 17,
Insertion holes (through holes) 31 are formed. The insertion hole 31 is for inserting a tube expansion jig when expanding the sleeve extension 10.

Furthermore, a stud bolt 32 with its longitudinal direction facing upward and downward is screwed onto the upper end of the guide post 26. A drive device (drive mechanism) 35 is attached to these stud bolts 32, 32 via a washer 33a and a nut 34a. The drive device 35 is formed by fixing plates 37, 37 and ribs 38, 38 to both sides of a piston cylinder 36. A disk-shaped pusher 36 is attached to the tip of the piston rod of the piston cylinder 36.
A is attached. The drive device 35 is
Its both ends are penetrated by stud bolts 32 and clamped by nuts 34a, 34b to prevent it from moving up and down. In addition, the code|symbol 33b in a figure is a washer.

The procedure for assembling the upper nozzle 1 using the upper nozzle assembly jig for fuel assembly having the above structure will be explained with reference to FIGS. 3 to 5. In addition,
Since the structure of the upper nozzle is the same as that described in the conventional example, the same reference numerals are given and the explanation thereof will be omitted.

First, the sleeve extensions 10 are inserted into the bushes 21 of the support plate 17 with the drive device 35 and the press plate 29 moved to the upper ends of the stud bolts 32 and guide posts 26. At this time, a guide plug 39 is attached to the upper end of each sleeve extension 10. Next, the upper nozzle cover 8 is placed on the mounting plate 2 with the sleeve extensions 10 inserted through the bottom plate 8a.
Place it on 2. Next, a spring seat 11 and a coil spring 12 are placed through each sleeve extension 10 . Next, the bush 1 of the upper nozzle plate 9
The guide plug 39 is inserted into the inside of the guide plug 39. In this state, the upper nozzle plate 9 is attached to the coil spring 1.
2 above the upper guide cover 8.

Next, as shown in FIG. 3, the pressing plate 29 is lowered until its lower surface contacts the upper surface of the upper nozzle plate 9. Similarly, the drive device 35 is lowered to lower the nut 34b and fixed so that the drive device 35 does not move upward. Next, the piston cylinder 36 is operated to push the pressing plate 29 downward. Then, the upper nozzle plate 9 descends against the force of the coil spring 12 and is inserted into the upper nozzle cover 8. Then, as shown in FIG. 4, when the upper nozzle plate 9 is lowered until the lower surface of the guide block 27 comes into contact with the upper end surface of the column 25, the nut 34a is lowered and the pressing plate 29 is fixed. In this state, the tips of the sleeve extensions 10 are inserted into the bush 14, and the heights of their upper end surfaces are the same.

Next, the drive device 35 is removed from the stud bolt 32 and the guide plug 39 is removed from the sleeve extension 10. Next, the tube expansion jig 40 is inserted into each insertion hole 31 of the press plate 29.

Here, the structure of the tube expansion jig 40 will be explained with reference to FIG. 5. In the figure, reference numeral 41 is a piston cylinder. A retracting portion 42a is provided at the tip of the piston rod 42 of the piston cylinder 41.
is formed. The retracting portion 42a has an outer diameter slightly smaller than the inner diameter of the sleeve extension 10, and a tapered tip.

A stopper 43 is disposed through the rear end of the piston rod 42. The dowel 43 has a cylindrical shape and is composed of a large diameter part 43a that fits into the large diameter hole 13b of the upper nozzle plate 9, and a small diameter part 43b that fits into the sleeve extension 10. . The piston rod 42 is adapted to be able to slide within this stop 43. Further, a cylindrical urethane ring 44 is disposed to penetrate between the stopper 43 and the retracting portion 42a.

The distal end of the sleeve extension 10 is expanded using the tube expansion jig 41 having the above configuration.

First, the retractable portion 42a of the piston rod 42 is inserted into the sleeve extension 10. Next, move the piston rod 42 to the arrow A in FIG.
move in the direction. Then, the urethane ring 44
is compressed in the longitudinal direction by the retracting portion 42a and the stopper 43, and tends to expand outward in the radial direction.
As a result, the portion of the sleeve extension 10 corresponding to the engagement groove 14a of the bush 14 is pushed apart, and the bush 14 and the sleeve extension 10 are connected.

Next, the piston rod 42 is moved in the direction of arrow B. Then, the shape of the urethane ring 44 returns to its original cylindrical shape. Then, the tube expansion jig 40 is removed from the sleeve extension 10.

Next, the press plate 29 is moved upward, and the support plate 1
The piston cylinder 19 of No. 7 is operated to move the assembled upper nozzle 1 upward and take it out.

According to the above-described upper nozzle assembly jig for a fuel assembly, the upper nozzle plate 9 can be pushed into the upper nozzle cover 8 while being held in a horizontal state by the pressing plate 29. The position of sleeve extension 10 relative to 14 can be constant. In addition, the pipe expansion work can be performed at 16 locations at once by inserting the pipe expansion jig 41 through each through hole 31 of the press plate 29 while maintaining the above state, so that the assembly work of the upper nozzle can be performed easily. It can be done efficiently.

In the above embodiment, the drive device 35 is provided above the press plate 29, and is removed from the stud bolt 32 during pipe expansion work.
The configuration is not limited to this, but for example, a piston cylinder that presses down both sides of the pressing plate 29 separately may be attached to the stud bolt,
If the upper surface of the press plate 29 is configured to be open, there is no need to remove the piston cylinder during pipe expansion work, and the assembly work of the upper nozzle can be performed more efficiently.

[Effects of the Invention] As explained above, the fuel assembly upper nozzle assembly jig of the present invention includes a plurality of sleeve extensions provided through the upper nozzle cover of the fuel assembly upper nozzle, and these sleeve extensions. An assembly jig for engagingly connecting an upper nozzle plate to which a sleeve extension is slidably fitted at a predetermined position in the length direction of the sleeve extension, wherein the upper nozzle cover is a support plate on which a plurality of through holes are formed through which one end of the sleeve extension is inserted; a frame to which the support plate is fixed; a press plate that is brought into contact with the upper nozzle plate and presses and moves the upper nozzle plate toward the upper nozzle cover; a drive mechanism that is provided between the press plate and the frame and that moves the press plate; The press plate is characterized in that a through hole is formed in the press plate, into which a processing jig for expanding each sleeve extension and engaging it with the upper nozzle plate is inserted. , there is no variation in the vertical position of each sleeve extension with respect to the upper nozzle plate,
Therefore, the work of connecting the upper nozzle to the control rod guide tube can be performed efficiently, and the through-hole formed in the pressing plate can be connected while maintaining the posture of the upper nozzle cover and the upper nozzle plate. Since all the sleeve extensions can be expanded at once by inserting a processing jig from the top, it is possible to assemble the upper nozzle efficiently and reliably.

[Brief explanation of drawings]

1 to 5 are views showing one embodiment of the present invention, in which FIG. 1 is a fragmented sectional view showing an upper nozzle assembly jig for a fuel assembly, and FIG.
Fig. 3 is a fragmented sectional view showing the state in which the upper nozzle is set in the upper nozzle assembly jig for a fuel assembly, and Fig. 4 is a view from the state shown in Fig. 3 in which the upper nozzle plate is inserted into the upper nozzle cover. FIG. 5 is a fragmented sectional view showing a pushed-in state, FIG. 5 is a fragmented sectional view showing the tube expansion jig, FIG. 6 is a front view showing the fuel assembly, and FIG. 7 is a fragmented sectional view showing the upper nozzle. 17... Support plate, 24... Through hole, 29... Pressing plate, 31... Insertion hole (through hole), 35... Drive device (drive mechanism).

Claims (1)

[Claims] 1. A plurality of sleeve extensions provided through the upper nozzle cover of the upper nozzle for a fuel assembly, and an upper nozzle plate into which these sleeve extensions are slidably fitted,
An assembly jig for engagingly connecting the sleeve extension at a predetermined position in the length direction, the assembly jig comprising a plurality of assembly jigs on which the upper nozzle cover is placed and through which one end of the sleeve extension is inserted. a support plate in which a through hole is formed; a frame to which the support plate is fixed; and a frame arranged to face the support plate and in contact with the upper nozzle plate, and to connect the upper nozzle plate to the upper nozzle cover. It consists of a press plate that presses and moves the press plate toward the target, and a drive mechanism that is provided between the press plate and the frame to move the press plate, and the press plate has each of the sleeve extensions expanded. 1. An upper nozzle assembly jig for a fuel assembly, characterized in that a through hole is formed through which a processing jig is inserted to engage the upper nozzle plate.