JPH057595Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Purpose of the Invention] (Field of Industrial Application) The present invention relates to a nuclear fuel spacer welding device, and particularly to a restraining and supporting device for a cylindrical member to be welded, etc. of the above-mentioned nuclear fuel spacer.

(Problems to be solved by conventional techniques and ideas) Generally, in a nuclear fuel assembly, spacers are provided to hold a large number of fuel rods arranged parallel to each other in a predetermined position at a predetermined interval. .

5 and 6 are a plan view and a partially longitudinal side view of the spacer, in which a predetermined number of cylindrical members 1 having an inner diameter through which the fuel rods can be inserted are arranged vertically and horizontally so that their axes are parallel to each other. A side band 2 constituting an outer frame is attached to the outer periphery of the fuel rods, and the fuel rods inserted into the inner cylindrical member 1 are supported by a spring member 3 provided on the cylindrical member 1. By pressing against a protrusion 4 formed on the inner surface of the cylindrical member, the fuel rod is prevented from moving in the radial direction. Note that the reference numeral 5 in FIG. 5 is a central opening.

By the way, when welding the above-mentioned cylindrical members, the above-mentioned cylindrical members are arranged and arranged in a predetermined number vertically and horizontally, fixed from four directions on the outside, and each position of the contacting part of the cylindrical members is irradiated with a laser beam or a non-consumable tungsten electrode. Welding is done in However, in this case, it is difficult to align the welding position due to the finish of the outer diameter of the cylindrical member, which not only causes welding defects such as burn-through, but also makes it extremely difficult to maintain the accuracy of the center position of each cylindrical member through which the fuel rod is inserted. There were some problems, such as difficulty. Furthermore, it is difficult to maintain the outer diameter of the welded finished product due to welding distortion and thermal shrinkage during welding, as described above, and this is a major factor in reducing manufacturing yield.

In view of these points, the present invention aims to provide a nuclear fuel spacer welding device that can maintain sufficient center position accuracy between cylindrical members to be welded, and can restrain and correct welding distortion and thermal contraction during welding. purpose.

[Structure of the idea]

(Means for Solving the Problems) The present invention provides a means for circumscribing at two or more points on the outer circumferential surface of the cylindrical members to be welded arranged at equal intervals vertically and horizontally to form each cell of a nuclear fuel spacer. A plurality of support pins for restraining the cylindrical member are erected, a spacer holding jig is provided to be installed in the welding chamber, and the spacer is welded to the outer periphery of the cylindrical member to be welded arranged at equal intervals vertically and horizontally. The present invention is characterized by being provided with a pressing mechanism capable of adjusting external pressure, which presses a plate-shaped side band constituting the outer frame toward the cylindrical member to be welded.

(Function) When each cylindrical member to be welded is arranged and placed at a predetermined position on the spacer holding jig, two or more points on the outer peripheral surface of the cylindrical member to be welded are circumscribed by the support pins set up from the spacer holding jig. and is held in place. Therefore, the accuracy of the center position of the welded member is guaranteed, the welding position can be easily set, and welding defects such as burn-through are prevented from occurring. Also,
By press-welding the side band to the outer peripheral portion of the cylindrical member to be welded held at the predetermined position using the pressing mechanism, the outer diameter dimension of the welded finished product can be easily maintained.

(Embodiment) Hereinafter, an embodiment of the present invention will be described with reference to FIGS. 1 to 4.

In FIGS. 1 and 2, reference numeral 10 denotes a spacer holding jig that is placed and fixed on the base 11 of the welding chamber.
The plurality of positioning holes 12 drilled in the base 1
It is positioned by inserting it into a positioning pin 13 implanted in the base plate 1, and is fixed to the base plate 11 by a fixture 14. By the way, on the upper surface of the spacer holding jig 10, a predetermined number of cells, for example 8×
Eight cylindrical members 15 are arranged and placed so that their side walls are adjacent to each other vertically and horizontally, and the spacer holding jig 10 has a central opening formed in the center of the spacer. A central support pin 16 having an outer diameter equal to the diameter of the central opening is erected corresponding to the central opening. In addition, the spacer holding jig 10 is provided with the four cylinders at points located in each central space formed by the four adjacent cylinder members 15 of the cylinder members arranged as described above. Support pins 17 circumscribing the outer peripheral surface of the member 15 are arranged and erected at equal intervals vertically and horizontally.

Furthermore, a pressing mechanism is disposed on the outer periphery 4 side surface of the spacer holding jig 10 to press the side bands 18 that surround the cylindrical members 15 arranged vertically and horizontally from the outside toward the cylindrical members. There is. That is, at the upper part of each side of the spacer holding jig 10, moving members 19 are disposed which move toward or away from the spacer holding jig 10 in the horizontal direction by driving devices (not shown). ,
Each moving member 19 has a plurality of pressing pins 2 each biased in the projecting direction by a spring 20.
1 is installed. By the way, the above press pin 2
1, the pressing pin 21a that comes into contact with the flat plate-shaped portion of the side band 18 has a rod shape, and the pressing pin 21b that presses the corner of the side band 18 has a bent portion at its tip that is bent diagonally outward. has been done.

On the other hand, the spacer holding jig 10 includes each cylindrical member 1 placed on the spacer holding jig 10.
5 to be welded together, the joint between the cylindrical member 15 and the side band 18, and the connecting member 22 that connects the innermost cylindrical member 15 to each other.
Enveloped gas inlet ports 23, 24, and 25, which penetrate vertically, are provided below the joint with the capacitor. Further, a recess 27 is provided on the bottom surface of the spacer holding jig 10 so as to form an appropriate gap 26 between the spacer holding jig 10 and the base 11. is communicated with.

Therefore, when assembling and welding the spacer, the cylindrical member 15 to be welded is placed on the spacer holding jig 10 set at a predetermined position so that the support pin 17 is positioned in the center space of the four adjacent cylindrical members. After arranging the cylindrical members vertically and horizontally and abutting the side bands 18 on the outer periphery of the aligned cylindrical members, each movable member 19 of the pressing mechanism is moved to the cylindrical member side, and the pressing pins 21a and 21b are aligned. Therefore, the nuclear fuel spacer is pressed in an adjustable manner to restrain the nuclear fuel spacer in an appropriate state.

Therefore, the welding chamber is sealed, and the inside of the welding chamber is evacuated through the vacuum exhaust port 28 and the encapsulated gas introduction ports 23, 24, and 25. After that, when the inside of the welding chamber reaches a predetermined degree of vacuum (not shown), By switching the valves, an inert gas is introduced into the welding chamber through the vacuum exhaust port 28 and the encapsulated gas introduction ports 23, 24, and 25, and the inside of the welding chamber is replaced with the inert gas. When the inside of the welding chamber has been replaced with inert gas in this way, each joining surface of the cylindrical member 15 to be welded, the cylindrical member 15 Welding is performed on the joint surfaces between the side band 18 and the side band 18, and the joint surface between the cylindrical member 15 and the connecting member 22. On the other hand, during this welding, inert gas is constantly introduced from each envelope gas inlet 23, 24, 25, and the welded portion is shielded and cooled by the flow of this inert gas.

After welding, after the pressing pin 21 in the pressing mechanism is retreated, the nuclear fuel spacer, which is firmly restrained by heat contraction, is pushed up by a take-out pin that is moved upward by an air cylinder (not shown), and the spacer holding jig is removed. Remove from ingredients.

In addition, in the above embodiment, the pressing pin 21a is rod-shaped, but FIGS. 3a and 3b
As shown in the figure, the tip may be bifurcated or trifurcated vertically, and the side band may be pressed at multiple locations above and below. Also, at the tip of the pressing pin 21b,
As shown in FIGS. 4a, b, and c, a pressing portion expanding at an obtuse angle, a pressing portion bent at a right angle, or an arc-shaped pressing portion may be formed.

[Effect of idea]

Since the present invention is constructed as described above, each cylindrical member to be welded is circumscribed by at least two or more support pins and restrained in a predetermined position, so that the cylindrical member is maintained at an appropriate pitch. Moreover, when the pressing mechanism presses the cylindrical member from the periphery toward the center via the side band, the support pin acts to restrain and straighten the cylindrical member, making it possible to maintain the outer diameter of the welded finished product. It is easy to weld, and nuclear fuel spacers can be welded efficiently.
Further, welding defects can be prevented and welding quality can be improved without being affected by the finish of the outer diameter of the cylindrical member.

[Brief explanation of drawings]

Fig. 1 is a plan view of the spacer holding jig of the nuclear fuel spacer welding device of the present invention, Fig. 2 is a longitudinal cross-sectional view of the same, Fig. 3 a, b, and Fig. 4 a, b, c are of the press pins, respectively. FIG. 5 is a plan view of a nuclear fuel spacer, and FIG. 6 is a partially sectional side view of the nuclear fuel spacer. 10...Spacer holding jig, 11...Base, 1
5...Cylindrical member, 16...Central support pin, 17...
...Support pin, 18...Side band, 21a, 2
1b...Press pin, 23, 24, 25... Encapsulated gas inlet.

Claims (1)

[Claims for Utility Model Registration] 1. A plurality of cylindrical members circumscribed at two or more points on the outer circumferential surface of a cylindrical member to be welded arranged at equal intervals vertically and horizontally to form each cell of a nuclear fuel spacer and restraining the cylindrical member to be welded. In addition to erecting support pins,
A spacer holding jig that is installed in the welding chamber, and a plate-shaped side band that is welded to the outer periphery of the cylindrical members to be welded and arranged at equal intervals vertically and horizontally to form an outer frame are placed on the side of the cylindrical members to be welded. A nuclear fuel spacer welding device characterized by having a pressing mechanism capable of adjusting external pressure. 2. Utility model registration claim No. 2, characterized in that a center support pin is attached to the center of the spacer holding jig for maintaining the true position and dimensions of the opening in the center of the nuclear fuel rod spacer. 1
The nuclear fuel spacer welding device described in Section 1.