JPH0218679B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a welding device using laser light for nuclear fuel spacers for fuel assemblies.

[Technical background of the invention and its problems]

Generally, in a fuel assembly for a nuclear reactor, nuclear fuel spacers are provided at multiple locations in the longitudinal direction to correct curvature of the nuclear fuel rods and to suppress vibrations of the fuel rods caused by the flow of coolant.

That is, FIG. 1 is a longitudinal cross-sectional view of the fuel assembly for the above-mentioned nuclear reactor, and in the fuel channel 1, there are
A plurality of fuel rods 4 and water rods 5 are installed in an array, with their upper and lower ends supported by an upper tie plate 2 and a lower tie plate 3, respectively. A plurality of spacers 6 are provided in the axial direction of the fuel rods 4 for restraining vibration and ensuring a coolant flow path.

The spacer 6 has a square band 7 as shown in FIG. 2 and FIG. small partitions 12 are formed. Further, a lantern spring 13 having a leaf spring portion 13a projecting outwardly on each side is attached to each intersection of the bars 8 and 9, and a fuel rod inserted into each of the small partitions 12 is attached to the lantern spring 13. 4 from the corner of the small partition 12 to the S bends 10a, 1 formed on the dividers 10, 11.
It is arranged to come into elastic pressure contact with 1a.

By the way, when manufacturing the above-mentioned spacer, the bar 8 and the bar 9, the bars 8, 9 and the divider 10,
11. The band 7 and the dividers 10, 11, the connecting portion of the bands, and the welding points between the band 7 and the bars 8, 9 are welded by spot welding. That is, gas tungsten arc welding is generally employed for these weldings, and tungsten electrodes are provided for the number of welding points, and the required welding parts are automatically and sequentially welded.

However, since the number of welding points in the spacer is very large, the consumption of electrodes is large, and it takes a lot of time to replace the electrodes and polish the electrodes, and the production efficiency is not very good. Furthermore, in order to obtain high welding strength in the gas tungsten arc method, a certain amount of heat input is required. However, as the amount of heat input increases, welding defects are more likely to occur, thermal deformation occurs, and highly accurate dimensions cannot be maintained.
Particularly, there is also the problem that burn-through occurs frequently in areas where the heat capacity of the component is small.

[Purpose of the invention]

In view of these points, an object of the present invention is to provide a welding device for nuclear fuel spacers that can improve production efficiency in welding fuel spacers, eliminate welding defects, and improve quality. do.

[Summary of the invention]

The present invention provides movable boxes movable in the X-axis and Y-axis directions within each plane on each side and on both upper and lower surfaces of a frame body that allows nuclear fuel spacers for fuel assemblies to be placed in the center. At the same time,
Attach a laser output unit to each movable box,
Each laser output unit is connected to a laser beam source via a fiber, and the spacer components are welded simultaneously at the welding points on each surface using laser light. .

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIGS. 4 and 5.

4 and 5, reference numeral 20 denotes a frame body of the present welding apparatus in which a nuclear fuel spacer 6 can be disposed in the center by appropriate means, and each of the frame bodies 20 Vertical shafts 21 that can move in the left and right directions are attached to the sides, and movable boxes 22 that can move in the vertical direction are attached to the vertical shafts 21, respectively.
a, 22b, 22c, and 22d are attached.

On the other hand, horizontal shafts 23 that are movable in the front and back directions are attached to both the upper and lower surfaces of the frame 20, and movable boxes 24a and 24b that can be moved in the left and right directions along the horizontal shafts 23 are attached to the horizontal shafts 23. are installed on each. That is, each side surface and both upper and lower surfaces of the frame body 20 are provided with movable boxes that can move in the X-axis and Y-axis directions within each plane.

Each of the movable boxes 22a, 22b, 22c,
Laser output units 25a, 25b, 25c, 25d and 26a, 26b are attached to 22d, 24a, and 24b, respectively.
5d, 26a, 26b are fibers 27, respectively.
Beam entrance units 29a, 29b, 29c, 29d, provided in the beam splitter 28 via a, 27b, 27c, 27d, 27e, 27f,
It is connected to 29e and 29f. The beam splitter 28 includes laser beams 30a and 30.
b is supplied from a laser source (not shown), and the laser beam 30a is split into four through a reflecting mirror provided in the beam splitter 28, and the split laser beam becomes a beam. Inlet units 29a, 29b, 29c, and 24d
Further, the laser beam 30b is split into two by a reflecting mirror and supplied to beam entrance units 29e and 29f.

Therefore, when welding each part of the nuclear fuel spacer 6, the nuclear fuel spacer 6 is placed in the center of the frame 20 by appropriate means, and each movable box 2 is welded.
2a, 22b, 22c, 22d, 24a, 24b
are located at positions corresponding to the first welding points on each surface, respectively, and supply laser beams 30a, 30b to the beam splitter 28. When the laser beams 30a, 30b are supplied to the laser output units 25a, 25b, 25, respectively,
The beams are incident on each welding point from c, 25d and 26a, 26b, and welding of the welding points is performed simultaneously.

Therefore, each movable box 22a, 22b, 22
c, 22d, 24a, and 24b are moved to positions corresponding to the second welding points on each surface, and those welding points are welded in the same manner, and each welding point can be sequentially welded thereafter.

Incidentally, in the above embodiment, the connections on each side were performed simultaneously, but these connections may be performed sequentially. Moreover, any number and division method of fibers can be adopted as the number of fibers and the division method of the laser beam.

〔Effect of the invention〕

Since the present invention is configured as described above, it is only necessary to provide at least one laser output unit for each surface of the spacer, so the configuration of the welding device can be made extremely simple.
Moreover, the problems related to electrodes as mentioned above can be solved without using welding electrodes, and since laser welding, which is high-density energy welding, is used,
Welding defects and thermal deformation caused by gas tungsten arc welding can also be reliably prevented.

[Brief explanation of drawings]

Figure 1 is a longitudinal side view of the nuclear fuel assembly, Figure 2 is an enlarged plan view of the spacer, and Figure 3 is the same as in Figure 2.
4 is a plan view of the welding apparatus of the present invention, and FIG. 5 is a side view of the same. 4... Fuel rod, 6... Spacer, 20... Frame, 22
a, 22b, 22c, 22d, 24a, 24b...
Movable box, 25a, 25b, 25c, 25
d, 26a, 26b...Laser output unit, 27
a, 27b, 27c, 27d, 27e, 27f...
Fiber, 28...beam splitter.

Claims (1)

[Scope of Claims] 1. Movable boxes movable in the X-axis and Y-axis directions within each plane are provided on each side and both upper and lower surfaces of a frame body in which a nuclear fuel spacer for a fuel assembly can be disposed in the center. 1. A nuclear fuel spacer welding device characterized in that a laser output unit is attached to each movable box, and each laser output unit is connected to a laser beam source via a fiber. 2. The nuclear fuel spacer welding apparatus according to claim 1, wherein the laser beam is split into a plurality of parts by a beam splitter, and each of the split beams is sent to each laser output unit.