DE2054337A1 - Bracket for a control rod guide tube - Google Patents

Description

sue * (Zoeefuiecl / Cidi

PATENT ADVOCATE

November 4, 1970 Application files: 27 _O 9

PATENT APPLICATION Applicant; The Babcock & Wilcox Company, Corporation

161 East 42nd Street, New York, New York 10017, U ₀ S ₀ A.

¹¹ Bracket for a control rod guide tube "

The invention relates to a holder for control rod guide tubes in fuel assemblies for the core of nuclear reactors

In certain constructions of known fuel assemblies, guide tubes are provided together with the fuel rods, which as Channels are used for inserting and withdrawing the control rods, so far the guide tubes are so on the end grids of the fuel assembly that their replacement, which had become necessary due to pipe wear, was so difficult that even that for the connection the pipes with the grates used when removing the pipes were often unusable.

The invention is based on the object of the known shortcomings to eliminate a new design which allows easy replacement of the guide tubes without damaging any reactor parts perform.

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According to the invention, this object is achieved in a fuel assembly in that the guide roller for the control rods is detachable with the end grids be connected in such a way that they can be easily installed without disturbing the fuel rods already in the element

Numerous fuel rods are used in the fuel assembly of the present invention and at least one control rod guide tube held together at a certain parallel distance from one another by a pair of end grids, the ends of each guide tube being attached to the respective grids by releasable connections. The connecting device at one end of the pipe has a threaded bushing which is welded to the pipe and received in a passage through the corresponding grate will. The connection device for the other end of the pipe has a screw shaft that is welded to the pipe and in one Passage through the other grate is included; this passage is arranged concentrically to the grate passage, which the Bushing accommodates to the diameter of at least one of these grate passages is large enough to allow the guide tube to be attached to the bushing and shaft that are used to make the detachable Connections between the guide tube and the grates are used, can be passed in the longitudinal direction. These parts can thus be assembled and welded to the tube itself before that tube is built into the fuel assembly itself. As a result there is no need to carry out welding work in the narrow area of a fuel assembly.

The guide tube is held in relation to the grids by nuts, which are screwed onto the thread of the sleeve and the shaft

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In order to allow an axial displacement of the guide tube with respect to the grate connected to the shaft end of the tube, the passage through this grate is larger in diameter than the shaft and is provided with a thread the passage screwed to form the stem nut in an adjustable stop for. A similar axial displacement unit can optionally be provided at the other end of the guide tube; In this case, the pipe passage through the grate in question is larger in diameter than the socket and is provided with a thread .

The nuts of the bushing and of the shaft attached by tack welding, which can easily be removed by chiseling or grinding when making the connections wants to solve between pipe and grate.

The invention is shown in the drawing in an exemplary embodiment and described in more detail below. Show it:

Figure 1 is a side view, partially in section, of a fuel assembly,

Figure 2 is a cross-sectional view of the fuel assembly shown in Figure 1, taken along line 2-2.

FIG. 3 an enlargement of corner A according to FIG. 2,

FIG. 4 is a corner view of the installation of a typical control rod guide tube in the fuel assembly according to Figure 1,

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FIG. 5 shows an individual view similar to that according to FIG. 4, but with the modified guide tube installation arrangement _{or the like}

Figures 1, 2 and 3 show, in general, the Brennelementart 10, wherein the improved control rod guide tube mounting can be advantageously used according to the inventive idea ₀

In the fuel assembly 10 there are a plurality of longitudinally extending fuel rods 11 and guide tubes 12, which are at a certain parallel distance from each other by a pair of end grids (13 and 14 are held. In order to stabilize the rods 11 and the tubes 12, intermediate gratings 15 are arranged in an angular manner The tubes 12 are used to receive fuel rods (not shown) which are active during the operation of the reactor regulate the level of reactivity of the many fuel assemblies 10 that make up the core "

To accommodate the guide tubes 12 there is a pair for each tube 12 concentric passages provided by the grate 13 or 14. These Durohtritte can be formed in various ways as can be seen better from Figures 4 and 5

In the embodiment of the inventive concept shown in FIG the typical pipe passage 16 in the left grate 13 is a smoothly drilled hole, while the one shown in FIG Execution focft the passage 16A through grate 13 inside with a Thread is provided

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Both in FIG. 4 and in FIG. 5, the typical pipe passage in the right grate 14 is through the combination of an open one Part 18 of the grate 14, a ring 19 provided with an internal thread and attached to the grate 14 and a smoothly drilled ring 2o, which is also attached to the grate 14; the rings 19 and 20 are arranged concentrically.

The releasable connection of the pipe 12 with the grate 14 is made by parts causes which comprise a screw shaft 21 welded to the associated end of the tube 12, a threaded bushing 22 and a nut 23

In the embodiment according to FIG. 4, the releasable connection of the pipe 12 with the grate 13 is effected by parts that are attached to the associated End of the tube 12 include welded threaded bushing 24 and a nut 25

In the embodiment according to FIG. 5, the releasable connection of the pipe 12 with the grate 13 is achieved by the combination of one at the end of the pipe 12 welded threaded bushing 26, a threaded bushing 27 and a nut 28 causes.

In practice in which the idea of the invention is realized the bushings 24, 26 and the shafts 21 are welded to the tubes 12 before the same are installed in the fuel assembly 10., Accordingly the passage through at least one of the grids 13, 14 is large enough to allow the guide tube 12 together with shaft 21 and the bushing 24 or 26 welded to the pipe 12 is passed through in the longitudinal direction can be",

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So Mftrd ζ. B ₀ in the embodiment according to FIG. 4, the combination consisting of tube 12, the welded-on shaft 21 and the welded-on bushing 24 is passed in the longitudinal direction through the passage 16 in the grate 13 until the shaft 21 passes through the ring 19 and the ring 20 The outside diameter of the bushing 24 is approximately equal to the inside diameter of the passage 16 and equal to or larger than the outside diameter of the part of the shaft 21 passed through the grate 14. The bushing 22 is slipped over the shaft 21 and screwed through the ring 19 until it rests against the shoulder 30 of the shaft 21. The axial position of the tube 12 in relation to the grate 14 can be adjusted at will within the limits of the thread length of the bushing 22 by simply turn the bushing in the screw ring 19 · When the desired position is reached, the nut 23 is tightened until it is locked by the bushing 22, whereby the tube 12 is locked in its position · The connection between pipe 12 and grate 13 is completed by tightening nut 25 until it rests against grate 13. The connections to both grids can thus be released, while the connection to grate 14 is also adjustable in order to allow the pipe 12 to be moved lengthways between the grids 13 and 14 «

The installation of the prefabricated tube 12 with the combination consisting of the welded-on socket 26 and the shaft '21 in the arrangement according to FIG. 5, as far as the connection of the pipe 12 to the grate 14 is concerned, in the same way as has already been done in connection with Figure 4 was described «The difference between the arrangement according to Figure 4 and Figure 5 lies in the feature that in Figure S adjustable Connections to both grate 13 and grate 14 are provided.

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205433?

are seen. To get an adjustable connection to the grate 13, For example, the inner diameter of the threaded passage 16A is formed slightly larger than the outer diameter of the Shoulder 31 of sleeve 26. This allows the adjustment sleeve to be used 27, which serves to adjust the axial position of the pipe 12 in relation to the grate 13 «After the connection between pipe 12 and grate 14 is completed, the bushing 27 is accordingly pushed over the bushing 26 and screwed through the passage 16A, while the nut 28 is tightened until it is at the outer edge 32 the socket 27 rests and pulls the shoulder 31 to abut the inner edge 33 of the socket 27 and the axial position of the tube 12 in relation to be set on the grid 13 »

Tack welding W are expediently provided around the nuts 23, 25 and 28 to secure · If a tube 12 needs to be replaced, you can these tack welds W can be easily removed by grinding or chiselling in order to loosen the connections between the grids 13, 14 and to facilitate the tube 12 »

109824/1074

Claims (7)

PATENT CLAIMS t BBSKSBSeBBBBBSBnBBBnsSKBBSSSSBSSSBBSSSSSS ^ SBBasSSSS & assSSasSSSSS / 1, holder for a control rod guide tube (12) in a nuclear reactor fuel element (10), in which numerous fuel rods (11) and a control rod guide tube (12) at a certain distance from one another are held by a pair of grids (13, 14), which are marked that the holder is formed from a pair of concentric grate passages (16) each through a corresponding grate is, wherein a first conductive connection has a portion that connected to one end of the guide tube (12) and in one of the Grate passages is added to the end releasably (21, 22, 23J to connect to the grate (13), while the second detachable connection has a part which is connected to the other end of the guide tube (12) and in the other of the grate passages is added, with the hate of releasably connecting this end to the corresponding grate (14) 2. Holder according to claim 1, characterized in that that one of the grate openings has such a diameter, that the guide tube and the parts of the first and second connecting parts can be pushed through in the longitudinal direction when they are connected to the guide tube ends. 3. Holder according to claim 2, characterized in that that the part of the first connecting device is a threaded bushing (24) welded to the pipe end. 109824/1074 4. Holder according to claim 3, characterized gekennzeichne t f that the part of the second connecting device is a to the pipe end welded Schraibenschaft (21). 5. Holder according to claim 4, characterized in that that the first connecting device includes a nut (25) which engages the threads of the threaded bushing (24), and that the second connecting device includes a nut (23) which engages in the threads of the screw shaft (21) intervenes. 6. Holder according to claim 5, characterized in that that the second connecting device includes a threaded bushing which is disposed on the shaft to nit the nut located thereon and a threaded portion of the device to engage that the passage through the associated grate, said bushing, stem and nut cooperating to form the second connecting device to make adjustable, with the proviso that the axial position of the guide tube in relation to the second connecting device to change the associated grate optionally «. 7. Holder according to claim 5, characterized in that that the first connecting device includes a threaded sleeve which is arranged on the sleeve to "it the nut located thereon and a threaded portion of the device to engage that the passage through the associated grate, said bushing, bushing and nut cooperating to provide the first connection - 10 - 109824/1074 to make direction adjustable, with the proviso that the axial position of the guide tube in relation to the first connecting device to change the associated grate optionally. 109824/1074 tar side