KR100906401B1 - Easy Release and Coupling Joint Between Guide Tube And Upper-End-Fitting Which Has an Inner-Extension with Locking Device - Google Patents

Abstract

The present invention relates to the connection between the upper stationary body and the guide tube of the nuclear fuel assembly, and more particularly, to a fastening method between the inner insertion tube and the flow path plate and the guide tube forming the upper stationary body.

Specifically, the inner insert tube body is rotated when the upper head is disassembled from the inner insert tube body by disassembling the upper head from the insert tube body as a means of easily separating the upper fixation body of the fuel assembly from the guide tube. It is characterized in that the guide tube and the inner insertion tube body to maintain the fastening state.

Nuclear fuel assembly, guide tube, top fixture, internal insertion tube, fastening, anti-rotation

Description

Easy Release and Coupling Joint Between Guide Tube And Upper-End-Fitting Which Has an Inner-Extension with Locking Device}

The present invention relates to the fastening of the upper stationary body and the guide tube of the nuclear fuel assembly, and more particularly to the fastening structure of the upper stationary body and the guide tube for preventing the rotation of the inner insertion tube generated when the upper stationary body is separated. .

A nuclear reactor is a device made to be used for various purposes such as generating heat by artificially controlling the fission reaction of fissile material, producing radioisotopes and plutonium, or forming a radiation field.

In general, light water reactors use enriched uranium with an increased ratio of uranium-235 to 2-5%. In order to process the nuclear fuel used in nuclear reactors, uranium is molded into cylindrical pellets weighing about 5g. These pellets are charged into a Zircaloy cladding tube under vacuum, a spring and helium gas are placed therein, and the upper rod stopper is welded to make fuel rods. The fuel rods finally form a nuclear fuel assembly and are burned through a nuclear reaction in the reactor.

The general shape of the nuclear fuel assembly is shown in FIG. 1.

Referring to FIG. 1, the nuclear fuel assembly includes a skeleton composed of an upper fixing body 4, a lower fixing body 5, a support lattice 2, a guide tube 3, and a measuring tube 6. It is composed of a fuel rod 1 charged in the support grid 2 and supported by a spring (not shown) and a dimple (not shown) formed in the support grid 2. When assembling the assembly, to prevent scratches on the surface of the fuel rod (1) and to prevent damage to the spring in the support grid, apply a locker to the surface of the fuel rod, insert it into the skeletal body, and then attach and fix the upper and lower fixtures to fix the fuel assembly. After the assembly is completed, the assembly manufacturing process is completed by removing the locker of the completed assembly, and then inspecting the fuel rod gap, twisting, electrical length, and dimensions.

As shown in FIG. 2, the upper fixing body 4 is composed of a pressing plate 42, a pressing spring 43, an inner insertion pipe 45, an outer guide pillar 44, and a flow path plate 41. have.

Referring to [FIG. 1] and [FIG. 2], the inner insertion tube 45 of the upper fixing body 4 is connected to the guide tube 3 and is configured to firmly fix the nuclear fuel assembly in the reactor. It also ensures the structural stability of the fuel even during combustion.

Meanwhile, the upper fixing body and the guide tube are connected to be disassembled and reassembled. This is to disassemble the upper fixing body to secure a path for extracting the fuel rods. The dismantling of the top fixtures carried out in the reservoir should be done by the operator from a distance to prevent the radiation damage as much as possible. Therefore, it is necessary to design the fastening structure of the upper fixture and the guide tube in a structure that can be disassembled and assembled at a long distance.

In general, the connection method of the guide tube and the upper fixing body used is shown in [FIG. 2] and [FIG. 3]. The fastening method of the guide tube 3 and the upper fixing body 4 is to process the male screw on the lower end 451 of the inner insertion tube 45 as shown in Figure 2 and guide tube as shown in Figure 3 The upper fixing body 4 and the guide tube 3 are connected by machining the female screw into the inside of the screw part 31 and combining the guide tube and the inner insertion tube by the screw fastening method. A male thread is machined in the lower portion of the outer guide pillar 44, and the screw end of the outer guide pillar 44 and the passage plate 41 are locally welded after the fastening of the flow guide plate 44 with the outer guide pillar 44. Prevents the rotation of In addition, in order to prevent loosening of the inner insertion tube 45, the head portion of the inner insertion tube 45 is radially pressed in contact with the outer guide pillar 44, and the head portion is contacted to the head portion by a specific force or more. Torque was applied to disassemble it.

However, when the separation is made by rotating the inner insertion tube 45 of the upper fixing body in this state, the distance between the outer surface of the inner insertion tube 45 and the inner surface of the outer guide pillar 44 is very close. If the concentricity is not matched or foreign matter is inserted and fixed between the surface and the surface becomes difficult to rotate the screw. That is, due to frictional heat generated by the contact surface, the inner insertion pipe 45 and the outer guide pillar 44 made of stainless steel are welded to each other by the effect of cold welding, so that the screw is impossible to loosen.

Therefore, as an invention to solve the above problems, US Patent No. 4702883 `` Reconstitutable fuel assembly having removable upper stops on guide thimbles '' and US Patent No. 4687630 `` Top nozzle and guide thimble joint structure in a nuclear fuel assembly '' There is this.

The present invention was intended to minimize the contact surface at the time of separation by separating the head of the outer guide column without the inner insertion tube, the screw processing the separated upper head.

And when the guide tube is fastened with the guide tube screw portion and the screw in the lower portion of the outer guide pillar there are two screw fastening on the upper and lower portion of the outer guide pillar.

Therefore, in order to disassemble the upper fixing body by rotating the upper head screw of the outer guide pillar, the outer guide is fastened to the lower part of the outer guide pillar because the upper head of the outer guide pillar and the outer guide pillar is screwed There is a problem that the screw coupling of the pillar and the guide tube can be loosened.

Therefore, a separate wedge device is provided on the outer guide column so that the screw of the lower portion of the outer guide column is not loosened by rotation, but there is a problem in that the assembly and separation process is cumbersome.

The present invention provides a means for screwing the inner insertion tube upper head into the inner insertion tube body, and the inner insertion tube body is not separated from the guide tube when the upper insertion head is removed to remove the upper fixture. .

A guide tube for supporting the support grid of the fuel assembly;

A flow path plate positioned at an upper portion of the guide tube and having a fastening hole formed therein, an outer guide column fastened to the fastening hole of the flow path plate by a lower end portion, and a lower end inserted into the outer guide column to fasten the through hole of the flow path plate; Including a top fixing body consisting of an inner insertion pipe penetrating through and an inner insertion pipe head coupled to the upper end of the inner insertion pipe and the outer guide pillar to interconnect the inner insertion pipe and the outer guide pillar,

Rotation of the inner insertion tube body when the inner insertion tube head is rotated at any one or more of the connection portion between the connection hole of the inner insertion tube and the flow path plate, the upper portion of the inner insertion tube head, the inner insertion tube body, and the outer guide pillar. As the problem solving means is provided with a rotation preventing means for preventing the.

When the anti-rotation surface is formed on the inner insertion tube of the upper fixing body and the anti-rotation locking jaw is formed on the flow path plate to separate the integrated upper fixing body, there is an effect of preventing the loosening of the inner insertion tube and the guide tube caused by the rotation. It is not necessary to provide a member for preventing rotation separately, and the contact surface of the rotating part is minimized, so that the assembly and disassembly of the upper fixing body is easy, thereby reducing the time.

The present invention is to implement the above object,

The present invention is characterized by the outer guide pillar 120, the inner insertion pipe 150, the flow path plate 160, the guide pipe (3).

(Therefore, the pressing plate and the pressing spring, which are components of the upper fixing body not related to the present invention, will not be described.)

The following relates to a specific coupling structure of each component shown in Figure 4 coupled to.

Referring to Figure 5,

Outer guide pillar 120 is a hollow cylindrical shape, the top and bottom is open, the screw 102 is formed for fastening with the flow path plate 160 from the bottom of the outer surface to a specific height.

From the upper end of the outer guide pillar 120 to a predetermined position downward is a shape larger in diameter than other portions of the outer guide pillar 120. It is possible to fasten with the pressing plate (not shown) by the locking jaw 104 caused by the diameter difference.

As shown in FIG. 6,

The internal insertion pipe 150 is composed of an internal insertion pipe body 130 and an internal insertion pipe upper head 140.

The inner insertion pipe main body 130 has a hollow cylindrical shape, and the upper and lower surfaces thereof are opened as in the outer guide pillar 120, and have a shape longer than the outer guide pillar 120 in the inner space of the outer guide pillar 120. The upper part is inserted and the height is the same as the outer guide pillar 120, the lower portion is protruded longer than the outer guide pillar 120.

The lower portion of the inner insertion tube body 130, that is, the portion protruding out of the outer guide pillar 120 is formed with a screw 132 to a predetermined height, which is used when combined with the guide tube (3) to be described later.

The inner insertion pipe upper head 140 is fastened to the upper end of the inner insertion pipe main body 130, the upper and lower parts are the same shape, but the shape of the cork stopper having a different diameter is opened and penetrated through And, a predetermined portion of the inner surface of the lower screw 142 is formed, and the screw is coupled to the outer surface of the inner insertion tube body upper portion 134.

The inner insertion pipe upper head 140 has the outer diameter of the outer guide column 120 such that the maximum diameter of the locking step 144 generated by the diameter difference of the upper and lower portions is equal to or larger than the upper diameter of the outer guide column 120. It is a shape that can be caught without penetrating into it. In addition, the thin film structure of the upper head is crimped into the groove of the outer guide pillar to prevent loosening of the screw.

In addition, a rotation preventing surface 136 is formed below the inner insertion tube body 130.

The anti-rotation surface 136 is located above the screw located in the lower portion of the inner insertion tube body 130, a portion is cut in the shape of a circular flange is formed with a flat surface. This serves to prevent the occurrence of the internal insertion tube body 130 rotation when separating the internal insertion tube upper head 140 and the internal insertion tube body 130.

As shown in FIG. 7, a specific portion of the flow path plate 160 is provided with a fastening through-hole 162 for fastening the outer guide pillar 120 and the inner insertion pipe 150.

Inside the fastening through-hole 162, the stepped portion is formed along the circumference, and the diameter of the stepped diameter is the same as the outer diameter of the outer guide pillar 120, and the circular shape formed in the above-described inner insertion tube body 130. The upper surface of the flange and the lower surface of the step are in contact with each other.

The upper portion of the fastening through-hole is the same as the outer diameter of the outer guide pillar 120 and is in the shape of a screw, the screw is formed with the lower portion of the outer guide pillar 120 described above.

On the contrary, there is an anti-rotation catching jaw 166 at the bottom of the fastening hole. The anti-rotation catching jaw 166 is a place where the anti-rotation surface 136 of the aforementioned internal insertion tube body 130 is located, and has a polygonal shape corresponding to the anti-rotation surface.

The guide tube screw portion 31 is formed on the upper end of the guide tube 3 (see [Fig. 3]), the guide tube screw portion 31 is open in the cylindrical shape of the hollow, the inner insertion pipe 150 The same size as the lower diameter of the), the inner surface of the guide tube screw portion 31 is formed with a screw.

As such, the inner insertion tube body 130 and the lower portion of the guide tube screw portion 31 are fastened by screwing.

Looking at the process of dismantling the combination of the upper stationary body and the guide tube made of the same configuration with reference to Figure 6,

First, the inner insertion tube upper head 140 is rotated and separated from the inner insertion tube body 130. In addition, the integrated top fixing body composed of the outer guide pillar 120, the flow path plate 160, the pressing spring (not shown), and the pressing plate (not shown) is separated from the fuel assembly.

When dismantling the inner insertion tube upper head 140 and the inner insertion tube body 130 in the disassembly process, the screw coupling of the inner insertion tube body 130 and the guide tube screw portion 31 may be loosened. However, the inner insertion pipe main body 130 and the guide tube screw part unintentionally by the anti-rotation surface 136 formed on the inner insertion pipe body 130 and the anti-rotation locking jaw 166 formed on the flow path plate 160 ( 31) to prevent separation.

8 and 10 illustrate one embodiment 1 and 2 related to the anti-rotation surface of the inner insertion tube body and the anti-rotation jaw of the flow path plate.

Unlike the inner insertion tube body 130 described above, it can be used as a plurality of anti-rotation surfaces 135 by forming several flat surfaces.

In more detail, as shown in Figure 8, the anti-rotation surface 135 formed at intervals of 90 ° is formed on the circular flange of the inner insertion tube body 130, each of the anti-rotation surface amount The incision plane part 133 is formed in the side.

The nuclear fuel incision plane 133 between the anti-rotation surfaces of the nuclear fuel assembly is arranged so as not to be caught in the circular flange of the inner tube body when charging or withdrawing the nuclear fuel rod positioned adjacent to the guide tube in the support grid of the fuel assembly. will be.

In addition, as another embodiment 2 with respect to the internal insertion tube body 130,

As shown in FIG. 9, the anti-rotation surface 138 formed at a 90 ° interval is formed on the circular flange of the inner insertion tube body 130, and separated by a predetermined distance from each anti-rotation surface. On both sides, grooves 139 serving as the incision plane portion 133 described in Embodiment 1 are formed inside the circular flange.

The flow path plate coupled to the inner insertion pipe main body 130 of Embodiments 1 and 2 may use a flow path plate that corresponds to a flange formed on each of the inner insertion pipe main bodies, but is shown in FIG. 10A. As shown in the form corresponding to the circular flange before the incision plane portion 133 in which the rotation preventing surface 135 of the inner connecting pipe body 130 is formed is formed in the lower passage passage 160, the through-hole, As shown in FIG. 10B, when the inner insertion tube body 130 and the flow passage plate 160 are fastened, the anti-rotation surface 136 is in contact with the flow passage plate 160, but the anti-rotation surface 136 is provided. Except for the rest, the play is not in contact with the flow plate.

In addition, the shape of the flow path plate of [10a] is not only fastened with the inner tube body of Example 1, but also as shown in [figure 10c] of the circular flange of the inner tube body in Example 2 Compared to the shape of the circular flange of the inner insertion tube body of the first embodiment, the flow path plate as shown in FIG. 10A can be used because there is only a difference between the cut plane portion 133 and the groove 139.

In addition, Fig. 11 and Fig. 12 show another embodiment 3 of the anti-rotation surface of the inner insertion tube body and the anti-rotation locking jaw of the flow path plate.

Several projections of a predetermined shape are formed in the circumferential direction of the inner insertion tube body 130 by the rotation preventing projection 137 at the same position as the rotation preventing surface 136 of the inner insertion tube body 130 described above.

In addition, the rotation preventing groove 167 is dug in a shape corresponding to the rotation preventing projection 137 at the same position as the rotation preventing locking jaw 166 of the flow path plate 160 described above.

In addition, in the fastening structure of the inner insertion pipe main body, the inner insertion pipe upper head, and the outer guide pillar, which are the inner insertion pipes, it is possible to be carried out not by screwing but also by the forced fastening method (Example 4).

Referring to Figure 13,

Outer guide pillar 220 is a hollow cylindrical shape, the upper and lower surfaces are open, the screw 202 is formed from a lower end of the outer surface to a specific height. This is for fastening with the flow path plate 160 to be described later.

From the upper end portion of the outer guide pillar to a predetermined position from the bottom to a shape larger in diameter than the other parts of the outer guide pillar, fastening with the pressing plate (not shown) by the locking step 204 caused by such a diameter difference This is possible.

In addition, the fastening groove 206 is formed on the inner surface of the outer guide pillar. This is used for fastening with the inner insertion pipe which will be described later.

The inner insertion pipe is composed of an inner insertion pipe body 230 and an inner insertion pipe upper head 240.

As shown in FIG. 14, the inner insertion tube body 230 has a hollow cylindrical shape, and the upper and lower surfaces thereof are opened as in the outer guide column 220. Inserted into the inner space of the outer guide pillar 220 in a shape longer than the outer guide pillar 220, the upper portion is the same height as the outer guide pillar 220, the lower portion is protruded longer than the outer guide pillar 220 to be.

The lower portion of the inner insertion tube body 230, the portion protruding out of the outer guide pillar 220 is formed with a screw 232 to a certain height, which is used when combined with the guide tube to be described later.

And the circumferential fastening protrusion 234 is formed. The fastening protrusion 234 is located on the outer surface of the inner insertion pipe body to correspond to the fastening groove 206 formed on the inner surface of the outer guide pillar 220 described above, the inner insertion pipe into the outer guide pillar 220 When the main body 230 is inserted, the fastening is performed by the fastening groove 206 and the fastening protrusion 234.

A plurality of longitudinal cut surfaces 236 are formed from the upper end of the inner insertion tube body 230 by a predetermined length. The longitudinal cutting surface 236 of the inner insertion tube body 230 when the inner insertion tube body 230 is inserted into the outer guide column 220 and fastened by the fastening groove 206 and the fastening protrusion 234. This is to increase the elastic force so that the fastening can be easily made.

In addition, an inner insertion pipe fastening groove 238 is formed on the inner surface of the inner insertion pipe main body 230, which will be described later for coupling with the inner insertion pipe upper head 240.

In addition, a rotation preventing surface 239 is formed at the lower portion of the inner insertion tube body 230.

The anti-rotation surface 239 is positioned above the screw located at the lower portion of the inner insertion tube body 230, and exists in the form of a polygonal border rather than a circular shape. This serves to prevent the occurrence of rotation of the inner insertion tube body 230 when separating the inner insertion tube upper head 240 and the inner insertion tube body 230.

As shown in Figure 15, the inner insertion pipe upper head 240 is fastened to the upper end of the inner insertion pipe main body 230, the shape of the cork stopper having the same shape of the upper and lower parts, but the area is different The upper and lower parts are opened and penetrated.

And the inner insertion tube fastening protrusion 242 is formed on the outer surface of the lower inner insertion tube upper head 240 in the circumferential direction, and when the inner insertion tube upper head 240 and the inner insertion tube body 230 is combined It is located to correspond to the position of the inner insertion pipe fastening groove 238 of the inner insertion pipe body 230.

On the outer surface of the lower portion of the inner insertion tube upper head 240, a fixing protrusion 244 formed with the other protrusion in the circumferential direction is located. This is when the inner insertion pipe 250 and the outer guide column 220 is combined, by pushing the inner surface of the inner insertion tube body 230 to the outside to secure the fastening with the outer guide column 220 Do it.

A plurality of through holes 246 are formed in the lower surface of the inner insertion tube upper head 240 so that a tool or the like can be inserted to easily withdraw the inner insertion tube upper head during disassembly, and a taper at the lower end thereof. The taper 248 is formed to facilitate the insertion or withdrawal of the inner insertion tube upper head 240 into the inner insertion tube body 230.

The fastening of the upper fixing body and the guide tube through such a forced fastening method is such that the forced fastening method is possible even if the rotation preventing surface is formed or not formed because the rotation of the inner insertion tube body is hardly generated.

1-Schematic diagram showing a typical fuel assembly

Figure 2-cross-sectional view showing a conventional top fixture

3-Cross-sectional view showing a conventional guide tube

Figure 4-Incision perspective view showing the fastening of the upper fixing body and the guide tube according to the present invention

Figure 5-Perspective perspective view of the outer guide pillar according to the present invention

Figure 6-perspective view of the internal insertion tube according to the present invention

7-Perspective cutaway view of a flow path plate according to the present invention

8-perspective view of an internal insertion tube according to the first embodiment of the present invention;

9-perspective view of the internal insertion tube according to the second embodiment of the present invention

Fig. 10a-Perspective cutaway view of a flow path plate as an embodiment according to the present invention

Figure 10b-Bottom view showing the coupling of the internal insertion tube and the flow path plate of Example 1 according to the present invention

Figure 10c-Bottom view showing the coupling of the internal insertion tube and the flow path plate of Example 2 according to the present invention

11-a perspective view of an internal insertion tube body according to Embodiment 3 of the present invention;

12-Perspective cutaway view of a flow path plate according to a third embodiment according to the present invention

Figure 13-Perspective cutaway view of the outer guide pillar according to the fourth embodiment of the present invention

14-perspective view of the inner insertion tube body according to the fourth embodiment of the present invention;

Fig. 15-Perspective cutaway view of the internal insertion canal head as Example 4 of the present invention.

<Description of main parts of drawing>

3: guide 120: outer guide pillar

130: inner insertion pipe main body 136: anti-rotation surface

137: anti-rotation protrusion 140: upper head of the insertion tube

150: internal insertion pipe 160: euro plate

162: fastening through hole 166: anti-rotation locking jaw

167: rotation preventing groove 206: fastening groove

220: outer guide pillar 230: inner insertion pipe main body

234: fastening protrusion 236: longitudinal incision surface

238: internal insertion pipe fastening groove 239: anti-rotation surface

240: upper head of the insertion tube 242: fastening protrusion of the inner tube

Claims (5)

A guide tube to which a support grid is fastened in the fuel assembly; A flow path plate positioned at an upper portion of the guide tube and having a fastening hole formed therein, an outer guide column fastened to the fastening hole of the flow path plate by a lower end portion, and a lower end inserted into the outer guide column to fasten the through hole of the flow path plate; Including a top fixing body consisting of an inner insertion pipe penetrating through and an inner insertion pipe head coupled to the upper end of the inner insertion pipe and the outer guide pillar to interconnect the inner insertion pipe and the outer guide pillar, Rotation of the inner insertion tube body when the inner insertion tube head is rotated at any one or more of the connection portion between the connection hole of the inner insertion tube and the flow path plate, the upper portion of the inner insertion tube head, the inner insertion tube body, and the outer guide pillar. Fastening structure of the guide tube and the top fixing body, characterized in that the rotation preventing means for preventing the provided. The method of claim 1, The rotation preventing means, An anti-rotation surface of a horizontal plane formed locally on the outer circumferential surface of the inner insertion pipe body; The fastening structure of the guide tube and the upper fixing body, characterized in that made of a horizontal anti-rotation locking jaw formed in the contact point with the anti-rotation surface of the inner circumferential surface of the fastening through-hole of the flow path plate. The method of claim 1, The rotation preventing means, An anti-rotation protrusion of a horizontal plane formed locally on the outer circumferential surface of the inner insertion pipe body; The fastening structure of the guide tube and the upper fixing body, characterized in that made of a rotation preventing groove of the horizontal plane form formed at the point of contact with the rotation preventing projection of the inner circumferential surface of the fastening through-hole of the flow path plate. The method of claim 1, The inner insertion tube upper head is inserted into the inner insertion tube body, The inner insertion pipe upper head is coupled to each other in a form that is inserted into the outer guide pillar, One of the inner circumferential surface of the inner insertion pipe upper head and the inner circumferential surface of the inner insertion pipe main body has a fastening protrusion formed therein, and the other side of the inner fastening groove is formed with a fastening groove into which the fastening protrusion is inserted. One of the inner peripheral surface of the inner insertion tube upper head and the inner peripheral surface of the outer guide tube pillar is formed in the form of a fastening protrusion protruding, and the other end of the guide tube and the upper stationary body Fastening structure. The method of claim 4, wherein The inner insertion tube body is a fastening structure of the upper end of the nuclear fuel assembly and the guide tube formed with a cutting plane in the axial direction from the upper end.

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