KR820000896B1 - Grappble control for fuel fitting structure - Google Patents

Abstract

The grapple (56) releases the lock (21) from the control rod guide tube sleeves (17) and also provides a means for installing or removing as one entire unit the complete assembly that comprises the lock, washer, spider, spring and grill. To accomplish these results, the grapple is provided with a number (57) that is movable in the direction of longitudinal axis. The jaw (70) is provided at its extreme end with a clamp (73) that engages a longitudinal edge of the grill. In a similar manner, the extreme end of the jaw (67) also is provided with a clamp (74) that is oppositely disposed from the clamp on the jaw (70).

Description

Adjustment grapples for end fixtures in fuel assemblies

1 is a partial cutaway front view of a typical fuel assembly embodying the principles of the present invention.

2 is a cross-sectional view of a control rod guide tube for use in the structure shown in FIG.

3 is a plan view showing the planar portion of the control rod guide tube shown in FIG. 2 along the 3-3 line direction in FIG.

4 is a front view of a grapple and tool that couples a portion of the nuclear fuel assembly shown in FIG.

FIG. 5 is a plan view cut away of a portion of the grapple shown in FIG.

6 is a front view showing the initial working position of the grapple.

7 is a front view showing the intermediate working position of the grapple.

8 is a front view showing the continuous intermediate working position of the grapple.

9 is a front view showing a part of the grapple after the ruler is released.

FIELD OF THE INVENTION The present invention relates to nuclear fuel assemblies for use in nuclear reactors, and more particularly, to regulating grapples for end fixtures of control rod guide tubes within a nuclear fuel assembly.

To generate effective power from the reactor, it is necessary to assemble the fissile material in a state that is sufficiently concentrated to slow down the continuous fission by the neutrons.

The concentration of these fissile materials can be maintained by sealing the uranium dioxide fuel pellets in a thin, long rod, which is called a "nuclear fuel rod" when the fuel is charged and sealed at both ends.

Nuclear fuel rods are arranged in columnar arrangements within the reactor to achieve a desired concentration of fissile material.

In order to extract the heat generated from these fuel rods during the nuclear fission process, the fuel rods are arranged to maintain a constant space laterally and pressurized coolant is forced through the reactor core.

The coolant absorbs the heat generated during the nuclear fission process and transfers it to the secondary coolant, which generates steam that drives the turbine unit for power generation.

Radiation, pressure, temperature, and coolant flow rates within the reactor core create an environment that is very poor for the texture of the reactor core structure. To overcome this environment, nuclear fuel rods are usually arranged to form the reactor core with a plurality of nuclear fuel rod groups of about 200 as a group, usually referred to as a fuel assembly.

In order to improve the structural shape of each fuel assembly and to stabilize the fuel rods within the fuel assembly, the fuel rods are generally placed between the “end holders” and the middle of each fuel rod of the fuel assembly is in the middle of a predetermined intermediate along the length of the fuel rod. It is bound by the cell-like lattice structure that is located.

Furthermore, the fuel assembly is not limited to fuel rods, end fixtures and lattice structures, one or more control rod guide tubes being installed in the fuel assembly.

In general, neutron absorbers are incidentally used in the reactor core to control the power generated within the reactor. Such neutron absorbing materials have the effect of reducing the nuclear fission in the reactor core, thereby reducing the power generated from the reactor.

There may be various ways to install such neutron absorbers in the reactor core. However, neutron absorbers are usually loaded into the control rod.

These control rods are inserted into hollow metal control rod guide tubes extending the length of each fuel rod.

Under these conditions, the depth of insertion of the control rod into its associated fuel rod determines the neutron fission and output from the reactor core.

In some fuel assembly designs, control rod guide tubes are used after the control rods are individually arranged within each fuel assembly. In this regard, the control rod guide tubes are respectively located in the space between the two end fixtures and the rods can be held in the appropriate relative position between these end fixtures so that the end locks can engage the end of the nuclear rods. Used.

The structure of such fuel assemblies can be constructed robustly to the reactor core, but fuel assemblies that are easy to assemble and disassemble must be made to reduce manufacturing costs, improve quality assurance, and facilitate inspection and replacement.

If there is a release of radiation from the fuel assembly, it will have to be controlled by a remotely operated device behind the shield, and the need for the introduction of a simple disassembly technique will prove immediately important.

At this point, a typical fuel rod is disassembled by unscrewing the knit connecting the control rod guide tube to the end fixture, releasing one or more springs, and then separating the complete fuel assembly into parts.

This is not only cumbersome and costly, but it can also lead to the loss or loss of several small fixtures and cost and, if not found, costly.

As such, the prior art requires a new fuel assembly that can overcome a wide range of these inadequate problems.

The novel fuel assembly according to the principles of the present invention is characterized by the construction of a sleeve that couples one end of the control rod guide tube, essentially a sleeve for securing the guide tube to one end of the end structure of the fuel assembly.

The end of the sleeve protrudes over the surface of the end fixture and the outer surface of the sleeve has a perimeter requirement that is coupled to the elastic side of the cell grid or grate shaped ruler.

This locking device secures the sleeve between the various components, including the end fixture, thereby eliminating the costly and prone to failure of the nut frequently used in conventional fuel assemblies. .

In accordance with the principles of the present invention, a special grapple having jaws engaging a portion of the end fixture to disassemble the end fixture from the fuel assembly is provided. Holding the ends and the upper gratings supporting their respective sleeves, the spiders, which engage the sleeves of the control rod guide tube, maintain these longitudinal slits between the spider and the stopper portions. Press the spring inserted into the eve.

After such spacing, individual tools are pressed into individual open protrusions of each sleeve to engage the exposed portions of the grid ruler.

The tool will squeeze these sides from the request and engage the ruler so that the ruler will leave the sleeve when the grapple is withdrawn from the end of the fuel assembly.

This tool allows you to lift the upper end fixture, such as the unit holding the component combined with the end fixture, while removing the sleeve combined with the control rod guide tube and the rest of the fuel assembly. do.

In this way, the end fixture configuration held by the grapple does not damage the fuel assembly without the hassle or cost of remote controllers from disassembling and assembling the problems associated with small components, which has been a problem in the prior art. No, it can be replaced.

As described above, the present invention provides a technology capable of reducing the number of parts required for constructing a fuel assembly, and can reduce manufacturing costs and simplify quality assurance and inspection problems.

Numerous unique forms that characterize the invention are pointed out in detail in the claims appended to and constitute the specification.

When described in detail by the accompanying drawings for a better understanding of the present invention.

As shown in FIG. 1, the fuel assembly 10 consists of an array of 200 or more nuclear fuel rods 11, which are thin, long, thin tubs in which uranium dioxide particles or other suitable fuels are melted. These fuel rods are all made of bro, and the fuel rods are grouped in parallel in the fuel assembly 10 along the longitudinal axis.

The control rod guide tube 12 is positioned between the nuclear fuel rods, and each control rod guide tube 12 is a hollow, thin tube that extends for the entire length of the fuel assembly in parallel along the longitudinal axis of the fuel assembly. have.

An end support fixture 13 disposed transversely with respect to the longitudinal axis of the nuclear fuel rod 11 is engaged with an adjacent end of the nuclear fuel rod, and the control rod guide tube 12 attaches the end fixture to the fuel assembly structure. It passes through the end fixture 13 in order to.

The ends of the control rod guide tube 12 protrude above the plane formed by the sealing end of the nuclear fuel rod 11, and the protruding ends of these control rod guide tube 12 are horizontal lattices 14 as shown in FIG. Ending at the end).

The grating 14 is assembled as a parallel arrangement of flat plates in which a demand is formed to be coupled with a coupling requirement formed in a vertical arrangement of flat plates to form a cellular grid structure. The parallel cluster configuration of the nuclear fuel rod 11 and the control rod guide tube 12 is stably configured by a lateral lattice structure 15 similar to the structure of the grid 14 already mentioned.

However, the upper lateral lattice 16 is located towards the end of the nuclear fuel rod 11 adjacent to the protrusion of the control rod guide tube. The upper lattice 16 is deeper in the longitudinal axis of the fuel rod 11 than the lattice structure 15 to improve the structural texture of this portion of the fuel assembly.

The hollow cylindrical sleeve 17 extends to the upper lattice 16 through the lattice 14, the horizontal spider 20, and the guide rod guide tube assembly ruler 21 adjacent thereto. They overlap each protruding end of the guide tube 12. Each sleeve 17 has a coil spring 22 between the grating 14 and the spider 20 to compensate or absorb the movement of the fuel assembly 10 in the direction of the longitudinal axis of the fuel rod 11. It is snowballed.

As shown in FIG. 2, the sleeve 17 is arranged in line with the guide tube 12 in the axial direction, and the sleeve serves as a guide of the coil spring 22, and the coil spring 22 is It has a longitudinal axis coinciding with the longitudinal axis of the guide tube.

Figure 2 shows the characteristic structure of the present invention in more detail, the control rod guide tube 12 is installed on the lower grid 23 by the bolt structure 24, the bolt structure 24 is the control rod It has a head 25 received in the adjacent open end of the guide tube 12.

The bolt body 26 extends through the lower lattice 23 so as to protrude from the end support body 13, and the protruding portion of the body 26 is formed with a spiral to fix the fixing nut 27.

A nut stator 30 is inserted between the end fixture and the nut 27 to prevent the nut from loosening or detaching from the fuel assembly during operation.

As shown in FIG. 2, the control rod guide tube 12 extends through the major portion of the fuel assembly and the upper lattice 16, and within the upper lattice 16 the guide tube 12 is a sleeve (see FIG. The open end in the control rod guide tube 12 superimposed in 17 is bound to a shoulder 32 formed in the inner surface of the sleeve 17. The shoulder 32 of the sleeve 17 transmits the compression load directly to the guide tube.

The overlapping portion of the control rod guide tube 12 and the sleeve 17 forms a “projection” 33 projecting outwardly in an appropriate manner in order to securely connect both the sleeve and the guide tube. A ring-shaped collar 34 is installed which limits a portion of the sleeve 17 just below the grating 14 and is supported on the transverse surface of the grating 14.

The collar 34 and sleeve 17 and the recessed portion of the control rod guide tube 12 are positioned in the longitudinal direction of the control rod guide tube by positioning the collar 34 relative to the balance of the fuel assembly structure. Protrusions 35 and 36 are formed to allow the collar to bear and transfer this load between the sleeve 17 in combination with the grating 14 and the control rod guide tube 12. The washer 40 surrounds a portion of the sleeve 17 protruding upward of the horizontal lattice 14 to which the collar 34 is coupled. In general, the longitudinal axis of the coil spring 22 coincides with the longitudinal axis 37 to apply pressure to the other washer 41. The washer 40 is coupled to the cellular spider assembly 20, and the sleeve 17 is configured to allow the spider and the sleeve to move relative to each other in the direction of the longitudinal axis 37. It is collected in the cellular holes 42 of the spider 20 having a gap between the wall surfaces.

The end portion 43 of the sleeve 17 protrudes upward of the spider 20 to engage with the ruler 21.

In order to engage with the ruler 21, an outer surface of the end portion 43 is formed with an annular demand 44 for forming a protruding shoulder 45 to act to engage with the edge of the ruler 21.

As shown in detail in FIG. 3, the ruler 21 is mutually coupled with similar elastic plates 50 and 51 perpendicular to the plates 46 and 47 at the intersection to form a cell-like lattice structure. As shown in the figure. The gap between the parallel plate bodies 46 and 47 is as shown in the figure, and the maximum outer diameter of the request 44 formed in the end portion 43 is shown. Is less than

The plate body 50 is formed with a jade-shaped portion that can limit and support a portion of the sleeve end portion 43 is formed, but the pair of plate body 51 is able to couple the shoulder 45 It has a flat portion (Figure 2).

In this way, the control rod guide tutes shown in FIG. 1 are all composed of one single unit.

As described in more detail in FIGS. 2 and 3, the end portion 43 is formed with four longitudinal requests 52, 53, 54, 55 parallel to the longitudinal axis 37, Each of these demands 52, 53, 54, 55 are arranged at intervals of about 90 ° to each other, the depth of which is combined with the combined longitudinal depth of the shoulder 45 and the width of the plate 50, 51. It is at least the same depth.

4 shows the grapple 56, which is an additional form of the present invention, and the grapple 56 releases the ruler 21 from the sleeve 17 of the control rod guide tube and the ruler 21. Assembly as one complete device consisting of a sleeve 17, a spider 20, a coil spring 22 and a grating 14 in combination with a control rod guide tube 12 (not shown in FIG. 4). It provides a means for installing or removing it.

In order to achieve this result, the grapple 56 has a member 57 which is movable in the direction of the longitudinal axis 60, and the horizontal connector 61 passes through the cross member (figure 5) and the vertical movable member 57. ) Is installed. At the ends of the connector 61 (FIG. 4), requests 63 and 64 are formed to accept the pins 65 and 66, respectively. Pins 65 and 66 are adapted to move transversely within each request for two jaw physics 67 and 70 rotatably connected to lateral tool frame 71 to act like scissors. .

Such a shaft 72 connects the jaw stopper 70 to the tool frame 71. As shown in FIG. 4, a clamp 73 is formed at the outermost end of the jaw stopper 70 and is coupled to the edge of the grating 14. Similarly, at the outermost end of the jaw 67. A clamp 74 is provided which is disposed opposite the clamp 73 of the jaw iris 70.

In FIG. 5, a paired connector 75 with jaw chucks 76 and 77 staked out with pins is also connected to the longitudinally movable member 57 by means of a cross member 62, the opposite pair. The structure of is to stabilize and balance the structural bale state as described above with respect to the jaw stops 67 and 70.

In addition, the horizontal tool frame 71 is formed with a barrel of a through hole 80 that is longitudinally received to accommodate a group of tools 81. As shown in FIG. 4, the tool 81 is configured in the form of a cylindrical rod that is paralleled with the axis 60, and the tool 81 generally has a conical end 82.

The middle part of the tool 81 has four projections 83 in which three projection ends are indicated in the figure.

Each projection 83 is rolled to a position of 90 degrees each, and has a tapered inclined portion 84 that is inclined toward the end portion 82. Tapered inclined portion 84 generally ends in planar portion 85, and the width of each projection 83 is transverse to the demands 52, 53, 54, 55 (FIGS. 2 and 3). Slightly smaller than the direction width

However, the transverse depth of each of these projections between the planar portion 85 (FIG. 4) and the adjacent surface portion of the tool 81 is shown by the end portion 43 of the sleeve as shown in FIGS. Greater than the wall thickness

The annular collar 86 is mounted on the tool 81, and the projections maintain a constant distance when they are arranged in a line so that they can be supported toward the ends within each request formed in the ends 43 of the sleeve. The planar portion 85 of the 83 can prevent the sleeve 17 from penetrating deeper than the longitudinal depth of the request formed in the sleeve end 43 of the upper portion of the spiro 20. To form a constant space in the longitudinal direction.

As shown in FIG. 4, the compressed air cylinders 95 and 96, which are spring-biased at the end 82 opposite the end 82 of the tool 81, are adjusted in the longitudinal direction shown by arrows 93 and 94. It has a spiral portion 87 for fixing the nuts 90 and 91 in order to install the tool 81 on the movable horizontal plate member 92. According to the relative movement of the compressed air cylinders 95 and 96, the flat portion 85 formed in the projection 83 when the tool 81 is arranged in line with the sleeve end portion 43 is the plate body 46. (47) 50 and 51 are driven into the sleeve 17 to a sufficient depth to be supported (FIGS. 2 and 3). The planar portion 83 presses these plates in the radially outward direction with respect to the longitudinal axis 37 so that all the plates can remove the gap from the shoulders 45 formed in the sleeve end 43. In this way the complete cellular ruler 21 is released in engagement with the sleeve 17 and itself is fixed to the tool 81.

In operation, as shown in FIG. 6, the grapple 56 is clamped with the clamp 73 of the jaw claw 70 (not shown in FIG. 6 with the clamp 74 of the jaw claw 67). Like the clamps of (76) and (77)] are arranged in line with the end fixture so that it can come out of the grating 14, but in the same transverse plane as the grating.

In this operating state of the grapple 56, the spring combined with the spring ball pin 97 is compressed by the action of the compressed air cylinder 95 which moves the plate 92 in the direction of the arrow 93.

In FIG. 7, the clamps 73 and 74 of the jaw claws 70 and 67 (also with the clamps of the pair of jaw claws 76 and 77) securely secure the periphery of the grating 14. It is contracted inwardly in the direction indicated by arrows 101 and 102 to catch it.

Inward contraction of the clamps 73, 74 can be achieved by moving the member 57 longitudinally upwards in the direction of the arrow 103, the movement of the member 57 being the pins 65, 66. With each request (63) (64) is retracted towards the longitudinal axis (60), the movement of the pins within these requests is such that the jaw claws (67) (70) are rotated counterclockwise or clockwise (72). Each of the jaw stoppers 70 is forcedly rotated, and the shaft of the jaw claw 67 (not shown in FIG. 7) is also rotated as described above.

FIG. 8 shows the next step of the technique for disassembling the end fixture from the fuel assembly, whereby the compressed air cylinder 96 moves the piston rod 104 in the direction indicated by the arrow 105 and the exposed piston rod. The end of the 104 is pressed against the transversely adjacent surface of the spider 20, and the force applied to the spider 20 by the piston rod 104 is applied to the opposite side set by the coil spring received in the sleeve. More than a force, the coil spring 22 and the sleeve 17 are shown in FIG.

In the direction of the arrow 105 to provide a longitudinal gap between the spider 20 and the ruler 21 to represent the force exerted on the ruler 21 of the spider 20 according to this new balance of forces. Move.

9 shows a continuous working state of the grapple 56, and the request 44 formed at the sleeve end portion 43 so that the cellular structure of the ruler 21 resumes movement (FIG. 2). And shoulders 45 engage with plate bodies 46, 47, 50, 51 (FIG. 3) constituting the cellular structure in the gwaeum 21. The compressed air cylinder 95 disassembles the coil spring on the spring bullet pin 97 to release and compress the plate body 92 in the direction of the arrow 107. The tool 81 secured to the plate body 92 with the demands and shoulders of the sleeve supporting any movement in the direction of the arrow 107 is typically through an independent cellular space within the ruler 21. Each sleeve 17 is pressed. In addition, the projections 83 radially projecting in the tool 81 are inserted into the insertion requests 52, 53, 54, 55 (FIGS. 2 and 3). This longitudinal movement of the tool 81 is such that the pin 83 (FIG. 9) releases the combined plate body in the annular demand 44 (FIGS. 2 and 3) formed at the sleeve end 43. FIG. The tapered demands 84 are to press the plates 46, 47, 50 and 51 of the ruler 21 in the radially outward direction.

At this time, the longitudinal movement of the tool 81 (FIG. 9) in the direction of the arrow 107 under the elasticity of the released spring on the pin 97 is limited only by the braking action of the collar formed on each tool.

Since the collar 86 has a constant angle with respect to the ruler part 21, the plate which forms each cellular space in the ruler part 21 exerts a force on the flat part 85 of the projection 83. As shown in FIG.

This coupling effect between the plate body forming the cellular space in the ruler 21 and the planar portion 85 of the protrusion 83 is characterized by the annular demand 44 (FIGS. 2 and 3) and shoulder 45. Press the plate body to be bonded.

Using the following description as a disassembly step, the complete grapple 56 moves in the longitudinal direction indicated by arrow 108 and the grapple withdrawing from the fuel assembly in the manner described above has the majority of the end fixtures at their own relative positions. Extract the components.

The ruler 21, the spider 20 and the grating 14 remain in the grapple 56, and the coil spring 22 and the washers 40 and 41 (FIG. 2) coupled thereto are also grapples. (56) (FIG. 9).

Instead, the tool serves as a provisional spring for guiding or supporting the coil spring 22 and washer. Moreover, the spring 22 acts to maintain an approximately inherent longitudinal separation between the grating 14 and the spring 20, in which the sleeve 17 remains in the remainder of the fuel assembly.

In order to reassemble the components of the end fixture in the major part of the fuel assembly, the ends of the tools 81 installed in the grapple 56 are arranged in a longitudinal line with their respective sleeves and then the grapple 56 ) Moves longitudinally in the direction of arrow 107 until each tool 81 is fully seated in each sleeve 17.

One or more clamps (not shown) support the ruler 21 in an appropriate position relative to the request 44 (FIGS. 2 and 3) and the shoulders 45 on the sleeve end 43. Support.

At this time, the cylinder 95 (FIG. 9) acts to compress the spring on the spring bullet pin 97, and pulls out the pin 83 in a state coupled with the plate body forming the cellular space in the ruler 21. .

Separation of the tool 81 and the ruler 21 is a shoulder formed on the annular demand 44 (FIGS. 2 and 3) and the sleeve end portion 43 forming the cellular space of each ruler. To 45 again. Under the action of the coil spring 22, the spider 20 (FIG. 9) abuts against an adjacent surface of the ruler 21, and furthermore, the member 57 has a jaw stop 67 and 70 respectively clocked. It moves in the longitudinal direction of the arrow 107 so that it can rotate counterclockwise.

This rotational movement of the jaw stoppers 6 and 70 causes the clamps 73 and 74 to release the grating 14 and other clamps (not shown) are also moved from the ruler.

As such, the complete end fixture is reassembled into the fuel assembly in such a way that it completely avoids the drawbacks of bothersome prior art and component parts being disassembled and reassembled one by one.

This technique, which characterizes the present invention, also eliminates the conventional drawbacks that make it easy to lose small parts of the end fixture.

Claims (1)

A grapple for adjusting an end lock for a fuel assembly including a control rod guide tube, the longitudinally movable limb 57, a transverse cross member 62 connected to the longitudinally movable member, mounted to the cross member and internally Two jaws (61) and (77) having lateral demands on the lateral connection, and two jaws slidably connected to each of the above lateral connection requests and rotatably connected to a tool frame arranged laterally with respect to the member. Physically 67, 70, 76, 77 and clamps 73, 74, 76, 77 formed separately on the jaw physics to selectively grip the end fixture of the nuclear fuel assembly. And a grapple for adjusting the end lock for the nuclear fuel assembly by shrinking the end lock to engage the member and allowing the cross member and the connector to move longitudinally.

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