Fuel cladding scouring experiment device and guide pipe centering and fixing method

Abstract

The invention discloses a fuel cladding scouring experiment device and a guide pipe centering and fixing method. The fuel cladding scouring experiment device comprises an inlet section, an outlet section, a centering and fixing tool and a guide pipe. The inlet section and the outlet section are oppositely arranged at an interval, the centering fixing tool is vertically connected between the inlet section and the outlet section, and a centering fixing channel is formed in the centering fixing tool; the guide pipe is fixed in the centering fixed channel in a centering manner and is vertically connected between the inlet section and the outlet section; and the guide pipe is respectively communicated with the inlet channel of the inlet section and the outlet channel of the outlet section. Through cooperation of the inlet section, the outlet section, the centering fixing tool and the guide pipe, centering adjustment and multi-point fixing are carried out on the slender guide pipe at the same time; the guide pipe is used as a flow channel, an experiment sample piece is hung in the guide pipe, an experiment is carried out by simulating the flow state in a reactor, and the design problem of an ATF cladding pipe scouring experiment device is solved.

Description

Technical Field

[0001] This invention relates to the field of experimental research technology of reactor thermal-hydraulic systems, and in particular to a fuel cladding scouring experimental apparatus and a method for centering and fixing a guide tube. Background Technology

[0002] The reactor interior environment is extremely harsh. Before the ATF cladding tube is officially inserted into the fuel assembly guide tube for testing, a series of experimental studies must be conducted outside the reactor. These studies include subjecting the sample suspended in the guide tube to long-term water scouring to evaluate its scouring resistance. Therefore, the scouring test apparatus must be able to simulate the suspension and scouring conditions of the sample in the prototype guide tube and possess the ability to monitor vibration in real time. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a fuel cladding scouring experimental device and a method for centering and fixing the guide tube.

[0004] The technical solution adopted by the present invention to solve its technical problem is: to provide a fuel cladding scouring test device, including an inlet section, an outlet section, a centering and fixing fixture set in a simulated fuel assembly grid, and a guide tube with a slender structure for suspending the test sample therein; The inlet section and the outlet section are arranged at relative intervals. The centering fixing fixture is vertically connected between the inlet section and the outlet section. The centering fixing fixture is provided with a centering fixing channel. The guide tube is centered and fixed in the centering fixing channel and vertically connected between the inlet section and the outlet section. The guide tube is connected to the inlet channel of the inlet section and the outlet channel of the outlet section, respectively.

[0005] Preferably, the centering fixing fixture includes a first base, a second base, multiple fixing rods, and multiple sets of positioning components; The first base and the second base are arranged at intervals relative to each other. Multiple fixing rods are arranged in parallel and vertically connected between the first base and the second base. Multiple positioning components are located in the space enclosed by the multiple fixing rods, and are arranged at intervals along the axial direction of the fixing rods and connected between the multiple fixing rods.

[0006] Preferably, the positioning component includes a positioning seat with a central positioning hole and multiple connecting segments arranged at intervals and connected to the circumference of the positioning seat; each connecting segment is connected to a corresponding fixing rod; the central positioning holes of the positioning seats of the multiple sets of positioning components are sequentially connected to each other to form the centering fixing channel.

[0007] Preferably, the plurality of fixing rods are four fixing rods; the positioning seat is provided with four connecting sections in the circumferential direction.

[0008] Preferably, the positioning seat is further provided with at least one adjusting screw, the adjusting screw being radially inserted into the positioning seat, and the tail end of the adjusting screw protruding into the central positioning hole; The adjusting screw can move back and forth axially relative to the positioning seat, adjusting the length of its tail end within the central positioning hole to press against or move away from the guide tube.

[0009] Preferably, the first base is a circular ring structure; the second base includes a plurality of fixing blocks, which are spaced apart on the inlet section and avoid the bolts on the inlet section; one end of each fixing rod is fixed to a fixing block, and the other end is fixed to the first base.

[0010] Preferably, the inlet section includes an inlet pipe section, an inlet flange disposed at at least one end of the inlet pipe section, and a first sealing flange disposed on the surface of the inlet flange; the first sealing flange is provided with a first central hole, which communicates with the central stepped through hole of the inlet flange; one end of the guide pipe passes through the first central hole and is inserted into and positioned in the central stepped through hole of the inlet flange.

[0011] Preferably, the outlet section includes an outlet pipe section, an outlet flange disposed at at least one end of the outlet pipe section, and a second sealing flange disposed on the surface of the outlet flange; the second sealing flange is provided with a second central hole, which communicates with the central stepped through hole of the outlet flange; one end of the guide pipe passes through the second central hole and is inserted into and positioned in the central stepped through hole of the outlet flange.

[0012] Preferably, the outlet section further includes a branch pipe radially connected to the outlet pipe section, and the outlet channel of the outlet section passes through the branch pipe.

[0013] The present invention also provides a method for centering and fixing a guide tube, thereby achieving the centering and fixing of the guide tube within the centering and fixing fixture in the fuel cladding flushing experimental device described in any of the above claims; the method for centering and fixing the guide tube includes the following steps: S1. Place the centering fixing fixture vertically, insert the guide tube and initially fix it in the centering fixing channel of the centering fixing fixture; the first base of the centering fixing fixture faces upward; S2. Arrange multiple hammer wires at intervals along the circumference of the guide tube, and pass them from the bottom of the guide tube into the centering and fixing channel from bottom to top. After the hammer wires pass through the centering and fixing channel, they are fixed to the hammer wire fixing fixture set above the guide tube. S3. The hammers of the multiple hammer lines are staggered in the axial direction of the guide tube, so that the lower ends of the guide tube and the hammer lines are suspended in the air; S4. Adjust the bottom surface of the second base of the centering fixture using a standard feeler gauge to make the surface of the first base of the centering fixture horizontal, and confirm that the plumb line hangs down naturally and the plumb bob does not interfere. S5. Check the plumb line between the uppermost positioning component and the plumb line fixing device in the centering fixing fixture, adjust the adjusting screw on the positioning component to make the plumb line fit against the outer wall of the guide tube, and then tighten the adjusting screw. S6. Adjust the adjusting screws of each positioning component from top to bottom in sequence so that the hammer line fits against the outer wall of the guide tube, and then tighten the adjusting screws until the adjustment of all positioning components is completed.

[0014] Preferably, in step S3, a support and fixing component is used to support and position the second base of the centering fixing fixture, so that the centering fixing fixture is erected and the lower ends of the hammer line and the guide tube are suspended.

[0015] Preferably, the support and fixing member includes an H-beam short section.

[0016] The beneficial effects of this invention are as follows: By coordinating the inlet section, outlet section, centering and fixing fixture, and guide tube, the slender guide tube can be simultaneously adjusted for centering and fixed at multiple points. Using the guide tube as a flow channel, experimental samples are suspended inside the guide tube to simulate in-reactor flow conditions, thus solving the design challenges of the ATF cladding tube scouring experimental device. The simultaneous centering and fixing of the slender guide tube using the centering and fixing fixture solves the centering and fixing problem when the guide tube is installed vertically. This invention can conduct long-cycle scouring experiments on experimental samples of different specifications, adapting to the full-cycle experimental needs of accident-tolerant fuel development. Attached Figure Description

[0017] The present invention will be further described below with reference to the accompanying drawings and embodiments. In the accompanying drawings: Figure 1 This is a three-dimensional structural schematic diagram of a fuel cladding scouring experimental device according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the inlet section of a fuel cladding scouring experimental apparatus according to an embodiment of the present invention; Figure 3 This is a schematic diagram of the outlet section of a fuel cladding scouring experimental apparatus according to an embodiment of the present invention; Figure 4 This is a schematic diagram of the centering and fixing fixture in a fuel cladding scouring test apparatus according to an embodiment of the present invention; Figure 5 yes Figure 4 The diagram shows the structure of the second base in the centering and fixing fixture. Figure 6 yes Figure 4The diagram shows the structure of the positioning component in the centering and fixing fixture. Figure 7 This is a schematic diagram of the process structure of a guide tube centering and fixing method according to an embodiment of the present invention; Figure 8 This is a schematic diagram of the structure in which the experimental sample is suspended in the guide tube by the sample fixing fixture in this invention. Detailed Implementation

[0018] To provide a clearer understanding of the technical features, objectives, and effects of the present invention, specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0019] like Figure 1 As shown, the fuel cladding scouring experimental apparatus of the present invention includes an inlet section 10, an outlet section 20, a centering and fixing fixture 30, and a guide tube 40 with a slender structure.

[0020] The inlet section 10 and outlet section 20 are arranged at intervals. A centering fixture 30, simulating a fuel assembly grid, is vertically connected between the inlet section 10 and outlet section 20. The centering fixture 30 has a centering channel, and a guide tube 40 is fixed within this channel and vertically connected between the inlet section 10 and outlet section 20. The guide tube 40 is connected to both the inlet channel in the inlet section 10 and the outlet channel in the outlet section 20.

[0021] In the experimental apparatus of the present invention, the guide tube 40 is used as a flow channel, and the experimental sample is suspended in the guide tube 40 to simulate the flow state in the pile and carry out the experiment.

[0022] In some embodiments, reference Figure 1 and Figure 2 The inlet section 10 includes an inlet pipe section 13, at least one inlet flange 11, and a first sealing flange 12; the inlet channel is formed within the inlet pipe section 13. Inlet flanges 11 are also provided at opposite ends of the inlet pipe section 13. The first sealing flange 12 is disposed on one of the inlet flanges 11 facing the outlet section 20 of the inlet pipe section 13, and further disposed on the surface of the inlet flange 11 facing the outlet section 20, for fixing the guide pipe 40 to the inlet section 10 when it mates with one end of the guide pipe 40.

[0023] Specifically, the first sealing flange 12 can be connected to the inlet flange 11 by screws. The first sealing flange 12 has a first central hole, which communicates with the central stepped through hole of the inlet flange 11. One end of the guide tube 40 passes through the first central hole and is inserted and positioned in the central stepped through hole of the inlet flange 11.

[0024] The lower inner diameter of the stepped central bore of the inlet flange 11 is smaller than the outer diameter of the guide tube 40 to receive the end of the guide tube 40 and prevent the guide tube 40 from penetrating the inlet flange 11. Pressure boundary sealing is achieved between the first sealing flange 12 and the inlet flange 11, the end of the guide tube 40 and the stepped central bore, etc., through an annular sealing groove and an O-ring. As the screws between the inlet flange 11 and the first sealing flange 12 are tightened, the O-ring is further compressed, ultimately connecting the guide tube 40 to the inlet flange 11.

[0025] In some embodiments, reference Figure 1 and Figure 3 The outlet section 20 includes an outlet pipe section 23, at least one outlet flange 21, and a second sealing flange 22; the outlet channel is formed within the outlet pipe section 23. Both ends of the outlet pipe section 23 are also provided with outlet flanges 21. The second sealing flange 22 is disposed on the outlet flange 21 of the outlet pipe section 23 facing the inlet section 10, specifically on the surface of the outlet flange 21 facing the inlet section 10, and is used to fix the guide pipe 40 to the outlet section 20 when it mates with one end of the guide pipe 40.

[0026] Specifically, the second sealing flange 22 can be connected to the outlet flange 21 by screws. The second sealing flange 22 has a second center hole, which communicates with the center stepped through hole of the outlet flange 21. One end of the guide tube 40 passes through the second center hole and is inserted and positioned in the center stepped through hole of the outlet flange 21.

[0027] The lower inner diameter of the stepped central bore of the outlet flange 21 is smaller than the outer diameter of the guide pipe 40 to receive the end of the guide pipe 40 and prevent the guide pipe 40 from penetrating the outlet flange 21. Pressure boundary sealing is achieved between the second sealing flange 22 and the outlet flange 21, the end of the guide pipe 40 and the stepped central bore, etc., through an annular sealing groove and an O-ring. As the screws between the outlet flange 21 and the second sealing flange 22 are tightened, the O-ring is further compressed, ultimately connecting the guide pipe 40 to the outlet flange 21.

[0028] Furthermore, the outlet section 20 also includes a branch pipe 24, which is radially connected to the outlet pipe section 23. The outlet channel of the outlet section 20 passes through the branch pipe 24 to allow fluid to flow out from the branch pipe 24. The outlet flange 21 of the outlet pipe section 23 facing away from the inlet section 10 is provided with a vent 25, which communicates with the outlet channel.

[0029] Since the guide tube 40 is a thin-walled, slender metal tube approximately 4 meters long, and its two ends are connected to the inlet section 10 and the outlet section 20 respectively, when it is vertically installed on the experimental platform, the overall structure is not stable. The guide tube 40 will bend or tilt, which is inconsistent with its installation state in the prototype fuel assembly. To address this, the present invention provides a centering and fixing fixture 30 between the inlet section 10 and the outlet section 20. The centering and fixing fixture 30 has multiple functions, including connecting the inlet and outlet flanges, centering adjustment, and simulating the fixing of the prototype fuel assembly grid position.

[0030] Combination Figure 1 and Figure 4 The centering and fixing fixture 30 may specifically include a first base 31, a second base 32, multiple fixing rods 33, and multiple sets of positioning components 34. The first base 31 and the second base 32 are arranged at intervals relative to each other. The multiple fixing rods 33 are arranged parallel to each other and vertically connected between the first base 31 and the second base 32. The multiple positioning components 34 are located within the space enclosed by the multiple fixing rods 33, and are arranged at intervals along the axial direction of the fixing rods 33 and connected between the multiple fixing rods 33. A centering and fixing channel is formed between the multiple positioning components 34, and a guide tube 40 is located within the centering and fixing channel and connected between the inlet section 10 and the outlet section 20.

[0031] The first base 31 is preferably configured as a circular structure according to the flange face installation space of the outlet flange 21, and is fixed to the flange face of the outlet flange 21 by screws.

[0032] The second base 32 avoids bolt interference on the flange face of the inlet flange 11, and is preferably an irregularly shaped structure. A corresponding limiting groove 110 is provided on the flange face of the inlet flange 11 (e.g., Figure 2 As shown), it is used for limiting the second base 32 during installation to ensure installation accuracy. In some embodiments, such as Figure 2 , Figure 4 and Figure 5 As shown, the second base 32 includes multiple fixing blocks 321, which are spaced apart on the inlet flange 11 of the inlet section 10, avoiding the bolts on the inlet flange 11 and being limited within the corresponding limiting grooves 110. The fixing blocks 321 are fixed to the flange surface of the inlet flange 11 by screws.

[0033] like Figure 4 , Figure 6 As shown, the positioning assembly 34 may further include a positioning seat 341 with a central positioning hole 340 and multiple connecting segments 342 spaced apart and connected to the circumference of the positioning seat 341. Each connecting segment 342 is connected to a corresponding fixing rod 33. The central positioning holes 340 of the positioning seats 341 of the multiple sets of positioning assemblies 34 are sequentially connected to each other to form a centering and fixing channel.

[0034] The positioning seat 341 is also provided with at least one adjusting screw 343, which is radially inserted into the positioning seat 341, with the tail end of the adjusting screw 343 protruding from the central positioning hole 340. The adjusting screw 343 can move back and forth axially relative to the positioning seat 341 to adjust the length of the tail end within the central positioning hole 340, so as to press against or move away from the guide tube 40.

[0035] exist Figure 1 In the illustrated embodiment, there are four fixing rods 33. Correspondingly, as shown... Figures 4-6 As shown, the second base 32 includes four fixing blocks 321, and the positioning seat 341 has four connecting sections 342 circumferentially arranged. The four fixing rods 33 are distributed in a rectangular pattern and are located in four directions. One end of each fixing rod 33 is fixed to one of the fixing blocks 321, and the other end is fixed to the first base 31.

[0036] Understandably, the number of fixing rods 33 and positioning components 34 can be increased or decreased according to actual needs.

[0037] When assembling the centering fixture 30, the fixing rod 33 is first installed in the grooves of the first base 31 and the second base 32, and then welded to prevent deformation of the fixing rod 33 during welding. Each positioning component 34 is welded between the four fixing rods 33 through four connecting sections 342. The spacing between each positioning component 34 is set with reference to the spacing of the prototype fuel assembly grid.

[0038] After the guide tube 40 is installed in the centering fixture 30, the guide tube 40 is fixed by adjusting screws 343 around the locking positioning seat 341 in a manner that simulates the fixing of the prototype fuel assembly grid.

[0039] In the fuel cladding scouring experimental apparatus of the present invention, the guide tube 40 is centered and fixed within the centering and fixing fixture 30 by a centering and fixing method, as shown in the reference. Figures 4-7 The method for centering and fixing the guide tube 40 may include the following steps: S1. Place the centering fixing fixture 30 vertically, insert the guide tube 40 and initially fix it in the centering fixing channel of the centering fixing fixture 30; the first base 31 of the centering fixing fixture 30 faces upward.

[0040] Specifically, the axial installation position of the guide tube 40 is determined by the distance between the inlet and outlet ends of the guide tube 40 and the first base 31 and the second base 32, and the adjusting screws 343 of each positioning component 34 are pre-tightened to initially fix the guide tube 40.

[0041] S2. Arrange multiple hammer wires 200 at intervals along the circumference of the guide tube 40, and pass them from the bottom of the guide tube 40 into the centering and fixing channel from bottom to top. After the hammer wires 200 pass out of the centering and fixing channel, they are fixed to the hammer wire fixing fixture set above the guide tube 40.

[0042] Taking four plumb lines 200 as an example, the four plumb lines 200 are passed sequentially from bottom to top through each positioning component 34 from the bottom inlet end of the guide tube 40. It is important to ensure that the plumb lines 200 avoid the position of the adjusting screw 343. Then, the ends of the four plumb lines 200 are fixed at the top outlet end of the guide tube 40 using a plumb bob fixing fixture. Furthermore, to prevent the bottom hammers 210 from interfering with each other, the hammers 210 should be arranged axially offset from the guide tube 40.

[0043] S3. The hammers 210 of the multiple hammer lines 200 are staggered in the axial direction of the guide tube 40, so that the guide tube 40 and the lower end of the hammer lines 200 are suspended in the air.

[0044] Specifically, the second base 32 of the centering fixture 30 is supported by a support fixing component, so that the centering fixture 30 is erected and the lower ends of the hammer line 200 and the guide tube 40 are suspended in the air and do not contact the surrounding objects.

[0045] Supporting fasteners include regular components such as H-beam short sections.

[0046] S4. Adjust the bottom surface of the second base 32 of the centering fixture 30 with a standard feeler gauge to make the surface of the first base 31 of the centering fixture 30 horizontal, and confirm that the plumb line 200 hangs down naturally and the plumb bob is not interfered with.

[0047] S5. Check the plumb line 200 between the uppermost positioning component 34 in the centering fixture 30 and the plumb line fixing fixture. Adjust the adjusting screw 343 on the positioning component 34 so that the plumb line 200 fits against the outer wall of the guide tube 40, and then tighten the adjusting screw 343.

[0048] S6. Referring to step S5, adjust the adjusting screws 343 of each positioning component 34 from top to bottom so that the hammer line fits against the outer wall of the guide tube 40. Then tighten the adjusting screws 343 until the adjustment of all positioning components 34 is completed.

[0049] A second check is performed to ensure proper fit between the outer wall of the guide tube 40 and the hammer line 200. If misfitting is found, return to step S4 for readjustment. After confirming that everything is correct, remove the hammer line 200 and its fixing fixture. In summary, the centering adjustment and fixing of the guide tube 40 are complete.

[0050] The fuel cladding scouring experimental apparatus and its centering and fixing method of the present invention have low requirements for the workplace and auxiliary equipment: the centering process only requires ensuring that the centering and fixing fixture remains vertically stable and horizontal, without the need for other auxiliary equipment; In order to simultaneously meet the flushing test requirements of ATF-clad tubes of different specifications, such as Figure 8 As shown, the fuel cladding scouring experimental apparatus of the present invention also includes a sample fixing fixture 300 for suspending the experimental sample 100 within the guide tube 40. The sample fixing fixture 300 is designed with reference to the prototype fuel assembly upper pipe seat, featuring an outlet flange inner flow channel and simulating the prototype flow-blocking plug assembly support plate design. The sample fixing fixture 300 includes a strip-shaped fixing seat, which is fixed to the flange face of the outlet flange 21 via screw holes at both ends. The experimental sample 100 is installed at the center hole position of the sample fixing fixture 300 via a nut at the upper end. All fixing structures are threaded connections, facilitating disassembly and replacement.

[0051] In the application embodiment of the present invention, an experimental study on the erosion resistance of a type of ATF-clad tube was completed. Under long-term continuous erosion, the experimental device operated reliably without any abnormalities, the sample fixing fixture structure was stable, and the sample did not loosen. Vibration data of the sample after erosion and the outer wall of the guide tube during the entire erosion cycle were obtained, which strongly supported the evaluation of the erosion resistance of this type of ATF-clad tube and provided experimental support for the development of new ATF cladding materials.

[0052] In summary, the fuel cladding scouring experimental apparatus of the present invention has a simple overall structure, meets the operating conditions for scouring, and greatly reduces the experimental difficulty and cost while ensuring the rationality and reliability of the experimental method.

[0053] The device and centering and fixing method of the present invention are not only applicable to guide tubes, but can also be extended to installation scenarios of slender tubes with large length-to-diameter ratios of the same type that require high installation accuracy.

[0054] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A fuel cladding scouring experimental apparatus, characterized in that, This includes the inlet section, the outlet section, the centering and fixing fixtures of the simulated fuel assembly grid, and the slender guide tubes used to suspend the experimental samples. The inlet section and the outlet section are arranged at relative intervals. The centering fixing fixture is vertically connected between the inlet section and the outlet section. The centering fixing fixture is provided with a centering fixing channel. The guide tube is centered and fixed in the centering fixing channel and vertically connected between the inlet section and the outlet section. The guide tube is connected to the inlet channel of the inlet section and the outlet channel of the outlet section, respectively.

2. The fuel cladding scouring experimental apparatus according to claim 1, characterized in that, The centering and fixing fixture includes a first base, a second base, multiple fixing rods, and multiple sets of positioning components; The first base and the second base are arranged at intervals relative to each other. Multiple fixing rods are arranged in parallel and vertically connected between the first base and the second base. Multiple positioning components are located in the space enclosed by the multiple fixing rods, and are arranged at intervals along the axial direction of the fixing rods and connected between the multiple fixing rods.

3. The fuel cladding scouring experimental apparatus according to claim 2, characterized in that, The positioning component includes a positioning seat with a central positioning hole and multiple connecting segments arranged at intervals and connected to the circumference of the positioning seat; each connecting segment is connected to a corresponding fixing rod; the central positioning holes of the positioning seats of the multiple sets of positioning components are sequentially connected to each other to form the centering fixing channel.

4. The fuel cladding scouring experimental apparatus according to claim 3, characterized in that, The multiple fixing rods are four fixing rods; the positioning seat has four connecting sections circumferentially.

5. The fuel cladding scouring experimental apparatus according to claim 3, characterized in that, The positioning seat is also provided with at least one adjusting screw, which is radially inserted into the positioning seat, and the tail end of the adjusting screw protrudes into the central positioning hole; The adjusting screw can move back and forth axially relative to the positioning seat, adjusting the length of its tail end within the central positioning hole to press against or move away from the guide tube.

6. The fuel cladding scouring experimental apparatus according to claim 2, characterized in that, The first base is a circular ring structure; the second base includes multiple fixing blocks, which are spaced apart on the inlet section and avoid the bolts on the inlet section; one end of each fixing rod is fixed to a fixing block, and the other end is fixed to the first base.

7. The fuel cladding scouring experimental apparatus according to claim 1, characterized in that, The inlet section includes an inlet pipe section, an inlet flange disposed at at least one end of the inlet pipe section, and a first sealing flange disposed on the surface of the inlet flange; the first sealing flange is provided with a first central hole, which is connected to the central stepped through hole of the inlet flange; one end of the guide pipe passes through the first central hole and is inserted into and positioned in the central stepped through hole of the inlet flange.

8. The fuel cladding scouring experimental apparatus according to claim 1, characterized in that, The outlet section includes an outlet pipe section, an outlet flange disposed at at least one end of the outlet pipe section, and a second sealing flange disposed on the surface of the outlet flange; the second sealing flange is provided with a second central hole, which is connected to the central stepped through hole of the outlet flange; one end of the guide pipe passes through the second central hole and is inserted into and positioned in the central stepped through hole of the outlet flange.

9. The fuel cladding scouring experimental apparatus according to claim 8, characterized in that, The outlet section also includes a branch pipe radially connected to the outlet pipe section, and the outlet channel of the outlet section passes through the branch pipe.

10. A method for centering and fixing a guide tube, characterized in that, The guide tube in the fuel cladding scouring test apparatus according to any one of claims 1-9 is aligned and fixed within the alignment and fixing fixture; the guide tube alignment and fixing method includes the following steps: S1. Place the centering fixing fixture vertically, insert the guide tube and initially fix it in the centering fixing channel of the centering fixing fixture; the first base of the centering fixing fixture faces upward; S2. Arrange multiple hammer wires at intervals along the circumference of the guide tube, and pass them from the bottom of the guide tube into the centering and fixing channel from bottom to top. After the hammer wires pass through the centering and fixing channel, they are fixed to the hammer wire fixing fixture set above the guide tube. S3. The hammers of the multiple hammer lines are staggered in the axial direction of the guide tube, so that the lower ends of the guide tube and the hammer lines are suspended in the air; S4. Adjust the bottom surface of the second base of the centering fixture using a standard feeler gauge to make the surface of the first base of the centering fixture horizontal, and confirm that the plumb line hangs down naturally and the plumb bob does not interfere. S5. Check the plumb line between the uppermost positioning component and the plumb line fixing device in the centering fixing fixture, adjust the adjusting screw on the positioning component to make the plumb line fit against the outer wall of the guide tube, and then tighten the adjusting screw. S6. Adjust the adjusting screws of each positioning component from top to bottom in sequence so that the hammer line fits against the outer wall of the guide tube, and then tighten the adjusting screws until the adjustment of all positioning components is completed.

11. The method for centering and fixing the guide tube according to claim 10, characterized in that, In step S3, a support and fixing component is used to support and position the second base of the centering fixing fixture, so that the centering fixing fixture is erected and the lower ends of the hammer line and the guide tube are suspended in the air.

12. The method for centering and fixing the guide tube according to claim 11, characterized in that, The supporting fastener includes a short H-beam.

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