Multifunctional inspection rack for inspecting fuel element after irradiation

Abstract

The invention provides a multifunctional inspection rack for inspecting a fuel element after irradiation, and relates to a nuclear fuel element after-irradiation inspection technology, the rack comprises a base, a portal frame and a driving structure arranged on the base, a plurality of supporting structures used for supporting the fuel element, and a plurality of limiting structures arranged on the inspection rack. A to-be-detected channel for the fuel element to pass through is formed between the supporting structure and the limiting structure. A detection part is installed on the portal frame, and an annular detection area for a fuel element to penetrate through is arranged in the portal frame. A first avoiding structure is arranged on the supporting structure, and a second avoiding structure is arranged on the limiting structure. When the portal frame moves in the axial direction of the fuel element, the supporting structure can be driven to move downwards and the limiting structure can be driven to move in the radial direction by extruding the first avoiding structure and the second avoiding structure, so that the shielded fuel element area is exposed in the detection range of the detection component, and continuous and non-blind area detection of the whole length of the fuel element is achieved. The problem of detection blind areas caused by shielding of supporting and limiting structures in the prior art is effectively solved.

Description

Technical Field

[0001] This invention relates to the field of post-irradiation inspection technology for nuclear fuel elements, and more specifically, to a multifunctional inspection stand for post-irradiation inspection of fuel elements. Background Technology

[0002] After nuclear reactor fuel elements have endured harsh irradiation, high temperature, and high pressure environments within the reactor, their performance and safety status must be assessed through thorough post-irradiation inspections (PIE). These inspections are crucial for verifying fuel design, understanding fuel behavior, and ensuring nuclear safety. Among the many inspection items, non-destructive testing (such as eddy current testing) of the fuel element cladding tubes, examining for appearance, defects, and oxide film thickness, is a fundamental and important step.

[0003] Currently, automated non-destructive testing of irradiated fuel elements typically requires a dedicated inspection bench within a hot chamber. A traditional inspection bench usually includes a base, a support and limiting mechanism for supporting and guiding the fuel element, and a test probe (such as an eddy current probe) that can move along the element's axial direction.

[0004] However, existing inspection bench designs have significant limitations. To support and precisely position fuel elements, several support blocks and limiting blocks must be installed on the bench. These necessary structural components physically obscure portions of the fuel element's surface area. When the detection probe moves to these support / limiting areas, it cannot effectively scan the obscured element segments, creating "blind spots" in the detection data. This results in the inability to obtain continuous and complete data across the entire surface of the fuel element, leaving uncertainties in fuel performance analysis and posing potential safety hazards. Summary of the Invention

[0005] The purpose of this invention is to provide a multifunctional inspection stand for post-irradiation inspection of fuel elements, which addresses the shortcomings of existing technologies and solves the problems mentioned in the background.

[0006] The technical solution of this invention is implemented as follows: The invention provides a multifunctional inspection stand for post-irradiation inspection of fuel elements, including a base and a gantry frame disposed on the side wall of the base; A drive structure, mounted on the base, is used to drive the gantry frame to move along the extension direction of the base; Several support structures are installed on the sidewalls of the base along its extension direction to support the fuel element; The testing frame is mounted on the side wall of the base; Several limiting structures are set on the testing frame, and the limiting structures and the supporting structure form a testing channel for the movement of the fuel element; The detection component is installed on the side wall of the gantry facing the fuel element, and the fuel element passes through the annular detection area inside the detection component; The supporting structure is provided with a first clearance structure, and the limiting structure is provided with a second clearance structure. When the gantry is driven by the drive structure to move the detection component along the axial direction of the fuel element, the gantry squeezes the first clearance structure, causing the support structure to move downward in the vertical direction, and at the same time squeezes the second clearance structure, causing the limiting structure to move radially along the fuel element, so that the detection component can pass through the fuel element area blocked by the support structure or the limiting structure and expose the area to the detection range of the detection component.

[0007] In some technical solutions of the present invention, the support structure includes a first mounting bracket mounted on a base, a clearance seat disposed on the side wall of the first mounting bracket, and a support frame disposed on the clearance seat; two rollers are rotatably disposed on the side wall of the support frame, the rotation direction of the rollers is tangent to the axial direction of the fuel element, and a support channel for supporting the fuel element is formed between the two rollers; the first clearance structure is connected between the clearance seat and the first mounting bracket, and is used to drive the support structure to reciprocate in the vertical direction.

[0008] In some technical solutions of the present invention, the first clearance structure includes a shaft, a sliding sleeve, and a buffer spring; the shaft is mounted on a first mounting bracket; the sliding sleeve is sleeved on the outer side wall of the shaft and connected to the clearance seat; two buffer springs are sleeved on the shaft and located on both sides of the sliding sleeve, with their free ends abutting against the corresponding side walls of the first mounting bracket; the clearance seat has first inclined surfaces on both sides, and the first inclined surfaces and the top of the clearance seat have first guide grooves opened in the horizontal direction, with the angle between the reverse extension line of the first inclined surface and the top edge of the clearance seat being an obtuse angle; a limiting block is provided on the inner side wall of the gantry frame for cooperating with the first inclined surface.

[0009] In some technical solutions of the present invention, two first guide rods are also included, the first guide rods being installed inside the first mounting bracket; a guide seat is connected to the clearance seat, and the guide seat is sleeved on the outside of the first guide rod.

[0010] In some technical solutions of the present invention, the detection component includes a positioning frame and a detection seat; the positioning frame is mounted on a gantry frame; the detection seat is detachably disposed at the end of the positioning frame, and an annular detection channel is provided on its side wall, and a plurality of eddy current detection probes are arranged equidistantly along the circumference of the annular detection channel inside the detection seat; the positioning frame is provided with an adjustment structure for driving the detection seat to make circular motion around the fuel element.

[0011] In some technical solutions of the present invention, the positioning structure includes a mounting base, a guide wheel, a mounting sleeve, and a transmission assembly; the mounting base is disposed on the side wall of the positioning frame; the guide wheel is rotatably disposed within the mounting base; a plurality of inclined guide grooves are equidistantly provided on the side wall of the annular detection channel for cooperating with the guide wheel, and a portion of the tooth key on the guide wheel is embedded in the guide groove; the mounting is disposed on the side wall of the positioning frame and sleeved on the outside of the detection base; the positioning frame is provided with a transmission structure for driving the guide wheel to rotate.

[0012] In some technical solutions of the present invention, the transmission component includes a traveling wheel, a first transmission wheel is mounted on the axle of the traveling wheel, and a second transmission wheel is disposed on the outer wall of the mounting sleeve. The first transmission wheel and the second transmission wheel are connected by belt drive.

[0013] In some technical solutions of the present invention, a second guide groove is provided on the side wall of the second mounting bracket along the vertical direction, a guide block is slidably disposed in the second guide groove, and the guide block is connected to the adjustment structure; a limiting spring is provided in the second guide groove, and the limiting spring is connected to the guide block.

[0014] In some technical solutions of the present invention, the limiting structure includes two second mounting brackets arranged in pairs; a second guide rod is installed on the opposite sidewalls of the two second mounting brackets, the second guide rod passes through the detection frame and extends outward, and a return spring is sleeved on the outer side of the second guide rod; an adjustment bracket is provided on the sidewall of each second mounting bracket, and a limiting roller is rotatably provided at the end of the adjustment bracket, the limiting roller abutting against the outer sidewall of the fuel element.

[0015] In some technical solutions of the present invention, the second avoidance structure includes two supporting blocks arranged in pairs, the cross-section of which is an isosceles trapezoid; the two supporting blocks are respectively installed on both sides of the positioning frame; when the driving structure drives the positioning frame to move along the axis of the fuel element, the inclined surface of the supporting block presses against the second mounting bracket of the limiting structure, forcing the two second mounting brackets to move in opposite directions along the radial direction of the fuel element, compressing the return spring, and causing the limiting roller to disengage from the fuel element, thereby exposing the originally blocked fuel element area to the annular detection channel so that the detection seat can pass through and detect the area.

[0016] Compared to existing technologies, this invention has at least the following advantages or beneficial effects: When the gantry moves along the axial direction of the fuel element, its body compresses the first and second avoidance structures, which respectively drive the support structure to move downward and the limiting structure to move radially. This exposes the obscured fuel element area to the detection range of the detection component, enabling continuous, blind-spot-free detection of the entire length of the fuel element. This effectively solves the problem of blind spots caused by the obstruction of the support and limiting structures in existing technologies. Furthermore, the movement of the gantry itself serves as the power source to trigger the avoidance action, eliminating the need for a separate drive motor or cylinder for each avoidance point. This simplifies the structure, reduces manufacturing costs and maintenance complexity, and improves reliability under irradiation conditions. Attached Figure Description

[0017] Figure 1 This is a front view schematic diagram of the inspection stand in this invention.

[0018] Figure 2 This is a schematic diagram of the installation structure of the avoidance seat in this invention.

[0019] Figure 3 This is a schematic diagram of the installation structure of the first avoidance structure in this invention.

[0020] Figure 4 This is a side view of the installation structure of the avoidance seat in this invention.

[0021] Figure 5 This is a schematic diagram of the installation structure of the limiting structure in this invention.

[0022] Figure 6 This is a schematic diagram of the installation structure of the second avoidance structure in this invention.

[0023] Figure 7 This is a schematic diagram of the installation structure of the support block in this invention.

[0024] Figure 8 This is a three-dimensional structural diagram of the adjustment structure in this invention.

[0025] Figure 9 This is a schematic diagram of the internal structure of the adjustment structure in this invention.

[0026] Figure 10 This is a side view of the adjustment structure in this invention.

[0027] Reference numerals: 1. Base; 2. Gantry frame; 201. Limiting block; 3. Drive structure; 4. Support structure; 401. First mounting bracket; 402. Clearance seat; 406. First inclined surface; 403. Support frame; 404. Roller; 405. First guide groove; 5. Detection frame; 6. Limiting structure; 601. Second mounting bracket; 602. First guide rod; 603. Return spring; 604. Adjustment frame; 605. Limiting roller; 7. Detection component; 701. Positioning frame; 702. Detection seat; 703. Annular detection channel; 7 04. Eddy current detection probe; 705. Guide groove; 8. First clearance structure; 801. Shaft; 802. Sliding sleeve; 803. Buffer spring; 9. Second clearance structure; 901. Support block; 10. Adjustment structure; 1001. Mounting base; 1002. Guide wheel; 1003. Mounting sleeve; 1004. Traveling wheel; 1005. First transmission wheel; 1006. Second transmission wheel; 1007. Belt; 11. Second guide rod; 12. Guide seat; 13. Second guide groove; 14. Guide block; 15. Limiting spring; 16. Fuel element. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0029] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0030] Example This invention provides a multifunctional inspection stand for post-irradiation inspection of fuel elements, such as... Figures 1-10 As shown, it includes a base 1, which is a steel platform structure arranged along the extension direction of the fuel element 16, to ensure that the fuel element 16 is tested on the same horizontal plane.

[0031] A gantry 2 is mounted on the side wall of the base 1. A drive structure 3 is provided on the base 1 to guide the gantry 2 along its extension direction. The drive structure 3 is existing technology, such as a screw drive structure. The gantry 2 is also conventional technology. The drive structure 3 can drive the gantry 2 to move at a constant speed along the extension direction of the base 1, ensuring the accuracy of the detection structure and preventing omissions of any positions of the fuel element 16 to be tested, thus improving the continuity of the detection results. Several support structures 4 for supporting the fuel element 16 are installed on the side wall of the base 1 along its extension direction. Each support structure 4 includes at least two fixed support wheels arranged in the same horizontal direction, and a strip-shaped groove is vertically formed on the side wall of the mounting base 1. The circumference of the fixed support wheels is fixed to the mounting base 1 by nuts, and the horizontal height of the fixed support wheels can be adjusted synchronously according to actual conditions.

[0032] A testing frame 5 is mounted on the side wall of the mounting base 1. The testing frame 5 is provided with several limiting structures 6, including at least two movable support wheels arranged in the same horizontal direction, with the two movable support wheels positioned between two fixed support wheels. There is a testing channel between the limiting structure 6 and the support structure 4 for the movement of the fuel element 16.

[0033] A detection component 7 for detecting the fuel element 16 is installed on the side wall of the gantry 2 opposite to the fuel element 16. The fuel element 16 extends outward after passing through the annular area inside the detection component 7.

[0034] The support structure 4 is equipped with a first clearance structure 8, and the limiting structure 6 is equipped with a second clearance structure 9. When the gantry 2 drives the detection component 7 to move axially along the fuel element 16, the first clearance structure 8, under the compression of the gantry 2, drives the support structure 4 to move vertically downward, and the second clearance structure 9, under the compression of the gantry 2, drives the limiting structure 6 to move radially along the fuel element 16; this allows the detection component 7 to pass through the area of ​​the fuel element 16 that was blocked by the support structure 4 or the limiting structure 6, and exposes the blocked area of ​​the fuel element 16 to the detection area of ​​the detection component 7. The fuel element 16 is 4 meters long. In actual operation, the drive structure 3 is activated, causing the gantry 2 to drive the detection component 7 to move along the axial direction of the fuel element 16. The gantry 2 squeezes the first clearance structure 8 and the second clearance structure 9, forcing the support structure 4 to move downward and the limiting structure 6 to move radially, temporarily making room so that the obscured area of ​​the fuel element 16 is exposed to the scanning range of the detection component 7. This achieves continuous and blind-spot-free detection of the entire length of the fuel element 16, avoids the obstruction of the detection results by the support and limiting components, and improves the integrity and accuracy of the detection data.

[0035] In some technical solutions of the present invention, the support structure 4 includes a first mounting bracket 401 mounted on the base 1. A clearance seat 402 is provided on the side wall of the first mounting bracket 401, and a support frame 403 is provided on the clearance seat 402. Two rollers 404, which rotatably contact the fuel element 16, are provided on the side wall of the support frame 403. The rotation direction of the rollers 404 is tangent to the axial direction of the fuel element 16. A support channel for supporting the fuel element 16 is provided between the two rollers 404. A first clearance structure 8 is mounted on the clearance seat 402 and the first mounting bracket 401 to drive the support structure 4 to reciprocate in the vertical direction. The support structure 4 uses a roller 404 design, whose rotation direction is tangent to the axis of the fuel element 16. This allows the fuel element 16 to be moved or rotated with low resistance in the axial direction while supporting the fuel element 16, facilitating position adjustment. When the clearance seat 402 is in its initial state or when it is not in motion, the fuel element 16 is placed on the support channel formed by the two rollers 404 of the moving support frame 403. When testing is required, the clearance seat 402 moves down, the moving support frame 403 descends accordingly, and the rollers 404 disengage from the fuel element 16. The first clearance structure 8 acts as an actuator, converting the lateral compressive force of the gantry 2 into the vertical movement of the support structure 4. The rotating rollers 404 support reduces the frictional resistance of the fuel element 16 during movement or testing, preventing scratches on the element surface.

[0036] In some technical solutions of the present invention, the first clearance structure 8 includes a shaft 801 installed between two first guide rods 602. The shaft 801 is connected to the first mounting bracket 401. A sliding sleeve 802 is sleeved on the outer side wall of the shaft 801. The sliding sleeve 802 is connected to the clearance seat 402. Two buffer springs 803 are sleeved on the outer side wall of the shaft 801, respectively located on both sides of the sliding sleeve 802. The free ends of the two buffer springs 803 abut against the side wall of the first mounting bracket 401 located on the same side. A first inclined surface 406 is provided on both sides of the clearance seat 402. A first guide groove 405 is opened in the horizontal direction on the first inclined surface 406 and the top of the clearance seat 402. The angle between the reverse extension line of the first inclined surface 406 and the top edge of the clearance seat 402 is an obtuse angle. A limiting block 201 is provided on the inner side wall of the gantry frame 2. Two first guide rods 602 provide a precise linear motion track for the avoidance seat 402, restricting all unnecessary degrees of freedom (such as left and right swaying and twisting), retaining only the vertical degree of freedom. Guide seats 12, located on the avoidance seat 402 and fitted onto the two first guide rods 602 within the first mounting bracket 401, allow the avoidance seat 402 to slide strictly vertically up and down along the trajectory defined by the first guide rods 602. The spring, acting as an energy storage element, absorbs and releases energy through its deformation, achieving deceleration and buffering. The shaft 801 provides a reference for the installation and movement of the spring and the sliding sleeve 802. When the avoidance seat 402 descends along the first guide rod 602, the sliding sleeve 802 connected to it slides along the shaft 801, compressing the buffer spring 803 (the spring located below the avoidance seat 402) on one side. The spring is compressed, absorbing downward kinetic energy. When a reset is required, the compressed spring releases energy to assist the avoidance seat 402 in rising, while the spring on the other side (the spring located above the avoidance seat 402) acts as a buffer at the end of the rising stroke.

[0037] In some technical solutions of the present invention, two first guide rods 602 are installed within the first mounting bracket 401, and a guide seat 12 connected to the avoidance seat 402 is sleeved on the outer side of the first guide rod 602. Through the sliding engagement of the first guide rod 602 and the guide seat 12, precise guidance is provided for the vertical reciprocating movement of the avoidance seat 402, which is sleeved on the first guide rod 602 via the guide seat 12. When an avoidance action occurs, the guide seat 12 slides along the first guide rod 602 to prevent it from jamming or shifting during movement.

[0038] In some technical solutions of the present invention, the detection structure includes a positioning frame 701 mounted on a gantry 2. A detection seat 702 is detachably mounted on the end of the positioning frame 701. An annular detection channel 703 is formed on the side wall of the detection seat 702. A plurality of eddy current detection structures are equidistantly arranged in the circumference of the circle containing the annular detection channel 703 within the detection seat 702. An adjustment structure 10 is provided on the positioning frame 701 for driving the detection seat 702 to perform circular motion. By driving the detection seat 702 to rotate through the adjustment structure 10, the eddy current detection structures fixed in the circumference of the detection seat 702 rotate at a uniform speed, enabling the eddy current detection structures to scan the entire circumferential surface of the fuel element 16, achieving omnidirectional detection. The multiple eddy current detection probes 704 integrated on the detection seat 702 can measure the fuel element 16 at different positions in the circumferential direction without the need for manual adjustment of the detection angle of the eddy current detection probes 704, thus improving detection efficiency.

[0039] In some technical solutions of the present invention, the positioning structure 10 includes a mounting base 1001, a guide wheel 1002, a mounting sleeve 1003, and a transmission assembly; the mounting base 1001 is disposed on the side wall of the positioning frame 701; the guide wheel 1002 is rotatably disposed within the mounting base 1001; a plurality of inclined guide grooves 705 are equidistantly provided on the side wall of the annular detection channel 703 for cooperating with the guide wheel 1002, and the teeth on the guide wheel 1002 are partially embedded in the guide grooves 705; the positioning structure 10 is mounted on the side wall of the positioning frame 701 and sleeved on the outside of the detection base 702; the positioning frame 701 is provided with a transmission structure for driving the guide wheel 1002 to rotate.

[0040] In some technical solutions of this invention, the transmission assembly includes a traveling wheel 1004, a first transmission wheel 1005 mounted on the shaft 801 of the traveling wheel 1004, and a second transmission wheel 1006 disposed on the outer wall of the mounting sleeve 1003. The first transmission wheel 1005 and the second transmission wheel 1006 are connected by a belt 1007. Power is provided by the belt 1007 gear transmission, and the rotational motion is converted into the required circumferential scanning motion through the guide wheel 1002-sloping groove mechanism (which can be regarded as a simple cam mechanism). The adjustment motor is started to drive the gear to drive the mounting cylinder and the detection seat 702 to rotate through the belt 1007. The guide wheel 1002 cooperates with the inclined guide groove 705 on the detection seat 702 to convert the motor-driven rotational motion into a smooth circumferential motion of the detection seat 702. This realizes the automatic rotational scanning of the detection seat 702. The cooperation between the inclined groove and the guide wheel 1002 helps to ensure the smoothness and accuracy of the movement process.

[0041] In some technical solutions of the present invention, a second guide groove 13 is provided vertically on the side wall of the second mounting bracket 601. A guide block 14 connected to the adjusting bracket 604 is slidably disposed in the second guide groove 13, and a limiting spring 15 connected to the guide block 14 is disposed in the second guide groove 13. The adjusting structure 10 provides a flexible mounting base, giving it a certain vertical buffering capacity. The adjusting bracket 604 can move slightly vertically via the guide block 14, and the limiting spring 15, in conjunction with the hydraulic push rod, supports the guide block 14 to prevent it from axially moving.

[0042] In some technical solutions of the present invention, the limiting structure 6 includes two paired second mounting brackets 601. Each of the two second mounting brackets 601 has a second guide rod 11 mounted on its opposite sidewall. The second guide rod 11 extends outward through the detection frame 5 located on the same side. A return spring 603 is sleeved on the outer side of the second guide rod 11. Each of the second mounting brackets 601 has an adjusting bracket 604 on its sidewall. The end of each adjusting bracket 604 is rotatably equipped with a limiting roller 605 that abuts against the outer side of the fuel element 16. Normally closed limiting is achieved using spring force. When avoidance is required, external mechanical force overcomes the spring force to open the channel. Under the action of the return spring 603, the limiting rollers 605 on the two second mounting brackets 601 normally clamp the fuel element 16 from both sides, serving a centering and limiting function. When avoidance is required, external force forces the two second mounting brackets 601 to move to both sides along the second guide rod 11, compressing the return spring 603 and causing the limiting rollers 605 to disengage from the element.

[0043] In some technical solutions of the present invention, the second avoidance structure 9 includes two pairs of support blocks 901. The cross-section of each support block 901 is an isosceles trapezoid. The two support blocks 901 are respectively installed on both sides of the positioning frame 701. When the driving structure 3 drives the positioning frame 701 to move along the axis of the fuel element 16, the support blocks 901 on the positioning frame 701 force the two second mounting brackets 601 in the limiting structure 6 to move radially along the fuel element 16 and gradually disengage from the fuel element 16, exposing a portion of the fuel element 16 to the detection channel. This allows the detection seat 702 to pass between the two limiting rollers 605 to measure the oxide film on the side wall of the fuel element 16. When the positioning frame 701 with the detection seat 702 installed moves, the isosceles trapezoidal support blocks 901 on both sides will contact the limiting structure 6. As the movement continues, the inclined surface of the support block 901 presses against the limiting structure 6, forcing the two second mounting brackets 601 to overcome the elastic force of the return spring 603 and move radially outward, thereby causing the limiting roller 605 to disengage from the fuel element 16, exposing the obscured area for the detection seat 702 to pass through and detect. Utilizing the wedging effect of the isosceles trapezoidal inclined surface, the axial movement of the positioning frame 701 is converted into the radial opening movement of the limiting structure 6.

[0044] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A multifunctional inspection stand for post-irradiation inspection of fuel elements, characterized in that, Base (1); Gantry (2), set on the side wall of base (1); The drive structure (3) is set on the base (1) and is used to drive the gantry (2) to move along the extension direction of the base (1); Several support structures (4) are installed on the side wall of the base (1) along the extension direction of the base (1) to support the fuel element (16). The testing frame (5) is installed on the side wall of the base (1); Several limiting structures (6) are set on the testing frame (5), and the limiting structures (6) and the supporting structure (4) form a testing channel for the movement of the fuel element (16); The detection component (7) is installed on the side wall of the gantry (2) facing the fuel element (16), and the fuel element (16) passes through the annular detection area inside the detection component (7); Among them, the support structure (4) is provided with a first avoidance structure (8), and the limiting structure (6) is provided with a second avoidance structure (9). When the gantry (2) drives the detection component (7) to move along the axial direction of the fuel element (16) under the drive of the drive structure (3), the gantry (2) squeezes the first clearance structure (8) to drive the support structure (4) to move downward in the vertical direction, or squeezes the second clearance structure (9) to drive the limiting structure (6) to move radially along the fuel element (16), so that the detection component (7) can pass through the area of ​​the fuel element (16) blocked by the support structure (4) or the limiting structure (6) and expose the area to the detection range of the detection component (7).

2. A multifunctional inspection stand for post-irradiation inspection of fuel elements according to claim 1, characterized in that, The support structure (4) includes a first mounting bracket (401) mounted on the base (1), a clearance seat (402) disposed on the side wall of the first mounting bracket (401), and a support frame (403) disposed on the clearance seat (402); two rollers (404) are rotatably disposed on the side wall of the support frame (403), the rotation direction of the rollers (404) is tangential to the axial direction of the fuel element (16), and a support channel for supporting the fuel element (16) is formed between the two rollers (404); the first clearance structure (8) is connected between the clearance seat (402) and the first mounting bracket (401) and is used to drive the support structure (4) to reciprocate in the vertical direction.

3. A multifunctional inspection stand for post-irradiation inspection of fuel elements according to claim 2, characterized in that, The first clearance structure (8) includes a shaft (801), a sliding sleeve (802), and a buffer spring (803); the shaft (801) is mounted on the first mounting bracket (401); the sliding sleeve (802) is sleeved on the outer side wall of the shaft (801) and connected to the clearance seat (402); two buffer springs (803) are sleeved on the shaft (801) and located on both sides of the sliding sleeve (802), with their free ends connected to the first mounting bracket respectively. The corresponding side wall of (401) abuts; the two sides of the relief seat (402) are provided with a first inclined surface (406), and the top of the first inclined surface (406) and the relief seat (402) are provided with a first guide groove (405) in the horizontal direction. The angle between the reverse extension line of the first inclined surface (406) and the top edge of the relief seat (402) is an obtuse angle; the inner side wall of the gantry frame (2) is provided with a limiting block (201) for cooperating with the first inclined surface (406).

4. A multifunctional inspection stand for post-irradiation inspection of fuel elements according to claim 2 or 3, characterized in that, It also includes two first guide rods (602), which are installed inside the first mounting bracket (401); a guide seat (12) is connected to the clearance seat (402), and the guide seat (12) is sleeved on the outside of the first guide rod (602).

5. A multifunctional inspection stand for post-irradiation inspection of fuel elements according to claim 1, characterized in that, The detection component (7) includes a positioning frame (701) and a detection seat (702); the positioning frame (701) is mounted on the gantry (2); the detection seat (702) is detachably set at the end of the positioning frame (701), and an annular detection channel (703) is opened on its side wall. Several eddy current detection probes (704) are arranged equidistantly along the circumference of the annular detection channel (703) inside the detection seat (702); the positioning frame (701) is provided with an adjustment structure (10) for driving the detection seat (702) to make a circular motion around the fuel element (16).

6. A multifunctional inspection stand for post-irradiation inspection of fuel elements according to claim 5, characterized in that, The adjustment structure (10) includes a mounting base (1001), a guide wheel (1002), a mounting sleeve (1003), and a transmission assembly; the mounting base (1001) is set on the side wall of the positioning frame (701); the guide wheel (1002) is rotatably set in the mounting base (1001); a number of inclined guide grooves (705) are equidistantly opened on the side wall of the annular detection channel (703) for cooperating with the guide wheel (1002), and the teeth on the guide wheel (1002) are partially embedded in the guide grooves (705); it is installed on the side wall of the positioning frame (701) and sleeved on the outside of the detection base (702); the positioning frame (701) is provided with a transmission structure for driving the guide wheel (1002) to rotate.

7. A multifunctional inspection stand for post-irradiation inspection of fuel elements according to claim 6, characterized in that, The transmission assembly includes a traveling wheel (1004), a first transmission wheel (1005) mounted on the shaft (801) of the traveling wheel (1004), and a second transmission wheel (1006) disposed on the outer side wall of the mounting sleeve (1003). The first transmission wheel (1005) and the second transmission wheel (1006) are connected by a belt (1007).

8. A multifunctional inspection stand for post-irradiation inspection of fuel elements according to claim 5 or 6, characterized in that, The limiting structure (6) includes two second mounting brackets (601) arranged in pairs; a second guide rod (11) is installed on the opposite side wall of each of the two second mounting brackets (601), the second guide rod (11) passes through the testing frame (5) and extends outward, and a return spring (603) is sleeved on the outer side of the second guide rod (11); an adjustment frame (604) is provided on the side wall of each second mounting bracket (601), and a limiting roller (605) is rotatably provided at the end of the adjustment frame (604), the limiting roller (605) abuts against the outer side wall of the fuel element (16).

9. A multifunctional inspection stand for post-irradiation inspection of fuel elements according to claim 8, characterized in that, The second mounting bracket (601) has a second guide groove (13) vertically opened on the side wall. A guide block (14) is slidably arranged in the second guide groove (13). The guide block (14) is connected to the adjustment structure (10). A limit spring (15) is provided in the second guide groove (13). The limit spring (15) is connected to the guide block (14).

10. A multifunctional inspection stand for post-irradiation inspection of fuel elements according to claim 9, characterized in that, The second avoidance structure (9) includes two pairs of support blocks (901), the cross-section of which is an isosceles trapezoid. The two support blocks (901) are respectively installed on both sides of the positioning frame (701). When the drive structure (3) drives the positioning frame (701) to move along the axis of the fuel element (16), the inclined surface of the support block (901) presses against the second mounting bracket (601) of the limiting structure (6), forcing the two second mounting brackets (601) to move in opposite directions along the radial direction of the fuel element (16), compressing the reset spring (603), and causing the limiting roller (605) to disengage from the fuel element (16), thereby exposing the originally blocked area of ​​the fuel element (16) to the annular detection channel (703) so that the detection seat (702) can pass through and detect the area.

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