An irradiated fuel assembly lattice oxide film detection device

Abstract

The application provides an irradiated fuel assembly grid oxide film detection device, relates to nuclear power fuel pool edge detection technology, and specifically discloses a mounting base, a guide rail frame, a mounting frame, a position adjusting structure, a probe frame and a probe structure. The mounting frame is provided with a position adjusting seat and a driving structure, the two are made close to or away from each other through a sliding connection mechanism, and self-adaptive coating detection of the grid oxide film surface is realized. The position adjusting structure controls the axial movement of the mounting frame to cover all the to-be-detected areas. The driving structure converts the linear motion of the position adjusting seat into the radial motion of the probe frame, so that the probe always keeps in close contact with the grid oxide film surface, and the probe structure can contact or separate from the grid oxide film surface to realize scanning detection.

Description

Technical Field

[0001] This invention relates to the field of nuclear power fuel pool edge detection technology, and more specifically, to a device for detecting oxide film on fuel assembly grids after irradiation. Background Technology

[0002] After the fuel assembly is in operation in the reactor, the thickness of the oxide film on the surface of the assembly material is a key parameter for judging the corrosion performance of the fuel assembly in the reactor. Among them, the fuel assembly grid is the skeleton structural component of the assembly, which is related to the strength and structural performance of the assembly. The corrosion performance seriously affects the operating performance of the fuel assembly. During the operation of the grid, it will corrode and generate an oxide film, so the detection of the grid oxide film thickness is particularly important.

[0003] Currently, the oxide film of fuel assemblies is mainly measured by using eddy current point probes to measure the surface of the outermost fuel rods through the lift-off effect. Existing grid oxide film eddy current detection suffers from problems such as uneven grid surface, probe size that is too large to detect the oxide film position on the grid surface, difficulty in fitting the oxide film detection probe to the grid surface, difficulty in ensuring the posture, poor detection accuracy, unstable measurement and low detection efficiency caused by the temperature of the assembly grid surface. Summary of the Invention

[0004] The purpose of this invention is to provide a device for detecting oxide film on fuel assembly grids after irradiation, which addresses the shortcomings of existing technologies and solves the problems mentioned in the background.

[0005] The technical solution of this invention is implemented as follows: The present invention provides a device for detecting oxide film on fuel assembly grid after irradiation, including a mounting base, a guide rail frame provided on the side wall of the mounting base, a mounting frame slidably mounted on the guide rail frame, and an adjustment structure provided on the guide rail frame for driving the mounting frame to move back and forth along the extension direction of the guide rail frame. The mounting bracket has two probe holders in pairs, and probe structures are installed on the opposite side walls of the two probe holders. The mounting bracket is equipped with an adjustment seat, and both probe holders are slidably connected to the adjustment seat. The mounting bracket is provided with a drive structure for driving the adjustment seat to reciprocate along the extension direction of the guide rail. When the adjustment seat reciprocates along the extension direction of the guide rail, the probe holders slidably connected to the adjustment seat move closer to each other.

[0006] In some technical solutions of the present invention, the adjustment structure includes a first guide rail mounted on a guide rail frame, a first guide seat slidably connected to the first guide rail mounted on a mounting frame, a lead screw rotatably mounted on a mounting base, a displacement seat driven by the lead screw at the bottom of the mounting frame, and a drive motor driven by the lead screw on the mounting base.

[0007] In some technical solutions of this invention, the probe structure includes a mounting port at the end of the probe holder, a wear-resistant slider slidably disposed within the mounting port, a mounting hole being formed on the side wall of the wear-resistant slider facing the bottom of the mounting hole, a coil fixing seat being disposed within the mounting hole, a detection coil being disposed on the outer side wall of the coil fixing seat, and a pressure plate being disposed within the mounting port for connection to the probe holder, the pressure plate being detachably connected to the probe holder by screws. The pressure plate is provided with two springs that respectively abut against the wear-resistant slider, and a portion of the springs is embedded within the wear-resistant slider.

[0008] In some technical solutions of the present invention, the driving structure includes two connecting seats arranged in pairs. Each connecting seat has two inclined grooves on its side wall. The reverse extension lines of the two inclined grooves on the side away from the probe structure intersect at an acute angle. The side wall of the adjusting seat is provided with two limiting posts. The two limiting posts are slidably arranged in their corresponding inclined grooves. The side wall of the mounting frame is provided with a guide structure for guiding the two probe frames to move towards each other. The mounting frame is provided with a pushing structure for pushing the adjusting seat to reciprocate.

[0009] In some technical solutions of the present invention, the guide structure includes a second guide rail arranged along the width direction of the mounting frame, and a second guide seat is provided on the probe frame, the second guide seat being slidably connected to the second guide rail.

[0010] In some technical solutions of the present invention, a third guide rail is also provided along the extension direction of the mounting frame. The third guide rail is mounted on the side wall of the mounting frame, and a third guide seat is provided on the side wall of the displacement seat. The third guide seat is slidably connected to the third guide rail.

[0011] In some technical solutions of the present invention, the pushing structure includes a push rod structure mounted on the mounting bracket, and the telescopic end of the push rod structure is connected to the side wall of the displacement seat.

[0012] In some technical solutions of the present invention, a fixing frame is provided on the side wall of the mounting frame, a buffer column is inserted through the side wall of the fixing frame, a buffer spring connected to the fixing frame is sleeved on the outer side wall of the buffer column, and a buffer pad is provided at the end of the buffer column opposite to the displacement seat.

[0013] In some technical solutions of the present invention, the side wall of the mounting base is equipped with a limit frame, and two calibration frames are provided in pairs on the side wall of the limit frame. The calibration frames are provided with a mounting groove on the side wall opposite to the probe frame, and a plurality of calibration blocks are provided at equal intervals along the extension direction of the probe frame in the mounting groove.

[0014] In some technical solutions of the present invention, an electric push rod is installed inside the mounting base, a limit frame is provided on the telescopic end of the electric push rod, a limit wheel is rotatably provided at the end of the limit frame, and a stop block is provided on the side wall of the mounting frame to abut against the limit frame.

[0015] Compared with the prior art, the present invention has at least the following advantages or beneficial effects: When the two probe holders symmetrically arranged on the mounting frame move along the guide rail under the drive of the adjusting seat, they can move closer or further apart, enabling adaptive coating detection of the fuel rod surface; the adjusting structure controls the axial movement of the mounting frame to cover the entire area to be measured, and the driving structure converts the linear movement of the adjusting seat into the radial movement of the probe holder, ensuring that the probe structure always remains in contact with the fuel rod surface, thereby achieving contact or detachment scanning detection; the probe is installed in the wear-resistant slider through a coil fixing seat, and during detection, the spring pushes the wear-resistant slider to press tightly against the fuel rod surface. When encountering protrusions or depressions, it can slide along the mounting opening for compensation, improving measurement accuracy; the spring buffers the wear-resistant slider, avoiding hard collisions between the probe and the fuel rod, protecting the brittle fuel rod surface; the wear-resistant slider reduces direct wear on the probe and ensures constant pressure when in contact with the grid oxide film, ensuring the stability of the detection signal and improving the accuracy of oxide film thickness measurement. Attached Figure Description

[0016] Figure 1 This is a first-view three-dimensional structural diagram of the grid oxide film detection device of the present invention.

[0017] Figure 2 This is a second-view three-dimensional structural diagram of the grid oxide film detection device of the present invention.

[0018] Figure 3 This is a schematic diagram of the internal structure of the grid oxide film detection device in this invention.

[0019] Figure 4 This is a half-sectional schematic diagram of the grid oxide film detection device of the present invention.

[0020] Figure 5 This is a schematic diagram of the installation structure of the pushing structure in this invention.

[0021] Figure 6 This is a cross-sectional view of the probe holder and probe structure in this invention.

[0022] Reference numerals: 1-Mounting base; 2-Guide rail bracket; 3-Mounting bracket; 4-Adjusting structure; 401-First guide rail; 402-First guide seat; 403-Lead screw; 404-Displacement seat; 405-Drive motor; 5-Probe bracket; 6-Probe structure; 601-Mounting port; 602-Wear-resistant slider; 603-Mounting hole; 604-Coil fixing seat; 605-Detection coil; 606-Pressure plate; 607-Spring; 7-Adjusting seat; 8-Drive structure; 801-Connecting seat; 802-Slanted groove; 80 3-Limiting post; 9-Guide structure; 901-Second guide rail; 902-Second guide seat; 10-Push structure; 1001-Third guide rail; 1002-Third guide seat; 1003-Push rod structure; 1101-Fixing frame; 1102-Buffer post; 1103-Buffer spring; 1104-Buffer pad; 12-Limiting frame; 1201-Calibration frame; 1202-Calibration block; 13-Electric push rod; 1301-Limiting frame; 1302-Limiting wheel; 1303-Stop; 14-Radiation resistant camera. Detailed Implementation

[0023] 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, not all, of the embodiments of the present invention. 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.

[0024] 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.

[0025] Example This invention provides a device for detecting oxide film on fuel assembly grids after irradiation, such as... Figures 1 to 6 As shown, it includes a mounting base 1, a guide rail 2 on the side wall of the mounting base 1, a mounting bracket 3 slidably mounted on the guide rail 2, and an adjustment structure 4 on the guide rail 2. The adjustment structure 4 is used to drive the mounting bracket 3 to move back and forth along the extension direction of the guide rail 2. Two probe brackets 5 are provided in pairs on the mounting bracket 3, and probe structures 6 are installed on the opposite side walls of the two probe brackets 5.

[0026] The mounting bracket 3 is equipped with an adjustment seat 7, and both probe holders 5 are slidably connected to the adjustment seat 7. The mounting bracket 3 is provided with a drive structure 8 for driving the adjustment seat 7 to move back and forth along the extension direction of the guide rail 2. When the adjustment seat 7 moves back and forth along the extension direction of the guide rail 2, the probe holders 5 slidably connected to the adjustment seat 7 move closer to or further away from each other.

[0027] Mounting base 1 is used to fix the whole device. Mounting bracket 3 on guide rail frame 2 is driven by adjustment structure 4 to move back and forth along the extension direction of guide rail. When the two probe brackets 5 symmetrically arranged on mounting bracket 3 move along the direction of guide rail under the drive of adjustment seat 7, they move closer or further apart through sliding connection mechanism to achieve adaptive coating detection of fuel rod surface. Adjustment structure 4 controls the axial movement of mounting bracket 3 to cover the entire area to be tested. Drive structure 8 converts the linear movement of adjustment seat 7 into radial movement of probe bracket 5, so that probe structure 6 always keeps in contact with fuel rod surface, thereby realizing contact or detachment scanning detection.

[0028] In some embodiments of the present invention, the positioning structure 4 includes a first guide rail 401 mounted on the guide rail frame 2, a first guide seat 402 slidably connected to the first guide rail 401 mounted on the mounting frame 3, a lead screw 403 rotatably mounted on the mounting base 1, a displacement seat 404 pulsatically connected to the lead screw 403 at the bottom of the mounting frame 3, and a drive motor 405 pulsatically connected to the lead screw 403 mounted on the mounting base 1. The drive motor 405 drives the lead screw 403 to rotate via a belt drive structure, and the lead screw 403 converts the rotational motion of the motor into a reciprocating linear displacement of the mounting frame 3 along the extension direction of the first guide rail 401. The first guide rail 401 and the first guide seat 402 cooperate to ensure that the mounting frame 3 moves smoothly without deflection. The first guide rail 401 and the first guide seat 402 ensure the straightness and repeatability of the movement trajectory of the mounting frame 3, and avoid the increased wear of the structure after long-term reciprocating motion, which would affect the measurement accuracy of the probe structure 6 on the oxide film of the fuel rod.

[0029] In some embodiments of the present invention, the probe structure 6 includes a mounting port 601 opened at the end of the probe holder 5. A wear-resistant slider 602 is slidably disposed in the mounting port 601. A mounting hole 603 is opened on the side wall of the wear-resistant slider 602 facing the bottom of the mounting port 601. A coil fixing seat 604 is disposed in the mounting hole 603. A detection coil 605 is disposed on the outer side wall of the coil fixing seat 604. A pressure plate 606 connected to the probe holder 5 is disposed in the mounting port 601. Two springs 607 are respectively abutting against the wear-resistant slider 602 on the pressure plate 606. The springs 607 are partially embedded in the wear-resistant slider 602. The probe is mounted inside the wear-resistant slider 602 via the coil mounting base 604. During detection, the spring 607 pushes the wear-resistant slider 602 to press firmly against the fuel rod surface. When encountering protrusions or depressions, the wear-resistant slider 602 can slide along the mounting opening 601 to compensate, improving measurement accuracy. The spring 607 provides constant contact pressure, ensuring a constant distance between the detection coil 605 and the fuel rod surface, while also providing cushioning to prevent hard collisions between the probe and the fuel rod, protecting the brittle fuel rod surface. The wear-resistant slider 602 reduces direct wear on the probe, extending its service life, and is replaceable, reducing maintenance costs. The constant pressure ensures the stability of the detection signal, improving the accuracy of oxide film thickness measurement.

[0030] The contact area between the wear-resistant slider 602 and the outer wall of the fuel rod is arc-shaped. During the inspection process, the eddy current probe coil benefits from the adaptive floating mechanism of the probe contact block, which enables it to automatically and flexibly adjust its position to ensure continuous contact with the surface of the inspected part. This achieves high-efficiency and high-repeatability grid oxide film detection, and also reduces the risk of missed detections due to poor contact between the probe and the surface of the inspected part.

[0031] The detection coil 605 is entirely encapsulated within the circular hole of the probe contact block. This integrated design allows for greater flexibility during probe operation while ensuring the coil's safety and stability. The detection coil 605 and the cable utilize a dedicated signal cable with a shielded layer and polyurethane sheath, meeting the requirements for use in radioactive underwater environments. Furthermore, the cable is encased in a stainless steel conduit for protection, further enhancing signal shielding quality.

[0032] Preferably, probe structure 6 employs probe temperature drift resistance technology, addressing temperature drift and calibration issues through a differential eddy current detection probe and a differential method. The detection utilizes a differential connection, eliminating the influence of temperature drift by introducing a compensation current in the measurement circuit that is opposite to the direction of temperature drift, thus minimizing the impact of temperature changes on the output results. After differential processing, the grid oxide film probe exhibits temperature drift resistance, better meeting the requirements of application environments.

[0033] Preferably, the probe coil and probe tooling materials have strong radiation resistance and a stable temperature coefficient, and the cable materials have waterproof, radiation resistance, and good shielding and signal transmission performance, making them suitable for nuclear power plant site environments, ensuring the stability of measurement results, and applicable to the thickness measurement of oxide film on fuel assembly grids in nuclear power plants.

[0034] In some embodiments of the present invention, the drive structure 8 includes two connected seats 801 arranged in pairs. Each connected seat 801 has two inclined grooves 802 on its side wall. The two inclined grooves 802 are in the shape of an "eight" and their reverse extension lines on the side away from the probe structure 6 intersect at an acute angle. The side wall of the adjustment seat 7 is provided with two limiting posts 803. The two limiting posts 803 are slidably arranged in their corresponding inclined grooves 802. The side wall of the mounting frame 3 is provided with a guide structure 9 for guiding the two probe frames 5 to move towards each other. The mounting frame 3 is provided with a pushing structure 10 for pushing the adjustment seat 7 to reciprocate. When the adjusting seat 7 moves, the limiting post 803 on it slides along the inclined groove 802 set in the inclined direction of the connecting seat 801, pushing the two probe frames 5 to move towards or in opposite directions under the guidance of the guide structure 9. The inclined plane mechanism converts the axial movement of the adjusting seat 7 into the radial movement of the probe frame 5, realizing synchronous symmetrical opening and closing, ensuring that the two probes move synchronously, improving the symmetry of the probe structure 6 located on the two probe frames 5 to detect the oxide film of the same grid, improving the accuracy of oxide film thickness measurement, and eliminating the need to repeatedly detect the oxide film of the same grid. This structure is suitable for adaptive clamping detection in narrow spaces.

[0035] In some embodiments of the present invention, the guide structure 9 includes a second guide rail 901 arranged along the width direction of the mounting frame 3, and a second guide seat 902 provided on the probe holder 5, the second guide seat 902 being slidably connected to the second guide rail 901. The probe holder 5 slides along the second guide rail 901 via the second guide seat 902, restricting its movement only along the width direction of the mounting frame 3. The guide rail pair formed by the second guide rail 901 and the second guide seat 902 provides precise guidance for radial movement, preventing the probe holder 5 from swaying or jamming, improving the straightness and stability of the probe's radial movement; reducing frictional losses during operation, extending the life of the mechanism; and ensuring that the probe is perpendicularly aligned with the oxide film surface of the grid.

[0036] In some embodiments of the present invention, a third guide rail 1001 is further provided along the extending direction of the mounting frame 3. The third guide rail 1001 is mounted on the side wall of the mounting frame 3, and a third guide seat 1002 is provided on the side wall of the displacement seat 404. The third guide seat 1002 is slidably connected to the third guide rail 1001. The displacement seat 404 slides along the third guide rail 1001 through the third guide seat 1002, assisting the axial movement of the mounting frame 3. The third guide rail 1001 and the first guide rail 401 form a double guide, enhancing the torsional resistance and load-bearing capacity of the axial movement of the mounting frame 3, further suppressing the vibration of the mounting frame 3, and improving the movement accuracy; it also shares the force of the lead screw 403, improving the structural rigidity.

[0037] In some embodiments of the present invention, the pushing structure 10 includes a push rod structure 1003 mounted on the mounting bracket 3, the telescopic end of which is connected to the side wall of the displacement seat 404. The push rod structure 1003 directly pushes the displacement seat 404 to move axially, thereby driving the mounting bracket 3 and the probe bracket 5 to move. The push rod provides linear power, replacing or assisting the lead screw 403 transmission. The electric push rod 13 has a fast response structure, suitable for rapid positioning.

[0038] In some embodiments of the present invention, a fixing frame 1101 is provided on the side wall of the mounting frame 3, and a buffer post 1102 passes through the side wall of the fixing frame 1101. A buffer spring 1103 connected to the fixing frame 1101 is sleeved on the outer side wall of the buffer post 1102, and a buffer pad 1104 is provided at the end of the buffer post 1102 opposite to the displacement seat 404. When the displacement seat 404 moves to its limit position, the buffer pad 1104 contacts the buffer post 1102, and the buffer spring 1103 absorbs the impact energy. The spring 607 buffer converts the collision kinetic energy into elastic potential energy, achieving soft stopping. This prevents mechanical impact from damaging the probe or fuel rod; reduces motion noise and vibration; and extends the life of the guide rail and transmission components.

[0039] In some embodiments of the present invention, a limiting frame 12 is provided on the side wall of the mounting base 1, and two calibration frames 1201 are provided in pairs on the side wall of the limiting frame 12. A mounting groove is formed on the side wall of the calibration frame 1201 opposite to the probe frame 5, and a plurality of calibration blocks 1202 are equidistantly arranged in the mounting groove along the extending direction of the probe frame 5. Before testing, the probe frame 5 is moved to the position of the calibration frame 1201, so that the probe is aligned with calibration blocks 1202 of different thicknesses for signal calibration. When the testing personnel sample, the correspondence between the eddy current signal and the oxide film thickness is established using calibration blocks 1202 of known thickness, thereby calibrating the testing system, improving testing accuracy, and eliminating probe errors and environmental interference. The calibration process can be automated and integrated, facilitating periodic verification. Multiple thickness calibration blocks 1202 cover a wider measurement range. It also allows the oxide film detection probe to be attached to the grid oxide film sample for underwater online calibration.

[0040] The probe structures on both the left and right sides are calibrated independently, and multiple oxide film standard samples of various specifications are laid flat on the same plane, which can complete the probe calibration at one time, thereby improving the calibration efficiency.

[0041] In some embodiments of the present invention, an electric push rod 13 is installed inside the mounting base 1. A limiting frame 12 is provided on the telescopic end of the electric push rod 13, and a limiting wheel 1302 is rotatably provided at the end of the limiting frame 12. A stop block 1303 is provided on the side wall of the mounting frame 3 to abut against the limiting frame 12. The electric push rod 13 pushes the limiting frame 12 upward, and the limiting wheel 1302 contacts the stop block 1303 on the side wall of the mounting frame 3, limiting the positional movement of the mounting frame 3 during the detection process. The telescopic limiting mechanism locks the position of the mounting frame 3 during detection and retracts after detection to allow the mounting frame 3 to move. This enhances the stability of the mounting frame 3 during detection and avoids signal fluctuations caused by probe micro-movements; the rolling contact of the limiting wheel 1302 reduces wear; and the electric control facilitates integration into the automatic detection process.

[0042] This structure is also equipped with two sets of radiation-resistant cameras 14 to observe the position of the grid frame on both sides and the probe feeding. The radiation-resistant cameras 14 are mounted on both sides of the mounting base 1 via a frame to ensure that the probe fits well with both sides of the grid frame, effectively ensuring stable and reliable data acquisition of oxide film thickness.

[0043] This structure has been applied to the thickness measurement of the oxide film on the surface of the fuel assembly grid of Qinshan Nuclear Power Plant N36-CF3, and can be directly extended to the measurement of oxide film on the grid of other pressurized water reactor nuclear power units in China.

[0044] The detection process for the core lattice oxide film using this structure is as follows: When inspecting the oxide film on the fuel assembly grid after it leaves the reactor, the grid oxide film inspection mechanism is installed on an underwater inspection platform. The probe measuring fixture is adjusted according to the width and length of the grid so that the probe structure 6 flexibly fits the grid surface, ensuring stable grid contact and that the contact force between the probe and the grid does not exceed the limit.

[0045] First, connect the eddy current meter and the test probe structure 6, and open the measurement software; Then, by controlling the movement of the probe structure 6 through the grid oxide film detection mechanism, the detection sensitivity of the special grid oxide film standard sample is calibrated. After completing the detection sensitivity calibration, the component to be tested is hoisted to the testing station; Under the monitoring of the radiation-resistant camera 14, the height of the components is adjusted so that the grid oxide film probe structure 6 is at the same level as the grid being inspected; By using the drive structure 8, the two probe frames 5 are opened, and the underwater inspection platform is controlled to move the probe structure 6 located on the probe frame 5 forward to the fuel assembly grid area. The drive structure 8 is controlled to adjust the width of the two probe frames 5 to contact the left and right outer grids of the fuel assembly. During the process of the grids driving the two probe structures 6 to retreat, the eddy current detection signals of the oxide film thickness of the grids on both sides are collected sequentially. The collected eddy current detection signals are remotely transmitted to the shore-based eddy current acquisition software via an underwater communication cable for the acquisition and analysis of the oxide film signal at that location. After completing this step, proceed to the next grid oxide film thickness test, until all grid oxide film tests for this component are completed.

[0046] 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 device for detecting oxide film on a fuel assembly grid after irradiation, characterized in that, The device includes a mounting base, a guide rail frame on the side wall of the mounting base, a mounting bracket slidably mounted on the guide rail frame, and an adjustment structure on the guide rail frame for driving the mounting bracket to reciprocate along the extension direction of the guide rail frame. The mounting bracket is provided with two probe brackets in pairs, and probe structures are installed on the opposite side walls of the two probe brackets. The mounting bracket is equipped with an adjustment seat, and both probe holders are slidably connected to the adjustment seat. The mounting bracket is provided with a drive structure, which is used to drive the adjustment seat to move back and forth along the extension direction of the guide rail. When the adjustment seat moves back and forth along the extension direction of the guide rail, the probe holders slidably connected to the adjustment seat move closer to each other.

2. The device for detecting oxide film on a fuel assembly grid after irradiation according to claim 1, characterized in that, The adjustment structure includes a first guide rail mounted on the guide rail frame, a first guide seat slidably connected to the first guide rail mounted on the mounting frame, a lead screw rotatably mounted on the mounting base, a displacement seat driven by the lead screw at the bottom of the mounting frame, and a drive motor driven by the lead screw on the mounting base.

3. The device for detecting oxide film on a fuel assembly grid after irradiation according to claim 1, characterized in that, The probe structure includes a mounting port at the end of the probe holder, a wear-resistant slider that slides within the mounting port, and a mounting hole on the side wall of the wear-resistant slider facing the bottom of the mounting port. A coil fixing seat is provided within the mounting hole, and a detection coil is provided on the outer side wall of the coil fixing seat. A pressure plate connected to the probe holder is provided within the mounting port, and two springs that abut against the wear-resistant slider are provided on the pressure plate. Part of the springs are embedded within the wear-resistant slider.

4. The device for detecting oxide film on a fuel assembly grid after irradiation according to claim 2, characterized in that, The driving structure includes two connected seats arranged in pairs. Each connected seat has two inclined slots on its side wall. The two inclined slots are in the shape of an "8". The reverse extension lines of the two inclined slots on the side away from the probe structure intersect at an acute angle. The side wall of the adjusting seat is provided with two limiting posts. The two limiting posts are slidably arranged in their corresponding inclined slots. The side wall of the mounting frame is provided with a guide structure for guiding the two probe frames to move towards each other. The mounting frame is provided with a pushing structure for pushing the adjusting seat to reciprocate.

5. The device for detecting oxide film on a fuel assembly grid after irradiation according to claim 4, characterized in that, The guide structure includes a second guide rail arranged along the width direction of the mounting bracket, and a second guide seat is provided on the probe bracket, the second guide seat being slidably connected to the second guide rail.

6. The device for detecting oxide film on a fuel assembly grid after irradiation according to claim 4, characterized in that, It also includes a third guide rail that is provided along the extension direction of the mounting frame. The third guide rail is mounted on the side wall of the mounting frame. The side wall of the displacement seat is provided with a third guide seat, and the third guide seat is slidably connected to the third guide rail.

7. The device for detecting oxide film on a fuel assembly grid after irradiation according to claim 6, characterized in that, The pushing structure includes a push rod structure mounted on the mounting bracket, and the telescopic end of the push rod structure is connected to the side wall of the displacement seat.

8. The device for detecting oxide film on a fuel assembly grid after irradiation according to claim 7, characterized in that, The mounting bracket has a fixing frame on its side wall, and a buffer column passes through the side wall of the fixing frame. A buffer spring connected to the fixing frame is sleeved on the outer side wall of the buffer column, and a buffer pad is provided at the end of the buffer column opposite to the displacement seat.

9. The device for detecting oxide film on a fuel assembly grid after irradiation according to claim 1, characterized in that, The mounting base has an upper limit frame on its side wall. Two calibration frames are provided in pairs on the side wall of the limit frame. The calibration frames have mounting grooves on their side walls opposite to the probe frame. Several calibration blocks are provided at equal intervals in the mounting grooves along the extension direction of the probe frame.

10. The device for detecting oxide film on a fuel assembly grid after irradiation according to claim 1, characterized in that, An electric push rod is installed inside the mounting base. A limit frame is provided on the telescopic end of the electric push rod. A limit wheel is rotatably provided at the end of the limit frame. A stop block that abuts against the limit frame is provided on the side wall of the mounting frame.

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