Nuclear fuel assembly deformation underwater measuring device and underwater measuring mechanism thereof

Abstract

A nuclear fuel assembly deformation underwater measurement device and an underwater measurement mechanism thereof, the device comprising an underwater measurement mechanism, the underwater measurement mechanism comprising: a frame comprising a multi-layer support provided with a through hole or a through groove for accommodating a nuclear fuel assembly to be measured; the clamping part is arranged at the upper part of the rack and is provided with a clamping position and a releasing position relative to the rack, and the clamping part is used for radially positioning and clamping the nuclear fuel assembly to be tested; the supporting component is arranged at the bottom of the rack and is provided with a supporting position and a retracting position relative to the rack, and the supporting component axially positions the nuclear fuel assembly to be tested and converts the stress state of the nuclear fuel assembly to be tested; and the plurality of measuring parts are respectively arranged on the corresponding brackets along the height direction of the to-be-measured nuclear fuel assembly, and the plurality of measuring parts synchronously measure the deformation data of the to-be-measured nuclear fuel assembly in multiple sections and multiple directions.

Description

Technical Field

[0001] This utility model relates to nuclear fuel assembly measurement technology, and in particular to an underwater measuring device and its underwater measuring mechanism for nuclear fuel assembly deformation in a high-level radioactive environment. Background Technology

[0002] Nuclear fuel assemblies are crucial components of nuclear power systems, consisting of fuel rods, fuel cladding, and upper and lower mounting bases. The fuel cladding encloses the fuel rods, acting as a barrier to prevent the escape of radioactive particles. Factors such as assembly stress, thermal expansion, and fuel pellet swelling can cause combined deformations in nuclear fuel assemblies, including bending, twisting, and tilting. This results in prolonged refueling windows, impacting the economic efficiency of the nuclear power plant. Severely deformed fuel assemblies are prone to scraping and breaking from other fuel assemblies during the refueling process, causing production accidents and severely affecting the refueling and unloading process, significantly extending the main overhaul timeline of the nuclear power plant.

[0003] For deformed nuclear fuel assemblies, measuring the deformation before loading allows for the acquisition of deformation data. By optimizing the loading process and the placement orientation of the fuel assemblies, loading efficiency can be improved, the main overhaul time of the nuclear power plant can be shortened, and the risk of scratch damage to the fuel assemblies can be significantly reduced. Nuclear fuel assemblies are characterized by radioactivity, large size, and high temperature; therefore, remote automatic measurement is required in boric acid water. The standard "Post-Irradiation Inspection of Pressurized Water Reactor Rod Bundle-Type Nuclear Fuel Assemblies Part 3: Underwater Dimensional Measurement of Nuclear Fuel Assemblies" (EJ / T 20150.3-2021), Section 4, mentions two measurement methods: the video image comparison method and the LVDT (Linear Variable Differential Transformer) method for underwater measurement of the external dimensions of irradiated nuclear fuel assemblies.

[0004] Existing technologies employ machine vision to measure the suspension attitude and deformation of nuclear fuel assemblies. However, these technologies cannot avoid the impact of insufficient underwater light, temperature fields, and turbulence on measurement accuracy, resulting in low reliability. To overcome the influence of environmental factors such as ambient light and thermal turbulence, multiple laser generators project lasers onto the surface of the fuel assembly under test. An image capture device then captures images of the laser-affected surface, thus detecting the suspension attitude of the fuel assembly. However, this requires multiple radiation-resistant laser generators and image capture devices, which are expensive and cannot avoid the impact of irregular light refraction caused by turbulence on measurement accuracy. Another approach involves using a single-point contact measurement method to measure nuclear fuel assemblies. A further improvement involves placing a lifting platform around the perimeter of the spent fuel assembly, equipped with multiple linear displacement sensors to collect deformation data from the same cross-section of the assembly. However, in underwater environments with nuclear radiation, the use of numerous moving parts and pneumatic components necessitates a complex mechanism, requiring the lifting platform to ascend and descend a full stroke for each measurement. This places high demands on the rigidity and installation accuracy of the frame, making maintenance difficult and resulting in low reliability of the measurement function. Alternatively, the platform can be moved up and down multiple times to measure gauge blocks in layers before measurement to reduce measurement errors, replacing standard nuclear fuel assemblies. However, this method is time-consuming and not suitable for rapid measurement of nuclear fuel assemblies. Furthermore, the linear displacement sensor makes point contact with the nuclear fuel assembly, making it impossible to avoid the influence of the concave shape of the assembly on the measured dimensions. Existing devices do not employ a modular design to enable rapid assembly and disassembly of modules, leading to inconvenient maintenance and long repair times.

[0005] In addition, the top of the nuclear fuel assembly is subjected to stress during the loading process, and the bottom support is subjected to stress after loading is completed. The deformation of the nuclear fuel assembly varies under different stress conditions, which affects the control of the loading and unloading process. Existing nuclear fuel assembly measuring devices cannot measure nuclear fuel assemblies under different stress conditions.

[0006] In summary, existing technologies for underwater measurement of nuclear fuel assembly deformation in high-level radioactive environments have the following problems:

[0007] Insufficient underwater light, temperature field, and turbulence affect measurement accuracy; it is difficult to measure different stress postures of nuclear fuel assemblies; maintenance of measurement devices is difficult in underwater, irradiated, and high-temperature environments; the concave shape of nuclear fuel assemblies affects measurement accuracy; measurement efficiency is low; the measurement mechanism has a complex structure and is inconvenient to maintain; and the measurement equipment is costly. Utility Model Content

[0008] The technical problem to be solved by this utility model is to provide an underwater measuring device for nuclear fuel assembly deformation and its underwater measuring mechanism, which addresses the above-mentioned deficiencies of the prior art.

[0009] To achieve the above objectives, this utility model provides an underwater measurement mechanism for the deformation of nuclear fuel assemblies, comprising:

[0010] frame;

[0011] A clamping component is disposed on the upper part of the frame and has a clamping position and a releasing position relative to the frame. The clamping component is radially positioned and clamps the nuclear fuel assembly to be tested.

[0012] A support component, disposed at the bottom of the frame, has a supporting position and a retracted position relative to the frame. The support component axially positions the nuclear fuel assembly under test and converts the stress state of the nuclear fuel assembly under test.

[0013] Multiple measuring components are respectively installed on corresponding rack interfaces along the height direction of the nuclear fuel assembly under test. The multiple measuring components simultaneously measure the deformation data of the nuclear fuel assembly under test in multiple sections and directions.

[0014] The aforementioned underwater measuring device for nuclear fuel assembly deformation includes a frame with multiple layers of locating pin holes and threaded holes for quick assembly and disassembly of the measuring components.

[0015] The underwater measurement mechanism for the deformation of the nuclear fuel assembly described above includes a measuring plate, a connector, and a displacement sensor. The displacement sensor is connected to the measuring plate via the connector. The measuring rod of the displacement sensor extends adaptively via an elastic element. The measuring plate achieves contact measurement by adaptively fitting the nuclear fuel assembly under test through a slight angular deformation along the horizontal direction.

[0016] The underwater measurement mechanism for nuclear fuel assembly deformation described above includes a measurement component that further comprises a retraction drive and a retraction link. The retraction link is connected to the retraction drive and the connecting component, respectively. The retraction drive drives the retraction link to extend or retract to control the contact or separation of the measurement plate from the nuclear fuel assembly under test.

[0017] In the aforementioned underwater measurement mechanism for nuclear fuel assembly deformation, the measuring component is configured to correspond to the grid and lower tube seat of the nuclear fuel assembly under test, and the measuring plate is in surface contact with the grid and lower tube seat of the nuclear fuel assembly under test for measurement.

[0018] The aforementioned underwater measurement mechanism for nuclear fuel assembly deformation includes a support component comprising a support plate, a support spring, a lever, a limit switch, and a fixed plate. The support plate is mounted on the support spring and its upper limit position is limited by a spring limiter. When the support plate is at its upper limit position, the preload of the support spring is less than the weight of the nuclear fuel assembly under test. The limit switch is mounted on the fixed plate. One end of the lever is connected to a power mechanism, and the other end of the lever is connected to the support plate. The power mechanism controls the support plate to switch between the supported position and the retracted position via the lever.

[0019] The underwater measurement mechanism for nuclear fuel assembly deformation described above includes a support component that further comprises a support guide plate and a positioning pin for guiding and radially positioning the nuclear fuel assembly under test, respectively disposed on the support plate; the spring limiting member is located on the fixed plate and connected to the support spring.

[0020] The underwater measurement mechanism for the deformation of the nuclear fuel assembly described above includes a clamping component comprising a positioning component and a swinging component. The swinging component is located on one side of the nuclear fuel assembly to be tested and is connected to a power mechanism; the positioning component is located on the other side of the nuclear fuel assembly to be tested and is connected to the power mechanism.

[0021] The underwater measurement mechanism for nuclear fuel assembly deformation described above, wherein the positioning component includes a positioning flap and a flipping drive, one end of the flipping drive is connected to the positioning flap, and the flipping drive controls the positioning flap to contact or separate from the nuclear fuel assembly to be tested.

[0022] The underwater measurement mechanism for nuclear fuel assembly deformation described above, wherein the swinging component includes a swing arm, a connecting rod, and a torsion spring, one end of the swing arm is connected to the torsion spring, and the other end of the swing arm is connected to the power mechanism through the connecting rod, and the power mechanism controls the swing arm to be in the clamping position or the release position through the connecting rod.

[0023] To better achieve the above objectives, this utility model also provides an underwater measuring device for nuclear fuel assembly deformation, which includes the aforementioned underwater measuring mechanism.

[0024] The beneficial effects of this utility model are as follows:

[0025] This utility model's underwater measurement mechanism employs contact measurement, effectively avoiding interference from environmental factors such as insufficient underwater lighting, temperature field changes, and turbulence, ensuring measurement accuracy. Through the lifting and adjusting of the support components, deformation measurement of the nuclear fuel assembly is achieved between its top-suspended and bottom-supported states. By placing the above-water drive mechanism, control box, and host computer above the water surface, radiation protection requirements are reduced, as are manufacturing, sealing, and maintenance costs. Simultaneously, above-water personnel can operate and maintain the device closely, effectively reducing operational difficulty. The frame can adopt an integrated structure with lifting points and side wall mounting points, allowing the underwater device to be directly hoisted above the water for maintenance and debugging in the above-water environment, effectively reducing the difficulty of equipment manufacturing, installation, debugging, and maintenance. The measurement components adopt a modular design, with each layer of measurement components allowing for quick assembly and disassembly from the frame. Measurement components of the same model are interchangeable, and different models can be replaced to adapt to different types of nuclear fuel assemblies or to different heights of the same fuel assembly. The modular design of the grid reduces installation and maintenance requirements and improves the expandability of the device. Multiple measuring components are arranged longitudinally along the height of the nuclear fuel assembly grid on the frame, avoiding frequent lifting and lowering of the measuring sensors during measurement. This simplifies the structure of the measuring device, reduces degrees of freedom, and facilitates inspection and maintenance. The measuring plate contacts the surface of the nuclear fuel assembly, overcoming the influence of single-point indentations on measurement accuracy. The use of displacement sensors is more cost-effective than radiation-resistant lasers and video sensors, giving it better market competitiveness. All measuring components of the underwater measuring device can simultaneously perform a one-time, integrated measurement of a standard nuclear fuel assembly to obtain calibration data. The measurement data is compared with the calibration data to generate deformation data. The measurement benchmark can be updated simply by re-measuring the standard nuclear fuel assembly to obtain calibration data, transferring the measurement benchmark from the equipment to the standard nuclear fuel assembly. This effectively eliminates the impact of disassembly and maintenance of measuring components on measurement accuracy, reduces manufacturing and installation difficulty, and offers high reliability and good cost advantages.

[0026] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments, but this is not intended to limit the present invention. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the device structure according to an embodiment of the present invention;

[0028] Figure 2 This is a schematic diagram of the working state of the device according to an embodiment of the present invention;

[0029] Figure 3 This is a schematic diagram of the device installation and fixing according to an embodiment of the present invention;

[0030] Figure 4AThis is a schematic diagram of the device hanging point fixing according to an embodiment of the present invention;

[0031] Figure 4B This is a schematic diagram of the installation of the measuring component according to an embodiment of the present invention;

[0032] Figure 5 This is a schematic diagram of an underwater measuring mechanism according to an embodiment of the present invention;

[0033] Figure 6 This is a schematic diagram of the power mechanism according to an embodiment of the present invention;

[0034] Figure 7 This is a schematic diagram of a clamping component according to an embodiment of the present invention;

[0035] Figure 8 This is a side view of a clamping component according to an embodiment of the present invention;

[0036] Figure 9 This is a bottom view of a clamping component according to an embodiment of the present invention;

[0037] Figure 10 This is a schematic diagram of a support component according to an embodiment of the present invention;

[0038] Figure 11A This is a schematic diagram of the top suspension posture of a nuclear fuel assembly according to an embodiment of the present invention;

[0039] Figure 11B for Figure 11A A magnified view of a portion of the clamping component;

[0040] Figure 11C for Figure 11A Enlarged view of a portion of the supporting components;

[0041] Figure 12A This is a schematic diagram of the bottom support posture of a nuclear fuel assembly according to an embodiment of the present invention;

[0042] Figure 12B for Figure 12A A magnified view of a portion of the clamping component;

[0043] Figure 12C for Figure 12A Enlarged view of a portion of the supporting components;

[0044] Figure 13 This is a schematic diagram of the measuring component structure according to an embodiment of the present invention;

[0045] Figure 14 This is a schematic diagram of the vertical arrangement of two sets of measuring components for measuring the same cross-section in Embodiment 1 of this utility model;

[0046] Figure 15This is a schematic diagram of the three sets of measuring components arranged in a T-shape for measuring the same cross-section in Embodiment 2 of this utility model;

[0047] Figure 16 This is a schematic diagram of two sets of measuring components arranged at 60° to measure the same cross-section in Embodiment 3 of this utility model;

[0048] Figure 17 This is a schematic diagram of three sets of measuring components arranged in pairs at 60° to measure the same cross-section in Embodiment 4 of this utility model.

[0049] Among them, the attached reference numerals

[0050] 1. Underwater Measurement Mechanism

[0051] 11 racks

[0052] 111 hook

[0053] 112 hanging point

[0054] 12 clamping components

[0055] 121 positioning component

[0056] 1211 Positioning Flip Board

[0057] 1212 Tilting drive component 122 Clamping component

[0058] 1221 balance bar

[0059] 1222 Link

[0060] 1223 Torsion Spring

[0061] 13 Measuring Components

[0062] 131 measuring plate

[0063] 132 connector

[0064] 133 displacement sensor

[0065] 134 retraction drive

[0066] 135 retraction linkage

[0067] 14 Supporting Components

[0068] 141 support plate

[0069] 142 support spring

[0070] 143 Spring Limiting Component

[0071] 144 levers

[0072] 145 support guide plate

[0073] 146 positioning pin

[0074] 147 Limit Switch

[0075] 148 Fixing Plate

[0076] 2 pipelines

[0077] 3. Host computer

[0078] 4. Control box 5. Power mechanism

[0079] 51 linear drive unit

[0080] 52 steel cable

[0081] 53 guide wheels

[0082] 6 nuclear fuel assemblies to be tested

[0083] 61 Upper tube seat

[0084] 62 shelves

[0085] 63 lower tube seat

[0086] 7 hooks

[0087] 8 water surface Detailed Implementation

[0088] The structural and working principles of this utility model will be described in detail below with reference to the accompanying drawings:

[0089] See Figures 1-5 , Figure 1 This is a schematic diagram of the device structure according to an embodiment of the present invention. Figure 2 This is a schematic diagram of the working state of the device according to an embodiment of the present invention. Figure 3 This is a schematic diagram of the device installation and fixing according to an embodiment of the present invention. Figure 4A This is a schematic diagram of the device hanging point fixing according to an embodiment of the present invention. Figure 4B This is a schematic diagram of the installation of the measuring component according to an embodiment of the present invention. Figure 5This is a schematic diagram of the underwater measuring mechanism 1 according to an embodiment of the present invention. The underwater measuring device for nuclear fuel assembly deformation of the present invention is suitable for underwater measurement of nuclear fuel assembly deformation in a high-level radioactive environment. It includes: an underwater measuring mechanism 1 for contact measurement of the cross-sectional deformation dimensions of a nuclear fuel assembly 6 to be tested, comprising a frame 11, a clamping component 12, multiple measuring components 13, and a supporting component 14. The nuclear fuel assembly 6 to be tested includes an upper tube seat 61, a grid frame 62, and a lower tube seat 63. The frame 11 can be a universal connecting column, connecting the clamping component 12, the supporting component 14, and the multiple measuring components 13 via a quick-connect interface. The frame 11 includes a multi-layer support, which has through holes or slots for accommodating the nuclear fuel assembly 6 to be tested. The supporting component 14 is located at the bottom of the frame 11 and has a supporting position and a retracted position relative to the frame 11, used for axial positioning and force state conversion of the nuclear fuel assembly 6 to be tested. The clamping component 12 is located on the upper part of the frame 11. The underwater measuring mechanism 1 has a clamping position and a release position relative to the frame 11, which are used for radial positioning and clamping of the nuclear fuel assembly 6 to be tested; multiple measuring components 13 are respectively set on corresponding supports along the height direction of the nuclear fuel assembly 6 to be tested, which are used to simultaneously measure the deformation data of the nuclear fuel assembly 6 to be tested in multiple sections and multiple directions. The measuring components 13 are installed and positioned by hooks and pins, and fastened to the frame 11 by bolts. The measuring components can be quickly installed and removed by removing and installing bolts; at least one set of power mechanism 5 is connected to the underwater measuring mechanism 1; the control box 4 is used to control the movement of each driving component, and is connected to the above-water driving mechanism 5 and the underwater measuring mechanism 1 respectively; the host computer 3 is used to obtain and intuitively display the deformation data of the nuclear fuel assembly 6 to be tested obtained by the measuring components 13 through data fitting and three-dimensional deformation model reconstruction, and can be connected to the control box 4 through pipeline 2.

[0090] The underwater measuring mechanism 1 and the host computer 3 are controlled and communicated via pipeline 2, enabling long-distance measurement. The host computer 3 can process deformation data, and through data fitting and three-dimensional deformation model reconstruction, it can intuitively display the deformation of the nuclear fuel assembly. The host computer 3 has external communication capabilities and can output the deformation data of the nuclear fuel assembly. The nuclear fuel assembly cross-section measured by the measuring component 13 is located at the nuclear fuel assembly grid 62 and the lower tube seat 63. The nuclear fuel assembly grid 62 and the lower tube seat 63 are rigid, and contact measurement on them will not cause secondary deformation of the nuclear fuel assembly.

[0091] See Figure 6 , Figure 6This is a schematic diagram of a water-based drive mechanism 5 according to an embodiment of the present invention. In this embodiment, the power mechanism 5 is installed and fixed on the ground of a nuclear power plant fuel building, providing power to the underwater measurement mechanism 1. The power mechanism 5 includes a linear drive component 51, a steel cable 52, and multiple sets of guide wheels 53. The linear drive component 51 is connected to the steel cable 52 via a quick-release connector, and the linear drive component 51 is connected to the underwater measurement mechanism 1 via the steel cable 52. The guide wheels 53 are used for long-distance guidance and / or direction change of the steel cable 52.

[0092] In this embodiment, the linear drive component 51 can be a cylinder, hydraulic cylinder, or electric motor, and the steel cable 52 can be a steel wire rope or chain. The guide wheel 53 has a long-distance guiding function for the steel cable 52, preventing mutual friction between multiple steel cables 52; the guide wheel 53 can also realize the direction change of the steel cable 52, so that the measuring component 13 can move in any direction.

[0093] See Figures 7-9 , Figure 7 This is a schematic diagram of the clamping component 12 according to an embodiment of the present invention. Figure 8 This is a side view of the clamping component 12 according to an embodiment of the present invention. Figure 9 This is a bottom view of a clamping component 12 according to an embodiment of the present invention. The clamping component 12 in this embodiment includes a clamping member 122 and a positioning member 121. The positioning member 121 is located on one side of the nuclear fuel assembly 6 to be tested, and is used to provide X-axis and Y-axis positioning references for the nuclear fuel assembly 6 to be tested. The clamping member 122 is located on the other side of the nuclear fuel assembly 6 to be tested, and is used to clamp the upper tube seat 61 to achieve X-axis and Y-axis positioning of the nuclear fuel assembly 6 to be tested. Preferably, the mounting plane of the positioning member 121 is coplanar with the mounting plane of the clamping member 122 and is perpendicular to the vertical direction of the nuclear fuel assembly. The positioning component 121 includes a positioning flap 1211 and a flipping drive component 1212. One end of the flipping drive component 1212 is connected to the positioning flap 1211, and the flipping drive component 1212 is connected to the power mechanism 5 through a pipeline 2. The power mechanism 5 controls the positioning flap 1211 to contact or separate from the nuclear fuel assembly 6 under test through the flipping drive component 1212. The clamping component 122 includes a swing rod 1221, a connecting rod 1222, and a torsion spring 1223. One end of the swing rod 1221 is connected to the torsion spring 1223, and the other end of the swing rod 1221 is connected to the power mechanism 5 through the connecting rod 1222 and a steel cable 52. The power mechanism 5 controls the swing rod 1221 to be in the clamping position and the release position through the connecting rod 1222. In this process, the swing arm 1221 releases the upper tube seat 61 under the action of the torsion spring 1223; the steel cable 52 passes through the guide wheel 53 and connects to the connecting rod 1222; the power mechanism 5 pulls the swing arm 1221 back through the steel cable 52 and clamps the upper tube seat 61.

[0094] See Figures 10-12C , Figure 10 This is a schematic diagram of the support component 14 according to an embodiment of the present invention. Figure 11A This is a schematic diagram of the upper hoisting posture of a nuclear fuel assembly according to an embodiment of the present invention. Figure 11B for Figure 11A A magnified view of a portion of the image. Figure 11C for Figure 11A Enlarged view of a portion of the supporting components. Figure 12A This is a schematic diagram of the bottom support posture of a nuclear fuel assembly according to an embodiment of the present invention. Figure 12B for Figure 12A Enlarged view of a portion of the clamping component. Figure 12C for Figure 12A A partial enlarged view of the support component. In this embodiment, the support component 14 is located at the bottom of the frame 11 and is used to achieve axial positioning and force attitude conversion of the nuclear fuel assembly 6 under test. It includes a support plate 141, a support spring 142, a spring limiting member 143, a lever 144, a support guide plate 145, a positioning pin 146, a limit switch 147, and a fixing plate 148. The support plate 141 is mounted and supported on the support spring 142, that is, the support plate 141 is fixed around its perimeter by the support spring 142, providing vertical support and positioning for the nuclear fuel assembly 6 under test. The spring limiting member 143 is located on the fixing plate 148 and connected to the support spring 142 to limit the upper limit position of the support plate 141. When the support plate 141 is at its upper limit position, the preload of the support spring 142 is slightly less than the weight of the nuclear fuel assembly 6 under test. During the hoisting and positioning of the nuclear fuel assembly 6, the support plate 141 moves slightly downwards. The limit switch 147 is fixed to the fixed plate 148 and is used to detect whether the nuclear fuel assembly under test is in position. One end of the lever 144 is connected to the steel cable 52 of the power mechanism 5, and the other end of the lever 144 is connected to the support plate 141. The power mechanism 5 uses the steel cable 52 to extend and retract the lever 144, controlling the support plate 141 to switch between the supported position and the retracted position, thus achieving the lifting and lowering control of the support plate 141. When the support plate 141 descends, it disengages from the nuclear fuel assembly 6 under test, and the force on the nuclear fuel assembly 6 changes from being at the bottom to being at the top, completing the force posture conversion.

[0095] See Figure 13 , Figure 13This is a schematic diagram of the measuring component 13 according to an embodiment of the present invention. The measuring component 13 of this embodiment enables contact measurement of the cross-sectional deformation dimensions of nuclear fuel assemblies. It is preferably an integrated structure, facilitating overall hoisting and installation. A hanging point 112 can be provided at the rear of the frame 11 of the underwater measuring mechanism 1. It can be installed on hooks 7 on the wall below the water level 8 of the spent fuel storage pool, fuel transfer bin, or container loading well in a nuclear power plant's nuclear fuel building, or placed on the pool bottom using anchor bolts. The underwater measuring mechanism 1 can be hoisted to its working position using the hooks 111 mounted on the frame 11. After installation, the underwater measuring mechanism 1 can be calibrated using standard nuclear fuel assemblies to reduce processing and installation errors and ensure measurement accuracy. The measuring component 13 includes a measuring plate 131, a connector 132, and a displacement sensor 133. The displacement sensor 133 is connected to the measuring plate 131 via the connector 132. The measuring rod of the displacement sensor 133 extends adaptively via a built-in elastic element. The measuring plate 131 adaptively conforms to the nuclear fuel assembly 6 under test by undergoing a slight angular deformation along the horizontal direction to achieve contact measurement. Preferably, the measuring component 13 is positioned corresponding to the grid 62 and lower tube seat 63 of the nuclear fuel assembly 6 under test. The measuring plate 131 and the grid 62 and lower tube seat 63 of the nuclear fuel assembly 6 under test are in surface contact to avoid secondary deformation and to prevent the concave shape of the outer wall of the nuclear fuel assembly 6 under test from affecting the measurement of its external dimensions. The measuring plate 131 adopts a hinged or thin plate structure, which can undergo slight angular deformation in the horizontal direction under stress. This allows the measuring plate 131 to adaptively fit with the nuclear fuel assembly 6 under test, enabling contact measurement of the nuclear fuel assembly 6 under test. The deformation data is not affected by environmental factors such as insufficient underwater light, temperature field and turbulence, ensuring measurement accuracy.

[0096] In another embodiment of this utility model, the measuring component 13 may further include a retraction drive 134 and a retraction connecting rod 135. The retraction drive 134 is connected to the power mechanism 5 via a pipeline 53, and the retraction drive 134 is connected to the connecting member 132 via the retraction connecting rod 135. The retraction drive 134 controls the contact or separation between the measuring plate 131 and the nuclear fuel assembly 6 under test by driving the extension or retraction of the retraction connecting rod 135. In this embodiment, the built-in elastic element of the displacement sensor 133 is preferably a spring, which can realize the adaptive extension of the measuring rod. The displacement data of the displacement sensor 133 can be output remotely via the pipeline 2 to realize remote measurement of the deformation size of the nuclear fuel assembly. There can be k displacement sensors 133 in a measuring component 13, where k≥2. The displacement sensor 133 adopts a waterproof, radiation-resistant, and high-temperature-resistant structure, which can be used in underwater, irradiated, and temperature field changing environments. It is preferably an LVDT (linear variable differential transformer), which realizes accurate measurement of displacement by converting the displacement of the measuring rod into an electrical signal. The measuring components 13 can be arranged in 3-16 layers on the frame 11, along the vertical direction, and can simultaneously measure multiple cross-sections of the nuclear fuel assembly 6 to be tested. The underwater measuring mechanism 1 can have n sets of measuring components 13 on the same measuring cross-section of the frame 11, where n≥2.

[0097] Example 1

[0098] like Figure 14 As shown, when the cross-section of the nuclear fuel assembly 6 to be tested is quadrilateral, and the underwater measuring mechanism 1 includes two sets of measuring components 13 in the same measuring cross-section, the two sets of measuring components 13 are arranged in the vertical direction, and the positioning surfaces of the measuring components 13 and the clamping components 12 are in the same direction. The two sets of measuring components 13 are used to measure the deformation dimensions of two adjacent surfaces in the same cross-section of the quadrilateral nuclear fuel assembly. Based on the known side length of the cross-section of the nuclear fuel assembly 6 to be tested, the positions of the other two surfaces can be determined. Combined with the digital fitting method, the overall deformation data of the measuring cross-section can be obtained.

[0099] The specific measurements are as follows: The underwater measuring mechanism 1 is hoisted to a position below the water surface 8 of the spent fuel storage pool in the fuel plant, and the frame 11 is fixedly installed against the pool's sidewall. A standard nuclear fuel assembly is hoisted into the underwater measuring mechanism 1 and placed on the support component 14 for axial positioning. The measuring plates 131 of the two sets of measuring components 13 extend and fit against the sidewall of the standard nuclear fuel assembly. Measurement data from the bottom support posture of the standard nuclear fuel assembly is read as a calibration reference to calibrate the measurement origin of the measuring component 13. The nuclear fuel assembly 6 to be measured is hoisted into the underwater measuring mechanism 1 and placed on the support component 14 for axial positioning. The measuring plates 131 of the two sets of measuring components 13 extend and fit against the sidewall of the standard nuclear fuel assembly. The deformation data of the bottom support posture of the fuel assembly 6 under test is read from the side wall of the fuel assembly 6. The host computer 3 performs data fitting and three-dimensional deformation model reconstruction on the deformation data to intuitively display the deformation of the fuel assembly 6 under test when the bottom support posture is displayed. The support plate 141 of the support component 14 descends, the top of the fuel assembly 6 under test is subjected to force, and the clamping component 12 clamps the fuel assembly 6 under test to achieve radial positioning and clamping. The deformation data of the top suspension posture of the fuel assembly 6 under test is read. The host computer 3 performs data fitting and three-dimensional deformation model reconstruction on the deformation data to intuitively display the deformation of the fuel assembly 6 under test when the top suspension posture is displayed. The measuring component 13 and the clamping component 12 are reset, the fuel assembly 6 under test is lifted away, and the measurement ends.

[0100] Example 2

[0101] like Figure 15 As shown, when the cross-section of the nuclear fuel assembly 6 under test is quadrilateral, and the underwater measuring mechanism 1 includes three sets of measuring components 13 on the same measuring cross-section, the three sets of measuring components 13 are arranged in a T-shape. The three sets of measuring components 13 are used to measure the deformation dimensions of three surfaces on the same cross-section of the quadrilateral nuclear fuel assembly 6 under test. Based on the known side length of the cross-section of the nuclear fuel assembly 6 under test, the position of the remaining surface can be determined. Combined with the digital fitting method, the overall deformation data of the cross-section can be obtained.

[0102] The specific measurement process is as follows: The underwater measuring mechanism 1 is hoisted to a position below the water surface 8 of the spent fuel storage pool in the fuel plant, and the frame 11 is fixedly installed against the side wall of the pool; a standard nuclear fuel assembly is hoisted into the underwater measuring mechanism 1, and the standard nuclear fuel assembly is placed on the support component 14 for axial positioning; the measuring plates 131 of the two sets of measuring components 13 extend and fit against the side wall of the standard nuclear fuel assembly, and the measurement data under the bottom support posture of the standard nuclear fuel assembly is read as a calibration reference to calibrate the measurement origin of the measuring component 13; the nuclear fuel assembly 6 to be measured is hoisted into the underwater measuring mechanism 1, and the nuclear fuel assembly 6 to be measured is placed on the support component 14 for axial positioning; the measuring plates 131 of the three sets of measuring components 13 of the nuclear fuel assembly to be measured extend and fit against the side wall of the standard nuclear fuel assembly. The sidewall of the nuclear fuel assembly 6 under test is closed, and the deformation data of the bottom support posture of the nuclear fuel assembly 6 under test is read. The host computer 3 performs data fitting and three-dimensional deformation model reconstruction on the deformation data to intuitively display the deformation of the nuclear fuel assembly 6 under test when the bottom support posture is displayed. The support plate 141 of the support component 14 is lowered, the top of the nuclear fuel assembly 6 under test is subjected to force, and the clamping component 12 clamps the nuclear fuel assembly 6 under test to achieve its radial positioning and clamping, and reads the deformation data of the top suspension posture of the nuclear fuel assembly 6 under test. The host computer 3 performs data fitting and three-dimensional deformation model reconstruction on the deformation data to intuitively display the deformation of the nuclear fuel assembly 6 under test when the top suspension posture is displayed. The measuring component 13 and the clamping component 12 are reset, the nuclear fuel assembly 6 under test is lifted away, and the measurement ends.

[0103] Example 3

[0104] like Figure 16 As shown, when the cross-section of the nuclear fuel assembly 6 to be tested is hexagonal, and the underwater measuring mechanism 1 includes two sets of measuring components 13 in the same measuring cross-section, the two sets of measuring components 13 are arranged at 60°, and the positioning surfaces of the measuring components 13 and the clamping components 12 are facing each other. The two sets of measuring components 13 are used to measure the deformation dimensions of two adjacent surfaces in the same cross-section of the hexagonal nuclear fuel assembly 6 to be tested. After three measurements, the data information of three adjacent corners of the hexagon is obtained. Based on the known side length of the cross-section of the nuclear fuel assembly 6 to be tested, the positions of the other two surfaces can be determined. Combined with the digital fitting method, the overall deformation data of the measuring cross-section can be obtained. The measurement process in this embodiment is the same as that in Embodiment 1, and will not be repeated here.

[0105] Example 4

[0106] like Figure 17As shown, when the cross-section of the nuclear fuel assembly 6 under test is hexagonal, and the underwater measuring mechanism 1 includes three sets of measuring components 13 in the same measuring cross-section, adjacent measuring components 13 in the three sets of measuring components 13 are distributed along a 60° angle. These three sets of measuring components 13 are used to measure the deformation dimensions of three opposite surfaces in the same cross-section of the hexagonal nuclear fuel assembly 6 under test. Four angular information of the nuclear fuel assembly can be obtained through two measurements. Based on the known side length of the nuclear fuel assembly cross-section, combined with a digital fitting method, the overall deformation data of the measuring cross-section can be obtained. The measurement process in this embodiment is the same as in Embodiment 1, and will not be repeated here.

[0107] This invention is applicable to underwater measurement of nuclear fuel assembly deformation in high-level radioactive environments, solving the problems of difficulty in manual measurement of nuclear fuel assembly deformation and the risk of nuclear exposure, as well as the difficulty in guaranteeing the accuracy of deformation results by non-contact measurement. This invention employs contact measurement, effectively avoiding interference from environmental factors such as insufficient underwater lighting, temperature field changes, and turbulence, ensuring measurement accuracy. The deformation measurement of the nuclear fuel assembly between its top-suspended and bottom-supported positions is achieved through the lifting and lowering adjustment of the support component 14. By placing the power unit below the water surface 8 and arranging multiple measuring components 13, frequent lifting and lowering of the measuring sensors during measurement is avoided, simplifying the structure of the measuring device and facilitating inspection and maintenance. The contact between the measuring plate 131 and the surface of the nuclear fuel assembly overcomes the influence of single-point indentation features on measurement accuracy. The simultaneous operation of multi-section, multi-directional measuring sensors greatly improves measurement efficiency.

[0108] Of course, there may be other embodiments of this utility model. Without departing from the spirit and essence of this utility model, those skilled in the art can make various corresponding changes and modifications based on this utility model, but these corresponding changes and modifications should all fall within the protection scope of the appended claims of this utility model.

Claims

1. A nuclear fuel assembly deformation underwater measuring mechanism characterized by, include: frame; A clamping component is disposed on the upper part of the frame and has a clamping position and a releasing position relative to the frame. The clamping component is radially positioned and clamps the nuclear fuel assembly to be tested. A support component is disposed at the bottom of the frame and has a supporting position and a retracted position relative to the frame. The support component axially positions the nuclear fuel assembly under test and changes the stress state of the nuclear fuel assembly under test. as well as Multiple measuring components are respectively installed on corresponding rack interfaces along the height direction of the nuclear fuel assembly under test. The multiple measuring components simultaneously measure the deformation data of the nuclear fuel assembly under test in multiple sections and directions.

2. The nuclear fuel assembly deformation measurement mechanism under water according to claim 1, wherein The measuring component includes a measuring plate, a connector, and a displacement sensor. The displacement sensor is connected to the measuring plate via the connector. The measuring rod of the displacement sensor extends adaptively via an elastic element. The measuring plate achieves contact measurement by adaptively fitting the nuclear fuel assembly under test through a slight angular deformation along the horizontal direction.

3. The nuclear fuel assembly deformation measurement mechanism under water according to claim 2, wherein The measuring component also includes a retraction drive and a retraction link. The retraction link is connected to the retraction drive and the connecting member, respectively. The retraction drive drives the retraction link to extend or retract to control the contact or separation of the measuring plate from the nuclear fuel assembly under test.

4. The nuclear fuel assembly deformation measurement mechanism under water according to claim 2 or 3, characterized by, The measuring component is configured to correspond to the grid and lower tube seat of the nuclear fuel assembly under test, and the measuring plate is in surface contact with the grid and lower tube seat of the nuclear fuel assembly under test for measurement.

5. The nuclear fuel assembly deformation underwater measuring mechanism according to claim 1, wherein The support component includes a support plate, a support spring, a lever, a limit switch, and a fixed plate. The support plate is mounted on the support spring and its upper limit position is limited by a spring limiter. When the support plate is in the upper limit position, the preload of the support spring is less than the weight of the nuclear fuel assembly under test. The limit switch is mounted on the fixed plate. One end of the lever is connected to a power mechanism, and the other end of the lever is connected to the support plate. The power mechanism controls the support plate to switch between the supported position and the retracted position through the lever.

6. The nuclear fuel assembly deformation measurement mechanism under water as claimed in claim 5, wherein The support component also includes a support guide plate and a positioning pin for guiding and radially positioning the nuclear fuel assembly under test, which are respectively disposed on the support plate; the spring limiting member is located on the fixed plate and connected to the support spring.

7. The nuclear fuel assembly deformation underwater measuring mechanism according to claim 1, wherein The clamping component includes a positioning component and a swinging component. The swinging component is located on one side of the nuclear fuel assembly to be tested and is connected to the power mechanism; the positioning component is located on the other side of the nuclear fuel assembly to be tested and is connected to the power mechanism.

8. The nuclear fuel assembly deformation measurement mechanism under water as claimed in claim 7, wherein The positioning component includes a positioning flap and a flipping drive. One end of the flipping drive is connected to the positioning flap, and the flipping drive controls the positioning flap to contact or separate from the nuclear fuel assembly to be tested.

9. The nuclear fuel assembly deformation measurement mechanism under water as claimed in claim 7, wherein, The swinging component includes a swing arm, a connecting rod, and a torsion spring. One end of the swing arm is connected to the torsion spring, and the other end of the swing arm is connected to the power mechanism through the connecting rod. The power mechanism controls the swing arm to be in the clamped position or the released position through the connecting rod.

10. A nuclear fuel assembly deformation measurement apparatus underwater, characterized by, Includes the underwater measuring mechanism as described in any one of claims 1-9.

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