Heating rod helical pitch detection device and detection method for nuclear reactor experiment

Abstract

This invention discloses a heating rod helical pitch detection device for nuclear reactor experiments, which is simple in structure and does not easily damage the heating rod. It includes a guiding structure, a positioning structure, and a pitch measuring structure. The guiding structure defines a measurement space, and its outer surface has a guiding through-hole. The positioning structure is rotatably mounted at one end of the guiding structure and has a positioning part for limiting the end of the heating rod. The pitch measuring structure includes a slider disposed within the guiding through-hole and movable axially along the guiding structure, and a probe that slides radially into the slider along the guiding structure, with its lower end abutting against the surface of the heating rod. Under external force, the guiding structure rotates relative to the positioning structure, causing the probe to hold the heating rod and slide radially relative to the slider along the guiding structure, and also causing the probe to move axially along the guiding structure to obtain the measured helical pitch. A method for detecting the heating rod helical pitch using the above-described heating rod helical pitch detection device is also disclosed.

Description

Technical Field

[0001] This invention relates to the field of thermal experimental research technology in reactor engineering, and in particular to a heating rod helical pitch detection device and detection method for nuclear reactor experiments. Background Technology

[0002] The thermo-hydraulic performance of reactor core fuel assemblies directly affects the safety and economy of reactor operation. To optimize the overall performance of fuel assemblies, the industry has conducted extensive theoretical and experimental research on their thermo-hydraulic characteristics. Among these, the structural dimensions of the experimental heating rods are key parameters characterizing the core geometry and determining the thermo-hydraulic characteristics of the fuel assemblies, which are primarily influenced by the fuel assembly structure. Given the complexity of the flow field within the rod bundle channels, the relevant thermo-hydraulic characteristics of fuel assemblies used for safety assessment are mainly measured experimentally. Fuel elements in reactors are typically rod-shaped. In thermal experiments during fuel development, the outer diameter and length of the heating rods are usually measured. For ribbed or twisted irregular-shaped heating rods, their length, chamfers on the cross-section, and rib height can be detected using conventional methods; however, the pitch of the self-helical structure along the axial direction of the cross-section (i.e., the helical pitch of the self-helical structure heating rod) is usually measured using optical scanning imaging, which is inefficient and costly. When conducting rod bundle-level experiments, all heating rods need to be inspected individually, resulting in high time and economic costs.

[0003] Currently, most devices on the market for measuring helical pitch are designed for helical tubes, screws, propellers, etc. These pitch measuring devices have complex structures and do not involve fuel components, which can easily damage the heating rods and make them unsuitable for detecting pitch of heterogeneous helical components with heating rods featuring helical characteristics. Summary of the Invention

[0004] Therefore, it is necessary to address the above-mentioned shortcomings by providing a heating rod helical pitch detection device and method for nuclear reactor experiments that is simple in structure and does not easily damage the heating rod.

[0005] A heating rod helical pitch detection device for nuclear reactor experiments, wherein the heating rod has at least one helical rib protruding from its side and extending along the axial direction of the heating rod, the heating rod helical pitch detection device comprising: A guide structure is provided, wherein the guide structure has a measuring space for inserting the heating rod, and the outer surface of the guide structure has a guide through hole that extends along the axial direction of the guide structure and communicates with the measuring space; A positioning structure is rotatably disposed at one end of the guide structure, and the positioning structure is provided with a positioning part for limiting the relative rotation of the heating rod and the positioning structure. A pitch measuring structure includes a slider disposed in the guide through hole and capable of reciprocating along the axial direction of the guide structure, and a probe inserted and mounted on the slider and capable of reciprocating along the radial direction of the guide structure, the lower end of the probe being configured to abut against the surface of the heating rod.

[0006] In one embodiment, the outer surface of the guide structure is provided with a first scale mark extending along the axial direction of the guide structure near the guide through hole; the annular side of the positioning structure is provided with a second scale mark extending along the circumferential direction of the positioning structure; and the surface of the probe is provided with a third scale mark extending along the axial direction of the probe.

[0007] In one embodiment, the end of the positioning structure has a through hole that communicates with the measurement space and forms the positioning part; the heating rod passes through the through hole and is fixedly connected to the positioning structure.

[0008] In one embodiment, the inner contour shape of the through hole is adapted to the cross-sectional shape of the heating rod.

[0009] In one embodiment, a groove is formed on each of the two opposite inner sidewalls of the guide hole, and the two ends of the slider are slidably inserted into the two grooves to be confined within the guide hole.

[0010] In one embodiment, the lower end of the probe is curved.

[0011] This invention also discloses a method for detecting the helical pitch of a heating rod used in nuclear reactor experiments. This method employs the aforementioned heating rod helical pitch detection device and includes the following steps: S1. Insert the heating rod into the measuring space of the guide structure and fix the heating rod on the positioning structure; S2. Rotate the guide structure relative to the positioning structure to the target angle, and move the pitch measuring structure along the axial direction of the guide structure to the theoretical pitch measuring position; S3. Adjust the position of the pitch measuring structure near the theoretical pitch measuring position, identify the actual pitch position based on the change in probe height, and calculate the deviation between the actual pitch position and the theoretical pitch measuring position.

[0012] In one embodiment, step S2 includes: S21. Take multiple theoretical pitch measurement positions within the theoretical helical pitch; S22. At each of the theoretical pitch measurement positions, the guide structure is rotated sequentially through the target angle, and then proceeds to step S3.

[0013] In one embodiment, in step S22, the guide structure rotates multiple target angles within a complete rotation cycle.

[0014] In one embodiment, step S3, identifying the actual pitch position near the theoretical pitch measurement position based on the probe height change, includes: S31. At the theoretical pitch measurement position, finely adjust the position of the slider along the axial direction of the guide structure, or finely adjust the rotation angle of the guide structure at the theoretical pitch measurement position, so that the height of the probe reaches the maximum value; S32. When the probe height reaches its maximum value, the position of the probe in the axial direction of the guide structure is the actual pitch position.

[0015] In one embodiment, step S3 is followed by: S4. Calculate the deviation between the actual pitch position and the theoretical pitch measurement position at each measurement location, and take the average value of the deviations at each measurement location as the pitch error.

[0016] The present invention provides a heating rod helical pitch detection device and method for nuclear reactor experiments. It employs a positioning structure to locate the heating rod, ensuring the relative position between the positioning and guiding structures, establishing a helical pitch measurement benchmark, and preventing heating rod displacement during measurement to guarantee the reliability of the measurement structure. By moving the pitch measurement structure to the theoretical measurement position, the height change of the probe is used to detect the pitch location, obtaining the measured helical pitch, and evaluating the heating rod based on the deviation. The device features a reliable and simple structural design, is not prone to damaging the heating rod, and can measure the helical pitch of heating rods with helical structures. Attached Figure Description

[0017] To more clearly illustrate the technical solution of the present invention, the present invention will be further described below in conjunction with the accompanying drawings and embodiments. It should be understood that the following drawings only show some embodiments of the present invention and should not be considered as a limitation of the scope. For those skilled in the art, other related drawings can be obtained from these drawings without creative effort. In the drawings: Figure 1 This is a schematic diagram of the heating rod structure in one embodiment of the present invention; Figure 2 This is a schematic diagram of the structure of the heating rod insertion heating rod helical pitch detection device in one embodiment of the present invention; Figure 3 for Figure 2 A partially enlarged structural diagram of part A in the illustrated embodiment; Figure 4This is a schematic diagram of the heating rod helical pitch detection device in one embodiment of the present invention; Figure 5 This is a flowchart of a helical pitch detection method in one embodiment of the present invention. Detailed Implementation

[0018] To provide a clearer understanding of the technical features, objectives, and effects of this invention, specific embodiments are now described in detail with reference to the accompanying drawings. In the following description, it should be understood that the orientations or positional relationships indicated by terms such as "front," "rear," "upper," "lower," "left," "right," "longitudinal," "horizontal," "vertical," "horizontal," "top," "bottom," "inner," "outer," "head," and "tail" are based on the orientations or positional relationships shown in the accompanying drawings, and are constructed and operated in a specific orientation. They are only for the convenience of describing this technical solution and do not indicate that the device or element referred to must have a specific orientation; therefore, they should not be construed as limitations on this invention.

[0019] It should also be noted that, unless otherwise explicitly specified and limited, terms such as "installation," "connection," "linking," "fixing," and "setting" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. When an component is referred to as being "on" or "below" another component, the component can be located "directly" or "indirectly" on the other component, or there may be one or more intermediary components. The terms "first," "second," "third," etc., are only for the convenience of describing this technical solution and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, features defined with "first," "second," "third," etc., may explicitly or implicitly include one or more of that feature. For those skilled in the art, the specific meaning of the above terms in this invention can be understood according to the specific circumstances.

[0020] In the following description, specific details such as particular system architectures and techniques are set forth for illustrative purposes and not for limitation, in order to provide a thorough understanding of the embodiments of the invention. However, those skilled in the art will understand that the invention can be implemented in other embodiments without these specific details. In other instances, detailed descriptions of well-known systems, apparatuses, circuits, and methods are omitted so as not to obscure the description of the invention with unnecessary detail.

[0021] Example 1 Please combine Figures 1-4This invention discloses a heating rod helical pitch detection device for nuclear reactor experiments that is simple in structure and does not easily damage the heating rod. The heating rod 10 can be a bundle of ribs, a twisted fuel, or other heating rods with helical structural features. At least one helical rib 20 is protruding from the side of the heating rod 10 and extends along the axial direction of the heating rod 10. When the number of helical ribs 20 on the circumferential side of the heating rod 10 is greater than 1, multiple helical ribs 20 are uniformly arranged on the circumferential side of the heating rod 10.

[0022] The heating rod helical pitch detection device of this embodiment includes a guide structure 100, a positioning structure 200, and a pitch measuring structure 300. The guide structure 100 is used to rotatably engage with the positioning structure 200 and limit the axial movement of the pitch measuring structure 300. The positioning structure 200 is used to install and position the heating rod 10 to prevent the heating rod 10 from shifting or rotating during pitch measurement. The pitch measuring structure 300 is used to identify the actual position of the helical structure at the theoretical pitch measurement position. The guide structure 100 is provided with a measuring space 110 for inserting the heating rod 10. Both ends of the guide structure 100 are connected to the measuring space 110. One end forms an insertion port for inserting the heating rod 10, and the other end forms an installation port connected to the positioning structure 200. The outer surface of the guide structure 100 is provided with a guide through hole 120 extending axially along the guide structure 100 and communicating with the measuring space 110. The guide through hole 120 is used to limit the path of the pitch measuring structure 300 moving axially along the guide structure 100. The positioning structure 200 is rotatably disposed at one end of the guide structure 100. That is, the positioning structure 200 and the guide structure 100 can rotate relative to each other under the action of an external force to change the position of the pitch measuring structure 300 on the surface of the heating rod 10, thereby measuring the pitch of the heating rod 10. The positioning structure 200 is provided with a positioning part 210 for limiting the relative rotation between the heating rod 10 and the positioning structure 200, thereby limiting the heating rod 10 by the positioning structure 200 to prevent the heating rod 10 from shifting or rotating during the pitch measurement process. The pitch measuring structure 300 includes a slider 310 disposed within a guide through hole 120 and movable axially along a guide structure 100, and a probe 320 inserted and mounted on the slider 310 and movable radially along the guide structure 100. The lower end of the probe 320 is configured to abut against the surface of the heating rod 10. The slider 310 serves to constrain the probe 320 along the axial direction of the guide structure 100 and prevent the probe 320 from rotating relative to the guide structure 100. The lower end of the probe 320 contacts the surface of the heating rod 10. Similarly, when the guide structure 100 rotates relative to the positioning structure 200, the lower end of the probe 320 moves in a spiral motion along the surface of the heating rod 10. When the lower end of the probe 320 contacts different parts of the heating rod 10, due to the different heights of the different parts of the heating rod 10, the probe 320 will rise and fall radially relative to the slider 310 along the guide structure 100 under the pushing force of the surface of the heating rod 10. In this way, the actual position of the probe 320 can be determined based on the lifting height of the upper end of the probe 320, so as to measure the actual spiral pitch of the heating rod 10.

[0023] When measuring the actual helical pitch of the heating rod 10, the guide structure 100 rotates relative to the positioning structure 200 under the action of external force. During this process, the heating rod 10 remains stationary under the restriction of the positioning structure 200. As the guide structure 100 rotates, the probe 320 is made to hold the heating rod 10 and slide radially relative to the slider 310 along the guide structure 100 through the cooperation between the slider 310 and the inner wall of the guide through hole 120. The probe 320 is also made to move axially along the guide structure 100 so that when the probe 320 rises to the highest position near the theoretical pitch measurement position, the actual helical pitch of the helical pitch measurement can be obtained according to the axial position of the probe 320 in the guide structure 100. In this embodiment, with the fixed positioning structure and heating rod, the guide structure is rotated to the target angle, and the pitch measuring structure is moved to the theoretical pitch measuring position (i.e., the measuring point). Then, the position of the pitch measuring structure 300 is adjusted by fine-tuning the angle of the guide structure or fine-tuning the axial position of the pitch measuring structure along the guide structure (both fine-tuning the angle of the guide structure and fine-tuning the axial position of the pitch measuring structure can achieve the purpose of adjusting the position of the pitch measuring structure 300). When the probe 320 rises to its maximum height, the pitch corresponding to the position of the probe 320 in the axial direction of the guide structure 100 is the measured helical pitch of the helical pitch measurement.

[0024] In one embodiment, the guide structure 100 is a cylindrical structure with a cross-sectional outer contour that is circular, square, regular pentagon, regular hexagon, regular octagon, or other regular polygons. The outer surface of the guide structure 100 provides a gripping part when the guide structure 100 rotates. When the cross-sectional outer contour of the guide structure 100 is circular, an anti-slip structure, such as anti-slip texture or anti-slip layer, can also be provided on the outer ring side of the guide structure 100 to prevent slippage when rotating the guide structure 100. The inner contour of the cross-section of the guide structure 100 is circular. Thus, during the rotation of the guide structure 100 relative to the positioning structure 200, it is only necessary to ensure that the distance from the top of the spiral rib 20 to the axis of the heating rod 10 is less than the radius of the inner side of the guide structure 100 to prevent the inner wall of the guide structure 100 from scraping against the spiral rib 20 and avoiding damage to the spiral rib 20. Preferably, in this embodiment, the guide structure 100 is a circular tube structure with uniform wall thickness.

[0025] In another embodiment, the guide structure 100 may also be a semi-enclosed structure with an opening on the side. For example, the cross-section of the guide structure 100 is a C-shaped structure or a U-shaped structure, and the guide structure 100 extends in the direction close to the positioning structure 200. In this case, it is only necessary to ensure that a guide through hole can be opened on the guide structure 100, and that the inner side of the guide structure 100 will not interfere with the heating rod when it rotates relative to the heating rod.

[0026] The positioning structure 200 is made of a metal plate of a certain thickness, such as stainless steel. The positioning structure 200 is used to hold the heating rod 10 in place, thereby ensuring the quality of the installation and positioning of the experimental piece (and irregularly shaped heating rods 10). One end of the guide structure 100 is rotatably connected to the positioning structure 200, and the guide structure 100 and the positioning structure 200 are limited along the axial direction of the guide structure 100. This ensures that the guide structure 100 can rotate relative to the positioning structure 200 while preventing the guide structure 100 from falling off the positioning structure 200. In one embodiment, when the guide structure 100 is a cylindrical structure, an annular limiting groove is provided on one end face of the guide structure 100, and a limiting protrusion that can be inserted into the annular limiting groove is provided on the end face of the positioning structure 200 near the guide structure 100. The width of the annular limiting groove on the side near the limiting protrusion is smaller than the width of the annular limiting groove on the side away from the limiting protrusion. The outer contour shape of the limiting protrusion is adapted to the inner contour shape of the annular limiting groove, thereby achieving axial limiting of the guide structure 100 and the positioning structure 200 while allowing relative rotation between them, so as to prevent the positioning structure 200 from falling off the guide structure 100. Of course, the guide structure 100 and the positioning structure 200 can also adopt other matching methods that can simultaneously achieve axial limiting and relative rotation, which will not be described in detail here. In addition, the side of the guide structure 100 adjacent to the positioning structure 200 is in contact with the side of the positioning structure 200 adjacent to the guide structure 100 to prevent external dust and impurities from entering the axial limiting part of the guide structure 100 and the positioning structure 200, thereby causing the guide structure 100 to get stuck and have difficulty rotating.

[0027] In one embodiment, the end of the positioning structure 200 has a through hole that communicates with the measurement space 110 and forms a positioning part 210; the heating rod 10 passes through the through hole and is fixedly connected to the positioning structure 200. By providing a through hole on the positioning structure 200 and fixing the heating rod 10 to the positioning structure 200 after passing through the through hole, the rotation and linear movement of the heating rod 10 can be restricted, preventing the heating rod 10 from shifting or moving during pitch measurement, thereby ensuring the reliability of the measurement results.

[0028] Furthermore, the inner contour shape of the through hole is adapted to the cross-sectional shape of the heating rod 10. In this embodiment, three spiral ribs 20 are evenly arranged along the circumferential direction on the annular side of the heating rod 10, and a herringbone-shaped through hole is provided on the positioning structure 200. The through hole includes three sub-channels, and the included angle between adjacent sub-channels is 120°. During the pitch measurement process, when the end of the heating rod 10 is inserted into the through hole, the three spiral ribs 20 on the heating rod 10 abut against the inner walls of the three sub-channels of the through hole one by one, so as to prevent the heating rod 10 from rotating relative to the positioning structure 200. Since the spiral ribs 20 themselves have a spiral structure, while restricting the rotation of the spiral ribs 20, the spiral ribs 20 are difficult to move relative to the guide structure 100 along the axial direction of the guide structure 100, thereby achieving the limitation of the heating rod 10. When only one spiral rib 20 is provided on the annular side of the heating rod 10, the through hole includes a strip-shaped portion for accommodating the spiral rib 20 and a circular portion located at one end of the strip-shaped portion for accommodating the heating rod 10. In this case, the rotation and axial movement of the heating rod 10 can be restricted by the constraint of the strip-shaped portion.

[0029] In another embodiment, an elastic claw may be provided within the positioning structure 200, and an operating part for opening or closing the elastic claw may be provided on the outside of the elastic claw. Before the heating rod 10 is inserted into the guide structure 100, the elastic claw is opened by operating the operating part. When the end of the heating rod 10 is inserted into the area enclosed by the elastic claw, the elastic claw is closed by operating the operating part, that is, the heating rod 10 is clamped by the elastic claw, thereby limiting the movement of the heating rod 10. In other embodiments, other limiting mechanisms that can restrict the movement of the heating rod 10 may be provided on the positioning structure 200, which will not be described in detail here.

[0030] In one embodiment, a groove 121 is provided on each of the two opposite inner sidewalls of the guide hole 120. The two ends of the slider 310 are slidably inserted into the two grooves 121 to limit the probe 320 within the guide hole 120, thereby limiting the position of the probe 320 in the circumferential direction of the guide structure 100. This allows the probe 320 to follow the rotation of the guide structure 100 and perform a spiral motion relative to the heating rod 10. In other words, the groove 121 is used to install the pitch measuring structure 300 and to position the pitch measuring structure 300. In this embodiment, the slider 310 includes a plate-shaped mounting plate 311 and a sleeve 312 fixed on the upper surface of the mounting plate 311. The mounting plate 311 has a through hole in the middle that communicates with the sleeve 312 and allows the probe 320 to pass through. The lower ring side of the probe 320 is provided with a limiting ring 313. The outer diameter of the limiting ring 313 is larger than the inner diameter of the through hole. Thus, through the cooperation between the limiting ring 313 and the edge of the through hole, and the contact between the lower end of the probe 320 and the surface of the heating rod 10, the probe 320 can be kept on the slider 310 at all times to prevent the probe 320 from falling off the slider 310 and causing the pitch detection to fail.

[0031] In addition, the lower end of the probe 320 is an arc surface. Thus, when the probe 320 moves in a spiral motion relative to the heating rod 10 under the drive of the guide structure 100, the lower end of the probe 320 is in surface contact with the surface of the heating rod 10. This increases the contact area between the lower end of the probe 320 and the heating rod 10, thereby reducing the pressure exerted by the probe 320 on the surface of the heating rod 10, which helps to reduce damage to the surface of the heating rod 10.

[0032] In another embodiment, the sleeve 312 is provided with an elastic element, and the probe has a slot on its side. The elastic element has a spring foot that can be inserted into the slot. The spring foot abuts against the lower inner wall of the slot and pushes the probe downward so that the lower end of the probe is always in close contact with the surface of the heating rod, thereby ensuring the reliability of evaluating the position of the pitch measurement structure by the height of the probe extending out of the sleeve.

[0033] In one embodiment, the outer surface of the guide structure 100 is provided with a first scale mark 130 extending axially along the guide structure 100 near the guide through hole 120; the annular side of the positioning structure 200 is provided with a second scale mark 220 extending circumferentially along the positioning structure 200; and the surface of the probe 320 is provided with a third scale mark 330 extending axially along the probe 320. Further, the slider 310 is provided with a first reference mark 314 that cooperates with the first scale mark 130 to read the measured helical pitch. For example, the annular side of the sleeve 312 is provided with a protrusion corresponding to the first scale mark 130 to form the first reference mark 314. The guide structure 100 is provided with a second reference mark 140 near the second scale mark 220 for reading the rotation angle of the guide structure 100. The second reference mark 140 is also a scale mark. Through the cooperation of the second scale mark 220 and the second reference mark 140, the circumferential rotation angle of the guide structure 100 can be quantified. The top of the sleeve 312 has a third reference mark 340 that cooperates with the third scale mark 330 to read the rising height of the probe 320. The reading of the third scale mark 330 gradually increases in the direction from the upper part of the probe 320 to the lower part of the probe 320. In this way, by setting the first scale mark 130, the measured helical pitch of the heating rod 10 can be read; by using the second scale mark 220, the rotation angle of the guide structure 100 relative to the positioning structure 200 can be controlled, so that the guide structure 100 rotates relative to the positioning structure 200 by a target angle; by using the third scale mark 330 to read the rising height of the probe 320, it is possible to determine whether the probe 320 has reached the highest position, and when the probe 320 reaches the highest position, the reading of the first scale mark 130 is read to obtain the measured helical pitch.

[0034] Example 2 Please combine Figures 1-5This embodiment discloses a method for detecting the helical pitch of heating rods used in nuclear reactor experiments. It employs the heating rod helical pitch detection device from Embodiment 1. The specific structure of the heating rod helical pitch detection device can be found in the relevant description of Embodiment 1, and will not be repeated here. The helical pitch detection method includes the following steps: S1. Insert the heating rod 10 into the measuring space 110 of the guide structure 100 and fix the heating rod 10 on the positioning structure 200 to achieve positioning of the heating rod 10. During the process of inserting the heating rod 10 into the measuring space 110 and fixing it, the lower end of the probe 320 should abut against the surface of the heating rod 10 to achieve the cooperation between the heating rod 10 and the probe 320.

[0035] S2. Rotate the guide structure 100 relative to the positioning structure 200 to the target angle, and move the pitch measuring structure 300 along the axial direction of the guide structure 100 to the theoretical pitch measuring position. During this process, one hand can hold the positioning structure 200 to keep the positioning structure 200 and the heating rod 10 fixed, while the other hand holds the guide structure 100 and rotates it. When rotating the guide structure 100, the position of the pitch measuring structure 300 along the axial direction of the guide structure 100 must remain unchanged. Subsequently, keeping the positioning structure 200, the heating rod 10, and the guide structure fixed, adjust the position of the pitch measuring structure 300 along the axial direction of the guide structure 100 to the theoretical pitch measuring position. In this embodiment, the guide structure 100 can be rotated to the target angle first, and then the probe 320 can be moved along the axial direction of the guide structure 100 to the theoretical pitch measuring position; alternatively, the probe 320 can be moved along the axial direction of the guide structure 100 to the theoretical pitch measuring position first, and then the guide structure 100 can be rotated to the target angle. Furthermore, when rotating the guide structure 100, the position of the probe along the axial direction of the guide structure must remain unchanged, and when moving the axial position of the probe, the position of the guide structure relative to the positioning structure and the heating rod must remain unchanged.

[0036] Step S2 includes: S21. Take multiple theoretical pitch measurement positions within the theoretical helical pitch; S22. At each theoretical pitch measurement position, the guide structure 100 is rotated through the target angle in sequence, and then proceeds to step S3.

[0037] In step S22, the guide structure 100 rotates multiple target angles within one complete rotation cycle, that is, it rotates through multiple target angles within a 360° range.

[0038] Specifically, the target angle is calculated using the following formula: ; in, The target angle is the required rotation angle between the positioning structure 200 and the guide structure 100. To determine the number of measurement positions to be selected within a pitch, when the heating rod 10 has only one spiral rib 20, the value of n can be freely selected according to the actual situation. When the heating rod 10 has multiple spiral ribs 20, n is the number of spiral ribs 20 on the surface of the heating rod 10. In other words, in this embodiment, the number of measurement points can be selected according to usage requirements within the same pitch.

[0039] The theoretical pitch measurement position is calculated according to the following formula: ; in, The distance between two adjacent theoretical pitch measurement positions is P, where P is the theoretical helical pitch. This refers to the planned number of measurement positions to be selected within a pitch. The theoretical pitch measurement position is the location of the measurement point, which can be based on the 0 mark (marked by the first graduation 130), the initial measurement position, or the axial position corresponding to the previous measurement point, with an interval length... The location.

[0040] S3. Adjust the position of the pitch measuring structure 300 near the theoretical pitch measuring position, identify the actual pitch position based on the height change of the probe 320, and calculate the deviation between the actual pitch position and the theoretical pitch measuring position.

[0041] In step S3, the position of the pitch measuring structure 300 is adjusted near the theoretical pitch measurement position, and the actual pitch position is identified based on the height change of the probe 320, including: S31. Fine-tune the position of the slider along the axial direction of the guide structure 100 at the theoretical pitch measurement position, or fine-tune the rotation angle of the guide structure 100 at the theoretical pitch measurement position, so that the height of the probe 320 reaches its maximum value. That is to say, in this embodiment, the position of the pitch measurement structure 300 will change in both ways, either by fine-tuning the rotation angle of the guide structure 100 or by fine-tuning the position of the slider along the axial direction of the guide structure 100 (the former moves the pitch measurement structure 300 by the guide structure 100, while the latter acts directly on the pitch measurement structure 300).

[0042] S32. When the height of probe 320 reaches its maximum value, the position of probe 320 in the axial direction of guide structure 100 is the actual position of the pitch.

[0043] Specifically, when probe 320 rises to its maximum height, its position along the axial direction of guide structure 100 is the actual pitch position. To raise probe 320 to its maximum height, guide structure 100 can be rotated. During this process, guide structure will drive slider and probe to move along the axial direction of guide structure. Simultaneously, probe slides radially relative to slider along guide structure. At this time, the change in reading corresponding to the third scale mark 330 on probe 320 can be used to determine whether probe 320 has risen to its maximum height. That is, when the reading corresponding to the third scale mark 330 reaches its peak, probe 320 has risen to its maximum height. By observing the third scale mark 330 on the surface of probe 320, the actual pitch position is when probe 320 is at its highest position (determined by the scale reading on the surface of probe 320). Record the axial scale of guide structure 100 at this position of probe 320 (i.e., the reading of the first scale mark 130) to obtain the measured helical pitch. The deviation between this measured pitch and the theoretically calculated pitch position is the pitch error.

[0044] Alternatively, to raise the probe 320 to its maximum height, the position of the slider along the axial direction of the guide structure 100 can be finely adjusted. Specifically, while keeping the guide structure, positioning structure, and heating rod stationary, the slider is pulled, causing it to move axially within the guide hole along the guide structure. During this process, the probe moves relative to the heating rod under the influence of the slider. Due to the uneven surface of the heating rod, the probe will rise or fall. When the probe is at its highest position, the axial scale of the guide structure 100 at this position is recorded to obtain the measured helical pitch.

[0045] In addition, step S3 includes: S4. Calculate the deviation between the actual pitch position and the theoretical pitch measurement position at each measurement location, and take the average value of the deviations at each measurement location as the pitch error. In other words, within one helical pitch, take the average value of the deviations between the actual pitch position and the theoretical pitch measurement position at each measurement point as the pitch deviation of the screw pitch.

[0046] The following examples illustrate the specific process of the helical pitch detection method.

[0047] Assuming the existing heating rod 10 has a helical pitch of 360mm and three helical ribs 20 are evenly distributed circumferentially, if three positions are selected along the axial direction of the guide structure 100 for pitch measurement, then the guide structure 100 needs to rotate relative to the positioning structure 200 by the following angle: α = 360 / 3 = 120°.

[0048] Starting from the end spiral portion near the positioning structure 200, the distance between adjacent measurement points is: d=360 / 3=120mm.

[0049] Let the pitch error at each point be δd k , the δd k If the distance between the actual pitch position and the theoretical pitch measurement position at each measurement point is given, then the final pitch measurement error is: Where k is the number of measurements, δd1 is the pitch error of the first measurement point, δd2 is the pitch error of the second measurement point, and δd3 is the pitch error of the third measurement point.

[0050] For the example above, the actual measurement procedure is as follows: After installing the heating rod 10 onto the positioning structure 200, rotate the cylinder sequentially by 0°, 120°, and 240° around 120mm in the axial direction of the guide structure 100. Measure and calculate the deviation between the actual pitch position and the theoretical pitch measurement position. Measurements are taken at 0°, 120°, and 240° because the heating rod 10 has three helical ribs 20 on its surface. The three angles are measured for each of the three helical ribs 20. The theoretical pitch measurement position for each of the three helical ribs 20 is 120mm. Fine-tune the angle of the guide structure 100 or the axial position of the slider at the corresponding angles so that the position of the probe 320 in the axial direction of the guide structure 100 when the probe 320 rises to its maximum height is the actual pitch position. It should be noted that when fine-tuning the guide structure 100° angle or the slider axial position, the guide structure 100° angle can be fine-tuned clockwise or the slider axial position can be moved away from the positioning structure, or the guide structure 100° angle can be fine-tuned counterclockwise or the slider axial position can be moved closer to the positioning structure. The position that is closer to the theoretical pitch measurement position when the probe 320 rises to its maximum height is taken as the actual pitch position.

[0051] After completing the pitch measurement at one measurement point, the average of the errors obtained from three measurements is taken as δd1. The guide structure 100 is rotated to move the probe 320 along the axial direction of the guide structure 100. This process is repeated at approximately 240mm and 360mm, while simultaneously rotating the guide structure 100 to measure the pitch error at that measurement point. Finally, the pitch error is calculated... This refers to the pitch error of the heating rod within this section of the spiral.

[0052] The heating rod helical pitch detection device and method for nuclear reactor experiments of the present invention uses a positioning structure 200 to position the heating rod 10, ensuring the relative position between the positioning structure 200 and the guide structure 100, establishing a helical pitch measurement benchmark, and avoiding displacement of the heating rod 10 during the measurement process to ensure the reliability of the measurement structure. When the pitch measurement structure 300 moves at the theoretical measurement position, the height change of the probe 320 is used to detect the pitch position, obtain the measured helical pitch, and evaluate the heating rod based on the deviation. It adopts a reliable structural design, is simple in structure, and is not easy to damage the heating rod 10, and can realize the measurement of the helical pitch of the heating rod 10 with helical structure features.

[0053] It is understood that the above embodiments only illustrate preferred embodiments of the present invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can freely combine the above technical features without departing from the concept of the present invention, and can also make several modifications and improvements, all of which fall within the protection scope of the present invention. Therefore, all equivalent transformations and modifications made with respect to the scope of the claims of the present invention should fall within the scope of the claims of the present invention.

Claims

1. A heating rod helical pitch detection device for nuclear reactor experiments, wherein at least one helical rib (20) extending axially along the side of the heating rod (10) is provided, characterized in that, The heating rod helical pitch detection device includes: A guide structure (100) is provided with a measuring space (110) for inserting the heating rod (10), and a guide through hole (120) is provided on the outer surface of the guide structure (100) extending axially along the guide structure (100) and communicating with the measuring space (110). A positioning structure (200) is rotatably disposed at one end of the guide structure (100), and the positioning structure (200) is provided with a positioning part (210) for limiting the relative rotation of the heating rod (10) and the positioning structure (200). The pitch measuring structure (300) includes a slider (310) disposed in the guide through hole (120) and movable axially along the guide structure (100), and a probe (320) inserted and mounted on the slider (310) and movable radially along the guide structure (100). The lower end of the probe (320) is configured to abut against the surface of the heating rod (10).

2. The heating rod helical pitch detection device according to claim 1, characterized in that, The outer surface of the guide structure (100) is provided with a first scale mark (130) extending along the axial direction of the guide structure (100) near the guide through hole (120); the circumferential side of the positioning structure (200) is provided with a second scale mark (220) extending along the circumferential direction of the positioning structure (200); the surface of the probe (320) is provided with a third scale mark (330) extending along the axial direction of the probe (320).

3. The heating rod helical pitch detection device according to claim 1, characterized in that, The end of the positioning structure (200) is provided with a through hole that communicates with the measuring space (110) and forms the positioning part (210); the heating rod (10) passes through the through hole and is fixedly connected to the positioning structure (200).

4. The heating rod helical pitch detection device according to claim 3, characterized in that, The inner contour shape of the through hole is adapted to the cross-sectional shape of the heating rod (10).

5. The heating rod helical pitch detection device according to claim 1, characterized in that, Each of the two opposite inner sidewalls of the guide hole (120) has a groove (121), and the two ends of the slider (310) are slidably inserted into the two grooves (121) to be confined within the guide hole (120).

6. The heating rod helical pitch detection device according to claim 1, characterized in that, The lower end of the probe (320) is curved.

7. A method for detecting the pitch of a heating rod helix in a nuclear reactor experiment, implemented using the heating rod helix pitch detection device according to any one of claims 1-6, characterized in that, Includes the following steps: S1. Insert the heating rod (10) into the measuring space (110) of the guide structure (100) and fix the heating rod (10) on the positioning structure (200); S2. Rotate the guide structure (100) relative to the positioning structure (200) to the target angle, and move the pitch measuring structure (300) along the axial direction of the guide structure (100) to the theoretical pitch measuring position; S3. Adjust the position of the pitch measuring structure (300) near the theoretical pitch measuring position, identify the actual pitch position based on the height change of the probe (320), and calculate the deviation between the actual pitch position and the theoretical pitch measuring position.

8. The method for detecting the helical pitch of a heating rod according to claim 7, characterized in that, Step S2 includes: S21. Take multiple theoretical pitch measurement positions within the theoretical helical pitch; S22. At each of the theoretical pitch measurement positions, the guide structure (100) is rotated sequentially through the target angle and then proceeds to step S3.

9. The method for detecting the helical pitch of a heating rod according to claim 8, characterized in that, In step S22, the guide structure (100) rotates multiple target angles within one complete rotation cycle.

10. The method for detecting the helical pitch of a heating rod according to claim 9, characterized in that, In step S3, identifying the actual pitch position near the theoretical pitch measurement position based on the height change of the probe (320) includes: S31. At the theoretical pitch measurement position, fine-tune the position of the slider along the axial direction of the guide structure (100), or fine-tune the rotation angle of the guide structure (100) at the theoretical pitch measurement position, so that the height of the probe (320) reaches the maximum value. S32. When the height of the probe (320) reaches its maximum value, the position of the probe (320) in the axial direction of the guide structure (100) is the actual position of the pitch.

11. The method for detecting the helical pitch of a heating rod according to claim 10, characterized in that, Step S3 is followed by: S4. Calculate the deviation between the actual pitch position and the theoretical pitch measurement position at each measurement location, and take the average value of the deviations at each measurement location as the pitch error.

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