Measurement System and Method for Length Variation of Spent Fuel Components in Nuclear Power Plants

Abstract

This invention discloses a system and method for measuring the length variation of spent fuel-related components in nuclear power plants. The system includes a measuring frame, a measuring probe for acquiring images of the observation window and reference positions, and a controller electrically connected to the measuring probe. The measuring frame includes a frame body, a housing, a measuring scale, and a temporary storage tube for temporarily storing related components or calibration tubes. The housing, measuring scale, and temporary storage tube are mounted side-by-side on the frame body. The housing has a receiving space for accommodating related components or calibration tubes and has at least one observation window with a measuring hole for exposing a portion of the related components or calibration tubes. The measuring scale is adjacent to the housing and also has at least one reference position corresponding to the observation window. This application enables high-precision underwater measurement of the length variation of related components.

Description

Technical Field

[0001] This invention relates to the field of nuclear power technology, and in particular to a system and method for measuring the length variation of spent fuel-related components in a nuclear power plant. Background Technology

[0002] Spent fuel assemblies operate within the reactor core under conditions of high temperature, high pressure, strong neutron radiation, corrosion, erosion, and hydraulic vibration. After a certain period of burnup, these assemblies undergo deformation, such as length changes (expansion and elongation). This deformation reflects the degree of spent fuel combustion and serves as a basis for assessing the core condition. Therefore, it is necessary to periodically measure the length changes of these assemblies.

[0003] Generally, after a major overhaul, it is necessary to inspect the length changes of relevant components. However, since the tank is full of water after the overhaul, measurements of spent fuel must be taken underwater, which affects the accuracy of the measurements. Furthermore, due to the considerable length of the relevant components, it is difficult to accurately measure their overall length underwater, and the overall length change has a large numerical error, making it difficult to guarantee the accuracy of the measurements. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a system for measuring the length change of spent fuel-related components in a nuclear power plant and a method for measuring the length change.

[0005] The technical solution adopted by the embodiments of this application to solve its technical problem is:

[0006] A length variation measurement system for spent fuel-related components in a nuclear power plant is constructed for measuring the length variation of the related components and calibration tubes to obtain length variation data of the related components. The system includes a measuring frame, which comprises:

[0007] The frame is designed to be longitudinal;

[0008] A receiving component is mounted on the frame and extends in a direction parallel to the frame. The receiving component has a receiving space for receiving the relevant components or the calibration tube, and the receiving component is provided with at least one observation window for exposing a measuring hole of part of the relevant components or the calibration tube.

[0009] A measuring scale is mounted on the frame and extends in a direction parallel to the frame, and is adjacent to the receiving component. The measuring scale has at least one reference position corresponding to the observation window.

[0010] A temporary storage tube is used to temporarily store the relevant components or the calibration tube. The temporary storage tube is installed on the frame and extends in a direction parallel to the frame.

[0011] A measuring probe is used to acquire images of the observation window and the reference position; and

[0012] The controller is electrically connected to the measuring probe.

[0013] In some embodiments, the receiving component includes a receiving body and a guide member. The guide member is in the shape of a trumpet-shaped cylinder, and the constricted end of the guide member is connected to the top end of the receiving body. The receiving body is longitudinally elongated, hollow inside to define the receiving space, and is connected to the guide member.

[0014] In some embodiments, the number of observation windows and reference positions are both three, and the three observation windows correspond to the three measurement holes on the relevant components, respectively.

[0015] In some embodiments, the receiving space is an elongated receiving groove formed by the inward indentation of the side wall of the receiving member near the measuring scale, and the extending direction of the receiving groove is parallel to the extending direction of the frame.

[0016] In some embodiments, the opening of the receiving slot is located close to the measuring scale, and the measuring scale has multiple spaced graduation lines on its side away from the frame, with each graduation line being at a different distance from the reference position.

[0017] In some embodiments, at least one reference groove is formed on the side of the measuring scale near the housing, the opening of the reference groove faces the observation window, and the reference position is located at the top or bottom of the reference groove.

[0018] In some embodiments, the measuring frame further includes at least one probe mounting bracket for placing the measuring probe, the probe mounting bracket being disposed on the frame and corresponding to the observation window.

[0019] In some embodiments, the measuring probe includes a housing, a limiting member is provided at the bottom of the housing, and a limiting hole corresponding to the limiting member is formed on the probe mounting bracket, wherein the limiting member is limited within the limiting hole.

[0020] A method for measuring the length variation of spent fuel-related components in a nuclear power plant is constructed and applied to the length variation measurement system for spent fuel-related components in a nuclear power plant described in any of the foregoing embodiments. The method for measuring the length variation of spent fuel-related components in a nuclear power plant includes:

[0021] Step S1: Place the measuring frame and the measuring probe underwater, and place the calibration tube inside the housing;

[0022] Step S2: The controller controls the measuring probe to acquire images of the observation window and the reference position, and obtains the measurement data of the calibration tube;

[0023] Step S3: Transfer the calibration tube into the temporary storage tube and place the relevant components into the housing;

[0024] Step S4: The controller controls the measuring probe to acquire images of the observation window and the reference position, and obtains the measurement data of the relevant components;

[0025] Step S5: Obtain the length change data of the relevant components based on the measurement data of the calibration tube and the measurement data of the relevant components.

[0026] In some embodiments, step S2 includes:

[0027] Step S21: The controller controls the measuring probe to acquire images of the observation window and the reference position;

[0028] Step S22: Obtain the distance from the top of the measuring hole of the calibration tube to the reference position and the distance from the bottom of the measuring hole to the reference position, respectively;

[0029] Step S23: Repeat steps S21 and S22 at least twice, and take the average value of the distance from the top of the measuring hole of the calibration tube to the reference position, and take the average value of the distance from the bottom of the measuring hole of the calibration tube to the reference position to obtain the measurement data of the calibration tube.

[0030] Step S4 includes:

[0031] Step S41: The controller controls the measuring probe to acquire images of the observation window and the reference position;

[0032] Step S42: Obtain the distances from the top and bottom of the measuring hole of the relevant component to the reference position;

[0033] Step S43: Repeat steps S41 and S42 at least twice, and average the distance from the top of the measuring hole of the relevant component to the reference position, and average the distance from the bottom of the measuring hole of the relevant component to the reference position to obtain the measurement data of the relevant component.

[0034] In some embodiments, the method further includes step S0: obtaining the factory data of the calibration tube;

[0035] Step S6: Obtain the scaling factor based on the measurement data of the calibration tube and the factory data; obtain the actual data of the relevant components based on the measurement data of the relevant components and the scaling factor;

[0036] The scaling factor is calculated using Formula 1:

[0037]

[0038] Where k is the scaling factor;

[0039] k' is a constant;

[0040] b represents the measurement data from the calibration tube;

[0041] 'a' represents the factory data for the calibration tube.

[0042] Implementing the embodiments of the present invention has at least the following beneficial effects:

[0043] This application, by setting up a measuring frame and measuring probe, enables underwater measurement of the length changes of relevant components, avoiding the radiation hazards associated with manual measurement by operators. By selecting different measuring probes, underwater measurements of varying accuracy can be performed, achieving high-precision underwater measurement of the length changes of relevant components. This application, by incorporating a temporary storage tube and a receiving component, allows the measuring frame to simultaneously accommodate two tubes. Before measuring the relevant components, the calibration tube is measured to obtain reference data. Then, the calibration tube is temporarily stored in the temporary storage tube, and the relevant components within the receiving component are measured, thereby obtaining the length changes of the relevant components. This ensures environmental consistency during measurement, reduces errors caused by measurement variables, and further improves measurement accuracy. Attached Figure Description

[0044] The present application will be further described below with reference to the accompanying drawings and embodiments. In the accompanying drawings:

[0045] Figure 1 This is a partial structural diagram of the measuring frame in a nuclear power plant spent fuel-related component length variation measuring system according to an embodiment of this application;

[0046] Figure 2 yes Figure 1 A magnified view of part P in the diagram;

[0047] Figure 3 yes Figure 2 A schematic diagram of the structure of part P shown from another angle;

[0048] Figure 4 yes Figure 1 A schematic diagram of the cross-sectional structure of the housing and measuring scale in the reference groove;

[0049] Figure 5 This is a partial structural schematic diagram of the aperture adjustment component of the measuring probe in a nuclear power plant spent fuel-related component length change measuring system according to an embodiment of this application;

[0050] Figure 6 This is a schematic diagram of the controller's module connections;

[0051] Figure 7 This is a flowchart of the steps of a method for measuring the length change of spent fuel-related components in a nuclear power plant according to an embodiment of this application;

[0052] Figure 8 yes Figure 7 The flowchart of step S2 in the text;

[0053] Figure 9 yes Figure 7 The flowchart for step S4 in the process;

[0054] Figure 10 This is a diagram showing the correspondence of measurement data for relevant components in one embodiment;

[0055] Figure label:

[0056] 1-Measuring frame; 10-Frame body; 11-Connecting hole; 20-Receiving component; 21-First receiving body; 211-Observation window; 212-Receiving slot; 22-First guide; 30-Measuring scale; 31-Reference slot; 300-Reference position; 301-First reference position; 302-Second reference position; 303-Third reference position; 40-Probe mounting bracket; 41-Mounting bracket body; 411-Limiting hole; 42-Guide wall; 50-Temporary storage tube; 51-Second receiving body; 52-Second guide; 60-Abutment bracket;

[0057] 2-Related components; 201-Measuring hole; 2011-First measuring hole; 2012-Second measuring hole; 2013-Third measuring hole;

[0058] 4-Aperture adjustment assembly; 401-Aperture motor; 402-Aperture motor bushing; 403-Aperture adjustment gear; 404-Aperture adjustment spring; Aperture clamping nut. Detailed Implementation

[0059] To provide a clearer understanding of the technical features, objectives, and effects of this application, the specific embodiments of this application 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," "vertical," "horizontal," "bottom," "inner," "further," and "outer" are based on the orientations or positional relationships shown in some of 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 application.

[0060] 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," 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," 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 application can be understood according to the specific circumstances.

[0061] 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 this application. However, those skilled in the art will understand that this application may also be implemented in other embodiments without these specific details. In other instances, detailed descriptions of well-known systems, apparatuses, circuits, and methods have been omitted so as not to obscure the description of this application with unnecessary detail.

[0062] Figures 1 to 6 This paper illustrates a partial structure of a spent fuel-related component length variation measurement system according to an embodiment of this application. It can perform length measurement operations on spent fuel-related components 2 at water levels in the pool.

[0063] Among them, such as Figure 2 and Figure 4As shown, the spent fuel includes multiple related components 2, each of which is arranged in a longitudinally elongated tubular shape, and three measuring holes 201 are spaced apart along the axial direction on the related component 2. Two of the measuring holes 201 are located near the two ends of the related component 2, and the remaining measuring hole 201 is located in the lower middle part of the related component 2.

[0064] The spent fuel related component length change measurement system of this nuclear power plant includes a measuring frame 1, a measuring probe (not shown in the figure), and a controller (not shown in the figure). The measuring frame 1 carries the related component 2 and the measuring probe, enabling the measuring probe to perform underwater measurements on the related component 2. The measuring probe is used for image acquisition to obtain the specific underwater position of a portion of the related component 2, thereby obtaining the length data of the related component 2. The controller is electrically connected to the measuring probe and is used to control the measuring probe to perform image acquisition.

[0065] like Figure 1 and Figure 2 As shown, specifically, the measuring frame 1 includes a frame body 10, a receiving component 20, a measuring scale 30, and a temporary storage tube 50. The frame body 10 is longitudinally arranged. The receiving component 20 is longitudinally arranged and is positioned on the frame body 10 parallel to its extension direction. It forms a receiving space with an open upper end and a closed lower end for receiving related components 2 or calibration tubes. The measuring scale 30 is longitudinally arranged and is positioned on the frame body 10 parallel to its extension direction, adjacent to the receiving component 20, and is used as a measuring ruler to measure the length of related components 2 or calibration tubes at specific locations. The temporary storage tube 50 is also longitudinally arranged, with an open upper end and a closed lower end, and is positioned on the frame body 10 parallel to its extension direction, for temporarily storing related components 2 or calibration tubes.

[0066] See also Figure 3 The housing 20 is provided with at least one observation window 211 for exposing a portion of the relevant component 2 or calibration tube (the portion where the measuring hole 201 is located) within the housing space. The measuring scale 30 has at least one reference position 300 corresponding to the observation window 211. The measuring probe is positioned toward the observation window 211 and the reference position 300, allowing the measuring probe to acquire images of the observation window 211 and the reference position 200 (as well as the relevant component 2 / calibration tube section exposed within the observation window and the measuring hole 201 on the section).

[0067] When it is necessary to measure the length change of the relevant component 2, the calibration tube is first placed inside the housing 20. The controller then controls the measurement probe to acquire images, obtaining data related to the calibration tube section and the measurement holes 201 on the section. The calibration tube is then transferred to the temporary storage tube 50, and one of the relevant components 2 of the spent fuel is placed inside the housing 20. The controller then controls the measurement probe to acquire images, obtaining data related to the relevant component 2 section and the measurement holes 201 on the section. By comparing the acquired data from the calibration tube and the relevant component 2, the length change of the relevant component 2 after combustion can be obtained. Simultaneously, the acquired data from the calibration tube and the relevant component 2 can serve as basic data for evaluating the combustion status of the spent fuel and the core condition.

[0068] This application enables the length measurement of related components 2 to be carried out underwater by setting up a measuring frame 1, a measuring probe, and a controller, thus avoiding the radiation hazards associated with manual measurement by operators.

[0069] This application, by setting a temporary storage tube 50 on the measuring frame 1, allows for the measurement of the calibration tube before measuring the relevant component 2, obtaining reference data. This reference data can then be compared with the data obtained from measuring the relevant component 2 to determine the length change of the relevant component 2. Simultaneously, underwater measurement of the calibration tube ensures environmental consistency between the two measurement processes. This avoids the amplified error in the length change of the relevant component 2 that would occur when comparing data obtained from the surface measurement calibration tube with data obtained from underwater measurement of the relevant component 2, thus ensuring measurement accuracy.

[0070] It is important to understand that a "calibration tube" refers to a tube with the same structure as the related component 2 that has not yet undergone combustion (i.e., is ready for use at the factory). It can be a tube with the same structure as the related component 2 that has not undergone combustion but with different manufacturing materials (and / or processes, etc.), or it can be the related component 2 that has not yet undergone combustion (i.e., is ready for use at the factory).

[0071] It should be understood that the underwater handling and transfer of the calibration tube and related component 2 can both be carried out using existing single-bar transfer tools. Alternatively, the nuclear power plant spent fuel related component length change measurement system constructed in this application may include a robotic arm with the function of handling related component 2 (calibration tube) to perform handling and other operations on related component 2 (calibration tube).

[0072] In some other alternative embodiments, the observation window 211 can also expose all relevant components 2 or calibration tubes (the part where the measuring hole 201 is located) located in the containment space by using transparent materials, increasing the window area, etc.

[0073] like Figure 1 As shown, in this embodiment, there are three observation windows 211, each corresponding to one of the three measuring holes 201 on the relevant component 2. Correspondingly, there are also three reference points 300. By measuring the length data at all the measuring holes 201 of the relevant component 2, more data support can be provided for the evaluation and analysis, improving the accuracy of the evaluation and analysis.

[0074] In this embodiment, the frame 10 has a longitudinally elongated rectangular column structure. It is formed by splicing multiple rectangular plates and is hollow inside to reduce the weight of the measuring frame 1 and facilitate lowering and lifting. Each rectangular plate has numerous through holes of different sizes to further reduce the overall weight. At the same time, some rectangular plates can be spaced apart to further reduce the overall weight.

[0075] Furthermore, the housing 20 and the measuring scale 30 are disposed on the same side wall of the frame 10, and the temporary storage tube 50 is disposed on one of the remaining three side walls of the frame 10, in order to reduce the size of the frame 10.

[0076] In this embodiment, the bottom ends of the frame 10, the receiving component 20, the measuring scale 30, and the temporary storage tube 50 are flush, and the measuring scale 30 is adapted to the height of the frame 10. The receiving component 20 and the temporary storage tube 50 are approximately the same height, slightly higher than the frame 10, and slightly shorter than the length of the relevant component 2 and the calibration tube, so as to facilitate the entry and exit of the relevant component 2 or the calibration tube.

[0077] Both the receiving component 20 and the temporary storage tube 50 include a receiving body and a guide. The receiving body is longitudinally elongated for receiving. The guide is flared and cylindrical, with its constricted end connected to the top of the receiving body for guiding. This facilitates the insertion of the relevant component 2 or calibration tube from the top. The receiving body is longitudinally elongated and hollow inside to define the receiving space, and it communicates with the guide.

[0078] It should be understood that the terms "top" and "bottom" used in this application can be based on the extension direction of the frame 10. Figure 1 In the illustrated embodiment, the guide is located at the top of the receiving body.

[0079] The containment body and guide of containment item 20 are now defined as first containment body 21 and first guide 22, and the containment body and guide of temporary storage tube 50 are defined as second containment body 51 and second guide 52. See also Figure 2 The observation window 211 is formed on the first containment body 21.

[0080] Specifically, the first receiving body 21 includes multiple pipe segments, each segment spaced apart, with the gap between adjacent segments serving as an observation window 211. The first receiving body 21 and the measuring scale 30 are both fitted abutting against the side wall of the frame 10. The second receiving body 51 is a longitudinally elongated single pipe, mounted on the frame 10 via at least two support structures, with its side wall spaced apart from the side wall of the frame 10.

[0081] In some other alternative embodiments, the first receiving body 21 can also be configured as a longitudinally elongated single tube, with an opening provided on the first receiving body 21 as an observation window 211, and the size of the opening is set to expose the measuring hole 201 and a portion of the tube nearby. Alternatively, a portion of the tube on the longitudinally elongated single tube can be configured as a transparent tube segment, etc. It can also be used in conjunction with a measuring probe to achieve the effect of image acquisition.

[0082] In some other alternative embodiments, the second receiving body 51 may also be mounted on the frame 10 in a close fit to the side wall of the frame 10.

[0083] like Figure 4 As shown, in some embodiments, the first receiving body 21 of the receiving member 20 is recessed inward near the side wall of the measuring scale 30 to form a longitudinally elongated receiving groove 212. The receiving groove 212 extends parallel to the extending direction of the frame 10, with its bottom closed and its top open, forming a receiving space. The opening of the receiving groove 212 is close to the measuring scale 30 and is blocked (or completely closed) by the side wall of the measuring scale 30, allowing the relevant component 2 or calibration tube to be received within the receiving groove 212.

[0084] By setting the receiving space as a groove-shaped structure with its opening close to the measuring scale 30, the relevant component 2 (or calibration tube) can be closer to the measuring scale than the tubular first receiving body 21 when it is inserted into the receiving space, thereby avoiding measurement errors caused by visual errors due to the gap and improving the accuracy of the measurement.

[0085] In this embodiment, the horizontal cross-section of the first receiving body 21 is rectangular, with one side adjacent to the measuring scale 30. This adjacent side is recessed in a direction away from the measuring scale 30, forming a U-shaped receiving groove 212.

[0086] In some other alternative embodiments, the cross-sectional shape of the first receiving body 21 may also be circular or the like. In this case, "the side wall of the first receiving body 21 near the measuring scale 30" refers to the portion of the wall surface of the first receiving body 21 near the end of the measuring scale 30.

[0087] In some embodiments, the measuring scale 30 has graduations (not shown) on its front side near the receiving member 20 for marking length dimensions. Its accuracy is less than or equal to 0.02 mm, ensuring the system's measurement error is within 0.02 mm, achieving millimeter-level precision measurement.

[0088] In some embodiments, the measuring scale 30 has multiple spaced graduation lines on its side facing away from the frame 10. Each graduation line is at a different distance from the reference position, so that the distance to the reference position can be read through the graduation lines. The projection of the plane of the measuring scale 30 containing the graduation line toward the receiving groove 212 can be located within the receiving groove 212 to reduce errors generated during the reading of the graduation lines.

[0089] like Figure 2 As shown, the measuring scale 30 further includes at least one reference groove 31 formed on the side near the housing 20, with the opening of the reference groove 31 facing the observation window 211. The reference position is located at the top or bottom of the reference groove 31.

[0090] In this embodiment, there are three reference grooves 31, all of which are U-shaped grooves, with their top or bottom walls perpendicular to the contact surfaces of the measuring scale 30 and the receiving member 20. Taking its top wall as the reference position as an example, the setting of the reference groove 31 can reduce measurement errors. By using the groove wall surface as the reference position, confusion between the reference position and the scale line is avoided, ensuring the accuracy of data reading. At the same time, it can avoid errors caused by the size of other types of reference positions due to their own marking structures. Meanwhile, since the opening of the receiving groove 212 of the receiving member 20 faces the measuring scale 30, when the relevant component 2 or calibration tube is received in the receiving groove 212, it can be set adjacent to the measuring scale 30. At this time, the top or bottom wall of the reference groove 31 can indicate the position on the relevant component 2 or calibration tube as closely as possible, further ensuring the accuracy of data reading, that is, the accuracy of measurement.

[0091] In some other alternative embodiments, the reference point can also be set as an easily distinguishable marker line (such as scale lines of different colors and lengths).

[0092] For example Figure 4 As shown, in some embodiments, the front end face of the measuring scale 30 is located behind the front end face of the first receiving body 21 of the receiving member 20, that is, behind the front side wall of the receiving groove 212.

[0093] By setting the front end of the measuring scale 30 behind the front end of the first receiving body 21, the scale lines on the measuring scale 30 can be brought closer to the relevant component 2 or calibration tube in the receiving space during the measurement process. This avoids slight deviations in the angle of image acquisition due to slight differences in the placement angle of the measuring probe, which would lead to visual angle errors in data reading.

[0094] In this embodiment, the front end face of the measuring scale 30 is slightly rearward of the front wall of the receiving groove 212, and is approximately on the same plane as the front side wall of the receiving groove 212. This is to reduce visual angle error.

[0095] In some other alternative embodiments, the front end face of the measuring scale 30 may also be in the same plane as the axis of the receiving groove 212. This ensures that when the relevant component 2 or calibration tube is located within the receiving groove 212, the center of the cross-section of the relevant component 2 or calibration tube lies on the plane containing the front end face of the measuring scale 30. This allows the measuring scale 30 to be brought closer to the relevant component 2 or calibration tube.

[0096] It is important to understand that the "front" and "back" positional relationships mentioned are based on Figure 4 The positional relationship at the angle shown. Figure 4 In the angles shown, the side furthest from the frame 10 is the front end, and the side closest to the frame 10 is the rear end. That is, the side closest to the measuring probe is the front end, and the side furthest from the measuring probe is the rear end.

[0097] like Figure 1 As shown, in some embodiments, the measuring frame 1 further includes at least one probe mounting bracket 40 for holding a measuring probe. The probe mounting bracket 40 is disposed on the frame 10 and located on the side wall where the housing 20 and the measuring scale 30 are located, corresponding to the observation window 211. This allows the measuring probe to be aligned with the observation window 211 and the corresponding reference position when placed on the probe mounting bracket 40. Its detection angle is as follows... Figure 3 As shown, this is to facilitate image acquisition by the measuring probe.

[0098] In this embodiment, there are three probe mounting brackets 40, each corresponding to one of the three observation windows 211.

[0099] Specifically, the probe mounting bracket 40 includes a mounting bracket body 41 and two guide walls 42. The mounting bracket body 41 includes a bottom wall and two side walls, which are vertically erected on opposite sides of the bottom wall, making the mounting bracket body 41 U-shaped. The two guide walls 42 are respectively located at the top of the two side walls and are inclined outwards to guide the insertion of the measuring probe.

[0100] The bottom wall and the rear ends of the two side walls are connected to the frame 10, and an observation window 211 is provided between the two side walls. When the measuring probe is placed in the probe mounting bracket 40, the lens of the measuring probe can be directly facing the observation window 211 between the two side walls, so as to realize the image acquisition of the observation window 211 and the reference position.

[0101] In some embodiments, the probe mounting bracket 40 may also have multiple through holes of different sizes to reduce the overall weight of the measuring bracket 1.

[0102] See also Figure 2 In some embodiments, the measuring probe further includes a housing with a limiting structure at its bottom. Correspondingly, a limiting hole 411 is formed on the bottom wall of the mounting bracket body 41. The limiting structure, positioned within the limiting hole 411, allows the measuring probe to be detachably mounted on the bracket 10. When the measuring probe is placed on the probe mounting bracket 40, the limiting hole 411 ensures that the measuring probe is in the same position on the probe mounting bracket 40 during each measurement. This ensures the repeatability of the mounting position, fixes the distance between the measuring probe and the object being measured, reduces variables, and further ensures measurement accuracy.

[0103] It is important to understand that, to ensure the lifespan of the measuring probe and reduce its underwater placement time, the measuring frame 1 can be installed underwater, and the object to be measured (related component 2 or calibration tube) can be placed in place before the measuring probe is slowly lowered underwater via cables. It is then placed on the probe mounting bracket 40 and fixed in position through the limiting hole 411, thus achieving the installation of the measuring probe.

[0104] This installation method allows for flexible adjustment of the measuring probe, enabling it to be pulled out of the water immediately after measurement, reducing its underwater time and extending its service life. Furthermore, when only one measuring component is used in the nuclear power plant's spent fuel-related component length change measurement system, it can be flexibly moved underwater between the three probe mounting brackets 40. By using a single measuring probe to acquire images on each of the three mounting brackets 40, length measurements of the same object at different locations can be achieved.

[0105] In some other alternative embodiments, the limiting hole 411 may not be provided. Instead, three measuring probes are provided and connected to the three probe mounting brackets 40 respectively by bolts or other connecting parts. The probes are then assembled on the water and placed underwater for image acquisition.

[0106] In some embodiments, the measuring frame 1 further includes a retractable rod and a pool wall hanger (not shown). The retractable rod is detachably mounted on the top of the frame 10 and provides a grip for the operator to slowly lower the frame 10 to the target position underwater by gripping the retractable rod. The pool wall hanger is mounted on the retractable rod and detachably mounted on the edge of the pool. After the frame 10 and other components reach the target position, the pool wall hanger is hung on the edge of the pool to fix the entire measuring frame 1 at the target position.

[0107] In this embodiment, the top of the frame 10 is provided with a connection hole 11, and the bottom end of the extension rod is detachably inserted into the connection hole 11 and detachably connected to the top wall of the frame 10 by bolts or other connecting parts.

[0108] In some embodiments, the top end of the retractable rod may also be provided with a connecting structure so that the lifting mechanism can be connected to it to realize mechanical lifting.

[0109] It should be understood that the connection structure can be a connecting ring, a lug, a hook, etc., and is not limited here.

[0110] like Figure 1 As shown, in some embodiments, the measuring frame 1 further includes at least one abutment bracket 60. This bracket is mounted on the frame 10 and abuts against the pool wall inside the pool when the pool wall hanger is attached to the edge of the pool, providing support and ensuring that the frame 10 and the pool sidewall are parallel and spaced apart.

[0111] Specifically, the abutment bracket 60, the housing 20, the measuring scale 30, and the temporary storage tube 50 are set on the side walls of different frames 10, and their setting positions on the frames 10 are at a certain distance from the pool wall hangers, to ensure the stability of the parallel spacing between the frames 10 and the pool side walls underwater.

[0112] In this embodiment, the side wall of the frame 10 where the temporary storage tube 50 is located, and the side wall of the frame 10 where the housing 20 and the measuring scale 30 are located, are two adjacent side walls. The abutment bracket 60 can be installed on one of the remaining two side walls.

[0113] In this embodiment, the abutment bracket 60 is shaped like a "Z" and its thickness is adapted to the length of the pool wall hanger extending from the edge of the pool, so that the bracket 10 and the side wall of the pool are arranged in parallel intervals.

[0114] In some other alternative embodiments, the abutment bracket 60 may also be arranged in other shapes such as columnar or cylindrical. Its shape is only required to provide abutment and support.

[0115] In this embodiment, the probe mounting bracket 40 can be formed by machining 3mm thick stainless steel sheet metal to improve support stability. The rest of the measuring bracket 1 can be made of hard anodized aerospace aluminum to achieve lightweighting of the equipment while possessing radiation resistance and corrosion resistance.

[0116] In some embodiments, the nuclear power plant spent fuel-related component length variation measurement system further includes a temperature sensor (not shown) mounted on the frame 10 and electrically connected to the controller for measuring underwater temperature.

[0117] In some embodiments, the resolution of the measuring probe is less than or equal to 0.01 mm, so as to control the measurement size error within 0.02 mm.

[0118] In some embodiments, the measuring probe further includes a camera mechanism and an illumination mechanism. Both are housed within a housing. The camera mechanism is used for image acquisition. The illumination mechanism provides illumination in the same direction as the camera mechanism's imaging, and is used to provide lighting during image acquisition.

[0119] Specifically, the camera mechanism includes a camera body (high-definition lens, etc.), an aperture adjustment component 4, and a focus adjustment component. This camera mechanism employs a macro optical system; therefore, the focus adjustment component is used to adjust the focus during measurement to concentrate on the object being measured, resulting in a clearer image. However, because different positions of related components 2 (or calibration tubes) have different reflectivities, the exposure of the imaging system will change. Therefore, the aperture adjustment component 4 is used to adjust the aperture size of the imaging system during measurement to adapt to exposure changes.

[0120] Both the aperture adjustment component 4 and the focus adjustment component are adjusted via motor-driven gear transmission.

[0121] like Figure 5 As shown, the aperture adjustment assembly 4 includes an aperture motor 401, an aperture motor bushing 402, an aperture adjustment gear 403, an aperture adjustment spring 404, and an aperture clamping nut 405.

[0122] The aperture motor 401 is electrically connected to the controller. An aperture motor bushing 402 is fitted onto the output shaft of the aperture motor 401. An aperture adjusting spring 404 and an aperture adjusting gear 403 are both fitted onto the aperture motor bushing 402. An aperture clamping nut 405 is located at the end of the motor bushing and is used to limit the aperture adjusting spring 404 and the aperture adjusting gear 403 to their positions on the aperture motor bushing 402. The aperture adjusting spring 404 is located between the aperture clamping nut 405 and the aperture adjusting gear 403. The aperture adjusting gear 403 is rotatably mounted on the aperture motor bushing 402. When the load on the aperture adjusting gear 403 exceeds a limit, it can slip against the aperture motor bushing 402 due to overload, thus protecting the aperture motor 401.

[0123] The focal length adjustment assembly includes a focal length motor, a focal length motor bushing, a focal length adjustment gear, a focal length adjustment spring, and a focal length clamping nut.

[0124] The focal length motor is electrically connected to the controller. A focal length motor bushing is fitted onto the output shaft of the focal length motor. Both the focal length adjusting spring and the focal length adjusting gear are fitted onto the focal length motor bushing. A focal length clamping nut is located at the end of the motor bushing, used to confine the focal length adjusting spring and the focal length adjusting gear to the focal length motor bushing. The focal length adjusting spring is located between the focal length clamping nut and the focal length adjusting gear. The focal length adjusting gear is rotatably mounted on the focal length motor bushing; when the load on the focal length adjusting gear exceeds a limit, it can slip against the focal length motor bushing due to overload, thus protecting the focal length motor.

[0125] It's important to understand that because adjustment is achieved through gear transmission, a stall can occur when the gears reach the mechanical limit. Prolonged stalling can affect the motor's transmission accuracy and may even damage the motor. By configuring an overload slippage transmission method between the aperture adjustment gear 403 (focal length adjustment gear) and the aperture motor bushing 402 (focal length motor bushing), during aperture adjustment, the aperture adjustment gear 403 (focal length adjustment gear) rotates under the drive of the aperture motor output shaft (focal length motor output shaft) to perform gear transmission. When the gear transmission reaches the mechanical limit, the aperture adjustment gear 403 (focal length adjustment gear) cannot rotate. At this point, the aperture motor 401 (focal length motor) output shaft continues to rotate, causing relative sliding between the aperture adjustment gear 403 (focal length adjustment gear) and the aperture motor bushing 402 (focal length motor bushing), thus preventing stalling and potential motor damage.

[0126] In this embodiment, both the aperture adjustment component 4 and the focal length adjustment component use adjustment gears with a gear module of 0.3 and 140 teeth.

[0127] In some embodiments, the lighting mechanism includes a plurality of lighting lamps arranged around the circumference of the camera subject to ensure uniformity of light.

[0128] It is important to understand that in an underwater environment, water accumulation causes significant attenuation and backscattering of light. In this application, because the measuring probe is close to the object being measured during the measurement operation, the illumination distance is short. Therefore, compared to illumination in an air environment, only an appropriate increase in illumination power is needed to overcome the attenuation effect of water on light.

[0129] In this embodiment, the number of illumination lamps can be four, and the brightness of each lamp can be adjusted independently. Low-power, high-efficiency LED lamps can be selected. LED lamps ensure a small divergence angle (more focused light) in the illumination beam, illuminating the object at a suitable angle with the optical axis of the camera subject, thus minimizing backscattered light entering the lens.

[0130] It is important to understand that this system needs to operate at a depth of approximately 20 meters in an environment with a certain radiation dose. To improve the equipment's adaptability to complex on-site conditions and ease of operation, the measuring probe must possess a certain level of sealing performance. A radiation-resistant sealing ring is selected for static sealing. This ensures a simple, compact structure, minimal space occupation, and easy installation without the need for periodic adjustments. The camera mechanism and lighting mechanism are both sealed within the housing. This housing can also be made of lightweight aerospace-grade aluminum with a hard anodizing treatment to enhance the underwater corrosion resistance and surface hardness of the measuring probe.

[0131] In this embodiment, the imaging resolution of the measuring probe is better than 5 million (2448*2048), the radiation resistance is better than 5*103 rad / h, the measurement field of view is greater than or equal to 17.6mm*13.2mm, the pressure resistance is greater than or equal to 3.0 bar, and the measurement error is less than or equal to 0.02mm.

[0132] It should be understood that the camera mechanism and lighting mechanism can achieve the above effects using existing technologies.

[0133] like Figure 6 As shown, in some embodiments, the controller includes a main control unit, a probe control card, a probe pan-tilt control card, a video image acquisition card, a lighting control card, and a water temperature measurement unit.

[0134] The probe control card, probe pan-tilt control card, video image acquisition card, lighting control card, and water temperature measurement unit are all electrically connected to the main control unit. The image processing unit is used for compressing and storing video images, and the measurement software can also perform two-dimensional geometric dimension measurement. The probe control card is electrically connected to the motors of the aperture adjustment assembly 4 and the focus adjustment assembly, as well as the camera body, for controlling the lens's zoom, focus, aperture, and adjusting parameters such as frame rate, gain, white balance, and exposure time of the camera body. The probe pan-tilt control card is used to control the two-dimensional angle of the camera body. The lighting control card is electrically connected to multiple lighting lamps for individual brightness adjustment to meet different lighting requirements of the target on site. The video image acquisition card is used to acquire video images and perform digital processing for compression and storage; the digitized video images are also easier for the measurement software to process. The water temperature measurement unit is electrically connected to a temperature sensor for real-time acquisition of underwater temperature.

[0135] In some embodiments, the controller can be connected to an external display screen to show the test structure. It may also include a display module, an operating platform, etc., to remotely operate the measurement operation and display the operation results in real time.

[0136] In some embodiments, the controller may also include image capture software that synchronously captures high-resolution images of the video data stream (captures still images) and can capture the target multiple times with different exposure parameters (optical imaging parameters and camera position remain unchanged) to synthesize high-definition high dynamic range (HDR) images.

[0137] In some embodiments, the controller may further include a geometric dimension measurement and comparison function, enabling non-contact measurement of the two-dimensional geometric dimensions of the target through video images, with a feature resolution dimension of less than 0.003 mm. During video inspection, relevant parameters of the target object can also be measured in real time.

[0138] In some embodiments, the controller further includes an uninterruptible power supply (UPS) unit for automatic protection in the event of a power outage and to enable timed self-storage.

[0139] In some embodiments, the controller can be electrically connected to the measurement probe via wireless signal transmission or via cable. When a cable connection is selected, the cable socket can be sealed using existing multi-layer waterproof designs. This considers sealing between the socket and the measurement probe, sealing between the plug and the socket, and sealing between the plug and the cable, thus isolating the internal space of the cable from the internal space of the measurement probe.

[0140] It should be understood that the controller can achieve the above effects using existing technologies.

[0141] like Figure 7 As shown, this application also constructs a method for measuring the length variation of spent fuel-related components in a nuclear power plant, which is applied to any of the aforementioned nuclear power plant spent fuel-related component length variation measurement systems 1. The method includes:

[0142] Step S1: Place the measuring frame 1 and the measuring probe underwater, and place the calibration tube inside the housing 20.

[0143] Step S2: The controller controls the measuring probe to acquire images of the observation window 211 and the reference position 300, and obtains the measurement data of the calibration tube.

[0144] Step S3: Transfer the calibration tube to the temporary storage tube 50 and place the relevant component 2 into the housing 20.

[0145] Step S4: The controller controls the measuring probe to acquire images of the observation window 211 and the reference position 300, and obtains the measurement data of the relevant component 2.

[0146] Step S5: Based on the measurement data of the calibration tube and the measurement data of the relevant component 2, obtain the length change data of the relevant component 2.

[0147] It is important to understand that, prior to step S1, the length variation measurement system 1 for the spent fuel-related components of the nuclear power plant needs to be assembled on land. After assembly, it is slowly lowered underwater by gradually releasing the retraction boom.

[0148] In step S3, the existing single-bar transfer tool can be used to transfer the calibration tube and related components 2.

[0149] like Figure 8 As shown, step S2 includes:

[0150] Step S21: The controller controls the measuring probe to acquire images of the observation window 211 and the reference position 300.

[0151] Step S22: Obtain the distances from the top and bottom of the measuring hole of the calibration tube to the reference position 300.

[0152] Step S23: Repeat steps S21 and S22 at least twice to average the distance from the top of the measurement hole of the calibration tube to the reference position 300, and average the distance from the bottom of the measurement hole of the calibration tube to the reference position 300 to obtain the measurement data of the calibration tube.

[0153] like Figure 9 As shown, step S4 includes:

[0154] Step S41: The controller controls the measuring probe to acquire images of the observation window 211 and the reference position 300.

[0155] Step S42: Obtain the distance from the top and bottom of the measuring hole 201 of the relevant component 2 to the reference position 300.

[0156] Step S43: Repeat steps S41 and S42 at least twice, take the average value of the distance from the top of the measuring hole 201 of the relevant component 2 to the reference position 300, and take the average value of the distance from the bottom of the measuring hole 201 of the relevant component 2 to the reference position 300, to obtain the measurement data of the relevant component 2.

[0157] It is important to understand that the measurement data acquired three times by the calibration tube and related components 2 all correspond to the same measurement port 201. For devices with three observation windows 211 and reference positions 300, the above steps must be performed for each observation window 211 and reference position 300. When the system has three measurement probes, the above steps can be performed simultaneously for all three observation windows 211 and reference positions 300. When the system has only one measurement probe, the above steps must be performed for each observation window 211 and reference position 300 individually.

[0158] The above steps will now be further explained using the measurement of a certain related component 2 as an example:

[0159] like Figure 10 As shown, the three measuring holes 201 on the relevant component 2 are now defined from bottom to top as the first measuring hole 2011, the second measuring hole 2012, and the third measuring hole 2013, respectively. Corresponding to the three measuring holes 201, three reference positions 300 are provided from bottom to top, which are now defined as the first reference position 301, the second reference position 302, and the third reference position 303, respectively.

[0160] For the first measuring hole 2011, in step S42, the distance from its top end to the first reference position 301 is Δy11, and the distance from its bottom end to the first reference position 301 is Δy12. In step S43, the average of the three measurements of Δy11 is taken to obtain the Δy11 after reducing the error. The average of the three measurements of Δy12 is taken to obtain the Δy12 after reducing the error. At the same time, the hole diameter φ1 of the first measuring hole 2011 after reducing the error can be obtained by the difference between Δy12 and Δy11.

[0161] For the second measuring hole 2012, in step S42, the distance from its top end to the second reference position 302 is Δy21, and the distance from its bottom end to the second reference position 302 is Δy22. In step S43, the average of the three measurements of Δy21 is taken to obtain the Δy21 after reducing the error. The average of the three measurements of Δy22 is taken to obtain the Δy22 after reducing the error. At the same time, the diameter φ2 of the second measuring hole 2012 after reducing the error can be obtained by the difference between Δy22 and Δy21.

[0162] For the third measuring hole 2013, in step S42, the distance from its top end to the third reference position 303 is Δy31, and the distance from its bottom end to the third reference position 303 is Δy32. In step S43, the average of the three measurements of Δy31 is taken to obtain the Δy31 after reducing the error. The average of the three measurements of Δy32 is taken to obtain the Δy32 after reducing the error. At the same time, the difference between Δy32 and Δy31 can be used to obtain the diameter φ3 of the second measuring hole 2012 after reducing the error.

[0163] Simultaneously, by using the distance values ​​between two adjacent reference positions 300, and in conjunction with the aforementioned data, we can obtain the following data: distance L4 from the top of the first measuring hole 2011 to the bottom of the second measuring hole 2012; distance L2 from the top of the first measuring hole 2011 to the top of the second measuring hole 2012; distance L3 from the top of the second measuring hole 2012 to the bottom of the third measuring hole 2013; and distance L1 from the top of the second measuring hole 2012 to the top of the third measuring hole 2013 (there are many similar data, which can be obtained through addition and subtraction of known data, and will not be listed here). These data collectively constitute the measurement data of the relevant component 2.

[0164] Because the length of component 2 increases during combustion, the position of the measuring hole 201 at the observation window 211 will shift upwards compared to the calibration tube when component 2 is placed inside the housing 20. Therefore, when a reference groove 31 is provided on the measuring scale 30, the top side wall of the reference groove 31 can be used as the reference position 300. This avoids errors in data acquisition caused by the measuring hole 201 being far from the reference position when measuring component 2 with a higher degree of combustion.

[0165] For example Figure 7 As shown, in some embodiments, step S0 is also included: obtaining the factory data of the calibration tube.

[0166] Step S6: Obtain the scaling factor based on the measurement data of the calibration tube and the factory data. Obtain the actual data of the relevant component 2 based on the measurement data of the relevant component 2 and the scaling factor.

[0167] It is important to understand that underwater image acquisition is subject to environmental errors due to environmental factors, and the factory data for this calibration tube is based on measurements taken in a surface environment. Therefore, by obtaining a scaling factor, environmental errors in underwater measurements can be eliminated, thereby improving measurement accuracy.

[0168] Specifically, this scaling factor can be obtained using Formula 1:

[0169]

[0170] Where k is a scaling factor, and its unit is μm;

[0171] k' is a constant;

[0172] b represents the measurement data from the calibration tube;

[0173] 'a' represents the factory data for the calibration tube.

[0174] It is important to understand that step S6 can be performed at any time after step S2. That is, it can be performed after step S3 or step S4.

[0175] In some embodiments, step S4 further includes:

[0176] Step S40: Allow the relevant component 2 to remain stationary within the housing 20 for a preset time.

[0177] Step S41 includes: after the preset time is reached, the controller controls the measuring probe to acquire images of the observation window 211 and the reference position 300.

[0178] By allowing the material to stand for a certain period of time, the linear expansion of the relevant component 2 can be stabilized, further avoiding measurement errors.

[0179] In this embodiment, the preset time is ten minutes.

[0180] It is understood that the above embodiments only illustrate some implementation methods 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 for those skilled in the art, the above technical features can be freely combined, and several modifications and improvements can be made without departing from the concept of the present invention, 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 system for measuring the length variation of spent fuel-related components in a nuclear power plant, used to measure the length variation of the related components (2) and the calibration tube respectively, to obtain length variation data of the related components (2), characterized in that, The nuclear power plant spent fuel related component length change measurement system includes a measuring frame (1), which includes: The frame (10) is arranged longitudinally; The receiving component (20) is mounted on the frame (10) and extends in a direction parallel to the frame (10). The receiving component has a receiving space for receiving the related component (2) or the calibration tube, and the receiving component (20) is provided with at least one observation window (211) for exposing a measuring hole (201) of part of the related component (2) or the calibration tube. A measuring scale (30) is mounted on the frame (10) and extends in a direction parallel to the frame (10) and is adjacent to the housing (20). The measuring scale (30) has at least one reference position (300) corresponding to the observation window (211). A temporary storage tube (50) is used to temporarily store the relevant component (2) or the calibration tube. The temporary storage tube (50) is installed on the frame (10) and extends in a direction parallel to the frame (10). A measuring probe is used to acquire images of the observation window (211) and the reference position (300); and The controller is electrically connected to the measuring probe; The receiving space is a longitudinal receiving groove (212) formed by the inward indentation of the side wall of the receiving component (20) near the measuring scale (30), and the extending direction of the receiving groove (212) is parallel to the extending direction of the frame (10). The measuring scale (30) has at least one reference groove (31) formed on the side near the housing (20), the opening of the reference groove (31) facing the observation window (211), and the reference position (300) located at the top or bottom of the reference groove (31).

2. The nuclear power plant spent fuel-related component length variation measurement system according to claim 1, characterized in that, The receiving component (20) includes a receiving body and a guide. The guide is in the shape of a trumpet, and the constricted end of the guide is connected to the top of the receiving body. The receiving body is longitudinally elongated, hollow inside to define the receiving space, and connected to the guide.

3. The nuclear power plant spent fuel-related component length change measurement system according to claim 1, characterized in that, The number of observation windows (211) and reference positions (300) are both three, and the three observation windows (211) correspond to the three measuring holes (201) on the related component (2).

4. The nuclear power plant spent fuel-related component length change measurement system according to claim 1, characterized in that, The opening of the receiving slot (212) is located close to the measuring scale (30). The measuring scale (30) has multiple spaced graduation lines on its side away from the frame (10), and each graduation line is at a different distance from the reference position.

5. The nuclear power plant spent fuel-related component length variation measurement system according to any one of claims 1 to 3, characterized in that, The measuring frame (1) also includes at least one probe mounting bracket (40) for placing the measuring probe. The probe mounting bracket (40) is disposed on the frame (10) and corresponds to the observation window (211).

6. The nuclear power plant spent fuel-related component length change measurement system according to claim 5, characterized in that, The measuring probe includes a housing, and a limiting member is provided at the bottom of the housing. A limiting hole (411) corresponding to the limiting member is formed on the probe mounting bracket (40), and the limiting member is limited within the limiting hole (411).

7. The nuclear power plant spent fuel-related component length variation measurement system according to any one of claims 1 to 3, characterized in that, The front end face of the measuring scale (30) is located on the rear side of the front sidewall of the receiving groove (212).

8. A method for measuring the length variation of spent fuel-related components in a nuclear power plant, applied to the length variation measurement system for spent fuel-related components in a nuclear power plant as described in any one of claims 1 to 7, characterized in that, The method for measuring the length variation of spent fuel-related components in nuclear power plants includes: Step S1: Place the measuring frame (1) and the measuring probe underwater, and place the calibration tube inside the housing (20); Step S2: The controller controls the measuring probe to acquire images of the observation window (211) and the reference position (300) to obtain the measurement data of the calibration tube; Step S3: Transfer the calibration tube into the temporary storage tube (50) and place the relevant component (2) into the housing (20); Step S4: The controller controls the measuring probe to acquire images of the observation window (211) and the reference position (300) to obtain the measurement data of the relevant component (2); Step S5: Obtain the length change data of the relevant component (2) based on the measurement data of the calibration tube and the measurement data of the relevant component.

9. The method for measuring the length variation of spent fuel-related components in a nuclear power plant according to claim 8, characterized in that, Step S2 includes: Step S21: The controller controls the measuring probe to acquire images of the observation window (211) and the reference position (300); Step S22: Obtain the distance from the top of the measuring hole of the calibration tube to the reference position and the distance from the bottom of the measuring hole to the reference position (300); Step S23: Repeat steps S21 and S22 at least twice, take the average value of the distance from the top of the measuring hole of the calibration tube to the reference position (300), and take the average value of the distance from the bottom of the measuring hole of the calibration tube to the reference position (300) to obtain the measurement data of the calibration tube. Step S4 includes: Step S41: The controller controls the measuring probe to acquire images of the observation window (211) and the reference position (300); Step S42: Obtain the distances from the top and bottom of the measuring hole (201) of the relevant component (2) to the reference position (300); Step S43: Repeat steps S41 and S42 at least twice, take the average value of the distance from the top of the measuring hole (201) of the related component (2) to the reference position (300), and take the average value of the distance from the bottom of the measuring hole (201) of the related component (2) to the reference position (300) to obtain the measurement data of the related component (2).

10. The method for measuring the length variation of spent fuel-related components in a nuclear power plant according to claim 8, characterized in that, It also includes step S0: obtaining the factory data of the calibration tube; Step S6: Obtain the scaling factor based on the measurement data of the calibration tube and the factory data; obtain the actual data of the related component (2) based on the measurement data of the related component (2) and the scaling factor; The scaling factor is calculated using Formula 1: Formula 1 Where k is the scaling factor; k' is a constant; b represents the measurement data from the calibration tube; 'a' represents the factory data for the calibration tube.

Images