A nuclear fuel rod weld ultra-high frequency eddy current array scan detection sensor and method

Abstract

The present application relates to the technical field of nuclear fuel rod detection, and particularly relates to a nuclear fuel rod end plug weld joint ultra-high frequency eddy current variable array scanning detection sensor and method. A ring-shaped framework is sleeved on the outer periphery of the nuclear fuel rod. A detection sensor area is arranged on the inner side wall of the ring-shaped framework. The ring-shaped framework is rotated to detect the ring weld joint defects. A plurality of coil assemblies with different angles are arranged on the detection sensor area. The computer controls the rapid switching of the coil excitation or receiving function, the setting of the excitation and receiving times, the setting of the excitation sequence and frequency and intensity, and further uses the ultra-high frequency excitation to improve the detection sensitivity. The same position is detected multiple times at multiple frequencies and multiple angles in the variable array mode, a large amount of detection data is quickly obtained, the information of the small defects of the nuclear fuel rod weld joint is obtained through special data processing and image processing, the small defects and discontinuity of the weld joint are found, the reliability of the defect detection result is improved, and the accurate detection purpose is achieved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of nuclear fuel rod detection, and particularly relates to a nuclear fuel rod weld joint ultra-high frequency eddy current variable array scanning detection sensor and method. BACKGROUND

[0002] Nuclear power generation is one of the clean and controllable energy sources discovered by human beings, and does not cause pollution to the environment during nuclear power operation, and is a long-term exploitable energy source. The nuclear fuel rod is an essential key element in the core reactor, and the nuclear fuel rod occurs nuclear fission in the reactor to convert energy into electric energy. The quality of the nuclear fuel rod directly affects the economy and safety of the nuclear reactor, and therefore needs to be strictly controlled during the preparation of the nuclear fuel rod. Since the end cap and the tube body need to be welded during the manufacturing process, it is the first barrier to prevent leakage, and therefore the end plug weld joint of the nuclear fuel rod needs to be strictly controlled to prevent leakage.

[0003] The existing nuclear fuel rods are of various types, and the characteristics of the weld joints are different. The conventional modern non-destructive testing methods such as ultrasonic, ray or conventional eddy current cannot be well applied to the detection of various nuclear fuel rod end plug weld joints, especially for a small diameter tube rod, the end plug has a clamping groove matched with the tube port, the end plug is embedded in the tube port, and is welded by resistance welding. The depth of the weld joint is about 0.2mm, and the weld joint width is relatively narrow (usually about 0.3mm), and for the small defects or discontinuities (such as a 0.1mm deep crack) existing on the surface of the weld joint, so far, no conventional NDT can meet the detection requirements. The present application is improved on the basis of the prior art, and researches a nuclear fuel rod weld joint ultra-high frequency eddy current variable array scanning detection method, and strives to solve the above problems. SUMMARY

[0004] In order to solve the above problems, improve the detection sensitivity of the small defects, and find the abnormal parts of the weld joint, the present application provides a nuclear fuel rod weld joint ultra-high frequency eddy current variable array scanning detection sensor and method, and the present application is implemented as follows:

[0005] The utility model provides a kind of nuclear fuel rod weld seam ultra-high frequency eddy current variable array scanning detection sensor for the detection of nuclear fuel rod tube and end plug interface weld seam defects, including sequentially connected handle, probe rod and annular framework, detection sensing area is provided on the inner side wall of the annular framework, the detection sensing area includes several groups of same structure coil assembly, the coil assembly is equidistantly arranged along the circumference of annular framework, and the embedding angle of multiple coil assemblies is set to multiple different angles, and signal interference shielding element is provided between adjacent coil assemblies, wherein each group of coil assembly includes a plurality of arrayed detection coils, the detection coil is switched by computer control Coil excitation or receiving function, the setting of excitation and receiving times and the setting of excitation order and frequency, intensity.

[0006] As a further improvement, the embedding angle of the coil assembly is 45°, 90°, 135° in turn.

[0007] As a further improvement, the direction extending along the circumference of the annular framework is defined as the scanning length of the coil assembly, and the direction extending along the axis of the coil framework is defined as the scanning width of the coil assembly, wherein the scanning width of the coil assembly can cover the width of the girth weld.

[0008] As a further improvement, the annular framework extends upward to form an identification pointer corresponding to the position of the detection sensing area, and a scale identifier is rotationally arranged on the outer periphery of the annular framework, and the identification pointer and the scale identifier cooperate to determine the rotation angle of the detection sensing area.

[0009] The utility model also discloses a kind of nuclear fuel rod weld seam ultra-high frequency eddy current variable array scanning detection method for the detection of nuclear fuel rod tube and end plug interface weld seam defects, annular framework is set on the outer periphery of nuclear fuel rod, detection sensing area is provided on the inner side wall of the annular framework, and nuclear fuel rod girth weld defect is detected by rotating annular framework, any one of the above-mentioned detection sensors is used, and the specific steps are as follows:

[0010] a, a large number of detection signal samples are acquired for the weld seam at the same position: during detection, a group of coil assemblies are controlled by computer to detect the weld seam at the same position multiple times, multiple transmission and single reception detection mode is used each time, array element switching of excitation and receiving unit is sequentially performed between different detections, and multiple variable array detection is carried out using different ultra-high frequency excitation frequencies;Further, when multiple frequency and multiple variable array detection of a group of coil assemblies is completed, detection sensing area is rotated to adjacent coil assembly for detection at different angles;Using the repeatability of nuclear fuel rod natural defect signals, multiple angle, multiple frequency and multiple variable array signals are collected for the weld seam at the same position to obtain a large number of detection signal samples;

[0011] b. Acquisition of complete circumferential weld detection signals: After a group of coil assemblies completes the detection work of a fixed point, the detection sensing area is rotated to the next fixed point to perform the same detection work until each group of coil assemblies has completed the detection of each fixed point;

[0012] c. Data processing: The acquired signals are grouped and sorted, and after analog-to-digital conversion, image processing is performed on the large data sample to obtain different frequency response curves of the weld at the same location.

[0013] d. Analysis of test results: The test results are located and quantitatively analyzed. The signal curve after image processing is compared with the signal curve of artificial defects in the sample, and it is determined whether there are abnormal minor defects or discontinuities in the weld at the fixed point.

[0014] As a further improvement, in step b, adjacent coil assemblies operate synchronously.

[0015] As a further improvement, step d also includes qualitative defect analysis. The types of abnormal minor defects include air bubbles in the weld, incomplete weld penetration, weld depressions, and weld cracks. The artificial defect signal curves of the test blocks corresponding to different abnormal defect types are different. The signal curves are compared and defects are evaluated by computer.

[0016] Compared with existing technologies, this application can achieve the following technical effects:

[0017] I. The present invention employs an eddy current variable array scanning detection method, which, compared with traditional ultrasonic or X-ray detection methods, offers greater flexibility in the detection sensor structure, eliminates the need for coupling agents or corresponding transceiver structures, and enables better in-situ detection.

[0018] Second, the detection sensor of this invention adopts an ultra-high frequency variable array coil assembly. Furthermore, by grouping the coil assemblies and equidistantly arranging them along the circumference of a ring-shaped frame, and setting different embedding angles for each group of coil assemblies, a multi-angle comprehensive detection is achieved. Each group of coil assemblies is configured with a variable array coil structure. A computer is used to switch the excitation and reception of the coils according to different detection modes, set the number of excitations and receptions, and configure the excitation sequence, frequency, and intensity. The structure is simple and can quickly acquire various detection data under different modes, expanding the detection data sample. The ultra-high frequency excitation signal setting has a good detection effect and high detection sensitivity for small abnormal defects on the weld surface.

[0019] Third, the detection sensor of the application sets signal interference shielding elements between adjacent coil assemblies, and adjacent coil assemblies can detect adjacent to-be-detected fixed point positions at the same time during detection, improving detection efficiency. Meanwhile, when a fixed point position is detected under a group of coil assemblies, the next group of coil assemblies with different embedded angles are rotated to detect the fixed point position, and the previous group of coil assemblies can detect the next fixed point position. Only the annular framework with the detection sensor needs to be rotated in one direction, improving the continuity of detection operation.

[0020] Fourth, the detection method of the application can form various detection signal acquisition modes through the variable array coil assembly arrangement characteristics. A group of coil assemblies can perform multi-frequency and multi-time variable array detection on the same position of the weld, different groups of coil assemblies are used to detect the same position of the weld by rotating the detection sensing area, and a large number of detection signal samples of the weld at the same position under multi-angle, multi-frequency, and multi-time variable array detection are further obtained. The repeatability of the natural defects of the nuclear fuel rod ring weld and the structural characteristics of the detection station are used to obtain a large amount of data at the same fixed point, improve the signal-to-noise ratio, and realize accurate evaluation based on a large amount of detection data.

[0021] Fifth, the data processing method of the application collects data in groups and levels, processes the collected large amount of data, and compares the formed frequency response signal curve of the same fixed point with the artificial defect signal curve of the simulated sample to evaluate the defects, which is beneficial to find abnormal parts and types of the weld. BRIEF DESCRIPTION OF DRAWINGS

[0022] In order to more clearly illustrate the technical solutions of the application examples or the prior art or the descriptions in the prior art, it is obvious that other drawings can be obtained by those skilled in the art without creative labor on the basis of these drawings.

[0023] Figure 1 It is an appearance diagram of a nuclear fuel rod.

[0024] Figure 2 It is a structural diagram of the nuclear fuel rod along the main view direction.

[0025] Figure 3 It is Figure 2 It is a sectional view along the A-A line.

[0026] Figure 4 It is Figure 3 It is an enlarged schematic view of the B area.

[0027] Figure 5 It is a schematic diagram of the use of the detection sensor in the embodiment.

[0028] Figure 6 The structure diagram of the detection sensor in the embodiment.

[0029] Figure 7 The structure diagram of the detection sensor in the embodiment. Figure 6 The enlarged diagram of the C area in the embodiment.

[0030] Figure 8 The layout and array switching diagram of a group of coil assemblies in the embodiment.

[0031] Figure 9 The brief flow chart of the detection method of the embodiment.

[0032] In the figure:

[0033] 10-nuclear fuel rod, 11-tube, 12-end plug, 13-circumferential weld;

[0034] 20-detection sensor, 21-handle, 22-probe rod, 23-circular skeleton, 231-identification pointer, 24-scale identifier, 25-detection area, 251-detection coil (a1, a2, a3, a4, a5, a6, a7, a8). DETAILED DESCRIPTION

[0035] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are some of the embodiments of the present application, but not all the embodiments of the present application. Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the claimed present application, but only represents selected embodiments of the present application.

[0036] In the description of the present application, the terms “first” and “second” are only used for description purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined with “first” and “second” can explicitly or implicitly include one or more of the features.

[0037] Nuclear power generation is an important way to realize low-carbon power generation, and is one of the clean, reliable and long-term developed energy sources discovered so far. As an important component in the nuclear reactor, the quality of the nuclear fuel rod is of great importance, especially the tube and the upper and lower end plugs of the nuclear fuel rod are usually connected and sealed by welding, and defects are prone to occur at the welding position. Therefore, effective detection of the welding seam is required.

[0038] The traditional detection of the end plug weld of the nuclear fuel rod mainly adopts the ray detection method, which is gradually replaced by other detection methods such as ultrasonic and eddy current, because of its long detection cycle, high cost and radiation damage in the operation process. With the emergence of nuclear safety problems, the detection of each component of the nuclear power structure has higher requirements. The ultrasonic detection has some limitations in the new detection requirements due to the need for coupling agent. The conventional eddy current detection method also gradually cannot meet the detection requirements. Based on the existing technology, the present application improves the detection sensitivity of the micro-defects, improves the detection rate of the abnormal defects of the weld, and enhances the reliability of the fuel rod.

[0039] The nuclear fuel rod weld ultra-high frequency eddy current variable array scanning detection sensor designed by the present application is used for detecting the weld defects of the nuclear fuel rod tube and the end plug, wherein the structure of the nuclear fuel rod is shown in the attached Figures 2-4 The detected nuclear fuel rod is a small diameter tube rod, the upper end of the end plug has a conical arc surface, the lower end has a clamping groove matched with the pipe opening of the tube, the clamping groove is embedded in the pipe opening, the joint between the pipe opening and the end plug is welded by electronic welding, the weld is located on the inner side of the tube wall and the end plug clamping groove wall, the depth of the weld is about 0.2mm, and the weld width is relatively narrow (usually about 0.3mm), the overall structure is fine, and the nondestructive detection of the small abnormal defects on the weld surface is a great challenge.

[0040] The attached Figures 5-6 The detection sensor comprises a handle, a probe rod and a ring-shaped skeleton connected in sequence, the probe rod is a rigid probe rod, the probe rod is connected to the position close to the detection sensor area on the outer periphery of the ring-shaped skeleton, the inner wall of the probe rod is hollow and used for accommodating the detection line, the handle is integrated with the probe rod and is provided with an integrated cable plug interface, and the detection signal is transmitted to the computer through the cable plug interface. The inner side wall of the ring-shaped skeleton is provided with a detection sensor area, the detection sensor area comprises a plurality of groups of coil assemblies with the same structure, the coil assemblies are equidistantly arranged along the circumference of the ring-shaped skeleton, the embedding angles of the plurality of groups of coil assemblies are set to be a plurality of different angles, and the signal interference shielding elements are arranged between adjacent coil assemblies, wherein each group of coil assemblies comprises a plurality of detection coils arranged in an array, and the detection coils are quickly switched by the computer control to realize the functions of coil excitation or reception, set the number of excitation and reception, and set the excitation sequence, frequency and intensity.

[0041] The detection sensor adopted by the application has simple structure and is convenient to operate, a plurality of coil assemblies are arranged in the detection sensing area, each coil assembly works independently, the detection sensing area is turned to the corresponding to-be-detected area, the switching of the coil function is controlled by the computer, a plurality of detection data of a fixed point in different modes can be quickly obtained, and the detection data samples are expanded. The excitation of the detection coil adopts an ultrahigh-frequency excitation signal, the setting of the ultrahigh-frequency excitation signal has good detection effect and high detection sensitivity on the small abnormal defects on the weld surface. A plurality of coil assemblies are arranged at multiple angles and are used for obtaining detection data of multiple angles at the same fixed point position, and the weld at the same fixed point position can be more accurately analyzed and judged based on the multiple-angle detection data. The signal interference shielding elements are arranged between the adjacent coil assemblies, the adjacent coil assemblies can work synchronously without interference during detection, and the detection efficiency is improved.

[0042] As a further improvement, the direction extending along the circumference of the annular skeleton is defined as the scan length of the coil assembly, and the direction extending along the axial direction of the coil skeleton is defined as the scan width of the coil assembly, wherein the scan width of the coil assembly can cover the width of the girth weld. The scan width of the coil assembly fully covers the width of the girth weld to prevent the edge weld from being missed. In the embodiment, the width of the girth weld is about 0.3mm, and the scan width of the coil assembly used is greater than or equal to 0.3mm.

[0043] In the embodiment, the weld between the tube and the end plug of the nuclear fuel rod is detected manually, in order to facilitate the determination of the rotation angle of the detection sensing area, as a further improvement, the annular skeleton is extended upward to form an identification pointer corresponding to the position of the detection sensing area, and a scale identifier is arranged on the outer periphery of the annular skeleton, and the identification pointer and the scale identifier cooperate to determine the rotation angle of the detection sensing area.

[0044] The application also discloses a nuclear fuel rod weld ultrahigh-frequency eddy current variable array scanning detection method for detecting the defects of the weld between the tube and the end plug of the nuclear fuel rod, wherein an annular skeleton is arranged on the outer periphery of the nuclear fuel rod, a detection sensing area is arranged on the inner side wall of the annular skeleton, the annular skeleton is rotated to make the detection sensing area correspond to the to-be-detected area to detect the defects of the girth weld of the nuclear fuel rod, and any one of the detection sensors described above is adopted.

[0045] a. Obtaining a large number of detection signal samples of the weld at the same position: during detection, a set of coil assemblies is controlled by a computer to detect the weld at the same position multiple times, and each detection adopts a detection mode of multiple transmission and one reception, that is, in the set of coil assemblies, one receiving coil corresponds to multiple excitation coils; the array element switching of the excitation and receiving units is sequentially performed between different detections, and different detections adopt different ultrahigh frequency excitation frequencies to perform multi-frequency and multi-time array switching detection; further, when the multi-frequency and multi-time array switching detection of the set of coil assemblies is completed, the detection sensing area is rotated to an adjacent coil assembly to perform detection at different angles; the repeatability of the nuclear fuel rod natural defect signal is used to perform multi-angle, multi-frequency, and multi-time array switching signal collection of the weld at the same position to obtain a large number of detection signal samples;

[0046] b. Obtaining detection signals of the complete girth weld: after the detection of one set of coil assemblies at one fixed point is completed, the detection sensing area is rotated to the next fixed point to perform the same detection work, until each set of coil assemblies completes the detection at each fixed point; the adjacent coil assemblies work synchronously.

[0047] c. Data processing: the obtained signals are grouped and classified, and are subjected to analog-to-digital conversion; on the basis of large data samples, the data is subjected to image processing to obtain different frequency response curves of the weld at the same position;

[0048] d. Analysis of the detection results: the detection results are subjected to positioning and quantitative analysis, the signal curves after image processing are compared with the signal curves of the artificial defects of the sample, and it is determined whether the weld at the fixed position has abnormal micro defects or discontinuity.

[0049] In the embodiment, three sets of coil assemblies are arranged, and the detection coils in each set of coil assemblies are arranged in a "pin-shaped" staggered manner to form a row-column array, and preferably, eight detection coils are arranged to form a three-column arrangement, as shown in FIG. 2. Figure 8 The detection coils are sequentially numbered (a1, a2, a3, …, a8), and during detection, a detection mode of multiple transmission and one reception is adopted, the number of receiving coils in one coil assembly can be set to one or two, and the number of excitation coils is correspondingly set. In the embodiment, the number of receiving coils in the coil assembly is set to one, and the number of excitation coils is set to seven, when the receiving coil R = a1, the excitation coils T = a2, a3, a4, a5, a6, a7, a8. Similarly, array switching detection is adopted, and the array element switching of the excitation and receiving units is controlled by a computer, that is, the receiving coil R = {a1, a2, a3, …, a8}, and the corresponding excitation coils T = {(a2, a3, a4, a5, a6, a7, a8), (a1, a3, a4, a5, a6, a7, a8), (a1, a2, a4, a5, a6, a7, a8) … (a1, a2, a3, a4, a5, a6, a7)}.

[0050] In the detection, the array element switching of the excitation and receiving unit is sequentially performed between different detections, and the detection is performed in multiple frequencies and multiple times by using different ultrahigh frequency excitation frequencies. In the embodiment, in order to further improve the detection sensitivity of the micro defect, the coil is excited by using an ultrahigh frequency, and the excitation frequency is preferably set to be between 5 MHz and 15 MHz. Further, the embedding angles of the coil assembly are 45°, 90° and 135° in sequence. When the detection work of a group of coil assemblies on a fixed point position is completed, the detection sensor area is rotated to switch the coil assembly with different embedding angles to detect the fixed point position again. Since the embedding angles of the coil assemblies are different, the lifting of the surface to be detected will also be different, and the differences between the detection signals obtained will exist. Through a large number of data samples, the signal characteristics are fitted and analyzed by a computer, and whether the weld has a micro defect or discontinuity is evaluated.

[0051] As a further improvement, the step d further includes defect qualitative analysis, the abnormal micro defect types include bubbles remaining in the weld, incomplete penetration of the weld, depression in the weld, weld cracks and the like; the artificial defect signal curves of the test blocks corresponding to different abnormal defect types are different, and the signal curves are compared and the defects are evaluated by a computer.

[0052] The above only describes the preferred embodiments of the present application and is not used to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement and the like made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A high-frequency eddy current variable array scanning sensor for inspecting weld seams of nuclear fuel rods, used for detecting defects in weld seams connecting nuclear fuel rod tubes and end plugs, comprising a handle, a probe, and an annular frame connected in sequence, characterized in that... The inner wall of the ring-shaped skeleton is provided with a detection sensing area, the detection sensing area comprises a plurality of groups of coil assemblies with the same structure, the coil assemblies are equidistantly arranged along the circumference of the ring-shaped skeleton, the embedding angles of the plurality of groups of coil assemblies are set to be a plurality of different angles, and a signal interference shielding element is arranged between adjacent coil assemblies, wherein each group of coil assemblies comprises a plurality of arrayed detection coils, and the detection coils are controlled by a computer to quickly switch the coil excitation or receiving function, set the excitation and receiving times, and set the excitation sequence and frequency and intensity.

2. A nuclear fuel rod weld ultra-high frequency eddy current array scan test sensor according to claim 1, characterized in that, The embedding angles of the coil assemblies are 45°, 90° and 135° in sequence.

3. A nuclear fuel rod weld ultra-high frequency eddy current array scan test sensor according to claim 2, wherein, The direction extending along the circumference of the ring-shaped skeleton is defined as the scanning length of the coil assembly, and the direction extending along the axis of the ring-shaped skeleton is defined as the scanning width of the coil assembly, wherein the scanning width of the coil assembly can cover the width of the ring weld.

4. A nuclear fuel rod weld ultra-high frequency eddy current array scan test sensor according to claim 3, wherein, The ring-shaped skeleton extends upward to form an identification pointer at the position corresponding to the detection sensing area, and a scale identifier is arranged on the outer periphery of the ring-shaped skeleton, and the identification pointer and the scale identifier cooperate to determine the rotation angle of the detection sensing area.

5. A nuclear fuel rod weld UHF eddy current array scanning detection method for detecting the defects of the joint weld between the nuclear fuel rod tube and the end plug, a ring-shaped skeleton is arranged on the outer periphery of the nuclear fuel rod, a detection sensing area is arranged on the inner side wall of the ring-shaped skeleton, and the ring-shaped skeleton is rotated to detect the defects of the nuclear fuel rod girth weld, characterized in that, The specific steps of using the detection sensor of any one of claims 1 to 4 are as follows: a. A large number of detection signal samples are obtained for the weld at the same position: during detection, a group of coil assemblies are controlled by a computer to detect the weld at the same position multiple times, each detection adopts a multi-transmission and single-reception detection mode, the array element switching of the excitation and receiving units is sequentially performed between different detections, and different ultrahigh frequency excitation frequencies are adopted for multiple array detection; further, when the multiple frequency and multiple array detection of a group of coil assemblies is completed, the detection sensing area is rotated to the adjacent coil assembly for detection at different angles; the repeatability of the nuclear fuel rod natural defect signal is used to perform signal collection at multiple angles, multiple frequencies and multiple times for the weld at the same position to obtain a large number of detection signal samples; b. Detection signal of complete ring weld is obtained: after a group of coil assemblies complete the detection work at a fixed point, the detection sensing area is rotated to the next fixed point for the same detection work until each group of coil assemblies completes the detection at each fixed point; c. Data processing: the obtained signals are grouped and classified, and after analog-digital conversion, the data is processed on the basis of large data samples to obtain different frequency response curves of the weld at the same position; d. Analysis of detection results: the detection results are positioned and quantitatively analyzed, the signal curves after image processing are compared with the signal curves of the artificial defects of the sample, and it is determined whether the weld at the fixed position has abnormal micro-defects or discontinuity.

6. A method of EHF eddy current array scanning of a weld seam of a nuclear fuel rod according to claim 5, characterized in that In step b, the adjacent coil assemblies work synchronously.

7. A method of EHF eddy current array scanning of a weld seam of a nuclear fuel rod as defined in claim 6, characterized in that In step d, the qualitative analysis of defects is also included, the types of abnormal micro-defects include bubbles remaining in the weld, incomplete penetration of the weld, depression in the weld and cracks in the weld; the artificial defect signal curves of the test blocks corresponding to different types of abnormal defects are different, and the signal curves are compared and the defects are evaluated by a computer.

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