A high-precision detection method for nuclear fuel rod end plug weld defects

Abstract

The application discloses a kind of high-precision detection methods of nuclear fuel rod end plug weld defects, including when nuclear fuel rod is placed in end plug detection station, by chuck device from the end of the rod body near clamping nuclear fuel rod;Chuck device controls nuclear fuel rod rotation, while controlling line-scan spectroscopy camera to move to the rod body above nuclear fuel rod end plug near nuclear fuel rod and carry out pre-scanning;Control line-scan spectroscopy camera moves to the end plug above nuclear fuel rod along nuclear fuel rod axial direction and carries out scanning detection to nuclear fuel rod end plug portion;System carries out data comparison processing to the data obtained by pre-scanning and the data obtained by scanning detection, and judges the defect condition of nuclear fuel rod end plug weld according to the data obtained by scanning detection.The application effectively eliminates the jumping error generated in the process of nuclear fuel rod rotation detection without changing the cost of equipment by adjusting the process of design detection data and the depth processing of detection data, realizes the effect of improving detection precision.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of nuclear fuel rod surface defect detection, in particular to a high-precision detection method for nuclear fuel rod end plug weld defects. BACKGROUND

[0002] The defect detection of the end plug weld part of the nuclear fuel rod mainly involves the detection of the oxidized color area at the end plug weld, the detection of the end plug weld width, the detection of mechanical damage at the end plug weld, and the detection of damage depth, etc., among which the width detection and mechanical damage detection generally use a line-scan spectral camera to realize damage image recognition, and the required detection precision is generally at the level of 10 - 2 mm. The detection process generally clamps the rod body of the nuclear fuel rod by a chuck, then rotates, and then scans the end plug part by linear movement of the chuck or the line-scan spectral camera, and identifies the defect condition from the scanned image data. The main way to improve the detection precision of the traditional detection method is to upgrade the structure of the chuck part or upgrade the line-scan spectral camera to improve the precision of the chuck and the scanning image, so as to improve the final detection precision. The main disadvantage is that even if the chuck device is of high precision, the performance of the chuck device part will decrease due to structural wear and other factors after a long time of use, and the detection precision will decrease quickly, and the user has to replace the new high-precision chuck device to ensure the detection precision, so that the equipment use cost and maintenance cost are very high.

[0003] On the other hand, since the chuck device can only clamp the rod body, it is single-end clamping for the end plug part to be detected, and the nuclear fuel rod needs to be rotated during detection, which will inevitably cause a certain jump of the end part of the nuclear fuel rod, thereby producing jump error in the detection data, which will seriously affect the final detection precision, so higher precision chuck devices and line-scan spectral cameras are usually configured according to the target detection precision requirement to minimize the interference of the jump error, which undoubtedly greatly increases the equipment cost. Moreover, even so, the jump error cannot be completely overcome.

[0004] In view of this, the present application proposes a design scheme for improving the defect detection precision of the end plug weld part of the nuclear fuel rod without significantly increasing the equipment cost from the perspective of detection data processing. SUMMARY

[0005] In view of the problems existing in the prior art, the present application provides a high-precision detection method for nuclear fuel rod end plug weld defects, which increases the rod body scanning detection to obtain the jump error data caused by rotation and eliminates the jump error in the normal scanning detection, thereby improving the detection precision without increasing the equipment cost.

[0006] In order to achieve the above object, the technical scheme adopted by the present application is as follows:

[0007] A high-precision detection method for end plug weld defects of a nuclear fuel rod, comprising the following steps:

[0008] S1, when the nuclear fuel rod is placed on the end plug detection station, the clamping head device clamps the nuclear fuel rod from the rod body close to the end;

[0009] S2, pre-scanning: the clamping head device controls the rotation of the nuclear fuel rod, and controls the line-scan spectral camera to move above the rod body near the end plug of the nuclear fuel rod to pre-scan the nuclear fuel rod;

[0010] S3, control the line-scan spectral camera to move axially above the end plug of the nuclear fuel rod to scan and detect the end plug part of the nuclear fuel rod;

[0011] S4, the system compares and processes the data obtained by pre-scanning and the data obtained by scanning and detecting, corrects the jumping error caused by the rotation of the nuclear fuel rod, and judges the defect condition of the end plug weld of the nuclear fuel rod according to the data obtained by scanning and detecting.

[0012] Specifically, the process of comparing and processing the data obtained by pre-scanning and the data obtained by scanning and detecting in step S4 includes:

[0013] Translate the point cloud data obtained by pre-scanning or the point cloud data obtained by scanning and detecting by a specified distance, and then splice the data with the point cloud data that has not been moved to form the point cloud data of the end plug weld part;

[0014] Wherein the specified distance Z of translation is X-d-Y, wherein X represents the mean value of the end of the unshifted point cloud data close to the shifted point cloud data, Y represents the mean value of the end of the shifted point cloud data close to the unshifted point cloud data, and d represents the set tolerance.

[0015] Specifically, the process of correcting the jumping error caused by the rotation of the nuclear fuel rod in step S4 includes:

[0016] Establish the rod body data reference of the nuclear fuel rod by the point cloud data of the end plug weld part, and correct the jumping error by subtracting the point cloud data obtained by scanning and detecting from the rod body data reference.

[0017] Specifically, the defect condition of the end plug weld of the nuclear fuel rod includes the width condition of the end plug weld, and the surface mechanical damage condition at the end plug weld.

[0018] Specifically, the process of judging the width condition of the end plug weld in step S4 includes:

[0019] Project the spliced point cloud data of the end plug weld part in the radial direction to obtain a detection projection image;

[0020] Then the average values of the specified number of data at the beginning and end of the end plug weld are calculated respectively, and they are taken as the end plug weld beginning platform reference value and the end plug weld end platform reference value respectively.

[0021] The difference between the end plug weld beginning platform reference value and the actual edge value of the detected projection image is used, and according to the set threshold, the first corresponding position where the difference value changes sign is found from the beginning of the projection data, so as to determine the starting value of the slope part of the end plug weld.

[0022] The difference between the end plug weld end platform reference value and the actual edge value of the detected projection image is used, and according to the set threshold, the first corresponding position where the difference value changes sign is found from the end of the projection data, so as to determine the ending value of the slope part of the end plug weld.

[0023] The width of the end plug weld is determined according to the starting value and the ending value of the slope part, and compared with the standard width of the end plug weld of the corresponding type of nuclear fuel rod, to judge the width condition of the end plug weld.

[0024] Specifically, the process of judging the surface mechanical damage condition of the end plug weld in step S4 is to detect whether there is a defect area near the end plug weld by using a machine vision algorithm, so as to judge the surface mechanical damage condition of the end plug weld.

[0025] Specifically, when it is judged that the surface of the end plug weld has mechanical damage in step S4, the size parameter of the mechanical damage is also calculated:

[0026] The data points in the specified range of the defect area are taken, and the defect area is sliced, and the depth parameter of the defect area is determined by the maximum value set of the sliced data.

[0027] The image of the defect area is stretched in combination with the projection image, and the length and width of the defect area are calculated and determined according to the image size after stretching and the image size of the point cloud data respectively.

[0028] Compared with the prior art, the present application has the following beneficial effects:

[0029] (1) The present application effectively eliminates the jumping error generated in the nuclear fuel rod rotation detection process by adjusting the design of the detection data process and the depth processing of the detection data without changing the equipment cost, and realizes the effect of improving the detection precision. The present application is simple and ingenious in design, easy to use, and suitable for application in nuclear fuel rod end plug weld defect detection. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 The present application is a whole flowchart of the embodiment. DETAILED DESCRIPTION

[0031] The application will be further described below in conjunction with the accompanying drawings and examples, and the embodiments of the application include but are not limited to the following examples.

[0032] Embodiment

[0033] As Figure 1 shown, the high-precision detection method for the end plug weld defect of the nuclear fuel rod comprises the following steps:

[0034] S1, when the nuclear fuel rod is placed on the end plug detection station, the clamping head device clamps the nuclear fuel rod from the rod body close to the end;

[0035] S2, pre-scanning: the clamping head device controls the rotation of the nuclear fuel rod, and controls the line-scan spectral camera to move above the rod body near the end plug of the nuclear fuel rod to pre-scan the nuclear fuel rod;

[0036] S3, control the line-scan spectral camera to move along the axial direction of the nuclear fuel rod to the position above the end plug to scan and detect the end plug part of the nuclear fuel rod;

[0037] S4, the system compares and processes the data obtained by pre-scanning and the data obtained by scanning and detecting, corrects the jumping error caused by the rotation of the nuclear fuel rod, and judges the defect condition of the end plug weld of the nuclear fuel rod according to the data obtained by scanning and detecting.

[0038] Specifically, the process of comparing and processing the data obtained by pre-scanning and the data obtained by scanning and detecting in step S4 comprises:

[0039] After the point cloud data obtained by pre-scanning or the point cloud data obtained by scanning and detecting is translated by a specified distance, the data is spliced with the point cloud data that is not moved to form the point cloud data of the end plug weld part;

[0040] Wherein the specified distance Z=X-d-Y of translation, wherein X represents the mean value of the end of the point cloud data that is not moved close to the point cloud data that is moved, Y represents the mean value of the end of the point cloud data that is moved close to the point cloud data that is not moved, and d represents the set tolerance, which is generally the mean value of multiple tolerances.

[0041] There is repetition in the point cloud data obtained by twice scanning of the spectral camera, and the value is artificially set, such as 1.7mm, and the width of each data acquisition of the known spectral camera is 1.92mm, which is determined by the specification parameter of the spectral camera. It is easy to deduce that the repetition width is 1.92-1.7=0.22mm, and after the overall translation of the point cloud data is completed by using the above translation method, the splicing algorithm is used to complete the splicing of the repeated data.

[0042] The combined spliced 3D point cloud data drawing and the plane drawing of the point cloud data can obtain a spliced picture without obvious splicing traces, and the splicing effect is relatively excellent. The repeated part of the point cloud data is calculated twice, so that the defect size and area calculated on the basis of the point cloud data are more accurate, and the translation of the data will not affect the depth calculation of the defect area.

[0043] Specifically, the process of correcting the runout error caused by the rotation of the nuclear fuel rod in the step S4 includes:

[0044] The rod body data reference of the nuclear fuel rod is established by the point cloud data of the end plug weld portion, the amplitude of the rod body is expanded (end plug amplitude / rod body amplitude) value, the expanded case fluctuation is more consistent with the end plug, and then the difference is made between the rod body data reference and the point cloud data obtained by scanning detection. At this time, the data after the difference is made is basically in the shape of a straight line except for the defect information, so that the interference of the runout error can be almost excluded, the runout error can be corrected, and better effect can be achieved.

[0045] Specifically, the defect condition of the end plug weld of the nuclear fuel rod includes the width condition of the end plug weld and the surface mechanical damage condition at the end plug weld.

[0046] Specifically, the process of judging the width condition of the end plug weld in the step S4 includes:

[0047] The point cloud data of the spliced end plug weld portion is projected in the radial direction to obtain a detection projection drawing;

[0048] Then, the average values of the specified number of data at the beginning and end of the end plug weld are calculated respectively, and the average values are taken as the end plug weld beginning platform reference value and the end plug weld end platform reference value respectively;

[0049] The end plug weld beginning platform reference value is subtracted from the actual value of the edge of the detection projection drawing, and the first corresponding position in the projection data from the beginning end according to the set threshold value is found, so that the starting value of the inclined portion of the end plug weld is determined;

[0050] The end plug weld end platform reference value is subtracted from the actual value of the edge of the detection projection drawing, and the first corresponding position in the projection data from the end according to the set threshold value is found, so that the termination value of the inclined portion of the end plug weld is determined;

[0051] The width of the end plug weld is determined according to the starting value and the termination value of the inclined portion, and compared with the standard width of the end plug weld of the corresponding type of nuclear fuel rod to judge the width condition of the end plug weld.

[0052] Take VertProjection0 as the projection array, a1 = VertProjection0 [0:9] the value of the first 10 points p1 = mean (a1) is the average of the first 10 points, plus threshold T, b = sgn (p1-VertProjection0-T), where sgn () indicates the sign of the bracket, find the first sign change position in b, which is the starting value of the inclined surface part. Similarly, the end value of the inclined surface part can be found.

[0053] Specifically, the process of judging the surface mechanical damage condition of the end plug weld in step S4 is to detect whether there is a defect area near the end plug weld by using a machine vision algorithm, so as to judge the surface mechanical damage condition of the end plug weld.

[0054] Specifically, in step S4, when it is judged that the surface of the end plug weld has mechanical damage, the size parameters of the mechanical damage are also calculated:

[0055] Take the data points in the specified range of the defect area, for example, 100 data points above and below the defect area, and slice the defect area, the depth measurement value of each slice is dis, and the corresponding maximum value is the deepest defect, ds represents the maximum value set of each slice of the entire defect, and the corresponding base is base0, each slice corresponds to a base, base0 is the set of bases, Grayval represents the scanning data, and the depth parameter of the defect area is determined by the maximum value set of the sliced data;

[0056] base = (Grayval [0] + Grayval [| Grayval |-1]) * 0.5

[0057] dis = Grayval-base

[0058] Take the image of the defect area and stretch it with the projection image, and calculate and determine the length and width of the defect area according to the image size after stretching and the image size of the point cloud data. Specifically, the value set base0 of base in the upper end plug image is consistent with the projection image of the upper end plug, wherein the horizontal width of the spliced picture is 3.62 mm, the horizontal stretching becomes 1048 points, and the defect occupies about 450 points, that is, 450*3.62 / 1048 = 1.5544 mm is the length of the detected defect; Similarly, the defect position of each slice occupies about 14 points, and the width is about 14*3.62 / 1048 = 0.048 mm. According to the third-party detected defect size data of 1.55 mm in length and 0.047 mm in width, it can be seen that the accuracy of the calculation method is very high, and the length and width of the stretched picture are corresponding.

[0059] Through the above process, the nuclear fuel rod end plug weld defect detection can be realized with high precision, and additional equipment cost is basically not needed.

[0060] The above embodiments are only preferred embodiments of the present application, and are not intended to limit the protection scope of the present application. Any change made on the basis of the design principles of the present application without creative labor shall fall within the protection scope of the present application.

Claims

1. A high-precision detection method for nuclear fuel rod end plug weld defects, characterized in that: The following steps are involved: S1. After the nuclear fuel rod is placed on the end plug inspection station, the clamping device clamps the nuclear fuel rod from the rod body near the end; S2. Pre-scanning: The chuck device controls the rotation of the nuclear fuel rod and simultaneously controls the line scan spectrum camera to move to the top of the nuclear fuel rod near the end plug to perform a pre-scan of the nuclear fuel rod; S3, controlling the line scan spectrum camera to move along the axial direction of the nuclear fuel rod to above the end plug to scan and inspect the end plug of the nuclear fuel rod; S4. The system compares and processes the data obtained from the pre-scan and the data obtained from the scanning test, corrects the runout error caused by the rotation of the nuclear fuel rod, and determines the defects of the nuclear fuel rod end plug weld based on the data obtained from the scanning test; The system performs data comparison processing on the data obtained from the pre-scan and the data obtained from the scan detection, including: The point cloud data obtained by pre-scanning or scanning is translated by a specified distance, and then joined with the unmoved point cloud data to form the point cloud data of the end plug weld. The specified translation distance Z = XdY, where X represents the average value of the end of the unmoved point cloud data close to the moved point cloud data, Y represents the average value of the end of the moved point cloud data close to the unmoved point cloud data, and d represents the set tolerance; The process of correcting the runout error caused by the rotation of the nuclear fuel rod includes: The point cloud data of the end plug weld is used to establish the rod body data benchmark of the nuclear fuel rod, and the runout error is corrected by subtracting the rod body data benchmark from the point cloud data obtained by scanning inspection. The defects of the nuclear fuel rod end plug weld include the width of the end plug weld and the surface mechanical damage of the end plug weld.

2. The high-precision detection method for nuclear fuel rod end plug weld defects according to claim 1, characterized in that: The process of determining the end plug weld width in step S4 includes: Project the point cloud data of the weld seam of the end plug after splicing in the radial direction to obtain a detection projection diagram; Then, a specified number of data at both ends of the end plug weld are taken to calculate the average value, and the average value is used as the platform reference value of the end plug weld at the beginning and the platform reference value of the end plug weld at the end respectively; The difference between the platform reference value at the head end of the end plug weld and the actual edge value of the detection projection is calculated, and the first corresponding position where the difference changes sign is found from the head end of the projection data according to the set threshold, so as to determine the starting value of the inclined portion of the end plug weld; The end value of the bevel part of the end plug weld is determined by subtracting the end platform reference value of the end plug weld from the actual edge value of the detection projection image and finding the first corresponding position where the difference changes sign starting from the end of the projection data according to the set threshold. The width of the end plug weld is determined based on the starting and ending values ​​of the inclined portion, and compared with the standard width of the end plug weld of a corresponding type of nuclear fuel rod to determine the width of the end plug weld.

3. The high-precision detection method for nuclear fuel rod end plug weld defects according to claim 1, characterized in that: The process of determining the surface mechanical damage condition of the end plug weld in step S4 is to use a machine vision algorithm to detect whether there is a defective area near the end plug weld, thereby determining the surface mechanical damage condition of the end plug weld.

4. The high-precision detection method for nuclear fuel rod end plug weld defects according to claim 3, characterized in that: In step S4, when it is determined that mechanical damage exists on the surface of the end plug weld, the size parameters of the mechanical damage are also calculated: Take the data points within the specified range of the defect area, slice the defect area, and determine the depth parameter of the defect area through the maximum value set of the slice data; The image of the defect area is taken and stretched in combination with the projection image, and the length and width of the defect area are calculated and determined according to the image size of the stretched image and the image size of the point cloud data.

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