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CN-121235998-B - Nondestructive testing method for internal pore volume of graphite component for nuclear reactor

CN121235998BCN 121235998 BCN121235998 BCN 121235998BCN-121235998-B

Abstract

The application relates to the technical field of computer industrial vision measurement, in particular to a nondestructive testing method for the internal pore volume of a graphite component for a nuclear reactor, which comprises the following steps that 1, an ultrasonic signal is transmitted to the graphite component, a pore distribution model of the graphite component is constructed based on an attenuation signal of the ultrasonic signal passing through the graphite component, and the pore distribution model comprises the probability of existence of pores in each region of the graphite component; and step 2, acquiring a three-dimensional CT scanning image of the graphite component, fusing the three-dimensional CT scanning image with a pore distribution model to obtain three-dimensional image information, slicing the three-dimensional image information into a plurality of groups of two-dimensional image information, and step 3, automatically dividing the two-dimensional image information based on an image segmentation algorithm to generate probability grades of each pixel point in the two-dimensional image information belonging to pores. By combining the advantages of ultrasonic scanning and CT imaging, the method remarkably improves the accuracy of nondestructive testing of the internal pore volume of the graphite component.

Inventors

  • LI JIAN

Assignees

  • 华清核测科技(苏州)有限公司

Dates

Publication Date
20260505
Application Date
20250911

Claims (9)

  1. 1. A method for non-destructive testing of the internal void volume of a graphite component for a nuclear reactor, comprising: Step 1, transmitting an ultrasonic signal to a graphite member, and constructing a pore distribution model of the graphite member based on an attenuation signal of the ultrasonic signal passing through the graphite member, wherein the pore distribution model comprises the probability of existence of pores in each region of the graphite member; Step 2, acquiring a three-dimensional CT scanning image of the graphite component, fusing the three-dimensional CT scanning image with a pore distribution model to obtain three-dimensional image information, and slicing the three-dimensional image information into a plurality of groups of two-dimensional image information; Step 3, automatically dividing the two-dimensional image information based on an image dividing algorithm to generate probability grades of each pixel point in the two-dimensional image information belonging to the pore, and converting the two-dimensional image information into a probability distribution image according to the probability grades of each pixel point belonging to the pore; step 4, processing the probability distribution image according to a growth algorithm, and extracting a pore area from the probability distribution image; Step 5, acquiring pore areas of all probability distribution images, restoring all probability distribution images into a three-dimensional measurement image based on a slicing mode of a three-dimensional CT scanning image, marking the pore areas in the three-dimensional measurement image, and calculating pore volume; step 2 comprises the following steps: Step 21, acquiring a three-dimensional CT scanning image P (x, y, z) of the graphite component, wherein x, y and z respectively represent coordinates of pixel points in the three-dimensional CT scanning image, and P represents pixel values of (x, y, z) positions; step 22, acquiring a pore distribution model E, and fusing the pore distribution model E and the three-dimensional CT scanning image P according to the space position to obtain three-dimensional image information PT (x, y, z); ; where PT (x, y, z) represents the pixel value of the three-dimensional image information PT at the (x, y, z) position, K represents the index of the acoustic wave frequency, K represents the total number of acoustic wave frequencies, Representing the probability of the distribution of (x, y, z) locations; step 23, dividing the three-dimensional image information PT (x, y, Z) into Z two-dimensional image information PQ (x, y) z , wherein Z represents an index of the two-dimensional image information PQ (x, y) z , Z represents a total number of pixel values in a height direction in the three-dimensional CT scan image P (x, y, Z), and PQ (x, y) z represents a pixel value of the Z-th two-dimensional image information at the (x, y) position.
  2. 2. The method of non-destructive testing of the internal void volume of a graphite component for a nuclear reactor of claim 1, wherein step 1 comprises the steps of: step 11, arranging N sound wave transducer groups on the front side surface and the rear side surface of the graphite component; n sound wave transducer groups are arranged on the left side surface and the right side surface of the graphite component; n sound wave transducer groups are arranged on the upper side surface and the lower side surface of the graphite component; Step 12, each sound wave transducer group mutually transmits sound wave information, and the attenuation coefficient of the mutually transmitted sound wave signals is calculated to obtain attenuation information; And 13, collecting attenuation information of each acoustic wave transducer group, calculating pore distribution probability of an influence area of each acoustic wave transducer group based on each group of attenuation information, and arranging the pore distribution probability of all the influence areas according to the spatial positions of the graphite members to form a pore distribution model.
  3. 3. The method of claim 2, wherein each acoustic transducer group corresponds to a regular predetermined area of the graphite member surface, the predetermined area having a size a; Each acoustic wave transducer group sequentially transmits ultrasonic signals with different frequencies to obtain attenuation coefficients with different acoustic wave frequencies, and the attenuation coefficients of the same acoustic wave transducer group under different acoustic wave frequencies are used as attenuation information of the acoustic wave transducer group.
  4. 4. The method for non-destructive testing of the internal void volume of a graphite component for a nuclear reactor according to claim 3, wherein step 13 comprises the steps of: step 131, inputting the attenuation coefficient of the same sound wave frequency into a pre-trained exponential regression model to obtain the distribution probability under the corresponding pore , Representing the distribution probability calculated by the kth sound wave frequency of the ith sound wave transducer group, i epsilon [1,3N ], when i epsilon [1, N ], The distribution probabilities calculated for the acoustic transducer groups on the front and back sides, i e N +1,2N, The calculated distribution probabilities for the acoustic transducer groups on the left and right sides, i e 2n +1,3n, Calculating the obtained distribution probability for the acoustic wave transducer groups on the upper side and the lower side; step 132, integrating all distribution probabilities The pore distribution model E is formed by arranging the graphite members in the spatial positions.
  5. 5. The method for non-destructive testing of the internal pore volume of a graphite component for a nuclear reactor according to claim 1, the method is characterized in that the step3 further comprises the following steps: step 31, predefining c category labels; step 32, randomly generating a plurality of cluster centers and membership matrixes in the two-dimensional image information, and carrying out iterative updating on the cluster centers and the membership matrixes based on fuzzy adjustment to generate category label distribution information of each pixel point in the two-dimensional image information; Each class label corresponds to a probability level representing that the pixel point belongs to the pore, and class label distribution information is converted into a probability distribution image TR.
  6. 6. The method of non-destructive testing of the internal void volume of a graphite component for a nuclear reactor of claim 5, wherein step 32 comprises the steps of: Step 321, predefining parameters including fuzzy weight m, first space function relative weight p, second space function relative weight q, smoothing parameter h, maximum iteration number T, non-membership parameter lambda, neighborhood window size d and termination threshold epsilon; Step 322, defining an initial cluster center V （0） and an initial membership matrix U （0） in the two-dimensional image information; step 323, according to the current cluster center V （t） and membership matrix Updating the temporary membership matrix ; T=0 at the first iteration; ; Wherein i ' represents indexes of pixel points in the two-dimensional image information, j ' and k ' represent indexes of class labels, j ' epsilon [1, c ], and k ' epsilon [1, c ]; In the t+1th iteration, the sample i 'belongs to the preliminary membership degree of the j' class label, n represents the total number of pixel points in the two-dimensional image information, and c represents the total number of class labels; Representing the Euclidean distance from pixel i 'to category label j', The Euclidean distance from the sample i 'to the category label k'; step 324, according to the temporary membership matrix Calculating an intuitive membership matrix ; ; ; ; ; The degree of hesitation is indicated by the expression, Representing the membership degree of the pixel point i 'to the class label j'; Representing an adjustment factor; Step 325, based on the intuitive membership matrix And a space function matrix H in the field of parameter H calculation; ; Representing the element values in the spatial function matrix H; represents a neighborhood window of d with the pixel point i' as the center, Representing the membership degree of the neighborhood pixel point z 'to the class label j'; Representing weight factors, z' representing indexes of pixel points in the neighborhood; ; h represents a smoothing parameter; ; step 326, based on the intuitive membership matrix Calculating an updated membership matrix by using the space function matrix H, the first space function relative weight p and the second space function relative weight q; representing normalization factors, exp representing an exponential function underlying a natural constant; ; ; Step 327, updating a clustering center according to the updated membership matrix; ; ; Step 328, checking iteration termination conditions, and if the iteration termination conditions are met, generating a pixel point i type label according to the final membership matrix U; a class label representing the i-th pixel; ; Each class label corresponds to a probability grade representing that the pixel point belongs to a pore, and class label distribution information is converted into a probability distribution image TR; the category label distribution information is converted into a probability distribution image TR.
  7. 7. The method of claim 6, wherein in step 328, the termination condition is: Condition 1: ; < epsilon, wherein, Representing the change amount of the membership matrix, Indicating that the maximum value is taken; Condition 2:t+1> T.
  8. 8. The method of non-destructive testing of the internal void volume of a graphite component for a nuclear reactor of claim 1, wherein step 4 comprises the steps of: step 41, acquiring a probability distribution image TR, and performing region growth on the probability distribution image TR to obtain a plurality of segmentation regions; Step 42, for each divided area, calculating an average pixel value of the divided area in the original two-dimensional image information, and if the average pixel value is lower than a preset selection threshold value, taking the divided area as a pore area; and 43, merging all pore areas, setting the pore areas as 1 and setting the rest areas as 0 in the original two-dimensional image information to obtain a binary image.
  9. 9. The method of non-destructive testing of the internal void volume of a graphite component for a nuclear reactor of claim 1, wherein step 5 comprises the steps of: step 51, acquiring a binary image of each two-dimensional image information, and acquiring the volume VT of a pixel point in the binary image in the real world; step 52, replacing the two-dimensional image information with the binary image, and restoring the two-dimensional image replaced with the two-dimensional image information into a three-dimensional measurement image in a mode of cutting the two-dimensional image information; and 53, marking the pore area by using pixel points with pixel values of 1 in the three-dimensional measurement image, obtaining the number G of all the pixel points marked as the pore area in the three-dimensional measurement image, and calculating the pore volume VH, wherein VH=G×VT.

Description

Nondestructive testing method for internal pore volume of graphite component for nuclear reactor Technical Field The application relates to the technical field of computer industrial vision measurement, in particular to a nondestructive testing method for the internal pore volume of a graphite component for a nuclear reactor. Background The statements in this section merely provide background information related to the present disclosure and may not constitute prior art. Graphite components are an important component of nuclear reactors. To ensure safe operation of a nuclear reactor, the internal porosity must be checked, including determining the presence of porosity, measuring the pore volume, and analyzing its distribution. Currently, the pore measurement of graphite members mainly adopts ultrasonic technology. The method judges the existence of the pore and estimates the volume and the range of the pore by analyzing the propagation characteristics (such as sound velocity, attenuation and the like) of ultrasonic waves in the component. However, this technique has a problem of insufficient accuracy in practical application. The ultrasonic wave can be influenced by pores in the member in the propagation process, and obvious scattering and attenuation phenomena are generated. The method can infer the distribution area of the pores approximately when the number of the pores is small and the distribution is concentrated, but in more general or complex cases, the method is difficult to accurately determine the volume of the pores and the distribution form of the pores cannot be accurately depicted. In summary, the existing method for detecting the internal pores of the graphite component based on ultrasonic waves has obvious limitations in quantitative measurement of pore volume and accurate judgment of distribution form, and the accuracy is required to be improved. Disclosure of Invention The summary of the application is provided to introduce a selection of concepts in a simplified form that are further described below in the detailed description. The summary of the application is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter. Some embodiments of the present application provide a nondestructive testing method for the internal pore volume of a graphite component for a nuclear reactor, so as to solve the technical problems mentioned in the background section. As a first aspect of the present application, some embodiments of the present application provide a method for non-destructive testing of an internal void volume of a graphite component for a nuclear reactor, comprising the steps of: Step 1, transmitting an ultrasonic signal to a graphite member, and constructing a pore distribution model of the graphite member based on an attenuation signal of the ultrasonic signal passing through the graphite member, wherein the pore distribution model comprises the probability of existence of pores in each region of the graphite member; Step 2, acquiring a three-dimensional CT scanning image of the graphite component, fusing the three-dimensional CT scanning image with a pore distribution model to obtain three-dimensional image information, and slicing the three-dimensional image information into a plurality of groups of two-dimensional image information; Step 3, automatically dividing the two-dimensional image information based on an image dividing algorithm to generate probability grades of each pixel point in the two-dimensional image information belonging to the pore, and converting the two-dimensional image information into a probability distribution image according to the probability grades of each pixel point belonging to the pore; step 4, processing the probability distribution image according to a growth algorithm, and extracting a pore area from the probability distribution image; And 5, acquiring pore areas of all probability distribution images, restoring all probability distribution images into a three-dimensional measurement image based on a slicing mode of the three-dimensional CT scanning image, marking the pore areas in the three-dimensional measurement image, and calculating the pore volume. By combining the advantages of ultrasonic scanning and CT imaging, the method remarkably improves the accuracy of nondestructive testing of the internal pore volume of the graphite component. Firstly, the probability distribution information (existence probability) of the internal pore of the component is rapidly acquired from a physical layer by utilizing ultrasonic scanning, high-resolution CT scanning is carried out on the basis, and the CT image processing process is restrained according to an ultrasonic model. The strategy overcomes the defects of the traditional ultrasonic method in quantitative and fine distribution judgment of the pore volume, and effectively avoids misjudgment caused