JP2008256603A - Nondestructive inspection device and non-destructive inspection method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a nondestructive inspection device and nondestructive inspection method capable of non-destructively detecting the degradation or breakage of a tubular analyte, before leakage occurs. <P>SOLUTION: This nondestructive inspection device comprises a radiation source for irradiating the tubular analyte with radiation from a side surface; an image sensor for acquiring a transmission image, by detecting the radiation having transmitted through the tubular analyte; an image information creating means for creating tube wall image information of the tubular analyte from the transmission image acquired by the image sensor; and an evaluating means for evaluating the integrity of the tubular analyte, based on the tube wall image information created by the image information creating means. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a non-destructive inspection apparatus and a non-destructive inspection method, and more particularly to a non-destructive inspection apparatus and a non-destructive inspection method capable of non-destructively inspecting defects due to thinning or corrosion of a tubular specimen.

  Various tubular bodies such as containers and pipes are used depending on the purpose for transporting and storing liquids and solids. Of these, containers, particularly drums, are used to pack and transport various products, whether liquid or solid. After achieving the purpose of transportation and storage, the drum can be appropriately removed from the residue, washed, shaped, painted and repaired, and recycled again as a product transportation and storage container.

  On the other hand, radioactive waste generated at facilities using nuclear fuel, hazardous wastes such as PCBs, and the like are now packed and stored in drums and square containers. Hazardous waste such as radioactive waste and PCB generated in nuclear fuel use facilities packed and stored in drums can be detoxified, or flammable and flame retardants can be incinerated, or metal In this case, it is buried after volume reduction processing such as ingot. In recent years, these processes cannot keep up and must be stored in drums. These drums are enormous in number, and in order to prevent damage to drums and leakage of contents due to long-term storage, it is necessary to detect deterioration of the container at an early stage and take measures such as refilling.

As a technique for inspecting leakage while evaluating the soundness of such a drum container, a technique using an ultrasonic flaw detector (see, for example, Patent Document 1), a foaming agent is applied to the surface, and pressure is applied. For example, a method for detecting a change occurring in the pressure sensor (for example, see Patent Document 2) or a method for detecting an air leaking from the drum can by inserting a drum can in a decompression container (for example, see Patent Document 3). ing.
JP 2004-28827 A JP-A-11-237302 JP 2000-55770 A

  However, in the above-described container inspection method, it is impossible to detect before leaking, it is difficult to identify the leaked part, and furthermore, measurement with a complicated content in the container is possible. There are issues such as difficulty.

  The present invention has been made to solve the above-described problems, and provides a nondestructive inspection apparatus and a nondestructive inspection method capable of nondestructively detecting deterioration or breakage of a tubular specimen before leakage occurs. With the goal.

  In order to achieve the above object, a nondestructive inspection apparatus according to an aspect of the present invention includes a radiation source that irradiates a tubular subject with radiation from the side, and an image that obtains a transmission image by detecting the radiation that has passed through the tubular subject. Based on a sensor, tube wall information generating means for generating tube wall information of the tubular subject from the transmission image obtained by the image sensor, and the tube wall information generated by the tube wall information generating means, Evaluation means for evaluating the soundness of the tubular specimen.

  The non-destructive inspection method according to another aspect of the present invention includes an irradiation step of irradiating a tubular subject with radiation from a side surface, and radiation transmitted through the tubular subject by irradiation of the radiation in the irradiation step using an image sensor. A transmission image acquisition step of detecting and obtaining a transmission image, a tube wall information generation step of generating tube wall information of the tubular subject from the transmission image obtained by the transmission image acquisition step, and the tube wall information generation step And an evaluation step for evaluating the soundness of the tubular subject based on the generated tube wall information.

  According to the present invention, it is possible to nondestructively detect deterioration or breakage of a tubular subject before leakage occurs.

  Below, the form for implementing this invention is demonstrated. The present invention is not limited to these embodiments.

(First embodiment)
FIG. 1 is a diagram schematically showing a main configuration of a nondestructive inspection apparatus according to the first embodiment of the present invention. FIG. 2 is a perspective view showing an outline of a configuration in which a drum can is used as a tubular specimen as an example of the nondestructive inspection apparatus according to this embodiment. FIG. 3 is a diagram showing a radiographic (X-ray) transmission image of a tubular subject. FIG. 4 is a diagram showing a line profile of a possible defect of a tubular specimen.

  As shown in FIG. 1, a nondestructive inspection apparatus 1 according to this embodiment includes a radiation source 3 that irradiates a tubular subject 2 with radiation from the side surface, a sensor 4 that detects radiation transmitted through the tubular subject 2, and A data acquisition unit 5 that converts transmission image data obtained by the sensor 4 into tube wall information data, a data processing unit 6 that evaluates a tubular object from the tube wall information data obtained by the data acquisition unit 5, and the result Is provided. As shown in FIG. 2, the nondestructive inspection apparatus 1 according to this embodiment includes a sorting device 8 that takes out a tubular specimen determined to have a defect, a shield 9 that shields radiation, and a tubular specimen. It is also possible to provide a tray 11 for placing the moving device 10 and the sorted tubular specimen.

  The tubular subject 2 refers to a tubular body to be examined. As the tubular subject 2, all tubular bodies that can obtain a transmission image of radiation using radiation (for example, X-rays or γ-rays) can be examined. Specific examples of such a tubular subject include tubular bodies such as tubular containers and piping. Examples of the tubular container include a drum can and a carton box.

  Any radiation can be used as the radiation applied to the side surface of the tubular subject 2 from the radiation source 3 as long as it passes through the tubular subject and the sensor 4 can obtain a transmission image. Examples of radiation include electromagnetic waves and particle beams. Examples of electromagnetic waves include X-rays and γ-rays. Examples of particle beams include α rays, β rays, and neutron rays. The radiation source 3 includes a collimator (not shown) that determines the direction of radiation.

Normally, when radiation, for example, X-rays or γ rays pass through a tubular subject, the amount of transmission changes according to the absorption coefficient and thickness of the material of the tubular subject. The transmission of X-rays or γ-rays through a tubular subject is defined as I ₀ when the intensity before entering the subject and I as the intensity after transmission.
I = I ₀ e ^−μρt (1)
It is represented by Here, μ (cm ² / g) is a mass energy absorption coefficient depending on the energy of X-rays or γ-rays, ρ (g / cm ³ ) is the specific gravity of the transmitted substance, and t (cm) is X-rays or γ-rays. Indicates the thickness through which is transmitted. When the amount of radiation (for example, X-rays or γ-rays) transmitted through the tubular subject 2 is small, for example, the amount of radiation (X-rays or γ-rays) from the radiation source 3 is increased. Can do.

  A sensor 4 for measuring a transmission image of radiation (for example, X-rays or γ-rays) that has passed through the tubular subject 2 performs imaging of X-rays or γ-rays used for, for example, medical diagnosis or industrial nondestructive inspection. When used, a combination of an X-ray film or a γ-ray film with a radiation intensifying screen can be used in order to improve the sensitivity of the photographing system. In this case, X-rays or γ-rays transmitted through the tubular specimen 2 are converted into photons or electrons by an intensifying screen, and the silver particles on the X-ray or γ-ray film are blackened by the photons or electrons. Thus, a transmission image of the tubular subject 2 can be obtained. In addition, for example, it is possible to scan a line sensor in synchronization with the passage of the tubular subject 2 using a line sensor, process the data, and reconstruct the transmission image. Thus, the sensor 4 can also use a sensor array.

  The data acquisition unit 5 that realizes the tube wall information generation unit is a signal conversion unit that converts transmission image data (electric signal, for example, NTSC signal) obtained by the sensor 4 into tube wall (image) information data (digital data). is there. Examples of the signal conversion means include an image processing board. The data acquisition unit 5 can also perform image data processing such as enhancing the contrast of the transmission image data obtained from the sensor 4 in order to facilitate the determination in the data processing unit 6.

  The data processing unit 6 that functions as an arithmetic processing unit that realizes the evaluation unit is a signal processing unit that evaluates the tubular specimen (determines whether there is a defect) from the tube wall information data acquired by the data acquisition unit 5. In the data processing unit 6, for example, the tube wall thickness is evaluated from the tube wall information of the tubular subject, and compared with the tube wall thickness (normal value) of the tubular body obtained in the normal case, for example, processing such as subtraction. And determine the defect from the result. The tube wall information (data) of a normal tubular body may be digital data that is measured in advance and stored (accumulated) in a digital data memory unit (not shown) of the data processing unit 6.

  The display device 7 displays these results. When the tubular subject is a tubular container (for example, a drum can), the sorting device 8 takes out the tubular container determined to have a defect. The shield 9 can be made of a material capable of shielding radiation. For example, when the used radiation is X-ray or γ-ray, it can be made from lead or a thick iron plate, and when the used radiation is neutron beam, it can be made from a concrete plate or the like.

  Next, a transmission image of the tubular subject in this embodiment and tube wall information data (digital data) from the transmission image will be described based on FIGS. 3 and 4. FIG. 3A is an example of a transmission image taken by irradiating X-rays on the lateral wall portion of the drum can with the tubular specimen as a drum can. FIG. 3B is a line profile in which a horizontal distribution of luminance values (digital values indicating brightness) in a portion surrounded by an ellipse in FIG. Since the X-ray transmittance is highest up to the outer wall portion of the drum, the luminance is high, and the X-ray transmittance is lowest at the inner wall portion of the drum. Accordingly, the distance from the highest brightness to the lowest brightness in FIG. 3B corresponds to the wall thickness (T) of the drum can wall.

  There are various causes of defects in the tubular specimen. For example, it may be due to thinning of the tube wall, but the surface may be uneven, such as corrosion. Furthermore, an oxide film may adhere to the tube wall and the apparent tube wall may become thick. Examples of defects of these tubular specimens will be described with reference to FIG. FIG. 4 is a diagram illustrating an example of a defect assumed for a tubular specimen (for example, a drum can). FIG. 4A schematically shows an X-ray or γ-ray transmission image of a tube wall portion of a drum can when a drum can is used as a tubular subject. As understood from the measurement result of FIG. 3, since the inner wall portion of the drum can has the largest thickness, the amount of transmitted X-rays or γ-rays is reduced and darkened.

  4 (b) to 4 (e) are plots of the relationship between the luminance value and the position in the region 12 surrounded by the broken line in FIG. 4 (a), in the normal case and in the case of each defect. It is a line profile of the luminance value shown. FIG. 4B shows a case where the tubular specimen (drum can) is normal. The outside of the drum can is bright because there is no X-ray or γ-ray absorber (the luminance value is high), and when it reaches the outer wall of the drum, the thickness gradually increases from the outer wall to darken. The darkest part is the inner wall, after which the thickness decreases again, and finally becomes nearly constant. The distance between the outer dark part and the darkest part corresponds to the wall thickness. FIG. 4C to FIG. 4E are examples when the tubular specimen (drum can) has a defect. FIG. 4C shows the case where the tube wall thickness of the drum can is extremely small. In this case, the width from the portion where the luminance value of X-rays or γ-ray is the highest (brighter) to the portion where the luminance value is the smallest (darker) becomes narrower. FIG. 4D shows a case where the thickness is non-uniform because corrosion, for example, rust is generated on the inner wall of the drum. As described above, the thickness of the drum can wall is non-uniform, so that the intensity of transmitted X-rays or γ-rays varies greatly. FIG. 4E shows the case where the drum can is thinned and an oxide film adheres to the inner wall thereof. Since the density of the oxide film is usually smaller than the density of the drum can, the line profile spreads by the thickness of the deposited oxide film at a brightness value higher than the brightness value of the drum can.

Next, the operation of the nondestructive inspection in this embodiment will be described using the nondestructive inspection apparatus of FIG. In the nondestructive inspection apparatus 1, the tubular subject (drum can) 2 (2 a to 2 d) is carried into the shield 9 by the tubular subject moving device 10. Within the shield 9, radiation (for example, X-rays or γ-rays) emitted from the radiation source 3 is irradiated. The sensor 4 obtains a transmission image (data) of radiation corresponding to the shape of the tubular subject as shown in FIG. 4A, and the data acquisition unit 5 transmits the radiation as shown in FIGS. 4B to 4E. Tube wall information data (digital image data) indicating the X-ray intensity or transmitted γ-ray intensity is obtained. The tube wall information data (digital image data) thus obtained is compared and evaluated by the data processing unit 6 with, for example, normal digital image data stored (stored) in advance. The criterion for determining the presence or absence of a defect can be determined according to the target defect. For example, when it is desired to mainly determine the thinning as shown in FIG. 4C, the thickness is used as a determination index. When the corrosion (eg, rust) as shown in FIG. Alternatively, a method such as detecting a change (for example, a change rate) of tube wall information data indicating transmitted γ-ray intensity with respect to the normal time can be considered. The result determined in the data processing unit 6 is displayed by the data display unit 7. Further, the result determined by the data processing unit 6 is transmitted to the sorting device 8, whereby the sorting device 8 is driven to move only the defective tubular subject 2 c to the tray 11.
In such a non-destructive inspection, the range that can be evaluated at one time is a part of the tube wall of the tubular subject, but the subject 2 is rotated and / or moved, or the radiation source 3 that irradiates the radiation By moving the sensor 4, it is possible to perform an arbitrary portion along the longitudinal direction and the outer peripheral portion of the tube wall of the tubular subject. Further, it can be performed by paying attention to the most prone defect part of the tubular specimen, for example, a joint portion of the tube wall, and can also be performed at a plurality of locations of these tube wall portions. Further, if necessary, it can be performed over the entire tube wall portion along the longitudinal direction and the outer peripheral portion of the tube wall portion of the tubular subject.

Furthermore, the operation of the nondestructive inspection in this embodiment will be described based on FIG. FIG. 5 is a flowchart showing one procedure of nondestructive inspection in this embodiment.
First, a transmission image of the tubular subject 2 is taken (FIG. 5, Step 1 (hereinafter referred to as “S1”)). This transmission image (for example, a transmission image (data) as shown in FIG. 3A) can be obtained by the sensor 4.
Next, the data acquisition unit 5 converts such transmitted image data into luminance data (digital image data) indicating transmitted X-ray intensity or transmitted γ-ray intensity (FIG. 5, S2). By this conversion, for example, digital image data indicating transmitted X-ray intensity or transmitted γ-ray intensity as shown in FIGS. 3B and 4B to 4E can be obtained.

  On the other hand, a transmission image of a normal sample (normal tubular body) is taken (FIG. 5, S11). This transmission image is similarly converted into luminance data (digital image data) indicating transmission X-ray intensity or transmission γ-ray intensity (FIG. 5, S12). As the luminance data of these normal samples, the luminance data measured in advance can be stored (accumulated) in, for example, a digital image memory unit (not shown), and the luminance data can be used.

  Next, the data processing unit 6 derives (determines) a determination index for comparing the luminance data of the tubular subject with the luminance data of the normal sample (S3 in FIG. 5). A determination index for determining the presence or absence of a defect in a tubular specimen (for example, a drum can) can be determined in accordance with the target defect. For example, when it is desired to mainly determine the thinning as shown in FIG. 4 (c), the thickness is used as a determination index, and corrosion (for example, rust) as shown in FIG. 4 (d), or FIG. 4 (e). When it is desired to determine the thinning of the tubular specimen 2 and the adhesion of the oxide film to the inner wall of the tube, the change of the digital image data indicating the intensity (luminance) of transmitted X-rays or transmitted γ-rays is detected. The method of doing etc. can be considered. These determination indexes may be any of those described above, and these determination indexes may be used in combination.

Based on this determination index, the data processing unit 6 determines the presence or absence of a defect in the tubular specimen (drum can) based on whether or not a determination reference value of the determination index exceeds a predetermined threshold (for example, t1) (FIG. 5). , S4). Specifically, for example, difference data between digital image data of a tubular subject and digital image data of a normal tubular body is taken, and determination is made based on whether the difference data exceeds a predetermined threshold value. The predetermined threshold value can be determined according to the type, material, or determination index of the tubular subject.
The determination of the presence / absence of a defect in the tubular specimen (drum can) is made based on a determination reference value as to whether it is less than another predetermined threshold (for example, t2) instead of the determination reference value for exceeding a predetermined threshold (for example, t1). You may determine based on. Further, both of these cases, that is, the case where both exceed a predetermined threshold value (for example, t1) and the case where it is less than another predetermined threshold value (for example, t2), are used as judgment criteria (values) for the presence or absence of defects in the tubular specimen. It may be used.
Further, the predetermined threshold can be a two-stage threshold. For example, if the first-stage threshold value (for example, t1 ′) is exceeded, the tubular specimen is considered to be in a dangerous state (warning state), and the second-stage threshold value (for example, t1) larger than the first-stage value is exceeded. In some cases, it is possible to determine that the tubular subject is abnormal.

  For example, when the amount of thinning is used as a determination index, the predetermined threshold can be a thinning of 50% of the thickness of the tube wall of a normal tubular body. For example, when the thickness of the tube wall of a drum that is a tubular subject is 1.2 mm, the threshold value can be 0.6 mm. In this case, when the evaluation result of the wall thinning amount of the tubular specimen (drum can) exceeds 0.6 mm (when it becomes thinner than that), it can be determined that the tubular specimen (drum can) is defective. .

  The result determined in the data processing unit 6 is displayed by the data display unit 7. When the data processing unit 6 determines that the determination index (evaluation result) of the tubular subject 2 does not exceed the previously obtained threshold indicating the range of abnormality, it is determined as normal and the nondestructive inspection is performed. The process ends (FIG. 5, S5). When the data processing unit 6 determines that the determination index (evaluation result) of the tubular subject 2 exceeds a predetermined threshold value and is abnormal (FIG. 5, S13), the resulting signal is sent to the sorting device 8. And the sorting device 8 is driven to sort only the defective tubular object (drum) 2c (FIG. 5, S14). The sorted tubular specimen (drum can) 2 further repackages the contents or further wraps the tubular specimen (drum can) in another container according to, for example, the degree of abnormality or the type of the contents (for example, two Such as a heavy drum can be performed (FIG. 5, S15).

  According to the present embodiment, a defect in a tubular subject can be found and treated quickly, in a non-destructive manner, and in a state before leakage occurs.

(Second Embodiment)
Next, a second embodiment of the present invention will be described with reference to FIG. FIG. 6 is a diagram showing a difference from the normal time of digital data indicating the radiation intensity distribution transmitted through the tube wall of the tubular subject acquired by the data acquisition unit 5.

In the case of a tubular specimen (for example, a drum can) of the same material and shape, if the tubular specimen is normal (when there is no problem), the difference approaches zero as much as possible. However, when thinning, rust, corrosion, or the like occurs, the variation (fluctuation) in the difference increases. For example, when the thickness is reduced, the radiation transmission intensity at the location where the thickness is reduced increases. Therefore, when the difference from the normal time is taken, the difference in luminance on the image becomes a positive (+) value. . In addition, when an oxide film or the like is attached, the transmitted radiation intensity decreases as the thickness increases, and a negative (-) value is obtained if the difference from the normal time is taken.
Therefore, for example, as shown in FIG. 6A, the maximum value (variation range) of the difference in the difference in the radiation intensity distribution (luminance data) of the tubular subject is a predetermined threshold (for example, ± t1) having a predetermined width. ) (That is, when the threshold value (+ t1) is exceeded and / or when it is less than the threshold value (−t1)). In addition, the predetermined threshold value can be set such that the upper threshold value and the lower threshold value are different from each other (for example, + t1 and -t2).
Furthermore, the predetermined threshold value can be determined as described in the first embodiment. Further, as shown in FIG. 6B, the predetermined threshold can be a first threshold (for example, ± t1 ′) and a second threshold (for example, ± t1). When the predetermined threshold value (eg, ± t1 ′) of the first stage is exceeded, the tubular subject is determined to be in a dangerous state (warning state), and the predetermined threshold value (eg, ± t1) of the second stage is exceeded. Alternatively, it can be determined that the tubular subject is abnormal.

  According to the present embodiment, it is possible to detect a defect in a tubular subject more accurately and non-destructively and quickly and in a state before leakage occurs.

(Third embodiment)
Next, a third embodiment of the present invention will be described with reference to FIG. FIG. 7 is a diagram obtained by measuring and plotting a defect determination index of a tubular specimen at regular time intervals. The defect determination index may be, for example, the thickness of the tubular specimen, or the difference data between the radiation intensity distribution transmitted through the tube wall of the tubular specimen and the radiation intensity distribution of the normal tubular body, or the fluctuation thereof. it can.

  Thinning, rust, corrosion, etc. progress gradually over time. Therefore, the relationship between the elapsed time and the determination index is obtained, and the lifetime of the tubular subject can be predicted from the extrapolation (that is, the slope (tilt angle) of the line obtained from the plot data of the relationship between the elapsed time and the determination index). For example, in FIG. 7A, a point in time when a predetermined threshold value that has been determined in advance is defined as the lifetime, and the tubular specimen is replaced by then. At the time of examination, ranking can be made according to the predicted life of each tubular specimen, and the priority of replacement can be determined. FIG. 7B shows a measurement index (determination result) of a defect in a tubular specimen measured at regular intervals using the thickness of the tubular specimen as a judgment index. The extrapolated value predicted from these plots is defined as a predetermined threshold, for example, 50% of the thickness of a normal tubular body. ).

  Further, when the variation in the difference between the radiation intensity distribution of the tubular subject and the radiation intensity distribution of the normal tubular body is used as a determination index, for example, in the tubular subject (drum can), the variation in the difference when initially measured is changed. The largest point can be used as a measurement location. Moreover, the measurement location may be measured not at one location but at a plurality of locations (for example, 30 locations), and an average of fluctuations of these differences may be obtained. If necessary, it is also possible to measure the entire variation of the difference over time at each of these plurality of locations over time and predict the life (replacement time) using a three-dimensional graph.

For example, in the case of drums such as nuclear fuel waste, there are many drums to be inspected, and replacement work is not easy. In that case, even if an abnormal tendency is found, it is not possible to exchange everything immediately. Therefore, it is necessary to rank the drum cans according to the degree of abnormality, and replace them with priority from the urgent ones. However, at present, this determination can be made only by visual inspection of the appearance.
As described above, according to the present embodiment, it is possible to accurately identify a tubular subject that is highly urgent to replace even if there is no abnormality in appearance, and the safety of management of the tubular subject is improved. .

(Fourth embodiment)
Next, a fourth embodiment of the present invention will be described with reference to FIG. FIG. 8 is a diagram illustrating an example of the configuration of the sensor in FIG. 1. In FIG. 8, the sensor 4 includes a scintillator 12 that reacts with radiation (for example, X-rays or γ-rays) and emits light according to the intensity, a light shielding cover 13, a lens 14, and a camera 15. The scintillator 12 emits light according to the intensity of the radiation transmitted through the tubular subject 2, and the light is collected by the lens 14 and photographed as an image by the camera 15.

The scintillator 12, for example, _{NaI (Tl), CsI (Tl} ), LiI (Eu), CaF 2 (Eu), BaF 2, CeF 3, Bi 4 Ge 3 O 12, Gd 2 O 2 S (Tb), Gd ₂ O ₂ S (Eu), Gd ₂ SiO ₅ (Ce), Lu ₂ SiO ₅ (Ce), PbWO ₄ , CdWO ₄ , YAP (Ce), CsF, LuAlO ₃ (Ce), Lu ₃ Al ₅ O ₁₂ ( Yb), Lu ₃ Al ₅ O ₁₂ (Pr), LiF (W), ZnS (Ag), PWO, and other light emitters can be used.
As the camera 15, for example, an imaging device such as a CCD camera, a CMOS camera, or a flat panel can be used. Alternatively, the camera 15 may be a line sensor or a line camera, and data may be acquired while moving the tubular subject 2 or the sensor 4, and a two-dimensional image may be obtained by performing necessary processing on the data and reconstructing the data. Is possible.

  According to the present embodiment, it is possible to acquire luminance data more quickly and accurately than when digitally processing an image shot with a film or the like.

(Fifth embodiment)
Next, a fifth embodiment of the present invention will be described. In this embodiment, an X-ray image intensifier (hereinafter referred to as “X-ray II”) is used for the sensor 4. X-ray I. Converts the light (signal) of the scintillator into an electrical signal (for example, (light) electrons) according to the intensity, and amplifies the signal by accelerating it, and the amplified signal is converted into light again by the output phosphor. It becomes the composition to convert. X-ray I.D. I. By using, measurement can be performed with high sensitivity even when transmitted X-rays or transmitted γ-rays are weak.

  According to the present embodiment, since the sensitivity of the sensor is high, the irradiation dose can be kept low, and the system such as power consumption and shield weight can be manufactured economically. In addition, when an X-ray source or a γ-ray source having the same irradiation dose (output) is used, it is possible to cope with a larger tubular subject.

(Sixth embodiment)
Subsequently, a sixth embodiment of the present invention will be described with reference to FIG. FIG. 9A is a diagram illustrating an image obtained by performing a subtraction process on two images photographed under the same conditions as those in FIG. 3 or FIG. As shown in FIG. 9C, two brightness value line profiles similar to those in FIG. 3 or FIG. 4 are obtained at a position slightly shifted (separated from each other) by a predetermined position. By subtracting the line profiles of these two luminance values (subtraction), it is possible to obtain tube wall image data (line profile) in which the edge portion is emphasized. For example, when the data acquisition unit 5 subtracts the line indicated by the broken line from the line indicated by the solid line out of the two data line profiles shown in FIG. A line profile in which the edge portion is emphasized as shown in (b) can be obtained. By performing subtraction in this manner, the edge portion of the tube wall of the tubular subject is emphasized, and the defect of the tubular subject can be easily determined. Note that the position of the line profile of these two luminance values (position slightly shifted by a predetermined position) for obtaining a line profile in which the edge portion is emphasized is the thickness of the tube wall of the tubular subject, etc. Can be easily determined according to

It is also possible to determine a defect by directly visually observing a subtraction image obtained by taking a difference between digital image data of a normal tubular subject from digital image data of a tubular subject to be judged. For example, in the normal case, by subtracting the digital image data of the normal tubular body from the digital image data of the tubular subject (subtraction), the normal portion has a constant luminance, but if there is an abnormality, If there is a bulge, it will be close to black (the luminance value will be small), and if there is a dent due to thinning, etc., it will be close to white (the luminance value will increase), making it easier to find defects in the tubular specimen. Become. However, when the original data to be subtracted is reversed, white and black are reversed, white is displayed in black, and black is displayed in white.
Therefore, when the defect of the tubular specimen is large, it is possible to determine the defect of the tubular specimen by visual observation (visibility).

  According to the present embodiment, it is possible to determine the defect of the tubular subject more accurately.

(Seventh embodiment)
Subsequently, a seventh embodiment of the present invention will be described with reference to FIGS. In this embodiment, a color X-ray image intensifier (“Color II (registered trademark)” (hereinafter referred to as “Color II”) is used as the sensor 4. 10 shows a color I.D. which is another example of the configuration of the sensor in FIG. I. It is a figure which shows typically the principal part structure of this. As shown in FIG. I. Includes a scintillator 16 that reacts with radiation (for example, X-rays or γ-rays) to emit light according to intensity, a photoelectric film 17 that converts emitted light (signal) into an electric signal (photoelectron), and an electric signal (photoelectron). Is composed of an electron lens 18 that amplifies (accelerates) the light, an output phosphor 19 that converts the amplified (accelerated) electrical signal (photoelectrons) into light (signal) again, and a camera 20 that captures the emitted light. Color I.I. I. Is basically a normal X-ray I.I. I. A scintillator that emits color light is used for the output phosphor portion in Fig. 2, and the image is taken with an imaging device such as a color camera. Examples of the output phosphor include Y ₂ O ₂ S (Eu). A CCD camera, a CMOS camera, or the like is used as the imaging device. The color I.D. I. Then, by appropriately combining the light emission characteristics of the scintillator 16 and the sensitivity characteristics of the camera 20, it becomes possible to change the sensitivity to X-rays or γ-rays for each RGB component, and simultaneously using each of the three RGB components. It has the feature that a wide dynamic range can be obtained by displaying.

For example, color I.O. using Y ₂ O ₂ S (Eu). I. Then, when X-rays or γ-rays having the same energy and intensity are irradiated, the red region emits the strongest light, and then the light emission decreases in the order of green and blue. If this is photographed with a color camera having high sensitivity in the red region, red is the most sensitive to X-rays or γ-rays, and then the sensitivity decreases in the order of green and blue. Therefore, when photographing a large X-ray or γ-ray absorption difference at the same time, the X-ray or γ-ray absorption amount is a red component and the X-ray or γ-ray absorption amount is a blue component. By shooting, it is possible to widen the dynamic range that can be shot at once.
Specifically, for example, when Y ₂ O ₂ S (Eu) is used as the output phosphor, the ratio of the emission color differs by using different Eu concentrations. By adjusting the amount of R, G, and B light emission according to the sensitivity characteristics of the camera's CCD imaging device, the signals of R, G, and B with different sensitivities depending on the intensity of incident X-rays or γ-rays can be obtained. Is converted and the dynamic range of the measurement is expanded. This is achieved by the radiation source 4 having an adjustment mechanism that adjusts the light emission amounts of the three primary colors of the light so that the measurement range of the camera is expanded. Monochrome has only one characteristic curve as shades of white to black, but in the case of color, it can have three characteristic curves as the shades of R, G, and B of the three primary colors of light. The R, G, and B components have different characteristics and can be displayed simultaneously by color. Therefore, color I.I. In I, the dynamic range can be widened.

  For example, FIG. 11 shows a photographing example of a drum can containing contents. As shown in FIG. 11, the transmission image is divided into three color components of RGB (red, green, and blue). 11 (a), (b) and (c) show the color I.D. I. The transmission image data of the tubular specimen (drum can) obtained in (1) is shown for each RGB component. Since the R component has the highest sensitivity and the B component has the lowest sensitivity, in the case of the R component data in FIG. 11 (a), the wall portion is not completely saturated, but FIG. This is clearly shown in the B component data of c). However, in the low-sensitivity B component, the portion of the content that absorbs a large amount of X-rays or γ-rays is completely blacked out and cannot be discriminated. Thus, since it has three components with different sensitivities, it has a feature that it can simultaneously photograph an object with a large absorption difference.

  Here, an example in which this feature is utilized for measuring the wall thickness of the tube wall will be described with reference to FIG. FIG. I. It is a figure which shows the example of evaluation of the tube wall thickness using. The left image in FIG. 12 is a transmission image of the X-ray or γ-ray of the tube wall portion. A plot of the luminance distribution (digital image data distribution) of the portion surrounded by an ellipse for each RGB component is shown on the right side. When evaluating the wall thickness, it is necessary to accurately determine the inner wall position where the luminance decreases most and the outer wall position where the luminance increases and becomes constant. When the three components are compared, the inner wall position can be clearly seen in the R component, but the outer wall position is completely saturated and cannot be clearly determined. On the contrary, in the B component, the outer wall position is clear, but the inner wall position is crushed and unclear.

  Monochrome X-ray I. Is used when there is only one component of RGB. In this case, it is difficult to clearly photograph the inner wall portion and the outer wall portion at one time for the above reason. However, the color I.D. I. By appropriately using the three components, in the R (red) component having a high radiation absorption rate, the inner wall portion of the tubular subject having a large amount of X-ray or γ-ray absorption is clearly recognized, In the B (blue) component having a low absorption rate, it is possible to clearly recognize the outer wall portion of the tubular subject having a small amount of X-ray or γ-ray absorption. Thickness) can be measured more accurately.

  According to this embodiment, normal X-ray I.D. I. In the case of evaluating the wall thickness of a tube wall that is easily saturated and difficult to evaluate, the color I.D. I. By using, more accurate evaluation becomes possible.

  Next, an eighth embodiment of the present invention will be described with reference to FIG. FIG. 13 is a diagram showing the concept of nondestructive inspection using the correction member according to the eighth embodiment of the present invention. In non-destructive inspection using radiation (for example, X-rays or γ-rays), X-rays or γ-rays wrap around areas where the thickness of tubular specimens that transmit X-rays or γ-rays is extremely different. A phenomenon called halation is caused and the tube wall of the tubular subject cannot be observed accurately. In the non-destructive inspection, it is necessary to take a clearer image of the wall of the container, but this halation phenomenon is an obstacle. When halation occurs, the radiation that passes through the portion where the radiation is easily transmitted (outer wall portion of the tubular subject) wraps around the rear side of the tubular subject, and the tube wall portion of the tubular subject appears to be thinner than the actual thickness. Tend. Therefore, by applying the correction member 21 as shown in FIG. 13, there is an effect of clearly obtaining an image inside the wall surface.

  The correction member 21 transmits radiation (for example, X-rays or γ-rays), and the sensor 4 transmits transmitted radiation (for example, transmission X-rays or transmission γ-rays) transmitted through the tubular subject and the correction member 21. It consists of a detectable material. The correction member 21 is a material in which the difference between the portion having the highest transmitted radiation intensity such as the vicinity of the outer wall and the lowest portion such as the inner wall is within a predetermined range, that is, within a range that is not too large and not too small. Those consisting of are preferred. The material of the correction member 21 can be determined by the size and material of the tubular subject and the type of radiation used. For example, as an easy-to-understand example, the outer diameter of an iron tube is 150 mm and the wall thickness is 10 mm. In this case, the distance through which the X-rays and γ-rays pass through the inner iron portion is the longest at the inner wall tangential portion, about 80 mm, and the outer wall portion is close to 0 mm. Therefore, on the image, the brightness distribution of the transmitted X-rays or γ-rays of the inner wall portion whose distance of transmission from the outer wall portion where the transmission distance of X-rays or γ-rays is close to 0 mm is 80 mm. Depending on the energy of X-rays and γ-rays, the transmission luminance is different between the outer wall portion and the inner wall portion, but the difference in luminance value is reduced by inserting the correction member 21 and reducing the difference between 0 mm and 80 mm thickness, Halation is less likely to occur.

  According to this embodiment, it is possible to avoid the fogging or halation phenomenon and to clearly photograph the tube wall portion of the tubular subject.

  Next, a ninth embodiment of the present invention will be described with reference to FIGS. FIG. 14 shows a concept of an application method of stereo photography known as a three-dimensional photography method applying the principle of triangulation (the principle of stereoscopic vision of human eyes) according to the ninth embodiment of the present invention. FIG. In FIG. 14, it is assumed that an image in which the contents 22 are put in the tubular subject (drum can) 2 is photographed for easy understanding.

A transmission image obtained by a system with one normal radiation source 3 and one sensor 4 can only obtain a planar image in which the inner wall of the drum and the contents 22 are overlapped. I don't know where it was placed. Therefore, when a plurality of radiation sources 3 and sensors 4 are arranged and the same image is taken, even if the same image is taken, different images are obtained due to different shooting directions. Obtaining a stereoscopic image (that is, a stereo image) from a plurality of (two) two-dimensional images is generally known as a stereo imaging method, and in this case, the difference between the two images Is called parallax. When the portion of interest is convex or concave, the difference in the height of the bulge or dent appears as a difference in parallax. Accordingly, the size of the bulge or dent can be measured by obtaining the difference in parallax and evaluating the difference in parallax. Specifically, for example, so-called stereo matching processing is performed on two images to obtain an image having a distance (depth) value, that is, a distance image (three-dimensional image information).
In addition, by processing (synthesizing) two images by such a stereo photographing method to form a stereoscopic image, the shape information can be clearly displayed when a person visually determines a defect. .

Here, an example in which this feature is used for measuring the tube wall of a tubular subject will be described with reference to FIG. FIG. 15 is an enlarged view of the measurement unit in the measurement of the detection target portion (of the tube wall) of the tubular subject using the stereo imaging application method according to this embodiment.
First, the detection target part of the tubular subject (drum can) is irradiated with radiation from a plurality of (two) predetermined side directions, and the radiation transmitted through the detection target part is detected. Acquire (two) transparent images. In FIG. 15, the radiation (radiation paths α1, α2) to be irradiated is shown by a single broken line, but each radiation is irradiated including the entire range of the detection target portion. Next, the data acquisition unit 5 (not shown) calculates the parallax from these two transmission images. A difference in parallax is obtained from the obtained parallax, and a distance image (three-dimensional image information) of the detection target portion of the tubular subject is acquired. Specifically, for example, for these two transmission images, a stereo matching process is performed in which a corresponding area is specified by calculating a city block distance for each small area of each image and obtaining a correlation with each other. A distance image (three-dimensional image information) obtained by digitizing perspective information from a pixel shift generated according to the distance of the object to the target object is acquired. As shown in FIG. 15, this distance image information includes information on a detection target portion (of the tubular subject) related to the normal direction (direction orthogonal to the tangent to the tube wall) (W) of the peripheral surface of the tubular subject, This is three-dimensional image information having information on the detection target portion regarding the tangential direction (the (depth) direction along the tangent to the tube wall) (L), that is, distance value information (distance information). . On the other hand, for a normal sample (normal tubular body), a plurality of (two) predetermined transmission images of the detection target portion are acquired in the same manner, and a distance image (three-dimensional image) of the normal tubular body is obtained from these transmission images. Information).

In the data processing unit 6 (not shown), the difference between the distance image data of the detection target portion of the tubular subject and the distance image data of the detection target portion of the normal tubular body is obtained. As a result, it is possible to determine which part in the tangential direction (direction along the tangent to the tube wall) of the peripheral surface of the tubular subject is a defect portion of the detection target portion of the tubular subject based on the distance information (for example, L1 in FIG. As described above, in addition to the normal direction of the peripheral surface of the tubular subject, the tangential direction of the peripheral surface of the tubular subject can be evaluated for the defective portion of the detection target portion of the tubular subject.
As shown in FIG. 14, the radiation source 3 that irradiates the detection target portion of the tubular subject (drum can) from a plurality of different predetermined side directions is irradiated using a plurality of radiation sources 3a and 3b. Irradiation may be performed by moving one radiation source 3. Similarly, the sensor 4 corresponding to the radiation source 3 may be a plurality of sensors 4 a, 4 b, or the sensor 4 may be moved corresponding to the movement of one radiation source 3.
By detecting a tube wall using a radiation source that irradiates from a plurality of predetermined lateral directions and a sensor corresponding thereto, the detection target portion related to the normal direction of the peripheral surface of the tubular subject. In addition to this information, it is possible to obtain information on the detection target portion regarding the tangential direction of the peripheral surface of the tubular subject.

  According to the present embodiment, with respect to the tube wall image information, in addition to information on the detection target portion regarding the normal direction of the peripheral surface of the tubular subject, information on the detection target portion regarding the tangential direction of the peripheral surface of the tubular subject is included. Therefore, the soundness of the tubular specimen can be more accurately evaluated.

It is a figure which shows typically the principal part structure of the nondestructive inspection apparatus which concerns on the 1st Embodiment of this invention. It is a perspective view showing an outline of an example of a nondestructive inspection device concerning a 1st embodiment of the present invention. It is a figure which shows the imaging example of the X-ray transmission image of the tubular subject in the 1st Embodiment of this invention. It is a figure which shows the line profile of the example of a defect of the tubular specimen assumed in the 1st Embodiment of this invention. It is a flowchart which shows one procedure of the nondestructive inspection in the 1st Embodiment of this invention. It is a figure which shows the difference with the normal time of the digital data which show the radiation intensity distribution which permeate | transmitted the tube wall of the tubular subject in the 2nd Embodiment of this invention. It is the figure which plotted the determination parameter | index of the defect of the tubular test object in the 3rd Embodiment of this invention at intervals of fixed time. It is a figure which shows an example of a structure of the sensor in the 4th Embodiment of this invention. It is a figure which shows the example of the subtraction image of the nondestructive inspection apparatus which concerns on the 6th Embodiment of this invention. It is a figure which shows typically the principal part structure of another example of a structure of a sensor in the 7th Embodiment of this invention. The tubular subject in the seventh embodiment of the present invention is a color I.D. I. It is a figure which shows the example which image | photographed the X-ray transmission image using FIG. Color I.D in the seventh embodiment of the present invention. I. It is a figure which shows the example of evaluation of the tube wall thickness using. It is a figure which shows the concept of the nondestructive inspection using the correction | amendment material in the 8th embodiment of this invention. It is a block diagram which shows the concept of the application method of the stereo imaging | photography known as a three-dimensional photography method in the 9th Embodiment of this invention. It is an enlarged view of the measurement part in the measurement of the detection object part of the tube wall of the tubular subject using the application method of the stereo imaging | photography concerning the 9th Embodiment of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Nondestructive inspection apparatus 2, 2a, 2b, 2c, 2d ... Tubular object, 3, 3a, 3b ... Radiation source, 4 ... Sensor, 5 ... Data acquisition part, 6 ... Data processing part, 7 ... Display apparatus , 8 ... Sorting device, 9 ... Shielding body, 10 ... Tubular subject moving device, 11 ... Tray, 12, 16 ... Scintillator, 13 ... Shading cover, 14 ... Lens, 15, 20 ... Camera, 17 ... Photoelectric film, 18 DESCRIPTION OF SYMBOLS ... Electron lens, 19 ... Output fluorescent substance, 21 ... Correction member, 22 ... Contents, (alpha) 1, (alpha) 2 ... Radiation path, W ... Normal direction (width direction) of the surrounding surface of a tubular test object, L ... The tangential direction (depth direction) of the peripheral surface.

Claims (15)

A radiation source for irradiating the tubular subject from the side, and
An image sensor for obtaining a transmission image by detecting radiation transmitted through the tubular subject;
Tube wall information generating means for generating tube wall information of the tubular subject from the transmission image obtained by the image sensor;
An nondestructive inspection apparatus comprising: an evaluation unit that evaluates the soundness of the tubular subject based on the tube wall information generated by the tube wall information generation unit.   The evaluation unit evaluates the tube wall thickness of the tubular subject from the tube wall information generated by the tube wall information generation unit, and based on the tube wall thickness or the amount of change in the tube wall thickness, The nondestructive inspection apparatus according to claim 1, wherein the soundness of the tubular subject is evaluated.   The evaluation means takes the difference between the tube wall information generated by the tube wall information generation means and the tube wall information at normal time, and evaluates the soundness of the tubular subject from the difference data The nondestructive inspection apparatus according to claim 1.   The nondestructive inspection apparatus according to claim 2, wherein the evaluation unit evaluates the life of the tubular subject by time series analysis of the tube wall thickness obtained from the tube wall information.   The non-destructive inspection apparatus according to claim 3, wherein the evaluation means evaluates the life of the tubular subject by time series analysis of difference data between the tube wall information and the tube wall information in a normal state. .   6. The image sensor according to claim 1, wherein the image sensor includes a scintillator that reacts with radiation and emits light according to intensity, and a photodetector that converts the emitted light into an electrical signal. The non-destructive inspection device described in the section.   The image sensor reacts with radiation and emits light according to its intensity, means for converting the emitted light into an electrical signal, means for amplifying the electrical signal, and re-lighting the amplified electrical signal 6. The nondestructive inspection apparatus according to claim 1, wherein the non-destructive inspection apparatus comprises: an output phosphor that converts the light into a light source; and a camera that captures light emitted from the output phosphor. The radiation source irradiates the tubular subject with radiation from a plurality of different lateral directions;
The image sensor detects radiation transmitted through the tubular subject from the plurality of lateral directions to obtain a plurality of transmission images;
The tube wall information generating means generates tube wall information from enhanced image data in which the shape of the inner wall portion of the tubular subject obtained by taking the difference between the plurality of transmission images is enhanced,
6. The nondestructive inspection apparatus according to claim 1, wherein the evaluation unit evaluates the soundness of the tubular subject based on the tube wall information. The image sensor includes a scintillator that uses a phosphor that reacts with radiation and emits light with a broadband wavelength corresponding to the intensity thereof, and a color camera that captures light emitted from the phosphor.
By adjusting the light emission characteristics of the scintillator and the sensitivity characteristics of each component of the three primary colors of the camera light, the detection sensitivity to radiation is different for each component of the three primary colors of the camera light. The nondestructive inspection apparatus according to claim 6 or 7, wherein the measurement range is expanded by simultaneous measurement.   The nondestructive inspection apparatus according to claim 1, further comprising a correction member that has a concave portion corresponding to an outer peripheral surface of the tubular subject and suppresses halation. The radiation source irradiates the detection target part of the tubular subject from a plurality of predetermined lateral directions,
The image sensor detects radiation that passes through the detection target portions of the tubular subject from the plurality of predetermined side directions, and acquires a plurality of transmission images;
The tube wall information generation means, based on predetermined distance image data obtained by processing the plurality of transmission images, information on the detection target portion regarding the normal direction of the peripheral surface of the tubular subject, and Generating tube wall information having information on the detection target portion with respect to the tangential direction of the peripheral surface of the tubular subject;
The non-destructive inspection apparatus according to claim 1, wherein the evaluation unit evaluates the soundness of the detection target portion of the tubular subject based on the tube wall information. An irradiation step of irradiating the tubular subject with radiation from the side surface;
A transmission image acquisition step of obtaining a transmission image by detecting radiation transmitted through the tubular subject by irradiation of the radiation in the irradiation step with an image sensor;
A tube wall information generation step of generating tube wall information of the tubular subject from the transmission image obtained by the transmission image acquisition step;
A nondestructive inspection method comprising: an evaluation step of evaluating the soundness of the tubular subject based on the tube wall information generated by the tube wall information generation step. The evaluation step obtains difference data between the tube wall information generated by the tube wall information generation step and normal tube wall information, and evaluates the soundness of the tubular subject from the difference data. The nondestructive inspection method according to claim 12. The irradiation step irradiates the tubular subject with radiation from a plurality of different side directions,
The transmission image acquisition step detects radiation transmitted through the tubular subject from the plurality of side directions by an image sensor to acquire a plurality of transmission images,
The tube wall information generation step obtains enhanced image data in which the shape of the inner wall portion of the tubular subject is enhanced by taking a difference between the plurality of transmission images, and further generates tube wall information from the enhanced image data. And
The nondestructive inspection method according to claim 12 or 13, wherein the evaluation step determines the soundness of the tubular subject based on the tube wall information. The irradiation step irradiates the detection target portion of the tubular subject with radiation from a plurality of predetermined side directions,
The transmission image acquisition step detects radiation that passes through the detection target portions of the tubular subject from the plurality of predetermined side directions, and acquires a plurality of transmission images,
The tube wall information generation step processes the plurality of transmission images to obtain predetermined distance image data, and further, based on the predetermined distance image data, the normal direction of the peripheral surface of the tubular subject Generating tube wall information having information on the detection target portion and information on the detection target portion regarding the tangential direction of the peripheral surface of the tubular subject;
The nondestructive inspection method according to claim 12 or 13, wherein the evaluation step evaluates the soundness of the detection target portion of the tubular subject based on the tube wall information.