JP2022187538A - Nondestructive inspection system and nondestructive inspection method - Google Patents

Abstract

To provide a nondestructive inspection technique capable of enhancing both the ability to distinguish types of materials and their resolution.SOLUTION: A nondestructive inspection system 1 includes: an X-ray transmittance analysis unit 15 that analyzes the transmittance of X-ray R based on a difference between the intensity of X-ray R generated by an X-ray generator 4 and the intensity of X-ray R detected by an X-ray detector 5; a material area determination unit 16 that determines a material area 27 that is an area divided for each shape of an object 3 included in a target 2 based on the distribution of the transmittance; a muon passage coordinate analysis unit 17 that analyzes the passage coordinates and the passage angle of muon μ that has passed through each of muon trajectory detectors 6, 7; a muon trajectory data extraction unit 18 that extracts the trajectory of muon μ that has passed through the material area 27 based on the passage coordinates and the passage angle; and a muon scattering analysis unit 19 that analyzes a scattering angle θ of muon scattering that has occurred in the material area 27 based on the trajectory.SELECTED DRAWING: Figure 1

Description

Embodiments of the present invention relate to non-destructive inspection techniques.

Various inspections are performed in international distribution. For example, confirmation is made as to whether or not the items contained in the cargo to be transported are consistent with the contents of the application specification, or whether or not illegal substances are present. In particular, radiography using X-rays is widely used as a typical non-destructive inspection technique for inspecting the inside of transported goods such as containers without opening them. In this technique, an object (sample) to be measured is irradiated with X-rays, and a two-dimensional transmission image of the object to be measured is created based on the difference in X-ray transmittance that differs for each substance. Then, an inspector confirms the transmitted image to check the internal articles. In some cases, gamma-ray or neutron detectors are also used for the purpose of finding nuclear or radioactive material.

In recent years, as another inspection method, a cargo inspection method using cosmic ray muons has been developed. This method is called muon scattering method or muon tomography, and utilizes cosmic ray muons, which are natural high-energy particles falling from the sky. By detecting muon scattering that occurs in the substance through which the muons have passed, the distribution or type of substances in the cargo can be determined. This method was developed at Los Alamos National Laboratory in the United States in the 2000s for the purpose of detecting nuclear material such as uranium hidden in cargo.

The advantages of muon tomography are that unlike X-rays, it does not require an artificial radiation source and uses natural particles, so it is not bound by restrictions related to radiation exposure and safety. In addition, cosmic ray muons have a high energy of several GeV, and therefore have a high transmittance. Furthermore, it has a high ability to identify the type of material using the feature that the scattering angle of muons differs for each material.

Muon tomography has better performance than X-ray radiography in terms of material transmittance and ability to identify types of materials. A disadvantage of muon tomography, however, is that the accuracy of transmission images obtained is lower than that of X-ray radiography due to its low spatial resolution.

JP 2016-161485 A

The problem to be solved by the present invention is to provide a non-destructive inspection technique that can improve both the ability to identify the type of substance and the resolution.

A non-destructive inspection system according to an embodiment of the present invention includes an X-ray generator that generates X-rays to irradiate an object to be inspected, and an X-ray detector that detects the X-rays that have passed through the object. , an X-ray transmittance for analyzing the transmittance of the X-rays based on the difference between the intensity of the X-rays generated by the X-ray generator and the intensity of the X-rays detected by the X-ray detector; an analysis unit; a material region determination unit that determines a material region that is a region divided by shape of an object included in the object based on the distribution of the transmittance; At least one pair of muon trajectory detectors provided at positions facing each other across the muon trajectory detectors, a muon passing coordinate analysis unit for analyzing the passing coordinates and the passing angle of the muons passing through the respective muon trajectory detectors, and the passing coordinates and a muon trajectory data extraction unit that extracts the trajectory of the muon that has passed through the material region based on the passage angle, and a muon scattering that analyzes the scattering angle of muon scattering occurring in the material region based on the trajectory. An analysis unit, an output information generation unit that generates output information capable of identifying the type of substance existing in the substance region based on the scattering angle, and an output unit that outputs the output information.

Embodiments of the present invention provide non-destructive testing techniques that can increase both material type discrimination and resolution.

The block diagram which shows the nondestructive inspection system of 1st Embodiment. A block diagram showing a non-destructive inspection system. A flow chart showing a non-destructive inspection method. Explanatory drawing which shows the arrangement|positioning form of a sample. Explanatory drawing which shows the transmission image by X-ray. FIG. 4 is an explanatory diagram showing the result of determination of a material region by X-rays; Explanatory drawing which shows the transmission image by a muon. Explanatory drawing which shows an example of the flow of an output information generation process. Explanatory drawing which shows the measurement result of a sample. Explanatory drawing which shows the scattering angle of a muon. Graph showing the ratio of X-ray transmittance and muon scattering intensity. The block diagram which shows the X-ray measurement system of 2nd Embodiment. The block diagram which shows the muon measurement system of 2nd Embodiment.

(First embodiment)
Hereinafter, embodiments of a nondestructive inspection system and a nondestructive inspection method will be described in detail with reference to the drawings. First, a first embodiment will be described with reference to FIGS. 1 to 11. FIG.

Reference numeral 1 in FIG. 1 denotes the nondestructive inspection system of the first embodiment. This non-destructive inspection system 1 is for inspecting an object 2 without destroying it. For example, it is used to check whether a given object 3 is present in the object 2 . A vehicle such as a truck for transporting containers is exemplified as the object 2 to be inspected. Note that the object 2 may be a container that is transported by an aircraft or a ship, a luggage that can be carried manually, or the like.

The non-destructive inspection system 1 of the present embodiment inspects an object 2 using both radiography using X-rays (X-ray inspection) and muon tomography using muons (muon inspection). Then, the final determination result is obtained by integrating both test results. This non-destructive inspection system 1 has an image resolution equivalent to that of radiography and a substance identification capability similar to that of muon tomography.

The non-destructive inspection system 1 should be able to identify at least the type of substance. Further, the type of substance includes elements of the substance, composition of the substance, ratio of each element contained in the substance, density of the substance, amount of substance, and the like.

Muon inspection uses muon μ, which is a charged particle. Muon μ exists mainly as cosmic rays. The muon μ is a kind of secondary cosmic ray produced by reaction of the primary cosmic ray entering the earth from space with the earth's atmosphere. A muon μ has a positive or negative charge and a high energy of 3 to 4 GeV on average, so it has a high penetrating power. Muon μ can also be artificially generated using an accelerator. In this embodiment, a mode using muons μ of cosmic rays is exemplified, but artificially generated muons μ may be used.

The nondestructive inspection system 1 includes an X-ray generator 4 , an X-ray detector 5 , a first muon trajectory detector 6 , a second muon trajectory detector 7 and an analysis computer 8 .

The X-ray generator 4 is a device that generates X-rays R with which the object 2 is irradiated. The X-ray detector 5 is a device that detects X-rays R that have passed through the object 2 . In the first embodiment, the X-ray generator 4 and the X-ray detector 5 are provided at positions facing each other with the object 2 interposed therebetween. For example, they are provided at positions facing each other across the object 2 in the horizontal direction. The X-ray generator 4 irradiates the object 2 with X-rays R from the same direction with constant energy.

The first muon trajectory detector 6 and the second muon trajectory detector 7 are provided at positions facing each other with the object 2 interposed therebetween. For example, they are provided at positions facing each other with the object 2 sandwiched in the vertical direction. These pair of muon trajectory detectors 6 and 7 are devices for detecting muons μ, which are cosmic rays existing in nature.

The X-ray generator 4, X-ray detector 5, and muon trajectory detectors 6 and 7 are installed inside an examination room covered with a shielding member 9 such as thick concrete. Object 2 is placed inside an examination room. Since the X-rays R are shielded by the shielding member 9, it is possible to prevent personnel in the vicinity from being exposed to radiation. Since the muon μ has a higher transmittance than the X-ray R, it passes through the shielding member 9 .

In the first embodiment, the X-ray generator 4, the X-ray detector 5, and the pair of muon trajectory detectors 6 and 7 are installed at the same inspection location, and the X-ray inspection and the muon inspection are performed simultaneously. Illustrate how to do it. In other words, the X-ray inspection and the muon inspection are performed under the same conditions of inspection location and inspection time.

Next, the system configuration of the nondestructive inspection system 1 will be described with reference to the block diagram shown in FIG.

The X-ray generator 4 , the X-ray detector 5 and the muon trajectory detectors 6 and 7 are connected to an analysis computer 8 and controlled by the analysis computer 8 .

The analysis computer 8 includes an input section 10 , an output section 11 , a communication section 12 , a storage section 13 and a main control section 14 . The analysis computer 8 has hardware resources such as a CPU, ROM, RAM, and HDD, and the CPU executes various programs to realize information processing by software using the hardware resources. be done. Furthermore, the nondestructive inspection method of this embodiment is implemented by causing a computer to execute various programs.

Each component of the analysis computer 8 does not necessarily have to be provided in one computer. For example, one analyzing computer 8 may be realized using a plurality of computers connected to each other via a network. For example, a computer for controlling the X-ray generator 4 and the X-ray detector 5, a computer for controlling the muon trajectory detectors 6 and 7, and a computer for analyzing data may be separately provided.

Predetermined information is input to the input unit 10 according to the operation of the user who uses the analysis computer 8 . The input unit 10 includes an input device such as a mouse or keyboard. That is, predetermined information is input to the input unit 10 according to the operation of these input devices.

The output unit 11 outputs predetermined information. The analysis computer 8 includes a device for displaying images, such as a display for outputting analysis results. That is, the output unit 11 controls the image displayed on the display. The display may be separate from the computer main body, or may be integrated with the computer main body.

Note that the analysis computer 8 may control images displayed on a display of another computer connected via a network. In that case, the output unit 11 provided in another computer may control the output of the analysis result of this embodiment.

Note that in the present embodiment, a display is exemplified as a device for displaying images, but other modes may be used. For example, information may be displayed using a head-mounted display or a projector. Furthermore, a printer that prints information on a paper medium may be used as an alternative to the display. In other words, the target controlled by the output unit 11 may include a head mounted display, a projector, or a printer.

The communication unit 12 communicates with other computers via a communication line such as the Internet. In this embodiment, the computer for analysis 8 and another computer are connected to each other via the Internet, but other modes are also possible. For example, they may be connected to each other via a LAN (Local Area Network), a WAN (Wide Area Network), or a mobile communication network.

The storage unit 13 stores various kinds of information necessary for nondestructive inspection. For example, the storage unit 13 has a database that accumulates statistical values of scattering angles of muon scattering and substances corresponding to the respective statistical values. The database is a collection of information stored in memory, HDD, or cloud and organized so that it can be searched or stored.

The main control unit 14 controls the nondestructive inspection system 1 in an integrated manner. The main control unit 14 includes an X-ray transmittance analysis unit 15 , a material region determination unit 16 , a muon passage coordinate analysis unit 17 , a muon trajectory data extraction unit 18 , a muon scattering analysis unit 19 and an output information generation unit 20 . These are implemented by executing programs stored in the memory or HDD by the CPU. The output information generation unit 20 also includes a substance determination unit 21 and a transparent image generation unit 22 .

Next, a nondestructive inspection method executed using the nondestructive inspection system 1 will be described with reference to the flowchart of FIG. Note that the aforementioned block diagram (FIG. 2) will be referred to as appropriate. Furthermore, FIG. 4 to FIG. 11 will be referred to as appropriate.

Here, the images shown in FIGS. 5, 6, 7, and 9 are images created by the inventors by executing a Monte Carlo simulation. For example, as shown in FIG. 4, it is assumed that three types of blocks 24, 25, and 26 composed of different types of substances are arranged as predetermined samples in a predetermined space 23 on the simulation. Here, an iron block 24, a lead block 25 and a gold block 26 are arranged. The generation, transmission, and attenuation of X-rays are analyzed by simulation, and an X-ray transmission image (FIG. 5) is created from the analysis results. In addition, muon transmission and scattering are analyzed, and a muon transmission image (Fig. 7) is created from the analysis results.

As shown in FIG. 3, first, in step S1, the X-ray generator 4 generates X-rays R with which the object 2 to be inspected is irradiated.

In the next step S<b>2 , the X-ray detector 5 detects X-rays R that have passed through the object 2 . An X-ray transmission image (FIG. 5) is now obtained.

In the next step S3, the X-ray transmittance analysis unit 15, based on the difference between the intensity of the X-rays R generated by the X-ray generator 4 and the intensity of the X-rays R detected by the X-ray detector 5, , X-ray R transmittance.

In the next step S4, the material region determination unit 16 determines the material region, which is the region divided for each shape of the object 3 included in the object 2, based on the transmittance distribution analyzed by the X-ray transmittance analysis unit 15. Determine region 27 (FIG. 6).

Here, from the transmittance distribution analyzed by the X-ray transmittance analysis unit 15, the material region determination unit 16 defines a region in which the transmittance falls within a certain range as one material region 27. An X-ray transmission image of object 2 obtained by irradiation (FIG. 5) is divided into a plurality of material regions 27 (FIG. 6). By doing so, the shape of the object 3 formed for each transmittance can be represented in the transmission image.

For example, let the object 3 be an iron block 24, a lead block 25 and a gold block 26 (FIG. 4). Here, if the brightness of the portion with high X-ray R transmittance is decreased and the brightness of the portion with low X-ray R transmittance is increased, the X-ray transmission image shown in FIG. 5 is obtained. In this X-ray transmission image, the shape of each block 24, 25, 26 is clearly shown.

X-ray inspection using X-rays R has high image resolution, so the shape of the object 3 can be measured in detail. On the other hand, since the transmittance of the X-rays R is constant for the metal object 3 having a certain thickness or more, it is impossible to identify the type of substance that constitutes the object. Therefore, the X-ray examination is used not to determine the type of substance, but to determine the shape of the substance.

The material area determining unit 16 identifies areas in which the respective blocks 24, 25, and 26 are present, for example, by drawing a line identifying the material for each constant transmittance. For example, as shown in FIG. 6, an area where blocks 24, 25, and 26 are not installed and where air (space 23) exists, an area where iron block 24 exists, and a lead block 25 are arranged. It is assumed that there are four types of material regions 27, one in which gold blocks 26 exist and the other in which gold blocks 26 exist. Here, by drawing a line at the boundary of each material region 27, the shape of each block 24, 25, 26 appears. That is, the material region determination unit 16 can determine each material region 27 . However, X-ray inspection cannot determine what materials each of the four types of material regions 27 corresponds to. Therefore, muon inspection is used.

As shown in FIG. 3, steps S5 to S6 are performed in parallel with steps S1 to S4. First, in step S5, a pair of muon trajectory detectors 6 and 7 provided at positions facing each other with the object 2 interposed therebetween detects muons μ.

In the next step S6, the muon passage coordinate analysis unit 17 analyzes the passage coordinates and passage angle of the muon μ that has passed through the muon trajectory detectors 6 and 7, respectively.

Although not shown, each of the muon trajectory detectors 6 and 7 has a plurality of cylindrical drift tubes extending in the axial direction. Each drift tube is arranged two-dimensionally, and the drift tubes arranged two-dimensionally are further laminated to form one unit.

For example, each drift tube contains gas that is ionized by muons. When muons pass through the interior of the drift tube and ionize gas atoms to produce ions, the ions move to the core wire within the drift tube, causing a pulsed current to flow. This current allows the passage of muons to be detected. It should be noted that it is possible to detect at which position in the axial direction of the drift tube the ionization has occurred, by utilizing the property that the current flows in the shortest distance.

The first muon trajectory detector 6 and the second muon trajectory detector 7 are units having the same configuration. For example, as shown in FIG. 10, the description will be made assuming that the first muon trajectory detector 6 is on the muon μ incident side and the second muon trajectory detector 7 is on the muon μ emitting side. The second muon trajectory detector 7 may be on the muon μ incident side, and the first muon trajectory detector 6 may be on the muon μ emitting side.

The muon passage coordinate analysis unit 17 analyzes an incident vector 28 indicating passage coordinates and a passage angle of the muon μ at the time of incidence in the first muon trajectory detector 6 . Also, an emission vector 29 indicating the passage coordinates and the passage angle of the muon μ at the time of emission from the second muon trajectory detector 7 is analyzed.

As shown in FIG. 3, in step S7 following steps S4 and S6, the muon trajectory data extraction unit 18 extracts the material region 27 based on the passage coordinates and passage angle of the muon μ analyzed by the muon passage coordinate analysis unit 17. Extract the trajectory of the muon μ that passed through (FIG. 6).

Here, the muon trajectory data extraction unit 18 extracts the trajectory of the muon μ detected by the muon trajectory detectors 6 and 7 within a certain period of time (for example, within the range of 1 microsecond or less) by the same muon μ. Assume that the trajectory of the muon μ when it enters the object 2 (incident vector 28) and when it exits (exit vector 29) are treated as one data set (FIG. 10). This makes it easier to process the data necessary for the inspection using the muon μ.

For example, the incident vector 28 of the muon μ that has passed through the first muon trajectory detector 6 has six data of three-dimensional coordinates (Px, Py, Pz) and three-dimensional vectors (Vx, Vy, Vz). Similarly, the emission vector 29 of the muon μ that has passed through the second muon trajectory detector 7 also has six data. Here, the muon trajectory detectors 6 and 7 form a set of two units, and the muons μ detected simultaneously within a certain period of time are regarded as the same muon μ. Therefore, every time one muon μ is detected, the six data (Px1, Py1, Pz1, Vx1, Vy1, Vz1) detected by the first muon trajectory detector 6 and the data detected by the second muon trajectory detector 7 A total of 12 data sets of 6 data (Px2, Py2, Pz2, Vx2, Vy2, Vz2) are recorded. This dataset can be used to obtain the coordinates at which the muon μ was scattered.

The muon trajectory data extraction unit 18 also generates virtual straight lines 30 and 31 extending from the muon trajectory detectors 6 and 7 through which the muon μ passes, as trajectories, based on the passage coordinates and passage angle of the muon μ. By doing so, it becomes easier to perform the process of specifying the coordinates at which the muon scattering occurs.

For example, as shown in FIG. 10, the intersection of a virtual straight line 30 extending in the direction of the incident vector 28 and a virtual straight line 31 extending in the direction of the exit vector 29 is identified. This position indicates coordinates 32 where muon scattering occurred. The angle (difference between the trajectories) formed by the virtual straight lines 30 and 31 is the angle when the traveling direction of the muon μ changes, and is the scattering angle θ of the muon μ. The scattering angle θ is the magnitude of scattering of so-called muons μ.

As shown in FIG. 3, in the next step S8, the muon scattering analysis unit 19 analyzes the scattering angle θ of muon scattering generated in the material region 27 based on the trajectory of the muon μ. Here, the muon scattering analysis unit 19 takes the intersection of the virtual straight lines 30 and 31 as coordinates 32 where muon scattering occurs, and analyzes the scattering angle θ of the muon μ.

Further, the muon scattering analysis unit 19 accumulates and stores the results of scattering angles θ caused by a plurality of muons μ for each coordinate position. A statistical value of the accumulated results is analyzed as the scattering angle θ at the coordinates 32 where the scattering of the muon μ occurs. That is, the muon scattering analysis unit 19 analyzes the statistical value of the scattering angle θ of the muon scattering generated in the material region 27 based on the muon μ trajectory. In this way, quantitative analysis based on the statistical value of the scattering angle θ can be performed.

For example, when the muon trajectory data extraction unit 18 extracts the trajectories of a plurality of muons μ that have passed through one predetermined material region 27, the muon scattering analysis unit 19 extracts the muon When analyzing the scattering angle θ of μ, at least one statistic of the mean, median, variance, or arbitrary value of the scattering angle θ is calculated. By doing so, it is possible to improve the accuracy of the analysis based on the scattering angle θ. The arbitrary value is a value that can be arbitrarily set by the user. For example, a value of 60% of the scattering angle θ or a value of 80% of the scattering angle θ may be used as the statistical value. Data indicating the statistical values of the scattering angles θ and the types of substances corresponding to the respective statistical values are stored in advance in the database of the storage unit 13 .

In the next step S9, the output information generating section 20 executes processing for generating output information. This generation processing is to generate output information capable of identifying the type of substance present in the substance region 27 based on the scattering angle θ.

For example, the substance determination unit 21 of the output information generation unit 20 determines the type of substance existing in the substance region 27 . In this case, the output information is information indicating the determination result of the substance type. In this way, the type of substance can be determined automatically. The determination result may be shown in sentences or may be shown in a predetermined graph. Furthermore, a predetermined warning may be output. For example, if the type of material is nuclear material such as uranium or dangerous material such as explosives, a predetermined warning may be output.

Further, the substance determination unit 21 of the output information generation unit 20 refers to the database of the storage unit 13, specifies a substance preset corresponding to the statistical value, and determines the type of substance existing in the substance region 27. . By doing so, the accuracy of automatically determining the type of substance is improved.

Further, the transmission image generation section 22 of the output information generation section 20 generates a transmission image (FIG. 9) of the object 2. FIG. In this case, the output information is a transmission image of the object 2 . In this way, the user can determine the type of substance based on the transmission image of the object 2 . Furthermore, since the shape of the object 3 included in the object 2 is clearly shown in the transparent image of the object 2, the user can easily recognize what the object 3 is.

For example, as shown in FIG. 7, the muon transmission image acquired by the muon inspection has lower image resolution (spatial resolution) than the X-ray transmission image (FIG. 5). Therefore, an image in which the outlines of the shapes of the respective blocks 24, 25, and 26 are blurred is obtained. On the other hand, in muon scattering, the scattering angle θ changes according to the type of substance. Therefore, it is possible to more clearly acquire the difference for each material compared to the case of identifying the material using the X-ray transmittance.

The scattering angle θ ₀ of muon scattering is shown in Equation 1 below. Here, the scattering angle θ ₀ varies depending on the radiation length X ₀ inherent in the atomic number of the material. Note that p is the momentum of the muon. βc is the muon velocity. z is the charge of the muon. x is the distance a muon travels through a substance.

Since the radial length X ₀ varies with material, the analyzed scattering angle θ can be used to deduce the material present at coordinates 32 where the scattering occurred.

Also, the relationship between the magnitude of muon scattering and the type of substance is as shown in Equation 1. By using this Equation ₁ and calculating the value of X0 for the type of substance from the size of the scattering angle θ, the substance existing in the substance region 27 can be estimated.

Here, the difference in substance identification performance between X-ray and muon scattering is compared. FIG. 11 is a graph showing the ratio of X-ray transmittance and muon scattering intensity. This graph shows the ratio between the X-ray transmittance and the muon scattering intensity for lead and gold, with iron as the reference.

There is almost no difference in X-ray transmittance between lead and gold when iron is used as a reference. In contrast, muon scattering is 1.5 times higher for lead than iron and 1.7 times higher for gold than iron. In other words, it has been shown that the use of muon scattering produces a clearer difference for each material than the use of X-ray transmittance, enabling identification of the material.

FIG. 8 shows an example of the flow of output information generation processing. This example shows a procedure for extracting the muon scattering angle θ with respect to the material region 27 .

For example, an X-ray transmission image 33 obtained by X-ray inspection and a muon transmission image 34 obtained by muon inspection are used. First, each material region 27 is determined based on the X-ray transmission image 33, and the material region 27 whose type of material is to be determined is set.

Next, from the muon transmission image 34, only the muon scattering corresponding to the set material region 27 is specified, the scattering angle θ of the muon scattering is extracted, and the extraction result 35 is obtained. Statistical values of the extracted scattering angles .theta. are calculated to obtain measurement results 36 of the scattering angles .theta. By executing this procedure, the muon scattering angle θ of the material region 27 can be analyzed while maintaining image resolution equivalent to that of X-ray inspection.

In the measurement result 36 obtained by this extraction procedure, the brightness of the material region 27 is averaged based on the statistical value of the scattering angle θ. For example, as shown in FIG. 9, transmission images of blocks 24, 25, and 26 (object 2) that are color-coded according to the type of material present in material region 27 can be generated. That is, the transmission image of the object 2 is displayed in a different manner for each type of substance present in the substance region 27 . The user can determine the type of material based on the difference in lightness of the transmitted image. Furthermore, the substance determination unit 21 may automatically perform the determination.

In the conventional muon scattering analysis, since the average value of the muon scattering angle is calculated for each pixel of the transmission image obtained by the muon inspection, the statistical error becomes large when the statistic is small. be. On the other hand, in this embodiment, the average value of the muon scattering angles of the entire material region specified using X-rays is used, so statistical errors can be reduced.

As shown in FIG. 3, in the next step S10, the output unit 11 outputs information for output. Then, the nondestructive inspection method ends. The above steps are at least part of the nondestructive inspection method, and other steps may be included in the nondestructive inspection method.

In addition, in the flowchart of the present embodiment, each step is exemplified in a form in which each step is executed in series. good. Also, some steps may be executed in parallel with other steps.

In addition, in the first embodiment, the X-ray generator 4 irradiates the object 2 with the X-rays R at a constant energy, but other aspects may be adopted. For example, the energy of the X-rays R with which the X-ray generator 4 irradiates the object 2 may be changed every certain period.

For example, as shown in FIG. 1, when the X-ray generator 4 irradiates the object 2 with X-rays R from the same direction, the X-rays R are emitted with the energy changed at regular intervals. do. Furthermore, an X-ray transmission image (FIG. 5) is acquired for each energy.

As shown in FIG. 2, the material region determination unit 16 determines the material region 27 (FIG. 6) based on the transmittance of the X-rays R, which differs for each energy. In this way, each material region 27 can be divided in detail. For example, iron and lead have different transmittances for different energies. Therefore, by obtaining several patterns of X-ray transmission images with different energies and referring to these X-ray transmission images, it becomes easier to divide the material regions 27 for each material contained in the object 2 . In this manner, the type of material can be identified to some extent at the stage of the X-ray inspection, and the determination of the material region 27 can be performed with higher accuracy.

In the first embodiment, the X-ray inspection and the muon inspection are performed under the same conditions in terms of inspection location and inspection time, but other modes may be used. For example, when the same inspection location is used for X-ray inspection and muon inspection, the date and time for X-ray inspection and the date and time for muon inspection may be different.

(Second embodiment)
Next, a second embodiment will be described with reference to FIGS. 12 and 13. FIG. The same reference numerals are assigned to the same components as those shown in the above-described embodiment, and overlapping descriptions are omitted.

As shown in FIG. 12, the nondestructive inspection system 1A of the second embodiment includes a first X-ray generator 4A, a first X-ray detector 5A, and a second X-ray generator 4B provided at a predetermined first inspection location. and a second X-ray detector 5B. Note that the first inspection location is provided in an inspection room covered with the shielding member 9 . Furthermore, as shown in FIG. 13, the non-destructive inspection system 1A comprises a pair of muon trajectory detectors 6, 7 provided at a second inspection location different from the first inspection location.

The first inspection location and the second inspection location are described as being adjacent to each other. Note that in the second embodiment, one analysis computer 8 is used to control the devices at the first inspection location and the second inspection location. Separate analysis computers 8 may be installed at the first inspection location and the second inspection location, respectively, and the analysis computers 8 may be connected to each other via a communication line.

In the second embodiment, the X-ray inspection using the X-ray generator 4 and the X-ray detector 5 and the muon inspection using the muon trajectory detectors 6 and 7 are performed under different inspection locations and inspection times. . That is, the X-ray inspection and the muon inspection are performed separately.

For example, assume that there are a plurality of trucks as the plurality of objects 2 . Here, the following truck is muon inspected at the second inspection location while the preceding truck is being X-ray inspected at the first inspection location. That is, the following track performs muon inspection using the waiting time of the X-ray inspection of the previous track.

In the X-ray examination, it is necessary to shield with the shielding member 9 . For example, when the truck is housed in an inspection room covered with the shielding member 9, opening and closing time of the shielding door and loading time are required. Furthermore, after the X-ray inspection is finished, it takes time to open and close the shielding door again and carry out the product. In this way, when X-ray inspection is continuously performed by a plurality of trucks, the subsequent trucks need to wait at a predetermined standby location until the X-ray inspection of the preceding truck is completed.

On the other hand, in the muon inspection, it is not necessary to shield with the shielding member 9 . In addition, since cosmic rays are used, there is no need for equipment that generates muons. A second inspection location can be provided simply by installing a set of muon trajectory detectors 6 and 7 at a predetermined standby location.

In this way, the subsequent truck can be inspected for muons by utilizing the time the preceding truck is placed in the inspection chamber covered with the shielding member 9 and the time taken out. Therefore, two types of inspection can be efficiently performed.

Further, in the second embodiment, the first X-ray generator 4A and the first X-ray detector 5A are provided at positions facing each other with the object 2 interposed therebetween. Here, the X-rays R emitted from the first X-ray generator 4A are detected by the first X-ray detector 5A.

Further, a second X-ray generator 4B and a second X-ray detector 5B are provided at positions facing each other with the object 2 interposed therebetween. Here, the X-rays R emitted from the second X-ray generator 4B are detected by the second X-ray detector 5B.

In the second embodiment, the first X-ray generator 4A and the second X-ray generator 4B irradiate the object 2 with X-rays R from a plurality of different directions. In the example of FIG. 13, X-rays R from the first X-ray generator 4A are emitted from behind (horizontally) the track as the object 2, and X-rays R from the second X-ray generator 4B are emitted from above (vertically) the track. X-ray R is irradiated. That is, the irradiation directions of the two X-rays R cross each other at right angles. The first X-ray detector 5A and the second X-ray detector 5B detect the X-rays R that have passed through the object 2 from a plurality of different directions. By doing so, it is possible to improve the accuracy of the X-ray transmission image.

For example, by irradiating the object 2 with X-rays R in a plurality of horizontal and vertical directions, a plurality of X-ray transmission images are acquired, and by referring to these X-ray transmission images, the Three-dimensional information can be obtained. Also, in the muon inspection, three-dimensional information of the object 2 can be acquired in one inspection. By combining the two, it is possible to obtain information indicating the three-dimensional distribution of substances.

Note that when an X-ray transmission image (two-dimensional data) is obtained by X-ray examination, the material region 27 is a range having a predetermined area. Further, when an X-ray volume image (three-dimensional data) is obtained by X-ray examination, the material region 27 is a range having a predetermined volume.

In addition, the nondestructive inspection system 1A of the second embodiment includes the reference portion 37 provided at a position that is relatively fixed with respect to the object 2 and that is commonly used in the X-ray inspection and the muon inspection. Prepare. Furthermore, the muon trajectory data extraction unit 18 (FIG. 2) of the analysis computer 8 extracts the coordinates of the object 2 during the X-ray inspection and the coordinates of the object 2 during the muon inspection based on the coordinates of the reference unit 37. to correct. By doing so, it is possible to correct the positional deviation of the object 2 caused by the X-ray inspection and the muon inspection.

For example, when an X-ray inspection and a muon inspection are performed at different inspection locations, it is necessary to match the coordinates of the acquired X-ray transmission image and the muon transmission image. Therefore, a reference portion 37 (coordinate identification sample) is provided as a coordinate reference. A member of known material such as a block of lead is used for the reference portion 37 . A member whose material is known includes the meaning of a member whose at least one of the X-ray transmittance and the muon scattering angle is known.

Also, when the object 2 is a truck, a base 38 on which the truck is placed is provided with a reference portion 37 . Note that the reference portion 37 may be fixed to the body of the truck.

Since the position (coordinates) of the reference portion 37 is provided at a position (coordinates) that is relatively fixed with respect to the object 2, the respective coordinates of the transmission images acquired by both the X-ray inspection and the muon inspection can be matched using the reference portion 37 as a reference.

Note that the reference portion 37 used in the X-ray inspection and the muon inspection may be of the same shape, size and material. In other words, a plurality of reference portions 37 different as members (objects) may be used for each of the X-ray inspection and the muon inspection.

In the second embodiment, the X-ray inspection and the muon inspection are performed under different conditions in terms of both the inspection location and the inspection time. For example, the X-ray inspection and the muon inspection may be performed at the same inspection location, and the date and time of the X-ray inspection and the date and time of the muon inspection may be different. In this case, in order to match the coordinates of the acquired X-ray transmission image and the muon transmission image, a reference unit 37 may be provided as a coordinate reference.

The nondestructive inspection system and nondestructive inspection method have been described based on the first and second embodiments, but the configuration applied in any one embodiment may be applied to other embodiments, You may combine the structure applied in each embodiment.

The system of the above-described embodiment includes a control device in which a processor such as a dedicated chip, FPGA (Field Programmable Gate Array), GPU (Graphics Processing Unit), or CPU (Central Processing Unit) is highly integrated, and a ROM (Read Only Memory) or RAM (Random Access Memory), external storage devices such as HDD (Hard Disk Drive) or SSD (Solid State Drive), display devices such as displays, and input devices such as mice or keyboards and a communication interface. This system can be realized with a hardware configuration using a normal computer.

It should be noted that the program executed by the system of the above-described embodiment is pre-installed in a ROM or the like and provided. Alternatively, this program can be stored as an installable or executable file on a non-transitory computer-readable storage medium such as CD-ROM, CD-R, memory card, DVD, flexible disk (FD), etc. may be stored and provided.

Also, the program executed by this system may be stored on a computer connected to a network such as the Internet, downloaded via the network, and provided. In addition, this system can also be configured by combining separate modules that independently perform each function of the constituent elements and are interconnected by a network or a dedicated line.

In the above-described embodiment, a pair of muon trajectory detectors 6 and 7 are provided at positions facing each other with the object 2 interposed therebetween in the vertical direction. For example, two sets of muon trajectory detectors 6 and 7 may be provided at positions facing each other across the object 2 in the vertical and horizontal directions. Also, two muon trajectory detectors do not have to be one set, and an odd number of muon trajectory detectors may be provided. For example, more than two muon trajectory detectors may be provided.

According to at least one embodiment described above, by providing an output information generation unit that generates output information capable of identifying the type of substance present in the substance region based on the scattering angle, the type of substance can be identified. Both power and resolution can be increased.

While several embodiments of the invention have been described, these embodiments have been presented by way of example and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, replacements, changes, and combinations can be made without departing from the scope of the invention. These embodiments and their modifications are included in the scope and spirit of the invention, as well as the invention described in the claims and equivalents thereof.

DESCRIPTION OF SYMBOLS 1 (1A)... Non-destructive inspection system, 2... Object, 3... Object, 4 (4A, 4B)... X-ray generator, 5 (5A, 5B)... X-ray detector, 6... First muon trajectory detection Device 7 Second muon trajectory detector 8 Computer for analysis 9 Shielding member 10 Input unit 11 Output unit 12 Communication unit 13 Storage unit 14 Main control unit 15 X-ray transmittance analysis unit 16 substance region determination unit 17 muon passage coordinate analysis unit 18 muon trajectory data extraction unit 19 muon scattering analysis unit 20 output information generation unit 21 substance determination unit 22... Transmission image generator 23... Space 24... Iron block 25... Lead block 26... Gold block 27... Substance area 28... Incident vector 29... Exit vector 30, 31... Virtual Straight line 32 Coordinates 33 X-ray transmission image 34 Muon transmission image 35 Extraction result 36 Measurement result 37 Reference part 38 Pedestal R X-ray θ Scattering angle μ Muon.

Claims (13)

an X-ray generator that generates X-rays to irradiate an object to be inspected;
an X-ray detector that detects the X-rays that have passed through the object;
X-ray transmittance analysis for analyzing the transmittance of the X-rays based on the difference between the intensity of the X-rays generated by the X-ray generator and the intensity of the X-rays detected by the X-ray detector Department and
a material area determination unit that determines a material area, which is an area divided by shape of an object included in the target object, based on the transmittance distribution;
at least one pair of muon trajectory detectors that detect muons and are provided at positions facing each other across the object;
a muon passing coordinate analysis unit that analyzes the passing coordinates and passing angles of the muons that have passed through each of the muon trajectory detectors;
a muon trajectory data extraction unit that extracts the trajectory of the muon that has passed through the material region based on the passage coordinates and the passage angle;
a muon scattering analysis unit that analyzes the scattering angle of muon scattering occurring in the material region based on the trajectory;
an output information generating unit that generates output information capable of identifying the type of material present in the material region based on the scattering angle;
an output unit that outputs the information for output;
comprising
Nondestructive inspection system. The output information generation unit includes a substance determination unit that determines the type of the substance present in the substance region,
At least one of the output information is information indicating the determination result of the type of the substance,
The non-destructive inspection system according to claim 1. The output information generation unit includes a transmission image generation unit that generates a transmission image of the object,
at least one of the output information is a transmission image of the object;
The nondestructive inspection system according to claim 1 or 2. The material region determination unit
From the distribution of the transmittance analyzed by the X-ray transmittance analysis unit, a region in which the transmittance falls within a certain range of values is defined as one material region,
dividing the transmission image of the object obtained by the X-ray irradiation into a plurality of the material regions;
The nondestructive inspection system according to any one of claims 1 to 3. The muon trajectory data extraction unit
Assume that the trajectories of the muons detected within a certain period of time by each of the muon trajectory detectors are due to the same muon;
Treating the trajectory when the muon is incident on the object and the trajectory when the muon is emitted from the object as one data set;
The nondestructive inspection system according to any one of claims 1 to 4. The muon trajectory data extraction unit generates, as the trajectory, a virtual straight line extending from each of the muon trajectory detectors through which the muon has passed, based on the passage coordinates and the passage angle of the muon,
The muon scattering analysis unit uses the intersection of the straight lines as coordinates at which the muon scattering occurs, and analyzes the scattering angle.
The nondestructive inspection system according to any one of claims 1 to 5. An X-ray inspection using the X-ray generator and the X-ray detector and a muon inspection using the muon trajectory detector are performed under different conditions in at least one of an inspection location and an inspection time,
a reference part provided at a position that is relatively fixed with respect to the object and is commonly used in the X-ray inspection and the muon inspection;
The muon trajectory data extraction unit corrects the coordinates of the object during the X-ray inspection and the coordinates of the object during the muon inspection based on the coordinates of the reference unit.
The nondestructive inspection system according to any one of claims 1 to 6. The X-ray generator irradiates the object with the X-rays from a plurality of different directions,
The X-ray detector detects the X-rays that have passed through the object from a plurality of different directions.
The nondestructive inspection system according to any one of claims 1 to 7. The X-ray generator irradiates the object with the X-rays having different energies,
wherein the material region determining unit determines the material region based on the transmittance of the X-ray that differs for each energy;
The nondestructive inspection system according to any one of claims 1 to 8. The muon scattering analysis unit analyzes statistical values of the scattering angle of the muon scattering occurring in the material region based on the trajectory.
The nondestructive inspection system according to any one of claims 1 to 9. The muon trajectory data extraction unit extracts the trajectories of the plurality of muons that have passed through one of the material regions,
When analyzing the scattering angle of each of the muons from the trajectories of the plurality of muons, the muon scattering analysis unit is configured to select at least an average value, a median value, a variance, or an arbitrary value of the scattering angles. calculating one said statistic;
The non-destructive inspection system according to claim 10. The output information generation unit includes a substance determination unit that identifies the substance preset corresponding to the statistical value and determines the type of the substance present in the substance region.
The nondestructive inspection system according to claim 10 or 11. an X-ray generator generating X-rays to irradiate an object to be inspected;
an X-ray detector detecting the X-rays transmitted through the object;
The X-ray transmittance analysis unit determines the transmittance of the X-ray based on the difference between the intensity of the X-ray generated by the X-ray generator and the intensity of the X-ray detected by the X-ray detector. and parsing
a step of determining a material region, which is a region divided by shape of an object included in the target object, based on the transmittance distribution;
a step of detecting muons by at least one pair of muon trajectory detectors provided at positions facing each other with the object sandwiched therebetween;
a step in which a muon passage coordinate analysis unit analyzes passage coordinates and passage angles of the muons that have passed through each of the muon trajectory detectors;
a step in which a muon trajectory data extraction unit extracts the trajectory of the muon that has passed through the material region based on the passage coordinates and the passage angle;
a muon scattering analysis unit analyzing a scattering angle of muon scattering occurring in the material region based on the trajectory;
an output information generating unit generating output information capable of identifying the type of material existing in the material region based on the scattering angle;
an output unit outputting the information for output;
including,
Non-destructive inspection method.

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