JPH11194102A - Method and apparatus for discrimination of substance at inside of vessel and burning method for low-radioactivity waste - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and an apparatus in which whether a metal substance (a nonburning substance) exists so as to be mixed with a substance inside a carton box can be confirmed easily and in which whether a carton box used to seal up a low-radioactivity waste is to be burned or not is judged quickly and surely. SOLUTION: In a method and an apparatus, a plurality of X-ray fluoroscopic images are formed regarding an identical object by projection X-rays in different directions from an X-ray generator 5, a histogram is formed on the basis of the images, it is compared with a threshold value which is stored in advance, and the existence of a metal substance (a nonburning substance) 3 is discriminated. In addition, whether the low-radioactivity waste is to be bruned or not is judged.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for identifying metallic substances in a container, and a method for burning low radioactive waste.

[0002]

2. Description of the Related Art In some cases, it is desired to check the presence of a metal substance in a carton box (for example, a container such as a plastic container or a cardboard) without opening. Particularly, in the case of a container or the like in which low-radiation waste is sealed, when a carton box is incinerated to reduce its volume, the presence of a metal substance makes the subsequent processing troublesome, and this is even more so. In such a case, the presence of a metal has conventionally been identified by a metal detector.

The present inventors have proposed in Japanese Patent Application No. 9-40333 a method of determining the volume and weight of a substance from an X-ray fluoroscopic image by limiting the investigation target to a specific kind of substance. In this method, a minute volume is obtained by setting a surface area for each pixel of an X-ray fluoroscopic image, and a density value thereof is set as a depth, and the entire volume is obtained by integrating the minute volume.

[0004]

It has been practiced to use a metal detector in an unopened state to determine whether or not a metal exists in a substance in a carton box. However, a threshold value indicating whether or not the substance is a metal has been used. Because of the difficulty in setting, even if there is an audio warning by an alarm, it was not possible to determine (confirm) whether metal actually exists.

[0005] When low radioactive waste is stored in a carton box, it is not only difficult for a metal detector to determine whether non-combustible materials are present, but also to remove it from the combustion process. It was difficult to judge whether or not it was coming.

[0006] In view of such circumstances, the present invention makes it possible to easily confirm whether or not a substance, for example, a metallic substance, or a non-combustible substance is not mixed in the substance in the carton box. It is an object of the present invention to provide a method and an apparatus which can make an erroneous determination as possible.

Further, according to the present invention, when the substance in the carton box is a low-radioactive substance, it is easily determined whether or not non-combustible substances such as metallic substances are mixed, and the volume reduction due to the combustion of the carton box is reduced. It is an object of the present invention to provide a low-radioactive waste combustion method that can be performed as designed.

[0008]

SUMMARY OF THE INVENTION The present invention seeks to confirm the presence or absence of a substance in a container, for example, a metal substance, from the grayscale value data of an X-ray fluoroscopic image.
It is intended to confirm the presence or absence of a metal substance in the container from a histogram of the gray value data of the fluoroscopic image. That is, one of the features is that the gray value data of the X-ray fluoroscopic images of the same object from different directions are combined and the presence or absence of the corresponding substance in the container is confirmed.

Another feature of the present invention is to determine whether a carton box enclosing low radioactive waste is to be excluded from the combustion process by identifying non-combustible substances from the composite data of gray value data. is there.

The present invention specifically provides the following method and apparatus.

According to the present invention, there is provided a method for identifying a substance in a container, for example, a metal substance, by X-ray projection, wherein a plurality of objects of the same object are simultaneously irradiated by X-rays projected in different directions from an X-ray generator. Of the X-ray fluoroscopy images, forming respective histograms from the gray values of these X-ray fluoroscopic images, forming a composite histogram from these histograms, and storing a pre-stored value for metallic materials or non-combustible materials. A method for identifying a substance in a container, characterized in that the presence of the substance is identified by comparing with a threshold value on a histogram.

According to the present invention, there is provided an apparatus for identifying a substance in a container, for example, a metallic substance, by X-ray projection, comprising: an X-ray projector comprising an X-ray generator and an X-ray detector; Means for forming a plurality of X-ray fluoroscopic images of the same object by projection X-rays having different projection energies from a ray generator, forming respective histograms from these X-ray fluoroscopic images, and combining these histograms Means for forming a histogram, means for storing threshold values on histograms stored in advance for various substances, and transfer of the threshold values to compare with the composite histogram to determine the presence of the substance. And a device for identifying a substance in a container.

[0013] The present invention relates to a method for incinerating a carton box in which low radioactive waste is sealed, wherein the non-combustible substance in the carton box is identified by combining the gray value data of the fluoroscopic image. A method for burning low radioactive waste, characterized in that said carton box is excluded from the combustion process when material is identified.

According to the present invention, there is provided a method for incinerating a carton box in which low radioactive waste is sealed, wherein an X-ray from an X-ray generator is projected on the carton box to form an X-ray fluoroscopic image. Identify non-combustible substances such as metallic substances from the fluoroscopic image, and determine the surface area of each pixel of the X-ray fluoroscopic image, determine the minute volume with the depth as its depth, determine the total volume by integrating it, A method for burning low radioactive waste, characterized in that the carton box is excluded from the combustion process when the volume of the non-combustible substance is greater than or equal to a threshold value.

In the present invention, an easy-to-use material such as a retort pack for parcels and foods, which is relatively easy to transmit X-rays, is also called a carton box.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment according to the present invention will be described below with reference to the drawings.

FIG. 1 shows a schematic configuration of an embodiment of the present invention. In the figure, a carton box 1 in which low radioactive waste is sealed is carried by a belt conveyor 2 in a traveling direction indicated by an arrow. Metallic substances or non-combustible substances 3 may be mixed in the carton box 1. Less than,
The case where a metal substance is mixed will be described as an example. An X-ray protection room 4 is provided at a position where the belt conveyor 2 is located. In this room, an X-ray generator 5 and an X-ray line sensor 6 are arranged along the belt conveyor 2 and opposed to both sides thereof. Is done. Therefore, the substance existing inside the carton box 1 is extracted as an image signal by the X-ray line sensor 6 by the X-rays projected from the X-ray generator 5.

A plurality of X-ray line sensors 6 are provided along the belt conveyor 2. For example, three are installed as shown in the figure. At that time, in order to minimize the hardware configuration, one X-ray generator and three X-ray line sensors are used in a set. In this way, by simultaneously using the X-ray irradiation angle of the X-ray generator 5 to obtain an X-ray fluoroscopic image, for example, 3
Three line sensors are installed within 0 degree. In this manner, a plurality of X-ray fluoroscopic images (signals) of the same object, that is, the substance of the carton box 1 can be simultaneously formed by the X-rays projected from the X-ray generator 5 having different projection directions. It suffices if projection X-rays having different projection directions are projected onto the same object, and a plurality of X-ray generators may be used.

As described above, in each X-ray line sensor 6, scanning is performed in accordance with the movement of the carton box 1 to obtain an X-ray fluoroscopic image signal. These X-ray fluoroscopic image signals are AD-converted by the AD converter 7 and stored in the image memory 8 for each pixel. The CPU 9 performs processing based on pixel information from the image memory 8. For example, the gray value is counted for the pixels stored in the image memory 8. At the stage when the carton box 1 has passed, a count for each image gray level value, that is, a histogram is formed for each image. The histograms are used alone or in combination in a combined manner to calculate the presence / absence of a metal substance in the carton box 1. At this time, a certain threshold value is used for the histogram, and the threshold value is previously converted into data as a tendency of the histogram of various metals and nonmetals, that is, a threshold value on the histogram,
It is memorized.

If the target is limited to a specific type of substance,
The fact that the volume and weight can be obtained from the X-ray fluoroscopic image is as follows.
The present inventors have shown in Japanese Patent Application No. 9-40333. this is,
The surface area is defined for each pixel of the X-ray fluoroscopic image, the minute volume is determined using the density value as the depth, and the total volume is determined by integrating the minute volume. In this case, since the target substance is a known kind, there is a relationship between the gray value and the depth in advance, which can be realized.

Also in the case of the present embodiment, the volume of the target object can be obtained by the same concept. Japanese Patent Application 9-40
If the method of 333 is used, even if the photographing directions are different, the volume is the same if the object is the same.

When a metal and a non-metal are contained in the same carton box and have the same density value and the same surface area when viewed through X-rays from a certain direction (direction A), for example, 1
When X-ray fluoroscopy is performed from an oblique direction of 5 degrees (B direction) or 30 degrees (C direction), the above-mentioned metal and non-metal should have different perspectives in terms of density and surface area. this is,
Even if the same surface area can be seen through X-rays from the A direction, the distance between metal and non-metal in the X-ray transmission direction (depth)
Are different, that is, the original volumes are different.
However, there is a contradiction to the above-mentioned "When the method of Japanese Patent Application No. 9-40333 is used, even if the photographing directions are different, the volume is the same if the object is the same". This is because the above-mentioned condition "if the target is limited to a specific type of substance" is ignored.

That is, the volume of a substance obtained by using a relationship between a certain gray value and depth is the same regardless of the X-ray imaging direction. If this is not the case, the relationship between the gray value and the depth is incorrect. That is, the substance is different from the substance considered as the target.

Therefore, if the relationship between the gray value and the depth of all the typical substances of metals and non-metals or the assumed substances is determined, the classification of metals and non-metals and the possible Identification becomes possible.

Next, a method based on a histogram for classifying metals and non-metals without obtaining a volume will be described with reference to FIG.

As described above, each X-ray line sensor 6 scans in accordance with the movement of the carton box to obtain an X-ray fluoroscopic image 21 and counts the density of the image based on the pixels of this image. , Histogram 22
To form The histogram 23 is added to form a composite histogram 24. On the monitor 10 shown in FIG. 1, a composite histogram is displayed according to the shade. That is, the histogram 25 of the measured substance and the histogram 26 as the background are displayed on the screen.

A gray level value is obtained for a typical metal or non-metallic substance or an assumed substance and stored. The gray value data is used as threshold values 27 and 28 on the histogram.
Will be displayed on the screen. Therefore, it becomes possible to compare the histogram 25 of the measured substance with the thresholds 27 and 28 or specify the substance 29 measured by a specific relationship.

Referring to FIG. 1, a description will be given of a case where the volume is reduced by employing the low-radioactive waste combustion method. As described above, the low radioactive substance is sealed in the carton box 1. This carton box 1 by CPU9
It is discriminated whether or not the metal substance 3 is not mixed therein. When a non-combustible substance such as a metal substance is identified, the determination processing device 11 determines whether or not to exclude the carton box 1 from the combustion process. In this case, X
A low-radioactive waste combustion method for identifying non-combustible substances in the carton box 1 by combining the gray value data of the fluoroscopic image and excluding the carton box 1 from the combustion process when the non-combustible substances are identified. Adopted. Alternatively, X-rays from the X-ray generator 5 are projected onto the carton box 1 to form an X-ray fluoroscopic image, and each pixel of the X-ray fluoroscopic image is defined as a surface area,
A low volume of radioactive waste is obtained by calculating a minute volume using the density as a depth, integrating the volume, and obtaining the entire volume, and excluding the carton box 1 from the combustion process when the volume of non-combustible substances is equal to or greater than a threshold value. A combustion method is employed.

[0029]

According to the present invention, a fluoroscopic image is displayed using X-rays so that an operator can visually determine the presence of a relevant substance, for example, a metallic substance or a non-combustible substance from gray-scale value data. can do.

According to the present invention, it is possible to very easily and reliably determine whether to incinerate a carton box in which low radioactive waste is sealed. As a result, the volume of the low radioactive material can be reliably reduced.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an embodiment of the present invention.

FIG. 2 is a partially detailed explanatory view of FIG. 1;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Carton box, 2 ... Conveyer belt, 3 ... Metal substance (non-combustible substance), 5 ... X-ray generator, 6 ... X-ray line sensor, 7 ... AD converter, 8 ... Image memory, 9 ... CP
U, 10 monitor, 11 judgment processing device.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI G01N 23/18 G21F 9/32 Z G21F 9/32 B09B 5/00 T

Claims (4)

[Claims] 1. The method according to claim 1, wherein the metallic substance or the non-combustible substance in the container is X
In the method for identifying a substance in a container by X-ray projection, a plurality of X-ray fluoroscopic images of the same object are simultaneously formed by X-rays projected in different directions from an X-ray generator, and the gray scale values of these X-ray fluoroscopic images are formed. By forming respective histograms from these histograms, forming a composite histogram from these histograms, and comparing with a threshold value on a pre-stored histogram for the metallic or non-combustible material by A method for identifying a substance in a container, comprising identifying presence. 2. The method according to claim 2, wherein the metallic substance or the non-combustible substance in the container is
An apparatus for identifying a substance in a container, which is identified by X-ray projection, comprising: an X-ray projection apparatus including an X-ray generator and an X-ray detector; and a plurality of projection X-rays having different projection energies from the X-ray generator. Means for forming an X-ray fluoroscopic image, means for forming respective histograms from these X-ray fluoroscopic images, and forming a composite histogram from these histograms; A device for identifying a substance in a container, comprising: means for storing a threshold value; and means for transferring the threshold value and comparing with the composite histogram to identify the presence of the substance. 3. A method for incinerating a carton box in which low radioactive waste is sealed, wherein non-combustible substances in the carton box are identified by combining gray level data of the X-ray fluoroscopic image; Removing the carton box from the combustion stroke when identified. 4. A method for incinerating a carton box in which low-radioactive waste is sealed, comprising projecting X-rays from an X-ray generator onto said carton box to form an X-ray fluoroscopic image; And a non-combustible substance such as a metallic substance is identified from each of the X-ray fluoroscopic images, and each pixel of the X-ray fluoroscopic image is defined as a surface area, and a density is determined to obtain a minute volume. Removing the carton box from the combustion process if the volume of the substance is above a threshold value.