JP2010181412A - Method and device for discriminating and measuring radiation - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radiation discriminating/measuring device for irradiating a measuring object and discriminating and measuring α rays, β rays, γ rays, neutron beams, and X-rays contained in the obtained radiation. <P>SOLUTION: The measuring object 4, a first scintillator 7, a second scintillator 8, and a third scintillator 9 are arranged in a radiation irradiation region radiated from a radiation source. A light beam of a first wavelength region is emitted by the first scintillator 7, a light beam of a second wavelength region is emitted by the second scintillator 8, and a light beam of a third wavelength region is emitted by the third scintillator 9. The light emissions by the first, second and third scintillators are recognized by wavelength, and corrected. Measurements according to the types of the radiation are discriminated by wavelength and are performed simultaneously, thereby discriminating and measuring the types of the radiation, namely α rays, β rays, γ rays, neutron beams, and X-rays. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention is applied in industries and research institutions that handle radioactive materials, such as the nuclear power industry, radiology and radioactivity handling facilities, and any one of α rays, β rays, X rays, γ rays, or neutron rays is applied. The present invention relates to a radiation discrimination measurement method and a radiation discrimination measurement apparatus capable of discriminating and measuring each radiation from mixed radiation and performing a nondestructive test.

  When radiation passes through a substance, absorption and scattering differ depending on the type or shape of the constituent substance. If this is recorded as an image as a photograph, video, digital file or the like, it is possible to grasp the breakage state, change and filling state of the substance. This is generally the same principle as examining the internal state of the human body with radiographs. This method of measuring the internal state without destroying the object or sample to be measured is called radiography or non-destructive radiography.

  Conventionally, as such radiography, those using X-rays or γ-rays are well known. X-rays or γ-rays are used to examine the inside of an object because they pass through objects well and lighter objects are easier to transmit. However, X-rays or γ-rays are lighter and easier to transmit, so light elements with small atomic numbers are well transmitted. Therefore, hydrogen-containing substances hidden in metal materials are inspected. Was difficult. In addition, in X-rays or γ-rays, it is difficult to identify a minute difference such as elements having adjacent atomic numbers such as boron and carbon.

  On the other hand, radiography using neutrons instead of X-rays or γ-rays is used. In this radiography, the absorption of neutrons does not depend on the atomic number, and also passes through heavy materials, so light elements in metals that could not be identified by X-rays or γ-rays can be identified. . Further, the value of the absorption or scattering cross section for neutrons is unique to each element. For example, neutron absorption is large for boron, but not for carbon. For this reason, non-destructive inspection has been conducted to identify even light elements using neutrons.

  Currently, taking advantage of such radiography using X-rays or γ-rays and radiography using neutrons, radiography using both is used. Specifically, pyrotechnics, etc. Non-destructive inspection is conducted. According to the radiography combined with X-rays, γ-rays or neutrons, the same sample requires two operations of inspection with different X-rays, γ-rays or neutrons. It was complicated.

  As a method for eliminating such drawbacks, for example, as disclosed in JP-A No. 58-113842 (for example, Patent Document 1), Californium Cf.252 is used as a neutron source and a γ-ray source, A simultaneous radiography method has been proposed in which a γ-ray image detector and a neutron image detector are arranged side by side, a film is set on each detector, and an image is recorded simultaneously. However, even in such a method, since there are two films as images to be recorded, there is a problem in accurate alignment and image processing.

  Furthermore, this simultaneous radiography technique has been improved to measure γ-ray images and neutron images by color as disclosed in, for example, Japanese Patent Application Laid-Open No. 61-184444 (for example, Patent Document 2). A method has been proposed.

JP 58-113842 A Japanese Patent Laid-Open No. 61-184444 JP-A-4-290985

  However, the method as described above is excellent in that the γ-ray image and the neutron image can be measured by color, but has the following problems.

  In the above-mentioned simultaneous radiography in Japanese Patent Application Laid-Open No. 61-184444, a scintillator for γ-ray image emitting red light and a blue or green light emitting scintillator for neutron are combined on one film, A line image and a neutron image are measured.

  Actually, a scintillator for γ-ray images is obtained by applying or vapor-depositing a fluorescent material emitting red light on a heavy metal plate. On the other hand, as a scintillator for neutrons, a material containing lithium (Li-6) or boron (B-10) mixed with, or applied to, or vapor-deposited with a fluorescent material that emits blue or green light is used. The neutron is lithium or boron. And the (n, α) reaction occurs, and the blue (light emitting) fluorescent material is colored blue by the alpha (α) rays generated thereby. In addition, as this blue light-emitting fluorescent material, zinc sulfide ZnS: Ag activated with silver is used for the phosphor.

  As described above, in the method of recording neutron radiography in blue on one film and recording X-rays or γ-ray radiography in red to discriminate color, it is possible to correct the fog caused by X-rays and γ-rays. It was possible. In addition, this method has the advantage that the amount of irradiation with respect to X-rays or γ-rays is small by using a fluorescent material combined with the above-described zinc sulfide ZnS: Ag activated with silver. I was not fully satisfied.

  Moreover, since the scintillator to be used is not composed of a material that transmits γ rays and neutrons with respect to each other's wavelength, a film is sandwiched between the scintillator for γ ray images and the scintillator for neutrons, The scintillator had to be placed. For this reason, it is practically difficult to arrange three scintillators to emit light of a combination of three or more colors.

  In addition, when the film is disposed between, a general color film has an antihalation layer, and light from the back surface is not accurately recorded. For this reason, a special color film has to be used, which has a problem of high cost.

  On the other hand, in recent years, methods for improving the sensitivity in neutrons have been developed. For example, as disclosed in JP-A-4-290985 (for example, Patent Document 3), conventional lithium (Li An imaging plate for neutrons having higher sensitivity to neutrons compared to the type using −6) or boron (B-10) has been developed. This was developed by using the phosphor's stimulated luminescence, which is a phenomenon that emits light by stimulation such as heat and light after irradiation with an electron beam and radiation. Consists of a body applied. Specifically, this imaging plate is made of a sintered body using gadolinium (Gd) for reaction with neutrons and containing praseodymium (Pr), terbium (Tb) or europium (Eu) as an activator.

  The imaging plate described above has been further improved, and an imaging plate for neutrons and an imaging plate for neutrons composed of lithium (Li-6) that reacts with neutrons and boron (B-10) or gadolinium (Gd). Combinations have also been developed.

  Such an imaging plate for neutrons uses a stimulable phosphor, captures and stores a signal from ionizing radiation as a color center, and emits fluorescence with a laser beam from a reader to form an image. Although it is excellent in that the sensitivity is high and the work can be performed in a bright place, there is a problem in the real-time property in that the reading work must be performed separately after neutron irradiation. Further, since this technology was originally developed for X-rays, it has a problem that the sensitivity to X-rays and γ-rays is high, and the X-ray and γ-ray images cannot be distinguished from the neutron images. Even in this case, neutrons must be cut off and X-ray and γ-ray images must be taken separately for image processing, but such a method has not yet been developed.

  The present invention has been made to solve these problems, and when performing a nondestructive test for investigating the inside of a measurement object, alpha rays contained in radiation obtained by radiating the measurement object. , Β rays, γ rays, neutron rays, X-rays, and other radiation that can be discriminated as individual radiation, and that each radiation can be directly imaged and imaged without time lag It aims at providing a measuring device.

  It is another object of the present invention to provide a radiation discrimination measurement method capable of correcting the fog of a captured image and obtaining a highly sensitive image by improving the material constituting the scintillator and its thickness.

  In the radiation discrimination measurement method according to claim 1, a measurement object, a first scintillator, a second scintillator, and a third scintillator are arranged in a radiation irradiation region radiated from a radiation source. In the first scintillator, In response to the type A, type 光線 and type C of the radiation obtained by radiating the radiation emitted from the radiation source to the measurement object, the first scintillator emits light in the first wavelength range. In response to the types B and C of the radiation that is transmitted without being absorbed by the first scintillator, the second scintillator emits light in a second wavelength region different from the first wavelength region, and the third scintillator In response to the type C of radiation that is transmitted without being absorbed by the two scintillators, light of a third wavelength region different from the first and second wavelength regions is emitted, and the first, second and 3. Recognizing the light emission of the third scintillator by wavelength, correcting the data of the first scintillator with the data of the second and third scintillators, and correcting the data of the second scintillator with the data of the third scintillator Is characterized in that the measurement according to the type of radiation is discriminated by wavelength and measured simultaneously.

  In the present invention, scintillators having different emission wavelengths are used in combination for each of the radiation types A, B and C. In particular, the first scintillator is designed to be highly sensitive to the radiation A. However, since the first scintillator is strictly sensitive to the radiation types B and C, the result is that the radiation types B and C are somewhat covered. Therefore, the first scintillator has a thickness of the scintillator that can stop the radiation A almost 100%. For example, if the radiation type A is α-ray, the thickness of the scintillator may be several μm, and even in the case of β-ray, it can be stopped if the thickness is several tens of μm. In addition, the second scintillator is designed so as to increase the sensitivity with respect to the type B and type C of the radiation transmitted through the first scintillator, particularly with respect to the type B of radiation. For example, if the radiation type B is β rays or neutron rays shown later, it is sufficient that the thickness of the scintillator is several tens of μm. Conversely, if this scintillator is thickened, the sensitivity to X rays and γ rays is increased. It will be high. Finally, the third scintillator is designed so that the sensitivity is high with respect to the type C of radiation that is transmitted without being stopped by the second scintillator. However, since the type C of radiation passes through the first scintillator, the second scintillator, and the third scintillator, especially when the third scintillator is thickened, geometrical blur occurs and the resolution deteriorates. . If possible, it is better to use a thin third scintillator that is thin and highly sensitive to γ rays. The second and third scintillators are required to transmit sufficiently with respect to the first, second, and third emission wavelengths. The light emitted by the scintillator is recorded or observed for each emission wavelength, and each fog is corrected from image information for each color, and a signal based on pure radiation is extracted. For example, when the color emitted by the first scintillator is blue, the blue signal mainly includes information on the radiation A, but also includes information on the radiation trap and the radiation C. When the light emitted from the second scintillator is red, information on the radiation B and the radiation C is mainly obtained.

  In general, color signals of color televisions and the like are read and displayed as RGB signals of R: red, G: green, and B: blue. Therefore, it is possible to view the signals as RGB signals without performing image processing. However, in general, the sensitivity of each scintillator and the ratio to the type of radiation in the measurement environment are not constant, and need to be corrected. Since the information obtained by the third scintillator is only the information of the radiation C, the information of only the radiation B is obtained by subtracting the information of the third scintillator from the information obtained from the second scintillator evening. obtain. Since the information of the first scintillator includes three pieces of information of radiation A, soot and C, first, the information of the second scintillator (radiation soot, C) is subtracted from the information of the first scintillator. As a result, the information on the radiation B can be erased from the information on the first scintillator. At the same time, however, the radiation C information is also erased. For this reason, when the information of the radiation C is pulled too much, it can correct | amend with the information of only the radiation C obtained from the 3rd scintillator. In addition, once measurement is performed with a calibration indicator or the like, it is possible to simultaneously view information on the types of radiation A, Β and C from the next time.

  Therefore, according to the present invention, accurate information can be obtained by correcting the fog from the information obtained in the first, second and third scintillator evenings.

  The radiation discrimination measurement method according to claim 2 is the radiation discrimination measurement method according to claim 1, wherein the radiation type A is α-ray, the type Β is β-ray and the type C is γ-ray, and the first scintillator emits blue light. The second scintillator uses a red light emitter and the third scintillator uses a green light emitter, and α, β, and γ rays are simultaneously measured by color discrimination.

  The range of the range in the substance depending on the type of radiation is longer for β rays than for α rays and γ rays for longer than β rays. Therefore, the thickness of the scintillator is reduced from the radiation incident side, and the device is devised so that the thin scintillator can be sufficiently stopped as will be described later. In the opposite case, if the γ rays, β rays, and α rays are used in order from the radiation types A, B, and C, that is, if the first scintillator is optimized for γ rays, the β rays and α rays stop. The meaning after the second scintillator disappears, and wavelength discrimination based on the type of radiation becomes impossible.

  Therefore, in the present invention, by reducing the thickness of the scintillator from the radiation incident side, α rays, β rays and γ rays can be simultaneously measured by color discrimination.

  The radiation discrimination measurement method according to claim 3 is the radiation discrimination measurement method according to claim 1, wherein the radiation type A is β-ray, the type B is neutron radiation and the type C is γ-ray, and the first scintillator emits blue light. The second scintillator uses a red light emitter and the third scintillator uses a green light emitter, and β rays, neutron rays and γ rays are simultaneously measured by color discrimination.

  In the present invention, the case where α rays are excluded from the types of radiation is shown, and β rays, neutron rays and γ rays are sequentially formed from the types of radiation A, B and C. Neutron beams do not have a shorter range than γ-rays, but when gadolinium (Gd), which absorbs large neutrons, is used as a scintillator, gadolinium and neutrons react (n, γ) to generate electron beams. Get out. In the case of gadolinium, thermal neutrons are stopped almost 100% at several tens of μm. Further, since the range of this electron beam is about several tens of μm, several tens of μm is sufficient for causing the phosphor to emit light with the electron beam. For this reason, by devising a combination of these radiations, it becomes possible to use a scintillator having a different emission wavelength mainly composed of gadolinium, which is highly sensitive to γ rays.

  Therefore, also in the present invention, β rays, neutron rays and γ rays can be simultaneously measured by color discrimination.

  The radiation discrimination measurement method according to claim 4 is the radiation discrimination measurement method according to claim 2 or 3, wherein a combination of scintillators is changed, a blue light emitter is used as the first scintillator, a green light emitter is used as the second scintillator, In order from the red scintillator to the third scintillator, or red, blue, green, or red, green, blue, or green, red, blue, or green, blue, red in order from the first scintillator It is characterized by distinguishing the photographing results by the combination of colors.

  In the present invention, the second scintillator emits red light, the third scintillator emits green light, and vice versa. Therefore, by using the illuminant in an inverted manner according to the measurement, the difference in use conditions and use place can be expressed as a difference in color combination. For example, neutrons are recorded in red and γ rays are recorded in green at location a, while neutrons are recorded in green and γ rays are recorded in red at location b. Therefore, according to the present invention, it becomes possible to distinguish where the result is obtained even if data is mixed later by a combination of colors, and it is easy to organize.

  The radiation discrimination measurement method according to claim 5 is the radiation discrimination measurement method according to any one of claims 2 to 4, wherein a plastic scintillator, a glass scintillator, or a sintered body of a blue light emitter is used as the blue light emission scintillator. It is characterized by that.

  According to the present invention, the first scintillator emits blue light by using a plastic scintillator, a glass scintillator, or a sintered body of a blue light emitter as a blue light emission scintillator and devising to reduce the thickness. In addition, sufficient sensitivity to α rays and β rays can be obtained.

  A radiation discrimination measurement method according to claim 6 is the radiation discrimination measurement method according to any one of claims 2 to 4, wherein gadolinium activated with europium (Eu) or chromium (Cr) is used as a scintillator emitting red light. A red phosphor sintered body containing Gd) as a main component is used.

  In the present invention, in order to increase the sensitivity of the red light emitting scintillator and reduce the thickness of the scintillator, a phosphor mainly composed of gadolinium (Gd) having a large absorption cross-section with respect to thermal neutrons is selected. Used. Further, europium (Eu) or chromium (Cr) is selected and used as an activator in order to emit red light by an electron beam emitted in association with the (n, γ) reaction with thermal neutrons.

  Conventionally, for example, boron (B) and lithium (Li) have been used as main materials for reaction with thermal neutrons as scintillators that emit blue light. Both reactions with thermal neutrons are accompanied by (n, α) reactions. The phosphor was caused to emit light by the emitted α-rays. Since the range of α rays is shorter than that of γ rays, it is considered that the thickness of the blue light emitting scintillator can be reduced. However, the blue light emitting scintillator mainly composed of boron and lithium is the same as gadolinium in the present invention. Since the absorption cross-sectional area is small, the sensitivity decreases when the thickness of the scintillator evening is reduced. For this reason, the thickness of the scintillator evening cannot be reduced with the conventional material. Further, when used as the second scintillator, the neutron beam could not be completely stopped.

  Therefore, according to the present invention, by using a red phosphor sintered body mainly composed of gadolinium (Gd) as a red light emitting scintillator, the thickness of the scintillator can be reduced and the neutron beam can be completely obtained. It becomes possible to stop.

  The radiation discrimination measurement method according to claim 7 is the radiation discrimination measurement method according to any one of claims 2 to 4, wherein gadolinium activated with praseodymium (Pr) or terbium (Tb) as a scintillator emitting green light ( A green phosphor sintered body containing Gd) as a main component is used.

  Basically, when the scintillator becomes thicker, the distance between the subject to be measured and the light-receiving surface for recording increases and geometric blur increases. However, when the scintillator is for saddle and γ rays, the gadolinium ( By using a phosphor mainly composed of Gd), since the atomic number is particularly large, the interaction between X-rays and γ-rays is likely to occur, and the sensitivity can be increased even if the scintillator is thin. A phosphor was used.

  In addition, since the red light emission scintillator and the green light emission scintillator used for neutrons are placed together, the X-ray component and the γ ray component of the red light emission component can be corrected with substantially the same sensitivity. ) Was used as a main component.

  Furthermore, although related to the invention of claim 4 described above, it can be used in the same manner even if the red light emitting scintillator and the green light emitting scintillator are interchanged, and can also be used by being recombined for the neutron shown in the previous paragraph. A phosphor mainly composed of gadolinium (Gd) was used. When the red light emission scintillator and the green light emission scintillator are exchanged, the green color is the result of thermal neutrons and the red color is the result of γ rays.

  The radiation discrimination measurement method according to claim 8 is the radiation discrimination measurement method according to any one of claims 5 to 7, wherein the scintillator transmits a light emission wavelength of the scintillator to be combined.

  In the present invention, even when a scintillator is used in combination, radiation can be discriminated and measured by adopting a configuration that transmits the emission wavelength.

The radiation discrimination measurement method according to claim 9 is the radiation discrimination measurement method according to claim 5, wherein the blue phosphor is cerium activated yttrium aluminate YAlO ₃ : Ce, cerium activated yttrium silicate Y _2. SiO ₅ : Ce, gadolinium silicate activated with cerium Gd ₂ SiO ₅ : Ce, niobium activated yttrium tantalate YTaO ₄ : Nb, europium activated barium fluoride chloride BaFCl: Eu, activated with silver Zinc sulfide ZnS: Ag, calcium tungstate CaWO ₄ , cadmium tungstate CdWO ₄ , zinc tungstate ZnWO ₄ , or magnesium tungstate MgWO ₄ .

  According to the present invention, various materials described above can be applied as the blue phosphor.

The radiation discrimination measurement method according to claim 10 is the radiation discrimination measurement method according to claim 6, wherein the red phosphor is gadolinium borate GdBO ₃ : Eu activated with europium, gadolinium oxide Gd ₂ O activated with europium. ₃ : Eu, gadolinium oxysulfide activated with europium Gd ₂ O ₂ S: Eu, gadolinium aluminate activated with europium Gd ₃ Al ₅ O ₁₂ : Eu, gadolinium gallate activated with europium Gd ₃ Ga ₅ O ₁₂ : Eu, gadolinium vanadate GdVO ₄ activated with europium: Eu, and gadolinium gallium gallate Gd ₃ Ga ₅ O ₁₂ activated with cerium or chromium: Ce, Cr .

  According to the present invention, various materials described above can be applied as the red phosphor.

The radiation discrimination measurement method according to claim 11 is the radiation discrimination measurement method according to claim 7, wherein the green phosphor is terbium activated gadolinium oxide Gd ₂ O ₃ : Tb, terbium activated gadolinium oxysulfide Gd. ₂ O ₂ S: Tb, gadolinium oxysulfide activated with praseodymium Gd ₂ O ₂ S: r, gadolinium gallium gallate activated with terbium Gd ₃ Ga ₅ O 1 ₂ : Tb, gadolinium aluminate Gd ₃ activated with terbium It is any one of Al ₅ O ₁₂ : Tb.

  Also in the present invention, the various materials described above can be applied as the green phosphor.

  The radiation discrimination measurement method according to claim 12 is the radiation discrimination measurement method according to claim 1, wherein the radiation type A is neutron, the type B is X-ray and the type C is γ-ray, and the neutron, X-ray and γ-ray are detected. Simultaneously by color discrimination, or type A of radiation as low energy X-ray, type B as medium energy X-ray and type C as high energy X-ray or γ-ray, by X-ray energy or X-ray and γ-ray Are simultaneously measured by color discrimination.

  In the present invention, not only radiation such as α rays, β rays, and γ rays, but also X-ray energy can be measured simultaneously by color discrimination.

  The radiation discrimination measurement device according to claim 13 is a radiation source that emits radiation, and a radiation type A that is disposed in a radiation irradiation region emitted from the radiation source together with the measurement object and that has passed through the measurement object. A first scintillator that emits light in the first wavelength range in response to type IV and type C, and the first scintillator in response to type B and type C of radiation that is transmitted without being absorbed by the first scintillator. In response to a second scintillator that emits light in a second wavelength range different from the first wavelength range, and the type C of radiation that is transmitted without being absorbed by the second scintillator, the first and second A third scintillator that emits light in a third wavelength range different from the wavelength range, and recognizes light emission of the first, second, and third scintillators by wavelength, and data of the first scintillator An imaging unit that corrects with the data of the second and third scintillators, discriminates the measurement according to the type of radiation by the wavelength by correcting the data of the second scintillator with the data of the third scintillator, and measures simultaneously. Is provided.

  With the configuration according to the present invention, the above-described radiation discrimination measurement can be performed.

  The radiation discrimination measurement apparatus according to claim 14 is the radiation discrimination measurement apparatus according to claim 13, further comprising a color film for recognizing and recording for each wavelength as the imaging means.

  In the present invention, as an image pickup means for recording a signal emitted for each wavelength, a color film is used for recording on a single film. In the method using the conventional film method, an industrial X-ray film was used from the viewpoint of sensitivity and resolution of image quality, but because it was monochromatic, the wavelength component could not be divided and read from the recorded film. It was. Further, in the industrial X-ray film, the film surface is coated with emulsion on one side and both sides of the base film. Accordingly, recording is performed even if the scintillator is set in reverse, but in the case of a general color film, it is not possible to use a scintillator having a different emission color between the film. Therefore, as will be described later, it is configured to transmit the wavelengths emitted by the second and third scintillators. This is true even in the case of using a light receiving element such as a camera according to claim 11 or later described below.

  The radiation discrimination measurement apparatus according to claim 15 is the radiation discrimination measurement apparatus according to claim 13, further comprising, as an imaging unit, a photodetector such as a CCD camera or an imaging tube that recognizes and observes each wavelength. To do.

  A radiation discrimination measurement device according to claim 16 is the radiation discrimination measurement device according to claim 13, wherein a plurality of photodetectors are provided for each wavelength as a single color CCD camera or an imaging tube, and the light emission wavelength of each scintillator is separated. A dichroic mirror is provided.

  According to the fifteenth and sixteenth aspects of the present invention, a plurality of different wavelengths emitted by the scintillator can be directly observed using a CCD camera or an imaging tube as a photodetector instead of a color film. In particular, when a monochrome CCD camera or an imaging tube is used, a dichroic mirror having an optimized transmittance and reflectance according to the wavelength emitted by the scintillator is provided. As a result, the wavelength can be efficiently identified and observed. In order to simplify the photodetector, a three-plate CCD camera or a three-tube camera may be provided.

  The radiation discrimination measurement apparatus according to claim 17 is the radiation discrimination measurement apparatus according to any one of claims 14 to 16, wherein a color film, a CCD camera, or an imaging tube is installed as an imaging unit apart from a scintillator, An optical fiber for transmitting a signal of the scintillator is provided between the color film, the CCD camera or the imaging tube, and the scintillator.

  In the present invention, an optical fiber is installed between the emitted scintillator and a recording medium such as a film, an observation device such as a camera and a photomultiplier tube, and the optical signal is transmitted. Can be installed at a distance from the vessel. In particular, it is not necessary to use an optical imaging element such as a lens if a taper fiber is installed and brought into direct contact with the light receiving element of the camera.

  The radiation discrimination measurement apparatus according to claim 18 is the radiation discrimination measurement apparatus according to any one of claims 15 to 17, wherein the radiation discrimination measurement apparatus is replaced with an optical fiber, or together with an optical fiber, or attached to a CCD camera or an imaging tube. An image intensifier for amplifying the scintillator signal to increase sensitivity is provided.

  In the present invention, by using an image intensifier and a microchannel plate between the scintillator and the photodetector, it is possible to amplify a weak light emission optical signal and increase the sensitivity. Further, signal transmission loss can be reduced in combination with an optical fiber. When amplifying with a microchannel plate or the like, the red phosphor is used for the amplified phosphor, and when using a CCD camera, matching with the wavelength sensitivity characteristics (sensitivity peak near 700 nm) of the CCD camera is improved and sensitivity is improved. Is further improved.

  The radiation discrimination measurement device according to claim 19 is the radiation discrimination measurement device according to claim 14, wherein the image pickup means is an integral film attachment / detachment housing the color film and the first, second and third scintillators together. A possible imaging force cassette is provided.

  In the present invention, the color film is housed in an imaging power cassette that can block light together with a multicolor light emitting scintillator, and is integrated, and the film can be attached and detached. This eliminates the need for separate development by bringing together films that were previously separated for neutrons.

  The radiation discrimination measurement apparatus according to claim 20 is the radiation discrimination measurement apparatus according to claim 13, wherein a scintillator for thermal neutrons emitting red light or green light is applied to the first or second scintillator, respectively. A substance containing hydrogen is installed between one scintillator and the second scintillator, and thermal neutrons emitted by the first scintillator and fast neutrons emitted by the second scintillator are simultaneously measured for each emission wavelength. It is characterized by having a configuration to do.

  In the present invention, a scintillator for thermal neutrons emitting red light or green light is used for the first and second scintillators, and a resin containing hydrogen is inserted between the first scintillator and the second scintillator, The thermal neutron emitted by the scintillator and the fast neutron emitted by the second scintillator are simultaneously measured for each emission wavelength. At this time, the thickness of the scintillator is determined so that the first scintillator absorbs almost 100% thermal neutrons. For example, as described above, a thickness of several tens of μm is sufficient for a scintillator mainly composed of gadolinium (Gd) as a thermal neutron absorber. Fast neutrons are transmitted without being absorbed by the first scintillator. Therefore, the configuration is such that fast neutrons are decelerated with a resin containing hydrogen to form thermal neutrons, and light is emitted by the second thermal neutron scintillator.

  The radiation discrimination measuring apparatus according to claim 21 is installed for a plurality of optical fibers for transmission, a scintillator that emits light for each wavelength attached to each optical fiber, and other than the intended radiation around the scintillator. And each of the optical fibers is connected in series or in parallel.

  In the present invention, the scintillators are not combined to measure light by emitting light from one place, but are configured to individually attach scintillators that emit light according to wavelengths to optical fibers. A shielding material is provided around the individual scintillators in addition to the intended radiation, and transmission optical fibers are coupled in series or in parallel to measure the type of radiation by color. For this reason, according to this invention, it can be set as the structure which bundles an optical fiber, or can be arrange | positioned separately, and the application range to arrange | position becomes wide.

  As described above, according to the radiation discrimination measuring method and the radiation discrimination measuring apparatus according to the present invention, by combining scintillators having the same main component as the first, second, and third scintillators that emit light by different radiations. It was possible to record on a single color photograph in a short time, or to observe it with a CCD camera and instantly visualize it as a color image according to radiation. As a result, an inspection can be performed with a reduced amount of radiation applied to the measurement object, and the amount of exposure can be reduced and the measurement time can be shortened. In addition, since X-ray and γ-ray images and neutron images can be observed simultaneously or separately in a single measurement, plastic bombs, which could not be applied with conventional X-ray photography, can be Since the plastic body can be observed by neutron radiography, the quality and accuracy of inspection can be improved. In addition, when considered as a radiation measuring instrument, in addition to the conventional radiation discrimination method, a new wavelength discrimination method is added, so there are more ways to combine the discrimination, and a system that can measure many detectors together is built. By doing so, it can be expected to improve reliability and simplify the system.

The system block diagram which shows 1st Embodiment of this invention and shows the basic composition of neutron radiography. The enlarged view which shows an example of a structure in the imaging cassette of FIG. The system block diagram which shows 2nd Embodiment of this invention and shows the basic composition of neutron radiography. The enlarged view which shows an example of a structure in the imaging cassette of FIG. The figure which shows the modification of FIG. The figure which shows 3rd Embodiment of this invention. The figure which shows the 1st structural example by 4th Embodiment of this invention. The figure which shows the 2nd structural example by 4th Embodiment of this invention.

  Embodiments of the present invention will be described below with reference to the drawings. In addition, this embodiment is about the measurement example of the radioactive substance used in the nuclear industry. For example, the radiation type A is neutron, B is X-ray, and C is γ-ray. Neutron radiography will be described.

[First Embodiment (FIGS. 1 and 2)]
FIG. 1 shows the basic configuration of the neutron radiography according to the present embodiment, and FIG. 2 shows the main part of the imaging means therein.

  As shown in FIG. 1, in this embodiment, the radiation source is a neutron source 1, and this neutron source 1 is housed in a moderator 2 as a moderator. In some cases, the neutron beam irradiated from the neutron source 1 contains soot or γ rays. In the moderator 2, a collimator 3 is installed at the irradiation site of the neutron beam, and the measurement object 4 is irradiated with the neutron beam converged by the collimator 3, and imaging means is provided behind the measurement object 4. An imaging cassette 5 is arranged. As a result, the radiation (neutron, X-ray or γ-ray) transmitted through the measurement object 4 is detected as a radiation signal by the imaging cassette 5 and imaged.

  In this embodiment, as shown in the enlarged view of FIG. 2, the imaging cassette 5 has a configuration using a detachable color film 6 as a recording medium. The color film 6 includes a first scintillator 7 and a second scintillator 7. The scintillator 8 and the third scintillator 9 are arranged sequentially. Each of these scintillators 7, 8, 9 is configured to be thin so that each light emission can pass through each other.

The first scintillator 7 is composed of a red light emitter having high sensitivity to neutron radiation, for example, gadolinium oxysulfide (Gd ₂ O ₂ S) activated with europium (Eu), and has a thickness of, for example, 40 μm.

The second scintillator 8 is composed of a green light emitter having high sensitivity to X-rays, for example, gadolinium oxysulfide (Gd ₂ O ₂ S) activated with terbium (Tb), and has a thickness of several tens of μm.

  The third scintillator 9 is made of a blue light emitting body having high sensitivity to γ rays, for example, zinc sulfide (ZnS) activated with silver (Ag), and has a thickness of several tens of μm.

  As the first, second, and third scintillators 7, 8, and 9, it is possible to apply the other various light emitters described above, and in that case, the same function as in this embodiment can be obtained. it can. Further, as described above, various combinations of the red, blue, and green colors can be changed as described above.

  In this embodiment, when the green and blue light generated in the second and third scintillators 8 and 9 are transmitted through the first and second scintillators 7 and 8 and irradiated in the form of a film, information on each scintillator is obtained. It is exposed in the subtracted state.

  In FIG. 2, the color film 6 is shown as being set on the left side, which is the radiation incident side indicated by the arrow, with respect to each scintillator 7, 8, 9. , 9 may be set in the direction after radiation transmission, that is, on the right side of the figure.

  In the present embodiment, the color film 6 is developed and observed, or digitally processed by a scanner or the like and viewed as a radiation image for each wavelength. Therefore, by combining the first, second, and third scintillators 7, 8, and 9 that emit light with different radiations, it is possible to record a single color photograph in a short time, which could not be performed in the past, so that an instantaneous color image can be obtained for each radiation. Thus, it becomes possible to perform inspection by reducing the amount of radiation applied to the measurement object 4, thereby reducing the amount of exposure and shortening the measurement time.

[Second Embodiment (FIGS. 3 to 5)]
In this embodiment, a camera and an optical lens are used instead of the color film shown in the first embodiment, and an image is directly observed. FIG. 3 shows the overall configuration of the apparatus, and FIG. 4 shows an enlarged main part.

  As shown in FIGS. 3 and 4, in this embodiment, information of the first, second, and third scintillators 7, 8, and 9 that emit light by different radiation is used as an image signal by using a three-plate CCD camera 14. In addition, the image signal can be monitored by the remote control device 21 connected to the three-plate CCD camera 14. The remote control means 21 is constituted by a calculation means 22 that performs subtraction processing or the like from information of three types of colored light, a monitor television 23 that can display calculation results, and an input means 24 for operation.

  In this embodiment, since it can measure by remote control, it can measure without exposure and can shorten time. In addition, since the observed signal is captured as an RGB signal, the image processing can be instantaneously performed to correct fogging such as glazing and γ rays and irradiation unevenness in the irradiation area. Furthermore, since each color can be observed separately on the monitor television 23, there is an advantage that it is not necessary to align images having different wavelengths.

  FIG. 5 shows a modification of this embodiment.

  In this example, three single-color high-sensitivity CCD cameras 12 are used, and the first and second dichroic mirrors 10, which strictly separate only specific wavelengths from light of different wavelengths emitted by the scintillators 7, 8, 9. 11 for spectroscopic observation.

  That is, the first dichroic mirror 10 reflects the light from the first scintillator 7 and transmits the light from the second and third scintillators 8 and 9. The second dichroic mirror 11 reflects the light from the second scintillator 8 and transmits the light from the third scintillator 9. Images by these different lights can be obtained separately by the third CCD camera 12.

  According to such a configuration, the images obtained by each CCD camera 12 can be observed independently, and the image processing is instantaneously performed to cover fogging or γ rays or uneven irradiation of the irradiation area. It is also possible to correct. Moreover, the ratio of noise to signal (SIN) can be improved by using a dichroic mirror that strictly separates only a specific wavelength.

[Third Embodiment (FIG. 6)]
In the second embodiment described above, the CCD camera and the optical lens are used. However, in the present embodiment, an optical fiber is used instead of the optical lens. FIG. 6 shows the configuration of the main part.

  As shown in FIG. 6, in this embodiment, a large number of optical fibers, for example, a tapered fiber 13 having a larger cross-sectional area on the light entrance side than on the light exit side are bundled. The 3 scintillator 9 and the light receiving surface of the 3CCD camera 14 are directly connected.

  Even with such a configuration, substantially the same effects as those of the second embodiment can be obtained.

[Fourth Embodiment (FIGS. 7 and 8)]
In this embodiment, a plurality of scintillators that emit light according to wavelengths are attached to one or a plurality of optical fibers, radiation is directly input from each scintillator portion on the optical fibers, and optical information for each wavelength is obtained by a spectrometer. Information on each radiation is obtained by spectroscopic analysis.

  FIG. 7 shows a first configuration example.

  In the first configuration example, as shown in FIG. 7, a plurality of first and second scintillators 7a and 8a having different sensitive radiation and emission wavelengths are incorporated in one optical fiber 15 at adjacent positions. It is.

  The first scintillator 7a is sensitive to, for example, γ rays, and has a Cd shield 16 having a predetermined thickness for cutting thermal neutrons on the outer peripheral side. The second scintillator 8a is sensitive to neutrons on the contrary, and is coated with a Pb shield 17 having a predetermined thickness for cutting γ rays on the outer peripheral side. Both ends of the optical fiber 15 are connected to a spectrometer (not shown).

  Then, the light obtained by the first scintillator 7a is cut into thermal neutrons by the Cd shield 16 and mainly becomes an optical signal by γ rays, and is passed through one end side of the optical fiber 15 (for example, the left end side in the figure). It is sent to a spectrometer (not shown). The light obtained by the second scintillator 7b is cut by γ-rays by the Pb shield 17 to become an optical signal mainly by thermal neutrons, and is shown via the other end side (for example, the right end side) of the optical fiber 15. Don't be a spectrograph.

  According to such a configuration, the optical fiber 15 is configured in, for example, a loop shape, and the scintillators 7a and 7b are arranged in the radiation region, so that the radiation is remotely transmitted at a position separated from the radiation region. Observations can be made. In this case, although not shown, further radiation information can be obtained by incorporating a third scintillator together with the first and second scintillators 7a and 7b. At this time, a plurality of pieces of optical information are transmitted within one optical fiber 15, but can be discriminated by performing the same correction as in the above embodiments. Note that the scintillator is not limited to a single optical fiber, and can be arranged at a plurality of locations apart from each other. In that case, radiation observation can be performed on a plurality of regions.

  FIG. 8 shows another configuration example of the present embodiment.

  In this configuration example, as shown in FIG. 8, first, second, and third scintillators 7b and 8b having different radiations and emission wavelengths that are sensitive to each end of a plurality of, for example, three optical fibers 15, respectively. 9b are incorporated. The other end of each optical fiber 15 is connected to a photodetector (not shown).

  The first and second scintillators 7b and 8b have substantially the same configuration as that shown in FIG. 7, and are covered with a Cd shield 16 and a Pb shield 17, respectively. It is covered with a Cd cover 18 filled with a resin containing. As a result, thermal neutrons are cut by the Cd cover 18 and fast neutrons are converted into thermal neutrons by a resin containing hydrogen.

  According to such a configuration, a plurality of pieces of radiation information can be obtained by acquiring three types of light at one end of each optical fiber and detecting them with the photodetector at the other end. In this case, when the information obtained by the first, second, and third scintillators 7b, 8b, and 9b is fogged, accurate information can be obtained by performing the same correction as in the first embodiment.

  In the case of this configuration example, remote observation can be performed by arranging the tip of each optical fiber 15 provided with the scintillators 7b, 8b, and 9b in an arbitrary radiation region. As a result, it is possible to obtain accurate information.

  Although FIG. 8 shows an example using three optical fibers, depending on circumstances, two may be used, or four or more may be used.

[Other Embodiments]
In each of the above embodiments, an image intensifier can be inserted between the scintillator and the light receiving element to increase sensitivity.

  Moreover, the structure etc. which mutually combine the structure of each embodiment are also possible. For example, the resin layer shown in FIG. 8 is configured to be inserted between the second scintillator 8 and the third scintillator 9 shown in FIG. 2, FIG. 4, FIG. 5, FIG. Even in such a configuration, the same function as described above can be obtained.

  Further, in addition to the above-described embodiments, the present invention can be implemented in various ways according to the object or environment by appropriately using the above-described scintillator materials and the like.

DESCRIPTION OF SYMBOLS 1 Neutron source 2 Moderator 3 Collimator 4 Measurement object 5 Imaging cassette 6 Color film 7, 7a, 7b 1st scintillator 8, 8a, 8b 1st scintillator 9, 9a, 9b 1st scintillator 10, 11 Dichroic mirror 12 High sensitivity CCD Camera 13 Tapered fiber 14 Three-plate CCD camera 15 Optical fiber 16 Cd shield 17 Pb shield 18 Cd cover 21 Remote control device 22 Calculation means 23 Monitor TV 24 Input means

Claims (21)

An object to be measured, a first scintillator, a second scintillator, and a third scintillator are arranged in a radiation irradiation region radiated from the radiation source, and in the first scintillator, the radiation radiated from the radiation source is measured. The first scintillator emits light in the first wavelength band in response to the type A, type Β, and type C of the radiation obtained by irradiating the object, and the second scintillator transmits without being absorbed by the first scintillator. In response to the types B and C of the radiation to be emitted, the third scintillator emits light in a second wavelength region different from the first wavelength region, and is transmitted without being absorbed by the second scintillator In response to the type C, light of a third wavelength range different from the first and second wavelength ranges is emitted, and the emission of the first, second and third scintillators is recognized by wavelength. Then, the first scintillator data is corrected with the second and third scintillator data, and the second scintillator data is corrected with the third scintillator data to perform measurement according to the type of radiation. A radiation discrimination measurement method characterized by discriminating by wavelength and measuring simultaneously. The radiation discrimination measurement method according to claim 1, wherein the radiation type A is α-ray, the type Β is β-ray and the type C is γ-ray, the first scintillator is a blue light emitter, the second scintillator is a red light emitter, and A radiation discrimination measurement method, wherein a green light emitter is used as a third scintillator, and α rays, β rays and γ rays are simultaneously measured by color discrimination. The radiation discrimination measurement method according to claim 1, wherein the radiation type A is β-ray, the type B is neutron beam and the type C is γ-ray, the first scintillator is a blue light emitter, the second scintillator is a red light emitter, and A radiation discrimination measurement method, wherein a green light emitter is used as a third scintillator and β rays, neutron rays and γ rays are simultaneously measured by color discrimination. The radiation discrimination measurement method according to claim 2 or 3, wherein the combination of the scintillators is changed, the first scintillator is a blue light emitter, the second scintillator is a green light emitter, the third scintillator is a red light emitter, or In order from the first scintillator, red, blue, green, or red, green, blue, or green, red, blue, or green, blue, red are used in different combinations, and the result is a combination of colors. Radiation discrimination measurement method characterized by distinguishing by difference. 5. The radiation discrimination measurement method according to claim 2, wherein a plastic scintillator, a glass scintillator, or a sintered body of a blue light emitter is used as the blue light emission scintillator. 5. The method of measuring radiation discrimination according to claim 2, wherein the red phosphor scintillator is made of gadolinium (Gd) activated by europium (Eu) or chromium (Cr) as a main component. A radiation discrimination measurement method using a sintered body. 5. The radiation discrimination measurement method according to claim 2, wherein the green phosphor is composed of gadolinium (Gd) activated by praseodymium (Pr) or terbium (Tb) as a main component as a green light emission scintillator. A radiation discrimination measurement method using a sintered body. 8. The radiation discrimination measurement method according to claim 5, wherein the scintillator is configured to transmit the emission wavelength of the scintillator to be combined. 6. The radiation discrimination measurement method according to claim 5, wherein the blue phosphor is cerium activated yttrium aluminate YAlO ₃ : Ce, cerium activated yttrium silicate Y ₂ SiO ₅ : Ce, cerium activated silicic acid. Gadolinium acid Gd ₂ SiO ₅ : Ce, niobium activated yttrium tantalate YTaO ₄ : Nb, europium activated barium fluoride chloride BaFCl: Eu, silver activated zinc sulfide ZnS: Ag, calcium tungstate CaWO ₄ , Cadmium tungstate CdWO ₄ , Zinc tungstate ZnWO ₄ , or Magnesium tungstate MgWO ₄ . 7. The radiation discrimination measurement method according to claim 6, wherein the red phosphor is gadolinium borate GdBO ₃ : Eu activated with europium, gadolinium oxide Gd ₂ O ₃ activated with europium: Eu, oxysulfide activated with europium. Gadolinium Gd ₂ O ₂ S: Eu, europium activated gadolinium aluminate Gd ₃ Al ₅ O ₁₂ : Eu, europium activated gadolinium gallate Gd ₃ Ga ₅ O ₁₂ : Eu, europium activated vanadic acid Radiation discrimination measurement method characterized by being one of gadolinium GdVO ₄ : Eu and gadolinium gallate Gd ₃ Ga ₅ O ₁₂ : Ce, Cr activated with cerium or chromium. 8. The method according to claim 7, wherein the green phosphor is activated by terbium activated gadolinium oxide Gd ₂ O ₃ : Tb, terbium activated gadolinium oxysulfide Gd ₂ O ₂ : Tb, praseodymium. Gadolinium oxysulfide Gd ₂ O ₂ : Ρr, terbium activated gadolinium gallate Gd ₃ Ga ₅ O ₁₂ : Tb, terbium activated gadolinium aluminate Gd ₃ Al ₅ O ₁₂ : Tb A radiation discrimination measurement method characterized by the above. The radiation discrimination measurement method according to claim 1, wherein the type A of radiation is neutron, the type B is X-ray and the type C is γ-ray, and the neutron, X-ray and γ-ray are simultaneously measured by color discrimination, or the type of radiation. A is low energy X-ray, type B is medium energy X-ray and type C is high energy X-ray or γ-ray, and X-ray energy or X-ray and γ-ray are measured simultaneously by color discrimination. A radiation discrimination measurement method. A radiation source that emits radiation and a radiation irradiation region that is radiated from the radiation source are arranged together with the measurement object, and the first in response to the type A, type IV, and type C of the radiation that has passed through the measurement object. A first scintillator that emits light in a wavelength region of the second and a second wavelength region that is different from the first wavelength region in response to types B and C of radiation that is transmitted without being absorbed by the first scintillator A second scintillator that emits a light beam of the second and a light beam in a third wavelength region different from the first and second wavelength regions in response to a type C of radiation that is transmitted without being absorbed by the second scintillator A third scintillator that recognizes the light emission of the first, second, and third scintillators by wavelength, and the data of the first scintillator is the data of the second and third scintillators. Radiation discrimination characterized in that imaging means is provided that corrects and corrects the data of the second scintillator with the data of the third scintillator to discriminate measurement according to the type of radiation by wavelength and simultaneously measures measuring device. 14. The radiation discrimination measuring apparatus according to claim 13, further comprising a color film for recognizing and recording for each wavelength as an imaging unit. 14. The radiation discrimination measurement apparatus according to claim 13, further comprising: a photo detector such as a CCD camera or an imaging tube that recognizes and observes each wavelength as an imaging unit. 14. The radiation discrimination measuring apparatus according to claim 13, wherein a plurality of photodetectors are provided for each wavelength as a monochromatic CCD camera or an imaging tube, and a dichroic mirror for separating the emission wavelengths of each scintillator is provided. Discrimination measuring device. 17. The radiation discrimination measurement apparatus according to claim 14, wherein a color film, a CCD camera, or an imaging tube is installed as an imaging unit apart from a scintillator, and the color film, the CCD camera, or the imaging tube A radiation discrimination measuring apparatus comprising an optical fiber for transmitting a signal of the scintillator between the scintillator and the scintillator. 18. The radiation discrimination measurement apparatus according to claim 15, wherein the scintillator signal is amplified to increase sensitivity in place of an optical fiber, or together with an optical fiber, or attached to a CCD camera or an imaging tube. A radiation discrimination measuring device comprising an image intensifier of the above. 14. The radiation discrimination measurement apparatus according to claim 13, wherein the imaging means includes a film-type detachable imaging cassette that houses both the color film and the first, second, and third scintillators. A radiation discrimination measuring device. 15. The radiation discrimination measurement apparatus according to claim 14, wherein a scintillator for thermal neutrons of red light emission or green light emission is applied to the first or second scintillator, respectively, and the first scintillator and the second scintillator A radiation discrimination characterized in that a substance containing hydrogen is placed between the thermal neutrons emitted by the first scintillator and fast neutrons emitted by the second scintillator are simultaneously measured for each emission wavelength. measuring device. A plurality of optical fibers for transmission, a scintillator that emits light for each wavelength attached to each of the optical fibers, and a shielding material installed around the scintillator for other than the intended radiation, A radiation discrimination measuring device comprising optical fibers coupled in series or in parallel.

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