JP6629153B2 - Non-destructive inspection apparatus and method for nuclear fuel - Google Patents

Description

  An embodiment of the present invention relates to an apparatus and a method for nondestructively inspecting nuclear fuel for nondestructively inspecting nuclear fuel.

  An inspection method for non-destructively seeing through a substance includes, for example, a radiography method. The radiography method includes a neutron radiography method using a neutron as a radiation source. In the neutron radiography method, the reaction rate is different depending on the isotope of the same element without depending on the atomic number. Therefore, a neutron radiography method for imaging (imaging and visualizing) a plutonium mass called a plutonium spot from a neutron transmission reaction rate, particularly in heavy nuclides such as uranium and plutonium, has become promising. I have.

  Neutron radiography includes a direct method and an indirect method. The direct method includes a method in which a neutron-reactive substance converter and a film, and the converter and an imaging element such as a CCD (Charge Coupled Device) or a CMOS (Complementary Metal Oxide Semiconductor) are brought into close contact with each other. In this method, the film is exposed to γ-rays and X-rays when the subject itself has a high radioactivity, or in a high γ-ray environment field in the imaging environment. Further, in the image pickup device, damage may be caused by γ-rays or X-rays having relatively low energy, or the image pickup circuit itself may be damaged so that the image is not formed.

  In the indirect method, the radiation from the activated metal converter is transferred to a film in an environment that is not under a high dose and exposed, or a phosphor is emitted and the emission image is captured by an image sensor such as a CCD or CMOS. Or how to do it. Therefore, the indirect method enables imaging with neutrons without being affected by the subject itself or the surrounding γ-ray environment field.

JP-A-9-251089 JP 2012-47758 A

  By the way, in a nondestructive inspection of nuclear fuel or fuel debris during or after use, since the subject itself has high radioactivity, an image pickup device such as a film, a CCD or a CMOS, an imaging plate (hereinafter, referred to as IP) is used. The direct method of neutron radiography using a digital imaging device such as a flat panel detector (FPD) cannot be applied.

  In addition, the nuclear fuel during or after use, in which the subject itself emits strong γ-rays, may be stored in a γ-ray shielding container, or may be stored in water for both shielding and cooling. In these cases, neutrons can be transmitted through each shielding container so that imaging can be performed, or imaging can be performed by immersing a radiation source and a device such as a collimator in water.

  In particular, it is difficult to carry in a nuclear reactor or a large accelerator neutron source when photographing on site, so a small neutron source or a radioisotope (RI) neutron source such as Cf-252 is used. As a result, there is a problem that a neutron source having a low source intensity must be put into practical use.

  In addition, the indirect method of activating a metal converter and transferring it to a film requires an amount of radioactivity capable of sensitizing the film. Therefore, the neutron source intensity must be high.

  A problem to be solved by the present embodiment is to provide a non-destructive inspection apparatus and method for a nuclear fuel capable of identifying a specific nuclide without destroying a subject under a high radiation environment.

  In order to solve the above problems, a nondestructive inspection apparatus for nuclear fuel according to the present embodiment includes a shielding container for shielding radiation, a neutron source installed in the shielding container to generate neutrons, and a neutron source generated from the neutron source. A collimator that aligns the neutron flux that has been made, and a plurality of types of metal foil converters that are activated by neutrons transmitted through the neutrons whose nuclear flux has been collimated by the collimator and radiated to the subject of nuclear fuel, and the activated A detector that transfers radiation emitted from the plurality of types of metal foil converters and accumulates the radiation information as radiation information, an imaging unit that images the radiation information accumulated in the detector, and the plurality of types of metal foil converters. An arithmetic processing unit that performs arithmetic processing on the imaged image based on a difference in cross-sectional area depending on neutron energy.

  Further, the nondestructive inspection apparatus for nuclear fuel according to the present embodiment aligns a shielding container for shielding radiation, a neutron source installed in the shielding container to generate neutrons, and a neutron flux generated from the neutron source. A collimator, a plurality of types of metal foil converters that irradiate a neutron beam whose flux is aligned by the collimator to a subject of nuclear fuel and are activated by neutrons transmitted therethrough, and a neutron outlet of the collimator and the subject And a plurality of target nuclides having different thicknesses from each other, including a nuclide having an equivalent or isotope of the target nuclide of the subject or a nuclide having a neutron resonance spectrum of the target nuclide or an isotope element thereof A filter plate, a detector for transferring the radiation emitted from the activated metal foil converters and accumulating the radiation as radiation information, An imaging unit for imaging the radiation information accumulated in the output device, and the plurality of target nuclide filter plates having different thicknesses can be exchanged, and the imaged image is calculated based on the difference in thickness. And an arithmetic processing unit for processing.

  The non-destructive inspection method for nuclear fuel according to the present embodiment includes a step in which a collimator aligns a neutron flux generated from a neutron source, and a neutron beam which is transmitted by irradiating a neutron beam whose flux is aligned by the collimator to a subject of the nuclear fuel. An activation step of activating a plurality of types of metal foil converters at a transfer step of transferring radiation emitted from the activated plurality of types of metal foil converters to a detector and accumulating the radiation as radiation information; and An imaging step of imaging the radiation information accumulated in the vessel by an imaging unit, and an arithmetic processing unit is imaged based on a difference in cross-sectional area depending on neutron energy of the plurality of types of metal foil converters. And an arithmetic processing step of performing arithmetic processing on the image.

  Further, the nondestructive inspection method for nuclear fuel according to the present embodiment includes a step of aligning a neutron flux generated from a neutron source by a collimator, and irradiating a neutron beam whose flux is aligned by the collimator to an object of the nuclear fuel and transmitting the neutron beam. Activation step of activating a plurality of kinds of metal foil converters with neutrons, and a transfer step of transferring radiation emitted from the plurality of kinds of activated metal foil converters to a detector and accumulating the radiation as radiation information, The imaging step of imaging the radiation information accumulated in the detector by an imaging unit, an element of a target nuclide of the subject or an isotope element thereof, or a nuclide or a nuclide having a neutron resonance spectrum of the target nuclide A plurality of target nuclide filter plates having different thicknesses including isotope elements are exchanged, and the arithmetic processing unit is imaged based on the difference in the thickness. An arithmetic processing step of processing an image, that has the features.

  According to the present embodiment, it is possible to identify a specific nuclide in a high radiation environment without destroying the subject.

It is a plane sectional view showing a nondestructive inspection device of nuclear fuel of a 1st embodiment. FIG. 2 is an enlarged plan sectional view showing a configuration of a subject and a cassette in FIG. 1. It is a figure which shows the data of the neutron energy and cross section of uranium (U-235). It is a figure which shows the data of the neutron energy and cross section of uranium (U-238). It is a figure which shows the energy of the neutron, and the data of a cross section of plutonium (Pu-238). It is a figure which shows the energy and the cross-sectional area data of the neutron of plutonium (Pu-239). It is a figure which shows the data of the energy of a neutron, and a cross-sectional area of plutonium (Pu-240). It is a figure which shows the data of the neutron energy and cross section of dysprosium (Dy-164). It is a figure which shows the data of the neutron energy and cross section of gold (Au-197). It is a figure which shows the energy and cross-sectional area data of the neutron of indium (In-115). It is a figure which shows the data of the neutron energy of rhodium (Rh-103), and a cross section. It is a figure which shows the data of the neutron energy and cross section of cadmium (Cd-113). It is a plane sectional view showing a nondestructive inspection device of nuclear fuel of a 2nd embodiment.

  Hereinafter, a non-destructive inspection apparatus and method for a nuclear fuel according to the present embodiment will be described with reference to the drawings.

(1st Embodiment)
FIG. 1 is a plan sectional view showing a non-destructive inspection apparatus for a nuclear fuel according to a first embodiment. FIG. 2 is an enlarged plan sectional view showing the configuration of the subject and the cassette of FIG.

  As shown in FIG. 1, the nondestructive inspection apparatus of the present embodiment has a γ-ray shielding container 1 formed in a box shape having a rectangular cross section. A neutron shielding material 2 for shielding neutrons is provided on the entire inner peripheral surface of the γ-ray shielding container 1. On the inner surface on one side of the neutron shielding material 2, a neutron shielding material 2a is further provided. A reflector 3 for reflecting neutrons is provided on the inner peripheral surface of the neutron shield 2a. A small neutron source 5 as a neutron source is provided on the inner surface of the reflector 3 via a moderator 4.

  An entrance 6a of the collimator 6 is arranged near the neutron source 5. The collimator 6 is configured to be movable in the horizontal direction (the direction of the thick arrow) by a drive mechanism (not shown). That is, the collimator 6 is configured to be movable vertically by the driving mechanism with respect to the direction in which the neutrons pass.

  The small neutron source 5 includes, for example, a DD tube using a small DD (deuterium-deuterium) reaction or a DT tube neutron source using a DT (deuterium-tritium) reaction. Either an Inertial Electrostatic Confinement (IEC) fusion neutron source or a Cf-252 radioisotope (RI) neutron source is used.

  The reflecting material 3 can adjust the direction in which neutrons generated by the small neutron source 5 are emitted. The moderator 4 can adjust the energy of neutrons generated by the small neutron source 5. Therefore, neutrons generated by the small neutron source 5 have high energy. Therefore, the reflecting material 3 and the moderator 4 reduce the energy and output the neutrons in accordance with the energy region to be used, respectively.

  In the present embodiment, by adjusting the thickness of the moderator 4 or the stop position of the horizontally movable collimator 6, the energy region of the neutron beam 7 to be output and the mixing ratio of γ-rays can be selected.

  Specifically, when the thickness of the moderator 4 is small, the components of the epithermal region and the fast neutron region higher than the thermal neutrons are increased. Therefore, by disposing the entrance 6a of the collimator 6 off the axis in the neutron emission direction of the neutron source 1, the γ-ray component can be reduced and the thermal neutron region can be increased.

  The collimator 6 is made of a material whose material contains a large amount of boron or lithium. The collimator 6 has a cylindrical shape or a conical divergence type as in the present embodiment (divergent type: an area of the outlet 6b is larger than that of the inlet 6a). I do. The collimator 6 aligns the neutron flux generated from the small neutron source 5.

  The collimator 6 is formed by forming a peripheral wall surface with an aluminum structural material and storing a boron carbide or lithium fluoride material therein, or kneading boron carbide or lithium fluoride into an epoxy resin or polyethylene to vacuum remove. It is formed by foaming to reduce the internal voids.

  When an epoxy resin or polyethylene is used, a prompt γ-ray (2 Mev) is generated, which is released when a hydrogen component contained in the resin reacts with neutrons. When boron is used, 478 keV prompt γ-rays are generated.

  For this reason, a compound of lead or bismuth (for example, lead oxide or bismuth oxide) having a high γ-ray shielding effect is mixed with an epoxy resin or polyethylene, thereby shielding low energy components due to prompt γ-ray scattering and γ-rays from the external environment. A constituent material is used. These materials are also used for the neutron shielding materials 2 and 2a.

  The outlet 6 b of the collimator 6 extends into the subject shielding container 8. The subject shielding container 8 is installed on the inner surface on the other side of the neutron shielding material 2. A cassette 9 as a holding container is provided in the subject shielding container 8. In the subject shielding container 8, a subject 10 in which uranium (U) and plutonium (Pu), which are main elements of nuclear fuel components are mixed, is provided between the cassette 9 and the outlet 6b of the collimator 6. I have.

  In the present embodiment, plutonium (Pu) is detected as a target nuclide 10a from a subject 10 in which uranium (U) and plutonium (Pu) are mixed.

  The subject shielding container 8 is configured not to emit the gamma rays emitted from the subject 10 to the outside, and further surrounds the entire body including the prompt γ rays from the neutron shielding material 2 with the γ-ray shielding container 1.

  A plurality of metal foil converters 11 are housed in the cassette 9. Specifically, the metal foil converters 11 are stacked and arranged in a direction in which the neutron wires 7 pass. The metal foil converter 11 includes three types of metal foil converters 12, 13 and 14 according to the neutron resonance peak energy, as shown in FIG.

  These metal foil converters 12, 13, and 14 are stacked between the input side plate 15 and the holding plate 16 and react with the neutron beam 7 transmitted through the collimator 6. In the following, when the three types of metal foil converters 12, 13, and 14 are collectively described, the metal foil converter 11 will be described.

  The metal foil converters 12, 13, and 14 may be manufactured by rolling the thin film to a thickness of 300 μm or less, or may be manufactured by depositing metal foil on a base metal. The metal foil converters 12, 13, and 14 have a surface roughness accuracy of 100 μm or less.

  On the back surface of the holding plate 16, a closing lid 18 is provided via a holding spring 17. The cassette 9 is closed by the closing lid 18. When the cassette 9 is closed by the closing lid 18, the pressing spring 17 presses the back surface of the pressing plate 16. Thereby, metal foil converters 12, 13, and 14 are pressed against each other and held. In the present embodiment, the presser spring 17 is used to press the metal foil converters 12, 13, and 14 against each other, but an elastic member such as a sponge may be used instead.

  The three types of metal foil converters 12, 13, and 14 are irradiated with the neutron beam 7 transmitted from the small neutron source 5 through the collimator 6, and are activated. The three activated metal foil converters 12, 13, and 14 are taken out of the cassette 9. These metal foil converters 12, 13, and 14 are superimposed on IP19 as an example of a detector, transferred, and accumulated as radiation information.

  When the IP 19 is irradiated with radiation, energy is accumulated in the phosphor, and the phosphor (stimulable phosphor) emits light in accordance with the amount of absorbed radiation. When the irradiation of radiation is stopped, this light gradually weakens, but is excited again by irradiating a laser beam of a specific wavelength (for example, 630 nm) from a He-Ne laser light source even after a lapse of time. To emit light.

  The radiation information stored in the IP 19 is imaged by the imaging unit 20. Specifically, the imaging unit 20 reads a light amount by a reading device while irradiating a laser light emitted from a laser light source (not shown) with the light absorbed by the phosphor using a light emission phenomenon, thereby obtaining a digital image. Get as data.

  The arithmetic processing unit 21 performs arithmetic processing on digital image data imaged by the imaging unit 20 based on a difference in cross-sectional area depending on neutron energy of the plurality of metal foil converters 12, 13, and 14, which will be described later. Identify specific nuclides.

  The arithmetic processing unit 21 is configured by computer resources such as a personal computer. The arithmetic processing unit 21 reads out an operation program and various data stored in a storage medium such as a hard disk (not shown) by a computer and develops the program in a main memory, and the developed operation program is sequentially executed by a CPU (Central Processing Unit). I do.

  Next, the operation of the present embodiment will be described.

  FIGS. 3 to 7 are diagrams showing neutron energy and cross section data of uranium (U) and plutonium (Pu) isotopes. FIGS. 8 to 12 are graphs showing neutron energy and cross section data of dysprosium (Dy), gold (Au), indium (In), rhodium (Rh), and cadmium (Cd) isotopes.

  First, neutrons generated by the small neutron source 5 pass through the collimator 6 and become neutron beams 7 having uniform energy regions and directions. The neutron beam 7 is irradiated on the nuclear fuel of the subject 10, and the neutrons transmitted through the subject 10 are irradiated on the metal foil converters 12, 13, and 14 of the metal foil converter 11 in the cassette 9 to be activated.

  Here, three metal foil converters 11 to be irradiated are combined and laminated according to the neutron resonance peak energy. Specifically, in the present embodiment, dysprosium (Dy) foil is used for the metal foil converter 12, gold (Au) foil is used for the metal foil converter 13, indium (In) foil is used for the metal foil converter 14, and Dy is used for the neutron generation side. Lay it up so that the foil is positioned. In addition to these metal foils, for example, lutetium (Lu) foil, iridium (Ir) foil, and rhenium (Re) foil may be used.

  Next, the neutrons that have reacted with the nuclear fuel react with the metal foil converter 12 of the Dy foil located on the neutron generation side to activate the Dy foil. Then, it reacts with the metal foil converter 13 of Au foil and the metal foil converter 14 of In foil to activate each of them. Here, attention is paid to uranium (U) and plutonium (Pu) as main elements of the nuclear fuel component.

  Figures 3 to 7 show the figures (http://wwwndc.jaea.go.jp/NuC/index_J.html) of nuclear data released by the Nuclear Data Research Group of the Japan Atomic Energy Agency. These figures show the reaction rates of uranium (U) and plutonium (Pu) isotopes to neutron energy. Similarly, FIGS. 8 to 12 show the reaction ratios of neutrons to energy of Dy, Au, In, Rh, and Cd used as the activation foil.

In FIGS. 3-7, in particular focusing on the neutron energy 1 eV (10 ^0), although not resonance absorption peak of the neutrons in U nuclides, the Pu nuclide there is a strong resonance absorption peak reaction rate.

  This means that if the energy of the transmitted neutron is 1 eV, assuming that uranium (U) and plutonium (Pu) existing at the same density are mixed, the neutron transmitted through the plutonium (Pu) portion is React more, and the permeation amount is smaller than that in the state where the uranium (U) portion has passed. When the plutonium (Pu) is present at the spot, the amount of activation of the plutonium (Pu) portion is smaller than that of the uranium (U) portion, similarly to the case where a black portion becomes a shadow in a shadow picture, for example. In this case, it can be distinguished as imaging.

  Next, the transfer step of the metal foil converter will be described.

  The cassette 9 shown in FIG. 2 which has been irradiated with the configuration shown in FIG. 1 is removed, and the respective metal foil converters 12, 13, and 14 are transferred to the IP 19 in a superimposed manner. In this case, there is no gap between the metal foil converters 12, 13, and 14 and the IP19. In this case, the use of a vacuum cassette or a vacuum pack manufacturing machine capable of making the inside a vacuum state, which enhances the adhesion, can also reduce the penumbra (blur) of the image. Conversely, if the adhesion is low, the read image of IP19 becomes unclear.

  The transfer time between the metal foil converters 12, 13, and 14 and the IP 19 depends on the half-life of the metal foil element used, and is approximately in a saturated equilibrium state when the transfer time is about 5 times or more the half-life (radiation from the metal foil converter. The time when no longer appears). This transfer time is a reference time until reading of IP19.

  Further, when a plurality of metal foil converters 12, 13 and 14 are transferred, the setting of the resolution per pixel of the reading device is made the same, and the position information where the metal foil converters 12, 13 and 14 overlap is represented by IP19. It is transferred to the top and accumulated.

  The radiation information stored in the IP 19 is obtained as digital image data by reading the light amount with a reading device while irradiating the image forming unit 20 with laser light. Then, the digital image data imaged by the imaging unit 20 is arithmetically processed by the arithmetic processing unit 21 based on the difference in cross-sectional area depending on the neutron energy of the metal foil converters 12, 13, and 14, which will be described later. . This makes it possible to emphasize and display an image of only a specific neutron resonance absorption nuclide. As a result, a specific nuclide can be identified.

  As described above, according to the present embodiment, a plurality of types of metal foil converters 12, 13, and 14 are combined and activated by the small neutron source 5 at the site where the nuclear fuel inspection is performed. By transferring the foil converters 12, 13, and 14 to the IP 19 and performing arithmetic processing on the image read by the reading device, it becomes possible to identify a specific nuclide such as a plutonium spot.

(2nd Embodiment)
FIG. 13 is a plan sectional view showing a non-destructive inspection apparatus for a nuclear fuel according to the second embodiment. This embodiment is a modified example of the first embodiment, and the same parts as those in the first embodiment are denoted by the same reference numerals, and redundant description will be omitted.

  In the present embodiment, in addition to the configuration of the first embodiment, a plurality of target nuclide filter plates having different thicknesses are provided between the outlet 6b of the collimator 6 and the subject 10 in the subject shielding container 8. 25 are installed. These target nuclide filter plates 25 are arranged in the direction in which the neutron beam 7 passes, and are configured to be exchangeable in order to change the thickness. When the thickness is changed, the case where the target nuclide filter plate 25 is not installed is also included.

  The plurality of target nuclide filter plates 25 having different thicknesses are each composed of a target nuclide 10a of the subject 10 or an isotope element thereof, or a nuclide having a neutron resonance spectrum of the target nuclide 10a or an element containing the isotope element thereof. The thickness of the filter is provided.

  Next, the operation of the present embodiment will be described.

  The neutron irradiation method of the present embodiment is the same as in the first embodiment. The method of radiating the metal foil converter 11 by transmitting the object 10 and transferring it to the IP 19 is the same as in the first embodiment.

  By the way, in the present embodiment, a plurality of target nuclide filter plates 25, which are uniform plates of nuclides to be confirmed with the nuclear fuel, more specifically, isotope nuclides and have different thicknesses, are connected to the outlet 6b of the collimator 6 as described above. And the subject 10. In the present embodiment, the metal foil converter 11 is further activated by passing through the target nuclide filter plates 25 having different thicknesses (including a state without a filter plate) and further passing through the subject 10.

  In accordance with the plurality of target nuclide filter plates 25 having different thicknesses, neutrons in the resonance region of the same isotope as the target nuclide 10a have a difference in the permeation amount between isotopes in the nuclear fuel component of the subject 10. As a result, the amount of activation of the metal foil converter 11 also changes, and when the transferred radiation information of the IP 19 is imaged by the imaging unit 20, the density of the image also becomes different. Then, the difference between the obtained image data of the IP 19 is calculated by the calculation processing unit 21, so that the concentration of the isotope of the nuclide selected as the filter can be obtained.

  For example, suppose that the target nuclide 10a is Pu-240. From the data shown in FIG. 7, the resonance absorption peak of Pu-240 exists at 1 eV. Therefore, if Pu-240 is used for the target nuclide filter plate 25 having a different thickness, the neutron transmission amount changes depending on the thickness of the filter, and the Dy foil of the metal foil converter 12 or the In foil of the metal foil converter 14 is changed. Are activated and transferred to IP19 as in the first embodiment.

  The radiation information stored in the IP 19 is obtained as digital image data by reading the light amount with a reading device while irradiating the image forming unit 20 with laser light. The digital image data imaged by the imaging unit 20 is arithmetically processed by the arithmetic processing unit 21 based on the difference in the thickness of the target nuclide filter plate 25. This makes it possible to determine the distribution and amount of Pu-240 in the subject 10.

  However, instead of Pu-240 used here, In-115 shown in FIG. 10 and Rh-103 shown in FIG. 11 also have resonance absorption peaks near 1 eV, so the thickness of these nuclides was changed. With the filter as well, the amount of change of Pu-240 can be obtained in the same manner as described above.

  This means that the target nuclide 10a can be In-115 and the target nuclide filter plate 25 can be Rh-103. When the target nuclide 10a is Pu-239, Cd-113 can be used for the target nuclide filter plate 25.

  As described above, according to the present embodiment, a plurality of target nuclide filter plates 25 having different thicknesses are provided between the exit portion 6b of the collimator 6 and the subject 10, and the thicknesses of the target nuclide filter plates 25 are different. A specific nuclide can be identified in the same manner as in the first embodiment by performing an arithmetic process on the image based on the difference.

  In the present embodiment, the plurality of target nuclide filter plates 25 having different thicknesses may be changed, for example, by exchanging target nuclide filter plates having different thicknesses, or a plurality of target nuclide filter plates having the same thickness. The number of plates may be changed and replaced with a plate having a different thickness.

  In addition, the plurality of target nuclide filter plates 25 having different thicknesses from each other are changed in thickness by replacing the target nuclide filter plates with different thicknesses by removing some of the target nuclide filter plates, Alternatively, the thickness may be changed by replacing the plate with another target nuclide filter plate.

(Other embodiments)
Although embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These embodiments can be implemented in other various forms, and various omissions, replacements, changes, and combinations can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are also included in the invention described in the claims and their equivalents.

  For example, in each of the above embodiments, an example in which IP19 is used as the detector has been described. However, the present invention is not limited to this, and a stimulable phosphor, a film, a phosphor sheet, or the like may be used.

  In each of the above embodiments, the activated metal foil converter 11 is transferred by exposing the IP 19 to light. Alternatively, the metal foil converter 11 may be illuminated and transferred, or the excited state may be a CCD, The image may be transferred to an image sensor such as a CMOS.

  DESCRIPTION OF SYMBOLS 1 ... γ-ray shielding container (shielding container), 2, 2a ... Neutron shielding material, 3 ... Reflector, 4 ... Moderator, 5 ... Small neutron source (neutron source), 6 ... Collimator, 6a ... Inlet, 6b ... Exit part, 7 ... Neutron beam, 8 ... Subject shielding container, 9 ... Cassette (holding container), 10 ... Subject, 10a ... Target nuclide, 11 ... Metal foil converter, 12 ... Metal foil converter, 13 ... Metal foil converter , 14: metal foil converter, 15: input side plate, 16: holding plate, 17: holding spring, 18: closing lid, 19: IP (detector), 20: imaging unit, 21: arithmetic processing unit, 25: target Nuclide filter plate

Claims (10)

A shielding container for shielding radiation,
A neutron source installed in the shielding container to generate neutrons,
A collimator that aligns the neutron flux generated from the neutron source,
A plurality of types of metal foil converters, which are activated by neutrons transmitted by irradiating a neutron beam whose collimator has a uniform flux to a subject of nuclear fuel, and
A detector that transfers radiation emitted from the activated metal foil converters and accumulates the radiation as radiation information,
An imaging unit for imaging the radiation information accumulated in the detector,
An arithmetic processing unit that arithmetically processes the imaged image based on a difference in cross-sectional area depending on neutron energy of the plurality of types of metal foil converters,
A non-destructive inspection device for nuclear fuel, comprising: A shielding container for shielding radiation,
A neutron source installed in the shielding container to generate neutrons,
A collimator that aligns the neutron flux generated from the neutron source,
A plurality of types of metal foil converters, which are activated by neutrons transmitted by irradiating a neutron beam whose collimator has a uniform flux to a subject of nuclear fuel, and
The collimator is provided between the neutron outlet of the collimator and the subject, and is an element of the same or an isotope as the target nuclide of the subject, or a nuclide having a neutron resonance spectrum of the target nuclide or an element of the isotope thereof A plurality of target nuclide filter plates having different thicknesses from each other,
A detector that transfers radiation emitted from the activated metal foil converters and accumulates the radiation as radiation information,
An imaging unit for imaging the radiation information accumulated in the detector,
A plurality of target nuclide filter plates having different thicknesses are replaceable, and an arithmetic processing unit that performs arithmetic processing on the imaged image based on the difference in the thickness,
A non-destructive inspection device for nuclear fuel, comprising:   The neutron source includes a DD tube using a DD (deuterium-deuterium) reaction, a DT tube neutron source using a DT (deuterium-tritium) reaction, an inertial confinement nucleus. The non-destructive nuclear fuel inspection apparatus according to claim 1 or 2, wherein the apparatus is one of a fusion neutron source and a Cf-252 radioisotope neutron source.   The non-destructive inspection apparatus for a nuclear fuel according to claim 1, further comprising a holding container that holds the plurality of types of metal foil converters in a stacked manner.   The non-destructive inspection of nuclear fuel according to any one of claims 1 to 4, wherein the element of the metal foil of the plurality of types of metal foil converters is dysprosium, gold, indium, lutetium, iridium, or rhenium. apparatus.   The nuclear fuel nondestructive inspection device according to any one of claims 1 to 5, further comprising a drive mechanism for moving the collimator perpendicularly to a direction in which the neutrons pass.   The nuclear fuel nondestructive inspection apparatus according to any one of claims 1 to 6, wherein an entrance portion of the collimator is arranged to be shifted from a center of the neutron source.   The nuclear fuel nondestructive inspection device according to any one of claims 1 to 7, further comprising a moderator for adjusting energy of neutrons emitted from the neutron source. A collimator aligning the neutron flux generated from the neutron source; and
An activation step of activating a plurality of types of metal foil converters with neutrons transmitted by irradiating a neutron beam having a uniform flux with the collimator to a subject of nuclear fuel,
A transfer step of transferring radiation emitted from the activated plural kinds of metal foil converters to a detector and accumulating it as radiation information,
An imaging step of imaging the radiation information accumulated in the detector by an imaging unit,
An arithmetic processing unit that performs arithmetic processing on the imaged image based on a difference in cross-sectional area depending on neutron energy of the plurality of types of metal foil converters,
A nondestructive inspection method for nuclear fuel, comprising: A step of aligning the neutron flux generated from the neutron source by the collimator;
An activation step of activating a plurality of types of metal foil converters with neutrons transmitted by irradiating a neutron beam having a uniform flux with the collimator to a subject of nuclear fuel,
A transfer step of transferring radiation emitted from the activated plural kinds of metal foil converters to a detector and accumulating the radiation as radiation information,
An imaging step of imaging the radiation information accumulated in the detector by an imaging unit,
The target nuclide of the subject or an element of the isotope thereof, or a plurality of target nuclide filter plates different in thickness from each other including a nuclide having a neutron resonance spectrum of the target nuclide or an element of the isotope are replaced, and An arithmetic processing step in which an arithmetic processing unit performs arithmetic processing on the imaged image based on the difference in thickness,
A nondestructive inspection method for nuclear fuel, comprising:

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