Nondestructive inspection device

Abstract

A nondestructive inspection device (10) comprises: a neutron source (11); a gamma ray detector (12); a moderation unit (13a); and a reflection unit (13b). The neutron source 11 spontaneously generates neutrons. The gamma ray detector 12 detects gamma rays generated in an inspection object 1 due to neutrons entering the inspection object 1 located in front of the neutron source 11. The moderation unit 13a is disposed side by side to the gamma ray detector 12, is formed of a material that moderates neutrons, and covers the periphery of the neutron source 11 as viewed from the front. The reflection unit 13b is formed of a material that reflects neutrons, and covers the periphery of the moderation unit 13a excluding a prescribed region located closer to the gamma ray detector 12 as viewed from the moderation unit 13a.

Description

Non-destructive testing equipment

[0001] The present invention relates to a technique for inspecting an object based on gamma rays generated within the object by injecting neutrons into the object. This inspection may, for example, be an inspection of the integrity of the object (e.g., the presence or concentration of a target component within the object), but is not limited to this.

[0002] One of the factors causing deterioration of infrastructure structures such as roads and bridges (hereinafter referred to as infrastructure structures) is salt damage. Salt damage is caused by salt contained in sea breezes from the coast, or salt contained in de-icing agents sprayed in cold regions and mountainous areas. Such salt penetrates into concrete structures that make up infrastructure structures, for example. As a result, the chloride ion concentration around the reinforcing steel in the concrete structure reaches the limit value (1.2 to 2.5 kg / m³). ３ If the value exceeds the specified range, corrosion of the reinforcing steel will begin and progress, causing the concrete structure to deteriorate.

[0003] Therefore, it is important to inspect the salt concentration within concrete structures and repair them before corrosion begins. Such repairs can lead to cost reductions and extend the lifespan of concrete structures (such as the bridges mentioned above).

[0004] Patent documents 1 and 2 disclose non-destructive testing devices capable of non-destructively inspecting the presence and concentration of target components such as salt within concrete structures. The non-destructive testing devices of patent documents 1 and 2 enable the following inspections: Neutrons are incident on the object to be inspected. As a result, gamma rays originating from the target component are generated in the object by the neutrons. These gamma rays are detected, and based on the detection results, the depth at which the target component (e.g., salt) exists can be identified, and the concentration of the target component at that depth can be determined.

[0005] International Publication No. 2019 / 198260, Japanese Patent Publication No. 2021-179345

[0006] In some cases, non-destructive testing equipment, as described above, may need to be transported to the location where the object to be inspected will be inspected. For example, when inspecting infrastructure structures using non-destructive testing equipment, it is necessary to transport the equipment to the site. Furthermore, in order to inspect multiple locations on such an infrastructure structure, it is necessary to place the non-destructive testing equipment at each inspection location.

[0007] To facilitate the transportation and deployment of such non-destructive testing equipment, small and lightweight non-destructive testing devices are desirable. However, even when non-destructive testing devices are made smaller and lighter, it is desirable to improve the detection sensitivity of the target component.

[0008] Furthermore, when transporting non-destructive testing equipment to the location where the object to be inspected will be inspected, it is desirable to facilitate the transport and assembly of the non-destructive testing equipment.

[0009] Furthermore, when transporting and setting up non-destructive testing equipment at the location where the object to be inspected will be inspected, it is desirable to facilitate the connection between the various devices that process signals generated by gamma ray detection at that location.

[0010] When inspecting outdoor objects (e.g., infrastructure structures), it is desirable to be able to perform inspections even in rainy weather by preventing the main body of the non-destructive testing equipment from getting wet with rainwater.

[0011] Therefore, the first object of the present invention is to provide a technology that can improve the detection sensitivity of target components even when the non-destructive testing device is miniaturized and lightweight. The second object of the present invention is to provide a technology that facilitates the transport and assembly of the non-destructive testing device. The third object of the present invention is to facilitate the connection between the devices that process signals generated by gamma ray detection. The fourth object of the present invention is to prevent the main body of the non-destructive testing device from getting wet with rainwater, even in rainy weather, when inspecting objects to be inspected outdoors.

[0012] To achieve the first object of the present invention, a non-destructive testing apparatus according to one aspect of the present invention comprises: a neutron source that spontaneously generates and emits neutrons; a gamma-ray detector that detects gamma rays generated within an object to be inspected by neutrons incident on the object to be inspected in front of the neutron source; a deceleration unit arranged side-by-side with the gamma-ray detector in a direction lateral to the forward direction from the rear of the neutron source, formed of a neutron-decelerating material, and covering the periphery of the neutron source when viewed from the front; and a reflective unit formed of a neutron-reflecting material, covering the periphery of the deceleration unit except for a predetermined area on the gamma-ray detector side when viewed from the deceleration unit.

[0013] To achieve a second object of the present invention, a non-destructive testing apparatus according to another aspect of the present invention includes: a source unit including a neutron source that spontaneously generates and emits neutrons; a neutron shielding unit that shields the neutrons around the neutron source by covering it from the surroundings, thereby enabling the emission of neutrons toward the front of the neutron source; a main detector unit including a gamma-ray detector that detects gamma rays generated within an object to be inspected by neutrons incident on the object to be inspected toward the front of the neutron source; and a sub-detector unit including a sub-detector that outputs an incident signal when gamma rays are incident on it, wherein the source unit, the main detector unit, and the sub-detector unit are detachable from each other, and when attached to each other, the neutron shielding unit and the gamma-ray detector are positioned side by side, and the sub-detector is positioned around the gamma-ray detector.

[0014] To achieve a third object of the present invention, a non-destructive testing apparatus according to another aspect of the present invention comprises: a neutron source that spontaneously generates and emits neutrons; a neutron shielding unit that shields the neutrons around the neutron source by covering it from the surroundings, thereby enabling the emission of neutrons toward the front of the neutron source; and a gamma-ray detector that detects gamma rays generated within an object to be inspected by neutrons incident on the object to be inspected toward the front of the neutron source, and outputs a detection signal related to said detection, wherein the neutron shielding unit and the gamma-ray detector are arranged side by side in the lateral direction relative to the forward direction, with the direction from the rear to the front of the neutron source being the forward direction, and a sub-detector located around the gamma-ray detector, wherein when gamma rays are incident on the gamma-ray detector, the gamma-ray detector outputs an analog detection signal, and when gamma rays are incident on the sub-detector, the sub-detector outputs an analog incident signal. The non-destructive testing apparatus comprises: a detection amount measuring device that generates and outputs detection data of digital data indicating the amount of gamma rays detected at each energy of gamma rays based on each detection signal from the gamma-ray detector; and a rejection signal generation unit that, when an incident signal is output from the sub-detector, outputs a rejection signal to the detection amount measuring device indicating that the use of the detection signal is to be refused. In this case, the non-destructive testing apparatus comprises a data processing device that performs processing for inspecting the object to be inspected on the detection data from the detection amount measuring device, the detection amount measuring device and the rejection signal generation unit are made of hardware, and the data processing device may be a computer that operates by software.

[0015] To achieve a fourth object of the present invention, a non-destructive testing apparatus according to another aspect of the present invention comprises: a neutron source that spontaneously generates and emits neutrons; a neutron shielding unit that shields the neutrons around the neutron source by covering the neutron source from its periphery, thereby enabling the emission of neutrons toward the front of the neutron source; and a gamma-ray detector that detects gamma rays generated within an object to be inspected by neutrons incident on the object to be inspected toward the front of the neutron source, and outputs a detection signal related to the detection, wherein the direction from the rear to the front of the neutron source is considered the front direction, the neutron shielding unit and the gamma-ray detector are arranged side by side in the lateral direction relative to the front direction, the front side is upward, and the apparatus is provided with a waterproof cover that prevents rainwater from entering the main body by covering the main body, which includes the neutron source, the neutron shielding unit and the gamma-ray detector, from above and from the sides.

[0016] According to one aspect of the present invention, even when the non-destructive testing device is miniaturized and lightweight, the detection sensitivity of the target component can be improved. According to another aspect of the present invention, the transport and assembly of the non-destructive testing device can be made easier. According to another aspect of the present invention, in a non-destructive testing device, the connection between the devices that process signals generated by gamma ray detection can be made easier. According to another aspect of the present invention, when inspecting objects outdoors, the main body of the non-destructive testing device can be prevented from getting wet with rainwater, even in rainy weather.

[0017] The following are examples of the configuration of a non-destructive testing apparatus according to the first embodiment of the present invention. This is a plan view taken along the line 1B-1B in Figure 1A. This is a horizontal cross-sectional view taken along the line 1C-1C in Figure 1A. This is an explanatory diagram of the shape of the gamma-ray shielding section. This is a more detailed configuration diagram of the non-destructive testing apparatus. This shows the dimensions of each part in the non-destructive testing apparatus of the embodiment. This shows the dimensions of each part when the reflective section is provided around the entire periphery of the deceleration section in the neutron shielding section. The following are examples of the configuration of a non-destructive testing apparatus according to the second embodiment of the present invention. This shows the case where the main detector unit is located at the bottom in Figure 4A. This shows an example of the configuration of the radiation source unit. This is a view taken along the line 5B-5B in Figure 5A. This shows an example of the configuration of the main detector unit. This is a view taken along the line 6B-6B in Figure 6A. This shows an example of the configuration of the sub-detector unit. This is a view taken along the line 7B-7B in Figure 7A. This shows an example of the configuration of the support structure. This shows the case where the second mounting section is located at the bottom in Figure 8A. This shows an example of the configuration of the attachment / detachment device. This shows the state in which the first base and the first mounting section are separated in Figure 9A. This shows a configuration in which the second mounting part slides. Figure 10A shows the case where the main detector unit and the second mounting part are located downwards. This is a block diagram showing a configuration for processing the detection signal from the gamma-ray detector. This shows an example of a waterproof cover configuration to prevent rainwater from entering the main body of the non-destructive testing device. This shows a perspective view of the waterproof cover. This is an exploded view of the waterproof cover. This shows an example of a configuration according to modification example 3. This is a view taken along the 14B-14B arrow in Figure 14A. Figure 14A shows the state in which the closing member, reduction unit, and second block body have been removed. Figure 14B shows the state in which the closing member, reduction unit, and second block body have been removed. Figure 15B shows the state in which the reduction unit has been installed. Figure 15C shows the state in which the second block body has been installed.

[0018] Embodiments of the present invention will be described with reference to the drawings. Common parts in each figure are denoted by the same reference numerals, and redundant explanations are omitted. In some cases, only a portion of the figure may be shown in cross-section for convenience.

[0019] [First Embodiment] Figure 1A shows an example of the configuration of a non-destructive testing apparatus 10 according to an embodiment of the present invention. Figure 1B is a plan view taken along the line 1B-1B in Figure 1A, and Figure 1C is a horizontal cross-sectional view taken along the line 1C-1C in Figure 1A. Note that Figure 1A is a cross-sectional view taken along the line 1A-1A in Figure 1C.

[0020] The non-destructive testing apparatus 10, during inspection, incidents a neutron beam onto the surface 1a of the object to be inspected 1, detects the gamma rays generated in the object to be inspected 1, generates a detection signal related to the detection, and obtains detection data based on the detection signal. In this specification, inspection means that the non-destructive testing apparatus 10 incidents a neutron beam onto the surface 1a of the object to be inspected 1 and detects the gamma rays generated in the object to be inspected 1.

[0021] The object to be inspected 1 is a concrete structure containing reinforcing bars (for example, a concrete structure that makes up a bridge), and the target component may be salt (chlorine). When the target component is salt, the salt is, for example, a stable isotope of chlorine Cl. ３５ It may be Cl. Furthermore, the object to be inspected 1 and the target component are not limited to the combination of concrete structure and salt. That is, object to be inspected 1 is not limited to concrete structure. The target component is also not limited to chlorine (Cl), but for example, calcium (mainly ４０ Ca), silicon (mainly ２８ Si), or hydrogen ( １ H) is also acceptable. The object to be inspected 1 may be something other than an infrastructure structure such as a concrete structure, as described above.

[0022] (Components of the non-destructive testing apparatus) The non-destructive testing apparatus 10 comprises a neutron source 11, a gamma-ray detector 12, a neutron shielding unit 13, a gamma-ray shielding unit 14, and first and second neutron absorption units 15 and 16.

[0023] Neutron source 11 is a radioisotope (RI) neutron source that spontaneously generates and emits neutrons (neutron radiation). This RI source may be a spontaneous fission neutron source. The RI source is californium ( ２５２ It may be Cf). However, according to the present invention, the RI source is not limited to this, and may be, for example, an Am-Be neutron source.

[0024] The gamma-ray detector 12 detects gamma rays generated by neutrons from the neutron source 11 in the object under inspection 1 and outputs a detection signal related to the detection. That is, the gamma-ray detector 12 detects gamma rays when they are incident on it and outputs a detection signal each time it detects gamma rays. This detection signal indicates that the gamma rays were incident on the gamma-ray detector 12 and includes information indicating the energy of the gamma rays. For example, this detection signal may be a waveform signal having a peak value corresponding to the energy of the gamma rays.

[0025] The gamma-ray detector 12 may be a germanium semiconductor detector composed of a germanium semiconductor. In this case, the gamma-ray detector 12 may be used in a state cooled by a cryogenic liquid (e.g., liquid nitrogen). That is, as shown in Figure 1A, the gamma-ray detector 12 may be used in a state cooled by the cryogenic liquid via a cold finger (copper rod) 18 immersed in the cryogenic liquid in a dewar 17. Such a gamma-ray detector 12 may be housed in a container 12v (e.g., a vacuum chamber). For convenience, in each figure, the gamma-ray detector 12 inside the container 12v is shown as a transparent view.

[0026] Instead of cooling the germanium semiconductor detector 12 with an cryogenic liquid as described above, an electric cooler may be provided to electrically cool the germanium semiconductor detector 12. In this case, the electric cooler may be supported by the support 31 described later.

[0027] The gamma-ray detector 12 may be made of a semiconductor material other than germanium (for example, Si, CdTe, CdZnTe), or it may be made of a scintillation detector (for example, NaI(Tl), BGO, CsI).

[0028] The neutron shielding section 13 is made of a material that shields neutrons. The neutron shielding section 13 shields the neutron source 11 from all sides and from the rear, thereby shielding neutrons from all sides and allowing neutrons from the neutron source 11 to be emitted forward. In this state, the neutron source 11 may be attached to the neutron shielding section 13 (the deceleration section 13a described later). With the direction from the rear to the front of the neutron source 11 being defined as the forward direction, the gamma-ray detector 12 and the neutron shielding section 13 are arranged side by side in the lateral direction relative to the forward direction (left-right direction in Figure 1A).

[0029] In this specification, the forward direction may be the direction in which the neutron emission surface 13a1 of the deceleration unit 13a, described later, faces (a direction perpendicular to the neutron emission surface 13a1), and the lateral direction may be a direction perpendicular to the forward direction. Furthermore, in this specification, in the non-destructive testing apparatus 10, when a certain component (e.g., neutron source 11) is covered by another component (e.g., neutron shielding unit 13) from around it, it may mean, but is not limited to, that the certain component is covered by the other component in each direction perpendicular to the forward direction (e.g., all directions perpendicular to the forward direction).

[0030] The neutron shielding section 13 may be configured to include a deceleration section 13a and a reflection section 13b.

[0031] The deceleration unit 13a is made of a material that decelerates neutrons (a neutron moderator that lowers the energy of neutrons). The neutron moderator may be a material that does not readily absorb neutrons. The neutron moderator is, for example, polyethylene, but other materials may also be used. The neutron moderator may be a material that absorbs neutrons less readily than the material of the first neutron absorption unit 15, which will be described later.

[0032] The deceleration unit 13a covers the neutron source 11 from all sides (the entire surroundings) and from the rear. Alternatively, the neutron source 11 may be positioned at the front end of the deceleration unit 13a. In this case, the neutron source 11 does not need to be covered by the deceleration unit 13a from the front side (the side facing forward). In this case, the neutron source 11 may be exposed to the surface 1a of the object to be inspected 1 in the forward direction during inspection.

[0033] More specifically, a recess 13a2 is formed in the neutron emission surface 13a1, and the neutron source 11 may be placed in this recess 13a2. As a result, the neutron source 11 is covered on its periphery and rear by the deceleration section 13a. The recess 13a2 may have a shape that matches the neutron source 11 and may be open to the front. The neutron source 11 may be joined to the deceleration section 13a.

[0034] When viewed in the opposite direction to the forward direction (i.e., the backward direction), the neutron source 11 is positioned offset from the center of the deceleration unit 13a in the lateral direction towards the gamma-ray detector 12. This shortens the lateral distance between the neutron source 11 and the gamma-ray detector 12. However, the position of the neutron source 11 in the lateral direction is not limited to this; for example, it may be located in the center of the deceleration unit 13a in the lateral direction. The neutron source 11 and the gamma-ray detector 12 may be positioned on the same virtual plane parallel to both the forward and lateral directions (left-right direction in Figure 1A).

[0035] The deceleration unit 13a has a neutron emission surface 13a1 facing forward. The neutron emission surface 13a1 also emits forward neutrons that have traveled through the deceleration unit 13a to the reflection unit 13b, been reflected by the reflection unit 13b, and returned to the deceleration unit 13a one or more times from the neutrons emitted from the neutron source 11.

[0036] The reflective section 13b is formed of a neutron reflector, which is a material that reflects neutrons. The neutron reflector may be a material that does not easily absorb neutrons. In this embodiment, the neutron reflector is graphite, but other materials may be used. The neutron reflector may be a material that reflects neutrons more easily than the material of the deceleration section 13a. Furthermore, the neutron reflector may be a material that absorbs neutrons less easily than the material of the first neutron absorption section 15, which will be described later.

[0037] According to the present embodiment, the reflecting portion 13b covers the periphery of the moderating portion 13a excluding a predetermined region on the side of the gamma-ray detector 12 as viewed from the moderating portion 13a. The predetermined region may be, for example, the region occupied by the first neutron absorbing portion 15 described later in each figure. In the present embodiment, since the reflecting portion 13b does not exist in the predetermined region on the side of the gamma-ray detector 12 as viewed from the moderating portion 13a, (compared with, for example, the case of FIG. 3C described later), by that amount (for example, by the lateral dimension of the predetermined region), the lateral distance between the neutron source 11 and the gamma-ray detector 12 can be shortened.

[0038] Such a reflecting portion 13b may not have a portion overlapping the moderating portion 13a in the lateral direction on the side of the gamma-ray detector 12 with respect to the moderating portion 13a. Therefore, in the moderating portion 13a, the surface facing the gamma-ray detector 12 (for example, the surface facing the lateral direction on the side of the gamma-ray detector 12) may not be covered by the reflecting portion 13b. Further, the reflecting portion 13b may not have a portion overlapping the first neutron absorbing portion 15 described later in the lateral direction on the side of the gamma-ray detector 12 with respect to the moderating portion 13a.

[0039] The front surface of the moderating portion 13a facing the forward direction (that is, the neutron emission surface 13a1) and the front surface 13b1 of the reflecting portion 13b facing the forward direction may form substantially the same virtual surface (plane). In this case, the tip (front surface) of the neutron source 11 in the forward direction may be located on the same virtual surface. Each of the front surfaces 13a1 and 13b1 may be a plane, but is not limited thereto and may be a curved surface.

[0040] The gamma-ray shielding portion 14 is disposed between the first neutron absorbing portion 15 and the gamma-ray detector 12 in the lateral direction and shields gamma rays. The gamma-ray shielding portion 14 is formed of a material that shields gamma rays. The material may be, for example, lead, but may be other materials.

[0041] As shown in FIG. 1A, the gamma-ray shielding portion 14 may have an inclined surface 14a as its front end surface. The inclined surface 14a faces in a direction inclined toward the gamma-ray detector 12 from the front direction. Further, the inclined surface 14a extends so as to approach the gamma-ray detector 12 as it shifts from the tip on the front side of the gamma-ray shielding portion 14 to the side opposite to the front direction. In other words, in the front side portion of the gamma-ray shielding portion 14, the area of the cross-section of the gamma-ray shielding portion 14 by a plane orthogonal to the front direction gradually decreases as it shifts to the front side.

[0042] The first neutron absorption portion 15 is disposed between the deceleration portion 13a and the gamma-ray shielding portion 14 in the lateral direction. The first neutron absorption portion 15 is formed of a material different from that of the deceleration portion 13a and the reflection portion 13b. The first neutron absorption portion 15 is formed of a material that absorbs neutrons. The material may be boron carbide (B ４ C). For example, the first neutron absorption portion 15 may be formed of a rubber containing B ４ C. However, as long as the material of the first neutron absorption portion 15 is a material that absorbs neutrons, it may be other than B ４ C.

[0043] The first neutron absorption portion 15 may be disposed in the above-described predetermined region. Further, the first neutron absorption portion 15 may be sandwiched by the reflection portion 13b in the vertical direction (hereinafter also simply referred to as the vertical direction) orthogonal to both the front direction and the lateral direction. For example, the first neutron absorption portion 15 may be sandwiched by the end portions on the gamma-ray detector 12 side in the reflection portion 13b and spaced apart from each other in the vertical direction. Such a first neutron absorption portion 15 may constitute a neutron shielding portion 13 that covers the periphery of the neutron source 11 together with the above-described deceleration portion 13a and reflection portion 13b.

[0044] Further, the first neutron absorption portion 15 may directly cover the deceleration portion 13a from the side of the gamma-ray detector 12. In this case, there may be no other members including the reflection portion 13b between the first neutron absorption portion 15 and the deceleration portion 13a in the lateral direction. In this case, the first neutron absorption portion 15 may be in contact with the deceleration portion 13a.

[0045] The deceleration section 13a, the reflection section 13b, the gamma-ray shielding section 14, and the first neutron absorption section 15 may each be formed as separate components and then assembled together.

[0046] The second neutron absorption section 16 covers the gamma-ray detector 12 from the front and also covers the gamma-ray detector 12 from the neutron shielding section 13 side. The second neutron absorption section 16 comprises a front absorption section 16a and a side absorption section 16b. The front absorption section 16a extends laterally to cover the gamma-ray detector 12 from the front. The side absorption section 16b extends forward to cover the gamma-ray detector 12 laterally from the neutron shielding section 13 side. The lateral end of the front absorption section 16a on the neutron shielding section 13 side is connected to the front end of the side absorption section 16b. The front absorption section 16a may be omitted, in which case the second neutron absorption section 16 consists only of the side absorption section 16b.

[0047] The second neutron absorption section 16 may be positioned closer to the gamma-ray detector 12 than the gamma-ray shielding section 14. The second neutron absorption section 16 (i.e., the front absorption section 16a and the side absorption section 16b) is made of a neutron-absorbing material. In this embodiment, the material is one that absorbs neutrons but does not easily generate gamma rays from incident neutrons. In this case, the material may be lithium fluoride (LiF). However, the material of the second neutron absorption section 16 may be a suitable material other than LiF.

[0048] The front surface of the non-destructive testing device 10 may be configured such that the front surface (front surfaces 13a1, 13b1) of the forward-facing neutron shielding section 13, the front end (forward-facing end) of the gamma-ray shielding section 14, the front surface 15a of the forward-facing first neutron absorption section 15, and the front surface 16a1 of the forward-facing forward absorption section 16a are substantially included in the same virtual plane (plane). This makes it easier to bring the entire front surface of the non-destructive testing device 10 close to the surface 1a1 of the object to be inspected 1.

[0049] In this embodiment, the gamma-ray detector 12, the neutron shielding unit 13 (deceleration unit 13a), the gamma-ray shielding unit 14, the first neutron absorption unit 15, and the lateral absorption unit 16b are arranged side by side in the lateral direction, at least in part. That is, the gamma-ray detector 12, the neutron shielding unit 13 (deceleration unit 13a), the gamma-ray shielding unit 14, the first neutron absorption unit 15, and the lateral absorption unit 16b overlap each other at least partially in the lateral direction.

[0050] In this case, when viewed from the side, the gamma-ray detector 12, the gamma-ray shielding section 14, and the lateral absorption section 16b may be arranged side by side so that, when viewed from the side, all or part of each of them is included within the range of the neutron shielding section 13.

[0051] (Dimensions, shape, etc. of the gamma-ray shielding section) The dimensions, shape, and arrangement of the gamma-ray shielding section 14 may be set so that the entire gamma-ray detector 12 is hidden by the gamma-ray shielding section 14 no matter what viewpoint (position) from which the gamma-ray detector 12 is viewed in the deceleration section 13a. The positions of the front end surface (slope) 14a and the rear end surface 14b of such a gamma-ray shielding section 14 will be explained based on Figure 1D. Figure 1D corresponds to Figure 1A, and is an explanatory diagram of the front end surface (slope) 14a and the rear end surface 14b.

[0052] The front reference plane P1 (the dashed line in Figure 1D) is defined as a virtual plane tangent to both the front portion of the gamma-ray detector 12 and the front portion of the deceleration unit 13a. Each position on the inclined surface 14a of the gamma-ray shielding unit 14 may be included in the reference plane P1 or located in front of the reference plane P1. In this case, the inclined surface 14a may be formed so that its entirety is included in the reference plane P1.

[0053] Similarly, the virtual plane that is tangent to both the rear portion of the gamma-ray detector 12 and the rear portion of the deceleration unit 13a is defined as the rear reference plane P2 (the dashed line in Figure 1D). Each position on the rear end surface 14b of the gamma-ray shielding unit 14 may be included in the reference plane P2 or located behind the reference plane P2. In this case, the rear end surface 14b may be formed so that its entirety is included in the reference plane P2.

[0054] Furthermore, if the entire gamma-ray detector 12 is hidden by the gamma-ray shielding section 14 from any viewpoint (position) in the deceleration section 13a, the vertical dimension of the gamma-ray shielding section 14 may be smaller than the vertical dimension of the deceleration section 13a, as shown in Figure 1C. This makes it possible to increase the amount of gamma rays incident on the gamma-ray detector 12 from the object under inspection 1 while shielding the gamma rays from the deceleration section 13a to the gamma-ray detector 12. In this case, the vertical dimension of the gamma-ray shielding section 14 may decrease as it moves horizontally toward the gamma-ray detector 12, as shown in Figure 1C, or it may remain constant. However, the vertical dimension of the gamma-ray shielding section 14 is not limited to these dimensions and may be greater than or equal to the vertical dimension of the deceleration section 13a.

[0055] Furthermore, if a distance adjustment mechanism is provided that allows adjustment of the lateral distance between the gamma-ray detector 12 and the neutron shielding section 13 and the gamma-ray shielding section 14, the dimensions, shape, and arrangement of the gamma-ray shielding section 14 may be set as described above so that, when the lateral distance is at its maximum value within the adjustable range, the entire gamma-ray detector 12 is hidden by the gamma-ray shielding section 14 from any viewpoint (position) in the deceleration section 13a.

[0056] (Dimensions of the gamma-ray detector) The lateral dimensions of the gamma-ray detector 12 may be smaller than the lateral dimensions of the neutron shielding section 13, the gamma-ray shielding section 14, the first neutron absorption section 15, and the lateral absorption section 16b. Similarly, the forward dimensions of the gamma-ray detector 12 may be smaller than the forward dimensions of the neutron shielding section 13, the gamma-ray shielding section 14, the first neutron absorption section 15, and the lateral absorption section 16b. In this case, when viewed from the side, the gamma-ray detector 12 may be positioned such that the whole or a part of it is included within the ranges of the neutron shielding section 13, the gamma-ray shielding section 14, the first neutron absorption section 15, and the lateral absorption section 16b. In this case, the rear portion of the gamma-ray detector 12 may be located behind the neutron shielding section 13.

[0057] (Connection of parts) The gamma-ray detector 12, the neutron shielding unit 13, the gamma-ray shielding unit 14, and the first and second neutron absorption units 15 and 16 may be integrated with each other by being connected directly or via other members. In addition, the non-destructive testing device 10 may be configured with a plurality of units that are detachable from each other, as in the second embodiment described later.

[0058] (Configuration for processing detection signals from a gamma-ray detector) In addition to the above configuration, the non-destructive testing apparatus 10 may further include a detection amount measuring device 21 and a data processing device 23 for processing detection signals.

[0059] The detection amount measuring device 21 receives each detection signal generated by the gamma-ray detector 12. In this case, each detection signal generated and output by the gamma-ray detector 12 may be input to the detection amount measuring device 21 via the preamplifier 22. As a result, each detection signal amplified by the preamplifier 22 is input to the detection amount measuring device 21.

[0060] The detection amount measuring device 21 generates detection data to indicate the amount of gamma rays detected (number of detections) at each energy of gamma rays, based on each detection signal from the gamma-ray detector 12 (for example, the pulse height of each detection signal). The detection data may be pulse height spectral data representing the number of detection signals at each pulse height of the detection signal. The detection data may be obtained by performing an inspection over a predetermined measurement time (for example, 10 minutes or more). A device (not shown) for applying an operating voltage to the gamma-ray detector 12 may be integrated with the detection amount measuring device 21 or provided separately from the detection amount measuring device 21.

[0061] The data processing device 23 receives detection data from the detection amount measuring device 21. The data processing device 23 processes the detection data for inspection of the object to be inspected 1. The data processing device 23 may also perform a process to generate a gamma ray energy spectrum from the pulse height spectral data, which is the detection data. The energy spectrum is data that represents the amount of gamma rays detected for each energy of gamma rays. Based on the above detection data (or the above energy spectrum), the data processing device 23 may determine the presence or absence of the target component in the object to be inspected 1, or it may determine the depth at which the target component (e.g., chlorine) exists in the object to be inspected 1, or it may determine the concentration of the target component at that depth or a specific depth. The target component is a component that emits gamma rays with a specific energy unique to the target component when it reacts with neutrons incident on the object to be inspected 1. Note that the processing method by which the data processing device 23 determines the depth at which the target component exists and the concentration of the target component at that depth or a specific depth based on the energy spectrum is described in Patent Document 1 or 2, so its explanation is omitted here.

[0062] (Configuration to eliminate detection of Compton-scattered gamma rays) In addition to the above configuration, the non-destructive testing apparatus 10 may further include a sub-detector 24 in order to obtain detection data in which the background of Compton-scattered gamma rays is reduced in the gamma-ray detector 12. The sub-detector 24 surrounds the gamma-ray detector 12. Note that this surrounding area does not have to be the entire area around the gamma-ray detector 12, but may be the area excluding the gamma-ray entry region described later.

[0063] Here, when viewed from the front end of the gamma-ray detector 12, the region R located diagonally forward, tilted from the front towards the neutron shielding section 13 (for example, region R in Figure 1A) is defined as the gamma-ray entry region from the object under inspection 1. The sub-detector 24 covers the gamma-ray detector 12 from around it, excluding at least the entry region R. That is, the sub-detector 24 is positioned to surround the central axis passing through the gamma-ray detector 12 in the forward direction, but it does not exist in the entry region R. Therefore, gamma rays traveling from inside the object under inspection 1 through the entry region R to the gamma-ray detector 12 enter the gamma-ray detector 12 without entering the sub-detector 24.

[0064] Furthermore, a secondary detector 24 may also be provided directly behind the gamma-ray detector 12 in the opposite direction to the forward direction. A secondary detector 24 does not need to be provided in front of the gamma-ray detector 12 in the forward direction. However, a secondary detector 24 may also be provided in front of (front of) the gamma-ray detector 12.

[0065] When gamma rays are incident on the sub-detector 24, the sub-detector 24 inputs the incident signal to the detection amount measuring device 21. Also, as described above, when gamma rays are incident on the gamma-ray detector 12, the gamma-ray detector 12 inputs the detection signal described above to the detection amount measuring device 21. If the detection signal and the incident signal are input to the detection amount measuring device 21 simultaneously, the detection signal is discarded and not reflected in the detection data. As a result, the detection of gamma rays that were incident on the gamma-ray detector 12 but underwent Compton scattering and were incident on the sub-detector 24 outside the gamma-ray detector 12 is not reflected in the detection data. This increases the accuracy of nuclide identification based on the detection data. Note that the processing of the detection amount measuring device 21 may be performed by the data processing device 23. That is, the detection amount measuring device 21 may be incorporated into the data processing device 23.

[0066] Furthermore, a person may operate an appropriate control unit (such as a button or touch panel) to set the mode of the detection amount measuring device 21 to either the following first mode or second mode. When the detection amount measuring device 21 is set to the first mode, if a detection signal and an incident signal are input to it simultaneously, the detection signal will not be reflected in the detection data. When the detection amount measuring device 21 is set to the second mode, even if a detection signal and an incident signal are input to it simultaneously, the detection signal will be reflected in the detection data.

[0067] The secondary detector 24 may be a scintillator formed of bismuth germanate (BGO), but is not limited to this as long as it is configured to detect incident gamma rays. The secondary detector 24 may be formed of a material that shields against external gamma rays (e.g., BGO). This allows the secondary detector 24 to also function to suppress background gamma rays (e.g., gamma rays generated in the deceleration unit 13a) from entering the gamma-ray detector 12.

[0068] (Weight of Nondestructive Testing Equipment) The main structure consists of a neutron source 11, a gamma-ray detector (germanium semiconductor detector) 12, a deceleration unit 13a, a reflection unit 13b, a gamma-ray shielding unit 14, a first neutron absorption unit 15, and a second neutron absorption unit 16. The weight of this main structure may be between 10 kg and less than 20 kg (or 15 kg and more), as in the embodiment described later, but is not limited to this range. For example, it may be between 50 kg and less than 100 kg, between 30 kg and less than 50 kg, or between 20 kg and less than 30 kg. In this case, the second neutron absorption unit 16 constituting the main structure may be a combination of a forward absorption unit 16a and a side absorption unit 16b, or if the forward absorption unit 16a is omitted, only the side absorption unit 16b may be used.

[0069] Furthermore, since the weight of the sub-detector 24 is, for example, about 20 kg, and the weight of the dewar 17 is, for example, about 7 kg to 8 kg, the total weight of the main structural components and these can be kept to, for example, less than 50 kg.

[0070] (Configuration supporting each component of the non-destructive testing device) Figure 2 is a more detailed view of the non-destructive testing device 10 in Figure 1A. In the example of Figure 2, the forward direction mentioned above is the vertically upward direction, and the surface 1a of the object to be inspected 1 is the lower surface of the object to be inspected 1.

[0071] As shown in Figure 2, the non-destructive testing apparatus 10 may further include a support 31 in addition to the configuration described above. The support 31 supports the neutron shielding section 13, the gamma-ray detector 12, the gamma-ray shielding section 14, and the first and second neutron absorption sections 15, 16, etc. The gamma-ray detector 12, the neutron shielding section 13, the gamma-ray shielding section 14, and the first and second neutron absorption sections 15, 16 may be integrated with each other by being attached (for example, fixed) to the support 31. The detection amount measuring device 21 and the data processing device 23 may also be supported by the support 31, as shown in Figure 2.

[0072] (Position adjustment mechanism) As shown in Figure 2, the non-destructive testing apparatus 10 may further include a base 32 and a position adjustment mechanism 33 in addition to the configuration described above.

[0073] The base 32 supports the gamma-ray detector 12, the neutron shielding section 13, the gamma-ray shielding section 14, and the first and second neutron absorption sections 15, 16, etc., by supporting the support 31 via the position adjustment mechanism 33. In the example of Figure 2, the base 32 is installed on a platform 34, which is, for example, coupled to the tip of a multi-jointed movable boom provided on a vehicle, and may be moved directly below the underside 1a of the object to be inspected 1 (e.g., a bridge) by the operation of the movable boom. The platform 34 may also be designed to accommodate a person in addition to the non-destructive testing device 10.

[0074] The position adjustment mechanism 33 can adjust the position of the support 31 relative to the base 32 in a direction parallel to the forward direction. As a result, the position adjustment mechanism 33 can adjust the positions of the gamma-ray detector 12, the neutron shielding section 13, the gamma-ray shielding section 14, and the first and second neutron absorption sections 15 and 16 relative to the base 32, thereby adjusting them relative to the surface 1a of the object to be inspected 1.

[0075] When the forward direction is vertically upward, the position adjustment mechanism 33 may be a jack that extends and retracts vertically, as shown in Figure 2. The extension and retraction of the jack may be operated by an operating unit. When a person operates the operating unit (not shown), the jack extends or retracts by an amount corresponding to the operation. The jack may be a hydraulic jack or an electric jack, and the operating unit may be a pedal, lever, button, etc. The operating unit may be provided on the jack, or it may be provided separately from the jack and the jack may be operated wirelessly.

[0076] Furthermore, the position adjustment mechanism 33 is not limited to a jack and may have other configurations, as long as it can adjust the position of the support 31 relative to the base 32 by moving the support 31 in a direction parallel to the forward direction. For example, the position adjustment mechanism 33 may be composed of an appropriate linear actuator that moves the support 31 in a direction parallel to the forward direction. Also, in this application, the forward direction does not have to be vertically upward, but may be horizontal, oblique to the horizontal, or vertically downward.

[0077] However, the position adjustment mechanism 33 is not required. In this case, the non-destructive testing device 10 may be installed on the base 32 without the position adjustment mechanism 33.

[0078] (Example) In the non-destructive testing apparatus 10 of the example, 3.7 MBq of californium is used as the neutron source 11. ２５２ Cf) was used. In the non-destructive testing apparatus 10 of the embodiment, the deceleration section 13a was made of polyethylene, the reflecting section 13b was made of graphite, the gamma-ray shielding section 14 was made of lead, the first neutron absorption section 15 was made of rubber containing boron carbide, and the second neutron absorption section 16 was made of lithium fluoride.

[0079] Figures 3A and 3B correspond to Figures 1A and 1B, respectively, and show the dimensions of each part of the non-destructive testing apparatus 10 of the embodiment. As shown in Figures 3A and 3B, the non-destructive testing apparatus 10 of the embodiment is configured to be compact with a lateral dimension of approximately 450 mm. In addition, in the non-destructive testing apparatus 10 of the embodiment, the sum of the weights of the neutron source 11, gamma-ray detector 12, neutron shielding unit 13, gamma-ray shielding unit 14, first neutron absorption unit 15, second neutron absorption unit 16, dewar 17, and cold finger 18 is less than 30 kg, and the sum plus the weight of the sub-detector 24 is less than 50 kg.

[0080] Figure 3C shows a configuration in which, unlike this embodiment, the reflective portion 13b covers the entire periphery of the deceleration unit 13a, including the predetermined region described above. In Figure 3C, the other configurations are the same as in Figure 3A. Compared to Figure 3C, in this embodiment, as shown in Figures 3A and 3B, the reflective portion 13b does not exist in the predetermined region on the gamma-ray detector 12 side as viewed from the deceleration unit 13a. Therefore, the lateral distance between the neutron source 11 and the gamma-ray detector 12 can be shortened by that amount (for example, by the lateral dimension of the predetermined region). For example, in the lateral direction, the distance from the center of the neutron source 11 to the center of the gamma-ray detector 12 is 228.5 mm in Figure 3C, but approximately 180 mm in Figure 3A. Therefore, in the embodiment of Figure 3A, the lateral distance between the neutron source 11 and the gamma-ray detector 12 can be reduced by approximately 50 mm.

[0081] As a result, the detection sensitivity of the target component by the non-destructive testing device 10 in the embodiment of Figure 3A was nearly doubled compared to the case of Figure 3C. That is, in both Figure 3A and Figure 3C, in the inspection target object 1, which is a concrete structure, the concentration was 3.0 kg / m³ at a depth of 0 cm to 3 cm from the surface 1a. ３ When chlorine is present as the target component, the presence of chlorine and chlorine ( ３５ The concentration of Cl was detectable, and the detection sensitivity was nearly twice as high in the case of Figure 3A compared to the case of Figure 3C.

[0082] (Effects of the First Embodiment) Since the neutron source 11 spontaneously generates and emits neutrons, unlike neutron sources that generate neutrons by colliding a charged particle beam with a target, large-scale equipment or accelerators for generating charged particle beams are not required. Therefore, the non-destructive testing device 10 can be made smaller and lighter to facilitate transport and placement.

[0083] Furthermore, since the neutron shielding section 13 that covers the neutron source from at least its surroundings and the gamma-ray detector 12 are arranged side by side, the neutron source 11 surrounded by the neutron shielding section 13 and the gamma-ray detector 12 can both be placed near the surface 1a of the object to be inspected 1. Therefore, neutrons from the neutron source 11 can be efficiently incident onto the object to be inspected 1, and gamma rays generated by these neutrons within the object to be inspected 1 can be efficiently detected. For this reason, compared to neutron sources that generate neutrons by colliding charged particle beams with a target using large-scale equipment or accelerators that are difficult to transport and position, a neutron source with a small amount of emitted neutrons (for example, the above-mentioned) is preferable. ２５２ Even with an RI neutron source such as Cf, or a neutron generating tube, a sufficient amount of gamma rays can be detected. Therefore, based on the detected gamma rays, it is possible to determine the presence, depth, or concentration of the target component within the object being inspected 1.

[0084] In this embodiment, in particular, the reflective section 13b is not provided in the predetermined region on the gamma-ray detector 12 side as viewed from the deceleration section 13a, so the lateral distance between the neutron source 11 and the gamma-ray detector 12 can be shortened accordingly. This makes it possible to further improve the detection sensitivity of the target component by the non-destructive testing device 10 (for example, by about twice). In addition, since the reflective section 13b is not provided in the predetermined region, the non-destructive testing device 10 can be made lighter.

[0085] [Second Embodiment] The non-destructive testing apparatus 10 according to the second embodiment will be described below. In the second embodiment, matters not described below may be the same as in the first embodiment. For example, in the second embodiment, the configuration (material, shape, dimensions, etc.) of the neutron source 11, gamma-ray detector 12, neutron shielding unit 13, gamma-ray shielding unit 14, and the first and second neutron absorption units 15, 16 may be the same as in the first embodiment.

[0086] Figure 4A shows an example of the overall configuration of the non-destructive testing apparatus 10 according to the second embodiment. The non-destructive testing apparatus 10 according to the second embodiment comprises a radiation source unit U1, a main detector unit U2, and a sub-detector unit U3 that are detachable from one another. The radiation source unit U1, the main detector unit U2, and the sub-detector unit U3 may be detachable from one another via a support structure 84 (e.g., a support frame) described later. This allows the non-destructive testing apparatus 10 to be assembled.

[0087] (Radiation Source Unit) Figures 5A and 5B show the radiation source unit U1. Figure 5A shows the radiation source unit U1 in Figure 4A, and Figure 5B is a view taken along the line 5B-5B in Figure 5A. The radiation source unit U1 is formed by attaching multiple components to each other and integrating them. These multiple components include a neutron source 11 and a neutron shielding section 13. These multiple components may also include a first neutron absorption section 15. Furthermore, these multiple components may also include a gamma-ray shielding section 14. For convenience, Figures 5A and 5B show the orientation (lateral direction, etc.) of the non-destructive testing device 10 in its assembled state (i.e., the state during testing) (the same applies to the other figures).

[0088] The above-mentioned multiple components of the radiation source unit U1 have a first base 81 that is detachable from the support structure 84. The other components of the radiation source unit U1 (such as the neutron shielding section 13) may be integrated into the first base 81. The first base 81 is detachable from the first mounting section 84a of the support structure 84 by a detachment device 85, which will be described later.

[0089] (Main Detector Unit) Figures 6A and 6B show the main detector unit U2. Figure 6A shows the main detector unit U2 in Figure 4A, and Figure 6B is a view along the line 6B-6B in Figure 6A. The main detector unit U2 is formed by attaching multiple components to each other and integrating them. These multiple components include a gamma-ray detector 12. When the gamma-ray detector 12 is the germanium semiconductor detector described above, as shown in Figure 6A, the multiple components of the main detector unit U2 may further include the dewar 17, cold finger 18, and container 12v described above, or they may include an electric cooler for electrically cooling the germanium semiconductor detector 12. Furthermore, the multiple components of the main detector unit U2 may further include the preamplifier 22 described above.

[0090] The above-mentioned multiple components of the main detector unit U2 have a second base 82 that is detachable from the support structure 84. Other components of the main detector unit U2 may be integrated into the second base 82. The second base 82 is detachable from the second mounting portion 84b of the support structure 84 by a detachable device 85, which will be described later. The second mounting portion 84b may be slidable in the forward and backward directions, as will be described later.

[0091] Multiple support legs 82s are attached to the outer surface of the second base 82. The multiple support legs 82s are attached to the outer surface in a two-dimensionally distributed manner. This allows the main detector unit U2 to be placed on a horizontal surface (e.g., the floor) so that it is supported by the multiple support legs 82s, and makes it easier to handle the main detector unit U2. The length of each support leg 82s (length in the direction perpendicular to the outer surface) is longer than the length to which the attachment / detachment device 85 (movable part 85c, described later in the example of Figure 6B) protrudes from the outer surface of the second base 82.

[0092] (Sub-detector unit) Figures 7A and 7B show the sub-detector unit U3. Figure 7A shows the sub-detector unit U3 in Figure 4A, and Figure 7B is a view taken along the line 7B-7B in Figure 7A. The sub-detector unit U3 is formed by integrating multiple components that are attached to each other. These multiple components include a sub-detector 24. These multiple components may further include a second neutron absorption unit 16.

[0093] The above-mentioned multiple components of the sub-detector unit U3 have a third base 83 that is detachable from the support structure 84. The other components of the sub-detector unit U3 (such as the sub-detector 24) may be integrated into the third base 83. The third base 83 is detachable from the third mounting portion 84c of the support structure 84 by a detachable device 85, which will be described later. The third base 83 also has through holes 83h formed therein that allow the gamma-ray detector 12 (in the example of Figure 7A, the germanium semiconductor detector 12 and the container 12v) to pass through in the forward and backward directions.

[0094] (Support Structure) Figures 8A and 8B show the support structure 84 in Figures 4A and 4B in more detail, respectively. The support structure 84 has a first mounting portion 84a from which the radiation source unit U1 can be attached and detached, a second mounting portion 84b from which the main detector unit U2 can be attached and detached, and a third mounting portion 84c from which the sub-detector unit U3 can be attached and detached. Therefore, the radiation source unit U1, the main detector unit U2, and the sub-detector unit U3 can be attached and detached from each other via the support structure 84. The first to third mounting portions 84a to 84c may each be plate-shaped as shown in each figure, but are not limited to this. Note that in Figure 8A, the attachment / detachment device 85 (configuration on the movable portion 85c side) provided on the third mounting portion 84c is not shown.

[0095] As will be described later, the support structure 84 (the third mounting portion 84c in the example of Figure 8A) has a through-hole 84h through which the gamma-ray detector 12 (germanium semiconductor detector) can pass. The main detector unit U2, while attached to the second mounting portion 84b, is slidable between the position in Figure 4A and the position in Figure 4B, as will be described later.

[0096] Furthermore, the support structure 84 may be a support frame as shown in Figure 8A. The support frame 84 has a plurality of column members 84d and plate-shaped first to third mounting portions 84a to 84c connected to these column members 84d. Note that the plurality of column members 84d (three in Figure 8A) may be arranged in pairs, with two pairs spaced apart in the vertical direction.

[0097] Furthermore, the support structure 84 may have a plate-shaped mounting section 84e on which the detection amount measuring device 21 and the data processing device 23 are placed. Note that in Figure 8A, the forward direction may be the vertical direction.

[0098] (Attachment / Detachment Devices) The attachment and detachment of the radiation source unit U1 to the first mounting portion 84a, the attachment and detachment of the main detector unit U2 to the second mounting portion 84b, and the attachment and detachment of the sub-detector unit U3 to the third mounting portion 84c may be performed by attachment / detachment devices 85. These attachment / detachment devices 85 may be components of the non-destructive testing apparatus 10.

[0099] <Detachable device enabling attachment and detachment of the first base and the first mounting part> Figures 9A and 9B are cross-sectional views showing a detachable device 85 that enables attachment and detachment of the first base 81 and the first mounting part 84a. Figure 9A shows the state in which the first base 81 and the first mounting part 84a are attached to each other (hereinafter also simply referred to as the attached state), and Figure 9B shows the state in which the first base 81 and the first mounting part 84a are separated from each other. The detachable device 85 is capable of holding the first base 81 and the first mounting part 84a in the state in which they are attached to each other, and from this state, the first base 81 and the first mounting part 84a can be detached from each other.

[0100] As shown in Figures 9A and 9B, the first base 81 and the first mounting portion 84a have through holes 85h1 and 85h2 that are aligned with each other in the attachment and detachment direction for attaching the attachment and detachment device 85.

[0101] The attachment / detachment device 85 includes a first member 85a, a second member 85b, a movable part 85c, and a spring 85d. The first member 85a is attached (for example, fixed) to the first base 81 on the side opposite to the first mounting part 84a when installed. The second member 85b is attached (for example, fixed) to the first mounting part 84a on the side opposite to the first base 81 when installed. The movable part 85c, together with the engagement part 85c1 provided at its tip (described later), is rotatably attached to the second member 85b around its axis Ax between the state in Figure 8A and the state in Figure 8B. The spring 85d biases the movable part 85c toward its base end (downward in Figure 9A). The spring 85d may be, for example, a coil spring. The spring 85d is compressed, for example, between the surface of the first mounting portion 84a opposite to the first base 81 and the enlarged diameter portion 85c3 of the movable portion 85c, thereby biasing the movable portion 85c toward its base end.

[0102] The tip of the movable part 85c is provided with an elongated engaging portion 85c1 that extends in a direction perpendicular to the axis Ax of the movable part 85c (the left-right direction in Figure 9A, i.e., the direction perpendicular to the plane of the paper in Figure 9B). The first member 85a has an elongated hole 85a1 formed therein so as to align with the engaging portion 85c1 when attaching and detaching the first base 81 and the first mounting portion 84a (in a direction perpendicular to the plane of the paper in Figures 9A and 9B).

[0103] To attach the first base 81 and the first mounting portion 84a to each other from the state shown in Figure 9B, the engaging portion 85c1 and the elongated hole 85a1 are aligned in the direction of axis Ax so that their orientations are the same, and in this state (the state shown in Figure 9B), the first base 81 is moved in the direction of arrow X in Figure 9B. This causes the engaging portion 85c1 to pass through the elongated hole 85a1. Next, while pushing the movable portion 85c toward the first member 85a against the biasing force of the spring 85d, the movable portion 85c is rotated (for example, by 90 degrees) so that the orientation of the engaging portion is as shown in Figure 9A. This operation may be performed by manually operating the operating portion 85c2 provided at the base end of the movable portion 85c. Next, when the hand is released from the operating part 85c2, the biasing force of the spring 85d causes the engaging part 85c1 to be pressed against the surface forming the opening of the elongated hole 85a1 in the first member 85a (the opening opposite the first base 81) and locked in place, resulting in the state shown in Figure 9A. As a result, the first base 81 is attached to and held in place by the first mounting part 84a.

[0104] By performing the reverse procedure of this procedure, the first base 81 and the first mounting portion 84a can be removed from each other from the state shown in Figure 9A.

[0105] Multiple sets of such attachment / detachment devices 85, through holes 85h1 in the first base 81, and through holes 85h2 in the first mounting portion 84a may be provided at locations spaced apart from each other, with each set forming one such combination. Alternatively, the first member 85a may be attached to the first mounting portion 84a, and the second member 85b may be attached to the first base 81.

[0106] Furthermore, the attachment / detachment device 85 can be any device that can hold the first base 81 and the first mounting portion 84a in a state where they are attached to each other, and that can detach the first base 81 and the first mounting portion 84a from this state. For example, the attachment / detachment device 85 may be a bolt and a nut that pass through the above-mentioned through holes 85h1 and 85h2. In this case, the first base 81 and the first mounting portion 84a may be attached to each other by sandwiching them between the head of the bolt and the nut screwed onto the tip of the bolt. Alternatively, the attachment / detachment device 85 may be, for example, another suitable known device.

[0107] <Detachable device enabling attachment and detachment of the second base and the second mounting portion> The above-described detachable device 85 that enables attachment and detachment of the first base 81 and the first mounting portion 84a also applies to a detachable device that enables attachment and detachment of the second base 82 and the second mounting portion 84b. In this case, the first base 81 and the first mounting portion 84a are read as the second base 82 and the second mounting portion 84b in the above description, and in Figures 9A and 9B, reference numerals 81 and 84a are replaced with reference numerals 82 and 84b, respectively.

[0108] <Detachable device enabling attachment and detachment of the third base and the third mounting portion> Similarly, the above-described detachable device 85 that enables attachment and detachment of the first base 81 and the first mounting portion 84a also applies to a detachable device that enables attachment and detachment of the third base 83 and the third mounting portion 84c. In this case, the first base 81 and the first mounting portion 84a are read as the third base 83 and the third mounting portion 84c in the above description, and reference numerals 81 and 84a are replaced with reference numerals 83 and 84c, respectively, in Figures 9A and 9B.

[0109] (Guide mechanism for main detector unit) The configuration for making the second mounting portion 84b to which the main detector unit U2 is attached slidable will be explained with reference to the configuration examples in Figures 10A and 10B. Figures 10A and 10B are views from the left side in Figure 8A, and mainly show the configuration for making the main detector unit U2 slidable. Note that in Figures 10A and 10, only a part is shown in cross-section for convenience. Note that in Figure 8A, the attachment / detachment device 85 (configuration on the movable part 85c side) provided on the third mounting portion 84c is not shown.

[0110] The support structure 84 includes a guide mechanism 84f that allows the second mounting portion 84b to slide in a predetermined sliding direction relative to the third mounting portion 84c. That is, the guide mechanism 84f guides the second mounting portion 84b to slide in the sliding direction. The guide mechanism 84f also restricts the movement of the second mounting portion 84b in directions perpendicular to the sliding direction. In this embodiment, the sliding directions are the forward direction (for example, vertically upward) and the backward direction.

[0111] With the main detector unit U2 attached to the second mounting portion 84b (for example, as shown in Figure 10B), the gamma-ray detector 12 can be positioned in the area surrounded by the sub-detectors 24 by sliding the second mounting portion 84b (for example, the gamma-ray detector 12 can be positioned as shown in Figures 4A and 10A).

[0112] Furthermore, a through hole 84h is formed in the third mounting portion 84c of the support structure 84. Also, a through hole 83h is formed in the third base 83. With the main detector unit U2 attached to the second mounting portion 84b, the gamma-ray detector 12 (and container 12v) of the main detector unit U2 can be placed in the region surrounded by the sub-detectors 24 by sliding the second mounting portion 84b forward so that it passes through the through hole 84h of the third mounting portion 84c (and the through hole 83h of the third base 83).

[0113] For example, the main detector unit U2 can be assembled to the support structure 84 by following the steps S1 to S3. First, in step S1, with the second mounting portion 84b positioned at the rear end (downward vertically) within its slidable range, the second base 82 is attached to the second mounting portion 84b by the attachment / detachment device 85, thereby attaching the main detector unit U2 to the second mounting portion 84b as shown in Figure 10B. At this time, the main detector unit U2 may be supported from below by the structural part of the support structure 84. Next, in step S2, the main detector unit U2 and the second mounting portion 84b are slid together forward (upward vertically), for example, manually. As a result, the gamma-ray detector 12 (and its container 12v) passes through the through hole 84h of the third mounting portion 84c and is positioned in the area surrounded by the sub-detector 24. If the sub-detector unit U3 is already attached to the support structure 84 at this time, the gamma-ray detector 12 (and its container 12v) passes through the through hole 84h of the third mounting portion 84c and the through hole 83h of the third base 83. In this state, in step S3, the main detector unit U2 or the second mounting portion 84b may be supported by an appropriate locking mechanism to prevent the second mounting portion 84b from moving downward. This locking mechanism may be provided on the support structure 84 so as to be movable between a position that does not interfere with the sliding movement of the main detector unit U2 and the second mounting portion 84b and a position that supports the main detector unit U2 or the second mounting portion 84b.

[0114] In the examples shown in Figures 10A and 10B, the guide mechanism 84f is a rail extending in the forward direction. The rail 84f guides the second mounting portion 84b in the forward and backward directions. In the examples shown in Figures 10A and 10B, two rails 84f are provided. Also in the examples shown in Figures 10A and 10B, a slider 84bs is provided on the second mounting portion 84b, and the slider 84bs is attached to the rail 84f so as to be movable in the sliding direction. However, the guide mechanism 84bs is not limited to a rail and may have other configurations (for example, a guide groove).

[0115] Furthermore, as shown in Figure 10A, a stopper 84g may be provided on the second mounting portion 84b. The stopper 84g abuts against a predetermined stationary portion of the support structure 84 (the lower surface of the third mounting portion 84c in the example of Figure 10A) in step S2 described above, so as to prevent the second mounting portion 84b from moving further forward from the state shown in Figure 10A. This prevents the upper end of the container 12v of the gamma-ray detector 12 from colliding with and damaging the second neutron absorption portion 16 of the sub-detector unit U3 if the sub-detector unit U3 is already attached to the support structure 84 before step S2.

[0116] (Effects of the second embodiment) According to the second embodiment, the radiation source unit U1, the main detector unit U2, and the sub-detector unit U3 that constitute the non-destructive testing apparatus 10 can be transported separately to the inspection site. This makes it easier to transport the non-destructive testing apparatus 10.

[0117] Furthermore, the non-destructive testing device 10 can be easily assembled on-site by attaching the radiation source unit U1, the main detector unit U2, and the sub-detector unit U3 to each other.

[0118] Furthermore, the support structure 84 can be transported to the inspection site separately from the radiation source unit U1, the main detector unit U2, and the sub-detector unit U3 that constitute the non-destructive testing apparatus 10. The non-destructive testing apparatus 10 can be assembled by attaching the radiation source unit U1, the main detector unit U2, and the sub-detector unit U3 to such a support structure 84. Therefore, the assembly of the non-destructive testing apparatus becomes even easier.

[0119] Furthermore, since the second mounting portion 84b to which the main detector unit U2 is attached is slidable by the guide mechanism 84f, it becomes easier to position the gamma-ray detector 12 of the main detector unit U2 in the area surrounded by the sub-detectors 24. At this time, since a through hole 84h through which the gamma-ray detector 12 (and its container 12v) can pass is formed in the third mounting portion 84c, the gamma-ray detector 12 can be positioned in the area surrounded by the sub-detectors 24 by sliding the second mounting portion 84b so that it passes through the through hole 84h.

[0120] The present invention is not limited to the embodiments described above, and it goes without saying that various modifications and improvements can be made within the scope of the technical concept of the present invention.

[0121] [Configurations A and B] For example, in each of the first and second embodiments described above, one or both of the following configurations A and B may be adopted.

[0122] (Configuration A) Figure 11 is a block diagram showing a configuration that eliminates the detection of Compton-scattered gamma rays.

[0123] When gamma rays are incident on the gamma-ray detector 12, the gamma-ray detector 12 outputs an analog detection signal to the detection amount measuring device 21. Similarly, when gamma rays are incident on the sub-detector 24, the sub-detector 24 outputs an analog incident signal to the rejection signal generation unit 86, which will be described later.

[0124] As shown in Figure 11, the non-destructive testing apparatus 10 comprises the detection amount measuring device 21, the rejection signal generation unit 86, and the data processing device 23. The detection amount measuring device 21 and the rejection signal generation unit 86 are composed of hardware. The detection amount measuring device 21 and the rejection signal generation unit 86 may or may not include software. On the other hand, the data processing device 23 is a computer that operates using software. That is, the data processing device 23 is composed of software.

[0125] As described above, the detection amount measuring device 21 generates detection data representing the amount of gamma rays detected at each energy of gamma rays, based on each analog detection signal (the peak value of each detection signal) from the gamma-ray detector 12. This detection data may be, for example, peak value spectral data representing the number of detection signals for each peak value of the detection signal. The detection data generated by the detection amount measuring device 21 may be digital data that can be processed by a computer.

[0126] When the rejection signal generation unit 86 receives an incident signal from the sub-detector 24, it outputs a rejection signal to the detection amount measuring device 21 indicating that it rejects the use of the detection signal. This rejection signal may be a digital signal. The detection amount measuring device 21 is configured or set up so that, if a detection signal and a rejection signal are input simultaneously, the detection signal is not used to generate detection data.

[0127] The detection amount measuring device 21 outputs the generated detection data to the data processing device 23. The data processing device 23 may process the detection data using software to determine the depth at which the target component (e.g., chlorine) exists in the object to be inspected 1, or to determine the concentration of the target component at that depth or a specific depth. The processing by the data processing device may include the process of generating energy spectrum data representing the detected amount of gamma rays for each energy of gamma rays from the above-mentioned peak value spectrum data.

[0128] In the example shown in Figure 11, the detection amount measuring device 21 includes an amplifier 21a that amplifies the detection signal from the preamplifier 22, and a data generation unit 21b that generates detection data based on the detection signal amplified by the amplifier 21a.

[0129] In the example shown in Figure 11, the rejection signal generation unit 86 includes an amplifier 86a that amplifies the incident signal from the sub-detector 24, and a signal output unit 86b that generates and outputs the aforementioned rejection signal based on the incident signal amplified by the amplifier 86a.

[0130] Furthermore, in the example shown in Figure 11, the incident signal described above is generated and output by the signal output unit 24a of the sub-detector 24 (MPPC 24a1 (Multi-Pixel Photon Counter) and readout board 24a2). In the case of the second embodiment, the signal output unit 24a may be pre-attached to the sub-detector unit U3 (for example, the third base 83) (for example, it may be fixed in place). This facilitates the assembly of the non-destructive testing apparatus 10.

[0131] According to Configuration Example A, as described above, the hardware detection amount measuring device 21 and rejection signal generation unit 86 and the software data processing device 23 are configured separately from each other. Therefore, for example, at the inspection site, it is only necessary to connect the data processing device 23, which acts as a computer (e.g., a portable PC such as a tablet PC), to the detection amount measuring device 21 with a digital signal cable (e.g., a LAN cable). Furthermore, the detection amount measuring device 21 can be connected to the signal output unit 24a of the sub-detector 24 and the preamplifier 22, respectively, with analog signal cables (at this time, the detection amount measuring device 21 may be connected to the signal output unit 24a of the sub-detector 24 via the rejection signal generation unit 86, the rejection signal generation unit 86 and the signal output unit 24a may be connected with an analog signal cable, and the rejection signal generation unit 86 may be incorporated into the detection amount measuring device 21). Consequently, the number of cables used for connection is small, and the configuration for processing detection signals can be easily assembled at the inspection site. Note that the rejection signal generation unit 86 may be separate from the detection amount measuring device 21. Furthermore, the sub-detector 24 is integrated with the gamma-ray detector 12 so as to surround it from all sides (see, for example, Figures 1C and 7B). That is, the sub-detector 24 extends continuously in the circumferential direction of the gamma-ray detector 12 (for example, around the gamma-ray detector 12) so as to surround the gamma-ray detector 12 when viewed from the front. This reduces the number of cables connecting the sub-detector 24 and the rejection signal generation unit 86 (for example, to one). For example, no matter where gamma rays are incident on the sub-detector 24, the sub-detector 24 outputs the incident signal resulting from that incident to the rejection signal generation unit 86 through that single cable.

[0132] (Configuration B) The non-destructive testing apparatus 10 may be equipped with a waterproof cover 87. Figure 12 shows an example of a waterproof cover 87. This waterproof cover 87 covers the main body of the non-destructive testing apparatus 10 from above (i.e., in the front direction) and around it (i.e., in each direction perpendicular to the front direction). In this way, the waterproof cover 87 prevents rainwater from entering the main body located in the internal space of the waterproof cover 87. The main body may include the above-described components of the non-destructive testing apparatus 10. In the second embodiment, the main body includes a radiation source unit U1, a main detector unit U2, a sub-detector unit U3, and a support structure 84 (support frame) mounted to each other.

[0133] Figure 13A is a perspective view showing only the waterproof cover 87 of Figure 12, and Figure 13B is an exploded perspective view of the waterproof cover 87 of Figure 13A.

[0134] As shown in Figures 12 to 13B, the waterproof cover 87 may have an upper cover 88 and a peripheral cover 89. The upper cover 88 covers the main body from above. The peripheral cover 89 covers the main body from its periphery. The peripheral cover 89 forms an internal space that penetrates vertically to the inside.

[0135] The surrounding cover 89 may be composed of multiple plate-like members 89a (e.g., panels) as shown in Figures 12 to 13B (four in the example shown in these figures). In the second embodiment, these plate-like members 89a may be attached to the support structure 84 (e.g., column member 84d) by appropriate means to detachably form the surrounding cover 89. Alternatively, the surrounding cover 89 may be formed integrally beforehand.

[0136] The surrounding cover 89 may be lowered from above the main body so that the main body fits into the internal space of the surrounding cover 89, thereby covering the main body from all sides. In this state, the lower end of the surrounding cover 89 may be supported on the surface on which the main body (support structure 84) is placed.

[0137] After installing the surrounding cover 89 to cover the main body from all sides, the upper cover 88 is attached to the surrounding cover 89 so as to cover the upper opening 89b of the internal space of the surrounding cover 89, as shown in Figures 12 and 13A. The upper cover 88 may have an upper part 88a that covers the upper opening 89b of the internal space of the surrounding cover 89 from above, and an outer peripheral part 88b that extends downward from the outer peripheral edge of the upper part 88a and covers the upper end of the surrounding cover 89 from all sides. The upper end of the surrounding cover 89 restricts the movement of the outer peripheral part 88b in the horizontal direction.

[0138] According to configuration B, the waterproof cover 87 can cover the main body of the non-destructive testing device 10, so that even in rainy weather, the inspection can be performed without wetting the main body with rainwater.

[0139] Furthermore, since the waterproof cover 87 is composed of an upper cover 88 and a surrounding cover 89, which are separate components, the waterproof cover 87 can be easily installed on the main body using the procedure described above.

[0140] Furthermore, when the waterproof cover 87 covers the main body (as shown in Figures 12 and 13A), the outer periphery 88b of the upper cover 88 covers the upper end of the surrounding cover 89 from the outside, thus more reliably preventing rainwater from entering the internal space of the surrounding cover 89. In addition, the upper end of the surrounding cover 89 restricts the horizontal movement of the outer periphery 88b of the upper cover 88. That is, if the upper cover 88 tries to shift horizontally, the outer periphery 88b comes into contact with the upper end of the surrounding cover 89 horizontally, thereby preventing the upper cover 88 from shifting.

[0141] The waterproof cover 87 (each plate-shaped member 89a of the upper cover 88 and the surrounding cover 89) may be made of a metal that can transmit neutrons and gamma rays. This also provides the effect of protecting the measurement system inside the waterproof cover 87 from external electromagnetic noise.

[0142] The present invention is not limited to the embodiments described above, and various modifications can be made within the scope of the technical idea of ​​the present invention. For example, one or more components described in the claims and this specification can be omitted, or any combination of the components described in the claims and this specification can be used, to the extent that at least some of the above-described problems can be solved, or at least some of the above-described effects can be obtained.

[0143] Furthermore, you may adopt any one of the following modification examples 1 to 3 individually, or you may adopt two or more of modification examples 1 to 3 in appropriate combination. In this case, the points not mentioned below are the same as above. Note that all of the following modification examples 1 to 3 may also be applied when adopting the above configurations A and B.

[0144] (Modification Example 1) In the second embodiment described above, the configuration shown in Figure 3C may be adopted. That is, the reflective portion 13b may also be provided in the predetermined region described above, and may cover the entire area around the deceleration portion 13a.

[0145] (Example of modification 2) The neutron source 11 may be placed inside the deceleration unit 13a so that it is covered by the deceleration unit 13a not only from the sides and rear but also from the front. That is, the neutron source 11 may be located in the middle of the deceleration unit 13a in the forward direction so that it is embedded inside the deceleration unit 13a.

[0146] (Modification Example 3) In the first or second embodiment described above, the deceleration unit 13a, the reflecting unit 13b, etc. may be configured as follows. Figures 14A and 14B show an example of the configuration of Modification Example 3 in the first or second embodiment. Figure 14A is a view of the deceleration unit 13a, the reflecting unit 13b, etc. from the front, and Figure 14B is a view taken along the line 14B-14B in Figure 14A.

[0147] The reflective section 13b has a first block body B1 and a second block body B2. Each of the first block body B1 and the second block body B2 is a block-shaped member formed from the neutron reflecting material (e.g., graphite) described above.

[0148] Figures 15A and 15B show the state in which the closing member 92 (described later) has been removed from Figure 14A and 14B, respectively, and the deceleration unit 13a and the second block body B2 have been removed from the insertion hole H (described later) in the first block body B1. As shown in Figures 15A and 15B, the first block body B1 has an insertion hole H into which the deceleration unit 13a and the second block body B2 can be inserted laterally. In the state shown in Figures 15A and 15B, this insertion hole H is open in the forward direction and also opens laterally, facing away from the gamma-ray shielding unit 14.

[0149] Figure 15C shows the state in Figure 15B where the deceleration unit 13a is inserted laterally into the insertion hole H from the opposite side of the gamma-ray shielding unit 14. Figure 15D shows the state in Figure 15C where the second block body B2 is further inserted laterally into the insertion hole H from the opposite side of the gamma-ray shielding unit 14. The insertion hole H may penetrate the first block body B1 laterally. In this case, the first neutron absorption unit 15 may be positioned at the tip of the insertion hole H on the gamma-ray shielding unit 14 side. The first neutron absorption unit 15 may be attached to the first block body B1 by appropriate means (for example, fitting into the guide unit 91 described later or by adhesive). The gamma-ray shielding unit 14 may also be coupled to the first neutron absorption unit 15 by appropriate means (for example, by adhesive).

[0150] As shown in Figures 15A and 15B, the first block body B1 is provided with a guide portion 91 extending laterally on the inner surface of the insertion hole H, and the deceleration unit 13a is fitted to the guide portion 91 so as to be movable laterally. The guide portion 91 may be provided at two locations that sandwich the deceleration unit 13a and the second block body B2 in the vertical direction.

[0151] In the examples shown in Figures 15A to 15D, the guide section 91 is a rail extending laterally, the deceleration section 13a has a groove 13ag extending laterally to fit into the rail 91, and the second block body B2 similarly has a groove B2g extending laterally to fit into the rail 91. The rail 91 may be joined to the first block body B1 by appropriate means (for example, adhesive). The guide section 91 may also be a guide groove extending laterally formed on the inner surface of the insertion hole H in the first block, in which case the deceleration section 13a and the second block body B2 may be provided with rails that fit into the guide grooves acting as the guide section 91, instead of the grooves 13ag and B2g described above.

[0152] The non-destructive testing device 10 has a closing member 92 that closes the insertion hole H. That is, with the deceleration unit 13a and the second block body B2 inserted laterally into the insertion hole H along the guide unit 91, the closing member 92 laterally closes the insertion hole H from the opposite side of the gamma-ray shielding unit 14, preventing the second block B2 from coming out of the insertion hole H. With the insertion hole H closed in this manner, the closing member 92 is attached to the first block body B1 (via the outer plate 93 described later). The closing member 92 may be a plate-shaped member.

[0153] The method of attaching the closing member 92 to the first block body B1 is not particularly limited, but for example, as shown in Figures 14A and 14B, the closing member 92 may be attached to the first block body B1 together with other members so as to surround the reflective portion 13b (first block body B1 and second block body B2) when viewed from the front. In the example of Figures 14A and 14B, the other members are the outer plate 93, the rod-shaped member 94, and the tip plate 95.

[0154] The outer plate 93 is located on both outer surfaces of the first block body B1 in the longitudinal direction, which is perpendicular to both the lateral and forward directions.

[0155] Two pairs of rod-shaped members 94 are provided. One pair of these two pairs sandwiches the first block body B1. Each pair of rod-shaped members 94 is positioned to sandwich a part of the first block body B1 in the forward direction and extends in the lateral direction. For each rod-shaped member 94, a screw hole 94h is formed on the lateral end face opposite to the gamma-ray shielding portion 14, and a through hole 92h is formed in the plate-shaped closing member 92 through which a screw penetrates in the thickness direction. The closing member 92 may be attached to the rod-shaped member 94 by screwing the screw through the through hole 92h into the corresponding screw hole 94h.

[0156] Multiple screw holes (not shown) may be formed on the vertical outer surface of each rod-shaped member 94, and multiple through holes (not shown) may be provided in the outer plate 93 through which screws penetrate in the thickness direction. The outer plate 93 may be attached to the rod-shaped member by screwing the screws into the screw holes through each of the through holes.

[0157] The tip plate 95 is attached to the rod-shaped member 94 and sandwiches the first block body B1 between it and the closing member 92. In the example shown in Figure 14A, two tip plates 95 are arranged on both sides of the gamma-ray shielding section 14 in the vertical direction. Screw holes (not shown) are also formed on the lateral end face of each rod-shaped member 94 on the gamma-ray shielding section 14 side, and through holes (not shown) are also formed in the tip plate 95 through which screws penetrate in the thickness direction. The tip plate 95 can be attached to the corresponding rod-shaped member 94 by screwing the screws through the through holes into the corresponding screw holes.

[0158] The guide portion 91 (rail), closing member 92, outer plate 93, rod-shaped member 94, and tip plate 95 described above may be made of, for example, metal (e.g., aluminum).

[0159] In the second embodiment, the deceleration unit 13a, the first block body B1, the second block body B2, the neutron shielding unit 13, the first neutron absorption unit 15, the closing member 92, each outer plate 93, each rod-shaped member 94, and each tip plate 95 may be included in the above-mentioned plurality of components of the radiation source unit U1. In this case, for example, a plurality of screw holes (not shown) may be formed on the rear surface (lower surface in Figure 15B) of the rear rod-shaped member 94 of each pair of rod-shaped members 94, a plurality of through holes may be provided in the first base 81 through which screws penetrate in the thickness direction, and the first base 81 may be attached to the rod-shaped members 94 by screwing the screws into the screw holes through each of the through holes.

[0160] According to the third modification example, the deceleration unit 13a and the reflecting unit 13b can be easily assembled together. Specifically, the deceleration unit 13a and the second block body B2 of the reflecting unit 13b are inserted into the insertion hole H along the guide portion 91 provided on the inner surface of the insertion hole H of the first block body B1 in the reflecting unit 13b, and then the closing member 92 is attached to the first block body B1 so as to close the insertion hole H from the side opposite to the gamma-ray shielding unit 14. In this way, the deceleration unit 13a and the reflecting unit 13b can be easily assembled together so that the deceleration unit 13a and the second block B2 do not come out of the insertion hole.

[0161] Furthermore, since the deceleration unit 13a and the second block body B2 engage with the guide portion 91 in the forward direction (front-back direction), the guide portion 91 prevents the deceleration unit 13a and the second block body B2 from coming out of the insertion hole H in the forward direction.

[0162] 1. Object to be inspected, 1a. Surface, 10. Non-destructive testing equipment, 11. Neutron source, 12. Gamma-ray detector, 12v. Container (vacuum vessel), 13. Neutron shielding section, 13a. Deceleration section, 13a1. Neutron emission surface (front), 13a2. Recess, 13b. Reflection section, 13b1. Front, 14. Gamma-ray shielding section, 14a. Front end surface (slope), 14b. Rear end surface, 15. First neutron absorption section, 15a. Front, 16. Second neutron absorption section, 16a. Front absorption section, 16a1. Front, 16b. Side absorption section, 17. Dewar, 18. Cold finger, 21. Detection amount measuring device, 21a. Amplifier, 21b. Data generation section, 22. Preamplifier, 23. Data processing device, 24. Sub-detector, 24a. Signal output section, 24a1. MPPC, 24a2 Readout board, 31 Support, 31a First support, 31b Second support, 31c Third support, 31p Through hole, 32 Base, 32a First base, 32b Second base, 32b1 Screw hole, 32c Third base, 33 Position adjustment mechanism, 34 Unit, 71 Neutron generation tube, 71a Ion source, 71b Accelerator, 81 First base, 82 Second base, 82s Support leg, 83 Third base, 83h Through hole, 84 Support structure, 84a First mounting part, 84b Second mounting part, 84bs Slider, 84c Third mounting part, 84d Column member, 84e Installation part, 84f Guide mechanism (rail), 84g Stopper, 84h Through hole, 85 Detachable device, 85a First member, 85a1 Slotted hole, 85b Second member, 85c Movable part, 85c1 Engaging part, 85c2 Operating part, 85c3 Diameter enlarged part, 85d Spring, 85h1 Through hole, 85h2 Through hole, 86 Rejection signal generation part, 86a Amplifier, 86b Signal output part, 87 Waterproof cover, 88 Upper cover, 88a Upper part, 88b Outer periphery, 89 Surrounding cover, 89a Plate-shaped member, 89b Upper opening, 91 Guide part, 92 Closing member, 93 Outer plate, 94 Rod-shaped member, 95 Tip member, Ax Central axis, B1 First block body, B2 Second block body, H Insertion hole, R Gamma ray entry area, U1 Radiation source unit, U2 Main detector unit, U3 Sub-detector unit

Claims

1. A non-destructive testing apparatus comprising: a neutron source that spontaneously generates and emits neutrons; a gamma-ray detector that detects gamma rays generated within an object to be inspected by neutrons incident on the object to be inspected in front of the neutron source; a deceleration unit arranged side-by-side with the gamma-ray detector in a direction laterally to the forward direction from the rear of the neutron source, formed of a neutron-decelerating material, and covering the periphery of the neutron source when viewed from the front; and a reflective unit formed of a neutron-reflecting material, covering the periphery of the deceleration unit except for a predetermined area on the gamma-ray detector side when viewed from the deceleration unit.

2. The non-destructive testing apparatus according to claim 1, comprising a neutron absorbing section formed of a neutron-absorbing material, which is disposed between the deceleration section and the gamma-ray detector in the lateral direction, and the neutron absorbing section is located in the predetermined region.

3. The non-destructive testing apparatus according to claim 2, wherein the neutron absorbing portion is sandwiched between the reflecting portions in a vertical direction perpendicular to the forward direction and the lateral direction, respectively.

4. The non-destructive testing apparatus according to claim 2, wherein the neutron absorption section directly covers the deceleration section from the side of the gamma-ray detector.

5. The non-destructive testing apparatus according to claim 1, wherein the reflective portion does not have a portion that overlaps with the deceleration portion in the lateral direction on the gamma-ray detector side of the deceleration portion.

6. The non-destructive testing apparatus according to claim 2, further comprising a gamma-ray shielding unit disposed between the neutron absorption unit and the gamma-ray detector in the lateral direction for shielding gamma rays.

7. The non-destructive testing apparatus according to claim 6, wherein the reflecting portion comprises a first block body and a second block body, the first block body has an insertion hole formed therein into which the deceleration portion and the second block body can be inserted laterally, the deceleration portion is provided with a guide portion on the inner surface of the insertion hole, the deceleration portion and the second block body are fitted laterally movably into the guide portion, and the apparatus includes a closing member that closes the insertion hole from the opposite side of the gamma-ray shielding portion to prevent the deceleration portion and the second block body from coming out of the insertion hole when the deceleration portion and the second block body are inserted into the insertion hole along the guide portion.

8. A non-destructive testing apparatus comprising: a source unit including a neutron source that spontaneously generates and emits neutrons; a neutron shielding unit that shields the neutrons around the neutron source by covering it from the periphery, thereby enabling the emission of neutrons toward the front of the neutron source; a main detector unit including a gamma-ray detector that detects gamma rays generated within an object to be inspected by neutrons incident on the object to be inspected toward the front of the neutron source; and a sub-detector unit including a sub-detector that outputs an incident signal when gamma rays are incident on it, wherein the source unit, the main detector unit, and the sub-detector unit are detachable from each other, and when attached to each other, the neutron shielding unit and the gamma-ray detector are positioned side by side, and the sub-detector is positioned around the gamma-ray detector.

9. The non-destructive testing apparatus according to claim 8, comprising a support structure having a first mounting portion from which the radiation source unit can be attached and detached, a second mounting portion from which the main detector unit can be attached and detached, and a third mounting portion from which the sub-detector unit can be attached and detached, wherein the radiation source unit, the main detector unit, and the sub-detector unit are detachable from each other via the support structure.

10. The non-destructive testing apparatus according to claim 9, wherein the support structure includes a guide mechanism that makes the second mounting portion slidable relative to the third mounting portion, and the gamma-ray detector can be positioned in the region surrounded by the sub-detectors by sliding the second mounting portion while the main detector unit is attached to the second mounting portion.

11. The non-destructive testing apparatus according to claim 10, wherein a through hole is formed in the third mounting portion, and the gamma-ray detector of the main detector unit can be positioned in the region surrounded by the sub-detector by sliding the second mounting portion so that the gamma-ray detector of the main detector unit passes through the through hole while the main detector unit is mounted on the second mounting portion.

12. A neutron source that spontaneously generates and emits neutrons; a neutron shielding unit that shields the neutrons around the neutron source by covering it from the surroundings, thereby enabling the emission of neutrons toward the front of the neutron source; and a gamma-ray detector that detects gamma rays generated within an object under inspection by neutrons incident on the object under inspection toward the front of the neutron source, and outputs a detection signal related to said detection, wherein the direction from the rear to the front of the neutron source is defined as the forward direction, and the neutron shielding unit and the gamma-ray detector are arranged side by side in the lateral direction relative to the forward direction, and a sub-detector is provided located around the gamma-ray detector, wherein when gamma rays are incident on the gamma-ray detector, the gamma-ray detector outputs an analog detection signal, and when gamma rays are incident on the sub-detector, the sub-detector outputs an analog incident signal. A non-destructive testing apparatus comprising: a detection amount measuring device that generates and outputs detection data of digital data indicating the amount of gamma rays detected at each energy of gamma rays based on each of the detection signals from the gamma-ray detector; and a rejection signal generating unit that outputs a rejection signal to the detection amount measuring device indicating that the use of the detection signal is to be refused when an incident signal is output from the sub-detector.

13. A non-destructive testing apparatus according to claim 12, comprising a data processing device that performs processing for inspecting the object to be inspected on the detection data from the detection amount measuring device, wherein the detection amount measuring device and the rejection signal generation unit are made of hardware, and the data processing device is a computer that operates by software.

14. The non-destructive testing apparatus according to claim 12 or 13, wherein the sub-detector is integrated with the gamma-ray detector so as to cover it from the surroundings.

15. A non-destructive testing apparatus comprising: a neutron source that spontaneously generates and emits neutrons; a neutron shielding unit that shields the neutrons around the neutron source by covering it from the surroundings, thereby enabling the emission of neutrons toward the front of the neutron source; and a gamma-ray detector that detects gamma rays generated within an object to be inspected by neutrons incident on the object to be inspected toward the front of the neutron source, and outputs a detection signal related to said detection, wherein the direction from the rear to the front of the neutron source is defined as the forward direction, the neutron shielding unit and the gamma-ray detector are arranged side by side in the lateral direction relative to the forward direction, the front side is upward, and the apparatus is equipped with a waterproof cover that covers the main body, including the neutron source, the neutron shielding unit and the gamma-ray detector, from above and from the sides, thereby preventing rainwater from entering the main body.

16. The non-destructive testing apparatus according to claim 15, wherein the waterproof cover comprises an upper cover that covers the main body from above and a peripheral cover that covers the main body from all sides, the peripheral cover has an internal space in which the main body is located, and the upper cover has an upper part that covers the upper opening of the internal space and an outer peripheral part that extends downward from the outer peripheral edge of the upper part and covers the upper end of the peripheral cover from all sides.

Images