Inspection device, inspection system, and inspection method

Abstract

[Problem] To appropriately inspect an object to be inspected. [Solution] An inspection device 110 is disposed between an inner container 210 and an outer container 220 of a double container in which parts of the inner container 210 and the outer container 220 are cylindrical, and comprises an inspecting unit 114 that inspects the inner container 210, a main body 111 that is provided with wheels 1110a so as to be capable of traveling, and arms 112, 113 that include a radial restriction mechanism 1121 for restricting movement of the main body 111 in the radial direction of the double container, wherein the inspection device 110 travels in the circumferential direction along an inner surface of the outer container 220 in a state in which any surface of the main body 111 is in contact with a vertically upper surface of a guide 120 that extends in the circumferential direction of the outer container 220.

Description

Inspection device, inspection system, and inspection method

[0001] This application claims the benefit of priority to Japanese Patent Application No. 2024-12762, filed on January 31, 2024, the contents of which are incorporated herein by reference.

[0002] Pressure vessels used in nuclear power plants, chemical plants, and other plants are made of annular metal plates. For example, some pressure vessels have a double structure consisting of an inner vessel with a body made of vertically stacked steel plates welded together at the boundary, and an outer vessel surrounding the inner vessel. Because welded joints, which are the boundaries between welded metal plates, are more susceptible to fracture due to stress concentration than non-welded parts, inspections of the welded joints of the inner vessel are regularly conducted.

[0003] Inspection of the welded joint of the inner vessel is performed by remotely operating an inspection device equipped with a sensor and placing it at an inspection location. For example, in the technology described in Patent Document 1, a marker is permanently installed at the welded joint of the inner vessel, and the inspection device travels along the surface of the inner vessel using the marker as a guide. The inspection device performs ultrasonic flaw detection on the welded joint of the inner vessel while traveling along the surface of the inner vessel.

[0004] In the technology described in Patent Document 2, a track formed by a rack gear is arranged along the welded joint of the inner vessel. The rack gear is engaged with a pinion gear of an inspection device, and the inspection device performs ultrasonic flaw detection on the welded joint of the inner vessel while traveling on the surface of the inner vessel.

[0005] JP-A-4-290996 Patent No. 1614782

[0006] However, the technology of Patent Document 1 has a problem in that when the inspection device travels horizontally along the welded joint, it is affected by gravity and deviates from the horizontal traveling line along the welded joint. Therefore, it is necessary to control the traveling line of the inspection device to correct it, or to carry out an inspection that takes into consideration in advance the deviation of the inspection device from the traveling line.

[0007] Furthermore, in the technology described in Patent Document 2, it is necessary to mate the rack gear with the pinion gear of the inspection device, making it difficult to install and remove the inspection device by remote control. Therefore, workers must install and remove the inspection device, and the inspection device is not suitable for inspecting pressure vessels, which can be subject to high temperatures, high radiation, and confined environments.

[0008] Therefore, an object of the present disclosure is to provide an inspection device, an inspection system, and an inspection method that are capable of properly inspecting an object to be inspected.

[0009] An inspection device according to one aspect of the present disclosure is an inspection device that is placed between an inner container and an outer container in a double container in which portions of the inner container and outer container are cylindrical in shape, and is equipped with an inspection unit that inspects the inner container, a main body that is provided with wheels for movement, and an arm that has a radial restriction mechanism that restricts the radial movement of the double container in the main body, and runs circumferentially around the inner surface of the outer container with one surface of the main body in contact with the vertical upper surface of a guide that extends circumferentially around the outer container.

[0010] The arm may include a first arm extending from the main body toward the inner container, and a second arm connected to the first arm and having the inspection unit movably mounted in the vertical direction.

[0011] The first arm may restrict radial movement of the double container in the main body by pressing the second arm against an outer surface of the inner container.

[0012] The first arm may include an elastic body, and the elastic force of the elastic body may be used to release the restriction on radial movement of the double container in the main body.

[0013] The inspection device may further include a position control mechanism that controls the inspection device to a start position for inspection, and the position control mechanism may detect an indicator representing a reference position provided on the guide and identify the reference position as the position of the inspection device in the double container.

[0014] The guide extending in the circumferential direction of the outer container may be provided with at least one gap, and the gap may be of a length that does not interfere with the circumferential movement of the inspection device.

[0015] An inspection system according to one aspect of the present disclosure may include the inspection device, a guide extending circumferentially in the outer container of the double container, and a control device that controls the inspection device.

[0016] An inspection method according to one aspect of the present disclosure uses an inspection device that includes an inspection unit that is positioned between the inner container and the outer container and inspects the inner container, a main body that is provided with wheels for movement, and an arm that has a radial limiting mechanism that limits radial movement of the double container on the main body, in a double container in which portions of the inner container and outer container are cylindrical, and includes the steps of suspending the inspection device and positioning it so that one surface of the main body is in contact with the vertical upper surface of a guide that extends circumferentially of the outer container, activating the radial limiting mechanism to limit radial movement of the double container of the inspection device, driving the wheels to move the inspection device circumferentially of the double container, inspecting the inner container, and stopping the radial limiting mechanism and hoisting the inspection device.

[0017] When the inspection device is in contact with the guide, vertical downward movement may be restricted, but vertical upward movement may not be restricted.

[0018] According to the present disclosure, it is possible to properly inspect an inspection target.

[0019] FIG. 1 is a perspective view showing a pressure vessel to be inspected. FIG. 2 is a diagram showing the general relationship between the devices that make up the inspection system. FIG. 3 is a perspective view showing the inspection device. FIG. 4A is a schematic view showing an arm in the inspection device when the radial direction limiting mechanism is not activated. FIG. 4B is a schematic view showing an arm in the inspection device when the radial direction limiting mechanism is activated. FIG. 5A is a perspective view showing a pressure vessel provided with a guide. FIG. 5B is a horizontal cross-sectional view of a pressure vessel provided with a guide. FIG. 5C is a vertical cross-sectional view of a pressure vessel provided with a guide. FIG. 6 is a functional block diagram of a control device included in the inspection system. FIG. 7 is a flowchart showing the processing flow of an inspection method implemented by the inspection system. FIG. 8 is a perspective view explaining the configuration of an inspection device according to a modified example.

[0020] Embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings. The dimensions, materials, and other specific values ​​shown in the embodiments are merely examples for ease of understanding and, unless otherwise specified, do not limit the present disclosure. Furthermore, the relative sizes of components shown in each drawing do not necessarily accurately represent the actual size relationships between the components. In this specification and drawings, elements having substantially the same function and configuration are designated by the same reference numerals to avoid redundant description, and elements not directly related to the present disclosure are not shown.

[0021] An overview of an inspection system 100 according to one embodiment of the present invention will be described. The inspection system 100 is a system including an inspection device 110 that performs various inspections on a pressure vessel 200 used in a plant such as a nuclear plant or a chemical plant.

[0022] 1 is a perspective view of a pressure vessel 200 to be inspected in accordance with the present disclosure. For example, the pressure vessel 200 is a double vessel including an inner vessel 210 and an outer vessel 220, as shown in FIG.

[0023] The inner vessel 210 is a cylindrical vessel having a body portion formed by stacking annular metal plates 211 in the vertical direction and welding their boundaries 212 in the circumferential direction. Hereinafter, the welded boundaries 212 will be referred to as weld joints 212.

[0024] The inner container 210 is provided inside the outer container 220. Both the outer container 220 and the inner container 210 are containers having a partially cylindrical shape. A space V is generated between the inner container 210 and the outer container 220, which are contained within the outer container 220. The outer container 220 is also provided with at least one opening 221 that connects the space V with the outside of the pressure vessel 200. In the present disclosure, four openings 221 are provided at 90-degree intervals around the central axis of the outer container 220.

[0025] For example, in the inspection system 100, the inspection device 110 is placed in the space V from the outside of the pressure vessel 200 via the opening 221. The inspection device 110 performs an inspection of the pressure vessel 200 while moving through the space V. Specific examples of the inspections performed by the inspection device 110 include ultrasonic flaw detection, X-ray transmission inspection, eddy current inspection, penetrant inspection, magnetic particle inspection, and non-destructive inspection such as visual inspection. In the present disclosure, the inspection system 100 will be described for performing an ultrasonic flaw detection inspection on a weld joint 212 of an inner vessel 210, taking as an example a case where the pressure vessel 200 described above is a double-walled pressure vessel used in a nuclear power plant.

[0026] 2 is a diagram illustrating the schematic relationship between the devices that make up the inspection system 100. In FIG. 2 and the following figures of this disclosure, the inspection device 110 is used as the reference, and the perpendicularly intersecting X-axis (radial direction), Y-axis (circumferential direction, circumferential tangential direction), and Z-axis (vertical direction) are defined as shown.

[0027] As shown in FIG. 2, the inspection system 100 includes the above-described inspection device 110, a guide 120 provided in the pressure vessel 200, a control device 130, and a transport device 140.

[0028] The guide 120 is a protruding member that protrudes radially inward from the inner surface of the outer container 220. The guide 120 extends in the circumferential direction of the outer container 220. For example, the guide 120 is provided on the inner surface of the outer container 220 at a position corresponding to the weld joint 212 of the inner container 210.

[0029] The inspection device 110 inspects the inner vessel 210 using, for example, ultrasonic waves. In the present disclosure, the inspection device 110 performs ultrasonic flaw detection on the weld joint 212 of the inner vessel 210. The inspection device 110 is provided with at least one wheel on each of the vertical upper surface and the vertical lower surface. The inspection device 110 is placed in the space V of the pressure vessel 200 with the wheel on the vertical lower surface in contact with the vertical upper surface of the guide 120 and the wheels on both sides parallel to the vertical direction in contact with the inner surface of the outer vessel 220. In this state, the inspection device 110 performs ultrasonic flaw detection on the weld joint 212 of the inner vessel 210 while moving circumferentially around the inner surface of the outer vessel 220. The inspection device 110 is also communicatively connected to a control device 130 (described later) via a cable.

[0030] The transport device 140 places the inspection device 110 in the space V of the pressure vessel 200. Each component of the inspection system 100 will be described in detail below.

[0031] FIG. 3 is a perspective view illustrating the configuration of the inspection device 110 included in the inspection system 100. As shown in FIG.

[0032] As shown in FIG. 3, the inspection device 110 includes a main body 111, a first arm 112, a second arm 113, and an inspection unit 114.

[0033] The main body 111 has a rectangular parallelepiped shape and is provided with a traveling mechanism 1110 and a position control mechanism 1111.

[0034] The traveling mechanism 1110 is a mechanism for causing the inspection device 110 to travel on the inner surface of the outer container 220. The traveling mechanism 1110 includes wheels 1110a.

[0035] The wheels 1110a have a cylindrical shape. The wheels 1110a are provided on the main body 111 so that the circular surfaces of the wheels 1110a are parallel to each of the planes (XY planes) parallel to the vertical direction of the main body 111. In the present disclosure, two wheels 1110a are provided on each of the planes parallel to the vertical direction of the main body 111. For example, the vertical upper surface of the main body 111 faces the vertical lower surface of each wheel 1110a. Furthermore, the vertical lower surface of the main body 111 faces the vertical upper surface of each wheel 1110a. Each of the wheels 1110a provided on the vertical upper and lower surfaces of the main body 111 may be provided so that at least a portion thereof protrudes radially or circumferentially from the vertical upper and lower surfaces of the main body 111.

[0036] When the inspection device 110 is placed in the space V of the pressure vessel 200, the outer circumferential surfaces of the wheels 1110a provided on the vertical upper and lower surfaces of the main body 111 contact the inner surface of the outer vessel 220 (see FIG. 2). Also, the lower vertical surface of the wheel 1110a provided on the vertical lower surface of the main body 111 contacts the vertical upper surface of the guide 120 (see FIG. 2).

[0037] The wheels 1110a are driven by a drive device (not shown in Fig. 3) The drive device that drives the wheels 1110a is, for example, a motor.

[0038] In the present disclosure, two wheels 1110a are provided on each of the upper and lower vertical surfaces of the main body 111. However, the number of wheels 1110a provided is not particularly limited. In the present disclosure, the traveling mechanism 1110 may be composed of only the wheels 1110a, or may further include other components. Examples of other components include a damper or a brake device. For example, the damper absorbs vibrations that occur in the wheels 1110a due to the undulations of the inner surface of the outer container 220. In addition, the brake device applies a braking force to the wheels 1110a to stop the traveling of the inspection device 110.

[0039] The position control mechanism 1111 is a mechanism for controlling the movement of the inspection device 110 to the inspection start position. The position control mechanism 1111 identifies the position of the inspection device 110 based on a reference position linked to position information in the pressure vessel 200. The position control mechanism 1111 then controls the movement of the inspection device 110 to the inspection start position. For this purpose, the position control mechanism 1111 has a reference position detection sensor.

[0040] The reference position detection sensor is a sensor that detects an index 123 that indicates a reference position and is provided on the guide 120 (described later). The type of reference position detection sensor is determined appropriately depending on the index 123 provided on the guide 120. In the present disclosure, a notch is provided on the vertical upper surface of the guide 120 as the index 123 that indicates the reference position. However, the index 123 is not limited to a notch. Another example of the index 123 is a protrusion that protrudes vertically upward from the vertical upper surface of the guide 120. When a notch or a protrusion is provided as the index 123, the distance between the main body 111 and the position on the vertical upper surface of the guide 120 where the index 123 is provided differs from the distance between the main body 111 and the position on the vertical upper surface of the guide 120 where the index 123 is not provided. Therefore, in the present disclosure, a distance detection sensor that detects the distance between the main body and the vertical upper surface of the guide 120 is used as the reference position detection sensor. Here, the distance detection sensor may be an eddy current distance detection sensor or an optical distance detection sensor. The reference position detection sensor may also be one that detects the reference position using a mechanical switch.

[0041] The position control mechanism 1111 determines the presence or absence of the index 123 based on the distance between the main body 111 and the vertical upper surface of the guide 120 detected by the reference position detection sensor. For example, if the distance between the main body 111 and the vertical upper surface of the guide 120 has changed by a predetermined value or more compared to the previously detected distance, the position control mechanism 1111 determines that the index 123 is provided at the position where the distance has changed by more than the predetermined value. The position control mechanism 1111 sets the position determined to be where the index 123 is provided as a reference position, and controls the movement of the inspection device 110 to an inspection start position using the reference position as a starting point.

[0042] One end of the first arm 112 is connected to a surface on the inner container 210 side of a plane (XZ plane) parallel to the circumferential tangent direction of the main body 111. The other end of the first arm 112 is connected to a second arm 113, which will be described later. The first arm 112 has a first support column 1120, a radial limiting mechanism 1121, and an actuator 1122. The first support column 1120 is provided on one end side. The radial limiting mechanism 1121 is provided on the other end side. The actuator 1122 activates the radial limiting mechanism 1121. The radial limiting mechanism 1121 is connected to the second arm 113, which will be described later. In the present disclosure, the radial limiting mechanism 1121 has a pantograph-type configuration. The radial limiting mechanism 1121 having a pantograph-type configuration will be described below.

[0043] The radial direction limiting mechanism 1121 has a pantograph 1121a consisting of pantograph arms that intersect in the XY plane or the XZ plane. In the present disclosure, the radial direction limiting mechanism 1121 is composed of two pantographs 1121a having pantograph arms that intersect in the XY plane. The end of each pantograph 1121a on the outer container 220 side is connected to the first support column 1120 via a base 1121b. The end of each pantograph 1121a on the inner container 210 side is connected to the second arm 113 via a support base 1121c.

[0044] The actuator 1122 activates the radial direction limiting mechanism 1121. For example, the actuator 1122 is provided inside the first support 1120 of the first arm 112. The actuator 1122 reduces the distance between one ends of the pantograph arms at the ends of the pantographs 1121a on the outer surface side of the outer container 220. This causes the pantographs 1121a to expand in the radial direction, and the first arms 112 to expand in the radial direction. The expansion of the first arms 112 will be described in detail later with reference to other drawings.

[0045] The second arm 113 has a second support 1130 and a ball plunger 1131. For example, the second arm 113 has the ball plungers 1131 provided on both ends of the second support 1130. In the space V of the pressure vessel 200, the second arm 113 is arranged so that the longitudinal direction of the second support 1130 is vertical. That is, the second support 1130 is arranged so that the longitudinal direction is positioned perpendicular to the weld joint 212 of the inner vessel 210 in the space V of the pressure vessel 200 (see FIG. 2). The second support 1130 is connected near its middle portion to the other end of the first arm 112. In addition, the second support 1130 is provided with an inspection unit 114 (described later) that is movable along the second support 1130. For example, the second support 1130 is provided with a slide mechanism. By operating the slide mechanism, the inspection unit 114 is moved (scanned) in the vertical direction along the length of the second support column 1130 in a range from one end to the other end.

[0046] The ball plunger 1131 has a spring (not shown) and a ball 1131a inside the main body. In the main body of the ball plunger 1131, the spring and ball 1131a are arranged in this order from the end of the ball plunger 1131 on the second support post 1130 side. The ball 1131a is provided rotatably. Furthermore, the ball 1131a may be provided so that a portion thereof protrudes radially inward.

[0047] Hereinafter, the first arm 112 and the second arm 113 described above may be collectively referred to as "arms." An example of the operation of the arms in the inspection device 110 will be described below. FIGS. 4A and 4B are diagrams showing the operation of an arm including a radial limiting mechanism 1121 having a pantograph-type configuration. Also, FIGS. 4A and 4B are simplified diagrams of the inspection device 110 in FIG. 2 as seen from vertically above. FIG. 4A is a schematic diagram showing the arm in a state in which the radial limiting mechanism 1121 is not activated. FIG. 4B is a schematic diagram showing the arm in a state in which the radial limiting mechanism 1121 is activated.

[0048] When the radial limiting mechanism 1121 is not activated, the first arm 112 is in a state in which the pantograph 1121a is not extended, as shown in FIG. 4A . Here, the elastic body 1121d provided between the base 1121b and the support base 1121c prevents the pantograph 1121a from contracting more than necessary when the radial limiting mechanism 1121 is not activated. When the radial limiting mechanism 1121 is not activated, the device length ML, which is the length from the inner surface of the outer container 220 to the end of the ball plunger 1131 on the inner container 210 side, is shorter than the distance D from the inner surface of the outer container 220 to the outer surface of the inner container 210. Therefore, the inspection device 110 can move radially within the space V of the pressure vessel 200.

[0049] It is preferable that the device length ML when the pantograph 1121a is not extended is shorter than the distance from the radial inner surface of the guide 120 to the outer surface of the inner container 210. This allows the inspection device 110 to pass between the guide 120 and the outer surface of the inner container 210. As a result, the inspection device 110 can freely move vertically in the space V of the pressure vessel 200 from the vertical lower surface to the upper surface of the outer container 220.

[0050] Therefore, when the radial limiting mechanism 1121 is not activated, the inspection device 110 can move vertically and radially within the space V of the pressure vessel 200. When the inspection device 110 is disposed so as to contact the vertical upper surface of the guide 120 and the radial limiting mechanism 1121 is activated from a state in which the inspection device 110 has been vertically positioned, the actuator 1122 extends the pantograph 1121a radially inward. As a result, as shown in FIG. 4B , the ball 1131a of the ball plunger 1131 of the second arm 113 is pressed against the outer surface of the inner container 210. At this time, the device length ML coincides with the distance D from the inner surface of the outer container 220 to the outer surface of the inner container 210.

[0051] When the radial direction limiting mechanism 1121 is activated and the device length ML is equal to the distance D, the inspection device 110 is in a tensioned state between the outer surface of the inner container 210 and the inner surface of the outer container 220. This positional relationship makes it possible to limit the radial movement of the pressure vessel 200 in the inspection device 110, particularly the radially inward movement of the inspection device 110. On the other hand, the inspection device 110 can move in the circumferential direction by rolling the wheel 1110a and the ball 1131a of the ball plunger 1131.

[0052] When the operation of the radial limiting mechanism 1121 is released from a state in which the inspection device 110 is stretched between the outer surface of the inner container 210 and the inner surface of the outer container 220, an elastic force acts in the direction in which the elastic body 1121d contracts, i.e., in the direction in which the pantograph 1121a contracts. This elastic force causes the pantograph 1121a to contract, and the device length ML becomes shorter than the distance D. Therefore, by releasing the operation of the radial limiting mechanism 1121, the restriction on the radially inward movement of the inspection device 110 is released. This allows the inspection device 110 to be retrieved from the space V of the pressure vessel 200.

[0053] Furthermore, even if the inspection device 110 is cut off due to a malfunction or the like, the actuator 1122 stops operating and an elastic force acts in the direction of contraction of the elastic body 1121d, thereby releasing the restriction on the radially inward movement of the inspection device 110. Therefore, even if the inspection device 110 is cut off due to a malfunction or the like, the restriction on the radial movement of the inspection device 110 is released, and the inspection device 110 can be recovered from the space V of the pressure vessel 200.

[0054] When the pantograph 1121a is retracted and the device length ML becomes smaller than the distance from the radial inner surface of the guide 120 to the outer surface of the inner container 210, the inspection device 110 can freely move vertically from the vertical lower surface to the upper surface of the outer container 220 in the space V of the pressure vessel 200. This allows the inspection device 110 to move freely in the pressure vessel 200 from the guide 120 in which it is currently located to another guide 120 located vertically above or below it by releasing the radial direction limiting mechanism 1121.

[0055] The inspection unit 114 inspects the inner container 210 as the inspection target. For example, the inspection unit 114 is an ultrasonic sensor for performing ultrasonic flaw detection inspection on the weld joint 212 of the inner container 210. In this case, the inspection unit 114 transmits ultrasonic waves to the weld joint 212 and receives the ultrasonic waves reflected by the weld joint 212. The inspection system 100 analyzes the ultrasonic waves received by the inspection unit 114 to inspect whether or not defects such as scratches have occurred in the weld joint 212. Therefore, the inspection unit 114 includes a transmitting unit and a receiving unit. The transmitting unit has a vibrator that transmits ultrasonic waves. The receiving unit has a vibrator that receives ultrasonic waves. The inspection unit 114 scans the second arm 113 in the vertical direction within a range from one end to the other end of the second support column 1130 in the longitudinal direction. This allows the inspection unit 114 to inspect a wide area near the weld joint 212, which is the inspection target.

[0056] Although the present disclosure provides an example in which the inspection unit 114 is provided with an ultrasonic wave transmitting unit and an ultrasonic wave receiving unit separately, the present invention is not limited to this. The inspection unit 114 may also be provided with an ultrasonic wave transmitting / receiving unit in which the ultrasonic wave transmitting unit and the ultrasonic wave receiving unit are integrated.

[0057] Furthermore, although an ultrasonic sensor having a vibrator and provided with a transmitter and a receiver is exemplified as the inspection unit 114 in this disclosure, the inspection unit 114 is not limited to this. The inspection unit 114 may also be an ultrasonic sensor that combines a magnet and a coil that can electromagnetically transmit and receive ultrasonic waves.

[0058] The guide 120 assists the travel of the inspection device 110 in the space V of the pressure vessel 200. Fig. 5A is a perspective view showing the pressure vessel 200 provided with the guide 120. Fig. 5B is a horizontal cross-sectional view of Fig. 5A. Fig. 5C is a portion of the vertical cross-sectional view of Fig. 5A.

[0059] As shown in FIG. 5A , the guide 120 extends circumferentially on the inner surface of the outer container 220. For example, the guide 120 extends along the weld joint 212 of the inner container 210. When the inspection device 110 is placed in the space V of the pressure vessel 200, the upper surface of the guide 120 contacts the vertical lower surface of the wheel 1110 a located on the vertical lower surface of the inspection device 110 shown in FIG. 3 . The inspection device 110 is pressed against the upper surface of the guide 120 by gravity. This restricts the vertically downward movement of the inspection device 110. As a result, when the inspection device 110 travels on the inner surface of the outer container 220, it is not affected by gravity and can travel horizontally along the weld joint 212. On the other hand, the vertically upward movement of the inspection device 110 shown in FIG. 3 is not restricted. This allows the inspection device 110 to be easily recovered by moving it to the opening 221 upon completion of the inspection or when a malfunction occurs in the inspection device 110.

[0060] As shown in FIG. 2 , the inspection device 110 is disposed in the space V of the pressure vessel 200 so that the weld joint 212 is located near the middle of the second support column 1130 of the second arm 113. Therefore, the guide 120, which contacts the vertical lower surface of the wheel 1110a located on the vertical lower surface of the inspection device 110, is disposed below the weld joint 212 that the inspection device 110 inspects while traveling. The guide 120 is disposed, for example, vertically below the weld joint 212 by about half the vertical width of the main body 111. As a result, the weld joint 212 is located within the scanning range of the inspection unit 114 of the inspection device 110 while traveling. Furthermore, the inspection device 110 can inspect the weld joint 212 over a wide vertical width. Furthermore, problems such as the ball plunger 1131 coming into contact with the weld joint 212 do not occur.

[0061] The material constituting the guide 120 is appropriately determined depending on the environment of the space V. In the present disclosure, the pressure vessel 200 is a double-vessel vessel used in a nuclear power plant, and therefore the environment of the space V is a high-temperature and high-radiation environment. Therefore, the guide 120 is preferably made of a metal such as iron, lead, or stainless steel. The metal guide 120 thermally expands when exposed to the high-temperature environment of the space V. Therefore, in the inspection system 100 according to the present disclosure, the guide 120 is provided with at least one gap 121 as shown in FIGS. 5A and 5B . The gap 121 absorbs the thermal expansion of the guide 120. Therefore, deformation of the guide 120 due to thermal expansion is suppressed. Furthermore, the gap 121 has a length L that does not interfere with the circumferential movement of the outer vessel 220 of the inspection device 110 shown in FIG. 3 . For example, the length L of the gap 121 is shorter than the diameter of the wheels 1110a of the inspection device 110. As a result, even when the guide 120 is not thermally expanded, the inspection device 110 does not become stuck in the gap 121 due to the wheels 1110a.

[0062] Furthermore, as shown in FIG. 5C , the guide 120 is not completely fixed to the inner surface of the outer container 220. For example, the surface of the guide 120 that contacts the inner surface of the outer container 220 has a recessed portion 122 that corresponds to a pin 222 protruding from the inner surface of the outer container 220. The guide 120 is provided on the inner surface of the outer container 220 by hooking the recessed portion 122 onto the pin 222. Because the guide 120 is not completely fixed to the inner surface of the outer container 220, it allows for slight deformation due to thermal expansion. This makes it possible to suppress deformation of the guide 120 due to thermal expansion compared to when the guide 120 is completely fixed to the inner surface of the outer container 220. Furthermore, even if the guide 120 is deformed or damaged due to thermal expansion, it can be easily replaced.

[0063] The guide 120 is also provided with an index 123 that indicates a reference position (a reference position for identifying the position of the inspection device 110). For example, the index 123 is a notch. The notch as the index 123 is different from the gap 121 described above.

[0064] The control device 130 controls the inspection device 110. For example, the control device 130 controls at least the travel of the inspection device 110. The control device 130 is arranged outside the pressure vessel 200. For example, the control device 130 is wired to the inspection device 110 via a cable and is therefore arranged in a shielded room provided near the opening 221 of the pressure vessel 200. Figure 6 is a functional block diagram of the control device 130 included in the inspection system 100. In Figure 6, dashed arrows indicate the flow of signals. As shown in Figure 6, the control device 130 includes a control unit 131, a communication unit 132, a display unit 133, and a memory unit 134.

[0065] The control unit 131 is composed of a semiconductor integrated circuit including a CPU (Central Processing Unit). The control unit 131 reads programs and parameters for operating the CPU from a ROM (Read-Only Memory). The control unit 131 also works as a work area with a RAM (Random Access Memory) and other electronic circuits to manage and control the entire inspection device 110. The control unit 131 includes a travel control unit 1310, an arm extension / retraction control unit 1311, an origin return control unit 1312, a scanning unit 1313, an abnormality determination unit 1314, and a position information acquisition unit 1315.

[0066] The travel control unit 1310 controls the travel mechanism 1110 to control the travel of the inspection device 110. For example, the travel control unit 1310 can control the rotation and stopping of the wheels 1110a and the rotation direction of the wheels 1110a by controlling the drive device of the wheels 1110a. This allows the inspection device 110 to move forward or stop in any circumferential direction on the inner surface of the outer container 220.

[0067] The arm extension / retraction control unit 1311 controls extension and retraction of the arm of the inspection device 110. For example, the arm extension / retraction control unit 1311 controls the actuator 1122 in the radial direction limiting mechanism 1121 of the first arm 112 to control the extension and retraction of the pantograph 1121a.

[0068] The origin return control unit 1312 controls the movement of the inspection device 110 so that it moves to the inspection start position (origin). For example, the origin return control unit 1312 controls the travel mechanism 1110 to travel the inspection device 110, while detecting an index 123 indicating a reference position provided on the guide 120 using a reference position detection sensor of the position control mechanism 1111. The origin return control unit 1312 identifies the position of the inspection device 110 in the pressure vessel 200 based on position information linked to the position (reference position) where the index 123 is detected, and then controls the movement of the inspection device 110 to the inspection start position.

[0069] The scanning unit 1313 vertically scans the inspection unit 114. For example, the scanning unit 1313 vertically scans the inspection unit 114 by operating a slide mechanism provided on the second support column 1130. More specifically, the scanning unit 1313 vertically scans the inspection unit 114 along the longitudinal direction of the second support column 1130 in a range from one end to the other end.

[0070] The abnormality determination unit 1314 determines whether or not an abnormality exists in the inspection object. Here, an abnormality is a defect such as a scratch or breakage. The abnormality determination unit 1314 receives the inspection result from the inspection unit 114 and determines whether or not an abnormality exists in the inspection object based on the inspection result. For example, the inspection unit 114 performs an ultrasonic flaw detection inspection on the weld joint 212 of the inner container 210. In this case, the abnormality determination unit 1314 acquires information indicating the ultrasonic waves received by the receiving unit of the inspection unit 114 as the inspection result. The abnormality determination unit 1314 determines whether or not an abnormality exists in the weld joint 212, such as a scratch, based on the information indicating the acquired ultrasonic waves.

[0071] The position information acquisition unit 1315 acquires position information of the inspection device 110 in the pressure vessel 200. For example, the inspection device 110 is provided with an encoder for detecting the amount of movement of the inspection device 110. In this case, the position information acquisition unit 1315 acquires information indicating the amount of movement of the inspection device 110 from the inspection start position from the encoder, and acquires position information of the inspection device 110 in the pressure vessel 200.

[0072] Furthermore, the position information acquisition unit 1315 may further acquire position information of the inspection unit 114 on the second support column 1130. For example, an encoder for detecting the amount of movement of the inspection unit 114 is provided on the second arm 113. The position information acquisition unit 1315 acquires the position information of the inspection unit 114 on the second support column 1130 based on information indicating the amount of movement of the inspection unit 114 acquired from the encoder.

[0073] The communication unit 132 communicates with the inspection device 110 via a cable. For example, the communication unit 132 transmits signals for controlling each component of the inspection device 110. The communication unit 132 also receives inspection results from the inspection device 110.

[0074] Various information is displayed on the display unit 133. For example, the display unit 133 displays the location information of the inspection device 110 acquired by the location information acquisition unit 1315, the inspection results received from the inspection unit 114, and the presence or absence of abnormalities in the inspection target.

[0075] The storage unit 134 is composed of a ROM, a RAM, a flash memory, an HDD, etc. The storage unit 134 stores programs and various data used by the control unit 131. For example, the storage unit 134 stores in advance position information of the index 123 indicating the reference position, inspection results when normal, etc. The storage unit 134 also stores inspection results received from the inspection unit 114.

[0076] The carrying device 140 shown in FIG. 2 is a device that carries the inspection device 110. For example, the carrying device 140 carries the inspection device 110 from outside the pressure vessel 200 to the space V through the opening 221 of the outer vessel 220. More specifically, the carrying device 140 carries the inspection device 110 from outside the pressure vessel 200 to the opening 221 of the outer vessel 220. The carrying device 140 suspends the inspection device 110 from the opening 221 using a cable or dedicated wire connecting the inspection device 110 and the control device 130. The carrying device 140 suspends the inspection device 110 vertically downward in the space V and places it on the vertical upper surface of the desired guide 120. Furthermore, the carrying device 140 suspends the inspection device 110 located on the vertical upper surface of the guide 120 to the opening 221 by reeling in the cable connecting the inspection device 110 and the control device 130. The transporting device 140 transports the inspection device 110 from the opening 221 to the outside of the pressure vessel 200. In the present disclosure, a telescopic manipulator is used as the transporting device 140. The telescopic manipulator transports the inspection device 110 between the outside of the pressure vessel 200 and the opening 221 by extending and contracting.

[0077] Next, an inspection method performed by the inspection system 100 will be described. This inspection method uses the inspection device 110. Fig. 7 is a flowchart showing the processing flow of the inspection method performed by the inspection system 100. As shown in Fig. 7, the inspection method includes an installation process S100, a radial direction restriction process S101, a return-to-origin process S102, an inspection process S103, an abnormality determination process S104, a notification process S105, an end determination process S106, a movement process S107, and a collection process S108. Each process will be described below.

[0078] First, the transporting device 140 executes an installation process S100 in which the inspection device 110 is introduced into the space V of the pressure vessel 200 and placed on the desired guide 120. In the installation process S100, the transporting device 140 transports the inspection device 110 to the opening 221. Thereafter, the transporting device 140 suspends the inspection device 110 from the opening 221 using a cable or dedicated wire connecting the inspection device 110 and the control device 130, and places the inspection device 110 in contact with the vertical upper surface of the guide 120.

[0079] Next, the arm extension / retraction control unit 1311 executes a radial direction restriction process S101 that restricts radial movement of the inspection device 110 placed on the guide 120. In the radial direction restriction process S101, the arm extension / retraction control unit 1311 controls the radial direction restriction mechanism 1121 to place the inspection device 110 in a tensioned state between the outer surface of the inner container 210 and the inner surface of the outer container 220. This makes it possible to restrict radial movement of the inspection device 110, particularly radially inward movement of the inspection device 110. As a result, it is possible to prevent the inspection device 110 from falling off the guide 120.

[0080] Next, the origin return control unit 1312 executes origin return processing S102, which controls the movement of the inspection device 110 to an inspection start position. In the origin return processing S102, the origin return control unit 1312 controls the traveling mechanism 1110 to cause the inspection device 110 to travel in the circumferential direction. The origin return control unit 1312 also detects an index 123 indicating a reference position provided on the guide 120 using a reference position detection sensor of the position control mechanism 1111. The origin return control unit 1312 identifies the position of the inspection device 110 in the pressure vessel 200 based on position information linked to the position (reference position) where the index 123 is detected, and then controls the movement of the inspection device 110 to the inspection start position.

[0081] Next, the control unit 131 executes an inspection process S103 for inspecting the inspection target. When performing an ultrasonic flaw detection inspection on the welded joint 212, in the inspection process S103, the control unit 131 controls the transmitting unit of the inspection unit 114 to transmit ultrasonic waves from the transmitting unit toward the welded joint 212. The receiving unit of the inspection unit 114 receives ultrasonic waves reflected by the welded joint 212. The scanning unit 1313 of the control unit 131 also controls the sliding mechanism of the second support 1130 to move the inspection unit 114 in the vertical direction. In the inspection process S103, this series of operations of transmitting and receiving ultrasonic waves in the inspection unit 114 and moving the inspection unit 114 in the vertical direction is repeated across the entire width of the welded joint 212 in the vertical direction.

[0082] Furthermore, in the inspection process S103, the inspection unit 114 transmits the inspection results to the abnormality determination unit 1314. For example, the inspection unit 114 may transmit the inspection results to the abnormality determination unit 1314 each time a series of operations, including transmitting and receiving ultrasonic waves to and from the welded joint 212 and moving the inspection unit 114 in the vertical direction, is completed. Alternatively, the inspection unit 114 may transmit the inspection results to the abnormality determination unit 1314 all at once after a series of operations, including transmitting and receiving ultrasonic waves to and from the welded joint 212 and moving the inspection unit 114 in the vertical direction, is repeated over the entire vertical width of the welded joint 212. Alternatively, the inspection unit 114 may transmit the inspection results to the abnormality determination unit 1314 at an appropriate time when transmitting and receiving ultrasonic waves to and from the welded joint 212 or when the inspection unit 114 moves in the vertical direction.

[0083] Next, the abnormality determination unit 1314 executes an abnormality determination process S104 for determining whether or not an abnormality exists in the test object based on the test results received from the inspection unit 114. In the abnormality determination process S104, the abnormality determination unit 1314 determines whether or not an abnormality exists in the test object by comparing the test results received from the inspection unit with normal test results pre-stored in the storage unit 134. If the abnormality determination unit 1314 determines that an abnormality exists in the test object (YES in S104), the process proceeds to a notification process S105. On the other hand, if the abnormality determination unit 1314 determines that no abnormality exists in the test results (NO in S104), the process proceeds to an end determination process S106.

[0084] In the present disclosure, the abnormality determination unit 1314 determines whether or not an abnormality exists in the test result based on a comparison with the test result under normal conditions, but is not limited to this. For example, the abnormality determination unit 1314 may determine that an abnormality exists in the test object when the test result received from the test unit 114 indicates an abnormal value.

[0085] In the present disclosure, an example has been given in which the abnormality determination unit 1314 determines whether or not there is an abnormality in the inspection object based on the inspection results received from the inspection unit 114, but the present disclosure is not limited to this. For example, a person may determine whether or not there is an abnormality in the inspection object based on the inspection results received from the inspection unit 114 instead of the abnormality determination unit 1314. Here, specific examples of a person who determines whether or not there is an abnormality in the inspection object include a worker, a manager of the pressure vessel 200, etc.

[0086] If it is determined that the inspection object has an abnormality (YES in S104), the control unit 131 executes notification processing S105 to notify the operator or the manager of the pressure vessel 200 of this fact. In the notification processing S105, the control unit 131 displays on the display unit 133 a display image indicating that the inspection object has been determined to have an abnormality.

[0087] Here, the control unit 131 may identify the position where the abnormality is determined in the inspection object. For example, the control unit 131 identifies the position where the abnormality is determined in the inspection object using an encoder. In this case, the control device 130 identifies the position where the abnormality is determined in the inspection object by combining information indicating the amount of movement from the inspection start position detected by the encoder to the position where the inspection result indicating the abnormality was obtained and position information of the inspection start position pre-stored in the memory unit 134. The control unit 131 may notify the operator or the manager of the pressure vessel 200 of the position information of the position where the abnormality is determined, along with the fact that the inspection object has been determined to have an abnormality. This allows the operator or the manager of the pressure vessel 200 to understand the position where the abnormality is determined. The control unit 131 stores the position information of the position where the abnormality is determined in the inspection object in the memory unit 134 in association with the inspection result or the inspection time that originally made the determination.

[0088] Next, the control unit 131 executes a completion determination process S106 to determine whether or not the inspection of the predetermined inspection range has been completed. As a result, if it is determined that the inspection of the inspection range has not been completed (NO in S106), the process proceeds to a transfer process S107. On the other hand, if it is determined that the inspection of the inspection range has been completed (YES in S106), the process proceeds to a collection process S108.

[0089] If the travel control unit 1310 determines that the inspection of the inspection range has not been completed (NO in S106), it executes a movement process S107 in which the inspection device 110 moves in the circumferential direction. In the movement process S107, the travel control unit 1310 controls the travel mechanism 1110 to move the inspection device 110 from the first position where the inspection process S103 was executed to a second position. The second position is a position different from the first position and is a position moved from the first position in the circumferential direction of the pressure vessel 200. Then, the process returns to the inspection process S103.

[0090] When the arm extension / retraction control unit 1311 and the transporting device 140 determine that inspection of the inspection range has been completed (YES in S106), they execute a recovery process S108 to recover the inspection device 110 from the pressure vessel 200. In the recovery process S108, the arm extension / retraction control unit 1311 stops the operation of the radial direction limiting mechanism 1121 and releases the restriction on the radial movement of the inspection device 110. The transporting device 140 lifts the inspection device 110 up to the opening 221 by reeling in the cable or dedicated wire connecting the inspection device 110 and the control device 130, and recovers the inspection device 110 from the opening 221. This completes the processing of the inspection method.

[0091] As described above, the inspection system 100 according to the present disclosure includes the inspection device 110. The inspection device 110 inspects the weld joint 212 of the inner container 210 while traveling along the inner surface of the outer container 220 in contact with the vertical upper surface of the guide 120 that extends along the inner surface of the outer container 220.

[0092] In the inspection system 100 according to the present disclosure, the inspection device 110 is configured to inspect the weld joint 212 of the inner vessel 210 while traveling along the inner surface of the outer vessel 220 while in contact with the vertical upper surface of a guide 120 provided on the inner surface of the outer vessel 220. As a result, the inspection device 110 is not engaged with the guide 120, and therefore the inspection device 110 can be easily positioned in the pressure vessel 200 by remote control. Furthermore, because the guide 120 limits the vertical downward movement of the inspection device 110, the inspection device 110 can travel horizontally along the weld joint 212 without being affected by gravity.

[0093] A modified example of the inspection device 110 (hereinafter referred to as "inspection device 110a") will be described with reference to Fig. 8. Fig. 8 is a perspective view illustrating the configuration of the inspection device 110a. For ease of explanation, members having the same functions as those described in the inspection device 110 above will be denoted by the same reference numerals, and their description will not be repeated.

[0094] As shown in Fig. 8, the inspection device 110a differs from the inspection device 110 in that a plate-like member 1110b is provided on a wheel 1110a. The plate-like member 1110b is provided on the vertical lower surface of the wheel 1110a, which is provided on the vertical lower surface of the main body 111. The length of the plate-like member 1110b is not particularly limited, but it is preferably long enough so that the gap 121 does not interfere with the circumferential movement of the pressure vessel 200 in the inspection device 110a. For example, the length of the plate-like member 1110b is longer than the length L of the gap 121.

[0095] Although the embodiments of the present disclosure have been described above with reference to the accompanying drawings, it goes without saying that the present disclosure is not limited to such embodiments. It is clear that a person skilled in the art can conceive of various modifications and alterations within the scope of the claims, and it is understood that such modifications and alterations also fall within the technical scope of the present disclosure.

[0096] The present disclosure can contribute, for example, to Sustainable Development Goal (SDG) Goal 7 "Ensure access to affordable, reliable, sustainable and modern energy" and Goal 13 "Take urgent action to combat climate change and its impacts."

[0097] 100: Inspection system 110: Inspection device 111: Main body 112: First arm (arm) 1121: Radial direction limiting mechanism 113: Second arm (arm) 114: Inspection unit 120: Guide 121: Gap 122: Recessed portion 123: Index 130: Control device 131: Control unit 200: Pressure vessel

Claims

1. An inspection device that is placed between an inner container and an outer container in a double container in which portions of the inner and outer containers are cylindrical, and that comprises: an inspection unit that inspects the inner container; a main body that is provided with wheels so that it can move; and an arm that has a radial restriction mechanism that restricts the radial movement of the double container on the main body, and that runs circumferentially around the inner surface of the outer container with one of the surfaces of the main body in contact with the vertical upper surface of a guide that extends circumferentially around the outer container.

2. The inspection device according to claim 1, wherein the arms include a first arm extending from the main body in the radial direction of the inner container, and a second arm connected to the first arm, on which the inspection unit is provided so as to be movable in the vertical direction.

3. The inspection device according to claim 2, wherein the first arm restricts the radial movement of the main body by pressing the second arm against the outer surface of the inner container.

4. The inspection device according to claim 2, wherein the first arm includes an elastic body, and the restriction on radial movement of the main body is released by the elastic force of the elastic body.

5. An inspection device according to claim 1, further comprising a position control mechanism that controls the inspection device to a start position for inspection, wherein the position control mechanism detects an index indicating a reference position provided on the guide, and identifies the reference position as the position of the inspection device in the double container.

6. The inspection device according to claim 1, wherein the guide is provided with at least one gap, and the gap has a length that does not interfere with the circumferential movement of the inspection device.

7. An inspection system comprising: the inspection device according to any one of claims 1 to 6; the guide extending in the circumferential direction of the outer container; and a control device that controls the movement of the inspection device.

8. An inspection method using an inspection device for a double container in which a portion of the inner container and a portion of the outer container are cylindrical, the inspection device comprising: an inspection unit that is positioned between the inner container and the outer container and inspects the inner container; a main body with wheels that allows it to move; and an arm with a radial restriction mechanism that restricts radial movement of the double container on the main body, the inspection method including the steps of: suspending the inspection device and positioning it so that one surface of the main body is in contact with the vertical upper surface of a guide that extends circumferentially of the outer container; restricting the radial movement of the inspection device by operating the radial restriction mechanism; traveling the inspection device in the circumferential direction by driving the wheels; inspecting the inner container; and stopping the radial restriction mechanism and hoisting the inspection device.

9. The inspection method according to claim 8, wherein, when said inspection device is in contact with said guide, vertical downward movement is restricted, but vertical upward movement is not restricted.

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