JP7186051B2 - ultrasonic inspection equipment - Google Patents

Description

The present invention relates to an ultrasonic inspection apparatus.

Component maintenance in power plants is necessary to maintain normal operation. Therefore, the role played by non-destructive inspection technology is highly important. Especially in a nuclear power plant, it is important to ensure the soundness of reactor primary system equipment such as a reactor pressure vessel (RPV) and recirculation system piping. Therefore, according to the standards, ultrasonic flaw detection (UT) is required as a volumetric inspection for confirming the secular change of equipment, piping, etc. during the service period.

For example, a nozzle (pipe stub) 103 that connects the reactor pressure vessel 101 and the pipe 102 shown in FIG. 8 is subject to pre-service inspection (PSI) and in-service inspection (ISI).

FIG. 9A shows axial cross sections (xz cross section and yz cross section) of the nozzle 103 . In FIG. 9A, the xz section is indicated by a solid line, and the yz section is indicated by a two-dot chain line. FIG. 9B shows the positional relationship between the inspection range 108 of the nozzle 103 and the outer surface R portion 104 when viewed from the direction of the axis C0 of the nozzle 103 .
An outer surface R portion 104 , a cylindrical portion 105 and an inclined portion 106 are formed on the outer surface of the nozzle 103 . The outer surface R portion 104 is a boundary portion between the reactor pressure vessel 101 and the nozzle 103 . The cylindrical portion 105 is the main body of the nozzle 103 . An inclined portion 106 is a boundary portion between the nozzle 103 and the pipe 102 .

An inner surface R portion 107 of a nozzle corner portion is formed on the inner surface of the nozzle 103 . An inspection range 108 of the nozzle 103 is an area HIJK (hatched portion in FIG. 9A ) on the inner surface side of the nozzle 103 , including the inner surface R portion 107 and a portion corresponding to the plate thickness of the reactor pressure vessel 101 . 9B shows the positional relationship between the inspection range 108 and the outer surface R portion 104 when viewed from the direction of the axis C0 of the nozzle 103. As shown in FIG. In FIG. 9B, the inspection range 108 is indicated by hatching, and the outer surface R portion 104 is indicated by dots.

The outer surface R portion 104 and the inner surface R portion 107 of the nozzle 103 are complicated three-dimensional curved surface shapes, more specifically curved surface portions having curvatures in the circumferential direction and the axis C0 direction of the nozzle 103 . Therefore, as shown in FIG. 9A, the shape of the axial cross-section of the nozzle 103 changes according to the position of the ultrasonic probe in the circumferential direction of the nozzle 103, and the surface method that determines the direction of incidence and the direction of reflection of ultrasonic waves. The line direction changes greatly depending on the position. The change in shape is particularly large in the direction of the axis C0 of the nozzle 103 in the horizontal direction in FIG. 9A.

10A and 10B are schematic diagrams showing inspection by a conventional ultrasonic inspection apparatus.
FIG. 10A is an image diagram of a state in which an ultrasonic probe 100 is attached to the outer surface of a conventional nozzle, viewed from the side. FIG. 10B is a schematic diagram for explaining the trajectory and probe holding mechanism of the conventional ultrasonic probe 100, and is an enlarged view showing the state of the apparatus when inspecting the YZ cross section.
When inspecting the inspection range 108 of the nozzle 103, generally, the ultrasonic probe 100 is installed on the outer surface R portion 104 of the nozzle 103 as shown in FIGS. 10A and 10B. Then, the ultrasonic probe 100 is scanned in the circumferential direction and the axis C0 direction of the nozzle 103 so as to follow the shape of the outer surface R portion 104 of the nozzle 103, and ultrasonic waves are transmitted from the ultrasonic probe 100.

At this time, for example, the ultrasonic waves are incident so that the axial cross section of the nozzle 103 has a refraction angle of 0 degree and the radial cross section of the nozzle 103 has a refraction angle of θ. Then, the ultrasound probe 1 receives an echo (reflected wave) from a defect of the nozzle 103 , more specifically, a crack, hole, or the like.

However, since this method propagates ultrasonic waves from one complicated curved surface to another complicated curved surface, the ultrasonic wave propagation path varies greatly depending on the position and direction of the defect. It is limited to axial cracks present near the center of the roundness of portion 107 (the point at 45° in the radial direction).

On the other hand, if it is possible to access from the inner surface of the nozzle 103, there is also a method in which the ultrasonic probe 100 for surface inspection is installed directly on the inner surface R portion 107 of the inspection range 108 and the inner cylindrical surface of the nozzle 103. Scanning is performed by changing the direction of the probe 100 according to the direction of the assumed crack. For example, the probe 100 is directed in the circumferential direction for axial cracks and in the axial direction for circumferential cracks. As a result, the probe 100 allows the ultrasonic beam to be incident from the direction directly facing the surface of the crack at all times, so high detection sensitivity can be expected.

For example, in Patent Document 1, as an ultrasonic inspection device for inspecting the inner surface R portion from the inner surface side of the nozzle, a device is proposed in which the jig side is deformed according to the inner surface shape that changes intricately, so that the probe is brought into close contact. there is

Japanese Patent Application Laid-Open No. 10-90233 (FIGS. 91 to 1, paragraphs 0007 to 0014) Japanese Patent No. 2637553

By the way, the device described in Patent Document 1 is premised on the use of a plurality of probes (3) (Fig. 1 of Patent Document 1), and uses an air chamber (41) and an elastic wall (43) as a deformation mechanism. It is a large-scale device and is expensive. Moreover, as described above, the inner surface R portion is a complicated curved surface having curvatures in two directions, the circumferential direction and the axial direction. Therefore, it is difficult to always stabilize the posture of the probe (3) in the method of simply pressing the probe (3) to follow the surface. Since the posture of the probe (3) directly affects the propagation direction of the ultrasonic waves, there is concern from the viewpoint of ensuring the reliability of inspection.

Therefore, in order to scan the probe in a stable posture with respect to the inner surface R of the nozzle while keeping costs down with a relatively simple mechanism, it is necessary to take measures against the surface curvature that changes greatly depending on the difference in the inspection position. be. Since the curvature in the circumferential direction is a negative value when viewed from the probe installed on the inner surface, that is, the surface is concave, unless a wedge with a curvature larger than the maximum curvature of the inner surface is installed on the probe, the ultrasonic wave incident point The probe center becomes floating from the inner surface.

However, the circumferential curvature of the inner surface varies greatly depending on the axial position of the pipe. For example, as shown in FIG. 9A, the curvature is maximum on the 0° side of the inner surface R of the nozzle and minimum on the 90° side. However, when it approaches the inner surface of the reactor pressure vessel, point contact occurs, and simply pressing the probe makes the posture of the probe unstable.

As an example of a device for stabilizing the posture of the probe, there is a device described in Patent Document 2. As shown in FIG. 4 of Patent Document 2, there are rails that match the cross-sectional shape of the inner surface of the nozzle vertically upward (0° direction in FIG. 8) and horizontally left (270° direction in FIG. 8) in the nozzle circumferential direction. is doing.

A probe (sensor) holding device (30) that elastically holds the probe along the rails (26, 27) moves in the axial direction while rotating the rails (26, 27) in the circumferential direction. By doing so, there is also a device that scans the probe with respect to the nozzle inner surface R portion (nozzle opening portion 14). This device aligns the axis of the ultrasonic probe with the normal line of the nozzle inner surface R (nozzle opening 14) at the inspection target position in the 0°, 180°, 90°, and 270° directions. be able to.

Therefore, although the probe is stabilized, it is necessary to manually adjust the axial position of the rail and the like for other azimuths, which complicates the operation. Moreover, since the apparatus is specialized for one type of nozzle shape, at least the same rail cannot be used for nozzles of different sizes.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an ultrasonic inspection apparatus that realizes stable and highly accurate probe scanning on a complicated curved surface without the need for fine control.

In order to solve the above-mentioned problems, the ultrasonic inspection apparatus of the present invention includes: a rotating shaft arranged to rotate about a center line of a small cylindrical body projecting from the side surface of the large cylindrical body; In contrast, a track including an arc-shaped portion that is slidable in the axial direction of the small cylinder, and a track that is attached to the track and contacts the inner surface of the large cylinder, when the track rotates in the circumferential direction of the small cylinder , a tracing mechanism for maintaining a constant distance between the inner surface of the large cylinder and the inner surface of the small cylinder or the R portion of the inner surface of the small cylinder; a probe holding mechanism that moves along the track; An ultrasonic probe elastically supported in the axial direction by a probe holding mechanism, and a moving mechanism for moving the track in the axial direction of the small cylindrical body , wherein the track and the central axis of the rotation shaft and a track position adjusting mechanism for adjusting the distance between them in the radial direction of the small cylinder .

According to the present invention, it is possible to provide an ultrasonic inspection apparatus that realizes stable and highly accurate probe scanning on a complicated curved surface without the need for fine control.

FIG. 9 is a diagram showing an XZ cross section in directions of 0° and 180° in FIG. 8 of the ultrasonic inspection apparatus of the embodiment; FIG. 9 is a diagram showing the state of the ultrasonic inspection apparatus according to the embodiment when inspecting YZ cross sections in the directions of 90° and 270° in FIG. 8 ; FIG. 4 is a view of a bearing mechanism with a reduced pitch diameter viewed axially; The figure of the bearing mechanism which expanded the pitch circle diameter which looked at the axial direction. FIG. 4 is a schematic diagram showing a drive unit of a rotating mechanism of a rotating shaft; FIG. 1B is an enlarged view of part of FIG. 1B showing the state of the ultrasonic inspection apparatus when inspecting the YZ cross section; FIG. 2 is a schematic cross-sectional view showing the structure of a probe holding mechanism that holds an ultrasonic probe; The I direction arrow directional view of FIG. 5A. Schematic diagram showing an example of a track position adjustment mechanism and an offset adjustment mechanism. II-II sectional view of FIG. 6A. The cross-sectional schematic diagram which shows the ultrasonic inspection apparatus of a modification. The perspective view which shows the nozzle (nozzle) which connects a reactor pressure vessel and piping. The figure which shows the axial direction cross section (xz cross section and yz cross section) of a nozzle. FIG. 5 is a view showing the positional relationship between the inspection range and the outer surface R portion when viewed from the axial direction of the nozzle; An image diagram of a state in which an ultrasonic probe is attached to the outer surface of a conventional nozzle, viewed from the side. FIG. 4 is a schematic diagram for explaining the trajectory of a conventional ultrasonic probe and a probe holding mechanism, and is an enlarged view showing the state of the apparatus when inspecting the YZ cross section.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings as appropriate.
The present invention relates to an ultrasonic inspection apparatus suitable for ultrasonic inspection of R portions of the inner surfaces of nozzles of pressure vessels and pipes in power plants, particularly nuclear power plants.

The nozzle 103 (see FIG. 8) described above will be described as an example of an inspection object of the embodiment. 8, 9A, and 9B described above also apply to the present embodiment, and are appropriately used for explanation.

FIGS. 1A and 1B are schematic diagrams showing the structure of an ultrasonic inspection apparatus E according to the embodiment, and are image views of a state in which the apparatus (E) is attached to the inner surface of the nozzle 103 as viewed from the side. FIG. 1A shows the XZ cross section in the 0° and 180° directions in FIG. 8, and FIG. 1B shows the state of the apparatus (E) when inspecting the YZ cross section in the 90° and 270° directions in FIG. FIGS. 1A and 1B illustrate a case in which the ultrasonic probe 1 is moved to the 45° azimuth of the nozzle inner surface R portion 107 as a representative.

The ultrasonic inspection apparatus E includes a bearing mechanism 260 , a rotating shaft 200 , a track 201 , a copying mechanism 202 , a probe holding mechanism 203 and an ultrasonic probe 1 .
The ultrasonic inspection apparatus E is arranged such that the nozzle inner surface 103a is aligned with the central axis C0 of the nozzle 103 projecting from the side surface of the body portion 101 of the reactor pressure vessel (hereinafter referred to as RPV) and connecting the pipe 102. A bearing mechanism 260 is installed so as to be in close contact with the .

The rotary shaft 200 is inserted into the bearing mechanism 260 and arranged to rotate in the circumferential direction of the nozzle 103 .
A guide rail 200 b that holds the track 201 is attached to the rotating shaft 200 .

The track 201 includes an arc-shaped portion 201a held so as to be slidable in the direction of the axis C0 of the nozzle 103 along the guide rail 200b.
The copying mechanism 202 has a copying roller 202 r that is attached to the track 201 and used in contact with the RPV inner surface 101 a or the nozzle inner surface R portion 107 . The copying mechanism 202 has a role of keeping the distance between the RPV inner surface 101a or the nozzle inner surface R portion 107 and the rotating shaft 200 constant.

The probe holding mechanism 203 holds the ultrasonic probe 1 . The ultrasonic probe 1 oscillates ultrasonic waves and receives reflected ultrasonic waves. The probe holding mechanism 203 moves in the direction of the axis C0 of the nozzle 103 along the track 201 by the moving mechanism 203M (see FIG. 5A).

The ultrasonic probe 1 is pushed by a pressing shaft 310 (see FIG. 5A), which is provided in the probe holding mechanism 203 and faces in a direction perpendicular to the track 201, such as a spring, a pneumatic cylinder, or a hydraulic cylinder. The probe 1 is elastically held in the axial direction. That is, the ultrasonic probe 1 is pressed against the nozzle inner surface R portion 107 by the pressing shaft 310 oriented in a direction perpendicular to the track 201 .

<Bearing mechanism 260>
2A and 2B show an example of a bearing mechanism 260 with a variable pitch diameter. 2A is a view of the bearing mechanism 260 with a reduced pitch diameter viewed in the direction of the axis C0, and FIG. 2B is a view of the bearing mechanism 260 with an enlarged pitch diameter viewed in the axial direction.

The bearing mechanism 260 has a plurality of pressing pads 261 pressed against the nozzle inner surface 103a.
The bearing mechanism 260 is a variable mechanism having a structure capable of changing the pitch circle diameter of the arrangement of the plurality of pressing pads 261 . As a result, the bearing mechanism 260 can be easily inserted into the nozzle inner surface 103a and closely attached, and the same device can be applied to nozzles 103 of various sizes.

The bearing mechanism 260 has a plurality of pressing pads 261, a plurality of pad support arms 262, a variable guide ring 264, and a support disc 260b.
A rotation bearing hole 260a is opened in the center of the supporting disk 260b. A rotation center shaft 200j coaxially connected to the rotation shaft 200 is inserted into the rotation bearing hole 260a.

A plurality of support pins 260b1 are installed on the support disk 260b. One end of the pad support arm 262 is rotatably supported by the support pin 260b1.
A variable guide ring 264 is provided on the outer periphery of the support disc 260b so as to be rotatable relative to the support disc 260b. The inner diameter of the variable guide ring 264 is slightly larger than the outer diameter of the support disc 260b, and the variable guide ring 264 rotates smoothly around the support disc 260b.

The variable guide ring 264 is provided with the same number of ring pins 264 a as the pad support arms 262 .
A plurality of pressing pads 261 are annularly arranged outside the outer circumference of the variable guide ring 264 .

A pad pin 261 p that supports the pad support arm 262 is installed on the pressing pad 261 . An inter-pad plate 263 is arranged between adjacent pressing pads 261 to rotatably support each other. The inter-pad plate 263 rotatably connects adjacent pressing pads 261 .

A plurality of pad support arms 262 are provided between the support disc 260b, the variable guide ring 264 and the plurality of pressing pads 261 to rotatably connect them.
The pad support arm 262 has an elongated hole 262a in the center and holes 262b and 262c at both ends.

A ring pin 264a of a variable guide ring 264 is slidably fitted into the elongated hole 262a of the pad support arm 262. As shown in FIG.
A support pin 260b1 of a support disk 260b is fitted into a hole 262b at one end of the pad support arm 262, and the one end of the pad support arm 262 is rotatably supported by the support pin 260b1.

A pad pin 261p of the pressing pad 261 is fitted into a hole 262c at the other end of the pad support arm 262, and the other end of the pad support arm 262 is rotatably supported by the pad pin 261p.
In the bearing mechanism 260 described above, as shown in FIG. 2A, by rotating the variable guide ring 264 in the counterclockwise direction (arrow α1 direction), the positions of the plurality of pad support arms 262 are changed, and the plurality of pressing arms 262 are changed. The pitch diameter of the pad 261 arrangement can be reduced.

On the other hand, as shown in FIG. 2B, by rotating the variable guide ring 264 of the bearing mechanism 260 in the clockwise direction (direction of arrow α2), the positions of the plurality of pad support arms 262 are changed and the plurality of pressing pads 261 are moved. The pitch circle diameter of the arrangement can be enlarged.

Due to the bearing mechanism 260 described above, even if the nozzle 103 is changed, the pitch circle diameter of the arrangement of the pressing pads 261 can be changed and the same ultrasonic inspection apparatus E can be applied.
Note that the bearing mechanism 260 may have a configuration other than the above as long as the pitch circle diameter of the arrangement of the pressing pads 261 can be reduced or enlarged. For example, a configuration may be adopted in which an external force is applied radially outward to the plurality of pad support arms 262 and the external force is controlled.

As shown in FIGS. 1A and 1B, in the ultrasonic inspection apparatus E, magnet holders 269a and 269b having a shape matching the shape of the RPV inner surface 101a are fixed on the opposite side of the rotating shaft 200 from the bearing mechanism 260. A frame 269 is installed. By bringing the magnet holders 269 a and 269 b into close contact with the RPV inner surface 101 a , the inclination of the rotating shaft 200 with respect to the RPV inner surface 101 a can be suppressed, and the axis of the rotating shaft 200 can be aligned with the central axis of the nozzle 103 .

A rotating shaft 200 that supports the bearing mechanism 260, the ultrasonic probe 1, the probe holding mechanism 203, the track 201, and the copying mechanism 202, and magnet holders 269a and 269b are fixed to the stationary frame 269. . Therefore, the fixed frame 269 also plays a role of supporting the weight of the entire device.

<Rotating Mechanism of Rotating Shaft 200>
FIG. 3 is a schematic diagram showing a drive unit 280 that is a rotating mechanism for rotating shaft 200. As shown in FIG.
The rotary shaft 200 is rotatably supported by a fixed frame 269 via a concentric support shaft 200s. A rotary shaft pinion 284 is fixed to the end of the support shaft 200s.

The rotary shaft 200 is rotationally driven by the drive unit 280 via the rotary shaft pinion 284 and the support shaft 200s.
In other words, the rotation shaft 200 receives power from a motor 281 inside a drive unit 280 attached to the outside of the fixed frame 269 via gears 282b, timing belts, etc. rotate in the direction

The drive unit 280 has a motor 281, a gearbox 282, an encoder 283, gears 282b, and the like.
The rotation of the motor 281 is decelerated by various gears 282 a in the gear box 282 and transmitted to the gear 282 b meshing with the rotating shaft pinion 284 . The rotation of the gear 282b is acquired by the encoder 283, and the rotational speed of the rotary shaft 200 can be grasped.

With this configuration, the rotation of the rotating shaft 200 is controlled at a desired rotation speed by the rotation of the motor 281 .
By rotating the rotating shaft 200 with the drive unit 280, the ultrasonic probe 1 can be rotated in the circumferential direction of the nozzle 103, and the nozzle inner surface R portion 107 can be measured in the circumferential direction.

<Track 201 and probe holding mechanism 203>
FIG. 4 shows the state of the ultrasonic inspection apparatus E when inspecting the YZ cross section, and is an enlarged view of part of FIG. 1B.
The track 201 and probe holding mechanism 203 will be described in detail.

The trajectory 201 is designed according to the surface shape of the inspection range 108 (see FIG. 1A) on the nozzle inner surface 103a. That is, the trajectory 201 has a linear trajectory and an arc trajectory (central angle of approximately 90°) in accordance with the linear cross-sectional contour (103a) on the nozzle inner surface 103a side and the circular arc-shaped cross-sectional contour on the RPV (RPV inner surface 101a) side. It is a structure that combines As a result, the center of curvature of the arc-shaped portion 201a of the track 201 and the center of curvature C of the nozzle inner surface R portion 107 (see FIG. 4) are made to coincide.

A probe holding mechanism 203 is attached to the nozzle inner surface 103 a side inside the track 201 .

<Probe holding mechanism 203>
5A is a schematic cross-sectional view showing the structure of the probe holding mechanism 203 that holds the ultrasound probe 1, and FIG. 5B is a view taken in the direction of arrow I in FIG. 5A.
The probe holding mechanism 203 has a traveling carriage 203a on which the pressing shaft 310 is mounted. The traveling carriage 203 a travels along the track 201 .

The probe holding mechanism 203 has a moving mechanism 203M. The moving mechanism 203M has a rack 301, a pinion 302, a motor 303, and an encoder 304.
The rack 301 is formed on the inner bottom plate 201s of the track 201 along the extending direction of the track 201 (the direction of the front and back surfaces of the paper surface of FIG. 5A).

A pinion 302 meshes with the rack 301 .
The pinion 302 is connected to a motor 303 via gears of a gearbox 305 housing a reduction mechanism.

The amount of rotation of pinion 302 is detected by encoder 304 provided coaxially with pinion 302 .
The pressing shaft 310 is formed by an air cylinder. The pressing shaft 310 has a cylinder 310a and a piston 310b.

One end of the piston 310b is housed inside the cylinder 310a.
Air is supplied from an air supply tube 311 to the cylinder 310a. The piston 310b protrudes from the cylinder 310a or is housed in the cylinder 310a according to an increase or decrease in the amount of air in the cylinder 310a.

A probe rotation mechanism 320 that rotates the ultrasound probe 1 around the axis C1 is fixed to the other end of the piston 310b. A probe rotation shaft 320a is provided to rotate around. A motor (not shown) is provided in the probe rotation mechanism 320, and the rotation of the motor is transmitted to the rotation of the probe rotation shaft 320a. For example, a motor may rotate the probe rotating shaft 320a by direct drive, or may rotate it via a reduction mechanism.

The probe holder 321 supports the ultrasonic probe 1 that oscillates ultrasonic waves and receives reflected ultrasonic waves.

<Ultrasonic probe 1>
A wedge 1a (see FIG. 5A) is installed at the tip of the ultrasonic probe 1 to keep contact with the inner surface of the object (the nozzle inner surface 103a and the nozzle inner surface R portion 107 in FIG. 4). By driving the motor of the probe rotation mechanism 320, the ultrasonic probe 1 on which the wedge 1a is installed is rotated via the probe holder 321 as shown in FIG. α21 direction). By rotating the ultrasonic probe 1, cracks in all directions of 360° can be measured. For example, cracks in the direction of the axis C0 of the nozzle 103 (see FIG. 4) or in the circumferential direction of the nozzle 103 can be measured.

By extending the pressing shaft 310, the wedge 1a of the probe 1 is brought into contact with the subject inner surface hn as indicated by the two-dot chain line in FIG. and the axis C1 of the probe 1 and the probe holding mechanism 203 are made to coincide with each other.

Then, an ultrasonic beam b0 is oscillated from the probe 1 to the inner surface hn of the subject through the contact portion 1a0 of the wedge 1a. Therefore, the contact portion 1a0 of the axis C1 on the contact surface 1a1 of the wedge 1a needs to be in contact with the inner surface hn of the subject. Therefore, the curvature of the contact surface 1a1 of the wedge 1a has a curvature equal to or greater than the maximum curvature of the subject inner surface hn.

To measure the inner surface 102a of the pipe 102, a wedge 1a having the same curvature as the inner surface 102a of the pipe 102 is attached. As a result, the inner surface 102a of the pipe 102 can be accurately measured using the ultrasonic probe 1. FIG.
With the above configuration, the pinion 302 engages with the rack 301 of the track 201 and rotates, thereby moving the probe holding mechanism 203 along the track 201 (horizontal direction in FIG. 4).

At this time, the probe holding mechanism 203 is restrained by the side shape of the track 201, and the direction of the axis C1 of the probe holding mechanism 203 is always perpendicular to the bottom plate 201s of the track 201 (see FIG. 5A). It is designed to face As the probe holding mechanism 203 moves along the track 201, the ultrasonic probe 1 pressed against the inner surface 103a of the nozzle by the pressing shaft 310 of the probe holding mechanism 203 moves into the inspection range 108 (see FIG. 4). ) in the direction of the nozzle axis C0. Then, ultrasonic waves are oscillated from the probe 1 to the nozzle inner surface R portion 107 and the nozzle inner surface 103a through the wedge 1a.

Here, the moving mechanism 203M (see FIG. 5A) of the probe holding mechanism 203 by the rack 301 and the pinion 302 is illustrated, but the probe holding mechanism 203 is moved from the outside of the probe holding mechanism 203 by a timing belt, a chain, or the like. A structure that transmits the driving force to 203 may be used.

Further, as described above, the probe holding mechanism 203 is provided with a probe that allows the orientation of the ultrasonic probe 1 to rotate about the axis of the probe holding mechanism 203 as the central axis C1 (arrow α21 in FIG. 5B). If the child rotation mechanism 320 is provided, it is possible to inspect cracks in various directions, such as axial cracks, circumferential cracks, and cracks occurring in intermediate directions, without replacing the ultrasonic probe 1 . In addition, the axial crack refers to a crack extending in the direction of the nozzle axis C0 (horizontal direction in FIG. 4). On the other hand, a circumferential crack refers to a crack extending in the circumferential direction of the nozzle 103 .

<Track 201>
The track 201 shown in FIG. 4 is elastically held in the direction of the nozzle axis C0 (to the left in FIG. 4) by a pressing mechanism 200c (specifically, a spring, pneumatic cylinder, or hydraulic cylinder, for example) of the rotating shaft 200. It is

The track 201 is slidable in the direction of the nozzle axis C0 along the guide rail 200b. As the rotary shaft 200 rotates, the copying roller 202r at the tip of the copying mechanism 202 attached to both sides of the arc-shaped portion 201a of the track 201 comes into contact with the RPV inner surface 101a or the nozzle inner surface R portion 107, and the RPV inner surface 101a or It follows the shape change of the nozzle inner surface R portion 107 .

As a result, the track 201 automatically slides in the direction of the nozzle axis C0. A two-dot chain line portion indicated by reference numeral 201 in FIG. 4 represents the position of the track 201 during the XZ cross-sectional inspection in the RPV vertical direction. When inspecting the YZ cross section in the horizontal direction of the RPV with the ultrasonic inspection apparatus E, it slides toward the center of the RPV (to the right in FIG. 4) as shown.

The arc-shaped portion 201 a of the track 201 is an arc-shaped track with a central angle of slightly more than 90° and a constant curvature radius larger than the axial curvature radius of the nozzle inner surface R portion 107 . The mounting position of the track 201 with respect to the rotating shaft 200 can be finely adjusted by two position adjustment axes.

The guide rail 200b is provided with a track position adjusting mechanism 300 (see FIG. 6A) for adjustment in the vertical direction in FIG. 4 and an offset adjustment mechanism 202b for adjustment in the horizontal direction in FIG. 6A.
The track position adjustment mechanism 300 adjusts the mounting position of the track 201 in the radial direction of the nozzle (vertical direction in FIG. 4).

The offset adjusting mechanism 202 b adjusts the distance from the track 201 to the copying roller 202 r at the tip of the copying mechanism 202 attached to the track 201 .

<Track position adjustment mechanism 300>
FIG. 6A is a schematic diagram showing an example of the track position adjusting mechanism 300 and the offset adjusting mechanism 202b, and FIG. 6B is a cross-sectional view taken along line II-II in FIG. 6A.
The track position adjustment mechanism 300 has the following configuration.

The rotating shaft 200 is provided with a lift pin 302a. A rotary knob 306 to which a ball screw 305 is connected is rotatably attached to the rotating shaft 200 . The ball screw 305 is attached with a slide carriage 304 that moves in the direction in which the ball screw 305 extends as the ball screw 305 rotates. The slide carriage 304 is provided with lift pins 302b. The lift pin 302b moves in the horizontal direction in FIG. 6A with respect to the rotating shaft 200 (arrows α31a and α31b in FIG. 6A).

On the other hand, a lift pin 302c and a lift roller 303 are installed on the guide rail 200b. The lift roller 303 is provided so as to be movable in the horizontal direction of FIG. 6A (arrows α32a and α32b in FIG. 6A) and to be rotatable with respect to the guide rail 200b.

One end of the first lift arm 301a is rotatably connected to the lift pin 302a of the rotary shaft 200, and the lift roller 303 is rotatably connected to the other end of the first lift arm 301a.
One end of the second lift arm 301b is rotatably connected to the lift pin 302c of the guide rail 200b, and the other end of the second lift arm 301b is rotatably connected to the lift pin 302b of the slide carriage 304. there is

The first lift arm 301a and the second lift arm 301b are rotatably connected to each other via a connection pin 301p at the center.
The track position adjusting mechanism 300 configured as described above rotates the rotary knob 306 to move the slide carriage 304 in the direction of the arrow α31a in FIG. 6A, thereby moving the lift roller 303 in the direction of the arrow α32a in FIG. 6A. As a result, the track 201 moves in the direction of the arrow α33a in FIG. 6A (upward direction in FIG. 6A). On the other hand, rotating the rotary knob 306 to move the slide carriage 304 in the direction of the arrow α31b in FIG. 6A causes the lift roller 303 to move in the direction of the arrow α32b in FIG. 6A. As a result, the track 201 moves in the direction of the arrow α33b in FIG. 6A (downward in FIG. 6A).

Thus, the track position adjusting mechanism 300 can adjust the distance L ₃ (see FIG. 4) of the track 201 from the center line (C0) of the rotation shaft 200 . As a result, even when the inner diameter of the inner surface of the object (the nozzle inner surface 103a and the nozzle inner surface R portion 107 in FIG. 4) changes, the distance L ₃ (see FIG. 4) from the center line (C0) of the rotation axis 200 of the track 201 ) can be adjusted without changing the trajectory 201 .

<Offset adjustment mechanism 202b of copying mechanism 202>
The copying mechanism 202 (see FIG. 1A) has the role of keeping the distance between the rotating shaft 200 in the direction of the axis C0 and the nozzle 103 constant.

The copying mechanism 202 shown in FIG. 6A has an offset adjusting mechanism 202b and a copying roller 202r rotatably supported (arrow α4 in FIG. 6A) at the tip of the offset adjusting mechanism 202b.
The offset adjustment mechanism 202b is composed of a slide fitting or the like. By changing the length of the offset adjustment mechanism 202b by sliding operation, the distance (L ₂ in FIG. 4) of the copy roller 202r from the RPV inner surface 101a or the nozzle inner surface R portion 107 can be adjusted.

For example, the length of the offset adjustment mechanism 202b can be lengthened to move the copying roller 202r (in the direction of the arrow α44a in FIG. 6A), thereby increasing the distance of the copying roller 202r from the track 201. FIG. Alternatively, the length of the offset adjustment mechanism 202b can be shortened to move the copying roller 202r (in the direction of the arrow α44b in FIG. 6A) to shorten the distance from the track 201 of the copying roller 202r.

By adjusting the orbital position adjusting mechanism 300 and the offset adjusting mechanism 202b described above, the distance L ₁ from the orbit 201 to the nozzle inner surface 103a shown in FIG. L ₃ ), and the distance L ₂ from the trajectory 201 to the RPV inner surface 101a are set appropriately.

As a result, the center of curvature of the arc-shaped portion 201 a of the orbit 201 can be aligned with the center of curvature C of the nozzle inner surface R portion 107 in the axial direction. Having two adjustment mechanisms (300, 202b) allows the same device to be applied to nozzles 103 of various sizes. Therefore, it is effective in reducing the cost of the ultrasonic inspection apparatus E and shortening the inspection time. Note that the adjustment of the distance _L1 and the distance _L2 is performed according to the following formulas.

Here, R ₀ is the inner diameter radius of the arc-shaped portion 201 a and R _f is the axial curvature radius of the nozzle inner surface R portion 107 .
Even when the surface to be inspected (in this embodiment, the nozzle inner surface R portion 107 and the nozzle inner surface 103a) is changed, the same ultrasonic inspection apparatus E can be adjusted by the trajectory position adjustment mechanism 300 and the offset adjustment mechanism 202b. can be measured.

<Mounting Position of Copying Mechanism 202>
As for the mounting position of the copying mechanism 202, as shown in FIG. 4, when the direction perpendicular to the axis of the rotation shaft 200 is 0°, the azimuth of 70° or more and less than 90° is not the 90° azimuth on the inner surface R portion 107 of the nozzle. It is better to install it in a slightly smaller azimuth (90°-α). Here, 0°<α≦20°.

The reason for this is that due to the influence of the curvature of the RPV, the orientation of the R stop of the nozzle inner surface R portion 107 (corresponding to point H in FIG. This is because the angle is smaller than 90°. In order to always match the center of curvature of the track 201 with the center of curvature C (see FIG. 4) of the nozzle inner surface R portion 107, the contact surface of the copying roller 202r should be the nozzle inner surface R portion 107 instead of the RPV inner surface 101a. desirable.

According to the above configuration, the ultrasonic probe 1 can be accurately arranged with respect to the nozzle inner surface 103 a and the nozzle inner surface R portion 107 .
Further, even if the inner surface shape of the object changes greatly as the ultrasonic probe 1 scans in the circumferential direction, as shown from I to H in FIG. Then, it automatically slides in the direction of the nozzle axis C0, keeping the distance L ₂ (see FIG. 4) constant.

Therefore, the center of curvature of the arc-shaped portion 201a is aligned with the axial curvature center C (see FIG. 4) of the nozzle inner surface R portion 107 over the entire circumferential range of the nozzle 103 without requiring any fine control. can be matched. Thereby, the normal (C9) (see FIG. 5A) of the nozzle inner surface R portion 107 and the axis C1 of the ultrasonic probe 1 can be aligned. This enables accurate measurement of the nozzle inner surface R portion 107 by the ultrasonic probe 1 .

At this time, the direction of the axis C1 (see FIG. 5A) of the probe holding mechanism 203 coincides with the direction of the normal line (C9) of the nozzle inner surface R portion 107, so the probe holding mechanism 203 also holds the probe in the direction of the axis C1. The normal direction of the ultrasonic probe 1 always coincides with the normal direction of the subject without using a gimbal or other tracing mechanism.

Therefore, due to the influence of the negative curvature (concave surface) of the nozzle inner surface 103a and the RPV inner surface 101a, the center of the ultrasonic probe 1 (the contact point on the axis C1 of the contact surface 1a1 of the wedge 1a), which is the ultrasonic wave incident point 1a0) (see FIG. 5A), even if a wedge 1a having a curvature equivalent to the curvature of the nozzle inner surface 103a where the negative curvature is maximized, a gimbal or other tracing mechanism is not used. Therefore, stable scanning can be performed without the posture of the ultrasonic probe 1 becoming unstable. In addition, when considering the error of the drawing shape and the actual shape (as-built shape) including tolerances, a gimbal mechanism in which the operating range is limited by the maximum value of the assumed angular tolerance may be used.

As described above, a complex curved surface such as the nozzle inner surface R portion 107, which is a complex three-dimensional curved surface of a small cylindrical body (nozzle 103) protruding from the side surface of a large cylindrical body (RPV) such as the nozzle 103, is detected by the ultrasonic inspection apparatus E. In the ultrasonic inspection from the inner surface side of the .

<<other embodiments>>
1. In the above-described embodiment, the nozzle (nozzle) 103 having a diameter smaller than that of the reactor pressure vessel 101, which is joined to the side surface (fuselage portion 101) of the reactor pressure vessel (RPV), is taken as an example to be inspected. However, it is not limited to this. That is, for example, it may be a nozzle joined to the side surface of a cylindrical container or pipe and having a smaller diameter than the container or pipe. Also in this case, the same effect as described above can be obtained.

2. In the above embodiment, one ultrasonic probe 1 scans along the trajectory 201, but instead, as shown in FIG. A device that is elastically held in the direction of the axis C0 at a plurality of locations may be used. Note that FIG. 7 is a schematic cross-sectional view showing a modified ultrasonic inspection apparatus E1.
In this case, since the axial scanning of the probe 1H can be omitted, an improvement in inspection speed can be expected. Since the moving mechanism 203M (see FIG. 5A) of the probe holding mechanism 203 is not required, the cost of the moving mechanism 203M is eliminated.

3. Although various configurations have been described in the above embodiments, at least some of them may be adopted. For example, the described configurations may be configured by appropriately combining configurations.

4. The configuration described in the above embodiment is an example of the present invention, and various other configurations are possible within the scope of the claims.

1 Ultrasonic Probe 1a Wedge 1H Multiple Ultrasonic Probes 101 Reactor Pressure Vessel (RPV) (large cylinder)
101a RPV inner surface (large cylinder inner surface)
102 piping (small cylinder)
102a inner surface of pipe (inner surface of small cylinder)
103 nozzle (nozzle)
103a nozzle inner surface (small cylinder inner surface)
104 outer surface R portion 107 inner surface R portion (inner surface of connection portion)
108 inspection range (surface to be inspected)
200 Rotating shaft 201 Orbit 201a Arc-shaped portion 202 Copying mechanism 202b Offset adjustment mechanism 203 Probe holding mechanism 203M Moving mechanism 230 Orbital position adjustment mechanism 231 Offset adjustment mechanism of copying mechanism 250 Probe rotation mechanism 260 Bearing mechanism (variable bearing mechanism)
261 pressing pad 262 fixed frame 280 drive unit (rotating mechanism)
300 track position adjustment mechanism (positioning means)
320 Probe rotation mechanism C Axial curvature center of nozzle inner surface R (curvature center of the inner surface of the connection part between the large cylinder and the small cylinder)
C0 Piping axis (center line of small cylinder)
C1 Axis of ultrasonic probe 1 (axis of ultrasonic probe)
C9 Normal line of nozzle inner surface R (normal line of test surface)
E, E1 Ultrasonic inspection device L ₃ Distance from the center line of the rotation axis of the orbit (distance between the orbit and the center axis of the rotation axis)
Distance to RPV inner surface from _L2 trajectory (distance to great cylinder inner surface of trajectory)

Claims (2)

a rotating shaft arranged to rotate about the center line of a small cylinder projecting from the side surface of the large cylinder;
a track including an arc-shaped portion that is slidable in the axial direction of the small cylinder with respect to the rotating shaft;
The track is attached to the inner surface of the large cylinder , the inner surface of the small cylinder, or the inner surface R of the small cylinder between the inner surface of the large cylinder and the inner surface of the small cylinder, and the track is attached to the inner surface of the small cylinder. a tracing mechanism for keeping a constant distance between the inner surface of the large cylinder , the inner surface of the small cylinder, or the inner surface of the small cylinder and the track when rotating in a direction;
a probe holding mechanism that moves along the track;
an ultrasonic probe elastically supported in the axial direction by the probe holding mechanism;
a movement mechanism for moving the track in the axial direction of the small cylinder ,
A track position adjusting mechanism is provided for adjusting the distance between the track and the central axis of the rotating shaft in the radial direction of the small cylinder.
An ultrasonic inspection device characterized by: a rotating shaft arranged to rotate about the center line of a small cylinder projecting from the side surface of the large cylinder;
a track including an arc-shaped portion that is slidable in the axial direction of the small cylinder with respect to the rotating shaft;
The track is attached to the inner surface of the large cylinder, the inner surface of the small cylinder, or the inner surface R of the small cylinder between the inner surface of the large cylinder and the inner surface of the small cylinder, and the track is attached to the inner surface of the small cylinder. a tracing mechanism for keeping a constant distance between the inner surface of the large cylinder, the inner surface of the small cylinder, or the inner surface of the small cylinder and the track when rotating in a direction;
a probe holding mechanism that moves along the track;
an ultrasonic probe elastically supported in the axial direction by the probe holding mechanism;
a moving mechanism for moving the track in the axial direction of the small cylinder;
prepared,
A variable bearing mechanism that supports the rotating shaft and can be in close contact with the inner surface of the small cylinder,
The variable bearing mechanism is
a plurality of pressing pads that are pressed against the inner surface of the small cylinder with varying pitch circle diameters;
an induction ring that rotates to one side to reduce the pitch diameter and rotates to the other side to increase the pitch diameter;
an inter-pad support arm having one side rotatably attached to the pressing pad and the other side rotatably attached to the support member, and having an elongated hole in the center through which the pin member of the guide ring slides. have
By rotating the guide ring to one side or the other side, the pressing pad is brought into close contact with the inner surface of the small cylinder by changing the diameter of the pitch circle via the inter-pad support arm. Ultrasound equipment.

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