JPH0161180B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ultrasonic inspection device for vertical tubes used in plants such as nuclear power plants. This invention relates to a probe driving device for scanning.

Examples of vertical tube bodies include a control rod drive housing (CRDH) and a neutron measurement housing (ICMH) of a pressure vessel in a boiling water nuclear reactor as shown in FIG. To explain the outline of the configuration from FIG. 1, the pressure vessel includes a pressure vessel body 1, a flange 8 provided on its upper part, a flange 7 for attaching an upper mirror 2 combined with this,
It consists of a lower mirror 3 welded to the lower part of the pressure vessel body 1, and a housing 4 and skirt 9 for driving control rods and for measuring neutrons, which are welded to the lower mirror 3. In addition, a heat insulating wall 5 is installed around the pressure vessel body.
and Gamma Shield 6. The housing 4 is shown in detail in FIG. 2. In particular, the housing for neutron measurement is shown, but the housing for driving the control rods also has a larger inner diameter, but the shape is almost the same.

Figure 2 shows an enlarged view of the housing, showing the lower mirror 3 and housing 4 of the pressure vessel.
Welded part 12 between housing 4 and flange 11
The two areas near the welded part 13 are to be inspected.
For this reason, when inspecting, it is conceivable to insert a probe into the housing 4 and conduct the ultrasonic inspection from the inner surface. However, in reality, the inner diameter of the pipe is small and the length of the housing 4 is about 4 m compared to the inner diameter.
It is extremely difficult to test for this reason.
In particular, it is very difficult to inspect the neutron measurement housing because its inner diameter is approximately 38φ.

When such a vertical tube is operated remotely and automatically inspected, the scanning direction of the probe needs to be moved in the axial direction and circumferential direction of the tube. For this reason, the mounting methods for the drive device include (1) mounting the axial and circumferential drive parts on the outside of the tube, that is, below the flange 11 in Figure 2, and (2) mounting the axial and circumferential drive parts Either one of them is inserted into the pipe near the inspection point, and the other drive part is installed outside the pipe; (3) both the axial and circumferential drive parts are installed inside the pipe body near the inspection point; There are three methods. Method (1) makes it easier to design and manufacture the drive unit because there is no space restriction, but the driving force becomes large because it moves the entire 4m, and the 4m length makes transportation and handling difficult. It is necessary to divide the probe into two parts, and there are drawbacks such as driving delays due to backlash and distortion, increased position detection errors, and decreased positioning accuracy of the probe. Method (2) is
No. 72274 (Japanese Patent Application No. 50-147422) shows a system in which an axial drive section is placed under the flange and a circumferential drive section is placed inside the pipe. The disadvantages of this are that the axial positioning accuracy decreases, similar to the previous reason, that handling becomes difficult because the drive parts are separated, and in addition, when moving in the axial direction, it must be driven against gravity. Therefore, the driving force must be increased because it is affected by the weight of the driving parts inside the pipe. Therefore, when adopting this method, the axial drive part must be placed inside the pipe.
It is advantageous to have the circumferential drive externally, since it is not influenced by weight. In the method (3), since the shaft and circumferential drive section can be arranged near the probe, backlash, undulation, etc. can be minimized, and positioning accuracy is improved. Furthermore, since the configuration of the device is simplified, it can be made smaller and lighter. However, the disadvantage of this is that the device is difficult to design and manufacture due to space limitations. In particular, since the inner diameter of the neutron measurement housing is approximately 38φ, it is extremely difficult to insert the drive unit inside the housing.

When performing ultrasonic testing, it is necessary to use a couplant such as water to improve the transmission of ultrasonic waves between the probe and the subject. Methods for supplying this couplant between the probe and the subject include (1) a method in which water is flowed between the probe and the subject, and (2) a method in which the probe and the subject are immersed in water. There is. Method (1) has the advantage of being able to reduce the amount of water because it circulates water, and that it is relatively easy to implement waterproof measures. However, if air is easily entrained in water, and if the object to be examined is thin, such as a neutron measurement housing, when the probe comes into contact with the object, the area becomes unusable for ultrasonic waves. It is necessary to keep a distance between the child and the subject.
There are drawbacks such as the inability to use this method. Method (2) is ultrasonically stable, but the water used here is treated as contaminated water, so
Increasing the amount of water will increase the amount of water to be treated, which is not desirable. Furthermore, if the drive unit is placed inside the pipe, it becomes difficult to take measures such as waterproofing.

In accordance with the American ASME standard, it is specified that the ultrasonic waves should be inspected at angles of incidence of 0°, 45°, and 60°. Therefore, it is necessary to inspect these angles, but it is not practical to attach and detach the device at each angle. Therefore, it is necessary to implement a probe with three angles, or to use a variable angle probe whose incident angle can be changed remotely. Furthermore, these ultrasonic beams need to be able to be incident both in the axial direction and in the circumferential direction. Furthermore, when these probes are attached, there is a possibility that they may not be attached at the correct angle, so it is practically effective to be able to adjust the angle to some extent.

The length from the flange 11 to the welded part 12 in Fig. 2 is approximately 4 m, and this length makes it difficult to transport and difficult to handle during installation and removal because the space for transportation to the inspection site is narrow. It can be difficult. In addition to the welded part 12, the inspection points are
There is also a weld 13 near the flange 11, and it is desirable that both of these inspection points can be inspected with one inspection device. Furthermore, since the lower mirror 3 has a curvature, the distance from the flange 11 to the welded portion 12 changes. Therefore, it is necessary to be able to follow and inspect this change. As a means of dealing with this, it is effective to lengthen the scanning stroke in the axial direction, but this has the drawback of increasing the size of the device, and a simple method is required.

An object of the present invention is to achieve higher density, stability, and precision of inspection using an apparatus for inspecting a tube from the inside using ultrasonic waves, and to save on liquid couplant.

The basic configuration of the present invention includes an axial drive means for moving an ultrasonic probe inside the tube to be inspected in the tube axis direction, and a circumferential drive means for rotating the ultrasonic probe in the circumferential direction inside the tube to be inspected. In the ultrasonic inspection apparatus, the ultrasonic inspection apparatus includes sealing means for liquid-tightly partitioning the inside of the tube to be inspected into upper and lower spaces in the middle of the tube to be inspected, and the ultrasonic probe is provided in an upper space within the tube to be inspected, the axial drive means disposed within the tube to be inspected being rotatably connected to the circumferential drive means disposed within the tube to be inspected; a supply path for the liquid contact medium in communication with the above space, and having an inlet above at least the ultrasonic probe in the upper space to discharge the liquid contact medium led out of the above space. The present invention is an ultrasonic inspection device characterized by being equipped with a channel, which enables saving of couplant and highly accurate ultrasonic inspection.

An example of the configuration of a remote automatic ultrasonic inspection device is shown in FIG. Figure 3 shows an example of the application to a small-diameter housing such as a neutron measurement housing, and shows a probe insertion mechanism 34 for inserting the probe section 21 installed inside the housing 4, and a probe insertion mechanism 34 installed at a location away from the inspection site. and transmits and receives ultrasonic signals to and from a control device 28, which is electrically connected to the probe section 21 via a cable 33, and which controls the travel of the probe section 21 and displays its position information. and a display device 29 for displaying the test results of the subject online in the form of a cross section or a plane based on the position information from the control device 28. In addition, there is a pump 30 for sending water used as a couplant, a water tank 31 for temporarily receiving the returned water, and a compressor 32 for sending air pressure to the rubber ring 26 for sealing the water. , connected to the inspection position by each pipe.

In the probe insertion mechanism 34 attached to the flange 11 of the housing 4, the distance from the welded portion 12 from the flange 11 changes due to the curvature of the lower mirror 3. This distance can be known in advance by the housing 4 attached to the lower mirror 3. Therefore, the probe insertion mechanism 34 can be positioned by operating the screw 35 in advance to slide the probe insertion mechanism 34.

The probe insertion mechanism 34 includes a plurality of connecting pipes 24 containing electric wiring and water and air piping, a probe section 21 consisting of a plurality of probes, an axial drive section 22, and a circumferential direction. a driving part 23, a rubber ring 26 for water sealing, and a connecting part 25 for connecting electrical wiring such as a connecting pipe 24, and water and air piping.
It consists of When inserting the probe insertion mechanism 34 into the housing 4, insert it without applying air pressure to the rubber ring 26, and then sequentially insert the probe insertion mechanism 34 into the connecting portion 25.
The flange 36
is fixed to the flange 11 at the lower end of the housing 4. Thereafter, by applying air pressure to the rubber ring 26, the rubber ring 26 is brought into close contact with the inner surface of the housing 4 to perform water sealing. Furthermore, water is sent to the upper part of the rubber ring 26 by the pump 30 to create a liquid level 27.
That is, an overflow surface is provided at the position of the liquid level 27. Therefore, the space between the rubber ring 26 and the liquid surface 27 can be immersed in water, and the probe section 21 moves while being immersed in water.

Axial drive section 22 and probe section 21 in FIG.
The details are shown in Figure 4. The probes include a probe 63 with a refraction angle of 0° when inspecting in the axial direction, a probe 62 with a refraction angle of 45°, and a probe 64 with a refraction angle of 60°, as well as a probe with a refraction angle when inspecting in the circumferential direction. A contact 65 with an angle of 45° and a probe 66 also with an angle of 60° are arranged on the holder 61. Although axial and circumferential inspections can be performed simultaneously, they are usually performed separately. Therefore, in the case of inspection in the circumferential direction, the number of probes is reduced and the space is secured by using the probe 63. In addition, these probes 62, 63, 64 and 65, 66 are each mounted concentrically, and the refraction angles of all of them can be adjusted concentrically with screws 67. adjusted before. It is also effective when inspecting at other refraction angles. The holder 61 rotates the shaft 57 by the axial motor 52. This rotation is female thread 6
0 to the male screw 58, but since the axial movement of the female screw 60 is restricted, the male screw 58 moves up and down as it rotates. Also, in order to restrict movement in the circumferential direction, there are two poles 56, and a male thread 58.
The bearing 58 slides together with the bearing 58. Since the holder 61 is integrated with the male screw 58 and the pawl 56, it moves in the axial direction within the housing 4. Along with this, probes 62, 63, 64, 6
5 and 66 can be scanned in the axial direction. When the vicinity of the holder 61 is viewed from the side, it is as shown in Fig. 5, and the holder 61 moves in the axial direction, like the holder 61A.
4 and 66 are all submerged in water, and the water for the couplant sent from the lower part rises in the housing 4, overflows from the pipe 79, and is led to the lower part. Therefore, a free liquid level is formed at the upper end of the pipe 9, but the liquid level can be kept at a constant position by controlling the flow rate to be fed.

If the object to be examined is thin, it cannot be inspected by contacting the inner surface of the housing 4 due to the characteristics of ultrasonic waves. For this reason, the probes 62, 63, 64, 66
must be installed at a certain distance from the inner surface of the housing 4.

The balls 51 shown in FIG. 4 are provided to prevent the case 101 from coming into contact with the inner surface of the housing 4 and to operate smoothly when inserted into the housing and when moved in the circumferential direction. This part is shown in detail in FIG. 6. That is, the balls 51, 71, and 76 are arranged along the circumference at equal intervals, and are in contact with the inner surface of the housing 4. One of the balls 71 is always pushed out along with the body 72 by a spring 73. This is because there is a manufacturing error in the inner diameter of the housing 4, so this error is accommodated so that the balls 51, 71, and 76 are always in contact with each other.

Circumferential drive part 23 and rubber ring 2 in Fig. 3
The detailed mechanism of No. 6 is shown in FIG. The probe section and the axial drive section are connected within the housing 4 by a case 101 that is integrated with the probe section and the axial drive section. The couplant water is supplied from the pipe 84 to the case 101 and the housing 4.
It ascends the inner surface, enters the probe section 21, and enters the pipe 79.
overflows at the upper end of and passes through the pipe 79,
It is taken out through the hole 89 and the pipe 91 and returned to the water tank 31 in FIG. 3. The water returned to the water tank 31 is again sent to the pipe 84 in FIG. 7 by the pump. The water used in the couplant is thus continuously circulated in a closed loop. The water seal of the housing 4 is a rubber ring 26.
inflate it by putting air pressure inside it,
This is done by contacting the inner surface of the housing 4.
Air pressure is introduced through a pipe 88 connected to the compressor. When the probe or the like is to be taken out of the housing 4, it is possible to do so by releasing a valve provided on the outside to extract air pressure from the rubber ring 26, causing it to contract, and separating it from the inner surface of the housing 4.

From FIG. 7, the cable 86 to the probe part 21 and the axial drive part thereon shows that the cable 80 of the probe part 21 is sealed by a rubber bushing 83 and another rubber bushing 81. pin 82 in space
connected by. This space is also filled with expanded fat to strengthen the water seal. The cable 80 is connected to
It is housed in a book case and rolled up in a spiral.
On the other hand, the cable to the axial drive section branches off from the rubber bush 87, passes through a pipe 79 for passing overflow water, and is routed to the upper drive section.

The circumferential drive section is fixed within the case 102, and its operating mechanism transmits the rotation of the motor 100 to the shaft 98 via gears 97 and 96. On the way, a potentiometer 99 is rotated from this shaft 98 via gears 95 and 94,
This potentiometer 99 allows rotation angle information in the circumferential direction to be sent to the control device. on the other hand,
The rotation of the shaft 98 is transmitted to the shaft 90, which is integrated with the case 101, through the gears 92 and 93, and as a result, the rotation of the shaft 98 is transmitted to the shaft 90, which is integrated with the case 101. Directional motion can be given. Furthermore, in order to avoid cutting the cable 85, the driving in the circumferential direction is limited to a range that can be inspected all around. Although the pipe 91 and the pipe 84 are cut in the middle,
This is located at a different position in the circumferential direction, or at a position separated from the motor 100, gears 95, 94, etc. by using a vinyl tube or the like.

In order to prevent the case 102 from contacting the inner surface of the housing 4, the balls 51, 71, 7 shown in FIG.
Similarly to 6, rollers 110 and 114 as shown in FIG. 8 were arranged at equal intervals in the circumferential direction at the lower part of the circumferential drive section. The rollers 110, 114 move while rotating around the shafts 111, 113, 117 only when inserted, and are in contact with the inner surface of the housing 4 after being installed. This roller 114 is also pressed against the inner surface of the housing 4 by a spring 112 in order to cope with manufacturing errors in the inner diameter of the housing 4. In this way, the balls 51 and 7 of FIG.
6, 71 and rollers 110, 116, 11 in FIG.
4 allows the distance between the inner surface of the housing and the probe to be kept constant.

A specific example of the connection portion 25 shown in FIG. 3 is shown in FIG.
Union nut 134 of case 130 and case 1
The two are connected by a screw 137 of No. 29. Along with this, water and air pipe 122 and pipe 12
1 and an electrical system socket 136 and pin 135 can be connected. In this case, an O-ring 128 for sealing water and air and an O-ring 127 for sealing water etc. from the outside are provided. In addition, the pipe 121 is connected to the bush 132.
Accordingly, the pipe 122 and the socket 136 are fixed by the bush 131. The bush 133 that fixes the pin 135 is used to lock the pipe 1 of the water system when the cases 129 and 130 are separated.
In order to prevent water from entering the pin 135 and socket 136 even if water leaks from the bush 132, the cable 125 is extended along with the bush 132. For this reason, the pipes 121 and 122 for the water and air systems and the pins 135 and sockets 136 for the electrical system are separated in two stages and separated from each other. In addition, case 13
0,129, pipe 121 and pipe 12
There are tubes 124 and 123 connected to 2, respectively. This connecting portion is shown in cross section as shown in FIG. The outer bush 132 has a pipe 141 for supplying water, a pipe 142 for guiding overflow water to the outside, and a pipe 143 for supplying air pressure. Further, a pin 136 (or socket) for electrical wiring is arranged in the inner bush 133. The pins and sockets in this example can be connected to coaxial cables for miniaturization.

The above-described embodiment has the following features, and can significantly improve inspection accuracy, operability, expansion of inspection range, and reduction of couplant.

(1) Even in a test object with a small inner diameter, such as a neutron measurement housing, the probe and the axial and circumferential drive parts can be placed close to the test location. As a result, it is possible to reduce not only the size but also the positioning accuracy and driving force.

(2) We adopted a partial immersion method in which only the scanning range of the probe is immersed in water, and to achieve this we installed a rubber ring and overflow tube that can be remotely sealed with water from the outside. As a result, a complete water seal can be achieved in the middle of the pipe, and an extremely small flow rate can be maintained at a constant level, making it possible to significantly reduce the amount of couplant material. Furthermore, since the number of contact points with the couplant is minimized, reliability in waterproofing is improved. Moreover, by making the flow of the couplant in a closed loop, the amount of the couplant can be reduced in this aspect as well, and the amount of treated water can be extremely reduced. Furthermore, since it is a water immersion method, the position of the probe can be changed depending on the thickness of the object to be examined, and since air is not involved, inspection accuracy is improved.

(3) In addition to the weld between the lower mirror and the housing, it is also possible to inspect the weld between the flange at the bottom end of the housing.
It also improves versatility.

(4) Since the probe insertion mechanism can be divided into certain lengths, attachment/detachment operations and transportation are facilitated. In addition, this division can be done by simple means for water, pneumatic systems, and electrical systems. Furthermore, since all wiring and piping are housed inside the case, troubles such as friction and catching can be prevented.

(5) Balls and rollers arranged circumferentially at regular intervals in the probe insertion mechanism allow the probe to slide smoothly inside the tube, eliminating friction in other parts. Furthermore, since one of the balls and rollers is made slidable in the thickness direction of the tube, dimensional errors in the tube during manufacturing can be absorbed.

(6) Since a rubber ring is used and it is operated by air pressure from the outside, the expansion and contraction stroke of the rubber ring can be increased, and in this respect, it is also possible to follow the dimensional error of the pipe.

(7) Probes can be placed concentrically and adjusted concentrically. Therefore, in addition to being able to adjust the refraction angle to the inspection standard, the angle can also be adjusted depending on the shape and direction of the reflector.

The present invention is not limited to nuclear power plants, but can also be applied to inspections of other vertical pipes.

In the embodiment of the present invention, multiple probes are used, but a single probe or a variable angle probe can be used depending on the inner diameter of the tube and the purpose of inspection.

In the embodiment of the present invention, a liquid layer is formed between the driving parts, but it is also possible to form a liquid layer on both driving parts, as shown in FIG. 11, for example. The probe 165 inserted into the housing 4 from FIG. etc. are guided through pipe 66 and then through pipe 16.
7 and is taken out to the outside again. The rubber ring 171 is normally contracted and is away from the four surfaces of the housing, but it can be connected to the pipe 16 from the outside.
By applying air pressure via 9, the housing 4 expands until it comes into contact with the inner surface of the housing 4, thereby forming a water seal. Axial drive is driven by motor 1
By rotating the screw 163 from 59, the nut that is integral with the probe and is engaged with this screw can be moved in the axial direction. This movement is controlled by the potentiometer 1 by gears 162 and 161.
Position information can be obtained by applying rotation to 60 and converting this resistance change into a voltage signal and outputting it to the outside. On the other hand, the drive in the circumferential direction is performed by the motor 150 via the gear 168 and gear 154 to the shaft 15.
Rotate 7. Furthermore, gear 155 and gear 15
By rotating the boss 172 via 6, the motor 159, potentiometer 160, and bosses 173, 174 connected thereto can be rotated. This allows the probe 165 and pipe 167 to also move in the circumferential direction. This liquid phase 1
All sliding parts such as the boss 174 and the lower part of the screw 163 that are in contact with the screw 70 are provided with O-rings.

As described above, according to the present invention, the axial drive means, the circumferential drive means, the ultrasonic probe, and the sealing means are all inserted and positioned at the inspection position in the pipe to be inspected, and are located above the sealing means. A liquid contact medium is supplied to the space through the supply path, and the ultrasonic probe is immersed in the liquid contact medium. The excess amount of the liquid contact medium supplied to the upper space overflows from the discharge path and is discharged outside the upper space, and the liquid surface of the liquid contact medium in the upper space always immerses the ultrasonic probe. A controlled action is performed on the level. In ultrasonic inspection, an axial drive means scans the ultrasound probe in the axial direction (up and down), and a circumferential drive means separates the axial drive means from the ultrasonic probe. Perform by scanning the tentacle in the circumferential direction. Since these axial and circumferential scans can be performed independently and individually, precise scans can be performed. When performing this scanning, the axial drive means, the circumferential drive means, and the ultrasonic probe are concentrated near the inspection position, and the axial drive means drives the ultrasonic probe. Since the load is only applied against the gravity of will be accomplished. In addition, since the circumferential drive means is located near the inspection position and all that is required is to rotate the small axial drive means, circumferential scanning can be performed smoothly and accurately without rattling. The drive means itself can be made smaller and easier to deploy inside the pipe under inspection.
This has the effect of making it easier to insert the entire ultrasonic inspection device into a narrow pipe to be inspected.

According to the present invention, which can perform such an action, each driving means is miniaturized and can be easily inserted into the inspection position in the pipe to be inspected, thereby increasing the accuracy of inspection, and scanning in the axial direction and circumferential direction can be performed independently. In addition, by controlling the liquid level of the liquid contact medium to a constant level so that there is no shortage of liquid, it is possible to save the liquid contact medium and use ultrasonic waves. At the same time, you can obtain the effect of maintaining physical stability.

[Brief explanation of drawings]

FIG. 1 is a diagram explaining the configuration near the pressure vessel of a nuclear power plant, FIG. 2 is a schematic diagram of the housing for neutron measurement and control rod drive, and FIG. 3 is the configuration of the ultrasonic inspection device of the present invention. The figure 4, which shows
FIG. 5 is a side view of the probe section, FIG. 6 is a layout diagram of the balls in contact with the subject, and FIG. FIG. 8 is a diagram showing the configuration of the roller in contact with the subject, FIG. 9 is a sectional view showing the configuration of the connecting part, and FIG. 10 is the configuration in the circumferential direction. 11 are configuration diagrams for explaining other embodiments. 3... Lower mirror, 4... Housing, 11... Flange, 12, 13... Welding section, 14... Clad, 21... Probe section, 22, 23... Drive section,
24... Connection pipe, 25... Connection part, 26... Rubber ring, 27... Liquid level, 28... Control device, 29
... Display device, 30 ... Pump, 31 ... Water tank,
32... Compressor, 33... Cable, 34
...Contact insertion mechanism, 35...screw, 36...flange.

Claims (1)

[Scope of Claims] 1. Axial drive means for moving the ultrasonic probe inside the tube to be inspected in the tube axis direction, and circumferential drive for rotating the ultrasonic probe in the circumferential direction inside the tube to be inspected. In the ultrasonic inspection apparatus, the ultrasonic inspection apparatus includes sealing means for liquid-tightly partitioning the interior of the tube to be inspected into an upper and lower space in the middle of the tube to be inspected, and the ultrasonic probe is separated from the sealing device. provided in an upper space within the tube to be inspected, the axial drive means disposed within the tube to be inspected being rotatably connected to the circumferential drive means disposed within the tube to be inspected; a supply path for the liquid contact medium in communication with the above space, and having an inlet above at least the ultrasonic probe in the upper space to discharge the liquid contact medium led out of the above space. An ultrasonic inspection device characterized by being equipped with a channel. 2. In claim 1, the axial drive means includes a motor and a motion conversion means that converts the rotational motion of the motor into linear motion of the ultrasonic probe, and the motor An ultrasonic inspection device characterized in that the ultrasonic probe is installed above the entrance of the discharge path, and the ultrasonic probe is installed below the entrance of the discharge path. 3. The ultrasonic inspection apparatus according to claim 1, wherein each motor of both of the driving means is installed in a space below the sealing means.