JP2021076500A - Ultrasonic flaw detector and inspection method for jet pump beam - Google Patents

Abstract

To enable ultrasonic flaw detection on an inspection object to be carried out with high accuracy in a reduced execution period.SOLUTION: The present invention is constituted by comprising: an ultrasonic probe 21 for propagating an ultrasonic wave to a jet pump beam 3 via cooling water W as a medium, without touching a top face 14 of the jet pump beam 3; a scanning mechanism (top face first scanning mechanism 25, top face second scanning mechanism 26) installed to a device frame 22, for moving the ultrasonic probe 21 in a second direction orthogonal to the top face 14 of the jet pump beam 3 and causing it to scan; and a fixing mechanism 23 for fixing and attaching the device frame 22 to the jet pump beam 3.SELECTED DRAWING: Figure 5

Description

An embodiment of the present invention relates to an ultrasonic flaw detector that propagates ultrasonic waves to an object to be inspected to detect ultrasonic flaws, and a method for inspecting a jet pump beam that detects and inspects a jet pump beam as an object to be inspected by ultrasonic flaws. ..

Welded parts of structures in nuclear facilities are places where defects such as cracks may occur because various stresses such as residual stress are concentrated. Ultrasonic flaw detection has been conventionally known as a technique for detecting defects generated in such welds. This ultrasonic flaw detection is a technology that transmits an ultrasonic beam to an inspection object from an ultrasonic sensor called a probe and analyzes the reflected wave to determine whether or not there is a defect in the inspection object. is there.

By the way, some structures in a nuclear reactor are used under severe stress conditions. For example, among the plurality of jet pump components arranged in the annular region between the reactor pressure vessel and the core shroud, there is a member called a jet pump beam that holds the inlet mixer in a restrained manner. This jet pump beam is affected by the pressure of the coolant in the reactor pressure vessel and the fluid vibration caused by the coolant flowing in the inlet mixer, and the conditions are severe in terms of stress.

Such parts are designed and manufactured to withstand the full life of the reactor, but in the unlikely event that a minute crack occurs during operation, the occurrence of a crack is discovered early. It is desirable to do. Therefore, a technique for ultrasonically detecting a jet pump beam by using an ultrasonic flaw detector equipped with an ultrasonic probe is disclosed.

Japanese Unexamined Patent Publication No. 57-53657

By the way, the conventional ultrasonic flaw detector cannot detect flaws unless an ultrasonic probe is pressed against a predetermined location such as a welded portion or a base material of a furnace structure to be inspected to bring them into close contact with each other. It was necessary to have a combined pressing mechanism, and it was possible to detect only the scannable surface by a flat flaw detection operation such as a horizontal plane or a vertical plane. Further, when the flaw detection surface is small, there is a problem that a space for pressing the ultrasonic probe cannot be secured.

Furthermore, since the ultrasonic flaw detector of the jet pump beam needs to be provided with a dedicated ultrasonic probe for each of the non-continuous flaw detection surfaces, there is a risk of failure of the ultrasonic probe and the device. There were problems such as an increase in the number of parts. Further, an ultrasonic flaw detector for the purpose of inspecting a jet pump beam can transmit ultrasonic waves only from a plane on which an ultrasonic probe can be pressed by using a pressing mechanism. For this reason, ultrasonic waves cannot be incident on the vicinity of the fitting portion of the jet pump beam with the transition piece, and the entire volume of the jet pump beam cannot be detected.

An embodiment of the present invention has been made in consideration of the above circumstances, and an object of the present invention is to provide an ultrasonic flaw detector capable of performing ultrasonic flaw detection on an inspection object with high accuracy and shortening the construction period. And. Another object of the present invention is to provide a method for inspecting a jet pump beam, which can perform ultrasonic flaw detection on the jet pump beam with high accuracy and shorten the construction period.

The ultrasonic flaw detector according to the embodiment of the present invention is installed on the device frame and an ultrasonic probe that propagates ultrasonic waves to the inspection target through a liquid without contacting the flaw detection surface of the inspection target. It has a scanning mechanism for moving the ultrasonic probe in two directions orthogonal to the flaw detection surface to scan, and a fixing mechanism for fixing and attaching the device frame to the inspection object. It is characterized by being done.

The method for inspecting a jet pump beam according to an embodiment of the present invention is a method for inspecting a jet pump beam that ultrasonically detects a jet pump beam, which is a component of a jet pump installed in a reactor pressure vessel, and is said to be ultrasonic. It is characterized in that the entire volume of the jet pump beam is ultrasonically detected by using a flaw detector while the jet pump beam is installed in the reactor pressure vessel.

According to the embodiment of the present invention, ultrasonic flaw detection on an object to be inspected can be performed with high accuracy and shortened construction period.

A side view showing a situation in which the beam top surface ultrasonic flaw detector, which is the first embodiment of the ultrasonic flaw detector according to the embodiment, is attached to the jet pump beam. FIG. 1 is a view on arrow II of FIG. The front view which shows the whole structure of the jet pump of FIG. 1 and FIG. FIG. 3 is a cross-sectional view taken along the line IV-IV of FIG. The side view which shows the structure of the beam top surface ultrasonic flaw detector of FIG. 1 and FIG. FIG. 5 is a view taken along the line VI. A vertical cross-sectional view showing the configuration of the fixing mechanism of FIGS. 5 and 6. (A) is a partially developed view of the outer peripheral surface of the pole connecting portion in FIGS. 5 and 6, and (B) is a partially developed view of the inner peripheral surface of the detachable portion in FIGS. 1 and 2. The state of flaw detection of the ultrasonic probe of FIGS. 5 and 6 with respect to the jet pump beam is shown, (A) is a plan view, and (B) is a side view. The front view which shows the structure of the beam side surface ultrasonic flaw detection apparatus which is the 2nd form of the ultrasonic flaw detection apparatus which concerns on one Embodiment. XI arrow view of FIG. 10. 10 and 11 show the ultrasonic probe and the jet pump beam, (A) is a plan view showing the adjustment status of the parallelism of the ultrasonic probe, and (B) is the jet of the ultrasonic probe. A side view showing the state of flaw detection for the pump beam.

Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.
FIG. 1 is a side view showing a situation in which the beam upper surface ultrasonic flaw detector, which is the first embodiment of the ultrasonic flaw detector according to the embodiment, is attached to the jet pump beam, and FIG. 2 is a view taken along the line II of FIG. Is. Further, FIG. 5 is a side view showing the configuration of the beam upper surface ultrasonic flaw detector of FIGS. 1 and 2, and FIG. 10 is a beam side ultrasonic flaw detector which is a second embodiment of the ultrasonic flaw detector according to the embodiment. It is a front view which shows the structure of the flaw detector. The beam upper surface ultrasonic flaw detector 20 which is the first form of the ultrasonic flaw detector and the beam side surface ultrasonic flaw detector 50 which is the second form are both parts of the jet pump 2 installed in the reactor pressure vessel 1. The jet pump beam 3 is subjected to ultrasonic flaw detection to inspect the presence or absence of defects existing in the jet pump beam 3.

Here, as shown in FIG. 1, a plurality of jet pumps 2 are installed in the reactor pressure vessel 1 in the annular region between the reactor pressure vessel 1 and the core shroud 11, and the cooling material (cooling water W) is installed. ) Is guided below the core (not shown) surrounded by the core shroud 11. In the jet pump 2, as shown in FIGS. 3 and 4, the coolant supply pipe 5 is arranged between the pair of jet pump main bodies 4, the one coolant supply pipe 5, and the pair of jet pump main bodies 4. In this state, the jet pump main body 4 and the inlet mixer 6 connected to the upper part of the coolant supply pipe 5 are provided. Transition pieces 7 are attached to the front side and the back side of the inlet mixer 6, respectively.

Both tip portions 3A of the jet pump beam 3 are fitted into the fitting recesses 8 of the transition pieces 7 attached to the front side and the back side of the inlet mixer 6, respectively. A beam bolt 10 is screwed into the jet pump beam 3 in a threaded state through a screw hole 9 (see FIG. 9) formed at a central position in the longitudinal direction A of the jet pump beam 3. The jet pump beam 3 is installed as a part of the jet pump 2 with the beam bolt 10 in contact with the inlet mixer 6. Since a predetermined initial load is applied to the jet pump beam 3, the restoring force of the jet pump beam 3 acts on the inlet mixer 6 via the beam bolt 10 to supply the coolant to the inlet mixer 6. The pressure of the material and the reaction force of the coolant injected from the inlet mixer 6 are suppressed.

Reference numeral 12 in FIG. 4 is a keeper 12 of the beam bolt 10, and a plate 13 is interposed between the keeper 12 and the jet pump beam 3. Further, as shown in FIGS. 4 and 9, the jet pump beam 3 is provided with upper surfaces 14 on both sides of the screw holes 9 and the beam bolts 10, and the upper surfaces 14 are the tip 3A of the jet pump beam 3. It is formed so as to taper toward. Further, both side surfaces 15 of the jet pump beam 3 are also formed so as to be tapered toward the tip portion 3A. Further, on both side surfaces 15 of the jet pump beam 3, a trunnion 16 is projected from the center position of the jet pump beam 3 in the longitudinal direction A in the lateral direction B of the jet pump beam 3.

By the way, as shown in FIGS. 1 and 2, this jet pump is in a state where the reactor pressure vessel 1 is filled with a cooling material (cooling water W) and the jet pump 2 is installed in the reactor pressure vessel 1. In order to perform ultrasonic flaw detection on the jet pump beam 3 of 2, a plurality of operating poles 17 are connected above the reactor pressure vessel 1. Then, the attachment / detachment portion 19 of the attachment / detachment mechanism 18 (described in detail later) is attached to the lowermost end of the connected operation pole 17, and the beam upper surface ultrasonic flaw detector 20 attached to the operation pole 17 is used by using the attachment / detachment mechanism 18. (FIGS. 5 and 6) and the beam side ultrasonic flaw detector 50 (FIGS. 10 and 11) are positioned at the required water depth.

By allowing these beam upper surface ultrasonic flaw detectors 20 and beam side surface ultrasonic flaw detectors 50 to access the jet pump beam 3 in the installed state, the beam upper surface ultrasonic flaw detector 20 causes the upper surface 14 of the jet pump beam 3 to be viewed on the beam side surface. The side surface 15 of the jet pump beam 3 is ultrasonically detected by the ultrasonic flaw detector 50. The beam upper surface ultrasonic flaw detector 20 and the beam side surface ultrasonic flaw detector 50 will be described below.

As shown in FIGS. 5 and 6, the beam upper surface ultrasonic flaw detector 20 is installed in a state where the reactor pressure vessel 1 is filled with a cooling material (cooling water W) as described above. Ultrasonic flaw detection is performed by irradiating the upper surface 14 as the flaw detection surface of the above surface with ultrasonic waves, and the ultrasonic probe 21, the device frame 22, the fixing mechanism 23, the positioning means 24, the upper surface first scanning mechanism 25, It is configured to include a top surface second scanning mechanism 26, a pole connecting portion 27, and a contact sensor 36 (FIG. 7) as a detecting means.

The ultrasonic probe 21 is non-contact with the upper surface 14 of the jet pump beam 3 as an inspection object, and irradiates (transmits) ultrasonic U to the jet pump beam 3 using the cooling water W as a liquid as a medium. It is a water-immersed ultrasonic probe that propagates, receives reflected waves, and ultrasonically detects the jet pump beam 3. In the ultrasonic probe 21, a large number of elements that transmit and receive ultrasonic waves U are linearly arranged on the transmission / reception surface 21M, and the transmission / reception surface 21M is positioned parallel to the upper surface 14 of the jet pump beam 3.

The device frame 22 mainly accommodates the upper surface first scanning mechanism 25, and the pole connecting portion 27 is fixed to the top surface of the device frame 22. The pole connecting portion 27 constitutes the attachment / detachment mechanism 18 together with the attachment / detachment portion 19 attached to the lowermost position of a plurality of connected operation poles 17 (FIGS. 1 and 2).

As shown in FIGS. 5 and 8, a hook-shaped fitting groove 28 is formed on the outer peripheral surface 27A of the pole connecting portion 27, and a protrusion 29 is projected on the inner peripheral surface 19A of the detachable portion 19. .. By fitting the protrusion 29 of the attachment / detachment portion 19 of the operation pole 17 into the fitting groove 28 of the pole connection portion 27 of the beam upper surface ultrasonic flaw detector 20, the pole connection portion 27 is detachably connected to the attachment / detachment portion 19. , The beam upper surface ultrasonic flaw detector 20 is attached to the operation pole 17. In this state, the worker 32 on the work trolley 31 provided on the operation floor 30 (FIG. 1) of the reactor containment vessel uses the operation pole 17 to perform the beam upper surface ultrasonic flaw detector 20 on the jet pump beam 3. Is suspended to the specified water depth where.

As shown in FIGS. 5, 6 and 7, the tubular body portion 33 of the fixing mechanism 23 is fixed to the bottom surface of the device frame 22. The beam bolt 10 and the keeper 12 of the jet pump beam 3 are inserted into the tubular body portion 33 when the beam upper surface ultrasonic flaw detector 20 is attached to the jet pump beam 3. An air cylinder 34 as a gripping means is installed on the side surface of the tubular body portion 33, and the fixing mechanism 23 is formed by the tubular body portion 33 and the air cylinder 34.

The air cylinder 34 presses the keeper 12 with the piston rod 35 in a state where the beam bolt 10 and the keeper 12 of the jet pump beam 3 are inserted into the cylinder body 33, and the piston rod 35 and the cylinder body 33 press the keeper 12. By grasping the keeper 12, the beam upper surface ultrasonic flaw detector 20 is fixedly attached to the jet pump beam 3.

As shown in FIGS. 5 and 6, the positioning means 24 is fixed to the side surface of the tubular body portion 33 of the fixing mechanism 23. The positioning means 24 has an L-shape when viewed from the side, and the tip portion 24A is formed in a U-shape. Positioning when the beam upper surface ultrasonic flaw detector 20 mounted on the operation pole 17 by the attachment / detachment mechanism 18 and suspended to the installation position of the jet pump beam 3 is fixedly attached to the jet pump beam 3 by the fixing mechanism 23. The tip 24A of the means 24 is fitted into the tranion 16 of the jet pump beam 3 in the installed state, and the posture of the beam upper surface ultrasonic flaw detector 20 is positioned with reference to the tranion 16. The beam upper surface ultrasonic flaw detector 20 is fixedly attached to the jet pump beam 3 in the installed state by the fixing mechanism 23 in a state where the posture is positioned by the positioning means 24.

As shown in FIG. 7, the contact sensor 36 is provided on the bottom surface portion of the tubular body portion 33 of the fixing mechanism 23. In the contact sensor 36, the beam upper surface ultrasonic flaw detector 20 mounted on the operation pole 17 is suspended via the attachment / detachment mechanism 18, and the tubular body 33 of the fixing mechanism 23 of the beam upper surface ultrasonic flaw detector 20 is jetted. When it comes into contact with the plate 13 of the pump beam 3, the contact (seating) between the tubular body portion 33 and the plate 13 is detected. After the detection signal is output from the contact sensor 36, the air cylinder 34 of the fixing mechanism 23 operates to fix the beam upper surface ultrasonic flaw detector 20 to the jet pump beam 3. The contact sensor 36 may be attached to, for example, the device frame 22 to detect that the device frame 22 has come into contact with the installed jet pump beam 3.

As shown in FIGS. 5 and 6, the upper surface first scanning mechanism 25 and the upper surface second scanning mechanism 26 have two directions in which the ultrasonic probe 21 is orthogonal to the upper surface 14 (scratch detection surface) of the jet pump beam 3. The upper surface second scanning mechanism 26 is installed in the upper surface first scanning mechanism 25. The upper surface first operation mechanism 25 is housed in the device frame 22 and installed in the device frame 22.

That is, in the upper surface first scanning mechanism 25, the upper surface first scanning motor 37 is installed on the device frame 22, and the screw shaft 38 is rotatably installed on the device frame 22, and the nut is screwed onto the screw shaft 38. It has a slider 39 with (not shown). The rotational force of the upper surface first scanning motor 37 is transmitted to the screw shaft 38 via the pulley 40 and the belt 41, and moves the slider 39 along the guide rod 39A in the lateral direction B of the jet pump beam 3.

In the upper surface second scanning mechanism 26, the upper surface second scanning motor 43 is installed on the probe frame 42 fixed to the slider 39 of the upper surface first scanning mechanism 25, and the screw shaft 44 is attached to the probe frame 42. It has a slider 45 that is rotatably installed and has a nut (not shown) that is screwed onto the screw shaft 44. An ultrasonic probe 21 is installed on the slider 45. The rotational force of the upper surface second scanning motor 43 is transmitted to the screw shaft 44 via the pulley 46 and the belt 47, and the slider 45 is moved along the guide rod or guide rail (both not shown) on the upper surface 14 of the jet pump beam 3. It is moved in the inclined surface direction C, and the ultrasonic probe 21 is moved in the same direction (inclined surface direction C).

Next, the ultrasonic flaw detection operation on the upper surface 14 of the jet pump beam 3 by the beam upper surface ultrasonic flaw detector 20 will be described.
As shown in FIGS. 5, 6 and 9, first, the upper surface second scanning motor 43 is driven to position the ultrasonic probe 21 at a predetermined position in the inclined surface direction C on the upper surface 14 of the jet pump beam 3. Position it. After that, the first scanning motor 37 on the upper surface is driven to move the ultrasonic probe 21 in the lateral direction B on the upper surface 14 of the jet pump beam 3, and the ultrasonic probe 21 causes the jet pump beam 3 to move. The top surface 14 is scanned. Next, the upper surface second scanning motor 43 is driven to feed the ultrasonic probe 21 by a predetermined amount pitch in the inclined surface direction C on the upper surface 14 of the jet pump beam 3, and then the upper surface first scanning motor 37 is moved. Reverse drive. By this reversal drive, the ultrasonic probe 21 is moved in the opposite direction to the lateral direction B on the upper surface 14 of the jet pump beam 3, and the ultrasonic probe 21 scans the upper surface 14 of the jet pump beam 3. By repeating the above operation, the ultrasonic probe 21 scans the entire surface of the upper surface 14 of the jet pump beam 3.

In contrast to the scanning of the upper surface 14 of the jet pump beam 3 as described above, the following scanning is also assumed. First, the first scanning motor 37 on the upper surface is driven to position the ultrasonic probe 21 at a predetermined position on the upper surface 14 of the jet pump beam 3 in the lateral direction B. After that, the upper surface second scanning motor 43 is driven to move the ultrasonic probe 21 in the inclined surface direction C on the upper surface 14 of the jet pump beam 3, and the ultrasonic probe 21 causes the jet pump beam 3 to move. The top surface 14 is scanned. Next, the upper surface first scanning motor 37 is driven to feed the ultrasonic probe 21 in the lateral direction B on the upper surface 14 of the jet pump beam 3 by a predetermined amount, and then the upper surface second scanning motor 43 is moved. Reverse drive. By this reversal drive, the ultrasonic probe 21 is moved in the direction opposite to the inclined surface direction C on the upper surface 14 of the jet pump beam 3, and the ultrasonic probe 21 scans the upper surface 14 of the jet pump beam 3. By repeating the above operation, the ultrasonic probe 21 may scan the entire surface of the upper surface 14 of the jet pump beam 3.

For ultrasonic flaw detection on the screw hole 9 of the jet pump beam 3 and the other upper surface 14 symmetrical with respect to the beam bolt 10, the beam upper surface ultrasonic flaw detector 20 is 180 centered on the beam bolt 10 of the jet pump beam 3. This is performed by rotating the beam by 180 degrees and changing the posture of the ultrasonic flaw detector 20 on the upper surface of the beam by 180 degrees. This 180-degree attitude change operation is performed by directly rotating the operation pole 17 by the worker 32 after releasing the grip by the air cylinder 34, or by providing the pole connecting portion 27 of the beam upper surface ultrasonic flaw detector 20. It is done by rotating a rotating mechanism that does not.

As shown in FIGS. 10 and 11, the beam side ultrasonic flaw detector 50 has a flaw detection surface of the jet pump beam 3 installed in a state where the reactor pressure vessel 1 is filled with a cooling material (cooling water W). Ultrasonic flaw detection is performed by irradiating the side surface 15 with ultrasonic waves, and the ultrasonic probe 51, the device frame 52, the fixing mechanism 23, the positioning means 24, the pole connecting portion 27, and the contact sensor 36. The side surface first scanning mechanism 53, the side surface second scanning mechanism 54, the extension mechanism 55, and the angle changing mechanism 57 are included. The same parts as the beam upper surface ultrasonic flaw detector 20 in the beam side surface ultrasonic flaw detector 50 are designated by the same reference numerals as those of the beam upper surface ultrasonic flaw detector 20 to simplify or omit the description.

The ultrasonic probe 51 is non-contact with the side surface 15 of the jet pump beam 3 as an inspection target as a flaw detection surface, and irradiates the jet pump beam 3 with ultrasonic waves U using the cooling water W as a liquid as a medium. It is a water-immersed ultrasonic probe that transmits (transmits) and propagates, receives reflected waves, and ultrasonically detects the jet pump beam 3. In the ultrasonic probe 51, a large number of elements for transmitting and receiving ultrasonic waves U are linearly arranged on the transmitting and receiving surface 51M.

The pole connecting portion 27 is fixed to the top surface of the device frame 52, and the tubular body portion 33 of the fixing mechanism 23 is fixed to the bottom surface. An air cylinder 34 and a positioning means 24 are installed on the tubular body 33, respectively, and a contact sensor 36 (FIG. 7) is provided on the bottom surface of the tubular body 33.

The beam side ultrasonic flaw detector 50, which is attached to the operation pole 17 by the attachment / detachment mechanism 18 and suspended to the installation position of the jet pump beam 3, is formed by fitting the positioning means 24 into the trunnion 16 of the jet pump beam 3. The posture is positioned. Then, in the beam side ultrasonic flaw detector 50, the beam bolt 10 and the keeper 12 of the jet pump beam 3 are inserted into the cylinder portion 33 of the fixing mechanism 23, and the contact sensor 36 comes into contact with the plate 13 of the jet pump beam 3. As a result, the air cylinder 34 of the fixing mechanism 23 operates, and the fixing mechanism 23 fixes and attaches to the jet pump beam 3.

The side surface first scanning mechanism 53 and the side surface second scanning mechanism 54 move the ultrasonic probe 51 in two directions orthogonal to the side surface 15 (scratch detection surface) of the jet pump beam 3 to scan. The side surface second scanning mechanism 54 is housed in the device frame 52 and installed in the device frame 52. The side surface first scanning mechanism 53 is housed in the apparatus frame 52 and installed in the extension mechanism 55 installed in the side surface second scanning mechanism 54. An angle changing mechanism 57 is installed in the side surface first scanning mechanism 53, and an ultrasonic probe 51 is installed in the angle changing mechanism 57.

In the side surface second scanning mechanism 54, the side surface second scanning motor 58 is installed on the device frame 52, and the screw shaft 59 is rotatably installed on the device frame 52, and a nut screwed onto the screw shaft 59 (not). It has a slide 60 with (shown). A plate-shaped second scanning frame 64 is fixed to the slide 60. The rotational force of the side surface second scanning motor 58 is transmitted to the screw shaft 59 via the pulley 61 and the belt 62, and moves the slide 60 along the guardrail 63 in the longitudinal direction A of the jet pump beam 3. As a result, the ultrasonic probe 51 is moved in the longitudinal direction A of the jet pump beam 3.

In the extension mechanism 55, an extension motor 65 is installed on the second scanning frame 64, and a screw shaft 66 is rotatably installed on the second scanning frame 64, and a nut screwed onto the screw shaft 66 (not shown). Has a slide 67 with. An extension frame 68 having a substantially T-shaped side view is fixed to the slide 67. The rotational force of the extension motor 65 is transmitted to the screw shaft 66 via the pulley 69 and the belt 70, and moves the slider 67 and the extension frame 68 along the guardrail 70A in the lateral direction B of the jet pump beam 3. The movement of the extension frame 68 adjusts the distance between the ultrasonic probe 51 and the side surface 15 of the jet pump beam 3.

The side surface first scanning mechanism 53 has a side surface first scanning motor 71 installed on the extension frame 68, and a slidable slider 73 on a guide rod 72 provided in the extension frame 68 in the vertical direction. A first scanning frame 74 having a substantially L-shape in rear view is fixed to the slider 73. The rotational force of the side surface first scanning motor 71 is transmitted to the slider 73 via a pinion 75 provided on the motor shaft of the side surface first scanning motor 71 and a rack 76 provided on the slider 73, and the slider 73 is transmitted. And the first scanning frame 74 is moved in the vertical direction D along the guide rod 72. As a result, the ultrasonic probe 51 is moved in the vertical direction D of the jet pump beam 3.

In the angle changing mechanism 57, the angle changing motor 77 is installed in the vertical direction D on the first scanning frame 74, and the rotating rod 78 is installed in the vertical direction D on the first scanning frame 74, and the tip of the rotating rod 78 is installed. The ultrasonic probe 51 is fixedly attached to the device. The rotational force of the angle changing motor 77 is transmitted to the rotary rod 78 via the belt 79 and the pulley 80, and by rotating the rotary rod 78 around its axis, as shown in FIG. 12 (A), the jet pump The angle of the ultrasonic probe 51 with respect to the side surface 15 of the beam 3 is changed. Since the side surface 15 of the jet pump beam 3 is formed so as to be tapered toward the tip portion 3A, the ultrasonic probe with respect to the side surface 15 can be detected by changing the angle of the ultrasonic probe 51 with respect to the side surface 15. The parallelism of the tentacle 51 is adjusted.

Next, the ultrasonic flaw detection operation with respect to the side surface 15 of the jet pump beam 3 by the beam side surface ultrasonic flaw detector 50 described above will be described.
As shown in FIGS. 10, 11 and 12, first, the side surface second scanning motor 58 is driven to position the ultrasonic probe 51 at a predetermined position in the longitudinal direction A on the side surface 15 of the jet pump beam 3. .. After that, the extension motor 65 is driven to adjust the distance between the side surface 15 of the jet pump beam 3 and the ultrasonic probe 51, and the angle changing motor 77 is further driven with respect to the side surface 15 of the jet pump beam 3. Adjust the parallelism of the ultrasonic probe 51. Next, the side surface first scanning motor 71 is driven to move the ultrasonic probe 51 in the vertical direction D on the side surface 15 of the jet pump beam 3, and the ultrasonic probe 51 causes the jet pump beam 3 to move. The side surface 15 is scanned in the vertical direction D.

Next, the side surface second scanning motor 58 is driven to feed the ultrasonic probe 51 by a predetermined amount in the longitudinal direction A on the side surface 15 of the jet pump beam 3. After that, the extension motor 65 is driven to adjust the distance between the side surface 15 of the jet pump beam 3 and the ultrasonic probe 51, and the angle changing motor 77 is further driven to drive the side surface of the jet pump beam 3. The parallelism of the ultrasonic probe 51 with respect to 15 is adjusted, and then the side surface first scanning motor 71 is reversely driven. By this reversal drive, the ultrasonic probe 51 is moved in the direction opposite to the vertical direction D on the side surface 15 of the jet pump beam 3, and the side surface 15 of the jet pump beam 3 is moved in the vertical direction D by the ultrasonic probe 51. To scan. By repeating the above operation, the entire surface of the side surface 15 of the jet pump beam 3 is scanned by the ultrasonic probe.

In contrast to the above-mentioned scan on the side surface 15 of the jet pump beam 3, the following scan is also assumed. First, the side surface first scanning motor 71 is driven to position the ultrasonic probe 51 at a predetermined position in the vertical direction D on the side surface 15 of the jet pump beam 3. Next, the extension motor 65 is driven to adjust the distance between the side surface 15 of the jet pump beam 3 and the ultrasonic probe 51, and the angle changing motor 77 is driven with respect to the side surface 15 of the jet pump beam 3. While adjusting the parallelism of the ultrasonic probe 51, the side surface second scanning motor 58 is driven. The ultrasonic probe 51 is moved in the longitudinal direction A on the side surface 15 of the jet pump beam 3 by driving the side surface second scanning motor 58, and the side surface 15 of the jet pump beam 3 is moved by the ultrasonic probe 51. Is scanned in the longitudinal direction A of the jet pump beam 3.

Next, the side surface first scanning motor 71 is driven to feed the ultrasonic probe 51 by a predetermined amount in the vertical direction D on the side surface 15 of the jet pump beam 3. After that, the extension motor 65 is driven to adjust the distance between the ultrasonic probe 51 and the side surface 15 of the jet pump beam 3, and the angle changing motor 77 is driven to superimpose the jet pump beam 3 with respect to the side surface 15. While adjusting the parallelism of the ultrasonic probe 51, the side surface second scanning motor 58 is reversely driven. By this reversal drive, the ultrasonic probe 51 is moved in the direction opposite to the longitudinal direction A on the side surface 15 of the jet pump beam 3, and the side surface 15 of the jet pump beam 3 is moved by the ultrasonic probe 51 to the jet pump beam. Scan in the longitudinal direction A of 3. By repeating the above operation, the entire surface of the side surface 15 of the jet pump beam 3 may be scanned by the ultrasonic probe 51.

For ultrasonic flaw detection on the other side surface 15 located on the opposite side of the jet pump beam 3, the beam side ultrasonic flaw detector 50 is used for the beam bolt 10 of the jet pump beam 3 as in the case of the beam top surface ultrasonic flaw detector 20. It is carried out by rotating 180 degrees around the beam and changing the posture of the beam side ultrasonic flaw detector 50 by 180.

Next, an inspection method of the jet pump beam 3 using the beam upper surface ultrasonic flaw detector 20 and the beam side surface ultrasonic flaw detector 50 configured as described above, that is, an ultrasonic flaw detection method of the jet pump beam 3 will be described.

When the jet pump beam 3 is ultrasonically detected with the jet pump 2 including the jet pump beam 3 installed in the reactor pressure vessel 1 filled with the cooling material (cooling water W), FIGS. 1 and 2 show. As shown, the worker 32 rides on the work trolley 31 installed on the operation floor 30 of the reactor containment vessel, connects a plurality of operation poles 17, and attaches / detaches the attachment / detachment mechanism 18 provided at the lowermost end thereof. The pole connecting portion 27 of the beam upper surface ultrasonic flaw detector 20 or the beam side surface ultrasonic flaw detector 50 is detachably attached to the portion 19.

In this state, the worker 32 operates the operation pole 17 to suspend the beam upper surface ultrasonic flaw detector 20 or the beam side surface ultrasonic flaw detector 50 to the position of the jet pump beam 3. For example, when the beam upper surface ultrasonic flaw detector 20 is attached to the operation pole 17 via the attachment / detachment mechanism 18, the beam upper surface ultrasonic flaw detector 20 is used to cover the entire surfaces of the two upper surfaces 14 of the jet pump beam 3. Ultrasonic flaw detection. When the beam side surface ultrasonic flaw detector 50 is attached to the operation pole 17 via the attachment / detachment mechanism 18, the beam side surface ultrasonic flaw detector 50 covers the entire surfaces of both side surfaces 15 of the jet pump beam 3 by the beam side surface ultrasonic flaw detector 50. Ultrasonic flaw detection.

The worker 32 remotely connects and disconnects the beam upper surface ultrasonic flaw detector 20 and the operation pole 17, and connects and disconnects the beam side ultrasonic flaw detector 50 and the operation pole 17, respectively, using the attachment / detachment mechanism 18. By doing so, the ultrasonic flaw detection of the upper surface 14 of the jet pump beam 3 by the beam upper surface ultrasonic flaw detector 20, the ultrasonic flaw detection of the side surface 15 of the jet pump beam 3 by the beam side surface ultrasonic flaw detector 50, and the attachment / detachment mechanism 18 are performed. The operation pole 17 used and the ultrasonic flaw detectors 20 and 50 are attached and detached in parallel, respectively, to ultrasonically flaw the entire volume of the jet pump beam 3.

Since it is configured as described above, according to the present embodiment, the following effects (1) to (4) are achieved.
(1) As shown in FIGS. 5, 6, 10 and 11, the ultrasonic probes 21 and 51 of the beam top surface ultrasonic flaw detector 20 and the beam side surface ultrasonic flaw detector 50 are jet pumps, respectively. It is a water-immersed ultrasonic probe that propagates ultrasonic waves U to the jet pump beam 3 using a cooling material (cooling water W) as a medium without contacting the flaw detection surface (upper surface 14. side surface 15) of the beam 3. Therefore, high-precision and high-quality ultrasonic flaw detection can be realized for the jet pump beam 3 without being affected by the shape change of the flaw detection surface (upper surface 14 and side surface 15). Therefore, since the entire volume of the jet pump beam 3 can be ultrasonically detected while it is installed in the reactor pressure vessel 1, the flaw detection construction period can be shortened.

(2) Since the entire area of the jet pump beam 3 is ultrasonically detected by the beam upper surface ultrasonic flaw detector 20 and the beam side surface ultrasonic flaw detector 50, when a minute defect (crack) occurs in the jet pump beam 3. Can also detect this defect early. As a result, the reliability of inspection and maintenance of the jet pump beam 3 can be improved.

(3) Since the beam upper surface ultrasonic flaw detector 20 or the beam side surface ultrasonic flaw detector 50 can be attached to and detached from the lower end of the operation pole 17 by remote operation using the attachment / detachment mechanism 18, the jet pump by the beam upper surface ultrasonic flaw detector 20 Ultrasonic flaw detection work on the upper surface 14 of the beam 3, ultrasonic flaw detection work on the side surface 15 of the jet pump beam 3 by the beam side surface ultrasonic flaw detector 50, operation poles 17 by the attachment / detachment mechanism 18, and ultrasonic flaw detectors 20 and 50. Can be carried out in parallel with the work of attaching and detaching. Therefore, the construction period for ultrasonically detecting the jet pump beam 3 in the installed state can be shortened by using the beam upper surface ultrasonic flaw detector 20 and the beam side surface ultrasonic flaw detector 50.

(4) By suspending the beam upper surface ultrasonic flaw detector 20 or the beam side surface ultrasonic flaw detector 50 in the reactor pressure vessel 1 by using the operation pole 17 without using the overhead crane in the reactor storage vessel. With the jet pump 2 installed in the reactor pressure vessel 1, ultrasonic flaw detection can be performed on the jet pump beam 3 of the jet pump 2. Therefore, ultrasonic flaw detection of the jet pump beam 3 can be performed in parallel with the inspection work of the internal structure in which the periodic inspection is carried out in the installed state and the work using a lifting machine such as an overhead crane. As a result, the inspection work period in the reactor pressure vessel 1 can be shortened.

Although the embodiment of the present invention has been described above, this embodiment is presented as an example and is not intended to limit the scope of the invention. This embodiment can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the gist of the invention, and the replacements and changes thereof can be made. , It is included in the scope and gist of the invention, and is also included in the scope of the invention described in the claims and the equivalent scope thereof.

For example, the ultrasonic probes 21 and 51 are not limited to water-immersed ultrasonic probes, and may be ultrasonic probes that propagate ultrasonic waves using a liquid such as oil or alcohol as a medium.

1 ... Reactor pressure vessel, 2 ... Jet pump, 3 ... Jet pump beam (inspection object), 14 ... Top surface (scratch detection surface), 15 ... Side surface (scratch detection surface), 17 ... Operation pole, 18 ... Detachment mechanism, 20 ... Beam top surface ultrasonic flaw detector, 21 ... Ultrasonic probe, 22 ... Device frame, 23 ... Fixing mechanism, 24 ... Positioning means, 25 ... Top surface first scanning mechanism, 26 ... Top surface second scanning mechanism, 27 ... Pole Connecting part, 32 ... worker, 36 ... contact sensor (detection means), 50 ... beam side surface ultrasonic flaw detector, 51 ... ultrasonic probe, 52 ... device frame, 53 ... side surface first scanning mechanism, 54 ... side surface 2nd scanning mechanism, 55 ... extension mechanism, 57 ... angle change mechanism

Claims (8)

An ultrasonic probe that propagates ultrasonic waves to the inspection object through a liquid without contacting the flaw detection surface of the inspection object.
A scanning mechanism installed on the device frame to move the ultrasonic probe in two directions orthogonal to the flaw detection surface to scan.
An ultrasonic flaw detector characterized by having a fixing mechanism for fixing and attaching the device frame to the inspection object. The ultrasonic flaw detector according to claim 1, further comprising a positioning means for positioning the posture of the device frame when the device frame is fixed to an object to be inspected by the fixing mechanism. The ultrasonic flaw detector according to claim 1 or 2, wherein the device frame is provided with a pole connecting portion in which an operation pole for hanging is detachably connected via a detachable mechanism. .. The ultrasonic flaw detector according to any one of claims 1 to 3, further comprising an extension mechanism capable of adjusting the distance between the ultrasonic probe and the flaw detection surface of the inspection object. 1 to claim 1, further comprising an angle changing mechanism for changing the angle of the ultrasonic probe in order to make it possible to adjust the parallelism of the ultrasonic probe with respect to the flaw detection surface of the inspection object. 4. The ultrasonic flaw detector according to any one of 4. The ultrasonic flaw detector according to any one of claims 1 to 5, further comprising a detection means for detecting that the device frame or the fixing mechanism has come into contact with an object to be inspected. It is an inspection method of the jet pump beam that ultrasonically detects the jet pump beam, which is a part of the jet pump installed in the reactor pressure vessel.
Using the ultrasonic flaw detector according to any one of claims 1 to 6,
A method for inspecting a jet pump beam, which comprises ultrasonically detecting the entire volume of the jet pump beam in a state where the jet pump beam is installed in the reactor pressure vessel. Using a plurality of ultrasonic flaw detectors according to any one of claims 3 to 6,
A claim characterized in that ultrasonic flaw detection of a jet pump beam is performed by each ultrasonic flaw detector while remotely connecting and disconnecting each of these ultrasonic flaw detectors and an operation pole via an attachment / detachment mechanism. Item 7. The method for inspecting a jet pump beam according to Item 7.

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