JP2021167749A - Ultrasonic flaw detection device and ultrasonic flaw detection method - Google Patents

Abstract

To provide a flaw detection device which is the device for non-destructively inspecting soundness of a front surface and inner side of a structure material and which reliably detects a flaw in a portion with limited accessibility.SOLUTION: An ultrasonic flaw detection device 100 detects a flaw by defining respective welding parts 14, 16 of two plates 13, 15 mutually attached at an interval by confrontation as an inspection object. The ultrasonic flaw detection device 100 includes: at least one probe 111 having a plurality of ultrasonic elements aligned in a longitudinal direction; a probe holding drive mechanism 120 for holding the probe and moving it by driving; and an ultrasonic flaw detector 113 for driving reception/transmission of an ultrasonic wave by the probe 111 so as to perform signal processing based on a reflection wave from the inspection object. The probe holding drive mechanism 120 includes: a short axis inclination correction section for performing driving to change a short axis inclination being a circumferential direction angle with respective longitudinal directions of the probe as axes; and a long axis inclination correction section for performing driving to change a long axis inclination being an angle with respect to the longitudinal directions of the probe.SELECTED DRAWING: Figure 1

Description

Embodiments of the present invention relate to ultrasonic flaw detectors and ultrasonic flaw detectors.

Ultrasonic flaw detection test is a technology that can confirm the soundness of the surface and inside of structural materials in a non-destructive manner, and is an indispensable inspection technology in various fields. Phased Array Ultrasonic Test (PAUT) that can form an arbitrary waveform by arranging small piezoelectric elements for transmitting and receiving ultrasonic waves and transmitting ultrasonic waves by shifting the timing (delay time) for each piezoelectric element. Is also widely used in industrial applications. Compared to a monocular probe that can emit ultrasonic waves only at a predetermined angle, it can detect a wide range with one flaw detection, can detect flaws at multiple angles, and can handle complicated shapes depending on the beam control. It is extensible.

Japanese Patent No. 4096014

Recently, large-scale power plants such as nuclear power and thermal power plants and social infrastructure equipment are aging, and the number of parts to be inspected and the types of defects to be detected are increasing compared to the past.

The parts that have been required to be inspected so far are designed for inspection in the first place, or the inspection target is exposed due to the limit of workability (welding, etc.). It was the majority. On the other hand, due to aging, risks have become apparent in parts that were not supposed to be inspected, and such targets are not subject to UT at the time of manufacture, and the shape of the inspection target position is complicated due to integral forging or the like. In some cases, UT cannot be applied by the usual method. For example, the joint of the riser brace arm that holds the jet pump in the reactor with the reactor pressure vessel is a part of normal all-around welding, but it is often used to detect flaws from inside the reactor with limited accessibility. The degree to which the flaw detection posture is required becomes large, and the burden on the device becomes large in order to cope with this. In other words, if there are many requests for flaw detection attitudes, the equipment may become complicated and it may not be possible to enter the narrow part of the reactor, or if the equipment is replaced for each attitude to avoid it, the inspection will be enormous. It will be costly.

However, on the other hand, when trying to detect a defect (crack) orthogonal to the weld line of the welded part, the only way to detect the flaw is to install a probe directly above the welded part, and an increase in man-hours in the furnace can be avoided. No.

A technique for detecting a weld in the reactor from outside the reactor pressure vessel of a boiling water reactor is known, but the target is limited to the vessel penetration (stub tube). Further, when assuming the propagation path of ultrasonic waves, it is very difficult to make the ultrasonic waves reach the relevant part from the outside of the reactor pressure vessel, and there is a possibility that the desired flaw detection performance cannot be obtained.

Therefore, in the embodiment of the present invention, a portion having limited accessibility such as a joint portion of the riser brace arm holding the jet pump in the reactor with the reactor pressure vessel is surely formed in the reactor pressure vessel. The purpose is to detect flaws.

In order to achieve the above-mentioned object, in the ultrasonic flaw detector according to the present embodiment, an intermediate space is formed at intervals between the surfaces, and each welded portion of two plates attached to the same member by welding. An ultrasonic flaw detector that detects defects by targeting the inspection target, and is a probe holding drive mechanism that holds and moves at least one probe having a plurality of ultrasonic elements arranged in the longitudinal direction and the at least one probe. And an ultrasonic flaw detector that drives the transmission and reception of ultrasonic waves by the probe and performs signal processing based on the reflected wave from the inspection target, and the probe holding drive mechanism is each of the at least one probe. A short-axis tilt correction unit that drives the at least one probe so as to change the short-axis tilt, which is an angle in the circumferential direction of each of the at least one probes, and each of the at least one probe with respect to the longitudinal direction. It is characterized by having a long-axis tilt correction unit that drives so as to change the long-axis tilt, which is an angle.

It is a vertical cross-sectional view which shows the structure of the ultrasonic flaw detector which concerns on 1st Embodiment. It is a cross-sectional view taken along the line II-II of FIG. 1 showing the configuration of the ultrasonic flaw detector according to the first embodiment. It is sectional drawing which shows the structure in the vicinity of the probe of the probe and the probe holding operation mechanism in the ultrasonic flaw detector which concerns on 1st Embodiment. It is a perspective view which shows the riser brace arm of the riser tube as an example of the inspection target of the ultrasonic flaw detection apparatus which concerns on 1st Embodiment, and its attachment part. FIG. 6 is a plan view taken along the line VV of FIG. 6 showing an inspection target range of the ultrasonic flaw detector according to the first embodiment. FIG. 5 is a side view taken along the line VI-VI of FIG. 5 showing an inspection target range of the ultrasonic flaw detector according to the first embodiment. It is a conceptual plan view for demonstrating the welding reference line long side part of the welding part of the flat plate as the target part of the ultrasonic flaw detection apparatus which concerns on 1st Embodiment. It is a conceptual side view for demonstrating the welding reference line short side part of the welding part of the flat plate as the target part of the ultrasonic flaw detection apparatus which concerns on 1st Embodiment. It is a partial cross-sectional view which shows the peripheral part of the probe of the ultrasonic flaw detector and the probe holding drive mechanism which concerns on 1st Embodiment. It is a 1st partial cross-sectional view which shows the peripheral part of the probe of the ultrasonic flaw detector and the modification of the probe holding drive mechanism which concerns on 1st Embodiment. It is a 2nd partial cross-sectional view which shows the peripheral part of the probe of the ultrasonic flaw detector and the modification of the probe holding drive mechanism which concerns on 1st Embodiment. It is a conceptual plan view which shows the probe of the ultrasonic flaw detection apparatus which concerns on 1st Embodiment, and the ultrasonic wave which is incident on the inspection object. It is a conceptual cross-sectional view taken along the line XIII-XIII of FIG. 12 showing the probe of the ultrasonic flaw detector according to the first embodiment and the ultrasonic wave incident on the inspection target. It is a conceptual cross-sectional view taken along the line XIV-XIV of FIG. 12 showing the probe of the ultrasonic flaw detector according to the first embodiment and the ultrasonic wave incident on the inspection target. It is a top view in the vicinity of the third welding layer which shows the example of how to take the reference plane in the inspection target of the probe of the ultrasonic flaw detector which concerns on 1st Embodiment. It is a side view in the vicinity of the third welding layer which shows the example of how to take the reference plane in the inspection target of the probe of the ultrasonic flaw detector which concerns on 1st Embodiment. It is a top view which shows the case where the ultrasonic flaw detector which concerns on 1st Embodiment sets the welding reference line long side part of the weld part of a flat plate as the part to be inspected. It is a side view which shows the case where the ultrasonic flaw detector which concerns on 1st Embodiment sets the welding reference line long side portion of the welding portion of a flat plate as an inspection target portion. It is a conceptual perspective view which shows the relationship between the ultrasonic wave emitted from the probe of the ultrasonic flaw detection apparatus which concerns on 1st Embodiment, and a welding line. It is a conceptual plan view which shows the relationship between the ultrasonic wave emitted from the probe of the ultrasonic flaw detection apparatus which concerns on 1st Embodiment, and a welding line. It is a conceptual partial cross-sectional view which shows the 1st state explaining the method of determining the minor axis inclination by the installation angle determination part in the installation angle correction mechanism of the ultrasonic flaw detection apparatus which concerns on 1st Embodiment. It is a graph which shows the change of the ultrasonic signal intensity in the case of the 1st state explaining the method of determining the minor axis inclination by the installation angle determination part in the installation angle correction mechanism of the ultrasonic flaw detection apparatus which concerns on 1st Embodiment. It is a conceptual partial cross-sectional view which shows the 2nd state explaining the method of determining the minor axis inclination in the installation angle correction mechanism of the ultrasonic flaw detection apparatus which concerns on 1st Embodiment. It is a graph which shows the change of the ultrasonic signal intensity in the case of the 2nd state explaining the method of determining the minor axis inclination in the installation angle correction mechanism of the ultrasonic flaw detector which concerns on 1st Embodiment. It is a perspective view which shows the case where the vertical crack which extends in the direction orthogonal to the welding direction occurs in the inspection target part of the ultrasonic flaw detection apparatus which concerns on 1st Embodiment. It is a conceptual partial cross-sectional view which shows the 1st state explaining the method of determining the long axis inclination by the installation angle determination part in the installation angle correction mechanism of the ultrasonic flaw detection apparatus which concerns on 1st Embodiment. It is a graph which shows the change of the ultrasonic signal intensity in the case of the 1st state explaining the method of determining the long axis inclination by the installation angle determination part in the installation angle correction mechanism of the ultrasonic flaw detection apparatus which concerns on 1st Embodiment. FIG. 5 is a conceptual partial cross-sectional view showing a second state for explaining a method of determining a major axis inclination in the installation angle correction mechanism of the ultrasonic flaw detector according to the first embodiment. It is a graph which shows the change of the ultrasonic signal intensity in the case of the 2nd state explaining the method of determining the major axis inclination in the installation angle correction mechanism of the ultrasonic flaw detector which concerns on 1st Embodiment. It is a partial cross-sectional view of FIG. 2 which shows the structure of the ultrasonic flaw detection apparatus which concerns on 1st Embodiment. It is a flow chart which shows the procedure of the ultrasonic flaw detection method which concerns on 1st Embodiment. It is a vertical cross-sectional view which shows the structure of the ultrasonic flaw detector which concerns on 2nd Embodiment. It is a cross-sectional view taken along the line XXXIII-XXXIII of FIG. 32 showing the configuration of the ultrasonic flaw detector according to the second embodiment.

Hereinafter, the ultrasonic flaw detection device and the ultrasonic flaw detection method according to the embodiment of the present invention will be described with reference to the drawings. Here, the parts that are the same as or similar to each other are designated by a common reference numeral, and the description of superimposition will be omitted.

[First Embodiment]
FIG. 1 is a vertical cross-sectional view showing the configuration of the ultrasonic flaw detector 100 according to the first embodiment, and FIG. 2 is a cross-sectional view taken along the line II-II of FIG. Further, FIG. 3 is a cross-sectional view showing a configuration in the vicinity of the probe 111 of the ultrasonic flaw detector 100 and the probe 111 of the probe holding operation mechanism 120.

1 to 3 show a portion of the riser brace arm 10 (FIG. 4) provided inside the reactor pressure vessel 1 for attaching the ultrasonic flaw detector 100 according to the present embodiment to the inside of the reactor pressure vessel 1. An example is shown in which a flat plate 13 as a member, a flat plate welding layer 14 as a welded portion thereof, and a flat plate 15 and a flat plate welded layer 16 as a welded portion thereof are applied to a flaw detection device for flaw detection as an inspection target portion 18a. ing.

The reactor pressure vessel 1 has a reactor pressure vessel base material 1a and a reactor pressure vessel inner surface liner which is an overlay welded portion formed on the inner surface of the reactor pressure vessel base material 1a. Hereinafter, the inner surface liner of the reactor pressure vessel is referred to as a first welding layer 1b. On the surface of the first welding layer 1b, that is, the inner surface of the reactor pressure vessel 1, a second welding layer 12 having a rectangular shape having a size covering the attachment range of the riser brace arm 10 is formed.

The flat plate 13 is attached to the second welded layer 12 via the flat plate welded layer 14, and the flat plate 15 is attached via the flat plate welded layer 16. The flat plate 13 and the flat plate 15 immediately below the flat plate 13 form an intermediate space 17 sandwiched between them.

The ultrasonic flaw detector 100 includes a probe 111, a probe holding drive mechanism 120, an ultrasonic flaw detector 113, a monitoring operation unit 114, a mechanism control unit 115, a remote visual inspection unit 116, and an installation angle correction mechanism 130.

The installation angle correction mechanism 130 has an installation angle determination unit 131 and a correction operation unit 132 (see FIGS. 10 and 11), the details of which will be described later.

The probe 111 emits ultrasonic waves at a position facing the inspection target portion 18a and receives the ultrasonic waves.

The probe 111 has a configuration consisting of a mechanism for generating ultrasonic waves, a damping material for damping ultrasonic waves, and a front plate attached to the oscillation surface of ultrasonic waves, or a combination thereof, and is generally ultra-ultrasonic. It is called a sound wave probe. As a mechanism for generating ultrasonic waves, a piezoelectric element made of ceramics, a composite material, or other material capable of generating ultrasonic waves by a piezoelectric effect, a piezoelectric element made of a polymer film, or other ultrasonic waves can be generated. Has an element.

Further, the probe 111 is not limited to the one having only one piezoelectric element, and generally, the piezoelectric element is arranged one-dimensionally in a linear array probe, and the piezoelectric element has a non-uniform size in the depth direction of the linear array probe. 1.5-dimensional array probe divided by, matrix array probe in which piezoelectric elements are arranged two-dimensionally, ring array probe in which ring-shaped piezoelectric elements are arranged concentrically, piezoelectric elements of ring array probe are arranged in the circumferential direction. Divided split ring array probes, non-uniform array probes in which piezoelectric elements are non-uniformly arranged, arc-shaped array probes in which elements are arranged in the circumferential position of an arc, spherical array probes in which elements are arranged on the surface of a spherical surface, etc. It may be an array probe of another shape.

The probe 111 is deviced by caulking or packing, and includes a probe 111 that can be used in air or in water.

Although not shown, when installing the probe 111, a wedge may be used to inject a highly directional angle into the inspection target portion 18a. A wedge is an isotropic material that can propagate ultrasonic waves and whose acoustic impedance can be grasped. As the wedge, there are acrylic, polyimide, gel, other polymers, etc., and the acoustic impedance is close to or the same material as the front plate, or the acoustic impedance is close to or the same material as the object to be inspected. You can also. Further, it may be a composite material in which the acoustic impedance is changed stepwise or gradually. In addition, a damping material may be arranged inside or outside the wedge so that the multiple reflection waves in the wedge do not affect the flaw detection result, a mountain-shaped wave-eliminating shape may be provided, or a multiple reflection reduction mechanism may be provided.

The probe 111 and the wedge, the wedge and the inspection target portion 18a, or the probe 111 and the inspection target portion 18a need to be acoustically coupled by an acoustic contact medium (not shown). The acoustic contact medium is a medium capable of propagating ultrasonic waves, such as water, glycerin, machine oil, castor oil, acrylic, polystyrene, and gel. When the space between the probe and the inspection target part is filled with a propagation medium as a completely underwater environment such as in a furnace, it is not necessary to use an acoustic contact medium separately.

The ultrasonic flaw detector 113 applies a potential difference for ultrasonic wave transmission to the probe 111, and performs processing such as amplification of a received signal of a reflected wave from the probe 111.

The ultrasonic flaw detector 113 has a function of applying a voltage of an arbitrary waveform, and the waveform of the applied voltage can be a sine wave, a sawtooth wave, a square wave, a spike pulse, or the like, and is a so-called bipolar having both positive and negative pole values. However, it may be a unipolar with either positive or negative swing. Further, an offset may be added to either positive or negative. Further, the waveform can be increased or decreased in application time and repetition frequency such as single pulse, burst or continuous wave. When an array probe is used for the probe 111, a mechanism for switching the timing according to the presence / absence of voltage application and the delay time for each channel can also be used.

The monitoring operation unit 114 has a display portion that displays the received waveform from the inspection target unit 18a output from the ultrasonic flaw detector 113 and the current position of the probe holding drive mechanism 120, and sets the conditions of the ultrasonic flaw detector 113. It is a user interface having an input portion capable of setting conditions for the probe holding drive mechanism 120 and inputting appropriate instructions. Here, the condition of the ultrasonic flaw detector 113 is, for example, the angle of incidence of the ultrasonic wave on the inspection target portion 18a, and the condition of the probe holding drive mechanism 120 is, for example, the designation of the angle direction with the assumed defect to be flawed. be.

The display portion of the monitoring operation unit 114 may be a so-called PC monitor, TV, projector, smartphone, tablet terminal, etc., as long as it can display digital data, and is displayed after being converted into an analog signal once like a cathode ray tube. It may be combined with the measuring instrument screen itself such as an oscilloscope or an oscilloscope. Further, the display portion may have a so-called user interface function of generating an alarm by sound or light emission according to a set condition or inputting an operation as a touch panel.

The mechanism control unit 115 adjusts the interrelationship between the operations of the above units, controls the progress of the entire process, and the like. The mechanism control unit 115 is a device having a function of performing general-purpose calculation and data communication as typified by a so-called PC, and has a configuration in which a part or all of the above-described configuration can be included or connected by a communication cable. ..

As described above, the monitoring operation unit 114 and the mechanism control unit 115 may be a computer system, or may be configured by combining a plurality of devices such as a PC, a monitor, and a control panel.

The remote visual inspection unit 116 (FIG. 1) is a so-called camera, which has a function of being used underwater because the inside of the reactor pressure vessel 1 is filled with water, or is placed in a waterproof mechanism. Etc. may be used. As the installation means, installation, transportation by a robot such as a drone, transportation by human power, etc. can be considered, and other general means may be used. Further, a plurality of remote visual inspection units 116 may be used, and all types, transportation methods, and the like can be used in combination.

The probe holding drive mechanism 120 moves the probe 111 to a position facing the inspection target portion 18a, and the posture of the probe 111 so that the ultrasonic wave receiving / transmitting surface of the probe 111 faces the measurement target portion 18a. It also functions as a part of the installation angle correction mechanism 130 for adjusting. Therefore, the probe holding drive mechanism 120 operates three-dimensionally. That is, each drive unit and support shaft having the functions of translational movement drive in the three-axis direction and rotation drive around the three axes are provided, if necessary. Further, it has a gap sensor (not shown) that measures the distance between the probe 111 and the inspection target portion 18a in order to maintain the distance between the probe 111 and the inspection target portion 18a at a predetermined value.

The installation angle correction mechanism 130 has an installation angle determination unit 131 and a correction operation unit 132. The installation angle determination unit 131 and the correction operation unit 132 will be described later.

The probe holding drive mechanism 120 includes a support portion 121, a short axis tilt correction unit 122, a long axis tilt correction unit 123, and a probe holding unit 125.

FIG. 3 shows the access shafts 121b and 121c and the final shaft 121a of the support portions 121 of the probe holding drive mechanism 120. The final shaft 121a is supported by the access shaft 121b, and the access shaft 121b is supported by the access shaft 121c. The probe 111 is held by the probe holding portion 125. The probe holding unit 125 is supported by the short-axis tilt correction unit 122, and the short-axis tilt correction unit 122 is supported by the long-axis tilt correction unit 123.

The major axis tilt correction unit 123 is supported by the final axis 121a. The short-axis tilt correction unit 122 rotates in the circumferential direction around the axis so as to correct the short-axis tilt of the probe 111, which will be described later. Further, the long-axis tilt correction unit 123 rotates in the circumferential direction around the axis so as to correct the long-axis tilt of the probe 111, which will be described later. Therefore, the final shaft 121a is not a linear motion shaft that expands and contracts in the longitudinal direction, but a rotary shaft that supports the rotating portion. The final shaft 121a may also be a type of rotation shaft that itself rotates about an axis in the longitudinal direction.

The portion of each member up to the final shaft 121a and the probe 111 supported by the final shaft 121a is inserted into the intermediate space 17 sandwiched between the upper flat plate 13 and the lower flat plate shown in FIG. 1 to perform an operation necessary for flaw detection.

As shown in FIG. 1, the flat plate 13 and the flat plate 15 are arranged in a substantially horizontal direction. Therefore, the flat plate 13 and the flat plate 15 are arranged vertically in parallel with each other, and in detail, the parallelism is about ± 10 degrees. The distance between the surfaces of the flat plate 13 and the flat plate 15, that is, the distance between the lower surface of the flat plate 13 and the upper surface of the flat plate 15, in other words, the height of the intermediate space 17 is about 76 mm.

The probe 111 and the short-axis tilt correction unit 122 and the long-axis tilt correction unit 123, which will be described later, adjust the tilt of the probe 111 to the final shaft 121a and the probe 111 supported by the probe 111 in order to detect the upper and lower inspection target portions. The portion of each member is inserted into the intermediate space 17 sandwiched between the upper flat plate 13 and the lower flat plate 15 and is formed in a size capable of adjusting. Therefore, the portion of each member up to the final shaft 121a and the probe 111 supported by the final shaft 121a is configured to have a width of about 60 mm in the vertical direction by ensuring a clearance of several mm in the vertical direction.

FIG. 4 is a perspective view showing a riser brace arm of a riser tube and an attachment portion thereof as an example of an inspection target of the ultrasonic flaw detector according to the first embodiment. In FIG. 4, of the two flat plates, the display on the lower flat plate 15 side is omitted, and only the upper flat plate 13 side is displayed.

As described above, the reactor pressure vessel 1 includes the reactor pressure vessel base material 1a and the meat applied to the inner surface of the reactor pressure vessel inner surface liner (first welding layer) 1b, that is, the reactor pressure vessel base material 1a. It has a filling welded part.

The reactor pressure vessel base material 1a is mainly low alloy steel, but may be general carbon steel, austenitic stainless steel, nickel-based alloy, or other metal.

The first welding layer 1b may be TIG welding, MIG welding, MAG welding, shielded metal arc welding, laser welding, submerged arc welding, electroslag welding, etc., and the material is generally austenite-based stainless steel, nickel-based alloy, and the like. Carbon steel, low alloy steel, etc. may be used. Further, when the overlay is performed in a plurality of layers, different materials and construction methods may be used in a desired layer such as an initial layer.

Further, the construction method and materials of the second welding layer 12 formed on the surface of the inner surface liner of the reactor pressure vessel, which is the first welding layer 1b, are the same as those of the first welding layer 1b.

In a boiling water reactor, a riser pipe 11 which is a pipe on the supply side of the reactor coolant to a jet pump (not shown) is attached to the inner wall of the reactor pressure vessel 1 by a riser brace arm 10. Of the riser brace arms 10, the flat plate 13 and the flat plate 15 (FIG. 1) are directly attached to the inner wall of the reactor pressure vessel 1.

The flat plate 13 and the flat plate 15 are attached by welding. Further, on the surface of the first welding layer 1b (inner surface of the reactor pressure vessel 1), a flat plate-shaped second welding layer 12 is further formed on the flat plate 13 and the mounting portion of the flat plate 15. There is. Therefore, a first welding layer 1b, a second welding layer 12, and a third welding layer, a flat plate welding layer 14, are formed on the mounting portion of the flat plate 13. Further, a first welding layer 1b, a second welding layer 12, and a third welding layer, a flat plate welding layer 16, are formed on the mounting portion of the flat plate 15.

Here, the flat plate welded layer 14 which is the third welded layer is a complete penetration welded portion by the groove of full penetration. The predetermined range from the weld metal end portion may be an arbitrarily determined range as long as it is equal to or less than the total length of the flat plate 13, and for example, 1 inch or 25 mm, 2 inches or 50 mm or the like may be a range required for ultrasonic flaw detection. The same applies to the flat plate welded layer 16 of the flat plate 15.

FIG. 5 is a plan view taken along the line VV of FIG. 6 showing an inspection target range of the ultrasonic flaw detector according to the first embodiment, and FIG. 6 is a side view taken along the line VI-VI line of FIG. ..

As shown in FIGS. 5 and 6, the inspection target range 18 includes the flat plate welding layer 14 for the flat plate 13 and the portion of the flat plate 13 in the vicinity of the flat plate welding layer 14, and the flat plate welding layer 16 and the flat plate 15 for the flat plate 15. It is a portion of the flat plate 15 in the vicinity of the flat plate welded layer 16. Here, for example, the portion in the vicinity of the flat plate welding layer 14 is a portion within a predetermined distance from the surface of the second welding layer 12. Here, the predetermined range may be any range as long as it is equal to or less than the total length of the plate material, and may be a range required for ultrasonic flaw detection, for example, 1 inch or 25 mm, 2 inches or 50 mm. The same applies to the portion in the vicinity of the flat plate welded layer 16.

FIG. 7 is a conceptual plan view for explaining a welding reference line long side portion 20a of the flat plate welding layer 14 of the upper flat plate 13 as a target portion of the ultrasonic flaw detector according to the first embodiment. , Is a conceptual side view for explaining the welding reference line short side portion 20b of the flat plate welding layer 14 of the upper flat plate 13.

The flat plate 13 is a plate having a rectangular cross section, and has two wide long side side surfaces 13a and two narrow short side side surfaces 13b. The side portion of the flat plate welding layer (third welding layer) 14 along the long side side surface 13a is the side along the flat plate welding long side portion 14a and the flat plate welding layer (third welding layer) 14 along the short side side surface 13b. Is referred to as a flat plate welding short side portion 14b.

Here, the welding reference line 20 is defined. There are two types of welding reference line 20: a welding reference line long side portion 20a and a welding reference line short side portion 20b.

As shown in FIGS. 7 and 8, the welding reference line long side portion 20a is a virtual line on the surface of the flat plate welding long side portion 14a. The boundary line between the long side side surface 13a and the flat plate welding long side portion 14a and the intersection line with the second welding layer 12 when the long side side surface 13a is virtually extended toward the second welding layer 12. The line in which the virtual line at the intermediate position is shifted to the surface of the flat plate welding long side portion 14a is defined as the welding reference line long side portion 20a. Here, the method of shifting shall be performed by moving in a state parallel to the second welding layer 12.

Similarly, the welding reference line short side portion 20b is an imaginary line on the surface of the flat plate welding short side portion 14b. The boundary line between the short side side surface 13b and the flat plate welding short side portion 14b and the intersection line with the second weld layer 12 when the short side side surface 13b is virtually extended toward the second weld layer 12. The line in which the virtual line at the intermediate position is shifted to the surface of the flat plate welding short side portion 14b is defined as the welding reference line short side portion 20b. Here, the shifting method is similarly performed by moving in a state parallel to the second welding layer 12.

Alternatively, the welding reference line 20 is the surface bead width of both stumps, assuming that the flat plate welding layer (third welding layer) 14 is cut at the extension surfaces of the long side side surface 13a and the short side side surface 13b of the flat plate 13. It may be defined as a line segment connecting midpoints.

In the set of the third welding layer 14 and the flat plate 13, the welding reference line 20 has a total of four lines, one on the front and back sides of the flat plate welding long side portion 14a and one front and back sides of the flat plate welding short side portion 14b. Will have.

FIG. 9 is a partial cross-sectional view showing a peripheral portion of the probe 111 of the ultrasonic flaw detector 100 according to the first embodiment.

The probe holding drive mechanism 120 includes a support portion 121, a short axis tilt correction unit 122, a long axis tilt correction unit 123 (FIG. 30), and a probe holding unit 125.

The support portion 121 supports the probe 111 so that the probe 111 is located in the inspection target range 18. The support portion 121 is coupled to a drive device (not shown) so that the portion of the support portion 121 that supports the probe 111 moves, and is moved and driven.

The short-axis tilt correction unit 122 is arranged near the end of the support unit 121 on the probe 111 side, and is configured to be able to rotate on the short-axis side in order to adjust the angle of the probe holding unit 125 on the short-axis side. ing. Here, the rotation on the short axis side is a rotation on a cross section perpendicular to the longitudinal direction of the probe 111.

The long-axis tilt correction unit 123 will be described later with reference to FIG. 30.

The probe holding unit 125 has a function of holding the probe 111. The probe holding portion 125 may have a function of holding a wedge or an acoustic contact medium.

The mechanism control unit 115 (FIG. 1) determines the position of the probe 111 by the support unit 121 and the direction of the probe 111 by the short axis tilt correction unit 122 in response to the designation of the inspection target unit 18a by the monitoring operation unit 114 or the like. Then, the probe 111 is controlled so as to face the position and direction of the inspection target portion 18a.

Here, the probe holding unit 125 and the minor axis tilt correction unit 122 may have a stage in which the probe 111 is held. The stage may be a stage whose position can be changed such as a linear motion stage, a stage whose angle can be changed such as a rotary stage or a goniometer stage, or a combination thereof. Further, those swimming in water, those swimming in the air like a drone, those having a multi-axis articulated arm, those having a humanoid shape, and those in which they are combined may be used.

The short axis tilt correction unit 122 rotates the probe 111 while ensuring a distance from the inspection target unit 18a.

FIG. 10 is a first partial cross-sectional view showing a peripheral portion of a modified example of the probe and the probe holding drive mechanism of the ultrasonic flaw detector according to the first embodiment, and FIG. 11 is a second partial cross-sectional view.

In the probe holding drive mechanism 120a according to the modified example, the probe holding portion 125 is provided with the spring 124. The spring 124 is arranged between the probe holding portion 125 and the probe 111, and the distance between the probe 111 and the probe holding portion 125 changes due to the expansion and contraction of the spring 124.

FIG. 10 shows a state in which the probe 111 is separated from the third weld layer 14. On the other hand, FIG. 11 shows a state in which the probe 111 is in close contact with the surface of the third welding layer 14. When the probe 111 is pressed against the surface of the third welding layer 14, the minor axis tilt correction unit 122 shifts to a free state without resisting the rotational force from the outside. This transition is switched when it detects that the spring has contracted by a predetermined value. As a result, the probe 111 is pressed against the surface of the third welding layer 14, so that the surface of the probe 111 is oriented so as to be along the surface of the third welding layer 14. The portion to be pressed may be the probe 111 main body, an accompanying wedge, a spacer provided separately, or the like.

As described above, the correction of the probe 111 in the direction along the surface by pressing it against the inspection target is the operation of the correction operation unit 132 of the installation angle correction mechanism 130. In this case, the probe holding with the spring 124 is held. The drive mechanism 120 is also a correction operation unit 132.

FIG. 12 is a conceptual plan view showing a probe of the ultrasonic flaw detector according to the first embodiment and ultrasonic waves incident on an inspection target, and FIG. 13 is a cross-sectional view taken along the line XIII-XIII of FIG. 14 is a cross-sectional view taken along the line XIV-XIV of FIG.

The flaw detection surface 111s (FIGS. 13 and 13) of the probe 111 is divided into two axes, a major axis direction (x direction) for refracting ultrasonic waves and a minor axis direction (y direction) for refracting ultrasonic waves. FIG. 13 is a cross-sectional view on the yz plane along the short axis direction, and FIG. 14 is a cross-sectional view on the xz plane along the long axis direction. The ultrasonic tonic line 52 emitted from the probe 111 toward the inspection target 51 travels in the inspection target 51 after being refracted by the reference plane P. As shown in FIG. 14, the tonic line U can be divided into a tonic line horizontal component Uh, which is a component in the x direction, and a tonic line vertical component Uv, which is a component in the z direction.

Here, the relationship between the reference plane P and the probe is defined as shown in FIGS. 12 to 13.

In the cross section of FIG. 13, the angle formed by the perpendicular line drawn from the reference surface P and the flaw detection surface 111s of the probe 111 is defined as the minor axis inclination γ. Further, in FIG. 14, the angle formed by the perpendicular line drawn from the reference surface P and the flaw detection surface 111s is defined as the major axis inclination φ. The rotation angle is controlled by the short-axis tilt correction unit 122 by controlling the short-axis tilt γ.

FIG. 15 is a plan view of the vicinity of the third welding layer showing an example of how to take a reference surface in the inspection target of the probe of the ultrasonic flaw detector according to the first embodiment, and FIG. 16 is a side view. Regarding the reference surface P, for example, as shown in FIGS. 15 and 15, the surface on which ultrasonic waves are incident from the probe 111, such as the surface of the flat plate welding long side portion 14a of the third welding layer 14, is set as the reference surface P. Is desirable.

However, since the surface of the welded portion such as the flat plate welded long side portion 14a is often hand-finished by a grinder or the like, it may be a surface having curvature or unevenness. Hereinafter, for convenience of explanation, the reference plane P is regarded as a plane.

In FIGS. 15 and 15, a plane passing through the boundary line between the welding long side portion 14a of the third welding layer 14 and the surface of the flat plate 13 and the boundary line between the welding long side portion 14a and the second welding layer 12 is used as a reference. It is the surface P. The reference plane P may be approximated in this way, or another plane may be taken depending on the coordinate system to be managed, such as the lowermost surface of the probe.

FIG. 17 is a plan view showing a case where the ultrasonic flaw detector according to the first embodiment uses the long side of the welding reference line of the welded portion of the flat plate as the inspection target portion, and FIG. 18 is a side view.

When the weld long side portion 14a of the third weld layer 14 is detected as the inspection target portion 18a as shown in FIGS. 17 and 17, the ultrasonic waves incident from the probe are the weld long side of the third weld layer 14. Incident from the surface of the part 14a, the tonic line U can be divided into a tonic line horizontal component Uh and a tonic line vertical component Uv as shown in FIG. The tonic line horizontal component Uh is a two-dimensional component obtained by projecting the tonic line U onto the reference plane P.

FIG. 19 is a conceptual perspective view showing the relationship between the ultrasonic waves emitted from the probe of the ultrasonic flaw detector according to the first embodiment and the welding line, and FIG. 20 is a plan view. In the examples shown in FIGS. 19 and 19, the tonic line U travels along the xz plane. On the other hand, the welding line 53 extends in the x direction. That is, as shown in FIG. 20, in the plan view, that is, in the state of being projected on the reference plane P, the tonic line U and the welding line 53 extend in substantially the same x direction. Now, when the angle between the welding line 53 projected on the reference plane P and the horizontal component Uh of the tonic line U is within the range of 0 ° ± ΔΦ, it is said that the flaw detection condition in the direction parallel to the welding line 53 is satisfied. It shall be. Here, ΔΦ is, for example, a value of about 20 °.

Here, in order to maximize the flaw detection sensitivity, it is necessary to control the minor axis inclination γ to 90 ° (perpendicular to the flaw detection surface 111s) as much as possible. This control is performed by the installation angle correction mechanism 130.

As described above, the installation angle correction mechanism 130 (FIG. 1) has an installation angle determination unit 131 and a correction operation unit 132.

The installation angle determination unit 131 determines whether or not the minor axis inclination γ and the major axis inclination Φ (FIG. 26) are within the permissible range. When the installation angle determination unit 131 does not determine that the minor axis inclination γ or the major axis inclination Φ is within the allowable range, the correction operation unit 132 shifts these within the allowable range.

The determination and correction of the minor axis inclination γ will be described below. The major axis inclination Φ will be described later with reference to FIGS. 26 to 30.

The installation angle determination unit 131 determines based on the level of the reflected signal of ultrasonic waves, as will be described with reference to FIGS. 21 to 24 below.

FIG. 21 is a conceptual partial cross-sectional view showing a first state for explaining a method of determining a minor axis inclination by the installation angle determination unit 131 in the installation angle correction mechanism 130, and FIG. 22 is a case of the first state. It is a graph which shows the change of the ultrasonic signal intensity of. In FIG. 22, the horizontal axis is the time axis and the vertical axis is the ultrasonic signal intensity. The intensity range Ap in which the intensity level is larger than A1 and smaller than A2 indicates the intensity range when the minor axis inclination γ is within the permissible range.

Now, let the reference plane P be the plane shown in FIGS. 15 and 15. Further, in the cross section of FIG. 21, the direction perpendicular to the reference plane is indicated by the vertical line Q.

In this first state, the direction of the tonic line U of the ultrasonic wave emitted from the probe 111 is substantially the same as the direction of the vertical line Q. That is, the minor axis inclination γ ₁ is approximately 90 °. Therefore, even after the ultrasonic waves enter the third welding layer 14, the tonic line does not refract significantly and passes through the range of the inspection target portion 18a of the third welding layer 14.

When incident at such a preferable angle, as shown in FIG. 22, the intensity of the ultrasonic waves reflected on the surface of the third welding layer 14 becomes a value larger than the predetermined intensity level A1. Further, when the reflected wave has such an intensity, the arrival time of the reflected wave is within a predetermined arrival time range Tp. Therefore, when the intensity of the reflected wave is within the intensity range Ap or when the arrival time is within the predetermined arrival time range Tp, it is determined that the minor axis inclination γ is within the permissible range.

FIG. 23 is a conceptual partial cross-sectional view showing a second state for explaining a method of determining the minor axis inclination by the installation angle determination unit 131 in the installation angle correction mechanism 130, and FIG. 24 is a case of the second state. It is a graph which shows the change of the ultrasonic signal intensity of.

In this second state, the direction of the tonic line U of the ultrasonic wave emitted from the probe 111 is not in a range that substantially coincides with the direction of the vertical line Q. That is, the minor axis inclination γ ₂ is an angle that cannot be said to be approximately 90 °. Therefore, after the ultrasonic wave enters the third welding layer 14, the tonic line is greatly refracted and is substantially out of the range of the inspection target portion 18a of the third welding layer 14.

When the incident is incident at a deviation from such a preferable angle, as shown in FIG. 24, the intensity of the ultrasonic wave reflected on the surface of the third welding layer 14 does not reach the predetermined intensity level A1 and the reflected wave does not reach the predetermined intensity level A1. The strength is out of the strength range Ap. Further, in such a case, the arrival time of the reflected wave is delayed from the predetermined arrival time range Tp. Therefore, when the intensity of the reflected wave is out of the intensity range Ap or when the arrival time is later than the predetermined arrival time range Tp, it is determined that the minor axis inclination γ is out of the permissible range.

Here, the allowable range of the minor axis inclination γ can be set by evaluating in advance whether or not the direction of the tonic line is within the range of the inspection target portion 18a. Based on this result, the intensity range Ap and the arrival time range Tp can also be set in advance.

The determination by the installation angle determination unit 131 in the installation angle correction mechanism 130 is performed based on the difference in the magnitude and propagation time of the reflected wave as described above, and the determination is automatically performed by the installation angle determination unit 131. Since each result is also displayed on the display unit of the monitoring operation unit 114, the inspector or the like may make a judgment by looking at the displayed waveform.

In addition to the above method, the installation angle determination unit 131 may determine using a non-contact distance measuring means such as a laser range finder, an ultrasonic range finder, or a camera. Alternatively, mechanical contact means such as a limit switch or a spacer may be used. These may be attached to the probe 111 itself, or may be attached to the probe holding portion 125 or the structure itself. As the installation angle determination unit 131, a plurality of types and installation locations can be used in combination.

As a result of measurement by the installation angle determination unit 131, if the short axis tilt γ is not within the predetermined range, the short axis tilt correction unit 122 is used as the correction operation unit 132 to adjust the short axis tilt γ. It can be corrected.

Alternatively, the correction operation unit 132 can correct the minor axis inclination γ by the method shown in FIGS. 10 and 10.

The correction operation unit 132 not only corrects the direction, that is, the minor axis inclination γ by pressing it against the inspection target unit, but also corrects the probe holding unit 125 and the minor axis inclination γ by using a rotation mechanism such as a rotation stage or a goniometer stage. The final γ may be set to a desired angle by having the unit 122 hold it and controlling them.

FIG. 25 is a perspective view showing a case where a vertical crack 14d extending in a direction orthogonal to the welding direction occurs in the inspection target portion of the ultrasonic flaw detector according to the first embodiment.

As shown in FIG. 25, the installation angle correction mechanism 130 as described above is used to detect fatigue cracks that propagate in the direction orthogonal to the welding direction in the third welding layers 14 and 16, that is, so-called vertical cracks. .. It is also effective in detecting various welding defects such as poor fusion, blow holes, slag entrainment, and cracks generated over time such as stress corrosion cracking. It is also effective for detecting defects peculiar to nuclear reactors such as hydrogen flaking. Cracks and the like other than the above-mentioned welding defects can extend from the third welding layer 14 or the third welding layer 16 to the upper flat plate 13 or the lower flat plate 15, but are also effective for such cracks. ..

Next, the determination and correction of the major axis inclination Φ will be described.

The installation angle determination unit 131 determines based on the level of the reflected signal of ultrasonic waves, as will be described with reference to FIGS. 26 to 29 below.

FIG. 26 is a conceptual partial cross-sectional view showing a first state for explaining a method of determining a major axis inclination by the installation angle determination unit 131 in the installation angle correction mechanism 130, and FIG. 27 is a case of the first state. It is a graph which shows the change of the ultrasonic signal intensity of. Further, FIG. 28 is a conceptual partial cross-sectional view showing a second state, and FIG. 29 is a graph showing a change in ultrasonic signal intensity in the second state. The cross sections of FIGS. 26 and 28 show a cross section along the longitudinal direction of the probe 111, that is, the direction in which the ultrasonic elements are arranged, and perpendicular to the reference plane P.

In FIGS. 27 and 29, the horizontal axis is the time axis and the vertical axis is the ultrasonic signal intensity. The intensity range Ap in which the intensity level is larger than A1 and smaller than A2 indicates the intensity range when the major axis inclination Φ is within the permissible range.

The major axis inclination Φ is the angle formed by the straight line perpendicular to the reference surface P and the flaw detection surface 111s of the probe 111 in this cross section, as described with reference to FIG. Here, the reference plane P is, for example, the plane shown in FIGS. 15 and 15.

When the major axis inclination Φ1 in the first state is appropriate, as shown in FIG. 27, the intensity of the ultrasonic waves reflected on the surface of the third welding layer 14 becomes a value larger than the predetermined intensity level A1. Further, when the reflected wave has such an intensity, the arrival time of the reflected wave is within a predetermined arrival time range Tp. Therefore, when the intensity of the reflected wave from the reference plane P is within the intensity range Ap or when the arrival time is within the predetermined arrival time range Tp, it is determined that the major axis inclination Φ is within the permissible range.

On the other hand, when the major axis inclination Φ2 in the second state is not appropriate, the intensity of the ultrasonic waves reflected on the surface of the third welding layer 14 does not reach the predetermined intensity level A1 as shown in FIG. 29. It becomes a value. Further, in the case of such a reflected wave, the arrival time of the reflected wave is delayed from the predetermined arrival time range. Therefore, similarly to the determination of the minor axis inclination γ, when the intensity of the reflected wave is out of the intensity range Ap or when the arrival time is behind the predetermined arrival time range Tp, it is determined that the major axis inclination Φ is out of the allowable range. Will be done.

As with the determination of the minor axis inclination γ, the determination by the installation angle determination unit 131 may be a determination using another method.

FIG. 30 is a partial cross-sectional view of FIG. 2 showing the configuration of the ultrasonic flaw detector according to the first embodiment.

As shown in FIG. 30, the long-axis tilt correction unit 123 included in the probe holding drive mechanism 120 is located between the support unit 121 and the short-axis tilt correction unit 122, and serves as a correction operation unit 132 in the longitudinal direction of the probe holding unit 125. Adjust the tilt of.

As a result of the measurement by the installation angle determination unit 131, when the long-axis inclination Φ is not within the predetermined range, the long-axis inclination correction unit 123 of the correction operation unit 132 can correct the long-axis inclination Φ. As the correction operation unit 132, another method may be used on the long axis side as well as on the short axis side.

FIG. 31 is a flow chart showing the procedure of the ultrasonic flaw detection method according to the first embodiment. In FIG. 31, the procedure is shown by taking the case of performing flaw detection from the intermediate space 17 as an example.

First, the probe 111 held by the probe holding unit 125, the short-axis tilt correction unit 122 for adjusting the inclination thereof, and the long-axis tilt correction unit 123 are inserted into the intermediate space 17 sandwiched between the upper flat plate 13 and the lower flat plate 15. , Install (step S10).

Next, the minor axis side adjustment is performed (step S20). Specifically, first, the installation angle determination unit 131 of the installation angle correction mechanism 130 makes a measurement for determining the minor axis inclination γ (step S21), and the installation angle determination unit 131 allows the minor axis inclination γ. It is determined whether or not it is within the value (step S22).

When it is not determined that the short-axis tilt γ is within the permissible value (step S22 NO), the short-axis tilt correction unit 122 as the correction operation unit 132 of the installation angle correction mechanism 130 adjusts the short-axis tilt γ. (Step S23), steps S21 to S23 are repeated.

When it is determined that the minor axis inclination γ is within the permissible value (step S22 YES), the next major axis side adjustment is performed (step S30). Specifically, first, the installation angle determination unit 131 of the installation angle correction mechanism 130 makes a measurement for determining the major axis inclination Φ (step S31), and the installation angle determination unit 131 allows the major axis inclination Φ. It is determined whether or not it is within the value (step S32).

If it is not determined that the major axis tilt Φ is within the permissible value (step S32 NO), the minor axis tilt correction unit 122 as the correction operation unit 132 of the installation angle correction mechanism 130 adjusts the major axis tilt Φ. (Step S33), steps S21 to S23 are repeated.

When it is determined that the major axis inclination Φ is within the permissible value (step S32 YES), the inspection target is detected (step S40).

In the above procedure, the first probe 111a and the second probe 111b are arranged in the intermediate space 17 sandwiched between the upper flat plate 13 and the lower flat plate 15, and the inspection target portion 18a of the upper flat plate 13 is viewed from below and below. The case where the inspection target portion 18b of the flat plate 15 is detected from above has been described as an example, but the case where the upper flat plate 13 is detected from above and the lower flat plate 15 is detected from below is usually because there are few restrictions on arrangement. Can be detected.

As described above, according to the present embodiment, the reactor pressure is applied to a portion having limited accessibility such as a joint portion of the riser brace arm 10 holding the jet pump in the reactor with the reactor pressure vessel 1. The flaw can be reliably detected in the container 1.

[Second Embodiment]
FIG. 32 is a vertical cross-sectional view showing the configuration of the ultrasonic flaw detector according to the second embodiment, and FIG. 33 is a cross-sectional view taken along the line XXXIII-XXXIII of FIG. 32.

The second embodiment is a modification of the first embodiment, and the probe holding drive mechanism 120a in the present embodiment is of the first probe 111a and the second probe 111b supported by the final shaft 121a of the support portion 121. It has two probes.

The probe holding drive mechanism 120a is configured to be able to detect flaws in the upper and lower parts of the intermediate space 17 sandwiched between the upper plate 13 and the lower plate 15.

Specifically, the first probe 111a detects the vicinity of the third weld layer 14 of the upper flat plate 13. While the first probe 111a is held by the probe holding portion 125a, the minor axis tilt correction unit 122a adjusts the minor axis tilt γ, and the major axis tilt correction unit 123a adjusts the major axis tilt Φ.

Further, the second probe 111b detects the vicinity of the third weld layer 16 of the lower flat plate 15. The second probe 111b is held by the probe holding unit 125b, and the minor axis tilt correction unit 122b adjusts the minor axis inclination γ, and the major axis inclination correction unit 123b adjusts the major axis inclination Φ.

The first probe 111a held by the probe holding unit 125a and the short axis tilt correction unit 122a and the long axis tilt correction unit 123a for adjusting the inclination thereof, and the second probe 111b held by the probe holding unit 125b and its inclination are adjusted. The short-axis tilt correction section 122b, the long-axis tilt correction section 123b, and the final shaft 121a that supports them are an intermediate space sandwiched between the upper flat plate 13 and the lower flat plate 15 in order to detect the upper and lower inspection target portions. It is formed in a size that can be inserted into the 17 and adjusted. Specifically, it is configured to have a vertical width of about 60 mm, as in the large embodiment.

As described above, according to the present embodiment, it is possible to reliably detect a portion having limited accessibility in the same manner.

[Other Embodiments]
Although the embodiments of the present invention have been described above, the embodiments are presented as examples and are not intended to limit the scope of the invention.

Moreover, you may combine the features of each embodiment. In addition, the 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.

The embodiments and modifications thereof are included in the scope and the gist of the invention as well as the invention described in the claims and the equivalent scope thereof.

1 ... Reactor pressure vessel, 1a ... Reactor pressure vessel base material, 1b ... Reactor pressure vessel inner surface liner (first welding layer), 10 ... Riser brace arm, 11 ... Riser tube, 12 ... Second welding layer , 13 ... Upper flat plate, 13a ... Long side side surface, 13b ... Short side side surface, 14 ... Flat plate welding layer (third welding layer), 14a ... Flat plate welding long side portion, 14b ... Flat plate welding short side portion, 14d ... Vertical Crack defect, 15 ... lower flat plate, 15a ... long side side surface, 15b ... short side side surface, 16 ... flat plate welding layer (third welding layer), 17 ... intermediate space, 18 ... inspection target range, 18a ... inspection target part, 20 ... Welding reference line, 20a ... Welding reference line long side, 20b ... Welding reference line short side, 51 ... Inspection target, 52 ... Main sound line, 53 ... Welding line, 100, 100a ... Ultrasonic flaw detector, 110 ... Weld detection mechanism, 111 ... probe, 111a ... first probe, 111b ... second probe, 111s ... flaw detection surface, 113 ... ultrasonic flaw detector, 114 ... monitoring operation unit, 115 ... mechanism control unit, 116 ... remote visual inspection unit, 120 , 120a ... Probe holding drive mechanism, 121 ... Support portion, 121a ... Final axis, 121b, 121c ... Access shaft, 122, 122a, 122b ... Short axis tilt correction unit, 123, 123a, 123b ... Long axis tilt correction unit, 124 ... Spring, 125, 125a, 125b ... Probe holding unit, 126 ... Access drive unit, 130 ... Installation angle correction mechanism, 130 ... Installation angle correction mechanism, 131 ... Installation angle determination unit, 132 ... Correction operation unit

Claims (9)

It is an ultrasonic flaw detector that detects defects by forming an intermediate space between the surfaces and inspecting each welded part of two plates attached to the same member by welding.
With at least one probe having multiple ultrasonic elements arranged in the longitudinal direction,
A probe holding drive mechanism that holds and moves at least one probe,
An ultrasonic flaw detector that drives the transmission and reception of ultrasonic waves by the probe and performs signal processing based on the reflected wave from the inspection target.
With
The probe holding drive mechanism is
A short-axis tilt correction unit that drives to change the short-axis tilt, which is an angle in the circumferential direction of the probe with respect to the longitudinal direction of the probe.
A long-axis tilt compensator that drives to change the long-axis tilt, which is an angle with respect to the longitudinal direction of the probe,
An ultrasonic flaw detector characterized by having. The ultrasonic flaw detector according to claim 1, further comprising a short-axis tilt determining unit for determining whether or not the short-axis tilt is within an allowable range. The second aspect of the present invention is the second aspect of the present invention, further comprising a short-axis tilt correction unit capable of adjusting the short-axis tilt when the short-axis tilt determination unit determines that the short-axis tilt is not within an allowable range. Ultrasonic flaw detector. The ultrasonic flaw detector according to any one of claims 1 to 3, further comprising a long-axis tilt determining unit for determining whether or not the long-axis tilt is within an allowable range. The fourth aspect of claim 4 is characterized in that it further includes a short-axis tilt correction unit capable of adjusting the long-axis tilt when the long-axis tilt determination unit determines that the long-axis tilt is not within an allowable range. Ultrasonic flaw detector. The at least one probe is two, the first probe is the welded portion of the first plate of the two plates, and the second probe is the welded portion of the second plate of the two plates. The ultrasonic flaw detector according to any one of claims 1 to 5, wherein each of the above can be inspected at the same time. The probe holding drive mechanism supports the short-axis tilt correction unit and the long-axis tilt correction unit, and has a plurality of support shafts configured in series.
Of the probe, the short-axis tilt correction unit, the long-axis tilt correction unit, and the plurality of support portions, at least the final supporting the probe, the short-axis tilt correction unit, and the long-axis tilt correction unit. The ultrasonic flaw detector according to any one of claims 1 to 6, wherein the shaft is accessible between the two plates. One of claims 1 to 7, wherein the two plates form a riser brace arm and are attached to the inner surface of the member by welding with the reactor pressure vessel as the member. The ultrasonic flaw detector according to paragraph 1. This is an ultrasonic flaw detection method in which defects are detected by forming the intermediate space between the surfaces and welding each welded portion of two plates attached to the same member by welding.
An installation step in which the probe held by the probe holding portion and the short-axis tilt compensator and the long-axis tilt compensator for adjusting the tilt thereof are inserted and installed in the intermediate space.
The short-axis tilt correction unit that drives the short-axis tilt correction unit that drives to change the short-axis tilt that is the angle in the circumferential direction of each of the at least one probe about the longitudinal direction of each of the at least one probe is the short-axis tilt of the short-axis tilt. The minor axis side adjustment step for adjustment and
A long-axis tilt correction unit that drives each of the at least one probe so as to change the long-axis tilt, which is an angle with respect to the longitudinal direction, adjusts the long-axis tilt.
A flaw detection step for detecting the inspection target and
An ultrasonic flaw detection method characterized by having.

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