Ultrasonic inspection instrument

The present invention relates to the field of ultrasonic flaw detection technology.

Two probes, a probe for transmitting ultrasonic waves and a probe for receiving ultrasonic waves, are fixedly arranged at regular intervals, and defects in the body to be inspected using the TOFD (Time of Flight Diffraction) method. The existence of a device that detects ultrasonic waves, and the provisions of the TOFD method are stipulated in the British standard BS7706 (1993), and in the TOFD method, the ultrasonic waves emitted from the transmitter probe are used as the subject to be inspected. It is said that the incident angle was set to 45 to 55 degrees, and the receiving angle to receive the diffracted wave from the defect tip in the inspected body based on the ultrasonic wave with the receiving probe was also set to 45 to 55 degrees. It is known (see, for example, Patent Document 1).

On the other hand, there is a concern that the intensity of the diffracted wave will decrease due to the spread of the transmitted ultrasonic beam and the defect detectability will decrease. It is known that the diffracted wave is efficiently detected by focusing and irradiating the defect tip with the diffracted wave detection region of the receiving probe (Patent Document 1 and Patent Document 2).

It is well known that the incident angle of ultrasonic waves is preferably 45 degrees for efficient detection of diffracted waves (see, for example, Patent Document 2, pages 4-5, FIG. 2).

Furthermore, a group of vibrators in which a plurality of vibrating elements are assembled as a row of transmitting vibrators and a train of receiving vibrators mounted in the same casing is used, and a delay circuit is used for each of the vibrating elements of the vibrator group. By connecting the above and gradually shifting the excitation timing of each vibrating element by the delay circuit, the refraction angle of the ultrasonic wave is finely adjusted by electronic scanning performed while controlling the traveling direction of the ultrasonic wave, and the defect depth. It is known to make measurements (see, for example, pages 3-6 of Patent Document 3, FIGS. 1 to 12).

<p><patcit num="1"><text>Japanese Unexamined Patent Publication No. 2001-228128 (Pages 2-4, Fig. 1-Fig. 8)</text></patcit><patcit num="2"><text>Japanese Unexamined Patent Publication No. 2001-228126 (Pages 4-5, Fig. 1-Fig. 4)</text></patcit><patcit num="3"><text>JP-A-2002-62281 (pages 3-6, Fig. 1-Fig. 12)</text></patcit></p>

<p> In these conventional examples, ultrasonic flaw detection is performed by the TOFD (Time of Flight Diffraction) method in which two probes, an ultrasonic transmission probe and a reception probe, are fixed at regular intervals. Furthermore, the incident angle of ultrasonic waves was set at 45 to 55 degrees, and the receiving angle was also set at 45 to 55 degrees. The reason for defining this angle as 45 degrees to 55 degrees has been generally used because it is considered that the diffracted wave obtained by irradiating the defect tip with an ultrasonic beam is strong in the direction of 45 degrees to 55 degrees. Because it is.</p><p> However, in the TOFD method in which the incident angle of ultrasonic waves is set to about 45 to 55 degrees and for reception is also set to about 45 to 55 degrees, the ultrasonic transmission probe and reception probe are set to about 45 to 55 degrees. In order to maintain the transmission / reception angle, the distance between the ultrasonic transmission probe and the reception probe is fixed and arranged at a wide fixed interval, and the outer dimensions of the ultrasonic transmission probe and the reception probe are combined. Due to its large size, it cannot be applied to ultrasonic flaw detection inspections in inspection areas or narrow areas where the contact area of each transmitter / receiver probe is small, and the path length of ultrasonic waves from transmission to reception of ultrasonic waves becomes long and super. There was a problem that the ultrasonic reception intensity was weakened.</p><p> Therefore, an object of the present invention is to reliably detect defects from a shallow position to a deep position of an inspection object, and more preferably, ultrasonic flaw detection is surely performed even on an inspection object having a large ultrasonic attenuation. To be able to do it.</p>

<p> In order to achieve the above object, as a transmission / reception array sensor of the ultrasonic flaw detector, a transmission oscillator train in which a plurality of transmission vibration elements for transmitting ultrasonic waves are arranged and a plurality of reception vibration elements for receiving ultrasonic waves. The vibrating elements of each vibrating element are 0.1 mm to 2 mm in width, and the vibrating elements adjacent to each other in each vibrating element are 0.05 mm to 0.05 mm. We propose the configuration of an ultrasonic transmission / reception array sensor that is arranged with a gap of 0.2 mm. Further, in addition to the configuration, it is preferable to install a friction reducing means in contact with the inspection object in the transmission / reception array sensor while avoiding the entrance / exit surface of ultrasonic waves.</p><p> Further, as an ultrasonic flaw detector, a control for focusing each ultrasonic wave transmitted from each of the transmitting vibration elements at a focusing position where half of the sum of the ultrasonic transmission angle and the ultrasonic reception angle is within 30 degrees. We propose a configuration including an apparatus, a generation means for generating flaw detection information based on the ultrasonic waves received by the reception vibration element, and a display means for displaying the flaw detection information generated by the generation means.</p><p> Further, as an ultrasonic flaw detection method, both a transmitter row in which a plurality of transmission vibration elements for transmitting ultrasonic waves are arranged and a receiver transducer row in which a plurality of reception vibration elements for receiving ultrasonic waves are arranged. The transmission / reception array sensor with the above transmits / receives ultrasonic waves to the object to be inspected, and focuses the ultrasonic waves at a focusing position where half of the sum of the ultrasonic transmission angle and the ultrasonic reception angle related to the transmission / reception is within 30 degrees. We propose an ultrasonic flaw detection method that controls the ultrasonic flaw detector.</p>

<p> According to the present invention, ultrasonic flaw detection can be reliably performed even under conditions where the ultrasonic diffraction intensity is weak.</p>

<figref num="1">The whole view of the ultrasonic flaw detector according to the Example of this invention.</figref><figref num="2">FIG. 5 is an operation flowchart of an ultrasonic flaw detector according to an embodiment of the present invention.</figref><figref num="3">The timing chart figure of the transmission ultrasonic oscillator control signal to each vibrating element.</figref><figref num="4">The generation timing chart of the transmitted ultrasonic wave.</figref><figref num="5">The figure which exemplifies the output display example 1 (A scan signal) of the defect signal in the Example of this invention.</figref><figref num="6">Both figures (a) and (b) are explanatory diagrams of the definitions of the ultrasonic transmission angle θt and the reception angle θr.</figref><figref num="7">An explanatory diagram of the definitions of the width / depth / height of the small array sensor with integrated transmission / reception, the element width / element length of the ultrasonic oscillator, and the width of the insulating material.</figref><figref num="8">Structural drawing of a small array sensor with integrated transmission and reception.</figref><figref num="9">Another structural diagram of a small array sensor with integrated transmission and reception.</figref><figref num="10">FIG. 2 is an output display example 2 of a defect signal of the present invention, in which an image displayed on a display device of an ultrasonic flaw detector is printed on paper by a printer.</figref><figref num="11">The illustration of the output display example 3 of the defect signal of this invention.</figref><figref num="12">FIG. 4 is an output display example 4 of a defect signal of the present invention, in which an image displayed on a display device of an ultrasonic flaw detector is printed on paper by a printer.</figref><figref num="13">FIG. 5 is an output display example 5 of a defect signal of the present invention, in which an image displayed on a display device of an ultrasonic flaw detector is printed on paper by a printer.</figref><figref num="14">The figure which shows an example which applied the ultrasonic flaw detector of this invention to defect detection and defect sizing.</figref><figref num="15">The figure which shows another example which applied the ultrasonic flaw detector of this invention to defect detection and defect sizing.</figref><figref num="16">The figure which showed the application of the transmission / reception integrated small array sensor to the shroud support part in the nuclear reactor of this invention for each case.</figref><figref num="17">The figure when the present invention is applied to the vicinity of the CRD housing stub tube and the nuclear pressure vessel at the bottom of the reactor.</figref><figref num="18">The figure in the case where the transmission / reception integrated small array sensor of this invention is mounted on the suspension type inspection apparatus.</figref><figref num="19">FIG. 1 is a diagram of Example 1 in which the transmission / reception integrated small array sensor of the present invention is applied to a concave-shaped inspection target portion.</figref><figref num="20">FIG. 2 is a diagram of Example 2 in which the transmission / reception integrated small array sensor of the present invention is applied to a concave-shaped inspection target portion.</figref><figref num="21">FIG. 1 is a diagram of Example 1 in which the transmission / reception integrated small array sensor of the present invention is applied to an inspection target portion having a convex diameter shape.</figref><figref num="22">FIG. 2 is a diagram of Example 2 in which the transmission / reception integrated small array sensor of the present invention is applied to an inspection target portion having a convex diameter shape.</figref><figref num="23">The figure of the figure of the example of the follow-up mechanism to the concave-convex surface diameter shape of the transmission / reception integrated compact array sensor of this invention.</figref><figref num="24">The figure which shows another example which applied the ultrasonic flaw detector of this invention to defect detection and defect sizing.</figref><figref num="25">The figure of the Example of the simple inspection apparatus in a nuclear reactor using the ultrasonic flaw detector of this invention.</figref><figref num="26">The figure of the Example of the inspection apparatus in a nuclear reactor using the ultrasonic flaw detector of this invention.</figref>

In the ultrasonic flaw detection method in the embodiment of the present invention, it is possible to widen the intersection region of the focusing points of transmission and reception by using a region where the incident angle of transmission and reception of ultrasonic waves to the material to be inspected is 30 degrees or less. Therefore, it was possible to significantly reduce the fluctuation of the defect detection sensitivity due to a slight misalignment between the focusing point of the transmitting ultrasonic wave and the focusing point of the received ultrasonic wave.

<p> The inventors have arranged an array type transmission ultrasonic oscillator (also referred to as a transmission array sensor) having a transmission oscillator array in which a plurality of ultrasonic vibration elements are arranged, and a receiver in which a plurality of ultrasonic vibration elements are arranged. A small array sensor with integrated transmission / reception (hereinafter, simply a transmission / reception array sensor or sensor) in which an array type transmission / reception ultrasonic oscillator (also referred to as a reception array sensor) having a series of oscillators is housed in one casing and integrally molded. (Abbreviated as) was manufactured. The inventors use this sensor to focus both the transmission and reception of ultrasonic waves, and set the transmission / reception angles of ultrasonic waves, which were conventionally considered difficult to detect diffracted waves, to 0, respectively. Defects in the inspection object were irradiated with ultrasonic waves at a temperature of ~ 30 degrees, and defect detection and defect sizing tests were conducted.</p><p> As a result, the inventors have clarified for the first time that defect flaw detection and defect sizing can be carried out satisfactorily. That is, it was discovered that defect flaw detection and defect sizing are possible even when the ultrasonic transmission / reception angle is as shallow as 30 degrees or less, which was conventionally 45 to 55 degrees.</p><p> That is, it was possible to establish a new ultrasonic flaw detection method different from the conventional TOFD method in which the ultrasonic transmission / reception angle is 45 to 55 degrees. This new ultrasonic flaw detection method can widen the intersection area of the transmission and reception focusing points by using a region where the incident angle of transmission and reception is 30 degrees or less, and the transmission and reception focusing points and the received ultrasonic waves can be widened. It is possible to significantly reduce the fluctuation of the defect detection sensitivity due to a slight misalignment of the focusing point, and to realize the so-called robustness of the defect detection sensitivity, which has the feature that defect detection and defect sizing can be stably performed. It came to.</p><p> By using this new ultrasonic flaw detection method, defect detection and defect sizing were not possible with the conventional edge echo method and TOFD method. (1) The defect width is narrow and the ultrasonic diffraction intensity is weak. Defects, (2) Defects in materials with large ultrasonic attenuation and anisotropic materials that bend ultrasonic waves, (3) Defects in inspection areas and narrow areas where the contact area of the probe is small, (4) Welding Defect detection and defect sizing of defects in metal could be realized.</p><p> Specific examples for realizing this new ultrasonic flaw detection method will be described below. FIG. 1 shows the entire ultrasonic flaw detector of the present invention. The ultrasonic flaw detector according to the embodiment of the present invention is roughly divided into an ultrasonic flaw detector main body 122 and a transmission / reception array sensor 14 (hereinafter, simply a sensor) electrically connected to the ultrasonic flaw detector main body 122 by each signal line. It is called 14). Each of the signal lines is bundled into a signal cable 123.</p><p> The sensor 14 transmits ultrasonic waves 16 from the vibrating elements A, B, C, and D of the transmission vibrator train 15 constituting the transmission array sensor into the inspection target material 21 which is an inspection target, and the ultrasonic waves 16 are transmitted. In each vibrating element O, P, Q, R of the receiving vibrator row 19 constituting the receiving array sensor, the diffracted wave generated by the ultrasonic wave 16 diffracting at the lower end of the defect 22 in the material 21 to be inspected based on It receives and outputs the electrical signal generated in each vibrating element by receiving the diffracted wave from each vibrating element in the receiving vibrator train 19 to the ultrasonic flaw detector main body 122. Since the vibrating elements A, B, C, and D of the transmitting oscillator row 15 are used for transmission, they are transmitting vibrating elements, and the vibrating elements O, P, Q, and R of the receiving oscillator row 19 are for receiving. It can be defined as a receiving vibration element because it is used for.</p><p> The sensor 14 including the transmitting oscillator row 15 and the receiving oscillator row 19 as a unit is placed on the surface of the material 21 to be inspected so that the central portion of the sensor 14 is located directly above the defect 22.</p><p> The ultrasonic flaw detection device main body 122 receives an electric signal from each vibrating element of the receiving oscillator row 19 and creates an inspection result as an ultrasonic flaw detection result. The ultrasonic flaw detector main body 122 includes an input device 1, a memory 2, an ultrasonic control device 3, an information processing device 4, an I / O 5, a display device 6, a transmitting side amplifier control device 9, a receiving side amplifier control device 10, and a transmission. It has an ultrasonic transducer control device 7, a reception signal processing device 8, a transmission side amplifier 11, and a reception side amplifier 12.</p><p> A detailed description of each of these devices and the role of the device will be described below. FIG. 1 shows an overall view of an ultrasonic flaw detector according to an embodiment of the present invention. FIG. 2 describes the flow of operation steps in the embodiment of the present invention.</p><p> First, the input device 1 is used to input the input conditions for determining the ultrasonic transmission / reception pattern (step a). The input condition is a condition for determining an ultrasonic transmission / reception pattern for detecting defects with high sensitivity, and is (1) a transmission oscillator sequence (denoted as an excitation element sequence in FIG. 2). Vibrating elements A, B, C, D, (2) Vibrating elements O, P, Q, R of the receiving oscillator sequence (denoted as receiving element sequence in Fig. 2), (3) Transmission ultrasonic focusing point Position (F11, F12, ..., Fmn, m = 1 ~ i, n = 1 ~ j), (4) Position of receiving focus point (F11, F12, ..., Fmn, m = 1 ~ i) , N = 1 ~ j), (5) gain representing the amplification degree of the transmitting side amplifier 11, (6) gain representing the amplification degree of the receiving side amplifier 12, and the like. This input condition is transferred from the input device 1 to the memory 2 and the ultrasonic controller 3 (step b).</p><p> In the ultrasonic control device 3, the ultrasonic transmission timing Ttimn and the reception timing Trimn of each ultrasonic vibrator such that the ultrasonic waves are focused at each ultrasonic focusing point are calculated from the input conditions (step c). Here, Tt: transmission ultrasonic delay time, Tr: reception delay time, i: vibrating element number (A, B, C, .........), mn: two-dimensional coordinates.</p><p> Transmits ultrasonic control signals necessary to operate each vibrating element A, B, C, D of the transmitting oscillator train and the vibrating elements O, P, Q, R of the receiving oscillator train. Ultrasonic oscillator control device 7 And it is transmitted from the ultrasonic control device 3 to the received signal processing device 8 via the I / O 5 (step d). The transmitting ultrasonic vibrator control signal (focusing point Fmn, initial value F11) is amplified by the transmitting side amplifier 11 and supplied to each vibrating element A, B, C, D of the transmitting vibrator train 15 (step e). ).</p><p> Since the ultrasonic waves 16 (spherical waves) emitted from the vibrating elements A, B, C, and D of the transmission oscillator row 15 have a time lag, at the position of the focusing point 17 (Fmn) inside the material 21 to be inspected. Each ultrasonic wave 16 is focused (step f). In FIG. 1, since the ultrasonic wave 16 is focused at the focusing point 17 (Fmn), the transmission signal to the vibrating element A existing near the outermost part of the sensor 14 farthest from the focusing point 17 (Fmn) is input earliest. The earliest ultrasonic waves are emitted from the vibrating element A. Further, the transmission signal to the vibrating element D existing near the center of the sensor 14 closest to the focusing point 17 (Fmn) is input at the latest, and the ultrasonic wave 16 is emitted from the vibrating element D at the latest.</p><p> Figure 3 shows the timing chart of the ultrasonic oscillator control signal transmitted to each vibrating element. In addition, FIG. 4 shows a generation timing chart of the ultrasonic wave 16 generated by FIG. As mentioned above, the delay time to each vibrating element A, B, C, D for focusing ultrasonic waves at the position of the focusing point 17 (Fmn) inside the material 21 to be inspected TrAmn, TrBAmn, TrCmn, ... is calculated by the ultrasonic controller 3. Therefore, since the ultrasonic wave 16 (spherical wave) has a time lag, the ultrasonic wave can be focused at the position of the focusing point 17 (Fmn) inside the material 21 to be inspected.</p><p> When there is a defect end at the focus point 17 (Fmn), the ultrasonic wave is diffracted at the defect end to generate a diffracted wave 18, and the diffracted wave 18 is the vibrating elements O, P, Q of the receiving transducer row 19. It is incident on R with a time lag (step g).</p><p> In FIG. 1, the diffracted wave 18 incident on the receiving vibration element O located near the center of the sensor 14 closest to the focusing point 17 (Fmn) is the earliest in time and is the farthest from the focusing point 17 (Fmn). The diffracted wave 18 incident on the receiving side vibrating element R existing near the outermost part of the sensor 14 is the slowest in time. When the diffracted wave 18 is incident on each vibrating element O, P, Q, R of the receiving vibrator row 19, the intensity and time of the diffracted wave 18 are applied to each vibrating element O, P, Q, R of the receiving vibrator row 19. The corresponding ultrasonic reception signal (electric signal) is induced, and this ultrasonic reception signal (electric signal) is amplified by the receiving side amplifier 12 and input to the receiving signal processing device 8 (step h) (here, here. The receiving side amplifier 12 and the receiving signal processing device 8 may be exchanged, the signals may be added by the receiving signal processing device 8 and combined into one signal, and then amplified by one of the receiving side amplifiers 12).</p><p> In the reception signal processing device 8, the reception focusing point 17 (Fmn) of each vibrating element O, P, Q, R of the receiving vibrator row 19 and each vibrating element O, P, Q, R of the receiving vibrator row 19 After controlling the reception timing Trimn that synthesizes each ultrasonic reception signal (electric signal) from the positional relationship (distance relationship), each ultrasonic reception signal (electric signal) is added to create one ultrasonic reception signal ( Step i). In the reception timing Trimn, the reception focusing points of the vibrating elements O, P, Q, and R of the receiving oscillator row 19 are focused on the receiving focusing point (same as the focusing point 17 (Fmn)) determined from the input conditions. Such a value is calculated by the ultrasonic control device 3.</p><p> The ultrasonic reception signal is transferred to the information processing device 204 and the memory 2 via the I / O 5 (step j). FIG. 5 shows a typical example when the ultrasonic wave reception signal obtained here is processed by the information processing device 4 according to the display form and displayed as flaw detection information by the display device 6. This signal display is called an A scope, and the horizontal axis displays the time of the ultrasonic reception signal (electric signal) and the vertical axis displays the intensity of the ultrasonic reception signal as flaw detection information. By displaying the defect diffracted wave signal as the flaw detection information as shown in FIG. 5, it is possible to recognize the existence of the defect diffracted wave signal as the basis for the existence of the defect and detect the defect. In addition, the depth of the defect can be measured (defect sizing) from the transmission time of the ultrasonic wave and the detection time of the diffracted wave (propagation time of the ultrasonic wave).</p><p> Since the diffracted wave 18 by the conventional ultrasonic flaw detection method is weak, in this embodiment, as described above, the transmitted ultrasonic wave is focused on the defect end and the receiving side is also focused to greatly improve the diffracted wave detection sensitivity. It is possible to improve. Moreover, by using a region where the ultrasonic wave transmission angle and the diffracted wave reception angle are 30 degrees or less, it is possible to widen the intersection region of the transmission and reception focusing points, making defect detection and defect sizing robust. It became possible to do. As described above, in the embodiment of the present invention, at least one ultrasonic focusing point is set in the region where the ultrasonic transmission / reception angle is 30 degrees or less, and all the points may be set as such.</p><p> In this way, the ultrasonic control device 3 calculates the ultrasonic transmission timing and the reception timing so that the focusing point of the ultrasonic wave 16 and the focusing point of the reception are at the same place, and the control signal is transmitted to the ultrasonic transducer control. It is given to the device 7 and the received signal processing device 8 for processing.</p><p> The operation of steps e to j above is performed when there are multiple focusing points (F11, F12, ..., Fmn, m = 1 ~ i, n = 1 ~ j) defined in two-dimensional coordinates. , Steps k, l, m, n, o after step j are executed for each of a plurality of focusing points. Finally, the information processing device 4 processes the received signal obtained by receiving the diffracted wave in step P so as to match the desired display form, and the information processing device is used to process the received signal as desired. The display device 6 displays an image as the flaw detection information in the display form, and processes and analyzes the received signal information (received data).</p><p> As described above, in the embodiment of the present invention, in order to realize the robust flaw detection method with small size, high sensitivity, high resolution resolution and defect detection, (1) in the ultrasonic flaw detection device, the transmission array sensor and the reception array sensor are used. There is an intersection of each focused sound field (focusing point 17), and the intersection of the focused sound fields is moved within the range where 1/2 of the sum of the transmission and reception angles of the ultrasonic waves is 30 degrees. , (2) The intersection of the focused sound field is the center of the transmitting array sensor and the receiving array sensor, and (3) The values of the ultrasonic transmission angle θt and reception angle θr are difficult to detect in the past. Using the region of 30 degrees or less that was considered (the transmission angle θt and the reception angle θr are set to include the region of 30 degrees or less, respectively), ultrasonic waves are transmitted / received to the defect, and the propagation time of the ultrasonic waves Perform defect detection and defect sizing tests, (4) Compact, compact array sensor (element width: 1.0 mm or less, insulating material width) suitable for transmission / reception integrated compact array sensors with small size, high sensitivity, and high resolution resolution. : 0.2mm or less) can be proposed.</p><p> Figures (a) and (b) of FIG. 6 show the definitions of the transmission angle θt of the ultrasonic wave 16 from the sensor 14 to the material 21 to be inspected and the reception angle θr of the diffracted wave 18 which is the ultrasonic wave to the sensor 14. The ultrasonic transmission angle θt is the line connecting the center of the transmission oscillator row 15 and the focusing point 17 (solid line in the figure), the center of the sensor 14 (between the transmitting oscillator row 15 and the receiving oscillator row 19), and the focusing point. It is defined as the angle formed by the line connecting 17 (broken line in the figure). The receiving angle θr is the line connecting the center of the receiving oscillator row 19 and the focusing point 17 (solid line in the figure), the center of the sensor 14 (between the transmitting oscillator row 15 and the receiving oscillator row 19), and the focusing point 17. It is defined as the angle formed by the connecting line (broken line in the figure).</p><p> In the embodiment of the present invention, there is an intersection (focusing point 17) of each focused sound field of the ultrasonic wave transmitted by the ultrasonic flaw detector and the ultrasonic wave received as a diffracted wave, and the ultrasonic wave with respect to the intersection of the focused sound field. The intersection of the focused sound fields is moved within the range where 1/2 of the sum of the transmission angle θt and the reception angle θr is 30 degrees or less. To execute this operation, the transmission ultrasonic focusing point (F11, F11,) is used as an input condition so that the position of the intersection of the focusing sound field is displaced within the range where the values of the transmitting angle θt and the receiving angle θr are 30 degrees or less, respectively. Enter F12, ..., Fmn, m = 1 ~ i, n = 1 ~ j) and the receiving intersection (F11, F12, ..., Fmn, m = 1 ~ i, n = 1 ~ j) However, it can be realized by executing the flow of the operation shown in FIG. 2 using the device shown in FIG.</p><p> FIG. 7 shows the width / depth / height of the sensor 14, and the element width / element length of the vibrating element that converts the electrical signal into ultrasonic waves, that is, the vibrating element that constitutes the transmitting oscillator row 15 and the receiving oscillator row 19. Definitions of sensors and insulation widths are illustrated.</p><p> In the embodiment of the present invention, a sensor 14 in which a transmission array sensor and a reception array sensor are compactly integrated is used, and the size of the sensor 14 is larger than the width of the inspection target portion or the weld metal portion which is the inspection target portion. It must be small or equivalent, and the width of the vibrating elements that make up the transmitter row 15 and receiver row 19 mounted on the sensor 14 must be at least twice or less than 40 times the distance between the elements. In particular, in an ultrasonic flaw detector used in a reactor, the contact area (footprint) of a small array sensor with integrated transmission / reception that directly contacts the weld metal part or base material that is the surface to be inspected is 30 mm in the width direction of the sensor 14. × The size of the sensor 14 is 30 mm or less in the depth direction, and the defect can be detected or sized by bringing the sensor 14 into direct contact directly above the defect in the welded metal part. Regarding the vibrating element of the sensor 14, when the element width exceeds 2.0 mm, the ultrasonic wave in the direct downward direction becomes stronger directly below and weakens in the lateral direction, and as a result, it becomes difficult to control the focusing of the ultrasonic wave. If the element width is less than 0.1 mm, the vibration focusing element width is set to 0.1 mm to 2.0 mm, considering that the energy of the ultrasonic waves that can be transmitted is weakened and it becomes difficult for the ultrasonic waves to be transmitted to a deep position. The width of the insulating material between the elements was 0.05 mm to 0.2 mm. In this way, the sensor 14 is configured in which the vibration element is compact and compact.</p><p> For example, the width of the vibration focusing element of the sensor 14 and the width of the insulating material between the vibration elements are such that the distance between each vibration element (ultrasonic vibrator) of the transmission vibrator row 15 and the reception vibrator row 19 is 1.0 mm (element width). : 0.8mm, Insulation width: 0.2mm), 8 elements for the transmitting oscillator row 15 and 8 elements for the receiving oscillator row 19, 16 elements in total, width: 1.0mm / element x 16 elements = 16mm, It was realized with an array probe with an element length of 10 mm. Further, the distance between each vibrating element (ultrasonic vibrator) of the transmitting vibrator row 15 and the receiving vibrator row 19 is set to 0.5 mm (element width: 0.4 mm, insulating material width: 0.1 mm), and the transmitting vibrator is set. Row 15 is 16 elements, receiver oscillator row 19 is 16 elements, 32 elements in total, width: 0.5 mm / element x 32 elements = 16 mm, element length: 10 mm array probe. Further, the distance between each vibrating element (ultrasonic vibrator) of the transmitting vibrator row 15 and the receiving vibrator row 19 is set to 0.25 mm (element width: 0.2 mm, insulating material width: 0.05 mm), and the transmitting vibrator is set. Row 15 is 32 elements, receiver oscillator row 19 is 32 elements, 64 elements in total, width: 0.25 mm / element x 64 elements = 16 mm, element length: 10 mm array probe. As a result, a sensor having a very small cross section (footprint) of the sensor 14 determined by the width and depth of the sensor 14 of about 16 mm in the width direction x 10 mm in the depth direction can be realized.</p><p> That is, in the embodiment of the present invention, a very small sensor having a cross-sectional area (footprint) of the sensor 14 of 30 mm in the width direction and 30 mm or less in the depth direction is used, and defect flaw detection and defect sizing can be realized with this small sensor 14. The width of a typical weld metal part in a nuclear reactor is about 20 to 50 mm, and considering contact on this, the footprint of the sensor 14 should be 30 mm in the width direction x 30 mm in the depth direction for inspection. Can be carried out satisfactorily.</p><p> In the above explanation, the expression "the contact area of the transmission / reception integrated small array sensor that directly contacts the weld metal part or the base material, which is the surface to be inspected, is as small as 30 mm x 30 mm or less" is used. In addition to the method of bringing the sensor 14 directly to the surface of the material to be inspected, it is also possible to carry out the partial water immersion method (water distance of 10 mm or less) used to avoid friction with the surface of the material to be inspected. Included as a meaning.</p><p> FIG. 8 shows an example of the structure of the sensor 14. The vibrating elements of the transmitting oscillator row 15 and the receiving oscillator row 19 are installed on the epoxy resin plate 101, which is the input / output surface for ultrasonic waves, and their positions are fixed by the resin 102. A sound insulating material 103 that absorbs ultrasonic waves is filled between the casing 100 and the resin 102. In another structural example of the sensor 14 in FIG. 9, each vibrating element of the transmitting oscillator row 15 and the receiving oscillator row 19 is installed on the epoxy resin plate 101, and a sound absorbing material 104 (cork material or the like) is placed between them. By installing it, the crosstalk of sound between the transmitting oscillator row 15 and the receiving oscillator row 19 can be significantly reduced, and noise can be reduced and the detection sensitivity can be further improved.</p><p> As will be described in detail in the examples described later, by using this apparatus configuration, it is possible to electronically scan the focusing point 17 in the direction directly below the center of the sensor 14, that is, to move the position of the focusing point 17. It becomes. FIG. 10 shows a typical example when the defect signal is displayed on the display device 6 as the flaw detection information obtained here. This signal display shows the defect depth, the horizontal axis is the distance in the direction in which the transmitter oscillator row 15 and the receiver oscillator row 19 of the transmission / reception integrated small array sensor 14 are lined up, and the vertical axis is the sensor 14. The distance in the bottom direction. The origin in FIG. 10 is the center of the reception array probe, and the signal strength when the ultrasonic wave reception angle is θr (the signal strength of the A scope is displayed as a shade image) is displayed. That is, the shading distribution on the two-dimensional coordinates represents the intensity of the ultrasonic reception signal (electric signal). Since it can be evaluated that the tip of the defect, which is the source (reflection source) of the ultrasonic wave, is located in the portion where the intensity of the ultrasonic wave reception signal (electric signal) is high, the defect can be sizing. As can be seen from FIG. 10, it is possible to visually recognize the tip of a defect, and the objectivity of defect detection and defect sizing can be improved.</p><p> FIG. 11 shows another display example of the ultrasonic flaw detector according to the embodiment of the present invention. Figure 11 shows an example when there are two defect tips. The A scope is displayed for each θr for the focal depths F11 (θr = θ1), F12 (θr = θ2), F13 (θr = θ3), F14 (θr = θ4) ... Fig. 11 shows the schematic waveforms of the A scopes of F11 (θr = θ1), F12 (θr = θ2), F13 (θr = θ3), and F14 (θr = θ4) at this time. Focusing on F11 (θr = θ1), the ultrasonic signal existing in the ultrasonic focusing point region is considered to be a defect indicator signal, and similarly, F12 (θr = θ2), F13 (θr = θ3), F14 (θr = θ4). ), Focusing on the ultrasonic focusing point region, gate the ultrasonic focusing point region and add all of them to obtain the A-scope waveform (AC scope) at the bottom. Since it can be recognized that the defect tip is located where the ultrasonic signal of the AC scope exists, defect detection and defect sizing are possible.</p><p> FIG. 12 shows another display example of the flaw detection information in the embodiment of the present invention. The signal display of this flaw detection information is for the purpose of objectively evaluating the defect depth. The horizontal axis is the defect depth ( ultrasonic wave reception signal time), and the vertical axis is the focusing pattern number. .. The focusing pattern number on the vertical axis is the transmitting ultrasonic focusing point (= receiving side focusing point) number and corresponds to F11, F12, F13, and F14. That is, FIG. 3c shows the signal intensities of the A scope corresponding to the vertical axis (focusing pattern number) displayed as a shade image. Since it can be evaluated that the portion where the intensity of the ultrasonic wave reception signal (electric signal) is high has the tip of the defect as the source (reflection source) of the ultrasonic wave which is a diffracted wave, the defect can be sizing. As can be seen from FIG. 12, it is possible to visually recognize the tip of a defect, and the objectivity of defect detection and defect sizing can be improved.</p><p> Under the flaw detection condition in which the focusing point 17 is electronically scanned in the direction directly below the center of the sensor 14, the sensor 14 is mechanically scanned (the transmitting oscillator train 15 of the sensor 14 and the vibrating elements of the receiving oscillator train 19 are arranged side by side. FIG. 13 shows a typical example when the display device 6 displays the flaw detection information including the defect signal when scanning in the horizontal direction orthogonal to the direction in which the sensor is located. The horizontal axis is the time of the ultrasonic reception signal (electric signal), the vertical axis is the distance in the scanning direction of the sensor 14, and the shading distribution on the two-dimensional coordinates represents the intensity of the ultrasonic reception signal (electric signal). is there. That is, it can be evaluated that the locally strong or high part of the ultrasonic reception signal (electric signal) has the tip of a defect which is the source (reflection source) of the ultrasonic wave which is a diffracted wave, and other stationary parts. Since it can be judged that the bottom echo is in the part where the intensity is high, it is possible to detect and size the defect.</p><p> The information of the received signal obtained by transmitting and receiving ultrasonic waves is visualized by the display device 6 as the flaw detection information by the display of any of FIGS. 10, 11, 12, and 13, and the flaw detection information is received. Based on the received signal sent from the signal processing device 8 to the memory 2 and stored, and the received signal sent to the information processing device 4, the information processing device 4 processes the flaw detection information suitable for the display form and displays the display device 6. Is displayed in.</p><p> In FIG. 1, the position of the lower tip of the defect 22 is generally known, and the input condition is that the focusing point 17 of the ultrasonic wave 16 is set to one point according to the position of the tip. A focusing point 17 of the ultrasonic wave 16 is set at the tip of the defect 22 (the lower end of the defect 22 in each figure) opened on the surface of the material 21 to be inspected, and the ultrasonic wave 16 is transmitted so as to be focused at the focusing point 17. Ultrasonic waves 16 are emitted from the vibrating elements A, B, C, and D of the vibrator train 15 to focus the ultrasonic waves 16 toward the focusing point 17 which is the tip of the defect 22. The focused ultrasonic wave 16 is diffracted at the tip of the defect 22 to generate a diffracted wave 18. The diffracted wave 18 is incident on and received on each of the vibrating elements O, P, Q, and R of the receiving oscillator train 19. When each vibrating element O, P, Q, R receives a diffracted wave, an ultrasonic reception signal (electrical signal) is output from each vibrating element O, P, Q, R and transmitted to the transmission / reception signal delay control device 7. After the amplification and delay processing are executed, the waveform of FIG. 5, which is an ultrasonic waveform, is displayed on the display device 6. The displayed content may be FIG. 10, FIG. 11, FIG. 13 or the like. This enables defect detection and defect sizing. Figure 1 describes the method when the tip of defect 22 is known to some extent. In this case, since the focusing point 17 is one place, it is not necessary to set a plurality of focusing points 17 and move the focusing point.</p><p> FIG. 14 shows another example in which the ultrasonic flaw detector according to the embodiment of the present invention is applied to defect detection and defect sizing. As described above, the method when the lower tip of the defect 22 is known to some extent has been described, but in the actual inspection, the opening of the defect 22 on the surface of the material 21 to be inspected by visual inspection using a camera or the like. In many cases, there is only initial information that there is. That is, the ultrasonic flaw detection test is often performed without knowing the depth of the defect 22, that is, the position of the lower end of the defect 22. FIG. 14 describes an example of performing an ultrasonic flaw detection test in a state where the depth of the defect 22 is unknown, and will be described in detail below.</p><p> The procedure for defect detection and sizing is described below using FIG. The sensor 14 is pressed directly above the defect 22 generated in the material 21 to be inspected, that is, against the opening of the defect 22 appearing on the surface of the material 21 to be inspected so that the central portion of the sensor 14 faces.</p><p> The alignment of the defect 22 and the sensor 14 is performed visually or by remote visual inspection using a camera and lighting, and the center of the sensor 14 and the opening of the defect 22 are aligned. That is, the sensor 14 is aligned directly above the defect 22 to perform defect detection and defect sizing.</p><p> Since the depth of the defect 22 cannot be visually determined from the opening side of the defect 22 existing on the surface of the material to be inspected, in this embodiment, the focusing point 17 (= ultrasonic focusing receiving point) of the transmitted ultrasonic wave 16 is defective. The sensor 14 is continuously or discretely scanned in the direction directly below the sensor 14, which is the depth direction of the sensor 14. Scanning directly below the sensor 14 at the focusing point 17 (= ultrasonic focusing receiving point) of the transmitting ultrasonic wave 16 controls the transmitting ultrasonic transducer control device 7 and the received signal processing device 8 using the ultrasonic control device 3. Since the ultrasonic focusing width has a finite size of about several millimeters, the diffracted wave 18 is generated by the interaction between the end of the defect 22 and the focused transmitted ultrasonic wave 16. The diffracted wave 18 is incident on the receiving transducer row 19, the ultrasonic reception signal (electric signal) is amplified by the receiving side amplifier 12, transmitted / signal synthesized to the receiving signal processing device 8, and stored or information processed in the memory 2. The signal is processed by the device 4. The ultrasonic waveform obtained here is shown in FIG. 5, and the outputs of defect detection and defect sizing are shown in FIGS. 10 and 13. This enables defect detection and defect sizing even when the depth of the defect 22 is unknown.</p><p> An example of changing the gain of the transmission amplifier according to the position (depth) of the focusing point 17 will be described with reference to FIGS. 14 and 1. In FIG. 14, the focusing point 17 is scanned in the order of F11 F12 F13 F14. Therefore, in the example of FIG. 14, four positions are set as input conditions for determining the ultrasonic transmission / reception pattern as the positions of the focus points 17 for transmission / reception.</p><p> In the vicinity of the inner surface layer (F11) of the focusing point 17 of the material 21 to be inspected, the propagation distance of ultrasonic waves is shorter than that in the deep point (F14), and the attenuation of ultrasonic waves in the material 21 to be inspected is small. ) Has high ultrasonic intensity. On the other hand, at the point where the focusing point is deep (F14), the propagation distance of the ultrasonic wave is long, the attenuation of the ultrasonic wave in the material 21 to be inspected is large, and the intensity of the ultrasonic wave is lower than that near the surface layer (F11). If the gain of the transmitting amplifier 11 is set according to the deep point (F14) of the focusing point, the gain is too high near the surface layer (F11) and the dead zone of the ultrasonic wave becomes large. Defects near the surface (F11) cannot be detected.</p><p> Therefore, in the vicinity of the surface layer (F11) of the material 21 to be inspected, the gain of the transmitting side amplifier 11 is set lower than that of the deep focusing point (F14). That is, in this embodiment, in order to give the optimum ultrasonic wave intensity to the focusing point depth, the ultrasonic wave control device 3 calculates and sets the optimum ultrasonic wave intensity to the focusing point depth, and controls the transmitting side amplifier through I / O5. The device 9 is controlled, and the gain of the transmitting amplifier 11 is changed according to the focusing point depth. Therefore, the ultrasonic control device 3 and the transmission side amplifier control device 9 also function as the first amplification degree control device. This enables defect detection and defect sizing in a wide range from the vicinity of the inner surface layer (F11) of the focusing point 17 in the material 21 to be inspected to the deep point (F14) of the focusing point.</p><p><tables num="1"><img file="JP4832550B2_D0001.tif" /></tables></p><p> Table 1 shows the gain settings of a typical transmitting amplifier 11. AT1 to AT4 are the names of each amplifier of the transmitting side amplifier 11, and one amplifier is connected to one vibrating element. F11 to F14 indicate the focusing points 17 for transmission and reception, and are F11 to F14 in order from the shallowest focusing point 17. The gain at a certain focusing point (F11 to F14) of each amplifier AT1 to AT4 is G. For example, the gain of the focusing point F11 of the amplifier AT1 is GA1, and the gain of the focusing point F14 is GD1. As shown in Table 1, the gain of each amplifier is optimized according to the focusing point depth, and the gain is set larger as the focusing point depth becomes deeper (GA &lt;GB &lt;GC &lt;GD). To do.</p><p> In the above, an example of the embodiment in which the gain of the transmitting amplifier is changed according to the depth of the focusing point 17 is shown, but this effect can also be realized by changing the gain of the receiving amplifier 12 according to the depth of the focusing point 17. There is, and an example thereof will be described below. In the vicinity of the surface layer (F11) of the material to be inspected 21, the propagation distance of the ultrasonic waves is shorter than that of the deep point (F14), and the attenuation of the ultrasonic waves in the material 21 to be inspected is small. High strength. On the other hand, at the point where the focusing point is deep (F14), the propagation distance of the ultrasonic wave is long, the attenuation of the ultrasonic wave in the material 21 to be inspected is large, and the intensity of the ultrasonic wave is lower than that near the surface layer (F11). If the gain of the receiving amplifier 12 is set according to the deep point (F14) of the focusing point, the gain is too high near the surface layer (F11), and the defect near the surface layer (F11) of the material 21 to be inspected is accurate. Cannot be detected.</p><p> Therefore, the gain of the receiving side amplifier 12 is set lower near the surface layer (F11) of the material 21 to be inspected than the deep focusing point (F14). That is, since the feature of the present invention is to give the optimum ultrasonic detection sensitivity to the focusing point depth, the ultrasonic control device 3 calculates the optimum ultrasonic detection sensitivity to the focusing point depth and sets the gain of the receiving side amplifier 12. Then, the receiving side amplifier control device 10 is controlled through the I / O 5, and the gain of the receiving side amplifier 12 is changed according to the focusing point depth. Therefore, the ultrasonic control device 3 and the receiving side amplifier control device 10 also function as the second amplification degree control device.</p><p> This makes it possible to detect defects from the vicinity of the surface layer (F11) of the material 21 to be inspected to the deep point (F14) of the focusing point. Table 2 shows the gain settings of a typical receiving amplifier 12. AR1 to AR4 are the names of the receiving amplifiers 12 to which one receiving amplifier 12 is connected to each vibrating element in the receiving oscillator train. F11 to F14 indicate the focusing point 17, and the focusing point 17 F11 to F14 in order from the shallowest. The gain at a certain focusing point (F11 to F14) of each amplifier (AR1 to AR4) is G. For example, the gain of the focusing point F11 of the amplifier AR1 is GO1, and the gain of the focusing point F14 is GR1. As shown in Table 2, the gain of each amplifier is optimized according to the focusing point depth, and the gain is set larger as the focusing point depth becomes deeper (GO &lt;GP &lt;GQ &lt;GR).</p><p><tables num="2"><img file="JP4832550B2_D0002.tif" /></tables></p><p> In the above, an example of changing the gain of the transmitting side amplifier or the receiving side amplifier depending on the depth of the focusing point is shown, but this effect changes the gain of both the transmitting side amplifier and the receiving side amplifier depending on the focusing point (depth). It can also be realized by letting it. That is, the gain of each amplifier of both the transmitting side amplifier and the receiving side amplifier is characterized in that the gain is optimized according to the depth of the focusing point 17, and the gain is set larger as the depth of the focusing point 17 becomes deeper. And.</p><p> FIG. 15 shows another example in which the ultrasonic flaw detector according to the embodiment of the present invention is applied to defect detection and defect sizing. As described above, in the example of FIG. 14, the defect detection and defect sizing method when the defect 22 extends in the direction directly below the sensor 14 is described.</p><p> As shown in FIG. 14, it is considered that the defect 22 extends in the downward direction in many cases, but in rare cases, the defect does not extend in the direct downward direction, but the defect or the defect tip that extends in the diagonal direction branches. It is also necessary to consider the case where there is. FIG. 15 describes an example in which an ultrasonic flaw detection test is performed without knowing the shape of the defect, which will be described in detail below. The procedure for defect detection and sizing is described below. The sensor 14 is pressed directly above the surface opening of the defect 24 that is generated in the material 21 to be inspected and extends in the diagonal direction or the tip of the defect is branched.</p><p> Since the direction of defect growth and the shape of the defect cannot be seen visually from the surface opening side, first, the focusing point of the transmitting ultrasonic wave 16 (= ultrasonic focusing receiving point) is continuously or discretely set in the direction directly below the sensor 14. After scanning and recording the ultrasonic data, the ultrasonic focusing point (= ultrasonic focusing receiving point) is then focused in the vibrating element arrangement direction (X direction in FIG. 15) of the transmitter row 15 of the sensor 14. After moving a distance of about 1/2 or 1/4 of the width (about several millimeters), the ultrasonic data is recorded by continuously or discretely scanning in the downward direction (Y direction in FIG. 15).</p><p> After that, the focusing point (= ultrasonic focusing receiving point) is further set to 1 / of the ultrasonic focusing width (about several millimeters) in the vibrating element arrangement direction (X direction in FIG. 15) of the transmitter row 15 of the sensor 14. By repeating the procedure of continuously or discretely scanning in the downward direction (Y direction in FIG. 15) and recording ultrasonic data after moving a distance of about 2 or 1/4, the lower part of the sensor 14 Two-dimensional scanning can be realized. By the scanning method and defect detection of this embodiment, it is possible to detect defects and sizing defects that are generated in the material 21 to be inspected and that extend in an oblique direction or have a branched defect tip.</p><p> FIG. 16 shows an example in which the ultrasonic flaw detector according to any of the above-described embodiments is applied to the ultrasonic flaw detection work of the shroud support portion in the reactor. The shroud support 25 and the shroud support ring 27 in the reactor are installed in the reactor pressure vessel and are welded to each other by the Inconel weld metal part 29. When the Inconel weld metal portion 29 that joins the shroud support 25 and the shroud support ring 27 is obtained by welding, a temperature rise occurs, and a heat-affected zone 28 of the shroud support ring is generated in the vicinity of the Inconel weld metal portion 29. Similarly, the heat-affected zone 26 of the shroud support is generated in the vicinity of the Inconel weld metal portion 29. It is generally considered that the Inconel weld metal part 29, the heat-affected zone 28 of the shroud support ring and the heat-affected zone 26 of the shroud support are highly sensitive to stress corrosion cracking, and defect detection and defect sizing of these parts are extremely difficult. Has become an important issue. Defect detection and defect sizing are extremely difficult to detect surface opening defects 22 by ultrasonic flaw detection methods using conventional oblique angle probes.</p><p> In addition, since the inspection of the welded part using the conventional TOFD method is an inspection with a system that straddles the weld line, the propagation path of the ultrasonic beam is the transmission probe base material weld metal part base material It is known that the ultrasonic beam bends when the ultrasonic beam enters the weld metal portion from the base metal as a receiving probe, and the ultrasonic beam is diffused / attenuated inside the weld metal. In addition, the ultrasonic flaw detection method using the conventional TOFD method requires fixing the ultrasonic transmission probe and the reception probe at regular intervals and scanning, which increases the outer dimensions. It is difficult to apply to the Inconel welded metal part 29, the heat-affected zone 28 of the shroud support ring, and the heat-affected zone 26 of the shroud support, as shown in 17. Figure 17 shows an ultrasonic flaw detector using a sensor 14 suitable for defect detection and defect sizing of the surface opening defect 22. Inconnell welded metal part 29 of the shroud support part in the reactor, the thermal influence part 28 of the shroud support ring, and It shows an example applied to the heat influence part 26 of the shroud support.</p><p> Case (1) in FIG. 16 shows an example in which an ultrasonic flaw detector using a sensor 14 suitable for defect detection and defect sizing of the surface opening defect 22 is applied to the heat-affected zone 28 of the shroud support ring. However, as can be seen from the figure, it is possible to install the sensor 14 on the top of the surface opening defect 22 (the opening of the defect 22), and the defect detection and defect applicable to the heat-affected zone 28 of the shroud support ring. Sizing is possible.</p><p> Case (3) in FIG. 16 shows an example in which an ultrasonic flaw detector using a sensor 14 suitable for defect detection and defect sizing of the surface opening defect 22 of the present invention is applied to the heat-affected zone 26 of the shroud support. However, as can be seen from the figure, it is possible to install the sensor 14 on the top of the surface opening defect 22, which enables defect detection and defect sizing applicable to the heat-affected zone 26 of the shroud support. ..</p><p> Similarly, case (2) in FIG. 16 shows an example in which an ultrasonic flaw detector using a sensor 14 suitable for defect detection and defect sizing of the surface opening defect 22 is applied to the Inconel weld metal portion 29. However, as can be seen from the figure, it is possible to install the sensor 14 on the top of the surface opening defect 22, which is applicable to the Inconel weld metal portion 29, and enables defect detection and defect sizing.</p><p> In particular, the inconel weld metal part 29 has a large ultrasonic attenuation, the ultrasonic waves are bent, and noise echoes are generated. Therefore, the conventional oblique angle search in which the ultrasonic propagation distance in the inconel weld metal part 29 is long. Defect detection and defect sizing are extremely difficult with the ultrasonic flaw detection method using a tentacle and the ultrasonic flaw detection method using the conventional TOFD method. On the other hand, in the ultrasonic flaw detection method using the transmission / reception integrated small array sensor 14 of the present invention, the transmission / reception integrated small array sensor 14 is installed on the Inconel weld metal portion 29 to perform defect detection and defect sizing. , Has the following advantages. (1) The ultrasonic propagation distance of the weld metal part can be made relatively short, and the detection efficiency of the diffracted wave becomes high. (2) Even if there is some influence of the bending of the ultrasonic wave, the ultrasonic wave emitted from the transmission / reception integrated small array sensor 14 and the diffracted wave from the defect tip propagate in almost the same path, so that the transmission / reception integrated small array Since the sensor 14 is small and the transmitting ultrasonic vibrator group and the receiving ultrasonic vibrator group are close to each other, the diffracted wave can be detected efficiently. Further, in the transmission / reception integrated compact array sensor in which the transmitting ultrasonic vibrator and the receiving ultrasonic vibrator are alternately arranged, which will be described later in another embodiment, the ultrasonic transmission region and the reception region may be substantially the same region. Therefore, it is possible to prevent a decrease in the detection efficiency of the diffracted wave due to the influence of the bending of the ultrasonic wave, and it is possible to efficiently detect the diffracted wave and dramatically improve the defect detection efficiency. (3) Since it is a direct contact, there is no influence of the shape echo reflected from the inspection target part, which is a problem in the water immersion method, and the SN ratio of the diffracted wave becomes high. That is, as compared with the conventional method, the present invention has significantly improved defect detection and defect sizing properties.</p><p> The defect sizing method will be described with reference to FIG. Using a part with a known plate thickness t like the shroud support 25 in FIG. 16, the ultrasonic waves emitted by the sensor 14 are reflected back to the bottom surface, which is the opposite surface, and the sound velocity of the material is increased from the detected time. It is possible to evaluate, and defect sizing is possible from the relationship between the speed of sound and the time when the diffracted wave appears. Similarly, the inconel weld metal portion 29 in FIG. 16 also uses a portion having a known plate thickness t, and the ultrasonic waves emitted by the sensor 14 are reflected back to the bottom surface, which is the opposite surface, and the detected time. It is possible to evaluate the sound velocity of the material more, and defect sizing is possible from the relationship between the sound velocity and the time when the diffracted wave appears.</p><p> The size of the sensor 14 is smaller than or equal to the width of the inspection target portion or the weld metal portion which is the inspection target portion. That is, Wwel in FIG. 16 is the width of the inspection target portion or the weld metal portion which is the inspection target portion, and W is the size (width) of the sensor 14. As can be seen from FIG. 16, the size (width) W of the sensor 14 is smaller than or equivalent to the width Wwel of the weld metal portion to be inspected or the inspection target portion. Therefore, for example, the weld metal to be inspected. When the defect 22 is detected by the ultrasonic wave transmitted from the sensor 14 in the portion, it is not necessary to pass through the metal structure outside the other weld metal. FIG. 16 shows the case where there are steps at both ends of the weld, but the same applies to the X groove, V groove, and check groove of welding on a surface without steps, and the size (width) W of the sensor 14 is It is preferable that the width of the weld metal portion to be inspected or the weld metal portion to be inspected is smaller than or equal to the width Wwel.</p><p> FIG. 17 shows an example in which the ultrasonic flaw detector according to any of the above-described embodiments is applied to flaw detection in the vicinity of the CRD housing stub tube 31 and the nuclear pressure vessel 32 at the bottom of the reactor. The inspection device 34 capable of accommodating the sensor 14 and the articulated manipulator 33 of the ultrasonic flaw detector according to any of the embodiments described is supported by the CRD housing 35 and restrained by the core support plate 36. The signal cable of the sensor 14, the signal cable of the articulated manipulator 33, the power cable, the high-pressure water hose, etc. are bundled together as a cable and hose 37 from the upper part of the inspection device 34 to the operation floor, which is the operation / control place of the upper part. It is stretched and connected to each control device.</p><p> The manipulator base 38 is fixed to the manipulator base up and down and the rotation mechanism 39, and the manipulator base has a structure capable of up and down movement and rotational movement. The manipulator 33 is composed of three flexion joints 40 and two rotary joints 41. There is a hand 42 at the tip of the manipulator 33, and the grip portion 43 attached to the small array sensor 14 is gripped by the hand 42. Between the small array sensor 14 and the grip portion 43, the small array sensor 14 has a structure capable of following curved surfaces such as the welded portion between the CRD housing stub tube 31 and the nuclear pressure vessel 32 and the CRD housing stub tube 31 and the nuclear pressure vessel 32. The compliance mechanism 44 with is installed. This compliance mechanism 44 can be changed on all three axes of X-axis, Y-axis, and Z-axis. The compliance mechanism 44 makes it possible for the small array sensor 14 to smoothly follow curved surfaces such as the welded portion between the CRD housing stub tube 31 and the nuclear pressure vessel 32 and the CRD housing stub tube 31 and the nuclear pressure vessel 32. As a result, defect detection and defect sizing of defect 22 can be realized by using the defect detection and defect sizing method described above.</p><p> FIG. 18 shows an example in which the sensor 14 of the ultrasonic flaw detection device according to any of the above-described embodiments is mounted on the suspension type inspection device 45, that is, the underwater inspection device. The hanging inspection device 45 is equipped with a sensor 14, two underwater CCD cameras 46, an illumination 47, a thruster 48, and a clad removal and recovery device 49.</p><p> The suspended inspection device 45 detects defects and performs defect sizing by visual tests and ultrasonic tests, which are non-destructive tests, to check for defects generated in general industrial tanks and pools and in-reactor structures in nuclear reactors. It is the purpose. Since the suspension type inspection device 45 is suspended by the suspension wire 50, the suspension type inspection device 45 is inspected by a human being operating the suspension wire 50 from the air above and using the propulsive force of the thruster 48. It is possible to guide the device 45 to the inspection target portion and bring the sensor 14 into close contact with the inspection target portion, and by using the sensor 14, defect detection and defect sizing are possible.</p><p> The two underwater CCD cameras 46 are for visual testing, and the two underwater CCD cameras 46 can be used to reproduce stereo images, enabling the inspector to accurately recognize the unevenness of the inspection site. It is possible to easily determine whether the defect is an unevenness or a defect (surface opening defect), the visibility is high, and the visual inspection can be efficiently performed. The illumination 47 is used as a light source for the underwater CCD camera 46 when the inspection site is dark. The light bulb is composed of a halogen lamp, the metal is a ride lamp, a light emitting diode, etc., and the visibility of the underwater CCD camera 46 is improved. Therefore, it is equipped with a dimming function.</p><p> The thruster 48 is a propulsion device that controls the posture of the suspension type inspection device 45. It is possible to control the rotation direction and rotation speed of the thruster 48 to change the posture of the suspension type inspection device 45. The clad removing / recovering device 49 is a device for removing and sucking deposits such as clad adhering to the inspection site. The clad removing and collecting device 49 is composed of a rotating brush for removing deposits and a device for collecting the peeled deposits. By removing deposits such as clad using the clad removing and recovering device 49, it becomes possible to find defects (surface opening defects) under the deposits such as clad.</p><p> Further, the removed deposits such as clad are sucked by using the clad recovery hose 110 and the suction device, and the structure is such that the deposits such as clad are recovered by the filter. Therefore, since water does not become turbid, it is possible to efficiently carry out a visual inspection. Defect detection and defect sizing by applying this suspended inspection device 45 to visual tests and ultrasonic tests of defects generated in general industrial tanks and pools and internal structures in nuclear reactors. Can be realized. Further, by making the suspension type inspection device 45 a remote control capable of self-propelled swimming, its mobility is enhanced and the inspection range is expanded. That is, the underwater inspection device equipped with the sensor 14 and two underwater CCD cameras 46, lighting 47, thruster 48 and clad removal and recovery device 49 can be self-propelled and can be remotely controlled. Is also good. In that case, the structure shown in FIG. 20 can be adopted as the basic structure of the underwater inspection device.</p><p> In the ultrasonic flaw detectors of each of the embodiments described below, the ultrasonic transmission / reception surface (also referred to as the entrance / exit surface of ultrasonic waves) facing the inspection target of the sensor 14 is flat, but it depends on the shape of the surface of the inspection target. Does not have to be flat as described below. That is, an example in which the ultrasonic wave transmitting / receiving surface has a shape other than flat is described below. FIG. 19 shows an example of the shape of the ultrasonic wave transmitting / receiving surface of the sensor 14 when the inspection target portion 53 has a concave shape. When the inspection target part 53 has a concave shape and the contact surface of the sensor 14 with the inspection target part 53 is a flat plate, a gap is created between the contact surface of the sensor 14 and the surface of the inspection target part 53, and the inspection target. The efficiency of ultrasonic wave incident on the site 53 may decrease.</p><p> In order to prevent such a decrease in ultrasonic incident efficiency, a cushioning material 52 such as acrylic or polyethylene having a cylindrical shape or a partial surface shape of a spherical shape is attached to the ultrasonic input / output surface of the sensor 14. By matching the cushioning material 52 to the shape of the inspection target portion 53, it is possible to prevent a decrease in ultrasonic incident efficiency. As for the shape of the cushioning material 52, the radius of the shape of the cushioning material 52 is smaller than the radius of the concave shape of the inspection target portion 53. As a result, the followability of the cushioning material 52 to the inspection target portion 53 is improved, the decrease in ultrasonic incident efficiency can be prevented, and highly reliable and highly accurate ultrasonic inspection can be realized.</p><p> FIG. 20 also shows an example of the sensor 14 used when the inspection target portion 53 has a concave shape. The difference from FIG. 19 is that the arrangement of the vibrating elements of the transmitting oscillator row 15 and the receiving oscillator row 19 is arranged so as to follow the shape of the inspection target portion 53. As a result, as in FIG. 19, it is possible to prevent a decrease in ultrasonic incident efficiency, and it is possible to realize highly reliable and highly accurate ultrasonic inspection.</p><p> FIG. 21 shows an example of the sensor 14 corresponding to the case where the inspection target portion 53 has a convex diameter shape. When the inspection target part 53 has a convex diameter shape and the contact surface of the sensor 14 with the inspection target part 53 is a flat plate, a gap is created between the contact surface of the sensor 14 and the inspection target part 53, and the inspection target part 53 is reached. Ultrasonic incident efficiency may decrease. In order to prevent such a decrease in ultrasonic incident efficiency, a cushioning material 52 such as acrylic or polyethylene having a cylindrical shape or a partial surface shape of a spherical shape is attached to the ultrasonic input / output surface of the sensor 14. .. By matching the cushioning material 52 to the shape of the inspection target portion 53, it is possible to prevent a decrease in ultrasonic incident efficiency. As for the shape of the cushioning material 52, the radius of the shape of the cushioning material 52 is larger than the radius of the convex diameter shape of the inspection target portion 53. As a result, the followability of the cushioning material 52 to the inspection target portion 53 is improved, the decrease in ultrasonic incident efficiency can be prevented, and highly reliable and highly accurate ultrasonic inspection can be realized.</p><p> FIG. 22 also shows an example of the sensor 14 when the inspection target portion 53 has a convex diameter shape. The difference from FIG. 21 is that the vibrating element arrangements of the transmitting oscillator row 15 and the receiving oscillator row 19 are arranged in a bow shape according to the shape of the inspection target portion 53. As a result, it is possible to prevent a decrease in ultrasonic incident efficiency as in FIG. 21, and it is possible to realize highly reliable and highly accurate ultrasonic inspection.</p><p> FIG. 23 shows a mechanism for improving the followability of the sensor 14 to the inspection target portion 53 to the sensor 14 of the ultrasonic flaw detector according to the above-described embodiment. When an inspection is performed while scanning the uneven inspection target portion 53 with the sensor 14, the end portion of the sensor 14 interferes with the inspection target portion 53, and smooth scanning of the sensor 14 and accurate adhesion to the inspection target portion 53 are obtained. It may not be possible.</p><p> In order to avoid this phenomenon, a sliding mechanism 54 such as a roller or a ball bearing is attached to the end of the sensor 14 as a friction reducing means to prevent the end of the sensor 14 from interfering with or colliding with the inspection target portion 53. As a result, smooth scanning of the sensor 14 and accurate adhesion to the inspection target portion 53 can be obtained, and highly reliable and highly accurate ultrasonic inspection can be realized.</p><p> FIG. 24 shows an example in which the sensor 55 is made by devising the arrangement of each vibrating element between the transmitting oscillator row and the receiving oscillator row of the sensor 14 of the ultrasonic flaw detector according to the embodiment described. In the example of FIG. 24, the device configuration and the control system are the same as those of FIG. The points to be devised are as follows. That is, in FIG. 24, the sensor 55 is configured by alternately arranging the vibrating elements of the transmitting oscillator 15 and the vibrating elements of the receiving oscillator 19. The advantage of the sensor 55 is the ultrasonic waves and defect tips emitted from another small array sensor 55 with integrated transmission and reception, even if there is some influence of bending when the ultrasonic waves propagate through the weld metal part or non-uniform material. Since the diffracted wave 18 from the above propagates in the same path, the ultrasonic transmission region and the reception region can be made exactly the same region, and it is possible to prevent a decrease in the detection efficiency of the diffracted wave due to the influence of ultrasonic bending, and diffraction. It is possible to efficiently detect waves and dramatically improve defect detection efficiency.</p><p> Figure 25 shows an in-reactor inspection device using an ultrasonic flaw detector according to the example described. That is, an embodiment in which the sensor 14 or 55 of the ultrasonic flaw detector according to the above-described embodiment is attached to the lower tip of the rod-shaped operation pole 133 and the defect depth sizing in the reactor is performed is shown. The following shows an example in which the sensor 14 is used as a representative. The sensor 14 is attached to the lower tip of the operation pole 133. The lower part of the operation pole 133 is lowered from the work carriage 115 on the operation floor 118 into the reactor water 119 in the pressure vessel of the reactor. The alignment of the sensor 14 with the defect 22 is monitored by the illuminated camera 135 injected into the reactor water 119 in the reactor pressure vessel almost at the same time as the operation pole 133 with the sensor 14, while monitoring the reactor pressure vessel. Align the sensor 14 directly above the defect 22 (opening of the defect 22) of the internal structure 131 such as the shroud inside. The camera cable 134 of the illuminated camera 135 is connected to the monitor on the work trolley 115, and the position of the sensor 14 on the work trolley 115 can be monitored by the monitor.</p><p> After aligning the sensor 14 directly above the defect 22 (the opening of the defect 22), the ultrasonic flaw detector main body 122 connected to the sensor 14 by the signal cable 123 enables the detection and depth sizing of the defect 22. .. In order to bring the sensor 14 into close contact with the surface of the defect 22 (internal structure 131), a familiar mechanism 136 (compliance mechanism, gimbal mechanism) is installed between the operation pole 133 and the sensor 14. Further, by installing an XY scanner between the operation pole 133 and the transmission / reception integrated small array sensor 14, the defect distribution can be measured.</p><p> In FIG. 26, another inspection device in the reactor using the ultrasonic flaw detector according to the above-described embodiment will be described below. An inspection / repair device 114 (hereinafter referred to as a mast 114) is suspended from the work trolley 115 on the operation floor 118 into the reactor water 119 in the pressure vessel of the reactor by a wire 117 from the vertical movement mechanism 116 on the work trolley 115. To be taken down. The mast 114 lowered into the reactor water 119 is seated on the core support plate 121 in the pressure vessel of the reactor and supported by the upper lattice plate 120 in the pressure vessel of the reactor. A pantograph mechanism 113, which is a stretchable link mechanism, is installed on the mast 114, and an inspection head 111 including a sensor 14 is attached to the tip of the pantograph mechanism 113. Therefore, when the pantograph mechanism 113 is extended, the pantograph mechanism 113 contracts and the inspection head 111 including the sensor 14 housed in the mast 114 protrudes in the horizontal direction. In this way, the sensor 14 can move forward and backward from the mast 114 by the expansion and contraction action of the pantograph mechanism 113.</p><p> Defect detection or defect depth sizing is performed by pressing the sensor 14 against the in-core structure 131 in the reactor by the extension action of the pantograph mechanism 113. The sensor 14 is housed inside the inspection head 111, and presses the sensor 14 against the in-core structure 131 such as the shroud to be inspected to detect and sizing defects such as the shroud. The sensor 14 is held by a gimbal mechanism installed inside the inspection head 111, the gimbal mechanism is held by a pressing mechanism, and the pressing mechanism is gripped by an XY scanner. That is, an XY scanner, a pressing mechanism, a gimbal mechanism, and a small array sensor 14 with integrated transmission / reception are built in the inspection head 111. The pantograph mechanism 113 is supported by a linear movement mechanism inside the mast 114, and the linear movement mechanism allows the pantograph mechanism 113 to move up and down inside the mast 114.</p><p> As a result, when performing detailed flaw detection of the shroud or the like, which is the surface to be inspected, or when it is desired to move the measurement point slightly, the sensor 14 is moved using the XY scanner. Further, when the rough flaw detection or the inspection location is significantly changed, the inspection head 111 and the sensor 14 can be moved by the linear movement mechanism and the pantograph mechanism 113 inside the mast 114.</p><p> Next, a method of charging and recovering the mast 114 into the pressure vessel of the reactor will be described. The mast 114 is a vertical movement mechanism 116 installed on the work trolley 115, and is suspended from the height of the operation floor 118 into the furnace water 119 by using a wire 117 and lowered. The inspection / repair device 114 passes through the upper grid plate 120 and is seated on the core support plate 121. After that, according to the procedure described above, the inspection head 111 is expanded in the inspection position direction by expanding and contracting the pantograph mechanism 113, and the sensor 14 is pressed against the shroud or the like which is the inspection target surface to detect and size defects such as the shroud. .. After the inspection is completed, the inspection head 111 is stored in the 114 by reversing the procedure of deploying the inspection head 111, and the inspection / repair device 114 is lifted to the height of the operation floor 118 by the vertical movement mechanism 116 installed on the work trolley 115. Then, it is collected on the operation floor 118 using an overhead crane or the like.</p><p> Operations such as rotation of the mast 114, vertical movement of the pantograph mechanism 113, and deployment / storage are controlled by the inspection / repair device controller 124 on the operation floor 118, and the control signal is transmitted using the signal cable 123. The sensor 14 built in the inspection head 111 is controlled by the ultrasonic flaw detector main body 122, and the signals are transmitted to each other using the signal cable 123.</p>

The present invention is used in an ultrasonic flaw detector for non-destructively detecting defects generated in a structure such as a weld line of a welded structure and cracks generated in the vicinity thereof by using ultrasonic waves.

1 ... Input device, 2 ... Memory, 3 ... Ultrasonic control device, 4 ... Information processing device, 5 ... I / O, 6 ... Display device, 7 ... Transmission Ultrasonic transducer control device, 8 ... reception signal processing device, 9 ... transmission side amplifier control device, 10 ... reception side amplifier control device, 11 ... transmission side amplifier, 12 ... reception side Amplifier, 13 ... signal cable, 14 ... small array sensor with integrated transmission / reception, 15 ... transmission oscillator sequence, 16 ... ultrasonic waves, 17 ... focusing point, 18 ... diffracted wave, 19. .. Receiver row, 20 ... Ultrasonic received signal (electrical signal), 21 ... Material to be inspected, 22 ... Defect.