JP6826949B2 - Ultrasonography system - Google Patents

Description

The present invention targets a cylindrical weld having a weld interface that is inclined with respect to the thickness direction perpendicular to the surface of the subject, which has a side shape of a cone or a truncated cone, and the inside formed along the weld interface. It relates to an ultrasonic inspection system for detecting defects.

Maintenance of component equipment in a power plant is necessary to maintain normal operation, and the role played by non-destructive inspection technology is very important. Especially in nuclear power plants, it is important to ensure the soundness of primary reactor equipment such as reactor pressure vessels (RPV) and recirculation piping, and ultrasonic flaw detection tests (ultrasonic flaw detection tests) are used as volume inspections for welds where defects are likely to occur. UT) is carried out to detect defects and evaluate their size.

One example of the inspection target is the welded part of the lower mirror part of the reactor pressure vessel. As shown in FIGS. 1 and 2, the lower mirror portion of the reactor pressure vessel has a spherical crown-shaped dome portion 11 and a conical band-shaped (in other words, the lateral shape of the truncated cone) lower mirror petal portion 12. They are joined by a cylindrical welded portion 13. A plurality of control rod drive mechanism housings (CRD housings) 14 are formed in the dome portion 11, and a plurality of internal pump casings (RIP casings) 15 are formed in the mirror petal portion 12.

Generally, in pre-service inspection and in-service inspection, ultrasonic inspection by a single probe method is performed in order to detect defects (cracks) opened on the inner surface side of the speculum (for example, Patent Documents). 1). Specifically, for example, as shown in FIG. 3, transmission / reception is performed to the outer surface side (lower side in FIG. 3) of the mirror petal portion 12 so as to avoid an interference portion including the RIP casing 15 and the R portion 15a around the RIP casing 15. A casing probe 20 for transmission and reception is arranged, and ultrasonic waves are transmitted from the casing probe 20 for transmission and reception toward the vicinity of the opening of the defect 16 (crack). Then, the ultrasonic wave (corner echo) reflected at the corner formed by the defect 16 and the inner surface of the mirror petal portion 12 is received by the transmission / reception oblique angle probe 20. As a result, the defect 16 opened on the inner surface side (upper side in FIG. 3) of the lower mirror portion is detected.

Japanese Unexamined Patent Publication No. 6-11595

On the other hand, in order to detect planar internal defects (specifically, cracks and poor penetration inherent in the welded portion 13) that occur along the weld boundary surface of the welded portion 13 in the final stage of manufacturing inspection, the mirror mirror. It may be necessary to inspect the weld 13 over the entire depth direction of the portion.

Here, in the vertical cross section shown in FIG. 4, the welding boundary surface 13a on the outer peripheral side (right side in FIG. 4) of the welded portion 13 is inclined with respect to the thickness direction perpendicular to the surface of the mirror petal portion 12. From the transmission / reception oblique angle probe so that ultrasonic waves are incident on the welding boundary surface 13a in the normal direction (that is, in the direction perpendicular to the internal defect 17 generated along the welding boundary surface 13a). It is possible to set 20 transmission / reception refraction angles. As a result, it is possible to transmit ultrasonic waves from the transmission / reception oblique angle probe 20 to the internal defect 17, and to receive the ultrasonic waves reflected by the internal defect 17 by the transmission / reception oblique angle probe 20. Further, it is possible to increase the amplitude of the ultrasonic wave reflected by the internal defect 17, that is, the amplitude of the ultrasonic wave received by the transmission / reception oblique angle probe 20, and detect the internal defect 17 with high sensitivity.

However, the closer the scanning point of the welding boundary surface 13a (that is, the point at which the internal defect 17 is detected) is to the inner surface of the lower mirror portion, the farther the transmission / reception oblique angle probe 20 is from the welding boundary surface 13a (that is, the point where the internal defect 17 is detected). (See the virtual arrangement shown by the alternate long and short dash line in FIG. 4), the interference portion of the transmission / reception oblique angle probe 20 and the RIP casing 15 and the like interfere with each other. Therefore, in the one-probe method using the transmission / reception oblique angle probe 20, it is difficult to detect the internal defect 17 in the depth range U shown in FIG. 4, for example.

An object of the present invention is to provide an ultrasonic inspection system capable of detecting internal defects with high sensitivity while avoiding interference between an oblique angle probe and an interfering portion of a subject.

In order to achieve the above object, the present invention targets a cylindrical welded portion having a weld interface inclined in a thickness direction perpendicular to the surface of a subject having a side shape of a cone or a cone base. An ultrasonic inspection system that detects internal defects that occur along the welding interface by using a transmission oblique angle probe and a receiving oblique angle probe arranged on the surface of the subject. Corresponding to the scanning point of the welding interface to be moved in the depth direction of the subject, the virtual plane including the scanning point of the welding interface and the normal vector of the welding interface on the scanning point and the subject. The transmitting point of the transmitting oblique angle probe and the receiving point of the receiving oblique angle probe are located on the intersection line intersecting with the surface of the above, and the transmitting oblique angle probe and the said. A probe moving device for arranging the transmitting oblique probe and the receiving oblique probe so as to avoid interference between the receiving oblique probe and the interfering portion of the subject is provided. The probe moving device is movable along the circumferential direction of the welded portion, and is around the normal axis of the surface of the subject with respect to the bus direction of the surface of the subject at the moving position in the circumferential direction. In the circumferential direction of the welded portion with the first drive device that moves the transmission oblique angle probe along the one bus direction while fixing the swing angle of the transmitting oblique angle probe. The swing angle of the receiving oblique angle probe around the normal axis of the surface of the subject is fixed with respect to the other bus direction of the surface of the subject at the movement position in the circumferential direction. While having a second drive device for moving the receiving oblique probe along the other bus direction, the transmitting oblique probe is in the transmission path in the virtual plane. The transmission refraction angle and the swing angle are set so as to transmit ultrasonic waves and avoid interference with the interference portion of the subject, and the receiving oblique angle probe is the virtual one. The reception refraction angle and the swing angle are set so as to receive ultrasonic waves through a reception path in a plane and to avoid interference with the interference portion of the subject.

According to the present invention, internal defects can be detected with high sensitivity while avoiding interference between the oblique angle probe and the interference portion of the subject.

It is a bottom view of the lower mirror part of the reactor pressure vessel which is an example of a subject. FIG. 1 is a vertical sectional view of the lower mirror portion according to the middle sectional section II-II. It is a vertical cross-sectional view of the lower mirror part for demonstrating one probe method which detects a defect opened on the inner surface side of the lower mirror part of a reactor pressure vessel. It is a vertical sectional view of the lower mirror part for demonstrating one probe method for detecting an internal defect generated in the welded part of the lower mirror part of a reactor pressure vessel. It is a bottom view of the lower mirror part which shows the arrangement of the oblique angle probe for transmission and the oblique angle probe for reception in one embodiment of the present invention. FIG. 5 is a diagram showing a transmission oblique angle probe, a receiving oblique angle probe, and an ultrasonic transmission path and a reception path projected onto a vertical cross section of the lower mirror portion according to the middle cross section VI-VI. It is a block diagram which shows the structure of the ultrasonic inspection system in one Embodiment of this invention. It is a bottom view of the lower mirror part which shows the structure of the probe moving device in the comparative example. FIG. 8 is a vertical sectional view of the lower mirror portion according to the middle sectional section IX-IX. It is a bottom view of the lower mirror part which shows the structure of the probe moving device in one Embodiment of this invention, and shows the case where the scanning point of a welding boundary surface is relatively deep. FIG. 10 is a vertical sectional view of the lower mirror portion according to the middle sectional section XI-XI. It is a bottom view of the lower mirror part which shows the structure of the probe moving device in one Embodiment of this invention, and shows the case where the scanning point of a welding boundary surface is relatively shallow. FIG. 12 is a vertical cross-sectional view of the lower mirror portion according to the middle cross section XIII-XIII. It is a vertical cross-sectional view in the generatrix direction of the outer surface of the mirror petal portion corresponding to the position of the transmission point of the transmission oblique angle probe, and is the swing angle and the apparent transmission refraction angle of the transmission oblique angle probe. It is a figure for demonstrating the relationship. It is a figure which shows the specific example of the relationship between the swing angle of a transmission oblique angle probe, and the deviation angle of a transmission direction vector with respect to a horizontal plane. It is a figure which shows the positional relationship of the transmission point of the transmission oblique angle probe, the receiving point of the receiving oblique angle probe, the central axis of the RIP casing, and the central axis of the lower mirror portion on the horizontal plane. It is a figure which shows the specific example of the distance between the central axis of a RIP casing, and the transmission point of a transmission oblique angle probe, which changes according to the depth of the scanning point of a welding boundary surface.

As an inspection target of the present invention, taking the welded portion 13 of the lower mirror portion of the reactor pressure vessel as an example, a super-surface-like internal defect 17 generated along the weld boundary surface 13a on the outer peripheral side of the welded portion 13 is detected. The ultrasonic inspection method will be described. The same parts as those described with reference to FIGS. 1 to 4 are designated by the same reference numerals, and the description thereof will be omitted as appropriate.

In the one-probe method using the transmission / reception oblique angle probe 20, it is difficult to detect the internal defect 17 in the depth range U shown in FIG. 4, for example. Therefore, the present invention implements a two-probe method using a transmission oblique angle probe and a receiving oblique angle probe.

FIG. 5 is a bottom view of the lower mirror portion showing the arrangement of the transmission oblique angle probe and the receiving oblique angle probe according to the embodiment of the present invention, and is a view seen from the arrow V direction in FIG. Equivalent to. FIG. 6 shows the transmission oblique angle probe, the receiving oblique angle probe, and the ultrasonic transmission path and reception path projected horizontally on the vertical cross section of the lower mirror portion according to the middle cross section VI-VI of FIG. It is a figure which shows.

The transmission oblique angle probe 21 and the receiving oblique angle probe 22 avoid an interference portion composed of the RIP casing 15 and its peripheral R portion 15a on the outer surface (surface) 12a of the mirror petal portion 12. As shown above, they are arranged in a V shape with the interference part in between. To be described in detail, the scanning point D of the welding boundary surface 13a is moved in the depth direction of the lower mirror portion, and the scanning point D of the welding boundary surface 13a and the scanning point D thereof correspond to the scanning point D of the welding boundary surface 13a. An intersection line E (this) where the virtual plane C (horizontal plane in this embodiment; see FIG. 14 described later) including the normal vector of the welding boundary surface 13a on the scanning point D and the outer surface 12a of the mirror petal portion 12 intersect. in embodiments, circular) as receiving point P ₂ of the transmission point P ₁ and the receiving angle probe 22 for transmitting the angle probe 21 is positioned over, and transmitting the angle probe The transmission oblique angle probe 21 and the receiving oblique angle probe 22 are arranged so as to avoid interference between the 21 and the receiving oblique angle probe 22 and the interfering portion of the mirror petal portion 12.

Also, to transmit ultrasound at the transmission path S ₁ in the virtual plane C, and, to avoid interference with the interference portion of the transmission angle probe 21 and the lower mirror petal section 12, feed The transmission refraction angle θ _{1 and the} like of the credit oblique angle probe 21 are set (details will be described later). Further, to avoid interference at the receiving path S ₂ in the virtual plane C to receive ultrasound, and an interference portion of the receiving angle probe 22 and the lower mirror petal section 12, reception The reception refraction angle θ _{2 and the} like of the oblique angle probe 22 are set (details will be described later).

As a result, the ultrasonic waves propagate in the virtual plane C perpendicular to the internal defect 17 generated along the welding boundary surface 13a, and the amplitude of the ultrasonic wave reflected by the internal defect 17, that is, the reception oblique. The amplitude of the ultrasonic waves received by the angle probe 22 can be increased. Therefore, the internal defect 17 can be detected with high sensitivity. Further, it is possible to avoid the interference between the oblique angle probes 21 and 22 and the interference portion of the lower mirror petal portion 12.

Here, an angle of opening angle γ between the transmit path S ₁ and the receiving path S ₂ in the virtual plane C (see Fig. 5). Further, the transmission around the normal axis of the outer surface 12a of the lower mirror petals 12 in the transmission point P ₁ of the angle probe 21, probe 21 probe transmission bevel and the generatrix direction of the outer surface 12a of the lower mirror petals 12 Let the angle between the directions be the swing angle σ ₁ (see FIG. 14 described later). Similarly, about the normal axis of the outer surface 12a of the lower mirror petals 12 at the reception point P ₂ of the reception angle probe 22, ultrasonic probe receiving oblique with generatrix direction of the outer surface 12a of the lower mirror petals 12 Let the angle between the directions of 22 be the swing angle σ ₂ .

Further, by projecting the generatrix direction of the outer surface 12a of the lower mirror petal portion 12 corresponding to the transmission point P ₁ of the transmission angle probe 21 to the virtual plane C, between the transmit path S ₁ and the projected generatrix direction The apparent swing angle is ρ ₁ (see FIGS. 10 and 16 described later). Similarly, by projecting the generatrix direction of the outer surface 12a of the lower mirror petal portion 12 corresponding to the received point P ₂ of the reception angle probe 22 to the virtual plane C, between this projected generatrix direction of the receive path S ₂ Let the apparent swing angle ρ ₂ be (see FIG. 10 described later). If the conditions such as the tilt angle β of the outer surface 12a of the lower mirror petal portion 12 are the same, the swing angle σ _{1 of} the transmission tilt angle probe 21 and the apparent swing angle ρ ₁ have a one-to-one relationship. , The swing angle σ _{2 of} the receiving oblique probe 22 and the apparent swing angle ρ ₂ have a one-to-one relationship.

An ultrasonic inspection system for carrying out the above-mentioned ultrasonic inspection method will be described. FIG. 7 is a block diagram showing a configuration of an ultrasonic inspection system according to an embodiment of the present invention.

The ultrasonic inspection system of the present embodiment includes the transmission oblique angle probe 21 and the receiving oblique angle probe 22 described above, and the transmitting oblique angle probe 21 along the outer surface 12a of the mirror petal portion 12. A probe moving device 23 for moving the receiving oblique probe 22 and a transmitting / receiving device 24 for controlling the transmission / reception of ultrasonic waves by the transmitting oblique probe 21 and the receiving oblique probe 22. A control device 25 that controls a probe moving device 23 and a transmitting / receiving device 24, a computing device 26 that executes various arithmetic processes, a storage device 27 that records various data, and a display device that displays various information on a screen. The 28 and an input device 29 for inputting various conditions and executing various operations are provided. The calculation device 26 is composed of a board or the like on which a computer or an electronic component is mounted, and the storage device 27 is composed of a hard disk, a random access memory (RAM), or the like. The display device 28 is composed of a display or the like, and the input device 29 is composed of a mouse, a keyboard, a touch panel, buttons, or the like.

The control device 25 outputs a command related to the circumferential position and depth of the scanning point D to the probe moving device 23. In response to a command from the control device 25, the probe moving device 23 includes a virtual plane C including a scanning point D of the welding boundary surface 13a and a normal vector of the welding boundary surface 13a on the scanning point D, and a mirror petal. parts as 12 and the outer surface 12a of the position is received point P ₂ of the transmission point P ₁ and the receiving angle probe 22 for transmitting the angle probe 21 on the line of intersection E intersecting and feeding The transmission oblique probe 21 and the receiving oblique probe 21 and the receiving oblique probe 21 so as to avoid interference between the credit oblique probe 21 and the receiving oblique probe 22 and the interfering portion of the mirror petal portion 12. 22 is arranged.

The transmission / reception device 24 acquires a flaw detection result including waveform data of ultrasonic waves received by the transmission oblique angle probe 21. The storage device 27 stores the flaw detection result acquired by the transmission / reception device 24 in association with the circumferential position and depth of the scanning point D of the welding boundary surface 13a. The display device 28 displays the flaw detection result acquired by the transmission / reception device 24 or the flaw detection result stored by the storage device 27 in association with the circumferential position and depth of the scanning point D of the welding boundary surface 13a.

The structure and action / effect of the probe moving device 23 of the present embodiment will be described in comparison with a comparative example.

FIG. 8 is a bottom view of the lower mirror portion showing the structure of the probe moving device in the comparative example. FIG. 9 is a vertical cross-sectional view of the lower mirror portion according to the cross section IX-IX in FIG.

The probe moving device 50 of the comparative example is from the viewpoint of keeping the above-mentioned opening angle γ (see FIG. 5) constant when the scanning point D of the welding boundary surface 13a is moved in the depth direction of the lower mirror portion. moves the transmission angle probe 21 along the transmit path S _1, and is configured to move the receiving angle probe 22 along a receive path S _2.

Specifically, the probe moving device 50 includes an annular track rail 51 extending along the circumferential direction of the welded portion 13, a moving body 52 capable of traveling on the track rail 51, and a moving body 52. a fixed arm 53A extending along the transmission path S ₁ from and movable along the fixed arm 53A, a probe support device 54A for supporting the transmission angle probe 21, received from the mobile 52 a fixed arm 53B extending along the path S _2, and movable along the fixed arm 53B, and a probe support device 54B for supporting a receiving angle probe 22. Then, the position of the moving body 52 in the extending direction of the track rail 51 is controlled in response to a command relating to the circumferential position of the scanning point D. Further, in response to a command relating to the depth of the scanning point D, the position of the probe support device 54A (and thus the position of the transmission oblique angle probe 21) in the extending direction of the fixed arm 53A is controlled, and the position is controlled. The position of the probe support device 54B (and thus the position of the receiving oblique angle probe 22) in the extending direction of the fixed arm 53B is controlled.

As shown in FIG. 9, if the starting point on the outer surface 12a of the mirror petal portion 12 that projects the scanning point D in the vertical direction is F, the fixed arm 53A is at the starting point F of the outer surface 12a of the mirror petal portion 12. It extends so as to be parallel to the tangent plane G. Then, since the contour of the outer surface 12a of the mirror petal portion 12 in the extending direction of the fixed arm 53A is curved, the fixed arm is adjusted according to the position of the transmission oblique angle probe 21 in the extending direction of the fixed arm 53A. The distance between the 53A and the outer surface 12a of the mirror petal portion 12 changes. Therefore, the probe support device 54A requires a pressing mechanism 55 that presses the transmission oblique angle probe 21 against the outer surface 12a of the mirror petal portion 12. Further, according to the position of the transmitting angle probe 21 in the extending direction of the fixed arm 53A, the normal direction H _a of the normal direction is changed (for example, in FIG. 9 of the outer surface 12a of the lower mirror petals 12 , _Hb ). That is, (see angle J _a, J _b of example in FIG. 9) which angle is changed between the normal direction of the outer surface 12a of the direction I perpendicular to the extending direction of the fixed arm 53A lower mirror petal section 12. Therefore, from the viewpoint of the contact between the transmission oblique angle probe 21 and the outer surface 12a of the lower mirror petal portion 12, the gimbal that causes the posture of the transmission oblique angle probe 21 to follow the outer surface 12a of the lower mirror petal portion 12. A mechanism 56 is required.

For the same reason, the probe support device 54B lowers the posture of the pressing mechanism 55 that presses the receiving oblique probe 22 against the outer surface 12a of the mirror petal portion 12 and the receiving oblique probe 22. A gimbal mechanism 56 that follows the outer surface 12a of the mirror petal portion 12 is required. Therefore, the probe moving device 50 of the comparative example becomes complicated and large.

Further, due to the presence of the gimbal mechanism 56, the posture of the transmitting oblique angle probe 21 and the attitude of the receiving oblique angle probe 22 change, so that the transmitting direction and the receiving oblique angle probe 21 of the transmitting oblique angle probe 21 change. The receiving direction of the angle probe 22 may change, and the detection sensitivity may decrease. Therefore, as the transmission oblique angle probe 21 and the receiving oblique angle probe 22, an array probe having a plurality of ultrasonic transducers is adopted, and the transmission oblique angle probe in the extending direction of the fixed arm 53A is adopted. The transmission refraction angle of the transmission oblique angle probe 21 (indicated by θ _1a and θ _1b in FIG. 9, where θ _1a ≠ θ _1b ) is variably controlled according to the position of the tentacle 21, and the fixed arm 53B It is conceivable to variably control the receiving refraction angle of the receiving oblique angle probe 22 according to the position of the receiving oblique angle probe 22 in the extending direction (known phased array method). However, in this case, the entire system (particularly, the probe and the transmitter / receiver) becomes expensive and large. Further, even if the array probe is adopted, the presence of the pressing mechanism 55 and the gimbal mechanism 56 has a complicated influence on the position and orientation of the probe, so there are many design considerations.

FIG. 10 is a bottom view of the lower mirror portion showing the structure of the probe moving device 23 in the present embodiment, and FIG. 11 is a vertical sectional view of the lower mirror portion according to the middle cross section XI-XI of FIG. 10 and 11 show a case where the scanning point D of the welding boundary surface 13a is relatively deep. FIG. 12 is a bottom view of the lower mirror portion showing the structure of the probe moving device 23 in the present embodiment, and FIG. 13 is a vertical sectional view of the lower mirror portion according to the middle cross section XIII-XIII of FIG. 12 and 13 show a case where the scanning point D of the welding boundary surface 13a is relatively shallow. Note that in FIG. 11 and FIG. 13 shows transmission refraction angle theta _{1 'of} the apparent when projected transmission path S ₁ in cross-section XI-XI or cross-section XIII-XIII.

The probe moving device 23 of the present embodiment has a swing angle σ ₁ of the oblique angle probe 21 for transmission and reception when the scanning point D of the welding boundary surface 13a is moved in the depth direction of the lower mirror portion. From the viewpoint of keeping the swing angle σ ₂ of the oblique angle probe 22 constant, the annular track rail 30 extending along the circumferential direction of the welded portion 13 and the track rail 30 move along the track rail 30. It has drive devices 31A and 31B. Drive 31A, the circumferential direction swing angle sigma ₁ of transmitting the angle probe 21 for generating line direction K ₁ of the outer surface 12a of the lower mirror petal portions 12 at the moving position of _(and thus, the swing angle of the apparent ρ while fixing the _1), and is configured to move the transmission angle probe 21 along a generatrix direction K _1. Drive 31B, the circumferential direction swing angle sigma ₂ of receiving the angle probe 22 for generating line direction K ₂ of the outer surface 12a of the lower mirror petal portions 12 at the moving position of _(and thus, the swing angle of the apparent ρ while fixing the _2), and is configured to move the receiving angle probe 22 along a generatrix direction K _2.

Specifically, the driving device 31A includes a drivable mobile 32A the track rail 30 above, slidable in the generatrix direction K ₁ of the outer surface 12a of the lower mirror petal portions 12 in the circumferential direction position of the moving body 32A As described above, it has an arm 33A provided on the moving body 32A. The arm 33A has a swing angle adjusting mechanism 34A provided at an end opposite to the track rail 30, and supports a transmission oblique angle probe 21 via the swing angle adjusting mechanism 34A. .. Drive 31B includes a moving body 32B which can travel track rail 30 above, the mobile 32B in the generatrix direction K ₂ of the outer surface 12a of the lower mirror petals 12 so as to slidably in the circumferential direction position of the moving body 32B It has an arm 33B provided. The arm 33B has a swing angle adjusting mechanism 34B provided at an end opposite to the track rail 30, and supports a receiving oblique angle probe 22 via the swing angle adjusting mechanism 34B. .. Swing angle adjusting mechanism 34A, 34B is, for example, the transmitting angle probe 21 in accordance with the structural dimensions of the subject swing angle sigma ₁ and swing angle sigma ₂ of receiving the angle probe 22, respectively It is for changing the settings, and consists of a manually adjusted rotating stage and the like.

Then, in response to a command from the control device 25 regarding the circumferential position of the scanning point D, the position of the moving body 32A and the position of the moving body 32B in the extending direction of the track rail 30 are controlled. Further, in response to a command from the control device 25 regarding the depth of the scanning point D, the position of the moving body 32A and the sliding position of the arm 33A with respect to the moving body 32A (and by extension, the transmission oblique angle in the extending direction of the arm 33A). The position of the probe 21) is controlled, and the position of the moving body 32B and the sliding position of the arm 33B with respect to the moving body 32B (by extension, the position of the receiving oblique probe 22 in the extending direction of the arm 33B). It is designed to be controlled.

In the probe moving device 23 of the present embodiment configured as described above, since the contour of the outer surface 12a of the mirror petal portion 12 in the extending direction of the arm 33A is straight, it is used for transmission in the extending direction of the arm 33A. Regardless of the position of the oblique probe 21, the distance between the arm 33A and the outer surface 12a of the mirror petal portion 12 is the same. Therefore, unlike the comparative example, the pressing mechanism 55 that presses the transmission oblique angle probe 21 against the outer surface 12a of the mirror petal portion 12 is unnecessary. Further, regardless of the position of the transmission oblique angle probe 21 in the extending direction of the arm 33A, the normal direction H of the outer surface 12a of the mirror petal portion 12 and the direction I perpendicular to the extending direction of the arm 33A are the same. Is. Therefore, unlike the comparative example, the contact between the transmission oblique angle probe 21 and the outer surface 12a of the mirror petal portion 12 can be ensured without providing the gimbal mechanism 56.

For the same reason, the pressing mechanism 55 that presses the receiving oblique angle probe 22 against the outer surface 12a of the lower mirror petal portion 12 and the posture of the receiving oblique angle probe 22 are moved to the outer surface 12a of the lower mirror petal portion 12. The gimbal mechanism 56 to follow is unnecessary. Therefore, the probe moving device 23 can be simplified and downsized. Further, since the gimbal mechanism 56 does not exist, the detection sensitivity can be increased without adopting the array probe.

Further, the probe movement device 23 of the present embodiment, the arms 33A, since 33B are slidable structure generatrix direction _K 1, _{K 2} of the outer surface 12a of the lower mirror petal section 12, the arms 33A, 33B and RIP The oblique angle probes 21 and 22 can be arranged on the welded portion 13 side of the interfering portion while avoiding interference with the interfering portion such as the casing 15. As a result, the inspectable range can be expanded. Further, since the probe moving device 23 of the present embodiment has the swing angle adjusting mechanisms 34A and 34B, for example, the one probe method is applied to a shallow range other than the range U shown in FIG. It is also possible to carry out. Therefore, the one-probe method can be carried out without exchanging the device, and the inspection time can be shortened.

Next, the flaw detection conditions of the present embodiment will be described. In the present embodiment, in the transmission path S ₁ in the virtual plane C (horizontal plane) as described above so as to transmit ultrasonic waves, and the interference of the transmission angle probe 21 and the lower mirror petal section 12 The transmission refraction angle θ ₁ and the swing angle σ ₁ of the transmission oblique angle probe 21 are set (fixed) so as to avoid interference. Further, to avoid interference at the receiving path S ₂ in the virtual plane C to receive ultrasound, and an interference portion of the receiving angle probe 22 and the lower mirror petal section 12, reception The reception refraction angle θ ₂ and the swing angle σ _{2 of the} oblique angle probe 22 are set (fixed).

First, the point that sets the transmission at paths S ₁ to transmit ultrasound transmission refraction angle theta ₁ and swing angle sigma ₁ of transmitting the angle probe 21 in the virtual plane C .. Figure 14 is a vertical sectional view in the generatrix direction K ₁ of the outer surface 12a of the lower mirror petal portion 12 corresponding to the position of the transmission point P ₁ of the transmission angle probe 21, a transmission angle probe It is a figure for demonstrating the relationship between the swing angle σ _{1 of} 21 and the apparent transmission refraction angle θ ₁ '.

As shown in Figure 14, Assuming that the swing angle sigma ₁ of transmitting the angle probe 21 is set to 0 degrees, the actual transmission refraction angle theta ₁ and the transmission angle of refraction apparent theta _{1 'is} the same Become. At this time, the transmission refraction angle θ ₁ of the transmission oblique angle probe 21 (in the present embodiment, within the range of 60 to 80 degrees, for example, 70 degrees) is the inclination angle β of the outer surface 12a of the mirror petal portion 12. If it is larger than (for example, 57 degrees), the transmission direction vector u ₀ deviates to the lower side in FIG. 14 with respect to the virtual plane C. Then, if the swing angle σ ₁ of the transmission oblique angle probe 21 is made larger than 0 degrees, the apparent transmission refraction angle θ ₁ ′ becomes smaller, and the deviation angle ε of the transmission direction vector u with respect to the virtual plane C becomes smaller. ₁ can be 0 degrees.

The vector a representing the direction of the transmission oblique angle probe 21 is expressed by the following equation with the swing angle σ ₁ of the transmitting oblique angle probe 21 and the inclination angle β of the outer surface 12a of the mirror petal portion 12 as variables. It is represented by (1). T in equation (1) is the transpose symbol of the vector.

The transmission direction vector u is represented by the following equation (2) from the normal vector n and the vector a of the outer surface 12a of the mirror petal portion 12 with the transmission refraction angle θ ₁ of the transmission oblique angle probe 21 as a variable. Will be done.

If vertical component u _z direction of transmission vector u is zero, since the transmission direction vector deviation angle epsilon ₁ of u with respect to the virtual plane C becomes 0 degrees, the ideal swing angle indicated by the following formula (3) sigma The arithmetic expression of ₁ can be derived. That is, the ideal swing angle σ ₁ when the deviation angle ε ₁ = 0 degree is the inclination angle β of the outer surface 12a of the mirror petal portion 12 and the transmission refraction angle θ ₁ of the transmission oblique angle probe 21. It can be calculated and set from.

FIG. 15 is a diagram showing a specific example of the relationship between the swing angle σ ₁ of the transmission oblique angle probe 21 and the deviation angle ε ₁ of the transmission direction vector u with respect to the virtual plane C (horizontal plane). A specific example of this is the case where the inclination angle β = 57 degrees and the transmission refraction angle θ ₁ = 70 degrees, and the ideal swing angle σ ₁ = 55.9 degrees when the deviation angle ε ₁ = 0 degrees. Become. The swing angle σ ₁ can be fixed without depending on the depth of the scanning point D of the welding boundary surface 13 a .

By the same method as above, the transmission refraction angle θ ₂ and the swing angle σ ₂ of the receiving oblique angle probe 22 are set so that the ultrasonic waves are received in the reception path S ₂ in the virtual plane C. Can be done. In the present embodiment, the receiving refraction angle θ ₂ of the receiving oblique angle probe 22 is within the range of 60 degrees to 80 degrees, and is the same as the transmitting refraction angle θ ₁ of the transmitting oblique angle probe 21. It is set to the same value. Further, the swing angle σ ₂ of the reception tilt angle probe 22 is an ideal swing angle when the deviation angle ε ₂ = 0 degree of the reception direction vector with respect to the virtual plane C, and is a transmission tilt angle. It is set to the same value as the swing angle σ _{1 of the} angle probe 21.

Next, the transmission refraction angle θ ₁ and the swing angle σ ₁ of the transmission oblique angle probe 21 are set so as to avoid interference between the transmission oblique angle probe 21 and the interference portion of the mirror petal portion 12. The set points will be captured and explained. 16, the center axis _{O r} of the received point _P 2, RIP casing 15 of the transmission point _{P 1,} the receiving angle probe 22 for transmitting the angle probe 21 in the virtual plane C (horizontal plane), and the lower It is a figure which shows the positional relationship of the central axis O of a mirror part.

For determining the presence or absence of interference of the transmission angle probe 21 for RIP casing 15 and interfering portion consisting of R portions 15a of the periphery thereof as shown in Figure 16, about the central axis O _r the RIP casing 15 assume a circular interference region 40 having an interference radius R _I. The interference radius R is the sum of the radius of the RIP casing 15, the maximum width of the R portion 15a, and the radius of the virtual circle circumscribing the transmission oblique angle probe 21 with the transmission point P ₁ as the center.

In the circumferential range V of the welding boundary surface 13a shown in FIG. 16 (specifically, the range sandwiched by two straight lines circumscribing the circular interference region 40 through the central axis O of the lower mirror portion), the welding boundary surface The depth of the scanning point D in 13a makes it difficult to apply the one-probe method, and the two-probe method is applied. Then, in order to avoid interference between the transmission oblique angle probe 21 and the interference portion of the lower mirror petal portion 12 in the circumferential range V of the welding boundary surface 13a, the transmission oblique angle probe 21 is transmitted. the distance between the center axis _{O r} of the point P ₁ and RIP casing 15 needs to exceed the interference radius _{R I.} Than if the central scanning point D of the circumferential range V of the welding boundary surface 13a is located, it is better when the scanning point D on the end portion of the circumferential extent V of the welding boundary surface 13a is located, transmitting beveled feeler the distance between the center axis _{O r} transmission points P ₁ and RIP casing 15 of the child 21 is shortened. Therefore, in the latter case, it is necessary to distance between the center axis O _r transmission points P ₁ and RIP casing 15 of the transmission angle probe 21 to confirm whether the above interference radius R _I.

In order to avoid interference between the transmission oblique angle probe 21 and the interfering portion of the mirror petal portion 12, the swing angle σ ₁ of the transmission oblique angle probe 21 is increased and shown in FIG. The apparent swing angle ρ ₁ may be increased. The apparent swing angle ρ ₁ is expressed by the following equation (4), and if the transmission refraction angle θ ₁ of the transmission oblique angle probe 21 is relatively large (in the present embodiment, it is described above). (In the range of 60 to 80 degrees), the apparent swing angle ρ ₁ also increases.

Then, based on this apparent swing angle ρ ₁ , if geometric analysis is performed by the cosine theorem or the sine theorem, the transmission oblique angle probe corresponding to the depth of the scanning point D of the welding boundary surface 13a is performed. can be calculated the position of the transmission point P ₁ of 21, further capable of calculating the distance between the center axis O _r transmission points P ₁ and RIP casing 15 of the transmission angle probe 21.

FIG. 17 shows a transmission point P of the transmission oblique angle probe 21 that changes according to the depth of the scanning point D when the scanning point D is located at the end of the circumferential range V of the welding boundary surface 13a. is a diagram showing a specific example of the distance between the center axis O _{r 1} and RIP casing 15. Specific examples of this include an inclination angle β = 57 degrees, a transmission refraction angle θ ₁ = 70 degrees, a swing angle σ ₁ = 55.9 degrees, and a distance R _d between the central axis O of the mirror portion and the welding interface 13a. = 2500 mm, which is the case of the distance _R r = 3000 mm, the interference radius _R I = 250 mm between the center axis _{O r} of the center axis O and RIP casing 15 of the lower mirror portion. When the depth of the scanning point D of the welding boundary surface 13a is about 135mm, the distance between the center axis O _r transmission points P ₁ and RIP casing 15 of the transmission angle probe 21 is the minimum value although, it exceeds the interference radius _{R I.} Therefore, the transmission refraction angle θ ₁ and the swing angle σ ₁ of the transmission oblique angle probe 21 are set so as to avoid interference between the transmission oblique angle probe 21 and the interference portion of the mirror petal portion 12. You can see what you are doing.

By the same method as above, the reception refraction angle θ ₂ and the swing of the receiving oblique angle probe 22 are avoided so as to avoid interference between the receiving oblique angle probe 22 and the interference portion of the mirror petal portion 12. It can be confirmed that the angle σ ₂ is set.

In the above embodiment, the ideal swing angle sigma ₁ when the shift angle epsilon _{1 =} 0 degree, an ideal swing angle sigma ₂ when the shift angle epsilon _{2 =} 0 ° The case of setting has been described as an example, but the present invention is not limited to this, and the conditions of the deviation angle ε ₁ or ε ₂ may be changed as long as it is within the spread of the ultrasonic beam. The half-width of the ultrasonic beam varies depending on the size of the probe and the angle of refraction, but is generally less than 10 degrees. Therefore, the deviation angle ε ₁ of the transmission beam axis of the transmission oblique angle probe 21 with respect to the virtual plane C and the deviation angle ε ₂ of the reception beam axis of the reception oblique angle probe 22 with respect to the virtual plane C are -10. It may be allowed as long as it is within the range of 10 degrees. Therefore, for example, when the inclination angle β = 57 degrees and the transmission refraction angle θ ₁ = 70 degrees as shown in FIG. 14 above, the swing angle σ ₁ of the transmission oblique angle probe 21 is 26 degrees to 77 degrees. It may be allowed as long as it is within the range of the degree. Similarly, for example degree inclined angle beta = 57, when a reception angle of refraction theta _{2 =} 70 degrees, the swing angle sigma ₂ for reception angle probe 2 2, in the range up to 77 degrees from 26 degrees If there is, it may be allowed.

Further, in the above embodiment, the probe arm 33A of the mobile device 23, mobile 32A in the circumferential generatrix direction K ₁ in slidable manner mobile 32A of the outer surface 12a of the lower mirror petal portion 12 in the direction position provided, the arm 33B is, a case provided on the moving body 32B in the generatrix direction K ₂ of the outer surface 12a of the lower mirror petals 12 so as to slidably in the circumferential direction position of the moving body 32B has been described as an example However, the modification is possible without departing from the spirit and technical idea of the present invention. Arm 33A is, for example, an air cylinder or the like, may be provided in a mobile body 32A stretchable as the outer surface 12a generatrix direction K ₁ of the lower mirror petal portions 12 in the circumferential direction position of the moving body 32A. The arm 33B is, for example, an air cylinder or the like, be provided in the mobile 32B as stretchable as possible generatrix direction K ₂ of the outer surface 12a of the lower mirror petal portions 12 in the circumferential direction position of the moving body 32B Good. In such a modification, even when an interfering object is present on the dome portion 11 side (specifically, when a control rod drive mechanism inserted in the CRD housing 14 is present, for example, during an inspection during service). Interference between the interfering object and the arms 33A and 33B can be avoided.

Further, in the above embodiment, the case where the moving bodies 32A and 32B of the probe moving device 23 are configured to be able to travel on the track rail 30 extending along the circumferential direction of the welded portion 13 is an example. Explained to, but not limited to this. That is, the moving bodies 32A and 32B need only be configured to be movable along the circumferential direction of the welded portion 13, and have, for example, magnetic wheels for adsorbing to the outer surface of the lower mirror portion and traveling. You may be. Even in such a modified example, the same effect as that of the above-described embodiment can be obtained.

Further, in the above embodiment, the swing angle adjusting mechanism 34A capable of setting and changing the swing angle σ ₁ of the transmission oblique angle probe 21 and the swing angle σ ₂ of the receiving oblique angle probe 22 are provided. The case of having the swing angle adjusting mechanism 34B whose setting can be changed has been described as an example, but the present invention is not limited to this. That is, although the effect that it can be applied to a plurality of subjects having different structural dimensions cannot be obtained, it is not necessary to have the swing angle adjusting mechanisms 34A and 34B.

In the above, the welded portion 13 of the lower mirror portion of the reactor pressure vessel has been described as an example of the inspection target of the present invention, but the present invention is not limited to this, and a subject having a side surface shape of a truncated cone (or a cone) is used. It may be a cylindrical welded portion having a weld boundary surface inclined with respect to the thickness direction perpendicular to the surface.

12 Mirror petal part 12a Outer surface (surface)
13 Welded part 13a Welded boundary surface 15 RIP casing 15a R part 17 Internal defect 21 Oblique angle probe for transmission 22 Oblique angle probe for reception 23 Detector moving device 30 Track rail 31A, 31B Drive device 32A, 32B movement Body 33A, 33B Arm 34A, 34B Swing angle adjustment mechanism

Claims (7)

A cylindrical weld having a weld interface inclined in the thickness direction perpendicular to the surface of the subject, which has a side shape of a cone or a truncated cone, is to be inspected, and is arranged on the surface of the subject for transmission. An ultrasonic inspection system that uses an oblique probe and a receiving oblique probe to detect internal defects that occur along the weld interface.
A virtual plane including a scanning point of the welding boundary surface and a normal vector of the welding boundary surface on the scanning point corresponding to the scanning point of the welding boundary surface to be moved in the depth direction of the subject and the subject. The transmission point of the transmission oblique angle probe and the receiving point of the receiving oblique angle probe are located on the intersection line where the surface of the sample intersects, and the transmission oblique angle probe and the A probe moving device for arranging the transmitting oblique probe and the receiving oblique probe so as to avoid interference between the receiving oblique probe and the interfering portion of the subject. Prepare,
The probe moving device is
The transmission oblique angle probe around the normal axis of the surface of the subject with respect to the generatrix direction of the surface of the subject at the moving position in the circumferential direction so as to be movable along the circumferential direction of the welded portion. A first drive device that moves the transmission oblique angle probe along the generatrix direction while fixing the swing angle of the
The receiving oblique angle probe around the normal axis of the surface of the subject with respect to the other generatrix direction of the surface of the subject at the movement position in the circumferential direction so as to be movable along the circumferential direction of the welded portion. It has a second drive device that moves the receiving oblique angle probe along the other bus direction while fixing the swing angle of the child.
The transmission oblique angle probe has a transmission refraction angle and the neck so as to transmit ultrasonic waves through a transmission path in the virtual plane and to avoid interference with the interference portion of the subject. The swing angle is set,
The receiving oblique angle probe has a receiving refraction angle and the neck so as to receive ultrasonic waves in the receiving path in the virtual plane and to avoid interference with the interference portion of the subject. An ultrasonic inspection system characterized by a set swing angle. In the ultrasonic inspection system according to claim 1,
The first drive device is configured so that the swing angle of the transmission oblique angle probe can be changed.
The second driving device is an ultrasonic inspection system characterized in that the swing angle of the receiving oblique angle probe can be set and changed. In the ultrasonic inspection system according to claim 1,
The first driving device is provided on the first moving body that can move along the circumferential direction of the welded portion and on the first moving body so as to be slidable in the generatrix direction of the surface of the subject. And has a first arm that supports the transmission oblique probe.
The second driving device is provided on the second moving body so as to be slidable in the bus direction of the surface of the subject on the second moving body and the second moving body that can move along the circumferential direction of the welded portion. An ultrasonic inspection system comprising a second arm that supports the receiving oblique probe. In the ultrasonic inspection system according to claim 1,
The first driving device is provided with a first moving body that can move along the circumferential direction of the welded portion and the first moving body that can expand and contract in the generatrix direction of the surface of the subject. And has a first arm that supports the transmission oblique probe.
The second driving device is provided with a second moving body that can move along the circumferential direction of the welded portion and the second moving body that can expand and contract in the bus direction of the surface of the subject. An ultrasonic inspection system comprising a second arm that supports the receiving oblique probe. In the ultrasonic inspection system according to claim 3,
An ultrasonic inspection system characterized in that the first and second moving bodies are configured to be able to travel on track rails extending along the circumferential direction of the welded portion. In the ultrasonic inspection system according to claim 1,
The transmission refraction angle of the transmission oblique angle probe and the transmission refraction angle of the transmission oblique angle probe so that the deviation angle of the transmission beam axis of the transmission oblique angle probe with respect to the virtual plane falls within a range of -10 degrees to 10 degrees. Swing angle is set,
The receiving refraction angle of the receiving oblique probe and the receiving refraction angle of the receiving oblique probe so that the deviation angle of the receiving beam axis of the receiving oblique probe with respect to the virtual plane falls within a range of -10 degrees to 10 degrees. An ultrasonic inspection system characterized by a set swing angle. In the ultrasonic inspection system according to claim 6,
Ultrasonography characterized in that the transmission refraction angle of the transmission oblique angle probe and the reception refraction angle of the reception oblique angle probe were set within a range of 60 degrees to 80 degrees. system.

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