JPH07104430B2 - Fuel rod ultrasonic flaw detection method and flaw detection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of use] The present invention relates to ultrasonic flaw detection inspection of welds of rod-shaped and pipe materials by fusion welding and solid-state welding, and particularly welding by pulse magnetic welding or TIG welding. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic flaw detection method and flaw detection apparatus for a weld defect of a fuel rod for a nuclear reactor.

[Conventional technology]

FIG. 11 is a view showing a welded portion of a fuel rod. FIG. 11 (a) is a sample by pulse magnetic welding, FIG. 11 (b) is a sample by TIG welding, and FIG. 12 is an ultrasonic wave of a conventional rod or pipe. FIG. 13 is an explanatory view of a flaw detection inspection method, and FIG. 13 is an explanatory view of a conventional ultrasonic flaw detection inspection method for a fuel rod welded portion. 12 is a material to be inspected, 13 is an A surface, 14, 14 ′
Is B surface, 15 is C surface, 16 is a central axis, 17 is a flaw detection area, 61 and 62 are end plugs, 63 and 64 are cladding tubes, 65 is a probe, 66 is a butt joint, and 67 is an object to be inspected. Material, 68 is a central axis.

The welding portion of the fuel rod as the material to be inspected is different from the ordinary rod material or pipe material, and as shown in FIGS. 11 (a) and 11 (b), the end plug 61
Or 62 and the cladding tube 63 or 64 are pulse magnetic welded or TIG welded, and the welded portion is A surface 13, B surface 14 or 14 '.
And C-face 15 have three different outer diameters.

Conventionally, when inspecting fuel rod welds with X-rays, X-rays are radiated from one side of the weld flaw detection area 17, and X-rays are taken on a photographic film placed on the side of the flaw detection area. Welding defects were determined.

Further, in ultrasonic flaw detection of a rod or tube, the ultrasonic probe 65 is fixed as shown in FIG. 12, and the material 67 is rotated left and right while the central axis 68 is an axis, The butt weld 66 had been inspected, but when trying to inspect a weld with a different outer diameter such as a fuel rod,
As shown in Fig. 13, the C surface 15 of the maximum diameter of the flaw detection area 17 of the test material 12
In order to adjust the water distance, the water distance changes on the A surface 13 and the B surface 14, and the sound pressure changes on the B surface 14 because the probe 63 is not perpendicular to the surface, and uniform inspection can be performed. There wasn't.

[Problems to be Solved by the Invention]

By the way, magnified imaging is not possible with X-ray inspection,
Check the size of the photographic film image for defects. Since the focal diameter of X-rays is large, on the order of mm, and the film naturally has a limit of resolution, so only defects of φ0.2 mm can be identified. In addition, a defect of about φ0.2 mm largely depends on the skill of the judge. Since a normal inspection is a plane in the XY2 direction, a lot of man-hours such as photographing and developing a photographic film are required to perform defect inspection in multiple directions. Furthermore, X
The line inspection requires a unique working space such as an irradiation room, an operation room, a dark film developing room, and a dark room for inspection, and since film development is performed, it is impossible to make an instantaneous inspection judgment.

The X-ray inspection has not only the above-mentioned drawbacks but also the transmission method. Therefore, in the case of solid-phase bonding, the images of the bonded part and the unbonded part overlap each other, and also in the case of solid-phase bonding. Since the pores are as small as 50 μm or less, they cannot be identified.

The focal diameter used for precision flaw detection in ultrasonic flaw detection is usually φ0.5 mm, but it should be 0.1 to 0.3 mm, which is about 1/10 to 1/20 of that used in X-ray inspection. Possible,
Since the reflected wave is received electrically, theoretically even a defect of 1 μm can be identified. However, it is actually 10 μm due to the attenuation in the substance and the echo caused by the grain size of the test material tissue.
It will be about. However, if the distance between the probe that oscillates ultrasonic waves and the test material is not constant, the intensity of the ultrasonic waves transmitted inside the test material changes, and a difference occurs in the echo from the defect inside the test material, It has a drawback that certain evaluation cannot be performed.

An object of the present invention is to provide a fuel rod ultrasonic flaw detection method and flaw detection device capable of inspecting a test material having a different outer diameter and inclination or curvature such as a welded portion of a fuel rod.

[Means for Solving the Problems]

The present invention is to rotate the fuel rod test material, at least a part of which is immersed in water, and move the ultrasonic probe along the surface of the test material in the axial direction of the test material to determine the outer shape of the test material. The surface of the test material that rotates while controlling the ultrasonic irradiation angle of the ultrasonic probe while maintaining a constant water distance between the ultrasonic probe and the surface of the test material based on the measurement data A fuel rod ultrasonic flaw detection method including a step of performing flaw detection by moving the ultrasonic probe along the test material in the axial direction of the specimen, and a water tank in which temperature-controlled water is injected within a predetermined temperature range, A rotation driving means which is inserted into the water tank and which rotationally drives the fuel rod test material immersed in water; and an ultrasonic probe driving means which moves the ultrasonic probe and changes the ultrasonic irradiation angle. , Controlling the rotation drive means, and ultrasonic probe based on the external shape data of the material to be inspected. The signal processing control means for controlling the ultrasonic wave driving means so as to irradiate the surface of the material to be inspected with ultrasonic waves vertically while maintaining a constant water distance between the surface of the material to be inspected and the signal processing control means. A display means for displaying flaw detection data is provided.

[Action]

The present invention first measures the outer shape of the test material by moving the ultrasonic probe in the axial direction of the fuel rod test material rotated in water, and then measures the outer shape of the test material based on the outer shape data. While maintaining a constant water distance, the probe is driven and controlled so that the ultrasonic irradiation angle is perpendicular to the surface of the material to be inspected, and flaw detection signals for the entire circumference of the material to be inspected are collected over the entire flaw detection area. It is possible to perform a defect inspection of the welded portion of the test material.

Embodiments Embodiments of the present invention will be described below with reference to the drawings.

1 to 4 are views showing an embodiment of an ultrasonic flaw detection method and a flaw detection apparatus for a fuel rod welded portion according to the present invention. FIGS. 1 (a), (b) and (c) are ultrasonic flaw detections, respectively. Front view, side view and bird's-eye view of a schematic view of the device body, FIG. 2 (a)
And (b) are a front view and a side view of a drive unit main body schematic view, FIG. 3 is a schematic view of a water tank unit, FIG. 4 is an ultrasonic flaw detection system configuration diagram, and FIG. 5 is a fuel rod welded portion outer diameter measuring method. Explanatory drawing, No. 6
FIG. 7 is a diagram for explaining a probe operation at the time of flaw detection of a fuel rod weld, FIG. 7 is a diagram showing a probe stroke range, FIG. 7A is a front view, FIG. 7B is a side view, and FIG. The figure shows the A-scope display, FIG. 9 shows the C-scope display, and FIG. 10 shows the B-scope display. The figures (a) and (b) are longitudinal section display and transverse section display, respectively. FIG. The thirteenth
The same numbers as in the figure indicate the same contents. Further, 1 is a drive unit main body, 2 is a pedestal, 3 is a constant temperature tank, 4 is a filter, 5 is a pure water producing device, 6 is a water circulation pump, 7 is a water storage tank, 11 is a probe, 21 is an X-axis servo. Motor, 22 is a Y-axis stepping motor, 23 is a Z-axis servo motor, 24 is a θ-angle servo motor, 25 is a rotation drive servo motor, 26 is a collect chuck, 27 is an internal water tank, 28 is an external water tank, and 29 is Aquarium saucer, 30
Is a cap, 31 is an air knife, 32 is a position detection stopper, 33 and 34 are overflow ports, 35 is an XY table, 36
Is a water inlet, 41 is an operation panel, 42 is an operation switch, 43 is a sequencer, 44 is a personal computer, 45 to 49 are motor drivers, 50 is a pulse transmitter, 51 is a CRT, 52 is an ultrasonic flaw detector, and 53 is an ultrasonic wave. The dimension measuring device 54 is a keyboard.

In FIG. 1, the main body of the present ultrasonic welding equipment for fuel rod welding comprises a probe drive system and a water circulation system, and the drive system operates a drive body 1 for operating an ultrasonic probe 11 provided on a gantry 2. The water circulation system includes a constant temperature bath 3, a filter 4, a pure water producing apparatus 5, a water circulation pump 6, a water storage tank 7, and the like.

Next, an outline of the probe drive system and the water circulation system will be described with reference to FIGS. 2 and 3.

As shown in FIG. 2, the drive system includes an X-axis servo motor 21, a Z-axis servo motor 23, an angle changing servo motor 24, and a Y-axis stepping motor 22 for driving the probe, and It has a servomotor 25 that rotationally drives the material to be inspected via a collect chuck 26 that holds the material to be inspected 12, and the probe is three-dimensionally driven while rotationally driving the material to be inspected 12 as described later in detail. In addition, it is possible to detect flaws by changing the ultrasonic irradiation angle from the probe.

The water circulation system has a structure in which the inner and outer tanks 27 and 28 are placed on the water tank tray 29. Considering the effect of radiation on the water of the fuel rods, the water tank is designed so that only the material to be inspected at the tip of the fuel rods is submerged. It is a local immersion type with a small tank volume.

As shown in FIG. 3, the water tank has a double structure of a cylindrical inner water tank 27 and an outer water tank 28 that covers the inner water tank 28. The water in the inner water tank 27 is scattered by the rotation of the test material 12 in the outer water tank 28. It is provided to prevent it from attaching and to attach an air knife 31 to be described later.
29 is provided.

A cap having a hole for passing the test material 12 at the right end of the internal water tank 27
30 is screwed in, this is replaced for each different outer diameter of the test material 12, and the hole diameter of the cap 30 is about 0.1 m from the outer diameter of the test material 12.
The material 12 to be inspected is thickened so as not to be damaged by rotation. Therefore, water flows through the material 12 to be inspected through this gap, or a large amount of water flows out when the material 12 to be inspected is removed from the water tank. Compressed air with a pressure of 3 to 6 kg / cm ² is blown to scatter the water transmitted through the material to be tested into the exterior water tank 28 to prevent the water from flowing out to the collect chuck 26 side. In addition, a probe is provided above the inner water tank 27 and the outer water tank 28.
The overflow ports 33 and 34 are provided only in the range where the 11 moves, so that the contact surface with the air is made as small as possible to prevent the water from becoming dirty due to dust or the like.

The water used in these circulation systems is the water tank 7 shown in FIG.
Then, the water circulation pump 6, the pure water producing device 5, the filter 4, and the constant temperature tank 3 are sequentially passed through, and then the water is circulated from the water supply port 36 to the inner water tank 28 and further to the outer water tank 29 to return to the water storage tank 7. The circulating water is purified to a certain level of water by the filter 4 and the pure water producing device 5,
Set temperature 20 ~ 40 ℃ by constant temperature bath 3 with heater and cooler
Against ± 0.5 ° C to keep the ultrasonic wave propagation velocity constant, and when the water temperature is poured into the empty interior water tank 27,
At about 10 to 15 ° C., a large number of bubbles are generated and adhere to the inner surface of the internal water tank 27, so deaeration is performed to prevent this.

Next, ultrasonic flaw detection according to the present invention will be described with reference to FIGS.

In FIG. 4, the sequencer 43 and the personal computer are operated by operating the keyboard 54 and the operation switches of the operation panel 41.
According to the program of 44, the motor drivers 45 to 48 are controlled, the servo motors 21, 23, 24 and 25 are driven to drive and control the probe of the ultrasonic flaw detector 52, and the test material is rotated. Driven. Further, the stepping motor 25 is directly driven from the sequencer via the pulse oscillator 50 and the motor driver 49, and is manually operated in the Y-axis direction when necessary. In this way, control of speed, feed pitch, position from the base point, etc. is performed.

In FIG. 7, the probe 11 is moved in three directions, that is, the horizontal direction (X axis) of the central axis 16 of the test material 12, the front-back direction (Y axis) and the vertical direction (Z axis) perpendicular to the central axis. Angle in XZ plane (θ)
The servo motors 21, 23 and 24 are used to manually or automatically control the movement in the X-axis and Z-axis directions and the change in θ, respectively.
(Fig. 4). The drive performance of each motor is as follows.

X-axis direction …… Stroke 0 to 100mm Minimum pitch 0.01mm Speed Max50mm / s Y-axis direction… Stroke 0 to 16mm Minimum pitch 0.01mm Speed-Z axis direction …… Stroke 0 to 50mm Minimum pitch 0.01mm Speed Max50mm / s θ …………… Stroke ± 30 ° Minimum pitch 0.01 ° Speed Max25 ° / s The rotational drive of the material 12 to be inspected is composed of an air open / close type collect chuck 26 and a servomotor 25 that fix the material to be inspected 12, The test material 12 is fixed to the collect chuck 26 by applying the tip to the position detection stopper 32. The material to be inspected 12 is a servo motor that can be manually or automatically controlled from 1 ° pitch feed to a maximum of 500 rpm.
It is driven to rotate at 25.

By driving the probe while rotating the test material by driving the motor as described above, first, the distance between the test material and the probe is measured by the ultrasonic dimension measuring device to determine the outer shape of the test material. Shape data is stored. Next, an echo from the test material is detected by the ultrasonic flaw detector based on the outer shape data, and the analysis result based on the data is displayed on the CRT 51. Note that the ultrasonic flaw detector 52 and the ultrasonic dimension measuring device 53 are actually the same probe. In addition,
In this device, ultrasonic waves with a frequency of 35 to 100 MHz are used, and an ultrasonic beam with a focal diameter of φ0.1 mm to 0.3 mm is used.

Next, the outer shape measurement and flaw detection method of the test material will be further described with reference to FIGS. 5 and 6.

In FIG. 5, the material to be inspected at the fuel rod welded portion has three different surfaces, that is, the A surface 13, the B surface 14 and the C surface 15 as described above. Therefore, the test material 12 installed below the probe 11 in the water in the water tank is rotated about the central axis 16,
While moving the probe 11 along the direction of the central axis 16, ultrasonic waves are radiated to measure the water distance from the test material 12, and the outer diameter and the gradient angle of the test material 12 are measured.

Next, based on the measured outer shape data of the test material 12, the sixth
As shown in the figure, the position of the probe in the same plane including the central axis 16 so that a constant water distance is maintained with respect to the surface of the rotating test material 12 and the ultrasonic irradiation angle becomes vertical. While controlling the direction, the A surface 13, B surface 14 and C surface 15 along the direction of the central axis 16
About flaw detection.

The welding flaw detection result is confirmed as image data as follows, unlike the waveform output and chart output that are performed in the normal ultrasonic inspection.

(A) Data collection Vertical coordinates are created from position information based on pulse signals output from the servo motor 21 for moving in the X-axis direction and the servo motor 25 for rotating the test material, and at the same time, the flaw detection signal is overlapped to form the data matrix. Turn into.

For example, at the X-axis base point 0 position of the test material, the test material 12 is rotated from a rotation angle of 0 to 359 degrees, the flaw detection signal at that time is collected, and this is repeated up to the X-axis flaw detection area x mm. , Collect data. At this time, the dividing powers in the X-axis direction and the circumferential direction can be arbitrarily changed from the minimum values of 0.01 mm and 1 degree, respectively.

This collected data includes the X-axis position, the rotation angle of the central axis, the presence / absence of a defect signal, the height of the defect signal, the position of the defect signal from the surface, etc., and is used for defect analysis by using the outer diameter value of the test material. To be done.

(B) Display of data The collected data can be imaged by various methods shown below and visually observed.

A scope display (defect waveform display) The waveform and position are displayed as shown in FIG.

In the display, the vertical axis represents the dimension in the X-axis direction and the horizontal axis represents the circumferentially expanded position of the test material, and the rising edge of the waveform is the echo height of the waveform.

C scope display (defect identification display) The data of A scope display is displayed on the color display at a maximum of 8 gradations with arbitrary thresholds, and the range, distribution and echo intensity of the defect are output as shown in FIG. To do.

Since there is a limit to the image on the display, there is a limit to the display of minute parts and defects. Therefore, in this system, it is possible to output them on the display and the degree of the defect in characters, and the division frequency It is also possible to enlarge the interval, display an enlarged image, and calculate the area from the number of dots.

B scope display (inspection material shape defect display) From the data of the C scope display and the outer diameter measurement data of the inspection material, as shown in FIGS. 10 (a) and (b), the position of the defect in the longitudinal section and the transverse section and The joining state can be confirmed.

These cross-sections are displayed by arbitrarily specifying the angle of the cutting position on the vertical cross section and the axial position on the horizontal cross section.It is possible to read the maximum bond length of the defect position and the unbonded length on the displayed image. It is possible.

For example, if the vertical cutting angle position θ is arbitrarily specified in the vertical cross-sectional display of FIG. 10 (a), the display screen has a specified cutting surface of θ upward and a cutting surface of θ ± 180 ° facing θ downward. Is displayed. Although θ can be specified at any position from 0 to 359 °,
Since the display direction of the screen is always constant, 0-180 ° is upward, 1
81 to 359 ° is displayed below. Select either the joined length or the unjoined length at that time and display it. The joining length Xmm in the 0 to 180 ° direction (specified position in the upper part of the figure) and the 181 to 359 ° direction The joint length Ymm is displayed.
Also in the cross-sectional display of FIG. 10 (b), it is possible to selectively display the length of the joint or the non-joint at the cutting position x mm.

In addition to this, image printer output, maximum joint length and maximum unjoint length and position, image display of maximum and minimum dimension measurement data value of outer diameter of test material and printer output, display of inspection result of pass / fail judgment and these It is possible to store the data of the above with a flop disk. In addition, these data can be called by attaching them to serial numbers, and arbitrary threshold values can be changed and data can be edited.

〔The invention's effect〕

As described above, according to the present invention, unlike the flat photographic film inspection of the X-ray inspection, a three-dimensional inspection of the entire circumference can be performed, and the defect resolution is about 0 of that of the X-ray inspection by using ultrasonic waves. .
Not only does it improve from 2 mm to 10 μm, but by visually observing weld defects with images, it is possible to perform inspections irrespective of the skill of the inspector and it is not necessary to separate the work space. It is possible to improve process simplification and labor saving.

Further, various data under inspection can be read out and analyzed at any time by storing and storing it in a floppy disk or the like.

[Brief description of drawings]

1 to 4 are views showing an embodiment of an ultrasonic flaw detection method and a flaw detection inspection apparatus for a fuel rod welded portion according to the present invention, and FIGS. 1 (a), (b) and (c) are ultrasonic waves, respectively. Front view, side view and bird's-eye view of the schematic view of the inspection apparatus body, FIG. 2 (a)
And (b) are a front view and a side view of a drive unit main body schematic view, FIG. 3 is a schematic view of a water tank unit, FIG. 4 is an ultrasonic inspection apparatus system configuration diagram, and FIG. 5 is a fuel rod welded portion outer diameter measurement. Operation explanation diagram,
FIG. 6 is an explanatory view of a probe operation at the time of flaw detection of a fuel rod weld,
The figure shows the probe stroke range. In the figure, (a) is a front view, (b) is a side view, FIG. 8 is a view showing A scope display, and FIG. 9 is a view showing C scope display. FIG. 10 is a view showing a B scope display, FIGS. 10A and 10B are views showing a vertical cross section display and a horizontal cross section display, respectively, and FIG. 11 is a view showing a welded portion of a fuel rod. (A) is a sample by pulse magnetic welding, (b) is a sample by TIG welding, FIG. 12 is an explanatory view of a conventional ultrasonic flaw detection method for a bar or pipe, and FIG.
The figure is an explanatory view of a conventional ultrasonic flaw detection method for a fuel rod weld. 1 ... Driving unit main body, 2 ... Stand, 3 ... Constant temperature bath, 4 ...
Filter, 5 ... Pure water production device, 6 ... Water circulation pump,
7 ... water tank, 11 ... probe, 12 ... test material, 17 ... flaw detection area, 21 ... X-axis servo motor, 22 ... Y-axis stepping motor, 23 ... Z-axis Servo motor, 24 …… θ-angle servo motor, 25 …… Rotating servo motor, 26 …… Correct chuck, 27 …… Internal water tank, 28 …… External water tank, 30
...... Cap, 31 …… Air knife, 36 …… Water inlet, 41
…… Control panel, 42 …… Operation switch, 43 …… Sequencer,
44 …… PC, 51 …… CRT, 52 …… Ultrasonic flaw detector, 5
3 ... Ultrasonic dimension measuring device, 54 ... Keyboard.

Claims (7)

[Claims] 1. An outer shape of a material to be inspected by moving an ultrasonic probe in the axial direction of the material to be inspected along the surface of the material to be inspected while rotating the material to be inspected at least partially immersed in water. At the stage of measuring the shape, while maintaining a constant water distance between the ultrasonic probe and the surface of the test material based on the measurement data, the test material that rotates while controlling the ultrasonic irradiation angle of the ultrasonic probe A fuel rod ultrasonic flaw detection method comprising a step of performing flaw detection by moving an ultrasonic probe along the surface in the axial direction of a test material. 2. A water tank in which temperature-controlled water is injected within a predetermined temperature range, a rotation driving means for rotating and driving a fuel rod test material which is inserted into the water tank and immersed in water, and an ultrasonic probe. While moving the probe, while controlling the ultrasonic probe drive means for changing the ultrasonic irradiation angle, and the rotation drive means, the ultrasonic probe and the surface of the test material based on the outer shape data of the test material. The signal processing control means for controlling the ultrasonic wave driving means so as to irradiate the surface of the material to be inspected with ultrasonic waves vertically, and a display for displaying flaw detection data from the signal processing control means. And a fuel rod ultrasonic flaw detector. 3. The fuel rod ultrasonic flaw detector according to claim 2, wherein the water tank comprises an internal water tank for immersing the fuel rod and an external water tank for accommodating the internal water tank to prevent water from splashing. 4. The internal water tank and the external water tank are inserted with a stopper penetrating one surface of the internal water tank and the external water tank until the fuel rod test material comes into contact with the stopper through the other surface facing the internal water tank. The fuel rod ultrasonic flaw detector according to claim 3, wherein an overflow port for moving the probe is provided on the upper surface of the outer water tank. 5. The surface of the internal water tank through which the fuel rod test material penetrates is
The fuel rod ultrasonic flaw detector according to claim 4, wherein the fuel rod ultrasonic flaw detector comprises a replaceable cap having a through hole for a test material. 6. The fuel rod ultrasonic flaw detection according to claim 4, wherein an air knife for blowing compressed air to the fuel rod is provided on the inner surface of the exterior water tank through which the fuel rod test material penetrates. apparatus. 7. The fuel rod ultrasonic flaw detector according to claim 2, wherein the display means is a CRT and is capable of selectively displaying a joint length or a non-joint length of a fuel rod weld portion.