JPH0536730B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an apparatus for measuring the shape of a channel box of a nuclear reactor fuel assembly, particularly a boiling water reactor fuel assembly, using ultrasonic waves.

(Conventional technology) When a channel box is used in a furnace, the pressure on the inside becomes higher than the outside, so it gradually swells due to creep deformation. In addition, bending occurs due to non-uniformity in the amount of irradiation growth. Therefore, when reusing a channel box, it is necessary to confirm that the channel box is not bent or bulged within a certain specified value.

Therefore, an underwater television device is used to measure the external dimensions of channel boxes, and an ultrasonic reflection method using ultrasonic waves is used to make measurements faster and more accurate. The latter is mainly used for measurements.

Figures 3 and 4 show measurement methods currently being attempted using the ultrasonic reflection method to measure the shape of channel boxes.
The ultrasonic sensors 12 are placed around the control rod storage rack 13, for example, and the fuel assembly is moved up and down, and the ultrasonic sensors 12 are placed between each ultrasonic sensor 12 and the channel box 11 at an arbitrary axial position. The distance is measured based on the time from transmission to reception of the ultrasonic wave, and the data is processed according to the block diagram shown in Figure 5 to determine the state of deformation, such as bending of the channel box on the outer periphery of the fuel assembly, bulge in the cross section, etc. Measuring.

(Problem to be Solved by the Invention) By the way, in order to measure the amount of bulge etc. using the ultrasonic reflection method described above, at least three pieces of data are required on one side due to the accuracy of the data. At least three sensors are arranged. However, when three sensors are arranged, if the measurement bulge is large, signals are often not returned to the two sensors at both ends, as shown in FIG.

That is, the ultrasonic sensor is not suitable for detecting a surface that is tilted with respect to the ultrasonic sensor due to its sharp directivity, and if the measurement is tilted by a few degrees, it will soon become impossible to detect the surface.

Therefore, as the bulge of the measurement surface becomes larger, it is necessary to increase the number of sensors, which naturally increases the cost of the device. In addition, it is necessary to position the channel box with respect to the ultrasonic sensor, and it is difficult to obtain an accurate profile with only three pieces of position information.

The present invention addresses the above-mentioned circumstances and solves the above-mentioned problems by swinging the ultrasonic sensor to align the direction of ultrasonic travel with the detection surface, and by detecting the swing rotation angle. The purpose of this method is to accurately measure the profile of the channel box detection surface even if the bulge is large, without increasing the number of ultrasonic sensors.

(Means for Solving the Problems) That is, the features of the present invention that meet the above objectives include: an apparatus for measuring the shape of a channel box using an ultrasonic sensor as described above;
The ultrasonic sensor is made swingable so that the angle of inclination of the measuring part (ultrasonic wave reflecting part) of the channel box can be determined in addition to the distance between the ultrasonic sensor and the channel box. The present invention is equipped with a data processing device including software for accurately determining the profile of the channel box external shape based on the obtained data.

(Function) According to the device of the present invention having the above configuration,
Since the ultrasonic sensor swings, it continuously measures the shortest distance from the tip of the sensor to the surface of the channel box while swinging. Then, the angle of the ultrasonic sensor at this time is measured with an encoder (rotation angle measuring device).

Based on the distance and angle information thus obtained, the ultrasonic reflection point on the channel box surface is uniquely determined, and at the same time, the inclination of the tangent to the channel box surface at that point, that is, the inclination angle is also calculated.

By the way, since three sets of ultrasonic sensors are usually arranged on each side, three sets of the above calculation results are obtained for each side, and based on this data, an accurate profile of that side can be drawn. .

Next, by applying this mechanism to the four sides of the channel box and arranging 12 ultrasonic sensors, it becomes possible to draw the profile of each side and obtain an accurate cross-sectional profile of the channel box.

(Example) Next, an example of the apparatus of the present invention will be described with reference to the accompanying drawings.

1 and 2 are a partial plan view and a side view showing one example of the main part of the measuring device of the present invention. In the figures, 1 is a channel box, and an ultrasonic sensor 2 is installed to measure the profile of one side of the channel box. Three are arranged side by side.

The ultrasonic sensor 2 is held in a holder block 3, an absolute type encoder 4 is connected to the upper part of the holder block 3, and a motor 6 is connected to the lower part of the holder block 3 through a gear box 5.

Of course, since each of these devices is underwater, it has a watertight structure, but this is omitted in the figure.

The shaft rotation of the motor 6 is converted into an oscillating (oscillating) motion within the gear box 5 based on a known method, and the holder block 3 and the ultrasonic sensor 2
swings around the central axis Z in the direction of the arrow.

Thus, the ultrasonic sensor 2 typically has a distance of several meters.
Ultrasonic waves are received and transmitted at intervals of sec, but by continuously measuring the distance to the channel box 1 while swinging the ultrasonic sensor 2, the sensor 2
The shortest distance from the tip to the surface of the channel box 1 is known, and the angle of the sensor 2 when the shortest distance is measured is determined by the attached encoder 4.

As described above, by performing data processing based on this distance and angle information, an accurate cross-sectional profile of the channel box can be obtained.

In this way, the fuel assembly can be moved up and down, and the deformation state of the channel box on the outer periphery of the fuel assembly can be measured at any axial position.

(Effects of the Invention) As described above, the device of the present invention is equipped with a mechanism for swinging the ultrasonic sensor, and is capable of swinging. Because some ultrasonic waves are not returned, it was necessary to install a large number of sensors, but in the present invention, the sensors swing, which expands the reception range, and three sensors per side of the channel box are sufficient. , the efficiency is significantly improved.

In addition, with the conventional ultrasonic fixed type, only the positional information of the ultrasonic reflection point on the channel box surface could be obtained, but with the sensor swinging method of the present invention, in addition to positional information, the tangent of the channel box surface at that point can be obtained. By being able to obtain slope data as well, there is a remarkable effect that a more accurate profile can be determined.

Furthermore, in the conventional ultrasonic sensor fixing method, it was necessary to position the measurement surface of the channel box at the most efficient angle relative to the sensor, but in the present invention, scanning is performed on the sensor side, so the positioning can be done roughly, making it easier to operate. There is also the advantage of having a good
Compared to conventional channel box shape measurement using ultrasonic waves, this method is expected to have a significant effect in improving accuracy and effectiveness.

[Brief explanation of drawings]

1 and 2 are a partial plan view and a side view showing the main parts of an example of the shape measuring device of the present invention, FIG. 3 is a schematic side view of the main parts of a conventional measuring device, and FIG. 4 is a main part of the conventional measuring device. FIG. 5 is a block diagram of the channel box shape measuring device. 1... Channel box, 2... Ultrasonic sensor, 5... Gear box, 6... Motor.

Claims (1)

[Claims] 1. In an apparatus for measuring the shape of a channel box using an ultrasonic sensor, the ultrasonic sensor arranged corresponding to the side of the channel box is capable of swinging, and the ultrasonic sensor and A device for measuring the shape of channel boxes, characterized in that the device is configured to be able to determine not only the distance between the channel boxes but also the angle of inclination of the measuring portion of the channel boxes. 2. The apparatus according to claim 1, further comprising a data processing device including software for obtaining a profile of the outer shape of the channel box based on both the distance and angle data obtained. measuring device.