JPS62134509A - Automatic sound-speed correcting type supersonic dimension measuring gate - Google Patents

Abstract

PURPOSE:To accomplish temperature correction of a measured distance to a specimen by multiplying a ratio of actual distance from a stylus and a wire and a measuring distance by a supersonic wave by a measured distance from the stylus to the specimen by the supersonic wave. CONSTITUTION:A supersonic wave stylus 10 is arranged corresponding to each measuring point of a specimen, such as a channel box 1, mounting a temperature correcting wire 11 between each stylus and measuring surface and the whole assembly is immersed in the water 12. The water temperature has generally been changed to t' deg.C, a different temperature from the initial temperature condition t deg.C an apparent distance of the wire 11 measured by the No.1 pulse meter 15 assumes a distance of L'W and the corresponding voltage VW is obtained by the No.1 distance voltage generator 16. A reflected wave from the channel box 1 is measured for the distance LS' by the No.2 pulse meter 17 and the corresponding voltage VS is obtained by the No.2 distance voltage generator 18. An arithmetic operation of a correcting coefficient VW/VW' is made from the initial voltage VW stored in a memory 14 through a correcting coefficient calculator 19. A product of the distance voltage VS' and correcting coefficient VW/VW' is obtained for the correction thereof.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to an automatic sound speed correction type ultrasonic dimension Y-A measuring device, and particularly to a device that uses ultrasonic waves in the water of a fuel pool in use or in a spent nuclear fuel channel box. The present invention relates to an automatic speed-of-sound correction type ultrasonic dimension measuring device suitable for automatically correcting fluctuations in measured values due to changes in water temperature when measuring dimensions.

[Background of the invention]

First, the background of the present invention will be explained using FIGS. 7 and 8M. Figure 7 is a perspective view showing the arrangement of the fuel channel box and control rods inside the reactor, and Figure 8 is the P of Figure 7.
In the directional view, four channel boxes 30 are arranged to surround one control rod 31, and the control rod 31 moves up and down in the gap between each channel box 30 to control the reactivity of the reactor core. do.

By the way, the channel box 30 undergoes deformations such as bulging of the square cross section, bending in the longitudinal direction, and twisting between the upper end and the lower end due to the thermal history received during the operation of the nuclear reactor. If this amount of deformation becomes large, a small portion will appear in the gap between each channel box 30, which will impede movement of the control rod 31. For this reason, it has become necessary to periodically measure the amount of deformation of the channel box 30 during use to confirm that there is no problem in driving the control shaft 31.

By the way, in the past, when manufacturing a channel box at a factory, what were the finished dimensions of the channel box? At present, this type of deformation measurement has not been carried out except for the determination of III. However, since the channel box after being used in the furnace is radioactive, it is not possible for an inspector to measure the dimensions directly by applying a scale to it, as is the case when it is manufactured in a factory, so it is naturally preferable to measure it remotely.
Furthermore, in order to avoid damaging the surface of the channel box, it is advantageous to perform measurements underwater without contact, and it has been considered to perform measurements underwater using ultrasonic waves. Well-known examples include sonar used in diving boards and fish finders equipped on fishing boats, but both of these are used for the above purpose because the speed of sound changes due to temperature. I can't.

[Object of the Invention] The present invention has been made in view of the above, and its purpose is to efficiently and accurately measure the dimensions of objects underwater by correcting changes in the speed of sound due to water temperature. An object of the present invention is to provide an automatic sound speed correction type ultrasonic dimension measuring device that can perform the following.

[Summary of the invention]

A feature of the present invention is that a wire serving as an ultrasonic reflector is placed at a known distance from the probe to the object to be measured, and the actual distance from the probe to the wire and the distance measured by the ultrasonic wave are measured. By multiplying the distance measured by the ultrasonic wave from the probe to the object to be measured by the ratio of The present invention is configured to include an automatic speed of sound correction means that enables temperature correction of distance.

[Embodiments of the invention]

Hereinafter, the present invention will be explained by the embodiments shown in FIGS.
This will be explained in detail using FIGS.

First, the principle of the present invention will be explained using FIGS. 3 to 6. Figure 3 is a diagram showing changes in ultrasonic underwater sound speed due to changes in water temperature, where the horizontal axis represents water temperature 'r.

The graph shows the speed of sound C on the vertical axis. From Figure 3, the water temperature is 0.
When changing from ℃ to 60℃, the sound speed is about 150m/sec
It can be seen that the

Figure 4 is a principle diagram of the ultrasonic dimension measuring device of the present invention;
The figure shows an example of the display on the CRT screen in the case of Fig. 4. (a) shows the ultrasonic flaw detection A scope waveform at water temperature t°C, and (b) shows the ultrasonic flaw detection IA scope waveform at t''C. It shows.

In FIG. 4, 23 is a high frequency cable, 24 is a water immersion ultrasonic probe, 25 is water, 26 is a wire, and 27 is an object to be measured. @
When a wire 26 is placed at Lw and an ultrasonic wave is irradiated from the probe 24 to a treasure 27 located at a distance Ls, when the water temperature is t°C.

The ultrasonic wave Hw is reflected from the wire 26, the ultrasonic wave Hs is reflected from the object to be measured 27, and as shown in FIG.
The reflected echo HIE from the wire 26 is displayed at the position,
The reflected echo H8E from the object to be measured 27 is displayed at the position Ls. 6 Next, when the water temperature reaches L'°C (t'>t),
As shown in FIG. 5(b), the reflected echo HwE' from the wire 26 is displayed at the position Lw', and the reflected echo H8' from the object to be measured 27 is displayed at the position Ls'.

Here, Lw: Ls=Lw': Ls' - (
1), by transforming this, Lw' is established. Therefore, by multiplying Ls/ by Lw/Lw' as a temperature correction coefficient, the distance Ls from the ultrasonic probe 24 to the object to be measured 27 can be accurately measured regardless of changes in water temperature.

Figure 6 is a diagram showing an example of the results, and shows the ultrasonic probe 2.
4 shows the relationship between water temperature T and measurement distance when the distance Ls from 4 to the object to be measured 27 is 20 mm and the water temperature T is changed from 20° C. to 50° C. The 8th curve in Figure 6 is the 4th curve.
In the case shown in the figure, the 5th curve is the wire 26 shown for comparison.
In the conventional case where no curve is provided, in the case of 8 curves, the water temperature T is 2
Even if the temperature changes from 0 to 50°C, the temperature is corrected by the wire 26, so the measurement error is suppressed to within about 0.05mm. Approximately 0.9+nm with temperature change from °C to 50 °C
This results in measurement errors.

FIG. 1 is a structural diagram showing an embodiment of the temperature correction mechanism section of the automatic sound speed correction type ultrasonic dimension measuring device of the present invention, in which (a) is a longitudinal cross-sectional view, and (b) is an A-A in (a). This is a line sectional view illustrating a case where the object to be measured is a nuclear fuel channel box. In FIG. 1(a).

1 is a channel box, 2 is a measuring device, measuring device 2
, seven ultrasonic probes 3 for measuring bending are arranged in the axial direction of the channel box 1, and four on each side of the periphery. The temperature correction wire 4 is tensioned.

Further, as shown in FIG. 1(b), one ultrasonic probe 5 for width measurement is arranged on each side of the circumference, and two ultrasonic probes 6 for torsion measurement are arranged only on one side. Temperature correction wires 7 and 8 are stretched in front of the probes 5 and 6, respectively. Note that 9 is a hanging wire that hangs the measuring device 2.In actual measurement, the channel box 1, in which the measuring device 2 is set, is moved in the axial direction while the fuel pool water or spent fuel inside the nuclear power plant is being moved. Performed in storage pool water.

FIG. 2 is a block diagram showing an embodiment of the temperature correction device of the automatic sound speed correction type ultrasonic dimension measuring device according to the present invention. Ultrasonic probes 1o are arranged corresponding to each measurement point of the channel box 1, which is the object to be measured, and a temperature correction wire (reflective wire) is placed between each probe 10 and the training surface of the channel box 1. body) 11 is attached and submerged in water 12 in this state.

When starting measurement, first, the reflected wave from the wire 11 is measured for each measurement point, and the voltage Vw corresponding to the distance LW is stored in the storage device 14 via the multiplexer 13.

Next, the channel box 1 is measured, but since the water temperature at this time is generally t"C, which is different from the initial condition, the apparent value of the wire 11 measured by the first pulse measuring device 15 is The distance is Lw', and the first distance voltage generator 16 generates a voltage Vw' corresponding to Lw'.
6 On the other hand, the reflected wave from the channel box 1 is caught by the second pulse measuring device 17 and the distance Ls
' is measured and a corresponding voltage V s ' is obtained by the second distance voltage generator 18.

Next, a method of correcting the distance when the temperature changes from the initial condition t'C to t'C will be described. A correction coefficient calculation unit 19 calculates a correction coefficient Vw/
Calculate Vw'.

Next, the correction calculator 20 calculates the channel box 2
The product of the distance voltage Vs' corresponding to the apparent distance up to 1 and the correction coefficient Vw/Vw' is calculated, and the voltage corresponding to the corrected true distance Ls is output from the output terminal 21.

Note that the above calculation process may be performed by a digital computer in addition to analog calculation, and the calculation process remains unchanged.

Note that 22 in FIG. 2 is an ultrasonic pulse generator.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to correct the change in the speed of sound due to 2 degrees of water and efficiently measure the dimensions of an object underwater with high accuracy.

A series of conventional operations such as measuring water temperature, calculating sound speed, converting 2 time axes, and calculating distance can be omitted.

This method has the advantage of being able to perform sub-determination in a high-dose radiation atmosphere.

[-! J-Explanation, FIG. 1 is a structural diagram showing an embodiment of the temperature correction mechanism section of the automatic sound speed correction type ultrasonic dimension measuring device of the present invention.

FIG. 2 is a block diagram showing an embodiment of the temperature correction device, FIG. 3 is a diagram showing changes in ultrasonic underwater sound speed due to changes in water temperature, and FIG. 4 is a diagram showing the ultrasonic dimension measuring device of the present invention. FIG. 5 is a diagram showing an example of a display on a CRT screen in the case of FIG. 4, and FIG. 6 is a diagram showing an example of measurement results in the case of FIG. 4.

FIG. 7 is a perspective view showing the arrangement of fuel channel boxes and control rods within the reactor, and FIG. 8 is a view taken in the direction of arrow P in FIG. 7.

1... Channel box (object to be measured), 2... Measuring device, 3, 5, 6, 1.0... Ultrasonic probe, 4,
7゜8.11...Wire, 12...Water, 13...Multiplexer, 14...Memory'! A position, 15... first pulse measuring device, 16... first distance voltage generator, 17
...Second pulse measuring device, 18...Second distance voltage generator, 19...Correction coefficient calculator, 2o...Correction calculator,
22...Ultrasonic Pal (and 1 other person) χ) Diagram (α) You 2 De Diagram 3 T ('C) -→ 躬5因(α) (b) 躬60 r (''c) □

Claims (1)

[Claims] 1. When determining the dimensions of an object to be measured by measuring distance underwater from the propagation time of ultrasonic waves, a wire serving as an ultrasonic reflector is placed at a known distance from the probe to the object to be measured. , Measure the water temperature and change the water temperature by multiplying the distance measured by the ultrasonic wave from the probe to the object to be measured by the ratio of the actual distance from the contact to the wire and the distance measured by the ultrasonic wave. 1. An automatic sound measurement correction type ultrasonic dimension measuring device characterized by comprising an automatic sound speed correction means that enables temperature correction of the measurement distance to the object to be measured without calculating changes in ultrasonic sound speed due to the ultrasonic sound speed change.