JPH0315130B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an apparatus for measuring the external dimensions of a channel box of a nuclear fuel assembly for a boiling water reactor.

(Prior Art) The outer shape of a channel box may be measured after irradiation for purposes such as follow-up of irradiation characteristics.

Therefore, conventionally, the external dimensions of the channel box have been measured using an underwater television device or the like as necessary, but the measurement work and the processing of the measurement results are complicated.

Therefore, a method for measuring the outer dimensions of channel boxes using ultrasonic waves may be considered as a method to compensate for this drawback. This method applies ultrasonic waves sequentially emitted from an appropriate number of ultrasonic sensors installed vertically on a support frame along the channel box to the side of the channel box, until the ultrasonic waves are reflected by the channel box and received. This can be done by measuring the time.

That is, the distances from the transmitting/receiving surface to several points of one measurement position are determined individually in the time until reception, and this is performed for each measurement position to calculate the external dimensions of the channel box in the longitudinal direction.

However, when a fuel assembly exists in a channel box, the spent nuclear fuel assembly usually emits decay heat, and the calorific value is not uniform in the longitudinal direction of the nuclear fuel assembly, which makes it difficult to store spent fuel. The water temperature distribution around the channel box in the pool is non-uniform.

However, although the measurement uses an ultrasonic sensor, it does not take into account the difference in sound speed that changes depending on the water temperature. Therefore, the time detected by the ultrasonic sensor is measured based on the sound speed corresponding to the water temperature at each measurement location.
The calculated external dimensions over the entire length of the channel box do not represent the actual external dimensions, even if the measurement time to each measurement site remains the same.

(Object of the Invention) The present invention has been made to solve the above-mentioned problems, and when measuring and calculating the external dimensions of channel boxes with different ambient water temperature distributions in a spent fuel storage pool, it is necessary to An object of the present invention is to provide an apparatus for measuring the external dimensions of a channel box that can perform accurate measurements by taking into account the speed of sound.

(Structure of the Invention) That is, the features of the present invention are as follows:
The invention consists of a distance detecting body in which an appropriate number of ultrasonic sensors arranged in a straight line are arranged in the same horizontal plane, and a distance detecting body in which an emission from one is received by the other when the distance detecting body is in substantially the same plane as the distance detecting body. A second aspect of the present invention is an external dimension measuring device in which a sonic velocity detector consisting of a pair of ultrasonic sensors arranged as shown in FIG. A suitable number of the devices are provided with external dimension calculation means for determining the external dimensions of the channel box using the sound speed calculated from the time measured by the distance detector and the time measured by the sound velocity detector. At the point.

(Example) Hereinafter, specific embodiments of the present invention will be described in detail in sequence based on the accompanying drawings.

FIG. 1 shows a channel box external dimension measuring device 10 according to the present invention in a spent fuel storage pool 1.
1 is a diagram showing how the external dimension measuring device 10 is installed in the swimming pool in use, and the external dimension measuring device 10 is installed so as to face a channel box 3 that is suspended along the wall surface 1a of the pool.

As is clear from the figure, this measuring device 10 mainly includes an external dimension measuring means 11 that measures the longitudinal external dimension of the channel box 3, and calculates the actual external dimension of the channel box 3 based on the measured value. It consists of calculation means 21.

Of these, the external dimension measuring means 11 is a basic measuring device of the present invention, and its details are as shown in FIG. 2. As shown in FIG. is preferably reflected from the side surface of the channel box 3.
As shown in the figure, a distance detecting body 13 is arranged to be perpendicular to each other in a horizontal plane, and a pair of ultrasonic waves are arranged on the same plane as the distance detecting body 13, one of which emits and the other which receives the ultrasonic waves. It is constructed by mounting a sound velocity detector 15 consisting of a sensor 14 on a sensor support stand 16.

As shown in FIGS. 1 and 2, the sensor support stand 16 is fixed to a support frame 17 fixedly installed on the wall surface 1a of the spent fuel storage pool 1 with, for example, U-bolts 18, and is fixed in a planar shape. An appropriate number of tubes are arranged at positions corresponding to the measurement target portions of the channel box carried into the approximately L-shaped measuring device 10.

Furthermore, when the ultrasonic sensor 12 is installed,
Usually, they are mounted so that they are on the same vertical plane. An operation panel 19 is provided on the upper part of the support frame 17 for instructing the ultrasonic sensors 12 and 14 to transmit and receive ultrasonic waves.

On the other hand, the external dimension calculation means 21 is installed on the ground above the pool;
is the distance detecting object 1 in the basic measuring device described above.
3 and the time measured by the sound velocity detector 15, the external dimensions of the channel box 3 are calculated with temperature correction added.

Both the first and second aspects of the present invention are constructed as described above, and the operation thereof will be explained below.

In FIG. 1, first, one of the channel boxes 3 containing the irradiated nuclear fuel assembly is suspended by a fuel exchanger 2 running over a storage pool 1 and placed on a wall surface 1.
The sample is transferred to the external dimension measuring device 10 provided at a. In this case, since the planar shape of the measuring device 10 is substantially L-shaped, they can be placed adjacent to each other very easily.

Next, when the movement of the channel box 3 stops, the operation panel 19 causes the ultrasonic sensors 12 and 14 of the distance detector 13 and the sonic velocity detector 15 mounted on each sensor support 16 to emit ultrasonic waves. .

At this time, the ultrasonic sensor 1 of the distance detector 13
The ultrasonic waves from 2 are reflected from the measurement site of the channel box 3, and the time until they are received again is measured. At the same time as this measurement or with a slight time delay, a signal is transmitted from one of the ultrasonic sensors 14 of the sound velocity detector 15 to the other ultrasonic sensor 14, and the time until reception is measured.

If the ultrasonic waves from the ultrasonic sensor 14 are brought close to the channel box 3 so as not to hit them as shown in FIG. In addition, the mounting positions of the ultrasonic sensors 14 should be separated as much as possible (Lo in the figure).
If the time is longer, the time required to determine the speed of sound becomes longer, and the accuracy of the measurement can be improved accordingly.

In this way, measurements are carried out one after another on the sensor support base 16 at the required locations, and if necessary, the channel box 3 may be reversed 180 degrees to take measurements on the other two sides of the measurement location.

The times measured by the ultrasonic sensors 12 and 14 described above are input to the computer of the external dimension calculating means 21, and the external dimensions are calculated there based on the above-mentioned times.

In other words, the time ti( ) measured by the ultrasonic sensor is the distance between the ultrasonic sensors 14 installed at intervals of (Lo) in advance, and the speed of sound at that point is calculated as Lo/ti. Note that if the correlation between water temperature and sound speed is known as shown in FIG. 3, the sound speed may be determined by directly detecting the water temperature using a temperature sensor or the like. The one-way time to the measurement point of the channel box measured by the ultrasonic sensor 12 at this speed of sound
By multiplying by Ti/2, the true distance (Lo·Ti/2ti) to the measurement site of the channel box is calculated. Therefore, when distances are measured at several points on the measurement points of the channel box and the relative positions of each are determined, the distances of the channel box 3 are determined as shown in Fig. 4a and b. External dimensions in the longitudinal direction can be calculated.

In addition, a sensor support stand 20 is equipped with a distance detector 13 and a sound velocity detector 15 similar to those described above at positions corresponding to the upper or lower part of the channel box 3 in the upper and lower parts of the large number of sensor support stands 16.
is provided, even if the channel box 3 is suspended by the fuel exchanger 2 and swings slightly, for example, if the position of its lower part is measured and at the same time the distance of one of the above-mentioned measurement points is measured, , it becomes possible to measure the external dimensions based on the lower position.

Thus, the external dimensions of the channel box can be accurately measured using the measuring device of the present invention.

The above description has been made regarding the case of a distance detecting body in which the ultrasonic sensors shown in FIG. 2 are arranged orthogonally to each other. 5
As shown in the figure, the ultrasonic sensor 12 is arranged only on one line on the sensor support stand 16, and the sound velocity detector 15
It may be installed together with the ultrasonic sensor 14 facing the channel box 3, and the same effect will be obtained.

(Effects of the Invention) As explained in detail above, the present invention includes a distance detecting body in which an appropriate number of ultrasonic sensors arranged in a straight line are arranged orthogonally in a horizontal plane, and A sonic velocity detecting body consisting of a pair of ultrasonic sensors arranged on the same plane, and a supporting frame body in which an appropriate number of sensor supports on which the sonic velocity detecting body and the distance detecting body are mounted are disposed vertically. of the channel box using an external dimension measuring device having an external dimension measuring device having an external dimension measuring means comprising the device, and the sound velocity calculated from the time measured by the distance detecting body and the time measured by the sound speed detecting body. Since it is configured with an external dimension calculation means for calculating external dimensions, it is possible to combine not only time measurement by the ultrasonic sensor of the distance detecting object but also measurement of transmission and reception time by the ultrasonic sensor of the sound velocity detecting object. In particular, highly accurate temperature correction is performed by matching the ultrasonic paths of the distance detector and the sonic detector in a water area with the same temperature. The external dimensions of the channel box under different distribution conditions can be accurately measured as the actual external dimensions, which has a remarkable effect on improving measurement accuracy.

Note that this measuring device can also be applied to fuel assemblies.

[Brief explanation of drawings]

FIG. 1 is an installation diagram of the external dimension measuring device of the present invention;
Figure 2 is a plan layout showing details of the measuring means;
The figure is a correlation diagram between water temperature and sound speed, Figures 4a and b are diagrams of the measurement state of the external dimensions of the channel box, and Figure 5
The figure is a plan view showing another example of arrangement of ultrasonic sensors. 3... Channel box, 3a... Upper channel box, 3b... Lower channel box, 10... External dimension measuring device, 11... External dimension measuring means, 12, 14... Ultrasonic sensor, 1
3... distance detector, 15... sound speed detector, 16,
20...Sensor support stand, 17...Support frame body.

Claims (1)

[Scope of Claims] 1. A distance detecting body in which an appropriate number of ultrasonic sensors arranged in a straight line are arranged in a horizontal plane, and a distance detecting body that is located in almost the same plane as the distance detecting body so that transmission from one side is transmitted to the other side. A device for measuring the external dimensions of a channel box, characterized in that a sound velocity detection body consisting of a pair of ultrasonic sensors arranged so as to emit a sound is mounted on a sensor support stand in each of the above arrangements. 2. The external dimension measuring device for a channel box according to claim 1, wherein the sensor support has an L-shape in plan view, and the ultrasonic sensors of the distance detectors are arranged on the support to be perpendicular to each other. 3 A distance detecting body in which an appropriate number of ultrasonic sensors arranged in a straight line are arranged perpendicularly to each other in a horizontal plane, and a distance detecting body that is located approximately in the same plane as the distance detecting body, and transmission from one side is received by the other. External dimension measuring means comprising an appropriate number of sensor support stands each equipped with a sonic velocity detection body consisting of a pair of ultrasonic sensors arranged in the above-mentioned arrangement on a support frame arranged in the vertical direction. and external dimension calculation means for calculating the external dimensions of the channel box using the sound velocity calculated from the time measured by the distance detector and the time measured by the sound velocity detector. A device for measuring the external dimensions of channel boxes. 4. The channel box external dimension measuring device according to claim 3, wherein the sensor support base has an L-shape in plan view. 5. An apparatus for measuring external dimensions of a channel box according to claim 3 or 4, wherein a sensor support is disposed at a measurement target position of the channel box.