JPH0315131B2 - - 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 the 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, as a method to compensate for this drawback, a method of measuring the external dimensions of channel boxes using ultrasonic waves is considered. 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 each measurement position of the channel box, and receives the ultrasonic waves reflected by the channel box. This can be done by measuring the time until

In other words, the distance from the transmitting/receiving surface to several points at one measurement position is determined individually in the time it takes to receive the signal, and this is performed for each measurement position.
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 external dimensions over the entire length of the channel box calculated using the measurement time up to each measurement position do not represent the actual external dimensions.

(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 It is an object of the present invention to provide an apparatus for measuring the external dimensions of a channel box that can perform accurate measurements taking into account the speed of sound.

(Structure of the Invention) That is, the present invention is characterized by: a distance detecting body in which an appropriate number of linearly arranged ultrasonic sensors are arranged in a horizontal plane; A sound velocity detector consisting of a pair of ultrasonic sensors arranged so that transmission from one side is received by the other is mounted on a center support stand that can be raised and lowered on a vertically erected guide body. External dimensions for determining external dimensions of a channel box using an external dimension measuring device attached to the arrangement, a sound velocity calculated by the time measured by the distance detector, and the time measured by the sound velocity detector. The point is that it is configured to include a calculation means.

(Example) Hereinafter, specific embodiments of the present invention will be described in detail 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. A distance detecting body 13 is arranged to be perpendicular to the horizontal plane so that the transmitted signal is reflected from the side surface of the channel box 3, and a distance detecting body 13 is disposed on the same plane as the distance detecting body 13, one of which emits and the other which receives it. A sound velocity detector 15 consisting of a pair of ultrasonic sensors 14 is attached to a center support base 16.

This sensor support stand 16 has a substantially L-shaped planar shape, and as shown in FIG.
It is mounted so as to be movable up and down, and can be moved to a position corresponding to the measurement position of the channel box 3 carried in to be adjacent thereto.

The storage pool 1 near the guide body 17
An operation panel 19 is provided above to instruct the ultrasonic sensors 12 and 14 to transmit and receive ultrasonic waves.

In addition to the above configuration, a distance detector 13 similar to that described above and a sound velocity detector are separately provided above or below the sensor support base 16, which can be raised and lowered, at a position corresponding to the upper or lower part of the channel box 3. Sensor support stand 2 with body 15 attached
It is also preferable to fix the channel box 3 to the guide body 17, so that the external dimensions of the swinging channel box 3 can also be measured as described later.

On the other hand, the external dimension calculation means 21 calculates the external dimensions of the channel box 3 based on the time measured by the distance detector 13 and the sound velocity detector 15 by adding temperature correction, and usually
It is installed above the ground above the pool.

The present invention has the configuration described above,
Next, its operation will be explained.

In FIG. 1, first, one of the channel boxes 3 is suspended in the spent fuel storage pool 1 by a fuel exchanger 2 running above the storage pool 1, and an external dimension measuring device is installed near the wall surface 1a. Transfer to 10. 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 ultrasonic sensors 12 and 14 of the distance detector 13 and the sonic velocity detector 15 mounted on the sensor support stand 16 facing the channel box 3 are controlled by the operation panel 19. Transmit more ultrasonic waves.

At this time, the ultrasonic sensor 1 of the distance detector 13
The ultrasonic waves from 2 are reflected from the measuring surface 4 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, the ultrasonic sensor 1 of the sound velocity detector 15
4 is transmitted to the other ultrasonic sensor 14, and the time until reception is measured.

As shown in FIG. 2, if the ultrasonic waves from the ultrasonic sensor 14 are brought close enough that they do not hit the channel box 3, the area in which the ultrasonic waves from the ultrasonic sensor 12 propagate can be measured. In addition, the mounting positions of the ultrasonic sensors 14 can 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, the sensor support base 16 is moved one after another to the required measurement positions by an elevating drive device such as an air cylinder, and measurements are performed at those positions.
When the measurement of all two sides of the measurement site facing the sensor support stand 16 is completed, the channel box 3 is further turned over by 180 degrees if necessary, and the other two sides of each measurement position are also measured. At this time, if observation using the underwater television camera 23 is required, the sensor support stand 16 may be moved together with the underwater television camera head 18.

The time measured by the ultrasonic sensor 12, 14 described above is input to the computer of the external dimension calculation means 21, and the external dimension is calculated there based on the time.

That is, based on the time ti measured by the ultrasonic sensor 14 and the distance between the ultrasonic sensors 14 installed in advance at an interval of Lo, the speed of sound at that point can be determined as Lo/ti. Note that if there is a correlation between the water temperature and the speed of sound as shown in FIG. 3, the speed of sound may be determined by directly detecting the water temperature using a temperature sensor or the like. By multiplying this sound speed by the one-way time Ti/2 to the measurement position measured by the ultrasonic sensor 12, the true distance to the measurement position (Lo·Ti/2ti) is calculated. Therefore, by measuring the distances of several locations at each measurement location and finding their relative positions, the external dimensions of the channel box 3 in the longitudinal direction can be calculated as shown in FIGS. 4a and 4b. Can be done.

In addition, above or below the sensor support 16 that moves up and down as described above, a sensor support is provided with a distance detector 13 and a sound velocity detector 15 similar to those described above, at a position corresponding to the upper or lower part of the channel box 3. 20, even if the channel box 3 is slightly oscillating, for example, by measuring the position of its lower part and simultaneously measuring the distance of one of the above measurement positions, its outer shape can be determined with the lower part as a reference. Dimensions can be measured.

Thus, the external dimensions of the channel box can be accurately measured by 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 are arranged orthogonally to each other, but the distance detecting body 13 does not necessarily have to have the ultrasonic sensors arranged orthogonally to each other, for example, as shown in FIG. Alternatively, the ultrasonic sensor 12 may be arranged only on one line on the sensor support base 16, and together with the ultrasonic sensor 14 of the sonic velocity detector 15, they may be installed facing the channel box 3, and the same effect can be achieved.

(Effects of the Invention) As described above in detail, the present invention includes 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 sound velocity detector consisting of a pair of ultrasonic sensors arranged in the outer shape, and a sensor support base to which the sonic velocity detector and the distance detector are mounted and which can be raised and lowered on a guide body installed in the vertical direction. dimension measuring means; and external dimension calculating means for determining the external shape of the channel box using the sound velocity calculated from the time measured by the distance detecting body and the time measured by the sound speed detecting body. In particular, by arranging the sound velocity detector for temperature correction in almost the same horizontal plane as the distance detector, the ultrasonic paths of the distance detector and the sound velocity detector are made to match in the same temperature water area, allowing highly accurate temperature correction. By synergizing the measurement times of both detectors, the external dimensions of the channel box under different ambient temperatures due to decay heat of spent nuclear fuel assemblies can be measured as true external dimensions. .

Furthermore, in the above device, since the sensor support base is movable up and down, there is no need to arrange a large number of ultrasonic sensors, the configuration is simplified, and the measurement operation on the operation panel is also simplified. In addition, depending on the stopping position of the sensor support stand, it has the advantage of being able to freely measure any part of the channel box, which is extremely useful in improving measurement accuracy in measuring the external dimensions of the channel box. .
Note that the measuring device can also be applied to fuel assemblies.

[Brief explanation of the drawing]

FIG. 1 is an installation diagram of the external dimension measuring device of the present invention;
Figure 2 is a plan layout of the external dimension measuring means, Figure 3 is a correlation diagram between water temperature and sound speed, Figures 4 a and b are diagrams of the measurement state of channel box external dimensions, and Figure 5 is a diagram of the ultrasonic sensor arrangement. FIG. 7 is a plan view showing another embodiment. 3... Channel box, 10... External dimension measuring device, 11... External dimension measuring means, 12, 1
4...Ultrasonic sensor, 13...Distance detector, 1
5...Sonic velocity detector, 16, 20...Sensor support base, 17...Guiding body, 21...External dimension calculation means.

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 substantially on the same plane as the distance detecting body and transmits from one side. External dimension measurement in which a sound velocity detection body consisting of a pair of ultrasonic sensors arranged so as to emit signals to the other is mounted in the above arrangement on a sensor support stand that can be raised and lowered on a guide body erected 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 channel box external dimension measuring device characterized by: 2. The channel box external dimension measuring device according to claim 1, wherein the sensor support base has a substantially L-shaped planar shape. 3. The channel box external dimension measuring device according to claim 1 or 2, wherein the sensor support base is integrally constructed with an underwater television camera head mounted on the guide body so as to be movable up and down. 4. Fix a sensor support stand with the same configuration as the sensor support stand on which both of the detection bodies are attached to a position corresponding to the upper and/or lower part of the channel box, and measure the external dimensions of the stationary or swinging channel box. An apparatus for measuring external dimensions of a channel box according to any one of claims 1 to 3.