JPS58223007A - Ultrasonic wave perspective image device - Google Patents

Abstract

PURPOSE:To obtain an accurate perspective image without errors, by obtaining the position of a floated fuel assembly, and using an echo level characteristic corresponding to the position. CONSTITUTION:Ultrasonic waves generated in liquid metallic sodium 104 are reflected by a reflecting plate 110, received by an ultrasonic transducdor 109, and outputted to a gate circuit 115 as an echo signal from the ultrasonic transducer 109. The position of a floated fuel assembly is detected by a floated fuel assembly position detector 118 based on the waveform of the echo signal. By using the echo level characteristic corresponding to the position of the detected position of the floated fuel assembly, the peak value, which is detected by a peak value detector 117, is corrected by a level correcting circuit 119.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ultrasonic fluoroscopy device for confirming the presence or absence of obstacles such as fuel assemblies floating above the core of a fast breeder reactor.

[Technical background of the invention]

Background technology will be explained with reference to FIGS. 1 and 2.

Figure 1 shows an ultrasonic fluoroscopy system that uses ultrasonic waves to detect obstacles present above the core of a sodium-cooled reactor, such as fuel assemblies floating above the core.
A cross-sectional view taken along the line ■-■ in the figure is shown.

In the figure, 1 is a reactor vessel of a sodium-cooled nuclear reactor that uses liquid metal sodium as a coolant. The upper part of is shielded by a shielding glove 5. In addition, a large number of fuel assemblies 6 are loaded into the core 2 and can be inserted and removed from above.
The nuclear fuel provided inside the nuclear fuel assembly 6 generates heat due to a nuclear fission reaction, and this heat is configured to heat the column 4 provided at the lower part of the reactor vessel 1. The heated sodium 4 is then allowed to flow out through a sodium outlet 8 provided at the top of the furnace vessel 1, passed through a heat exchanger (not shown), etc. provided outside the furnace vessel 1, and the cooled sodium is Sodium is allowed to flow in from population 7 again.

Here, inside the reactor vessel 1, the liquid metal sodium 4 flows through the reactor core 2 from the bottom to the top, so that the fuel assemblies 6 are likely to float up from the reactor core 2. 6A in the figure shows a fuel assembly floating above the core 2.

On the other hand, the core upper mechanism 3 located above the core 2 is
The control system consists of a one-rod drive mechanism and various measuring instruments.
, At the time of fuel exchange, the upper core mechanism 3 is moved horizontally to a position where it is removed from above the core 2, and the fuel exchange machine (
(not shown) must be located above the core 2.

Between the company status ``core'' and core 1 mechanism'' and 0 (Dllll! 1 (
(hereinafter referred to as 4,9 core gap) has only about 70 fins, so if the fuel assembly 6 inserted from above into the core 2 using a fuel exchanger is not inserted sufficiently to the lowest position of the core, or If some of the fuel assemblies 6 are floating as shown in 6A due to the flow of liquid metal sodium 4, if the upper core machine $s3 is moved horizontally, the fuel assemblies protruding upward from the core 2 will be removed. body 6
There is a risk that it will collide with A and destroy the fuel assembly. Therefore, before moving the core upper mechanism, it is necessary to carefully check whether there is any floating fuel assembly 6A protruding above the core 2. Here, core 2
The fuel assembly is submerged in liquid metal sodium 4, and in order to examine the state of the fuel assembly submerged in liquid metal sodium 4, a fluoroscopy device using ultrasonic waves with good visibility even in liquid metal sodium 4 is required. It will become. Therefore, an ultrasonic transducer 9 is installed on a part of the inner circumferential surface of the reactor vessel 1 at a position approximately at the same level as the upper end of the reactor core 2, and an ultrasonic reflector is mounted on the inner circumferential surface of the reactor vessel 1 opposite to the ultrasonic transducer 9. 10
Install it. When ultrasonic waves are emitted from the ultrasonic transducer 9 in this way, the ultrasonic waves emitted in the liquid metal 4 will be emitted from the ultrasonic transducer 9 if there are no obstacles in the core gap. The sound waves are not significantly attenuated while reaching the sound wave reflection plate 10,
The signal is reflected by the reflection plate 10, received by the ultrasonic transducer 9, and outputted from the ultrasonic transducer 9 as an echo signal. However, if there is any obstacle in the core gap, such as a fuel assembly floating above the core 2, the ultrasonic waves will be attenuated when passing through the core gap, and the echo signal will become extremely small. Therefore, by installing the reflector plate 10 in a wide arc shape and rotating the ultrasonic transducer 9 in the horizontal direction, it is possible to check the presence or absence of obstacles at each position on the reactor core. And if there is an obstacle somewhere above the core,
Since no echo signal is obtained when ultrasonic waves are emitted in that direction of the transducer, it is possible to know the presence of an obstacle, and furthermore, the presence of the obstacle can be determined from the position of the transducer in the turning direction at that time. You can also know the direction in which it exists.

The ultrasonic fluoroscopic apparatus for detecting obstacles as described above will be explained in more detail as follows. That is, outside the furnace vessel 1, there are an ultrasonic transducer drive mechanism 1 for rotating the ultrasonic transducer 9, and a position detection circuit 12 for detecting the position of the ultrasonic transducer 9 in the rotation direction.
, a nozzle 13 that sends excitation pulses to the ultrasonic transducer 9 in synchronization with the position change in the rotational direction of the ultrasonic transducer 9, a register (X14) that detects and amplifies the echo signal, and an ultrasonic reflector. a dart circuit 15 that allows only the echo signal to pass through; a timing circuit 16 that outputs a pulse trigger signal to the sensor 13 and outputs a dart time corresponding to the rotation angle of the ultrasonic transducer 9; a peak value detection circuit 17 that detects the peak value of the echo signal that has passed through the circuit 15;
An image processing circuit 18 that creates a fluoroscopic image signal indicating the state of the core gap from the position signal output from the position detection circuit 12 and the peak value of the echo signal output from the peak value detection circuit 17; and this image processing circuit. A display mechanism 19 for displaying a perspective image based on a perspective image signal from 18 is provided.

Further, the ultrasonic reflecting plate 10 is constructed as shown in FIG. That is, the ultrasonic beam excited by the ultrasonic transducer 9 is emitted with a two-dimensional spread.

For this reason, the reflector 10 is a combination of small reflectors subdivided in the circumferential direction, and steps Δatt- are provided between adjacent small reflectors so that the distance from the ultrasonic transducer 9 changes stepwise. The configuration is such that the reflected waves from each small reflection plate do not interfere with each other. If the spread angle υ of the ultrasound beam (hereinafter referred to as the irradiation angle) is ψ, then there are multiple (
In this example, 7) small reflectors 10) elOB,...1
The unit reflectors 10 configured by combining them in a stepwise manner cover the above-mentioned irradiation angle ψ, and a plurality of such unit reflectors 10f are arranged in an arc shape on the inner peripheral surface of the furnace vessel 1. be. The number of unit reflectors is determined to be enough to cover the area above the reactor cores 1 and 2 where ultrasonic waves should be seen through, as shown in FIG. Now, if we consider the state in which the center line of the ultrasonic beam emitted by the first ultrasonic transducer 9 is on the central small reflector 10D as shown in Figure 3,... Each small reflector 10A tloB as shown in
...A signal corresponding to the reflected wave from JOG is output,
Further, it is amplified by the receiver 14 and the echo signal Ea +
Eb't...+Kg. At this time, the largest echo signal is the small reflector 10D located on the center line of the ultrasound beam.
This is an echo signal Ed corresponding to a reflected wave from. Therefore, this maximum echo signal Ed is set as a reference measurement value Ep (Ep=Ed in this case), and the size of the soldering iron gap is determined from this reference measurement value and displayed on the image display device 19.

In order to obtain the core gap f"f from the maximum echo signal, for example, the relationship between the echo signal ratio and the core gap ratio as shown in FIG. In other words, in Fig. 5, the horizontal axis represents the ratio EpAps between the echo signal Eps and the reference measurement value Ep when there is no obstacle, and υ represents the ratio between the core 2 and the upper core mechanism 3. The ratio Q/Gs of the gap G8 to the core gap G is plotted on the vertical axis as the core gap ratio.

[Problems with background technology]

FIGS. 5 to 7 are diagrams showing differences in echo level characteristics depending on the position of a floating fuel assembly as an obstacle. In other words, in FIG. 5, the position of the floating fuel assembly is on the ultrasonic transducer 9 side! D (A), (B)
, (C). And each position (g),
(B), (In (1''), when the echo level is detected by changing the flying height of the floating fuel assembly 6A, it becomes as shown in FIG. 6. When the flying height is O, each position ( The echo levels at A) t (B) and (C) are the same value. However, the floating height ft (50%
), (70%), (90%) of each of the above positions (4),
The echo levels in (B) and (C) each show different values. In other words, even if the amount of floating υ is the same, different echo levels are detected depending on the position of the floating multi-fuel assembly.If this is expressed as an echo level characteristic as shown in Fig. 7, it will be detected depending on the position of the floating multi-fuel assembly. This results in different echo level characteristics. However, according to the configuration of the conventional example, signal processing is performed using the echo level characteristics shown in Figure 5 regardless of the position of the floating fuel assembly, which causes a problem of detection errors. [Objective of the Invention] The object of the present invention is to determine the position of a floating fuel assembly and use echo level characteristics corresponding to that position to eliminate errors and obtain accurate perspective images. The object of the present invention is to provide an ultrasonic fluoroscopy device that can perform

[Summary of the invention]

The ultrasonic fluoroscopy apparatus according to the present invention includes an ultrasonic transducer, a reflecting plate that is placed between the ultrasonic transducer and the object to be measured, and that reflects the ultrasonic □ waves emitted from the ultrasonic transducer. an ultrasonic transducer drive mechanism that rotates the acoustic transducer within a predetermined angle; an ultrasonic transducer position detection circuit that detects the rotation angle of the ultrasonic transducer; and a Gills signal for the ultrasonic transducer.

a receiver which outputs the signal, and a receiver which inputs and amplifies the echo signal detected by the ultrasonic transducer;
A gate circuit that opens and closes the path of the echo signal from the receiver, and a gate circuit that outputs a guru trigger signal to the transducer and corresponds to the transducer position detected by the ultrasonic transducer position detection circuit. A timing circuit that sets the gate time and outputs a trigger signal to the above e-) circuit, a peak value detection circuit that detects the peak value of the echo signal that has passed through the dirt circuit, and an echo No. 48 from the dirt circuit. an obstacle position detection circuit that detects the position of an obstacle in the object to be measured from the waveform of the peak value detection circuit; a level correction circuit that corrects the detected peak value;
This configuration includes a display mechanism that processes and displays the detection signal of the ultrasonic transducer position detection circuit and the signal from the level correction circuit.

In other words, the obstacle position detection circuit detects the position of the obstacle, and the level correction circuit corrects the peak value detected by the peak value detection circuit based on data corresponding to the detected obstacle position. .

Therefore, compared to the conventional method which uses the same data regardless of the position of the obstacle, a more accurate fluoroscopic image can be obtained and a highly accurate ultrasonic fluoroscope can be provided. [Embodiment of the invention] An embodiment of the present invention will be described with reference to FIGS. 9 to 13.

Fig. 9 shows an ultrasonic fluoroscopy system that uses ultrasonic waves to detect obstacles present in the upper part of the core of a sodium-cooled nuclear reactor, such as fuel assemblies floating above the core. This is a reactor vessel for a sodium-cooled nuclear reactor that uses liquid metal sodium.
04 etc. are accommodated, and the upper part of the reactor vessel 101 is equipped with a shielding plug 1.
It is shielded by 05. In addition, a large number of fuel assemblies 106... are loaded into the reactor core 102 so as to be able to be inserted and removed from above, and the nuclear fuel provided inside these fuel assemblies 106... generates heat through a nuclear fission reaction. The furnace is configured to use this heat to heat the liquid metal sodium 104 that flows in from the sodium inlet 107 provided at the bottom of the furnace vessel 101. And this heated sodium 10
4 to the sodium outlet 1 provided at the top of the furnace vessel 10
08, the cooled sodium is passed through a heat exchanger (not shown) provided outside the furnace vessel 101, and the cooled sodium is allowed to flow in again through the sodium inlet 107. liquid metal sodium 10
4 flows through the core 102 from bottom to top, the fuel assemblies 106 .

In the figure, 106A indicates a fuel assembly floating above the core 102.

On the other hand, the core upper mechanism 1 located above the core 102
03 consists of a control rod drive mechanism, various measuring instruments, etc. During fuel exchange, the core upper mechanism 103 is moved to the core 102.
A refueling machine (not shown) must be positioned above the core 102 in its place. However, the core 102 and the upper core mechanism 10
The gap between 3 and 3 (hereinafter referred to as core gap) is 70
If the fuel assemblies 105 inserted into the core 102 from above using a fuel exchanger are not inserted sufficiently to the lowest position of the core, or if the flow of liquid metal sodium 104 If some of the fuel assemblies 106 are floating as shown in 106A, if the core upper mechanism 103 is moved horizontally, the core 102
There is a risk that it will collide with the floating fuel assembly 106k that protrudes upwards and destroy that fuel assembly.

Therefore, before moving the core upper mechanism, it is necessary to carefully check whether there is any fuel assembly 106A protruding above the core 102. Here, the reactor core 102
In order to examine the state of the fuel assembly submerged in the IJum 104, and furthermore in the liquid metal sodium 104, fluoroscopy using ultrasound, which has good visibility even in the liquid metal sodium 104, is necessary. This requires equipment. Therefore, on a part of the inner peripheral surface of the reactor vessel 10, the core 10
The ultrasonic transducer 109 is installed at approximately the same level as the upper end of the furnace vessel 1 , and the
An ultrasonic reflecting plate 110 is attached to the inner peripheral surface 01'.

When the ultrasonic transducer 109 emits ultrasonic waves in this manner, the ultrasonic waves emitted in the liquid metal sodium 104 will be transmitted to the ultrasonic transducer 109 if there are no obstacles in the core gap. The waves are not significantly attenuated while reaching the ultrasonic reflecting plate 110, are reflected by the reflecting plate 110, are received by the ultrasonic transducer 109, and are outputted from the ultrasonic transducer 109 as an echo signal. However, if there is any obstacle in the core gap, such as a fuel assembly floating above the core 102, the ultrasonic waves will be attenuated when passing through the core gap, and the echo signal will become extremely small. Therefore, the reflecting plate 110 is installed widely in an arc shape,
By rotating the ultrasonic transducer 109 in the horizontal direction, the presence or absence of obstacles at each position on the core can be investigated. If an obstacle exists somewhere on the reactor core, the presence of the obstacle can be known because no echo signal is obtained when the transducer 109 is directed in that direction and transmits ultrasonic waves. Furthermore, the direction in which the obstacle exists can be determined from the position of the transducer in the rotation direction at that time.

The ultrasonic fluoroscope that detects obstacles as described above will be explained in more detail. Outside the furnace vessel 101 are an ultrasonic transducer drive mechanism 11) that rotates the ultrasonic transducer 109, and an ultrasonic transducer 1θ9.
a position detection circuit 112 that detects the position in the rotation direction of the ultrasonic transducer 109, a nockler 113 that sends an excitation pulse to the ultrasonic transducer 109 in synchronization with a change in the position of the ultrasonic transducer 109 in the rotation direction, and a receiver that detects and amplifies the echo signal. 114, a dirt circuit 115 that allows only the echo signal from the ultrasonic reflector to pass through, and the above-mentioned pulser 113
a timing circuit 116 that outputs a 79 pulse trigger signal and a dart time corresponding to the rotation angle of the ultrasonic transducer 109;
a peak value detection circuit 1171 that detects the peak value of the echo signal that has passed through the gate circuit 117; a floating fuel assembly position detection circuit 118 that detects the position of the floating fuel assembly from the waveform of the echo signal from the gate circuit 115; a level correction circuit 11 that corrects the peak value detected by the peak value detection circuit 117 based on data corresponding to the floating fuel assembly position detected by the floating fuel assembly position detection circuit;
9. An image processing circuit 120k and this image processing circuit 12 that generates a perspective image signal indicating the state of the core gap from the position signal output from the position detection circuit 112 and the peak value of the echo signal output from the level correction circuit 119.
An image display device 120B is provided which displays a perspective image based on a perspective image signal from 0k and constitutes a display mechanism 120 together with the image processing circuit 120A.

Next, the configuration of the floating fuel assembly position detection circuit 118 will be explained.

10 to 12 are diagrams showing the relationship between the number of echo signals (hereinafter referred to as the number of masks) for which the attenuation rate is 30% or less and the position of the floating fuel assembly 106A. In other words, FIG. For example, from the ultrasonic transducer Jo9 side, positions (A'), (B'), (C'
) there are floating fuel assemblies 106A at three locations 0
At this time, each position (A'), (B') e (c'
), as shown in FIG. 11, the number of masks decreases as the distance from the ultrasonic transducer 109 increases. Note that FIG. 12 is a diagram showing the number of masks at position (A'). The floating fuel assembly position detection circuit 118 is configured to detect the position of the floating fuel assembly '1o6A by measuring the number of masks.

That is, the floating fuel assembly position detection circuit 118 as shown in FIG. 13 stores an echo signal (eo) when there is no floating fuel assembly in the first waveform storage circuit 122, and The waveform storage circuit 123 stores an echo signal (e) for obtaining a fluoroscopic image. and division circuit 124
The echo signal (eO) of the above echo signal (,) is
Find the ratio (e/eo). Then, a comparison circuit 125 compares whether the above (e/so) becomes 0.7 or less, and a counter 126 calculates the number of echo signals that become 0.7 or less, that is, the number of masks.
Then, the position of the floating fuel assembly is detected by the number of masks, and the level correction circuit 119 uses the echo level characteristic corresponding to this position to cause the peak value detection circuit 11
This is a configuration that corrects the pixel value from 7.

Additionally, the ultrasonic reflecting plate 110 is constructed as shown in FIG. 3, as in the conventional example.

According to the ultrasonic fluoroscope with the above configuration, unlike conventional methods, the same echo level characteristics are used regardless of the position of the floating fuel assembly to obtain a fluoroscopic image of the core gap. First, the floating fuel assembly position detection circuit 11
8 to detect the position of the floating fuel assembly. Then, the peak value detected by the peak value detection circuit 117 is corrected by the level correction circuit 119 using the echo level characteristics corresponding to the detected position of the floating fuel assembly, making it possible to perform measurements with extremely high precision. This makes it possible to obtain perspective images with very small display errors. This not only prevents destruction of the fuel assembly 106 but also improves the safety of the nuclear reactor.

〔Effect of the invention〕

An ultrasonic fluoroscopy apparatus according to the present invention includes an ultrasonic transducer, a reflector that is placed between the ultrasonic transducer and the object to be measured, and reflects the ultrasonic waves emitted from the ultrasonic transducer, and the ultrasonic transducer. an ultrasonic transducer drive mechanism that rotates the ultrasonic transducer within a predetermined angle; an ultrasonic transducer position detection circuit that detects the rotation angle of the ultrasonic transducer; A dart circuit that inputs and amplifies the echo signal detected by the sonic transducer, a dart circuit that opens and closes the path of the echo signal from the receiver, and a pulse trigger signal that outputs a pulse trigger signal to the ultrasound transducer and the ultrasonic transducer position detection circuit. A timing circuit that sets the gate time corresponding to the detected transducer position and outputs a signal to the gate circuit, and a peak value detection circuit that detects the peak value of the echo signal that has passed through the dart circuit. a circuit, an obstacle position detection circuit that detects the position of an obstacle on the object to be measured from the waveform of an echo signal from the dirt circuit, and data corresponding to the obstacle position detected by the obstacle position detection circuit. A level correction circuit for correcting the peak value detected by the peak value detection circuit and a display mechanism for processing and displaying the detection signal of the ultrasonic transducer position detection circuit and the signal from the level correction circuit are provided. The configuration is as follows.

In other words, the obstacle position detection circuit detects the position of the obstacle, and the level correction circuit corrects the peak value detected by the peak value detection circuit based on the data corresponding to the detected obstacle position. be.

Therefore, compared to the conventional method that uses the same data regardless of the position of the obstacle, it is possible to obtain more accurate fluoroscopic images and to provide an ultrasonic fluoroscope with a high MW. .

[Brief explanation of drawings]

Figures 1 to 5 are diagrams showing conventional examples. Figure 1 is a schematic configuration diagram of an ultrasonic fluoroscopy system applied to detect obstacles on the top of the reactor core, and Figure 2 is the same as in Figure 1. −■ Cross section, 3rd
The figure shows the relationship between the ultrasonic transducer and the ultrasonic reflector, Figure 4 is a timing diagram of the echo signal output from the receiver, Figure 5 shows the relationship between the echo signal and the core gap, and Figure 6 shows the relationship between the echo signal and the core gap. Figures 8 through 8 are diagrams showing the relationship between the floating fuel assembly and the echo signal, Figure 6 is a diagram showing the position of the floating fuel assembly, and Figure 7 is the diagram showing the position of the floating fuel assembly and the echo signal. FIG. 8 is a diagram showing the relationship between the echo signal and the core gap by changing the flying height, and FIGS. 9 to 13 are diagrams showing an embodiment of the present invention. Fig. 9 is a schematic configuration diagram of the ultrasonic fluoroscope, Fig. 10 is a diagram showing the position of the floating fuel assembly, Fig. 11 is a diagram showing the relationship between the position of the floating υ fuel assembly and the number of masks, Fig. 12 is a timing diagram of an echo signal output from the receiver, and Fig. 13 is a schematic configuration diagram of a floating fuel assembly position detection circuit. 106... Fuel assembly, 106A... floating fuel assembly , 109... ultrasonic transducer, 110...
... Reflection plate, 111... Ultrasonic transducer drive mechanism, 112... Ultrasonic transducer position detection circuit, 113... Pulsar, 114... Resino?
-1115... Keto circuit, 116... Timing circuit, 117... Peak value detection circuit, 118...
Floating fuel assembly position detection circuit, 119... Level correction circuit, 120... Display mechanism. Applicant's representative Patent attorney Takehiko Suzue Figure 4 Figure 5 Figure 1 0.5 Echo Eμ/Eβ5

Claims (2)

[Claims] (1) An ultrasonic transducer, a reflector that is placed between the ultrasonic transducer and the object to be measured and that reflects the ultrasonic waves emitted from the ultrasonic transducer, and a reflector that reflects the ultrasonic waves emitted from the ultrasonic transducer; an ultrasonic transducer drive mechanism for rotating the ultrasonic transducer; an ultrasonic transshub position detection circuit for detecting the rotation angle of the ultrasonic transducer; a pulser for outputting a pulser signal to the ultrasonic transducer; and the ultrasonic transducer. a receiver that inputs and amplifies the echo signal detected by the receiver, a gate circuit that opens and closes the path of the echo signal from this receiver, and a circuit that outputs a full pulse trigger signal to the pulser and detects the position of the ultrasonic transformer/user. a timing circuit that sets a dart time corresponding to the transducer position detected by the circuit and outputs a trigger signal to the dart circuit; and a peak value detection circuit that detects the peak value of the echo signal that has passed through the r-) circuit. an obstacle position detection circuit that detects the position of the obstacle on the measurement object from the waveform of the echo signal from the dirt circuit;
a level correction circuit that corrects the peak value detected by the peak value detection circuit based on data corresponding to the obstacle position detected by the obstacle position detection circuit; and a detection signal of the ultrasonic transducer position detection circuit. and a display mechanism that processes and displays signals from the level correction circuit. (2) The obstacle position detection circuit includes a first memory circuit that stores the echo signal (eo) when there is no obstacle, and a second memory circuit that stores the echo signal (e) from the dirt circuit. and the echo signal (,) stored in the second storage circuit is converted into the echo signal (e, ) stored in the first storage circuit.
) and the division result of this division circuit is 0.
．． Ultrasonic fluoroscopy according to claim 1, characterized in that it is comprised of a comparison circuit that compares whether or not it is 7 or less, and a counter that calculates the number of echo signals that are 0.7 or less. Device.