JP2003028979A - Water leak detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve reliability in the detection of water leak by enhancing the sensitivity and the signal-to-noise ratio of a water leak detector, mounted on the steam generator of a fast breeder reactor. SOLUTION: This detector is provided with a laser oscillator 15, a beam splitter 16 for halving a laser beam, a light detector 22 that passes each of the halved laser beam through each of two optical fibers 17 and 19 and makes the output light from the fiber remerge to measure the light intensity after mergence, a means of transmitting sound wave outside an instrumentation pipe 18 to the optical fiber 19 inside it through a sound wave propagation liquid 21 by inserting one (19) of the optical fibers, together with the instrumentation pipe 18 protecting the fiber 19 against sodium 2 inside a steam generator into its body 1 and a signal processing device 13, that measures the intensity of the sound wave imparted to the optical fiber 19 from the changes in the light intensity during the time passage after the mergence. The detector is equipped with an alarm system, that issues an alarm according to the processed result of the signal processing device 13. The detector detects the sound of leakage, when water leaks and determines the leak from the loudness of the sound.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water leak detector, and more particularly to a technique suitable for detecting water leak from a heat transfer tube in a fast breeder reactor steam generator.

[0002]

2. Description of the Related Art FIG. 5 shows a steam generator of a fast breeder reactor.
Sodium (hereinafter referred to as N
Display as a. 2), and water 5 is flown into the heat transfer tube 7 to exchange heat, and high-pressure steam 6 is generated. Should the heat transfer tube 7 break during operation, the high-pressure water in the heat transfer tube 7 leaks into Na, causing a Na / water reaction accident.

Therefore, in the conventional steam generator, a plurality of waveguides 36 and the acoustic detector 10 are attached to the outer wall of the steam generator body 1 as shown in FIG. Measures have been taken to detect leakage by detecting it.

The above-mentioned leakage sound is a sound generated when hydrogen bubbles 9 are generated due to the reaction of water and Na. In the related art, this leakage sound is discriminated from other noise signals by the signal processing device 11 to obtain a leakage sound signal. When the value exceeds a certain value, it is determined that a water leak has occurred, and the alarm generator 12 gives a leak warning. Further, the water leakage position 8 is determined from the output comparison (arrival time difference) of the plurality of acoustic detectors 10.

[0005]

In the above-mentioned water leakage detector, since there are innumerable acoustic paths from the sound source to the detector, the acoustic signal has a large noise signal level, and the signal for extracting the leakage signal is large. It took a long processing time. Also,
Since the S / N is small, improvement in reliability in identifying the leakage position is desired. Waveguide and waveguide to signal processor 1
If an electric circuit is used in the signal path up to 1, the sound will be severely attenuated when the sound wave is transmitted through the waveguide, and the surrounding electric noise will easily enter the electric circuit, resulting in a small S / N and reliable water leakage. Detection cannot be easily achieved.

An object of the present invention is to achieve reliable water leak detection.

[0007]

The first means is to equip the inside of an instrumentation tube inserted into the body of a steam generator with a detection means for detecting an event that occurs when water leaks. It is a water leak detector equipped with a signal processing device that determines the presence or absence of water leaks based on the detection results. It can detect water leaks quickly and reliably by detecting deeply and with high sensitivity.

The second means is a laser oscillator, a means for dividing the laser light outputted from the laser oscillator into at least two, a plurality of optical fibers for passing the respective laser light divided into at least two, and the plurality of optical fibers. An instrumentation tube containing a part of the number of optical fibers, a photodetector for outputting an electric signal proportional to the total light intensity of the exit light of the plurality of optical fibers, and based on the output signal of the photodetector. A water leak detector comprising: a signal processing device for determining a signal corresponding to the intensity of a sound wave applied to an optical fiber in the instrumentation pipe, and determining a leak based on the signal corresponding to the intensity of the sound wave. .

In such a water leak detector, an instrumentation tube is inserted inside the steam generator, and a sound wave (pressure) generated at the time of water leakage is applied to an optical fiber in the instrumentation tube, at which time the optical characteristics of the optical fiber ( For example, the refractive index) changes, and the phase of light passing therethrough is shifted. In order to emphasize the phase shift, the exit lights of a plurality of optical fibers are merged and replaced with an electric signal for the first time by a photodetector. Therefore, the optical fiber is used as a leaky acoustic sensor and a transmission line for sensing information, and the optical fiber does not pick up noise of an external electric signal. Therefore, the S / N ratio is improved. A signal corresponding to the intensity of the sound wave generated at the time of water leakage is obtained from the output electric signal of the photodetector, and a signal processing device determines whether or not there is a leakage based on comparison with a reference value for leakage determination.

A third means is a laser oscillator, a means for dividing the laser light outputted from the laser oscillator into at least two, a plurality of optical fibers for passing the respective divided laser light, and a plurality of the plurality of optical fibers. An instrumentation tube in which a part of the number of optical fibers is inserted, and a plurality of acoustic wave propagators incorporated in the instrumentation tube so as to make acoustic contact with the optical fibers contained in the instrumentation tube and having mutually different resonance frequencies. A photodetector that outputs an electric signal proportional to the total light intensity of the exit light of the plurality of optical fibers; and a photodetector that is provided to receive the output signal of the photodetector and that corresponds to each resonance frequency. A plurality of band pass filters having transmission frequencies set, a switcher for selecting an output from each of the band pass filters, and a switch based on the output from the selected band pass filter. Then, a signal corresponding to the intensity of the sound wave applied to the optical fiber in the instrumentation tube is obtained for the output from the plurality of band pass filters, and the output of the band pass filter showing the strongest sound wave intensity is output. It is a water leak detector provided with a signal processing device which determines the leak position by indexing the acoustic wave propagator having a resonance frequency corresponding to the transmission frequency.

Even with such a water leakage detector, the S / N ratio at the time of water leakage detection is improved as in the second means. In addition, the leak location can be determined.

In either case, an instrumentation tube containing a sensor part of an optical fiber is inserted inside the steam generator, and the sound wave generated when water leaks can be detected directly as compared with the case where a waveguide is used. An optical fiber that can withstand high temperature and electrical noise is used as the sensor. The principle of adding the information of the sound wave generated at the time of water leakage to the light inside the optical fiber is that when the sound wave (pressure) is applied to the optical fiber, the optical characteristics (for example, the refractive index) change and the phase of the light passing therethrough shifts. We are using.

The fourth means is an instrumentation tube, an exciting coil arranged in the instrumentation tube to generate a magnetic field, a detection coil installed in the instrumentation tube to detect a change in the magnetic field, and the detection coil. Comparing the effective value with the value of the predetermined leak determination signal by a calculator that calculates the effective value based on the detection result of, and determines that water leakage is present when the effective value is greater than the value of the leak determination signal. It is a water leak detector equipped with a determining device that does.

In such a water leakage detector, the exciting coil and the detecting coil are put in an instrumentation tube, and the exciting coil and the detecting coil are protected by the instrumentation tube and inserted into the steam generator body, Bubbles generated at the time of leakage can be directly detected electromagnetically. A magnetic coil is used as the detecting means. That is, the distortion of the induced current (eddy current) generated when the bubbles pass through the conductive fluid in the steam generator body to which the magnetic field is applied from the exciting coil is detected by the detection coil, which is a magnetic coil, to prevent water leakage. Can be detected.

[0015]

Embodiments of the present invention will be described in detail below. FIG. 1 shows the structure of a water leakage detector according to the first embodiment of the present invention. The water leak detector is applied to the steam generator of a fast breeder reactor. In the steam generator, the water supply header 3 and the steam header 4 are connected by a plurality of heat transfer pipes 7,
Is surrounded by a steam generator body 1. In such a steam generator, Na heated in the steam generator barrel 1
2 in and out. Then, the water supplied to the water supply header 3 enters the heat transfer tube 7 and reaches the steam header 4, and at that time point, the water passes through the heat transfer tube 7 and flows into the N inside the steam generator body 1.
It receives heat from a2 and becomes steam.

The water leak detector of this embodiment is a laser oscillator 1.
5, a beam splitter 16 that divides the laser beam output from the laser oscillator 15 into two, a reference optical fiber 17 through which one of the two divided laser beams enters and passes, and the other divided two laser beam. A photodetector 22 which outputs an electric signal proportional to the total light intensity obtained by combining the sensor optical fiber 19 which is incident and passed through, and the exit light emitted from both the reference optical fiber 17 and the sensor optical fiber 19. And a signal processing device 13 that receives the output signal of the photodetector 22 to determine water leakage, and an alarm generator 14 that issues an alarm when it is determined that there is water leakage based on the determination result.

Of these, the sensor optical fiber 19 is directly inserted into the steam generator barrel 1 via the instrumentation tube 18. This instrumentation tube 18 isolates the sensor optical fiber 19 from Na2 in the steam generator barrel 1 to avoid contact between them. A sensor support fitting 20 is attached inside the instrumentation tube 18, and a sensor optical fiber 19 is wound around the sensor support fitting 20. Further, in order to transmit the acoustic signal reaching the outer surface of the instrumentation pipe 18 to the sensor optical fiber 19 inside, a sound wave propagation liquid 21 is enclosed inside the instrumentation pipe 18. Sound wave propagating liquid 21
For example, liquid mercury that is safe without reacting with Na2 and that easily contacts the inner wall surface of the instrumentation tube 18 and the sensor optical fiber 19 is used.

The laser light from the laser oscillator 15 is divided into two by the beam splitter 16, one is sent to the sensor optical fiber 19 and the other is sent to the reference optical fiber 17. Both lights join again and enter the photodetector 22. The photodetector 22 outputs an electric signal proportional to the total of the two lights.

FIG. 6 shows the output signal of each section in time series.
In general, when the laser light passes through the optical fiber and there is a temperature change or a pressure is applied, the optical refractive index or the reflectance inside the optical fiber changes, and the phases shift.
Normally, the temperature of sodium (Na2) in the steam generator changes with time, so that the light passing through the sensor optical fiber 19 is out of phase with the light passing through the reference optical fiber 17.

Therefore, the output signal of the photodetector 22 is as shown in FIG.
It appears as a signal having a certain width (interference width) as shown in (b). However, when there is no sound wave reaching the sensor optical fiber 19, the phase shift between the light passing through the sensor optical fiber 19 and the light passing through the reference optical fiber 17 does not change with time, so that the output width of the photodetector 22 changes with time. Does not change. However, when a sound wave arrives at the sensor optical fiber 19, the phase shift between the two lights changes with time, so that the output width of the electrical signal from the photodetector 22 changes. That is, the output signal of the photodetector 22 appears as a signal that changes according to the temporal change of the sound wave intensity.

In this embodiment, the output signal of the photodetector 22 is inputted to the signal processing device 13 as an electric signal, the signal level is judged, and then an alarm signal is sent to the alarm generator 14. In order to increase the sensitivity of the phase change due to the leakage sound, it is preferable that the sensor optical fiber 19 is not linear, but is bent so that a large change in the optical characteristic of the optical fiber (for example, a change in the refractive index) can be obtained. For this reason, in this embodiment, the sensor optical fiber 19 is incorporated in the instrumentation pipe 18 in a state of being wound around the fiber support fitting 20.

FIG. 2 shows the configuration of the signal processing device 13 in the above embodiment. This signal processing device is a filter 37, R
It is composed of an MS calculator 23, a determiner 24, and a leak determination signal generator 25. The electrical output signal from the photodetector 22 first enters the filter 37 where only acoustic signals are extracted (see FIG. 6). As described above, the optical characteristics of the sensor optical fiber 19 also change depending on the temperature change of the optical fiber. Therefore, when light passes through the same optical fiber, the phase also changes due to temperature change. However, the rate of change of temperature is slower than the change of sound and is at most 50.
It is about Hz. On the other hand, the sound has a frequency of 20 kHz or more and can be sufficiently separated in terms of frequency.

Therefore, in this embodiment, a high-pass filter having a cutoff frequency of about 20 kHz is used as the filter 37. The output signal of the filter 37 shown in FIG. 6C, which has exited the filter 37, enters the RMS calculator 23 in the subsequent stage, where the effective value is calculated. Next, the output signal of the RMS calculator 23 of FIG. 6 (d), which shows this effective value, enters the latter-stage deciding unit 24 and is compared with a predetermined leak deciding signal. The leakage determination signal is provided by the leakage determination signal generator 25. If the above effective value is greater than the specified value,
When it is judged that a leak has occurred, an alarm signal is given to the alarm generator 14 in the subsequent stage, and the alarm generator 14 operates to issue an alarm.

FIG. 3 shows the configuration of another embodiment relating to the sensor optical fiber 19. Also in this embodiment, the sensor optical fiber 19 is incorporated in the instrumentation pipe 18 and directly inserted into the steam generator. This instrumentation tube 18
Isolates the sensor optical fiber 19 from Na2 in the steam generator barrel 1 to avoid contact between them. A plurality of sound wave propagators 27 are in contact with the inner surface of the instrumentation tube 18, and a light converter 28 is incorporated therein as a part of the sound wave propagator 27. The acoustic propagator 27 incorporates acoustic characteristics, for example, different acoustic frequencies. In the present embodiment, the resonance frequencies of the acoustic propagators 27 are changed by changing the radial thickness of the acoustic propagators 27.

The light transducer 28 is provided with a protrusion inside the sound wave propagator 27, and the sensor optical fiber 1 is provided inside the protrusion.
9 is installed in contact with. The projections of the light converter 28 have a structure in which they travel to the center alternately in the axial direction, and the inner sensor optical fiber 19 is bent into an S shape. As a result, even a slight sound wave reaching the sensor optical fiber 19 has a large effect of the change in the refractive index of the optical fiber.

The wall of the instrumentation tube 18, the sound wave propagator 27 and the light converter 28 are acoustically connected to each other, and serve to transmit the sound wave reaching the outer surface of the instrumentation tube 18 to the sensor optical fiber 19 in the central portion. .

As described above, each of the sound wave propagators 27 has a resonance frequency based on the wall thickness, and the sound wave passing therethrough is selectively amplified in the vicinity of the resonance frequency.
Ar gas 31 is enclosed inside the sound wave instrumentation tube 18.

In this embodiment, the leakage sound generated outside the instrumentation pipe 18 is transmitted to the sensor optical fiber 19 through the nearest sound wave propagator 27. The acoustic signal locally changes the refractive index or reflectance of the sensor optical fiber 19, and the phase of the light exiting the sensor optical fiber 19 is shifted. The means for interfering the light emitted from the sensor optical fiber 19 with the reference optical fiber to perform signal processing and issue an alarm is the same as in the embodiment of FIG.

When the configuration of FIG. 3 is adopted, the acoustic wave near the resonance frequency is selectively amplified when the acoustic wave passes through the acoustic wave propagator 27. Therefore, if the output signal of the photodetector 22 is frequency-analyzed in FIG. The sound wave propagator 27 through which the sound wave has passed, that is, the sound wave propagator 27 closest to the leak point, can be known as follows.

FIG. 4 shows the structure of the signal processing apparatus in the embodiment adopting the structure of FIG. Of the configurations of the present signal processing device, the filter 37, the RMS calculator 23, and the determiner 2
4 and the leakage determination signal generator 25 have the same configuration as the embodiment of FIG. The signal processing apparatus is configured such that a band pass filter 38, an electronic switching device 39, an RMS calculator 32, a judging device 34, and a leak position indicator 35 are further added.

The added means operate as follows. The output signal from the photodetector 22 enters a plurality of bandpass filters 38. The transmission frequency of each band pass filter 38 corresponds to the resonance frequency of the sound wave propagation member 27 described in the embodiment of FIG. As a result, the signal from the photodetector 22 is separated by the bandpass filter 38 into the acoustic signals from the respective acoustic wave propagators 27. The output signal of each bandpass filter 38 is selected by the switching operation by the electronic switching unit 39, enters the RMS calculator 32, and each effective value of the output signal of each bandpass filter 38 is obtained. Next, each effective value calculated by the RMS calculator 32 enters the judgment device 34 in the subsequent stage together with the information of the switching destination of the electronic switch 39, and the maximum effective value is selected, and the transmission frequency of the band pass filter 38 which gives it is given. That is, the position of the sound wave propagator 27 through which the maximum sound wave is transmitted is determined.

The finally determined position of the sound wave propagating element 27 is sent as a water leak position signal to the leak position indicator 35 in the subsequent stage, and the water leak position is displayed at the same time as the leak alarm of the alarm generator 14.

As described above, in the embodiment of the present invention, since the instrumentation tube 18 containing the optical fiber is directly inserted into the steam generator barrel 1, the S / N ratio is improved and the inside of the steam generator barrel 1 is improved. It can detect the water leak sound of.

Further, since the internal light of the optical fiber is not easily affected by electrical noise, the S / N ratio is further improved, and no large-scale signal processing is required for extracting the acoustic signal, and the detection time can be shortened. .

Further, in the embodiment shown in FIGS. 3 and 4, the reliability in identifying the water leakage position is improved.

As described above, in the method of detecting water leakage by placing sound information on light, not only water leakage but also water leakage-based sound is detected through innumerable paths.
There is a demand for water leak detection that does not rely on the detection of sound information.

When water leaks from the steam generator, sound is generated by the reaction between the water 5 leaking from the heat transfer tube 7 in the steam generator barrel 1 and Na2 in the steam generator barrel 1, but in addition, hydrogen bubbles 9 Also occurs. Focusing on the generation of the hydrogen bubbles 9, the following examples were proposed.

According to the idea, an exciting coil and a detecting coil are put in an instrumentation tube, which is protected by the instrumentation tube and inserted into the steam generator body, and hydrogen bubbles generated at the time of water leakage are electromagnetically directly Take measures to detect. A magnetic coil is used as the detecting means. That is, the distortion of the induced current (eddy current) generated when the hydrogen bubbles pass through the conductive fluid (Na2) in the steam generator body to which the magnetic field is applied from the exciting coil is detected by the detection coil which is the magnetic coil. Use means.

In the following, the water leakage is detected by detecting the distortion of the induced current (eddy current) generated by the movement of the hydrogen bubbles 9 generated at the water leakage position 8 during the water leakage in the steam generator body 1. An example will be described. The structure of the steam generator is the same as in the embodiment of FIG. 7 to 9 show the structure of an embodiment of the water leakage detector. In this embodiment, an exciting coil 114, an exciting power source 115 connected to the exciting coil 114, a detecting coil 113, and an ammeter 11 connected to the detecting coil 113.
8 and a signal processing device 122 connected to receive the output of the ammeter 118.

The exciting coil 114 and the detecting coil 113 are wound around an insulating material 117 and are placed inside the instrumentation tube 116.
Installed every time, the instrumentation tube 116 has Na2 and the exciting coil 11
4, contact with the detection coil 113 and the insulating material 117 is prevented. The instrumentation pipe 116 is inserted into the steam generator barrel 1 as shown in FIG. 1 and is mounted on the steam generator.

For the exciting coil 114, one conductive wire is used as the insulating material 1.
An excitation power supply (AC power supply) 115 is attached to both ends of the coil by spreading it on the outer surface of 17. A single conducting wire is wound as a detection coil 113 on the surface of the insulating material near the wound exciting coil 114, and both ends thereof are connected so that an ammeter 118 outside the instrumentation tube 116 can be input.

The output of the ammeter 118 enters the signal processing device 122 in the subsequent stage, where the water leak and the leak position are judged. In this embodiment, the detection coil 1
A magnetic field created by an exciting current and a part B of the magnetic field created by an induced current I generated when Na2, which is a conductive fluid, crosses the magnetic field 13 (hereinafter referred to as magnetic field B). When a time change of the magnetic field B occurs, a current that cancels the change flows. When the steam generator is operating normally without water leakage, the distribution of the magnetic field B is constant and does not change with time. Therefore, since the magnetic flux that crosses the detection coil 113 does not change with time, no current flows through the detection coil 13.

However, a water leak occurs and the steam generator barrel 1
When a hydrogen bubble 9 is generated inside and the hydrogen bubble 9 passes near the detection coil 113, the hydrogen bubble 9 changes the direction of the induced current I, so that the distribution of the magnetic field B changes like a magnetic field B ′. A current flows through the detection coil 113 so as to cancel this change.

In this embodiment, this current change is detected by the detection coil 1
It is detected by an ammeter 118 which is connected to 13 and incorporated. Further, in this embodiment, the exciting coil 114 and the detecting coil are
A plurality of detection units 121 each composed of a pair of 113 are attached to the insulating material 117 at a plurality of positions in the axial direction, and the magnitude of the current generated in the detection coil 113 at each position can be monitored.

With this configuration, it is possible to identify which detector 121 the hydrogen bubble 9 is generated near, that is, the water leakage occurrence position. Note that, as will be described later, it is also possible to configure a plurality of detection coils with a single conductive wire for multiplex transmission.

FIG. 9 typically shows the configuration of one of the three signal processing devices 122 having the same configuration in the above embodiment. The signal processing device 122 includes an RMS calculator 123, a determiner 119, a leak determination signal generator 124, and an alarm generator 120. The current input from the detection coil 113 is measured by the ammeter 118, and the voltage corresponding to the current is supplied to the RMS calculator 123 as an output signal. The ammeter 118 may be provided with a meter for displaying the current detection value as a result of measurement, and it may be determined from the magnitude of the current detection value whether or not there is a leak by looking at the pointer of the meter.

The output signal of the ammeter 118 enters the RMS calculator 123, where the effective value is calculated. Then, the signal of this effective value is sent from the RMS calculator 123 to the judging device in the subsequent stage.
At 119, the signal is compared with a predetermined leakage determination signal. The leakage determination signal is provided by the leakage determination signal generator 124. When the above-mentioned effective value is larger than the value of the predetermined leakage determination signal, it is determined that leakage has occurred, and the alarm generator 120 in the subsequent stage
To the alarm generator 1
20 gives an alarm.

FIG. 10 shows a configuration of a signal processing device in the case where a plurality of detection coils 113 are constituted by one conductor and the detection signals are multiplexed and transmitted. The case where there are three detection coils will be described below, but the same applies to any number of detection coils 113. The exciting coil 114 has frequency components F1, F2,
It is excited by an AC power supply including F3.

The detection coil 113 is made by winding one conductive wire around the three detecting portions. Capacitances C1, C2 and C3 having different values are attached to the respective detection coils 113 so as to preferentially respond only to the magnetic field components of the above frequencies F1, F2 and F3.

In the present embodiment, the current generated in the detection coil 113 due to the passage of hydrogen bubbles is measured by the ammeter 118, and the voltage corresponding to the current is used as an output signal for the ammeter.
118 feeds three bandpass filters 125. The transmission frequencies of the band pass filters 125 are the pick-up frequencies F1 and F attached to the respective detectors.
2 and F3. The ammeter 118 is not one for each detection coil as in the example of FIG. 9, but one for the three detection coils.

Each output signal of each band pass filter 125 is switched by the electronic switch 126 and the RMS of the subsequent stage is switched.
The arithmetic unit 123 is entered and each effective value is calculated. R
The MS calculator 123 receives the switching position information of the electronic switch 126 and knows which pickup frequency F1, F2, F3 effective value is calculated by the switching position of the electronic switch 126. Each calculated effective value is input from the RMS calculator 123 to the judging device 119 in the subsequent stage together with the above-mentioned switching position information, and the effective value is compared with a predetermined leakage judgment signal.
Here, when the effective value is larger than the predetermined leakage determination signal,
It is determined that a leak has occurred at the position of the target detection unit determined from the switching position information, and an alarm generator 120 in the subsequent stage issues an alarm together with the leak position.

As described above, in each of the embodiments shown in FIGS. 7, 8, 9 and 10, the excitation coil and the AC excitation power source are used for the purpose of excitation. The same function can be obtained by using a permanent magnet instead.

According to each of the embodiments shown in FIGS. 7, 8, 9 and 10, since the instrumentation tube containing each coil is directly inserted into the steam generator barrel, the S / N ratio is improved, There is no need for large-scale signal processing for extracting acoustic signals as in the past,
Detection time can be shortened. Moreover, the reliability of the water leakage position determination is improved.

In either embodiment, the instrumentation tubes 18, 116
The inside is separated from the outside. The instrumentation pipe 18,11
6 is used by being fixed to the upper flange 30 which constitutes the upper wall of the steam generator body 1 with the sensor fixing tap 29.

[0055]

According to the present invention, the characteristic information generated at the time of water leakage can be sensed with a good S / N ratio, so the reliability of water leakage detection is improved.

[Brief description of drawings]

FIG. 1 shows a configuration of a water leakage detector according to an embodiment of the present invention, FIG. 1 (a) is an overall configuration of the water leakage detector, and FIG. 1 (b) is an enlarged sectional view of a portion A of FIG. , (C) is a view showing a cross-sectional view taken along line BB of (b).

FIG. 2 is a diagram showing a configuration of a signal processing device in the embodiment of FIG.

3A and 3B are views showing the inside of an instrumentation pipe according to another embodiment of the present invention, wherein FIG. 3A is a vertical sectional view of the instrumentation pipe, and FIG. 3B is a sectional view taken along the line aa of the instrumentation pipe. Is shown.

FIG. 4 is a diagram showing a configuration of a signal processing device of a water leakage detector using the instrumentation pipe of FIG.

FIG. 5 is a diagram illustrating an overall configuration of a conventional water leakage detector.

FIG. 6 is a diagram showing an output signal of each unit in the embodiment of the present invention.

FIG. 7 is a schematic cross-sectional view of a steam generator in which a water leakage detector based on a change in induced current (eddy current) is inserted according to an embodiment of the present invention.

FIG. 8 is a diagram showing a configuration of a water leakage detector based on a change in induced current (eddy current) according to an embodiment of the present invention.

FIG. 9 is a diagram showing a configuration of a signal processing device in the above embodiment.

FIG. 10 is a diagram showing a modification of the signal processing device of FIG. 9.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Steam generator barrel, 2 ... Sodium, 5 ... Water, 7 ... Heat transfer tube, 8 ... Water leakage position, 9 ... Hydrogen bubble, 10 ... Acoustic detector, 13 ... Signal processing device, 14, 120 ... Alarm generator ,
15 ... Laser oscillator, 16 ... Beam splitter, 17
… Reference optical fiber, 18, 116… Instrumentation tube, 19…
Sensor optical fiber, 20 ... Fiber support bracket, 2
1 ... Sound wave propagation liquid, 22 ... Photodetector, 23, 32, 123
... RMS calculator, 24, 34, 119 ... Judgment device, 25,
124 ... Leakage determination signal generator, 27 ... Sound wave propagator, 28
... Light converter, 31 ... Ar gas, 35 ... Leakage position indicator,
37 ... filter, 38, 125 ... band pass filter,
39, 126 ... Electronic switching device, 113 ... Detection coil, 11
4 ... Exciting coil, 115 ... Excitation power supply, 117 ... Insulating material, 118 ... Ammeter, 122 ... Signal processing device.

Continued front page    (72) Inventor Atsuhiko Kubo             3-1-1 Sachimachi, Hitachi City, Ibaraki Prefecture Stock Association             Hitachi, Ltd. Nuclear Business Division F term (reference) 2G067 AA18 BB16 CC02 DD15 EE08                 2G075 AA07 BA17 CA05 DA10 DA16                       EA01 FA12 FA14 FA16 FB20                       FC03 FD07

Claims (10)

[Claims] 1. An instrumentation tube inserted into the body of a steam generator is equipped with detection means for detecting an event that occurs at the time of water leakage, and the presence or absence of water leakage based on the detection result of the detection means. A water leak detector equipped with a signal processing device for determining whether the water leakage is detected. 2. A laser oscillator, a means for dividing the laser light output from the laser oscillator into at least two, a plurality of optical fibers for passing the respective laser light divided into at least two, and one of the plurality of optical fibers. An instrumentation tube in which the number of parts is inserted, a photodetector that outputs an electric signal proportional to the total light intensity of the exit light of the plurality of optical fibers, and the instrumentation based on the output signal of the photodetector. A water leak detector, comprising: a signal processing device that obtains a signal corresponding to the strength of a sound wave applied to an optical fiber in a pipe, and determines a leak based on the signal corresponding to the strength of the sound wave. 3. A laser oscillator, a means for dividing the laser light outputted from the laser oscillator into at least two, a plurality of optical fibers for passing the respective laser light divided into at least two, and one of the plurality of optical fibers. An instrumentation tube containing a number of parts, a plurality of acoustic wave propagators having different resonance frequencies built into the instrumentation tube so as to make acoustic contact with the optical fiber contained in the instrumentation tube, and A photodetector that outputs an electric signal proportional to the total light intensity of the exit light of the plurality of optical fibers, and a transmission frequency that is provided to receive the output signal of the photodetector and that corresponds to each resonance frequency. A plurality of band pass filters that have been set, a switch that selects the output from each band pass filter, and the instrumentation based on the output from the selected band pass filter. A signal corresponding to the strength of the sound wave applied to the optical fiber inside is obtained for the output from the plurality of band pass filters, and corresponds to the transmission frequency of the band pass filter that outputs the output showing the strongest sound wave strength. And a signal processing device for determining the leakage position by determining the sound wave propagating element having the resonance frequency. 4. The water leak detector according to claim 2, wherein mercury is contained as an acoustic wave propagating liquid in the instrumentation tube in contact with the optical fiber. 5. The water leak detector according to claim 2 or 4, wherein an optical fiber is wound around a fiber support fitting and housed in the instrumentation tube. 6. The water leakage detector according to claim 3, wherein the sound wave propagating element is provided with a projection-shaped optical transducer inside, and the optical transducer is in contact with the optical fiber so as to bend the optical fiber into an S shape. 7. An instrumentation tube, an excitation coil arranged in the instrumentation tube to generate a magnetic field, a detection coil installed in the instrumentation tube to detect a change in the magnetic field, and a detection result by the detection coil. A calculator for calculating an effective value based on the above, and a determiner for comparing the effective value with a value of a predetermined leakage determination signal and determining water leakage when the effective value is larger than the value of the leakage determination signal. And a water leak detector. 8. The water leakage detector according to claim 7, wherein the detection coil and the excitation coil form one set, and the plurality of sets are mounted on a common insulating material and housed in the instrumentation pipe. 9. The detection coil according to claim 7, wherein detection coils having different pickup frequencies are connected in series and provided in an instrumentation pipe, and each pickup frequency is provided between the detection coil and the arithmetic unit. A water leak detector comprising: a plurality of bandpass filters having frequencies set to transmission frequencies in parallel, and a switcher for switching and connecting the plurality of bandpass filters to the arithmetic unit. 10. The pipe according to any one of claims 2 to 9, wherein the instrumentation pipe is inserted into the body of the steam generator and mounted on the steam generator, and the inside of the heat transfer pipe of the steam generator is provided. A water leak detector in which water is passed through the tube and sodium is passed through the shell, and the instrumentation tube is immersed in the sodium.