JPH06347363A - Sound detector installation structure - Google Patents

Abstract

(57) [Abstract] [Purpose] To reduce as much as possible the sound attenuation due to the structural material of the steam generator from the sound source to the sound detection sensor. [Structure] An acoustic detection sensor 12 is attached to one end of a waveguide rod 11 for transmitting an acoustic wave, and the waveguide rod 11 penetrates a main body body 1 having a large acoustic damping effect, in which a plurality of heat transfer tubes and a shroud 2 are housed, The other end of the rod 11 is directly fixed to the shroud 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an acoustic detector for detecting a water leak into a liquid metal due to damage of a heat transfer tube of a steam generator used in a liquid metal cooling type fast breeder reactor, for example. The present invention relates to the installation structure of an acoustic detector for installation in a vessel.

[0002]

2. Description of the Related Art A steam generator of a fast breeder reactor is a heat exchanger that heats water with liquid metal such as liquid metal sodium used as a coolant to obtain steam. The configuration of this steam generator will be described with reference to FIG. 7 by taking a helical coil steam generator using a spiral heat transfer tube as an example.

As shown in FIG. 7, in the steam generator, a shroud 2 that forms a liquid metal flow path between the main body 1 and the main body 1 is concentrically provided. An annulus portion is formed between the shroud 1 and the shroud 2. In the shroud 2, an inner cylinder 3 for forming a flow path of the liquid metal is similarly arranged in a concentric shaft shape, and between the shroud 2 and the inner cylinder 3 is composed of a plurality of spiral heat transfer tubes. The tube bundle part 4 is installed.

A water supply tube plate 5 and a water supply inlet nozzle 6 are provided on the lower part of the main body cylinder 1, and a steam tube plate 7 is provided on the upper part of the main body cylinder 1.
And a steam outlet nozzle 8 is provided. Further, a liquid metal inlet nozzle 9 is provided on the top of the main body 1, and a liquid metal outlet nozzle 10 is provided on the bottom of the main body 1.

In the steam generator constructed as described above, water flows in from the water supply inlet nozzle 6 and is distributed to the heat transfer tubes after the water supply tube plate 5 and ascends in the heat transfer tubes to form liquid metal in the tube bundle portion 4. The heat is exchanged and becomes steam, which reaches the steam outlet nozzle 8 through the steam tube sheet 7.

On the other hand, the liquid metal flows from the inlet nozzle 9 and exchanges heat with the water in the heat transfer tubes of the tube bundle portion 4 while flowing down the annulus-shaped flow path formed by the shroud 2 and the inner cylinder 3, and the outlet nozzle. Outflow from 10. The annulus portion formed between the main body 1 and the shroud 2 is a liquid metal retention portion.

The configuration of the steam generator described above is a helical coil steam generator.
Even in a straight-tube steam generator that uses a straight tube as a heat transfer tube, a shroud is provided inside the main body cylinder, liquid metal flows inside the shroud, and there is a liquid metal retention area between the shroud and the main body cylinder. The points are the same.

In the steam generator described above, if the heat transfer tube is damaged, water or steam in the heat transfer tube will flow into the liquid metal, causing a chemical reaction with the liquid metal.
In this accident, the pressure in the system rises due to the generation of hydrogen due to a chemical reaction, and the damage propagates to other heat transfer tubes, expanding the accident.In general, therefore, a water leak due to damage to the heat transfer tube quickly occurs in the steam generator. A water leak detection device that detects
Facilities are installed to discharge reaction products and hydrogen generated by chemical reactions out of the system.

As one of the above-mentioned water leak detecting devices, there is an acoustic detector for detecting water leak by the sound generated when water or steam is jetted into the liquid metal from the damaged portion of the heat transfer tube. The installation structure of this acoustic detector on the steam generator will be described with reference to FIG.

The water leak is detected by acoustic detection by measuring the sound produced by the water leak with an acoustic sensor and processing the measurement result with a signal. The heat-resistant temperature of the acoustic detection sensor is the operating temperature of the steam generator ( Since it is lower than about 300 ° C), a rod (hereinafter referred to as a waveguide rod) 11 for transmitting acoustic waves is fixedly installed on the main body 1 by welding as shown in FIG. An acoustic detection sensor 12 is attached to the tip of the waveguide rod 11.

[0011]

However, in the acoustic detector installed as described above, a large number of heat transfer tubes of the tube bundle portion 4 are provided between the sound source, that is, the damaged portion of the heat transfer tube and the sound detection sensor 12. Since there are structural materials such as the shroud 2 and the main body 1, the sound is attenuated by the time the sound detection sensor 12 is reached, and it is difficult to secure a sufficient SN ratio for detection.

The present invention has been made in consideration of the above-mentioned circumstances, and provides an installation structure of an acoustic detector for reducing acoustic attenuation by a structural material of a steam generator from an acoustic source to an acoustic detection sensor as much as possible. The purpose is to

[0013]

In order to solve the above-mentioned problems, according to claim 1 of the present invention, an acoustic detection sensor is attached to one end of a waveguide rod for transmitting an acoustic wave, and the waveguide rod has a plurality of waveguides. It is characterized in that it penetrates through a main body cylinder having a large acoustic damping effect that accommodates a heat pipe and a shroud, and the other end of the waveguide rod is directly fixed to the shroud.

According to a second aspect of the present invention, the waveguide rod of the first aspect is divided into a portion shorter than a gap between the shroud and the body barrel and an extension portion extending to the outside of the body barrel.
It is characterized by joining these. Further, the invention of claim 3 is characterized in that the waveguide rod of claim 1 is installed so as to penetrate the shroud.

[0015]

In the first aspect of the present invention having the above-mentioned structure, the waveguide rod to which the acoustic detecting sensor is attached penetrates the main body cylinder having a large acoustic damping effect and is directly fixed to the shroud. The sound produced by the water leak can be transmitted to the sound detection sensor while suppressing the attenuation caused by the structural material of the steam generator. Therefore, it is possible to improve the accuracy of the sound detection and to improve the reliability of the sound detector, such as the detection of a smaller water leak.

According to a second aspect of the present invention, the waveguide rod of the first aspect is divided into a portion shorter than the gap between the shroud and the body barrel and an extension portion extending to the outside of the body barrel, and these are joined together. Therefore, the workability of welding the waveguide rod and the shroud is improved. Further, in claim 3,
Since the waveguide rod according to the first aspect is installed so as to penetrate the shroud, attenuation of sound in the shroud can be eliminated.

[0017]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows the installation structure of an acoustic detector according to the first embodiment of the present invention. Note that the same or corresponding portions as in the conventional case will be described using the same reference numerals as those in FIGS. 7 and 8.

In FIG. 1, an acoustic detection sensor 12 is attached to one end of a waveguide rod 11 for transmitting an acoustic wave, and the waveguide rod 11 penetrates through a through hole 1a of a main body 1 having a large acoustic attenuation effect. The other end of is directly joined and fixed to the shroud 2 by welding. The main body 1 and the waveguide rod 11 are joined via an expansion joint 13.

Next, the operation of this embodiment will be described. In the conventional example, the sound reaching the shroud 2 is transmitted to the main body 1 via the liquid metal between the main body 1 and the shroud 2, and the sound is further transmitted via the waveguide rod 11 to the acoustic detection sensor 12.
On the other hand, in this embodiment, since the sound reaching the shroud 2 can be directly transmitted from the shroud 2 to the waveguide rod 11, the liquid metal between the body barrel 1 and the shroud 2 or the body barrel 1 can be transmitted. It is possible to eliminate the attenuation of the sound due to, and to transmit the sound with less attenuation to the sound detection sensor 12.

FIG. 2 shows a modification of the first embodiment,
In this modification, the sleeve mechanism 1 is used instead of the expansion joint 13.
4, the waveguide rod 11 and the main body 1 are joined together.
In this modification, the same effect as that of the first embodiment can be obtained.

FIG. 3 shows the installation structure of the acoustic detector according to the second embodiment of the present invention. The same parts as those in the first embodiment will be described with the same reference numerals. The second embodiment is made in consideration of the manufacturability of a steam generator, and a waveguide rod 15 having a length shorter than the gap between the main body 1 and the shroud 2 is directly joined and fixed to the shroud 2 by welding. A waveguide rod 16 for extension for penetrating the body barrel 1 is coupled to a female screw formed on the waveguide rod 15 with a male screw 17, and one waveguide rod 1
The main body 1 and the waveguide rod 11 are joined to each other through the extension waveguide rod 16 and the expansion joint 13.

Next, the operation of this embodiment will be described.
With respect to the performance related to sound detection during water leak, the waveguide rod 1 can be used when manufacturing a steam generator without impairing the effects of the first embodiment.
5 can be joined and fixed to the shroud 2 by welding in advance, and the shroud 2 with the waveguide rod 15 can be inserted into the main body 1. Therefore, the workability of welding the waveguide rod 15 and the shroud 2 is improved, and Since the through hole 1a of the main body 1 does not need to be large for welding the shroud 2 and the waveguide rod 15, the productivity of the steam generator is improved.

FIG. 4 shows a modification of the second embodiment. In this modification, a short waveguide rod 15 and an extension waveguide rod 16 are butt-welded by diffusion welding. The same effect as the second embodiment can be obtained. Although the expansion joint 13 is used in FIGS. 3 and 4, a sleeve mechanism as shown in FIG. 2 may be used. The rest of the configuration and operation are the same as in the first embodiment, so a description thereof will be omitted.

FIG. 5 shows the installation structure of the acoustic detector according to the third embodiment of the present invention. The same parts as those in the first embodiment will be described with the same reference numerals. In the third embodiment, the notch 19 is formed in the shroud 2, the tip of the waveguide rod 11 is directly arranged in the notch 19, and the waveguide rod 11 and the shroud 2 are joined together via the expansion joint 20. is there. Here, the expansion joint 20 is the waveguide rod 11 in the first embodiment.
It may be replaced with a sleeve mechanism such as that employed for the penetrating portion 1a of the main body 1.

Next, the operation of this embodiment will be described.
In the third embodiment, since the waveguide rod 11 is installed so as to penetrate the shroud 2, sound attenuation in the shroud 2 can be further eliminated as compared with the first embodiment, and sound with a smaller attenuation can be detected by the sound detecting sensor 12. It becomes possible to tell. Also,
Since the waveguide rod 11 is not directly joined to the shroud 2, the difference in thermal expansion between the shroud 2 and the main body 1 is easily absorbed, and the reliability of the steam generator is improved.

FIG. 6 shows a modification of the third embodiment. In this modification, the tip shape of the waveguide rod 11 on the shroud 2 side is made to match the inner surface shape of the shroud 2 and the area is increased. The enlarged portion 21 is integrally formed. As a result, it is possible to increase the area for receiving the sound and reduce the influence of the installation of the waveguide rod 11 on the flow of the liquid metal in the shroud 2.

In each of the above embodiments, the helical coil type steam generator has been described as an example. However, the present invention is not limited to the straight pipe type steam generator, but also performs acoustic detection in the tube bundle for abnormality diagnosis. It is also applicable to the heat exchanger of.

[0028]

As described above, according to the first aspect of the present invention, the waveguide rod to which the acoustic detection sensor is attached penetrates the main body cylinder having a large acoustic attenuation effect and is directly fixed to the shroud. It is possible to transmit the sound due to water leak caused by the breakage of the heat transfer tube to the sound detecting sensor while suppressing the attenuation due to the structural material of the steam generator to be small. Therefore, it is possible to improve the accuracy of the sound detection and to improve the reliability of the sound detector, such as the detection of a smaller water leak. Therefore, when applied to a fast breeder reactor plant, its reliability can be improved.

According to a second aspect of the present invention, the waveguide rod of the first aspect is divided into a portion shorter than the gap between the shroud and the body barrel and an extension portion extending to the outside of the body barrel, and these are joined together. Therefore, the workability of welding the waveguide rod and the shroud is improved.

Further, according to the third aspect, since the waveguide rod according to the first aspect is installed so as to penetrate the shroud, attenuation of sound in the shroud can be eliminated, and the accuracy of sound detection can be further improved.

[Brief description of drawings]

FIG. 1 is an enlarged sectional view showing a first embodiment of the installation structure of an acoustic detector according to the present invention.

FIG. 2 is an enlarged cross-sectional view showing a modified example of the embodiment of FIG.

FIG. 3 is an enlarged sectional view showing a second embodiment of the installation structure of the acoustic detector according to the present invention.

FIG. 4 is an enlarged cross-sectional view showing a modified example of the embodiment of FIG.

FIG. 5 is an enlarged sectional view showing a third embodiment of the installation structure of the acoustic detector according to the present invention.

6 is an enlarged cross-sectional view showing a modified example of the embodiment of FIG.

FIG. 7 is a sectional view showing the structure of a steam generator in which an acoustic detector is installed.

FIG. 8 is an enlarged cross-sectional view showing the installation structure of a conventional acoustic detector.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 main body 2 shroud 3 inner cylinder 4 tube bundle part 11 waveguide rod 12 acoustic detection sensor 13 expansion joint 14 sleeve mechanism 15 short waveguide rod 16 extension waveguide rod 17 male screw 19 notch 20 expansion joint

Claims (3)

[Claims] 1. An acoustic detection sensor is attached to one end of a waveguide rod for transmitting an acoustic wave, and the waveguide rod penetrates a main body cylinder having a large acoustic damping effect, which houses a plurality of heat transfer tubes and a shroud, and the waveguide rod. The acoustic detector installation structure in which the other end of the above is directly fixed to the shroud. 2. The waveguide rod is divided into a portion shorter than a gap between the shroud and the body barrel and an extension portion extending to the outside of the body barrel, and these are joined together. The installation structure of the acoustic detector according to claim 1. 3. The acoustic detector installation structure according to claim 1, wherein the waveguide rod is installed so as to penetrate the shroud.