JP5574788B2 - Conductive liquid leak detection line - Google Patents

Description

The present invention, for example, in a facility for handling liquid metal sodium as a conductive liquid such as a fast breeder reactor, a line for detecting that the conductive liquid has leaked or infiltrated from a pipe for sending the conductive liquid or a container for storing the same. In particular, the present invention relates to a conductive liquid leak detection line that is excellent in responsiveness to a conductive liquid to be detected and that does not malfunction due to the ingress of water droplets or the like.

   Conventionally, in pipes that pass liquid metal sodium such as fast breeder reactors and containers that store them, conductive liquid leak detection lines are attached to these pipes and containers to prevent leakage of liquid metal sodium in the event of an emergency. I try to detect it. When liquid metal sodium leaks from a pipe or container, the leaked liquid metal sodium electrically detects that the conductive liquid detection line and the pipe or container are electrically short-circuited or conducted. It is a mechanism for detecting leaks. We monitor leaks from the bellows of valves that contain liquid metal sodium and leaks from equipment and piping. Such a conductive liquid leak detection line is employed and installed in equipment for a fast breeder reactor.

  As a conventional conductive liquid leak detection line, a ceramic insulator type conductive liquid leak detection line is known. An example of this conventional ceramic insulator type conductive liquid leakage detection line and its measurement circuit is shown in FIG. The ceramic insulator type conductive liquid leakage detection line of this conventional example uses a nickel wire having a diameter of about φ1.2 as the conductive wire 4, and is simple by extrapolating a ceramic insulator 10 having a diameter of about φ4.2 to the conductive wire 4. Structure. When the liquid metal sodium leaked from the pipe 1 penetrates into the gap between the ceramic insulators 10 and comes into contact with the conductive wire 4, the conductive wire 4 and the pipe 1 are short-circuited and are electrically detected. Thus, leakage of liquid metal sodium is detected. The detection unit 6 includes, for example, a test switch 7, a power source 8 that supplies a weak current to the conductive wire 4, and an ammeter 9 that electrically detects a short circuit and conduction between the conductive wire 4 and the pipe 1. The switch 7 is periodically closed to confirm that the conductive wire 4 is not disconnected, and remains open in a normal leakage detection state. Such a conductive liquid leak detection line is applied to detection of a wide range of parts where airtightness is not required.

  As other conductive liquid leakage detection lines, for example, those described in the following Patent Document 4 (Japanese Patent Publication No. 2002-525566) are also known. The conductive liquid leakage detection line is formed by connecting an insulator that is impermeable to the conductive fluid surrounding the conductive line between adjacent winding turns so that there is an insulating gap in which the conductive line is released from the insulator. It is constituted by at least one insulating tape spirally wound on the conductive wire with an axial winding gap. This is the same as described above in that the conductive wire is electrically detected by the conductive fluid leaking in the insulator gap released from the insulator.

  However, in the above-described conventional conductive liquid leak detection line, if moisture enters the conductive line from between the insulators, the insulation resistance between the conductive line and the piping is lowered, and the short-circuit between the conductive line and the conductive line As a result, the detection current flows. As a result, a false alarm may be issued as a result of leakage of conductive liquid such as liquid metal sodium.

JP 2008-26264 A JP 2003-35694 A JP 2002-277341 A JP-T-2002-525566

In the present invention, in view of the problems in such a conventional conductive liquid leakage detection line, water does not penetrate into the insulator, and the conductive line is formed only by contact with liquid metal sodium which is a conductive liquid to be detected. It is designed to be short-circuited and connected to monitoring equipment such as piping and containers. An object is to reliably detect leakage of a conductive liquid while preventing the occurrence of malfunction due to the ingress of moisture.

   In order to achieve the above object, the present invention covers a conductive wire with an insulating material that is not eroded by moisture but is eroded by the conductive liquid to be detected, and this insulating material prevents the penetration of moisture into the conductive wire. While blocking, a weak electric current is passed through the conductive wire to electrically detect a short circuit or conduction between the conductive wire and an object to be inspected such as a container or pipe.

That is, the present invention is a linear conductive liquid leakage detection line for detecting that the conductive liquid to be detected leaks from the inspected object 1 containing the conductive liquid, and the conductive line liquid to be detected. Is a liquid metal sodium, is non-erodible to moisture , and covers the entire conductive wire 4 with an insulating material 3 made of glass that is erodible to the liquid metal sodium to be detected. A portion of the wire 4 covered with the insulating material 3 is attached to the device under test 1, and a short circuit or conduction between the wire 4 and the device under test 1 is detected by energization between the wire 4 and the device under test 1.

More specifically , the conductive wire 4 is covered with an insulating material 3 made of glass that is non-erodible to moisture and erodible to the liquid metal sodium. For example, as the insulating material 3, PbO glass or Bi ₂ O ₃ glass is used. In particular, Bi ₂ O ₃ -based glass is excellent in erosion with respect to liquid metal sodium and has good sensitivity.

In such a conductive liquid leakage detection line according to the present invention, since the entire conductive line 4 is covered with the insulating material 3 made of glass that is non-erodible to moisture, moisture will come into contact with the conductive line 4. However, it is protected by the insulating material 3 and contact is prevented. On the other hand, the insulating material 3 made of glass has a erosive for the liquid metal sodium is a conductive liquid to be detected, when the conductive liquid is brought into contact with the insulating material 3, the insulating material 3 is conductive liquid The insulating material 3 is eroded by contact and reaction. As a result, the conductive liquid penetrates into the insulating material 3, contacts the conductive wire 4, and is electrically connected between the conductive wire 4 and the device under test 1. Accordingly, the portion of the conductive wire 4 covered with the insulating material 3 is attached to the device under test 1 and, at the same time, the current between the conductive wire 4 and the device under test 1 is detected to detect a short circuit or conduction between them. Reliably detect leakage of conductive fluid.

As described above, in the conductive liquid leakage detection line according to the present invention, moisture does not contact the conductive line 4, and only the liquid metal sodium, which is a conductive liquid , penetrates into the insulating material 3 made of glass , and the conductive line 4 in contact. Therefore, the conductive wire 4 and the device under test 1 are short-circuited only by the conductive liquid. For this reason, malfunction due to moisture is eliminated, and leakage of the conductive fluid can be reliably detected. Therefore, a highly reliable conductive liquid leak detection line can be obtained.

It is a whole schematic sectional drawing which shows one Example of the electroconductive liquid leak detection line by this invention. It is a principal part expansion schematic sectional drawing which shows the detection line part of one Example of the electroconductive liquid leak detection line by this invention. It is a principal part expansion schematic sectional drawing which shows the detection line part of the other Example of the electroconductive liquid leak detection line by this invention. It is a graph which shows the change with respect to the temperature of the production free energy of glass material. It is a whole schematic sectional drawing which shows the prior art example of an electroconductive liquid leak detection line.

The present invention uses an insulating material that is not eroded by moisture, but is eroded by the conductive liquid to be detected. A short circuit and conduction with the object to be inspected are caused to achieve the above object.
Hereinafter, embodiments of the present invention will be described specifically and in detail with reference to the drawings.

FIG. 1 is an overall schematic cross-sectional view showing an embodiment of a conductive liquid leakage detection line according to the present invention and an inspection circuit diagram of a detection unit, and FIG. FIG.
The detection wire 2 that forms the main body of the conductive liquid leakage detection wire uses a wire such as nickel or copper having a diameter of about φ1.2 as the conductive wire 4, and passes the conductive wire 4 through the insulating material 3 formed in a tube shape. The conductive wire 4 is drawn out to both ends of the insulating material 3 through end plugs 5 and 5 which close both ends of the tubular insulating material 3. PbO glass or Bi ₂ O ₃ glass is used as the end plug 5. Such a detection line 2 is attached to an object to be inspected 1 containing a conductive line liquid such as a pipe or a container.

  The detection unit 6 for electrically detecting the leakage of the conductive fluid from the test body 1 by the detection line 2 is conducted through a power source 8 that supplies a weak current to the conductive line 4 and a test switch 7. An ammeter 9 connected to the wire 4 and electrically detecting that a weak current flows through the conductive wire 2 due to conduction and short circuit between the conductive wire 4 and the pipe 1 is included. When monitoring the leakage of the conductive fluid from the test body 1, the switch 7 is opened. On the other hand, when the switch 7 is closed, a weak current energized from the power source 8 through the conductive wire 4 is detected by the ammeter 9, so that a continuity test of the conductive wire 4 can be performed.

Even when moisture contacts the detection line 2 with the test switch 7 open, the conductive wire 4 is protected by the insulating material 3 and the moisture does not contact the conductive wire 4. In contrast, when the insulating material 3 is erodible to the conductive liquid to be detected, when the conductive liquid contacts the insulating material 3, the conductive liquid contacts and reacts with the insulating material 3, The insulating material 3 is eroded. As a result, the conductive liquid penetrates into the insulating material 3 and comes into contact with the conductive wire 4, and an electrical short circuit or conduction between the conductive wire 4 and the device under test 1 occurs. At this time, the leakage of the conductive fluid from the test body 1 can be detected by detecting the application of a weak current with the ammeter 9.

For this reason, the insulating material 3 needs to be a material that is non-erodible to moisture and erodible to a conductive liquid to be detected for leakage. Specifically, glass, in particular, PbO-based glass or Bi ₂ O _3- based glass is used as the insulating material 3 in which the conductive liquid to be detected for leakage is erodible to liquid metal sodium . In particular, Bi ₂ O ₃ -based glass is excellent in erosion with respect to liquid metal sodium and has good sensitivity.

FIG. 3 is an enlarged schematic cross-sectional view of a main part showing a part of the detection line 2 of another embodiment of the conductive liquid leakage detection line according to the present invention. In this embodiment, the insulating material 3 ′ is not formed in a tube shape, but is formed in close contact so as to cover the entire conductive wire 4. As the insulating material 3 ′ to be used, the same insulating material 3 as in the above-described embodiment is used. When the insulating material 3 ′ is brought into close contact with the conductive wire 4 as shown in FIG. 3, the thermal expansion coefficient must be the same. Therefore, PbO-based glass or Bi ₂ O _3- based glass is used as the insulating material 3 ′. For the wire 4, it is preferable to use a sealing metal Kovar or nickel iron alloy having a small thermal expansion coefficient close to that of the insulating material 3 ′.

FIG. 4 is a graph comparing the temperature change of the free energy of formation of PbO glass or Bi ₂ O ₃ glass used as the insulating material 3 with normal lime soda glass (Na ₂ O glass). (So-Soshinsha 1987 "Thermochemistry of Oxides" and Japan Institute of Metals 1964 "Metallurgy Physical Chemistry"). As is apparent from this graph, the PbO-based glass and Bi ₂ O ₃ -based glass used as the insulating material 3 are in the operating temperature range of 300 ° C. to 500 ° C. compared to normal lime soda glass (Na ₂ O-based glass). The free energy of formation at ℃ is large, and it is easy to react with liquid metal sodium. However, glass does not react with moisture, and there is no problem in protecting the conductive wire 4 against moisture.

  The conductive liquid leakage detection line according to the present invention can detect that the liquid metal sodium has leaked from the pipe for storing the liquid metal sodium or the container for storing the liquid metal sodium without being disturbed by moisture. It can be applied to monitoring sodium leakage.

DESCRIPTION OF SYMBOLS 1 Inspection body 2 Detection line 3 Insulating material 4 Conductive line 6 Detection part 8 Power supply 9 Ammeter

Claims (4)

A linear conductive liquid leakage detection line for detecting that the conductive liquid to be detected has leaked or entered from the inspection object (1) containing the conductive liquid, and the conductive line liquid to be detected Is the liquid metal sodium, is non-erodible to moisture , and is the entire conductive wire (4) with an insulating material (3) made of glass that is erodible to the liquid metal sodium to be detected. The portion covered with the insulating material (3) of the conductive wire (4) is attached to the object to be inspected (1), and energization between the conductive wire (4) and the object to be inspected (1) is performed. A conductive liquid leak detection line characterized by detecting a short circuit and conduction between them. The conductive liquid leakage detection line according to claim 1, wherein the insulating material (3) has a tube shape, and the conductive line (4) is passed through the insulating material (3). The conductive liquid leakage detection line according to claim 1, wherein the insulating material (3) covers the entire conductive line (4) in close contact. The insulating material (3) made of glass is PbO-based glass or Bi ₂ O ₃ -based glass having erodibility to the liquid metal sodium to be detected. The conductive liquid leakage detection wire described.

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