JP5922413B2 - Liquid metal leak detector - Google Patents

Description

  The present invention relates to a liquid metal leak detector, and is devised so that liquid metal leak can be detected early and reliably even if the detection target region is wide.

In the next generation energy system, the fast breeder reactor (FRB), liquid metal sodium will be adopted as a coolant.
By the way, when liquid metallic sodium reacts with the atmosphere, there is a risk of a serious accident such as a metal fire due to the chemical activity of sodium itself. In addition, alkaline corrosion products resulting from the reaction of liquid metal sodium with the atmosphere, etc. may cause corrosion of piping, components, machinery, etc., leading to large leaks and loss of coolant due to this corrosion. There is sex.

  Therefore, in the unlikely event that the liquid metal sodium leaks, it is necessary to first take early detection of the leak and secondly take measures.

  There are various methods such as contact type, ionization type, differential pressure type, and radiation ionization type as the current leakage detection method for liquid metal sodium, and the method used depends on the installation environment, but the simple and reliable method is It is a contact type.

  Here, various conventional examples of contact-type sodium leakage detectors that detect leakage of liquid metal sodium will be described.

In the sodium leak detector 10 shown in FIG. 16, a pair of rod-shaped electrodes 12 a and 12 b protrude from the end surface of the cylindrical insulating support portion 11. The electrodes 12a and 12b have their base portions (portions excluding protruding portions) embedded in the insulating support portion 11, and a positive voltage is applied to the electrode 12a and a negative voltage is applied to the electrode 12b.
When the leaked liquid metal sodium adheres to the electrodes 12a and 12b in a state of connecting the electrodes 12a and 12b, an electrical short circuit occurs. When this electrical short circuit occurs, the sodium detector 10 reacts and detects that the liquid metal sodium has leaked, so the user can primarily determine that "sodium has leaked".

In the sodium leak detector 20 shown in FIG. 17, a curved electrode 22 protrudes from the end surface of the cylindrical insulating support portion 21. The electrode 22 has a base portion (a portion excluding the protruding portion) embedded in the insulating support portion 21, and a voltage is applied to the electrode 22. A cylindrical earth electrode 23 is disposed on the peripheral surface of the insulating support portion 21.
If the leaked liquid metal sodium adheres to the electrodes 22 and 23 in a state where the electrode 22 and the ground electrode 23 are connected, an electrical short circuit occurs. When this electrical short circuit occurs, the sodium leak detector 20 reacts and detects that the liquid metal sodium has leaked, so the user can primarily determine that “sodium has leaked”.

In the sodium leak detector 30 shown in FIG. 18, the linear electrode 31 is drawn out from the connector portion 32, and the linear electrode 31 is provided with a plurality of insulating tubes 33. For this reason, the electrode 31 is exposed at a portion where the insulating tube 33 is not mounted. A voltage is applied to the electrode 31.
A plate-like ground electrode 34 is disposed along the electrode 31.
If the leaked liquid metal sodium adheres to the electrodes 31 and 34 in a state where the exposed portion of the electrode 31 and the ground electrode 34 are connected, an electrical short circuit occurs. When this electrical short circuit occurs, the sodium leak detector 30 reacts and detects that the liquid metal sodium has leaked, so the user can primarily determine that “sodium has leaked”.

JP-A-4-34394

The contact-type sodium leak detector described above is disposed, for example, on the surface (upper surface) of a tray (liner) disposed below (directly below) an apparatus using liquid metal sodium.
The “apparatus using liquid metal sodium” is used in the present specification as including various apparatuses (for example, sodium heater), containers, and pipes using liquid metal sodium.

As shown in FIG. 19, in the sodium heater 50, a heating burner 52 and a heat transfer tube 53 are disposed in a casing 51, and pipes 54 a and 54 b are disposed in a state of penetrating the casing 51. A pipe 54 a is connected to the inlet end of the heat transfer pipe 53, and a pipe 54 b is connected to the outlet end of the heat transfer pipe 53.
The liquid metal sodium is sent through the pipe 54a, flows through the heat transfer pipe 53, and is sent out through the pipe 54b. The liquid metallic sodium is heated by the heating burner 52 while flowing through the heat transfer tube 53.
A saucer 55 is installed immediately below the sodium heater 50. The contact-type sodium leak detector described above is disposed on the surface (upper surface) of the tray 55.

Both contact-type sodium leak detectors detect leaks by utilizing the fact that an electrical short circuit occurs when conductive liquid metal sodium adheres to the electrodes of a sodium leak detector. The more facilities you have, the more you have to install.
Moreover, since the leaked liquid metal sodium finally reaches the tip of the electrode through the tray (liner), there is a problem that it takes time to detect.
On the other hand, the number of installations must be increased in order to identify the leaked part and shorten the detection time. When the number of installations is increased, the required electric circuit of the detector becomes large, and there is a problem that the system becomes complicated.

  The present invention provides a liquid metal leakage detector that can detect liquid metal leakage in a wide detection target area early and reliably even if the number of detectors is reduced in view of the above-described conventional technology. For the purpose.

The configuration of the present invention for solving the above problems is as follows.
An insulative base disposed at an angle with respect to a horizontal plane, which constitutes a saucer disposed below a device using liquid metal;
A first electrode surface formed on the surface of the substrate to which a positive voltage is applied;
A second electrode surface formed on the surface of the substrate, adjacent to the first electrode surface and to which a negative voltage is applied;
A line meanderingly formed on the surface of the base, separating the first electrode surface and the second electrode surface to electrically insulate and mechanically separate them, and the longitudinal An insulating line groove having a direction perpendicular to the inclination direction of the substrate;
It is characterized by having .

The configuration of the present invention is as follows.
The insulating line grooves are formed so that the arrangement interval is widened toward the upper side of the base plate arranged at an inclination, and the arrangement interval is narrowed toward the lower side of the base board arranged at an inclination. It is characterized by.

  According to the present invention, it is possible to detect liquid metal leakage early and reliably even if the detection target region is wide.

The top view which shows the sodium leak detector which concerns on Example 1 of this invention. II-II sectional drawing of FIG. The top view which shows the sodium leak detector which concerns on Example 2 of this invention. The block diagram which shows the sodium leak detector which concerns on Example 3 of this invention. The block diagram which shows the sodium leak detector which concerns on Example 4 of this invention. The top view which shows the sodium leak detector which concerns on Example 6 of this invention. The perspective view which shows the sodium leak detector which concerns on Example 7 of this invention. Sectional drawing which shows the sodium leak detector which concerns on Example 7 of this invention. Sectional drawing which shows the sodium leak detector which concerns on Example 7 of this invention. The characteristic view which shows the surface tension of liquid metallic sodium and water. The perspective view which shows the sodium leak detector which concerns on Example 9 of this invention. Sectional drawing which shows the sodium leak detector which concerns on Example 9 of this invention. Sectional drawing which shows the sodium leak detector which concerns on Example 9 of this invention. The perspective view which shows the sodium leak detector which concerns on Example 10 of this invention. The block diagram which shows the sodium leak detector which concerns on Example 11 of this invention. The block diagram which shows the conventional sodium leak detector. The block diagram which shows the conventional sodium leak detector. The block diagram which shows the conventional sodium leak detector. Sectional drawing which shows a sodium heater.

  Hereinafter, embodiments of the present invention will be described in detail based on examples. In addition, the part which fulfill | performs the same function in each Example is attached | subjected the same code | symbol, and the overlapping description is abbreviate | omitted.

  1 is a plan view showing a sodium leakage detector 110 according to Embodiment 1 of the present invention, and FIG. 2 is a sectional view taken along the line II-II in FIG. In addition, although the electrode surface formed by metal vapor deposition is actually a thin thin film layer, it is drawn thick in FIG. 2 for easy understanding.

  As shown in both figures, the sodium leak detector 110 is electrically insulated from the surface of the base 111 made of an insulator by an insulating line groove 112 and mechanically (spatially) separated from two electrode surfaces. 113a and 113b are formed.

In the sodium leak detector 110 of this example, the base 111 made of an insulator uses the base of the insulator constituting the tray (liner) as it is. A saucer is arrange | positioned under the apparatus (for example, sodium heater) which uses liquid metal sodium (position immediately under).
The substrate 111 is formed of an insulator, but a ceramic material (such as alumina) or a glass material that does not react with liquid metal sodium is used as the insulator.

  The manufacturing procedure of the sodium leak detector 110 will be described. First, a metal that conducts electricity is deposited on the surface (upper surface) of the substrate 111. Next, the insulating line groove 112, which is one line that is bent and meandered, is formed by cutting out the deposited metal along one line that meanders while being bent. Thus, by forming the insulating line groove 112 by the notch, the metal surface deposited on the surface of the base 111 is partitioned into the electrode surface 113a and the electrode surface 113B.

The power source 200 has a positive electrode connected to the electrode surface 113a and a negative electrode connected to the electrode surface 113b via the electric wire 201. Further, a short circuit detector 202 is connected to the electric wire 201. The short-circuit detector 202 is a device that can detect that a short-circuit has occurred when a short-circuit current flows even instantaneously.
A voltage is applied to the electrode surfaces 113a and 113b by the power source 200.

  In a healthy state in which there is no leakage of liquid metal sodium, the electrode surfaces 113a and 113b to which a voltage is applied are electrically insulated and mechanical (spatial) by the base 111 and the insulating line groove 112 which are insulating parts. And no current flows through the electric wire 201.

When liquid metal sodium leaks from a device using liquid metal sodium, the leaked liquid metal sodium flows onto the sodium leak detector 110 and flows into the insulating line groove 112 in a state of connecting the electrode surfaces 113a and 113b. An electrical short circuit occurs.
When an electrical short circuit occurs and a short circuit current flows through the electric wire 201 and this is detected by the short circuit detector 202, it can be determined that the liquid metal sodium has leaked.

  In this embodiment, since the base 111 of the sodium leak detector 110 is configured by the base of the saucer itself, even if the number of detectors is reduced, liquid metal sodium leak in a wide detection target area can be detected early and reliably. can do

In the second embodiment, the leakage detection sensitivity is adjusted by adjusting the interval between the insulating line grooves 112 in consideration of the assumed leakage amount of liquid metal sodium.
That is, when the amount of liquid metal sodium leaked is large, the interval between the insulating line grooves 112 is increased as shown in FIG.
When the amount of liquid metal sodium leakage is assumed to be medium, the interval between the insulating line grooves 112 is set to a medium as shown in FIG.
When the amount of liquid metal sodium leakage is small, the interval between the insulating line grooves 112 is narrowed as shown in FIG.

  In the second embodiment, the leakage detection sensitivity can be adjusted by adjusting the interval between the insulating line grooves 112 in consideration of the assumed leakage amount of liquid metal sodium.

In Example 3, as shown in FIGS. 4A and 4B, the base 111 of the sodium leakage detector 110 is disposed obliquely with respect to the horizontal plane.
In this case, the longitudinal direction of the insulating line groove 112 meandering while being bent is perpendicular to the flow direction f of the liquid metal sodium α that falls in the d direction and flows on the surface of the sodium leakage detector 110 in the f direction. Thus, the arrangement direction of the sodium leakage detector 110 is set.

  In the sodium leak detector 110 according to the third embodiment, the sodium leak detector 110 itself is inclined to allow the liquid metal sodium α that has leaked and dropped to flow out by its own weight. It becomes easy to enter the part, and it becomes possible to detect the leakage early.

  In the fourth embodiment, as shown in FIGS. 5A and 5B, the base 111 of the sodium leakage detector 110 is disposed obliquely with respect to the horizontal plane. Moreover, the density (interval) of the insulating line grooves 112 decreases toward the upper side (left side in FIG. 5) of the sodium leak detector 110, and the density decreases (increases the interval). In FIG. 5, the density is increased (the interval is narrowed) toward the right side.

Since the upper side of the sodium leak detector 110 is close to the device using liquid metal sodium, the temperature is high, and the lower side of the sodium leak detector 110 is away from the device using liquid metal sodium, so it is higher than the upper side. It is cold.
Since the liquid metal sodium has a lower viscosity at a high temperature, the liquid metal sodium dropped on the surface of the sodium leakage detector 110 is likely to flow at a high temperature. It is wide and narrow on the low temperature side (lower side). This eliminates the need for extra insulating line grooves 112 on the high temperature side (upper side).

  In Example 5, electrode surfaces 113a and 113b are formed by vapor-depositing nickel (Ni) or aluminum (Al) on the surface of the base 111 made of an insulator.

Depending on the usage environment, conductive dust such as metal powder and carbon may fly and adhere to the insulating line groove 112, which may result in false alarms, and non-conductive dust may fly and adhere to the insulating line groove 112. Then, there is a possibility that leakage detection sensitivity may be lowered (if the non-conductive dust contains water, it may become a false alarm).
In view of such a use environment, in Example 6, according to the size of the flying material, the cutout width of the insulating line groove 112 (50 μm to 50 μm˜) which is sufficiently larger than the flying material so that the flying material does not fill the insulating line groove 112. About 500 μm).

In a general sodium heater, since the size of the dust is 0.5 μm to several tens of μm, the notch width of the insulating line groove 112 may be about 50 μm as shown in FIG.
On the other hand, when the filter for removing dust is not attached to the sodium heater or when the performance of the filter is low, the notch width of the insulating line groove 112 is set to 100 μm to 500 μm as shown in FIG. It needs to be about.

  In the sixth embodiment, by adjusting the notch width of the insulating line groove 112 according to the size of the flying material, it is possible to prevent the insulation resistance from being lowered, that is, to prevent the false alarm.

In each of the above Examples 1 to 6, the insulating line groove is meandering while being bent, but may be meandering while being curved, and in any case, it becomes a single line on the surface of the base 111. What is necessary is just to arrange | position so that the wide range may be covered as much as possible.
In each of the above Examples 1 to 6, the base of the sodium leak detector uses the insulating base constituting the tray (liner) as it is, but an insulating base different from the base is adopted. It may be. In this case, by adopting a wide base, even if the number of detectors is reduced, leakage of liquid metal sodium in a wide detection target region can be detected early and reliably.
Furthermore, the two electrode surfaces are not limited to vapor deposition, and can be formed by various methods such as etching, patterning, and printing.

  FIG. 7 is a perspective view showing a sodium leakage detector 310 according to Embodiment 7 of the present invention, and FIG. 8 is a sectional view thereof. The conductive film is actually a thin thin layer, but is drawn thick in FIGS. 7 and 8 for easy understanding.

The sodium leakage detector 310 according to the seventh embodiment has a three-layer structure including a conductive substrate 311, an insulating material 312 disposed on the upper surface of the substrate 311, and a conductive film 313 disposed on the upper surface of the insulating material 312. ing.
Further, a plurality of holes 314 are formed in the conductive film 313 and the insulating material 312 so as to reach from the upper surface of the conductive film 313 to the upper surface of the base 311.

  In the sodium leak detector 310 of this example, the base 311 made of a conductor uses the base of the conductor constituting the tray (liner) as it is. A saucer is arrange | positioned under the apparatus (for example, sodium heater) which uses liquid metal sodium (position immediately under).

The power source 200 has a positive electrode connected to the conductive film 313 and a negative electrode connected to the conductive substrate 311 via the electric wire 201. Further, a short circuit detector 202 is connected to the electric wire 201. The short-circuit detector 202 is a device that can detect that a short-circuit has occurred when a short-circuit current flows even instantaneously.
A voltage is applied to the conductive film 313 and the conductive substrate 311 by the power source 200.

  In a healthy state where there is no leakage of liquid metal sodium, the conductive film 313 and the conductive substrate 311 to which a voltage is applied are electrically insulated and mechanically (by an insulating material 312 and a hole 314 which are insulating parts). It is separated spatially, and no current flows through the electric wire 201.

The liquid metal sodium leaks from the device using the liquid metal sodium, and the leaked liquid metal sodium flows onto the sodium leak detector 310, so that the liquid metal sodium α is put in the hole 314 as shown in FIG. When entering and connecting the conductive film 313 and the conductive substrate 311, an electrical short circuit occurs.
When an electrical short circuit occurs and a short circuit current flows through the electric wire 201 and this is detected by the short circuit detector 202, it can be determined that the liquid metal sodium has leaked.

  In this embodiment, since the base 311 of the sodium leak detector 310 is configured by the base of the saucer itself, even if the number of detectors is reduced, liquid metal sodium leak in a wide detection target area can be detected early and reliably. can do

In Example 8, the diameter of the hole 314 of the sodium leak detector 310 is 3 mm or more.
As shown in FIG. 10, the surface tension of liquid metal sodium is about three times the surface tension of water. Even if the liquid metal sodium has a large surface tension, the leaked liquid metal sodium enters the hole 314 without staying only at the upper part of the hole 314 by setting the diameter of the hole 314 to 3 mm or more. Leakage can be detected.

  In Example 9, as shown in FIGS. 11 and 12, a plurality of holes 314 are formed in a three-layer structure including a conductive substrate 311, an insulating material 312, and a conductive film 313, and the conductive film 313 An insulating sheet 315 is disposed on the upper surface. Thereby, the upper surface of the conductive film 313 and the upper surface of the hole 314 are covered.

As the insulating sheet 315, a material that melts when high-temperature liquid metallic sodium leaking adheres is used.
For example, when the temperature of the leaked liquid metal sodium is 390 ° C. or higher, the insulating sheet 315 is made of polytetrafluoroethylene (Teflon (registered trademark)) having a decomposition start temperature of about 390 ° C. (melting point: 327 ° C.). ) Can be used.
When the leaked liquid metal sodium has a slightly lower temperature, the insulating sheet 315 can be made of, for example, rubber. For example, in the case of silicone rubber, the heat resistant limit temperature is 230 ° C.

In this embodiment, even if there are many impurities such as particles in the atmosphere and the holes 314 may be blocked by the impurities, the holes 314 are blocked by the impurities because the holes 314 are covered with the insulating sheet 315. This can be prevented.
As a result, it is possible to prevent false alarms even when the conductive material is blown off, and even when the non-conductive material is blown off, it is possible to prevent the detection from being blocked due to the blockage of the hole 314.

When high-temperature liquid metal sodium leaks from a device that uses liquid metal sodium, and the leaked liquid metal sodium flows onto the sodium leak detector 310, the liquid metal sodium α is insulated as shown in FIG. When the sheet 315 is melted and enters the hole 314 to connect the conductive film 313 and the conductive substrate 311, an electrical short circuit occurs.
When an electrical short circuit occurs and a short circuit current flows through the electric wire 201 and this is detected by the short circuit detector 202, it can be determined that the liquid metal sodium has leaked.

In Example 10, as shown in FIG. 14, the base 311 of the sodium leak detector 310 is disposed obliquely with respect to the horizontal plane.
In the sodium leak detector 310 of the tenth embodiment, the sodium leak detector 310 itself is inclined, so that the liquid metal sodium α that has leaked and dropped in the d direction flows out in the f direction by its own weight, and the hole 314 It becomes easy to enter any part of the above, and it becomes possible to detect leakage early.

  In Example 11, as shown in FIGS. 15A and 15B, the base 311 of the sodium leakage detector 310 is disposed obliquely with respect to the horizontal plane.

Further, a large number of holes 314 are formed on the surface of the base 311, but the holes 314 are alternately formed.
In other words, a plurality of hole columns in which a plurality of holes 314 are formed while being spaced apart in parallel in the row direction L are arranged apart in the column direction R orthogonal to the row direction L. Moreover, the arrangement position in the row direction L of the hole 314 in the hole row adjacent to the arbitrary one hole row is only a half pitch with respect to the arrangement position in the row direction L of the hole 314 in any one hole row. It's off.

  In the sodium leakage detector 310 of the eleventh embodiment, the sodium leakage detector 310 itself is inclined so that the liquid metal sodium α that has leaked and dropped flows under its own weight, and the holes 314 are staggered at that time. Since it is arranged, the liquid metal sodium α easily enters any part of the hole 314, and leakage can be detected at an early stage.

In each of the above Examples 7 to 11, the base of the sodium leak detector uses the conductive base constituting the tray (liner) as it is, but a conductive base different from the base is adopted. It may be. In this case, by adopting a wide base, even if the number of detectors is reduced, leakage of liquid metal sodium in a wide detection target region can be detected early and reliably.
Further, the conductive film 313 may be formed so as to enter the inner peripheral surface of the hole 314 as long as the conductive film 313 does not reach the conductive substrate 311.

  In the present invention, it is possible to detect leakage of not only liquid metal sodium but also other kinds of liquid metal having conductivity.

50 Sodium heater 51 Casing 52 Heating burner 53 Heat transfer tube 54a, 54b Pipe 55 Receptacle (liner)
DESCRIPTION OF SYMBOLS 110 Sodium leak detector 111 Base 112 Insulation line groove 113a, 113b Electrode surface 200 Power supply 201 Electric wire 202 Short circuit detector 310 Sodium leak detector 311 Base 312 Insulation material 313 Conductive film 314 Hole 315 Insulation sheet

Claims (2)

An insulative base disposed at an angle with respect to a horizontal plane, which constitutes a saucer disposed below a device using liquid metal;
A first electrode surface formed on the surface of the substrate to which a positive voltage is applied;
A second electrode surface formed on the surface of the substrate, adjacent to the first electrode surface and to which a negative voltage is applied;
A line meanderingly formed on the surface of the base, separating the first electrode surface and the second electrode surface to electrically insulate and mechanically separate them, and the longitudinal An insulating line groove having a direction perpendicular to the inclination direction of the substrate;
Leak detector of the liquid metal, characterized in that it comprises a. In claim 1,
The insulating line grooves are formed so that the arrangement interval is widened toward the upper side of the base plate arranged at an inclination, and the arrangement interval is narrowed toward the lower side of the base board arranged at an inclination. A liquid metal leak detector.

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