JPS59109823A - Liquid level gauge for liquid metal - Google Patents

Abstract

PURPOSE:To make a plant compact, by forming a protection tube with a shape memory alloy in the liquid level gauge for liquid metal where plural detectors where exciting coils and detecting coils are combined are arranged at intervals of a prescribed length in the protection tube. CONSTITUTION:Detectors 4 each of which consists of fixed point-type detecting coils and a fixed point-type exciting coil 3 are arranged at intervals of a prescribed length in a protection tube 1. In this case, the protection tube 1 is formed with a shape memory alloy; and as the result, when the protection tube 1 is inserted to a liquid level gauge well 10, it is returned to the shape before deformation because of a high temperature in a tank or the like even if it has a free shape on the outside. Consequently, it is possible to reduce considerably the space for pulling out the liquid level gauge in the upper part of an apparatus or the like, and the plant is made compact.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a liquid metal level gauge suitable for measuring the liquid level of liquid metal helium of a cold comb 11 material used in a fast breeder reactor, for example. .

[Technical background of the invention and its problems] In order to put fast breeder reactors into practical use and commercialize them, cost reduction, such as making the plant more compact, is an important issue. However, this problem has become more difficult due to the increase in the size of equipment accompanying the increase in human output. Particularly, liquid level gauges used in sodium tanks, etc., have to measure as much as the height of the tank due to their functionality, and the liquid level side must be pulled out during maintenance, etc. etc., (11 spaces as large as firearms)
c must be maintained. This space becomes extremely large considering the increase in sodium inventory due to the increase in the size of the equipment, and keeping this space small is extremely effective in making the plant more compact.

In order to avoid reducing the space required to pull out the level gauge, the structure of the level gauge is made flexible and the bottom of the tank is
One idea is to make it so that they do not have to be handled separately. For this purpose, it is possible to form several parts of the protection tube with bellows, but this has the drawback that the measurement accuracy decreases due to the drawing of the bellows, and the original function of the liquid level gauge is reduced to 1. .

[Object of the Invention] The present invention has been made to solve the above-mentioned drawbacks, and provides a level gauge for liquid metal that can reduce the space for pulling out the level gauge without sacrificing measurement accuracy. It's about doing.

[Invention 11] In order to achieve the above object, the present invention provides a level gauge for liquid metal in which a plurality of detection elements each including an excitation coil and a detection coil are arranged at predetermined intervals in a protection tube. It is characterized by being made of a shape memory alloy, which reduces the space required to pull out the level gauge, thereby effectively making the fast breeder reactor plant more compact.

[Embodiment of the Invention] An embodiment of the liquid surface side according to the present invention will be described in detail below with reference to the drawings.

In FIG. 1, reference numeral 1 denotes a bottomed protection tube made of a shape memory alloy, and a fixed point detection coil 2 d3 J: and a fixed point excitation coil 3 are connected at a predetermined interval within this protection tube 1. Detecting elements 4 are arranged. In addition, as shown in FIG. 2, which shows an enlarged view of the surroundings of the sensing element 4, the coil 2.3 is placed in contact with the sensing cord 4 so as not to cause deformation of the coil 2.3 due to plastic deformation of the storage tube 1 made of a shape memory alloy. A protection ring 5 is provided on the inner surface of the protection tube 1. The protective ring 5 is a reinforcing body and is fitted into a groove 6 formed on the inner surface of the protective tube 1.

A flange 7 is connected to the upper end of the storage tube 1, and the flange 7 is fixedly connected to the cable attachment cylinder 8 via the other flange 7a. The cable attachment cylinder 8 is provided with a shielded cable attachment portion 8a, and an upper 9
C) is hermetically sealed with a lid 9. FIG. 3 shows the liquid level gauge having the above structure inserted into the level gauge well 10. That is, the well 10 is inserted into the level gauge nozzle 11, and a cooler 12 is installed at the upper end of the level gauge nozzle 11.
A cylindrical body 13 for fixing is connected. A protective tube 1 to which the flange 7 is connected is inserted into the well 10 from an upward angle of the cylindrical body 13.

The liquid level gauge according to the present invention is a fixed point type induction type liquid level gauge. The operating principle of this liquid level gauge is the excitation coil (primary coil) 3
It utilizes the fact that when excited with alternating current, the voltage induced in the detection coil (secondary coil) 2 changes with the liquid level of the liquid metal sodium.

In other words, in Fig. 1, an alternating current is passed through the fixed point excitation coil (primary coil) 3, and the voltage induced in the fixed point detection coil (secondary coil) 24 changes depending on the presence of liquid metal sodium in the surrounding area. take advantage of things.

In addition, the fixed point type liquid surface side is used to detect large changes in the liquid total sodium liquid level, and is several hundred m+
The detection elements 4 are arranged at a certain pitch. Symptom ■
A change in liquid level is detected by another liquid level gauge that detects only a certain height.

Next, the shape memory alloy used for the protective tube of the liquid level gauge according to the present invention will be explained.

Shape memory alloys are alloys that have the property of returning to the shape before deformation when the alloy is plastically deformed and heated above the temperature specific to the alloy.Ti-Nt
, Au Cd, Cu-14AI-1゜6Ni, C
There are u3Al, CLI-'I1Zn, etc.

This effect is due to thermoelastic martensitic transformation. Typical of these alloys are Ni and Ti.
It is a Ni-Ti alloy containing almost the same amount of , and has good corrosion resistance, wear resistance, and heat resistance. The shape memory alloy used in the present invention is not limited to Ni-Ti alloys, but since it is used in fast breeder reactors, high-temperature strength is required, and the following is limited to Ni-Ti alloys that can ensure sufficient high-temperature strength. Continue to explain.

In addition to the above-mentioned advantages, the N1/T1 alloy has the following advantages:
Although it is an intermetallic alloy, it has good workability. However, cold working is almost impossible, and welding is limited to the same area. Regarding high temperature strength, within the temperature range used in fast reactors,
A-Higher than stenite stainless steel and sufficient.

The problem is the compatibility with liquid sodium used as a coolant in fast breeder reactors, and the compatibility of Ni with liquid sodium is fully recognized as J3. Since it is an element with a strong tendency to ionize, it is thought that there will be no major problems, and compatibility with liquid sodium can be expected.

Therefore, when inserted into the liquid level well 10 according to the present invention, even if it is shaped freely on the outside, it returns to the shape before deformation because of the high temperature inside the tank or the like. However, when pulling out, the temperature of the liquid level gauge must be kept below the transformation point of the shape memory alloy. Therefore, the cooling device 12
This makes it possible to extract the cold ram (IL tank, etc.) even if the outside exhaustion reaches the transformation point or higher.

Moreover, the protective ring 5 does not have a negative effect on the detection element 4 even if the protective tube 1 is deformed! Kome no Chino.

``Effects of the invention'' As described above, according to the present invention, it is possible to bend the liquid level in any direction and pull it out. This makes it possible to significantly reduce the space required, which has a great effect on converting the plant to a single unit.

Note that since the Ni--Ti alloy is a paramagnetic material, it does not form a magnetic loop with the excitation coil, etc., and therefore does not interfere with the ability to detect the liquid level G1.

[Brief explanation of the drawing]

FIG. 1 is a vertical cross-sectional view partially showing a side view of an embodiment of the liquid level tear according to the present invention, FIG. 2 is a vertical cross-sectional view showing an enlarged portion A of FIG. FIG. 2 is a longitudinal cross-sectional view partially showing a state in which the level gauge shown in the figure is installed in a level gauge well. 1......Protective tube 2...Detection coil 3...
......Exciting coil 4......Detection element 5...Protection ring 6...
・・・・・・Sub7・・・・・・・・・Flange 10・・・・・・・・・・・・1 liquid level G]-ru 11・
......Liquid level gauge nozzle 12...
・・・・・・Cooling device Fig. 1 121 Fig. 3

Claims (1)

[Scope of Claims] (1) A level gauge for liquid metal in which a plurality of sensing elements each including a combination of an excitation coil and a detection coil are arranged at predetermined intervals in a protection tube, wherein the protection tube is made of a shape memory alloy. A liquid level gauge for liquid metals. (2) A level gauge for liquid metal according to claim 1, characterized in that a cooling device is attached to the upper side of the protection tube. (3) A reinforcing member is provided on the inner surface of the protection tube where the detection element is located. A liquid level gauge for liquid metal according to claim 1, characterized in that the liquid metal level gauge is provided with: