JPH0351708A - Assembly of ultrasonic transducer - Google Patents

Abstract

PURPOSE:To keep excellent adhesion by cooling a case in a metal-film forming step, thereafter immersing the metal case into liquid having excellent leaking property within an inactive atmosphere and attaching a liquid film. CONSTITUTION:In a surface treating step 23, a metal case 1 is heated in inactive gas. In a next metal-film forming step 24, the case 1 is immersed into high temperature pure liquid metal and solidified. Thus, a metal film 28 is formed. Then, the metal film 28 is immersed into liquid having excellent leaking property with the case 1 in a liquid-film forming step 25, and a thin film 29 is formed. Then, the case 1 which is treated in a normal-temperature solidified-film forming step 26 is immersed into liquid which is liquified into liquid by heating. The liquid is in the solid state at the normal temperature. A film 30 which is solidified at normal temperature is formed on the liquid film 29. An ultrasonic vibrator assembling step 27 is performed in the case 1 wherein the solidified film 30 is formed. Thus, the assembling is finished. The liquid film 29 having the excellent leaking property is formed in the step 25, and the excellent adhesion can be kept.

Description

Detailed Description of the Invention [Objective of the Invention] (Industrial Application Field) The present invention relates to recognition of the position and shape of structures in a nuclear reactor vessel filled with liquid metal, such as liquid sodium, and various equipment in the reactor. The present invention relates to a method of assembling an ultrasonic transducer used in an ultrasonic fluoroscope.

(Prior Art) A conventional high temperature ultrasonic transducer will be described with reference to FIG. That is, in FIG. 3, the opening 1 of the cylindrical stainless steel metal case 1! cover 2
The container is sealed and assembled by welding to form a sealed container. A disk-shaped high-temperature ultrasonic transducer 3 made of lithium niobate is disposed on the bottom inner surface of the metal case 1 . This ultrasonic transducer 3 has a Curie point of 1200°C, an electromechanical coupling coefficient Kl (Kl =, /- mechanical output energy/electrical input energy) of 0.17, and a frequency of 2.5 MH!
, with a pulse width of approximately 50 μHe. Code 5 is 800
The high-temperature ultrasonic transducer 3 is bonded to the bottom inner surface of the metal case 1 using silver paste, which is a bonding member fired at .degree. Reference numeral 6 denotes a hermetic type seal connector that is attached through the cover 2, and 7 is an electric wire covered with a silicone rubber tube, which connects the seal connector 6 and the electrode 4 of the high-temperature ultrasonic transducer 3. 8 is an M1 cable (Minerxl In
5ulated Cxble).

A conventional high-temperature ultrasonic transducer has a sealed container containing a high-temperature ultrasonic vibrator 3 made of lithium niobate whose Curie point is 1200°C, and has a metal case 1 and a cover 2.
Therefore, the usage conditions are temperature 200℃~250℃,
Radiation 1. Oxlo Rad has corrosion resistance even inside the reactor vessel and can be used for a long period of time. Furthermore, when a predetermined voltage is applied to the high-temperature ultrasonic transducer 3 sealed by the metal case 1 and cover 2, the frequency is 2.5MH! An ultrasonic wave with a pulse width of 50 μsec is oscillated, and when the ultrasonic wave passes through the bottom of the metal case 1, it is attenuated or reflected and sent out of the metal case 1.

An ultrasonic transducer having such a configuration is used, for example, in a sodium fluoroscope in a fast breeder reactor shown in FIG. That is, in FIG. 4, the upper end opening 10 of the reactor vessel 9 is closed with a fixed plug 11 and a rotating plug 12, and a reactor core 13 consisting of a large number of fuel assemblies and control rods is inside the reactor vessel 9. It is located. Liquid sodium coolant 15 flows through this reactor core 13 from an inlet pipe 14, removes heat, and flows out from an outlet pipe 16. A core upper mechanism 17 is placed directly above the reactor core 13 on the rotary plug 12 and whose terminal extends above the reactor core 13.
is provided. Further, an ultrasonic fluoroscope 18 is provided passing through the fixed plug 11. This ultrasound fluoroscope 1
The ultrasonic transducer I9 is attached to the tip of the reactor vessel 9, and a reflecting plate 20 is provided on the inner surface of the reactor vessel 9 facing the ultrasonic transducer 19. In addition,
In the figure, reference numeral 2I indicates the free liquid level of liquid sodium, and 22 indicates the cover scum space.

The above-mentioned ultrasonic fluoroscope 18 observes the floating state of the handling head of the fuel assembly in order to check whether each fuel assembly in the core 13 is loaded in the correct position.

In addition, when replacing the fuel assembly, etc., use the rotary plug 1.
2 needs to be activated. In this case, if there is an obstacle between the fuel assembly and the upper core mechanism 17 that interferes with the operation of the rotating plug 12, the fuel assembly will be damaged or cracked. The presence or absence of this obstacle is determined based on the round trip time or direction of the ultrasonic waves.

(Problem to be Solved by the Invention) If the ultrasonic transducer 19 and the liquid sodium 15 in which it is immersed have poor wettability and lack good adhesion, the above-mentioned ultrasonic fluoroscope 18 or the gap between the rotating plug I2 It goes without saying that monitoring performance will result in a decrease in performance. So liquid sodium! In order to maintain good adhesion between the ultrasonic transducer 5 and the ultrasonic transducer 5, the outer surface of the metal case 1 housing the ultrasonic transducer 3 must be completely wetted with the liquid sodium 15.

However, the temperature of liquid sodium 15 is low at about 20
When the temperature is 0° C. or lower, it is difficult to establish complete wettability in a short period of time. In addition, high purity liquid sodium 15
Even use ultrasonic transducers! Impurities adhere or a thin gas layer is formed on the surface of the metal case 1 of 9. This results in insufficient wettability between the surface of the metal case 1 and the liquid sodium 15, resulting in incomplete adhesion between the two. For this reason, the accuracy of measured values during inspection or observation will be adversely affected. Furthermore, in a fast breeder reactor, since the ultrasonic fluoroscope I8 is installed for a short period of time, such as when replacing a fuel assembly, When the temperature of the liquid sodium 15 is low, impurities or an extremely thin gas layer are formed as described above. Therefore, there are problems in that the transmitted power or energy is not only absorbed by the gas layer and not propagated into the liquid sodium, but also not received.

The present invention has been made in order to solve the above-mentioned problems, and the present invention has been made in such a way that the surface of the metal case of an ultrasonic transducer can always exhibit wettability with liquid sodium in a short period of time in a normal state and maintain good adhesion. An object of the present invention is to provide a method for assembling an ultrasonic transducer.

[Structure of the Invention] (Means for Solving the Problems) The present invention includes a surface treatment process in which a metal case is heated in an inert gas to remove surface dirt, and a metal case treated in this surface treatment process. A step of immersing the metal case in a high-temperature pure liquid metal and solidifying it to form the metal film, and immersing the metal case and the metal case treated in the metal film forming step in a liquid with excellent leakage properties to form a liquid film. A liquid film forming step in which the metal case treated in this liquid film forming step is immersed in a liquid that is solid at room temperature and becomes liquid when heated to form a film of a material solidified at room temperature on the liquid film surface. and a step of incorporating an ultrasonic vibrator into a metal case after forming this room-temperature solidified material film.

(Function) The surface treatment process removes dirt such as chips, oil, and rust from the surface of the finished metal case, and also improves the adhesion between the liquid metal in which the metal case is immersed and the metal that is easily compatible with it. do.

In the metal film forming step, a metal film is formed that completely wets the liquid metal.

In the liquid film forming step, a liquid film is formed to prevent the metal film from being oxidized when exposed to air.

The room-temperature solidified film forming step is for protecting the liquid film with a room-temperature solidified film, and the solidified film becomes a liquid state when heated.

The ultrasonic transducer assembling step is to assemble an ultrasonic transducer into the inner bottom surface of the metal case on which the metal film, liquid film, and room-temperature solidified film have been formed through the above-mentioned processing steps, in the same manner as in the conventional example.

When the ultrasonic transducer assembled in this way is used in liquid metal, the metal case has already formed a metal film that easily leaks with the liquid metal, so the leakage with the liquid metal is good, and the ultrasonic wave is Transmission and reception occur quickly.

(Embodiment) An embodiment of the method for assembling an ultrasonic transducer according to the present invention will be described with reference to FIGS. 1 and 2.

In FIG. 1, in the surface treatment step 23, the metal case 1 shown in FIG. 3 is machined and surface-finished, and then the surface is cleaned of cutting oil, chips, rust, etc. with an organic solvent, acid, etc. do. In the metal film forming step 24, a metal film 28 of liquid metal, such as liquid sodium, is deposited on the lower surface of the metal case 1, as shown in FIG. This step 24 is carried out by immersing the metal case 1 in a pot containing liquid sodium in an inert gas atmosphere.

In the metal film forming step 24, after cooling in liquid sodium, the metal case 1 and the metal case 1 whose surface has been treated in the step 23 are immersed in a liquid with excellent leakage properties, such as silicone oil, in an inert atmosphere. Liquid film forming step 25 of depositing a silicone oil liquid film 29 on the outer surface of the case
I do.

Next, in the room temperature solidified film forming step 26, the metal case 1 on which the liquid film 29 has been formed is solidified at room temperature, and cooled by immersing it in a container containing a substance that becomes liquid at the temperature of the liquid metal, such as paraffin. A room-temperature solidified film 3G is formed. That is, the surface of the liquid film 29 is covered with a paraffin film.

Finally, as shown in FIG. 2, a metal film 28. As shown in FIG.
An ultrasonic transducer incorporating step 27 is performed to incorporate the ultrasonic transducer. Since this step 27 can be performed in the same manner as in the conventional example, the method will be omitted.

According to the embodiment described above, the lower surface of the metal case can be kept clean without being exposed to air. Therefore, when used in an ultrasonic fluoroscope in a fast breeder reactor, when loaded into liquid sodium, the room temperature solidified film 30 and liquid film 29 are immediately melted and dispersed due to the temperature of the liquid sodium, and the metal film 28 is exposed. Since this metal film 28 has the same or similar properties as liquid sodium, it is easily compatible with liquid sodium and has excellent leakability with liquid sodium. Therefore, there are no holes or gaps between the bottom of the metal case 1 and the liquid sodium.
Transmission and reception of the ultrasonic transducer 3 can be performed promptly without error.

[Effects of the Invention] According to the present invention, leakage with liquid metal is improved;
The time for the ultrasonic transducer to leak with liquid metal is reduced. Therefore, when used as an ultrasonic fluoroscope, reliability is improved along with quick response, and work time for ultrasonic measurement, fuel exchange, etc. can be shortened, and operating time can be extended.

[Brief explanation of drawings]

FIG. 1 is a process diagram showing an example of the method for assembling an ultrasonic transducer according to the present invention, FIG. 2 is a longitudinal sectional view of a metal case processed in the process of FIG. 1, and FIGS. 3 and 4 are conventional FIG. 3 is a vertical cross-sectional view of an ultrasonic transducer, and FIG. 4 is a schematic vertical cross-sectional view of a fast breeder reactor. 1... Metal case 2... Cover 3... Ultrasonic vibrator 4... Electrode 5... Silver paste 6... Seal connector 7... Electric wire 8... M1 cable 9...・Reactor vessel O...Top opening! ... Fixed plug 2 ... Rotating plug 3 ... Core 4 ... Inlet pipe 5 ... Liquid sodium 6 ... Outlet pipe 7 ... Core upper mechanism ... Ultrasonic fluoroscope 9 ... ... Ultrasonic transducer 20 ... Reflection plate 21 ... Free liquid surface of liquid sodium 22 ... Cover gas space 23 ... Surface treatment step 24 ... Metal film forming step 25 ... Liquid film formation Step 26...Room temperature solidification film formation step 27...Ultrasonic transducer installation step 28...Metal film 29...Liquid film 30...Room temperature solidification film (8733) Agent Patent attorney Sho Inomata Akira (and others)
1 person) Kaya 2 Illustration area] 5th close

Claims (1)

[Claims] A surface treatment step in which the metal case is heated in an inert gas to remove surface dirt, and the metal case treated in this surface treatment step is immersed in high-temperature pure liquid metal to solidify and form the metal film. a liquid film forming step in which the metal case treated in this metal film forming step is immersed in a liquid with excellent leakage properties to form a liquid film; immersing the metal case in a liquid that is solid at room temperature and becomes liquid when heated to form a film of a material that solidifies at room temperature on the surface of the liquid film; A method for assembling an ultrasonic transducer, comprising the step of incorporating an ultrasonic transducer.