JP2937538B2 - Ultrasonic transducer for reactor fluoroscopy. - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic transducer for nuclear reactor fluoroscopy, and more particularly to an ultrasonic transducer for nuclear reactor fluoroscopy immersed in liquid metal sodium filled in a fast breeder reactor and illuminating the inside of a vessel. Related to sonic transducers.

[0002]

2. Description of the Related Art In a fast breeder reactor, a see-through device is installed for see-through observation of positions, shapes, and the like of various devices in the reactor vessel. Since this see-through device is immersed in high-temperature liquid metallic sodium filled in a reactor vessel, high-temperature ultrasonic transducers having excellent corrosion resistance are widely used.

FIG. 3 shows a fast breeder reactor equipped with such a high-temperature ultrasonic transducer. The upper opening of a reactor vessel 1 is closed by a fixed plug 2 and a rotary plug 3. A core 4 is disposed in the reactor core 1 and includes a plurality of fuel assemblies and core components 5 such as control rods. The liquid metal sodium 7 flowing from the inlet pipe 6 flows through the reactor core 4, takes heat, and flows out of the outlet pipe 8. The rotary plug 3 has a core upper mechanism 9
Penetrates, and an ultrasonic fluoroscope 10 penetrates the fixed plug 2. A high-temperature ultrasonic transducer 11 is attached to the tip of the ultrasonic transilluminator 10. The ultrasonic transducer 11 is immersed in the liquid metal sodium 7 and emits ultrasonic waves in the direction of arrow 12 to observe the lifting state of the handling head of the fuel assembly and to determine whether the fuel assembly is loaded at the correct position. Inspect

In order to replace the fuel assembly, it is necessary to operate the rotary plug 3. At this time, an obstacle between the fuel assembly and the upper core mechanism 9 which hinders the operation of the rotary plug 3 is required. In the presence of the fuel assembly, the fuel assembly is damaged or cracked. Therefore, the ultrasonic transducer 11 determines the presence or absence of the obstacle based on the reciprocating time or direction of the ultrasonic wave.

FIG. 4 shows an ultrasonic transducer 1 for high temperature.
1 shows a structure, in which a cover 14 is attached to an upper opening of a cylindrical stainless steel metal case 13 by welding to seal the inside of the metal case 13. A disk-shaped high-temperature ultrasonic vibrator 15 made of lithium niobate is bonded to the inner surface of the bottom portion 13a of the metal case 13 by a paste 16 as a bonding material. The ultrasonic transducer 15 has a Curie point of 1200 ° C., an electromechanical coupling coefficient Kt of 0.17, a frequency of 2.5 MHz, and a pulse width of about 50 μsec. An electric wire 18 covered with a silicone rubber tube is connected to the electrode 17 of the ultrasonic vibrator 15, and the electric wire 18 is connected to the inorganic insulated cable 20 by a hermetic type seal connector 19 penetrating the cover 14.

The ultrasonic vibrator 15 is an inorganic insulated cable 20
When a predetermined voltage is applied through the wire 18 and the electric wire 18, an ultrasonic wave having a frequency of 2.5 MHz and a pulse width of about 50 μs is oscillated, and the ultrasonic wave is emitted through the bottom 13 a of the metal case 13. Will be sent out.

However, the ultrasonic transducer 11 has poor wettability between the outer surface of the metal case 13 made of stainless steel and the liquid metal sodium 7, so that impurities adhere to the outer surface of the metal case 13 or a thin gas layer is formed. It is formed. When such an impurity or a thin gas layer is formed on the bottom portion 13a of the metal case 13 which is the ultrasonic wave transmitting surface, the power of the ultrasonic wave, that is, the energy is absorbed by the impurity or the gas layer, and it is difficult to propagate the liquid metal sodium 7. Or the reception becomes difficult. Such poor wettability is remarkable when the temperature of the liquid metal sodium 7 is about 200 ° C. or lower, and it has been difficult to establish complete wettability in a short time.

Therefore, as shown in FIG. 5, a coating layer 21 of gold, nickel or the like is formed on the bottom 1 of the metal case 13.
3a, so that the wettability between the metal case bottom 13a and the liquid metal sodium 7 is improved.

[0009]

However, in the conventional ultrasonic transducer 11, the coating layer 21 of gold, nickel, or the like is only coated on the bottom 13a of the metal case. It elutes in the liquid metal sodium 7. Therefore, when the ultrasonic transducer 11 is once pulled up from the liquid metal sodium 7 and immersed again, there is a problem that the coating layer 21 of gold, nickel or the like must be formed again before the immersion.

It is an object of the present invention to provide an ultrasonic transducer for nuclear reactor fluoroscopy that can maintain good wettability over a long period of time even when repeatedly immersed in liquid metal sodium.

[0011]

In order to achieve this object, the present invention provides a metal case immersed in liquid metal sodium filled in a nuclear reactor, and a liquid case accommodated in the metal case. An ultrasonic transducer for transmitting ultrasonic waves to the liquid metal sodium through a wall of the metal case immersed in sodium, the ultrasonic transducer for reactor fluoroscopy, wherein the wall of the metal case is
A metal having good wettability with the liquid metal sodium is ion-implanted into a surface in contact with the liquid metal sodium.

In this configuration, the metal having good wettability with the liquid metal sodium is preferably gold or nickel.

[0013]

[Function] Since the metal case immersed in the liquid metal sodium is ion-implanted with a metal having good wettability with the liquid metal sodium, the metal case comes into close contact with the liquid metal sodium in a short time, generating a gas layer and impurities. Is sufficiently suppressed.

Even if the ion-implanted metal with good wettability elutes from the surface of the metal case into the liquid metal sodium, the metal with good ion-implantability which has been ion-implanted inside appears on the surface. The case surface is always kept in a state of good wettability with the liquid metal sodium.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an ultrasonic transducer for see-through of a nuclear reactor according to the present invention will be described below with reference to FIGS. 1 and 2 in which the same parts as those in FIGS. Will be explained.

In FIG. 1, a cover 14 is attached to the upper opening of a cylindrical stainless steel metal case 13 by welding to seal the inside of the metal case 13. A disc-shaped high-temperature ultrasonic vibrator 15 made of lithium niobate is joined to the inner surface of the bottom 13 a of the metal case 13 by a silver paste 16. Ultrasonic transducer 15
The electrode 17 is connected to an electric wire 18 covered with a silicone rubber tube, and the electric wire 18 is connected to an inorganic insulated cable 20 by a hermetic type seal connector 19 penetrating the cover 14.

An ion implantation layer 22 of a metal having good wettability with liquid metal sodium such as gold or nickel is formed on the surface of the bottom portion 13a of the metal case 1 to which the ultrasonic transducer 15 is joined. As shown in FIG. 2, the ion-implanted layer 22 is formed by ion-implanting gold, nickel or the like into the bottom portion 13a of the metal case 13 from the surface thereof, that is, the surface in contact with the liquid metal sodium, to a predetermined depth.

Next, the operation of this embodiment will be described.

The ion implanted layer 22 of the metal case 13 immersed in the liquid metal sodium adheres to the liquid metal sodium in a short time because a metal having good wettability with the liquid metal sodium is ion-implanted. Therefore, the metal case 1
The generation of a gas layer and impurities on the surface of the bottom 13a of the third member 3 is prevented, and the ultrasonic transducer 11 can reliably transmit and receive ultrasonic waves into the liquid metal sodium.

Further, even if the ion-implanted metal such as gold or nickel is eluted from the surface of the metal case into the liquid metal sodium, the metal such as gold or nickel which has been ion-implanted further appears on the surface. The metal case surface is always maintained in a state of good wettability with liquid metal sodium. Therefore, even if the ultrasonic transducer 11 is pulled out of the liquid metal sodium, or if the ultrasonic transducer 11 is immersed again in the liquid metal sodium as it is, good wettability with the liquid metal sodium can be obtained.

[0021]

As is apparent from the above description, according to the present invention, the metal case wall has a short surface because the surface in contact with the liquid metal sodium is ion-implanted with a metal having good wettability with the liquid metal sodium. In close contact with the liquid metal sodium in a short time, the generation of gas layers and impurities can be sufficiently suppressed, and even if a metal with good wettability elutes into the liquid metal sodium from the surface of the metal case, ions are implanted further inside. Because the good wettability metal that has been exposed appears on the surface,
The metal case surface is always kept in a state of good wettability with the liquid metal sodium. Therefore, the ultrasonic transducer of the present invention can be quickly started after being immersed in liquid metal sodium, and the reliability is improved.

Further, even if the ultrasonic transducer is pulled out of the liquid metal sodium, the ultrasonic transducer can be immersed again in the liquid metal sodium, so that the time required for the ultrasonic fluoroscopy operation can be shortened, and the operating time of the reactor can be extended. be able to.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing an embodiment of an ultrasonic transducer for nuclear reactor fluoroscopy according to the present invention.

FIG. 2 is an enlarged sectional view showing a main part of FIG. 1;

FIG. 3 is a cross-sectional view showing a general fast breeder reactor equipped with an ultrasonic transducer.

FIG. 4 is a longitudinal sectional view showing a conventional ultrasonic transducer.

FIG. 5 is an enlarged sectional view showing the bottom of a conventional ultrasonic transducer.

[Explanation of symbols]

 7 Liquid Metal Sodium 11 Ultrasonic Transducer 13 Metal Case 13a Bottom of Metal Case 15 Ultrasonic Vibrator 22 Ion Implantation Layer

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-3-51708 (JP, A) JP-A-2-129868 (JP, U) JP-A-2-118881 (JP, U) (58) Field (Int.Cl. ⁶ , DB name) G01B 17/00 G01N 29/08 507 G01N 29/24 G21C 17/08 GDF

Claims (2)

(57) [Claims] An ultrasonic wave is transmitted through a metal case immersed in liquid metal sodium filled in a nuclear reactor and a wall of the metal case housed in the metal case and immersed in the liquid metal sodium. An ultrasonic transducer for nuclear reactor fluoroscopy comprising an ultrasonic transducer for sending to the liquid metal sodium, wherein the wall of the metal case has a good wettability with the liquid metal sodium on a surface in contact with the liquid metal sodium. An ultrasonic transducer for nuclear reactor fluoroscopy, wherein a metal is ion-implanted. 2. The ultrasonic transducer according to claim 1, wherein the metal having good wettability with the liquid metal sodium is gold or nickel.