KR20220047093A - Bubble detection apparatus - Google Patents

Abstract

One embodiment of the present invention provides a bubble detection device capable of measuring the size distribution and porosity of argon bubbles dissolved inside the liquid metal coolant in a nuclear reactor using a liquid metal coolant and monitoring the bubbles all times during operation of the nuclear reactor. The bubble detection device according to one embodiment of the present invention includes a bubble detection waveguide sensor module installed on top of a head of a nuclear reactor using liquid metal coolant, and having one end exposed to the outside and the other end in contact with the liquid metal coolant, wherein leaky ultrasound is emitted into the liquid metal coolant and a high-frequency ultrasonic beam and a low-frequency ultrasonic beam are focused on the bubble detection measurement area, to measure the bubble porosity to measure the non-linear resonance phenomenon caused by air bubbles, thereby measuring the cell size distribution and porosity of the target gas dissolved inside the liquid metal coolant.

Description

Bubble detection device {BUBBLE DETECTION APPARATUS}

The present invention relates to a bubble detection device.

To detect bubbles in sodium in a liquid metal furnace, an optical method cannot be used due to the opacity of sodium, so a method using ultrasound is being applied. When ultrasonic waves are incident on the bubble, non-linear vibration occurs due to the resonance of the bubble and has a characteristic of generating 2nd and 3rd harmonic components with respect to the driving frequency. This non-linear vibration characteristic uses an immersion ultrasonic transducer to continuously frequency sweep a pumping pulse having a low frequency while transmitting a high-frequency pulse. A low-frequency and high-frequency pulse synthesis technique, which measures the excitation frequency of a low-frequency pulse to measure the bubble size distribution and porosity, is widely applied.

Conventional immersion ultrasonic sensors used to detect bubbles in sodium in liquid metal cannot be used for a long time in a high-temperature, high-radiation environment. Therefore, there is a problem in that it is not possible to constantly monitor the bubbles inside the sodium coolant during reactor operation.

Most of the immersion-type ultrasonic sensors can be installed only above the sodium level and are difficult to install in the upper part of the core and main parts of the internal structure, so there is a problem in that the area that can measure the argon bubble size and porosity is limited.

As a related prior art, US Patent No. 4,112,735 discloses "Detection of bubbles in a liquid".

US Patent 4,112,735

One embodiment of the present invention is to provide a bubble detection device capable of measuring the size distribution and porosity of argon bubbles dissolved in the liquid metal coolant in a nuclear reactor using a liquid metal coolant, and monitoring at all times during reactor operation.

In addition to the above problems, the embodiment according to the present invention may be used to achieve other problems not specifically mentioned.

A bubble detection device according to an embodiment of the present invention is installed on the head of a nuclear reactor using a liquid metal coolant, one end of which is exposed to the outside, and the other end includes a bubble detection waveguide sensor module in contact with the liquid metal coolant, The high-frequency ultrasound beam and low-frequency ultrasound beam are focused on the bubble detection measurement area to emit leaking ultrasound into the liquid metal coolant and measure the bubble porosity to measure the non-linear resonance caused by the bubbles. Measure the bubble size distribution and porosity of the gas to be measured.

An embodiment of the present invention is provided with a bubble detection waveguide sensor module to measure the size distribution and porosity of argon bubbles dissolved in the liquid metal coolant in a nuclear reactor using a liquid metal coolant, and to monitor the effect at all times during reactor operation there is

1 is a view showing a state in which a bubble detection device according to an embodiment of the present invention is installed on the upper part of a reactor head of a liquid metal furnace.
2 is a conceptual diagram of a bubble detection apparatus according to an embodiment of the present invention.
3 is a configuration diagram of a bubble detection ultrasonic testing apparatus to which a high-frequency and low-frequency ultrasonic synthesis technique is applied.
4 is a view showing the ultrasonic beam radiation of the bubble detection apparatus according to an embodiment of the present invention.
5 is a view showing the phase velocity of the A0 plate wave in the waveguide sensor.
6 is a view showing an ultrasonic scattering signal and a frequency spectrum by bubbles measured by the bubble detection apparatus according to an embodiment of the present invention.

With reference to the accompanying drawings, the embodiments of the present invention will be described in detail so that those of ordinary skill in the art to which the present invention pertains can easily implement them. The present invention may be embodied in many different forms and is not limited to the embodiments described herein. In order to clearly explain the present invention in the drawings, parts irrelevant to the description are omitted, and the same reference numerals are used for the same or similar components throughout the specification. In addition, in the case of a well-known known technology, a detailed description thereof will be omitted.

Throughout the specification, when a part "includes" a certain element, it means that other elements may be further included, rather than excluding other elements, unless otherwise stated.

Hereinafter, the bubble detection apparatus will be described in detail with reference to the drawings.

1 is a view showing a state in which a bubble detection apparatus according to an embodiment of the present invention is installed on the upper part of a reactor head of a liquid metal furnace, and FIG. 2 is a conceptual diagram of a bubble detection apparatus according to an embodiment of the present invention. 3 is a block diagram of a bubble detection ultrasound testing apparatus to which a high-frequency and low-frequency ultrasound synthesis technique is applied, and FIG. 4 is a diagram illustrating ultrasound beam radiation of the bubble detection apparatus according to an embodiment of the present invention. 1 to 4 , the bubble detection device according to an embodiment of the present invention is installed above the head 10 of a nuclear reactor using a liquid metal coolant so that one end is exposed to the outside, and the other end is applied to the liquid metal coolant. It may include a bubble detection waveguide sensor module 100 in contact. Reference numeral 20 denotes a core, and 30 denotes a nuclear fuel exchange unit. The bubble detection waveguide sensor module 100 emits a leaking ultrasound into the liquid metal coolant and focuses a high-frequency ultrasound beam and a low-frequency ultrasound beam on the bubble detection measurement area to measure the bubble porosity, thereby preventing the nonlinear resonance caused by the bubble. By measuring, it is possible to measure the bubble size distribution and porosity of the gas to be measured dissolved inside the liquid metal coolant. The bubble detection waveguide sensor module 100 may be installed above the head of the nuclear reactor as shown in FIG. 1 . Here, the reactor includes a liquid metal furnace using a liquid metal coolant. The liquid metal may include sodium. Accordingly, the liquid metal coolant may include a liquid sodium coolant. By using the bubble detection waveguide sensor module 100, it is easy to measure the bubble porosity of the gas to be measured dissolved in the liquid metal coolant in the core part of the liquid metal furnace, the internal structure, and the part that is difficult to access of the main equipment. can do. Here, the gas to be measured may include argon gas.

The bubble detection waveguide sensor module 100 may include three waveguide sensors and a waveguide sensor module support unit 140 as shown in FIG. 2 . Here, the three waveguide sensors are a low-frequency pump waveguide sensor 110, a high-frequency transmission waveguide sensor unit 120, and a high-frequency transmission waveguide sensor 110 that are spaced apart from each other at a set interval in the circumferential direction around the bubble detection measurement area. It may include a reception waveguide sensor unit 130 . The high-frequency transmission waveguide sensor unit 120 and the high-frequency reception waveguide sensor unit 130 may be disposed such that opposite surfaces of the ultrasound beam emitting unit have a set angle. Here, the set angle may include 90 degrees. The low-frequency pump waveguide sensor unit 110 may be disposed on the opposite surface where the high-frequency transmission waveguide sensor unit 120 and the high-frequency reception waveguide sensor unit 130 are positioned.

The low-frequency pump waveguide sensor unit 110, the high-frequency transmission waveguide sensor unit 120, and the high-frequency reception waveguide sensor unit 130 each include a waveguide, a wedge, an ultrasonic transducer, a guide tube, and an ultrasonic beam emitting unit. may include The wedge may change the mode of the ultrasonic signal received from the ultrasonic generator. The waveguide is formed long in the longitudinal direction, and one end is connected to the wedge and can guide the ultrasonic signal transmitted and received through the other end. At the other end of the waveguide, the guide tube may be cut at a preset angle to expose one surface of the waveguide to the inside of the liquid metal coolant to form an ultrasonic beam emitting part. The waveguide may be formed in a plate shape made of a stainless steel material having a thin thickness and a long length. One end of the waveguide may be connected to a wedge positioned outside the reactor vessel, and the other end of the waveguide may be positioned inside the reactor vessel. A guide tube may be provided outside the waveguide. The guide tube is provided in a shape surrounding the outside of the waveguide, and can protect the waveguide from high-temperature, high-radiation liquid metal. The guide tube may be provided to be spaced apart from the surface of the waveguide by a predetermined distance. The guide tube is spaced apart from the waveguide to prevent the propagation energy of the plate wave from escaping into the liquid metal.

Referring to FIG. 2 , the high-frequency transmission waveguide sensor unit 120 includes a waveguide 122 for high-frequency transmission, an ultrasonic transducer 124 for high-frequency transmission, a wedge 126 for high-frequency transmission, and a guide tube 128 for high-frequency transmission. ), and may include an ultrasonic beam emitting unit 127 for high-frequency transmission. Since this common configuration is also applied to the low-frequency pump waveguide sensor unit 110 and the high-frequency reception waveguide sensor unit 130, respectively, overlapping descriptions and reference numbers will be omitted. For reference, opposite surfaces of the ultrasonic beam emitter 127 for high frequency transmission and the ultrasonic beam emitter 137 for high frequency reception in the ultrasonic beam emitter may be disposed at 90 degrees. And the ultrasonic beam emitter 117 for the low frequency pump is disposed on the opposite side of the ultrasonic beam emitter 127 for high frequency transmission and the ultrasonic beam emitter 137 for high frequency reception so that each ultrasonic beam emitter is directed toward the bubble detection measurement area. can be located.

As described above, the bubble detection waveguide sensor module 100 is a waveguide sensor that remotely transmits and receives ultrasonic signals using a plate-shaped waveguide (WG) with an ultrasonic sensor outside in an extreme nuclear reactor environment of high temperature and high radiation. It is permanently installed inside the high-temperature liquid metal coolant and an ultrasonic transducer is installed outside the reactor to convert electrical energy having a frequency range of the ultrasonic band into mechanical vibration. It can be monitored at all times. For example, when a liquid metal such as sodium is used as a coolant, the bubble size distribution and porosity of argon gas included in the liquid sodium coolant may be measured.

3, in the bubble detection waveguide sensor module 100, the ultrasonic transducer 114 of the low-frequency pump waveguide sensor unit 110 and the ultrasonic transducer 124 of the high-frequency transmission waveguide sensor unit 120 are Each of the multi-channel waveform generator (Function Generator) and the gate amplifier (Gated Amplifier) connected to the control unit (PC) can be controlled. In addition, a broadband receiver is connected to the ultrasonic transducer 134 of the high frequency reception waveguide sensor unit 130, and the received ultrasonic signal is transmitted from the controller (PC) through an analog-to-digital converter (A/D Board). can be collected.

A process of detecting argon gas bubbles contained in sodium coolant using the bubble detection waveguide sensor module 100 according to an embodiment of the present invention will be described with reference to FIGS. 1 to 4 .

First, assuming a liquid metal furnace using sodium as a coolant, the argon cover gas above the primary liquid metal coolant stored in the reactor vessel flows into sodium through the sodium free liquid level and exists as argon bubbles. Argon bubbles introduced into sodium not only increase the nuclear reactivity of the core and reduce the heat transfer efficiency of the liquid metal coolant, but also disturb the signal of the instrument, which can cause problems in the safe operation of liquid metal and instrumentation monitoring.

A bubble detection waveguide sensor module 100 that remotely transmits and receives ultrasonic signals using a plate-shaped waveguide (WG) with an ultrasonic sensor outside in a high-temperature, high-radiation, or extreme sodium environment that is difficult to access directly, such as a liquid metal furnace. ) is permanently installed inside the high-temperature sodium coolant and an ultrasonic transducer is installed outside the reactor to detect argon gas bubbles contained in the sodium coolant and to monitor the bubble porosity at all times. That is, by using the bubble detection waveguide sensor module 100 to measure the bubble size distribution and porosity of the argon gas dissolved in the sodium coolant of the liquid metal furnace, it is possible to monitor it at all times during the operation of the nuclear reactor. In addition, by applying a plate-type waveguide sensor to the detection of air bubbles in argon gas contained in sodium coolant, it can be applied without limitation in service life, and the ultrasonic transducer can be replaced and applied according to the frequency of use according to the measurement range of the bubble size distribution. .

Meanwhile, the bubble detection waveguide sensor module 100 assumes a state in which three waveguide sensors are arranged in a circumferential direction with respect to a bubble detection measurement point as shown in FIG. 4 . For example, the high-frequency transmission/reception waveguide sensor may be disposed so that the radiation surface of the ultrasonic beam has an angle of 90 degrees, and the low-frequency pump waveguide sensor unit 110 may be disposed on the opposite side of the high-frequency transmission/reception waveguide sensor. In this way, the plate waveguide sensor is arranged in the form of an array like an immersion type ultrasonic sensor, and while continuously excitation of low-frequency ultrasonic pulses in the range of 0.1 MHz to 0.5 MHz, high-frequency ultrasonic waves of 2.25 MHz are transmitted and received ultrasonic signals of 2.25 MHz are received. can

When the zero-order antisymmetric A0 plate wave generated by injecting the ultrasonic pulse into the waveguide is in contact with the liquid, the mode is converted into a longitudinal wave into the liquid, and may be radiated as shown in FIG. 4 .

5 is a view showing the phase velocity of the A0 plate wave in the waveguide sensor. The ultrasonic signal generated from the outside may be transmitted to the plate-shaped waveguide through the wedge. When an ultrasonic signal having a specific frequency is transmitted to a plate-shaped waveguide through a wedge, the ultrasonic signal may be converted into a plate-wave mode. The bubble size and porosity of the gas to be measured can be measured using the plate wave propagating along the longitudinal direction of the waveguide. Here, a plate wave (lamb wave) refers to a wave propagating in a thin plate-shaped solid, and may be divided into a symmetric mode (S-Mode) and an anti-symmetric mode (A-Mode) according to the propagation method. In the case of the symmetric mode, the component of the wave vibrating in the traveling direction of the plate wave may be displayed symmetrically with respect to the thickness center line of the plate. On the other hand, in the case of the antisymmetric mode, the component of the wave vibrating in the propagation direction of the plate wave may be displayed asymmetrically with respect to the thickness center line of the plate. In the waveguide sensor unit according to the embodiment of the present invention, the 0th order antisymmetric plate wave A0 may be used. The plate wave may propagate along the waveguide in the longitudinal direction of the waveguide. At this time, the ultrasonic beam radiation angle θ may be calculated by Equation 1 according to the longitudinal wave velocity V _L and the plate wave phase velocity C _p in the sodium coolant.

[Equation 1]

sinθ = V _L / C _p

Here, the phase velocity (C _p ) of the plate wave can be expressed as a function of the ultrasonic frequency (f) and the thickness (d) of the waveguide. The ultrasonic beam radiation angle θ may also be expressed as a function of the ultrasonic frequency f and the thickness d of the waveguide. Accordingly, when the ultrasonic frequency f is changed or the thickness d of the waveguide is changed, the ultrasonic beam radiation angle θ may also be changed.

6 is a diagram illustrating an ultrasonic scattering signal and a frequency spectrum by bubbles measured by the bubble detection apparatus according to an embodiment of the present invention. Referring to FIG. 6 , the bubble size is calculated by measuring the incident frequency of the low-frequency pulse at which the second and third harmonics are generated by the resonance mode of the bubble in the frequency spectrum, and the frequency of occurrence at each resonance frequency for a specific time is measured. Thus, the bubble size distribution can be obtained, and the bubble porosity can be measured from this.

As described above, using the bubble detection waveguide sensor module 100 according to the embodiment of the present invention, it detects whether argon bubbles are generated inside the high-temperature liquid metal coolant during the operation of the liquid metal reactor, and the bubble size and bubble porosity can be measured at all times and continuous monitoring is possible. And since the ultrasonic transducer of the waveguide sensor is installed outside the reactor head, it can be used semi-permanently. In addition, since the transducer is easily replaceable, the operating frequency can be changed, thereby expanding the measurement range of the bubble size distribution.

Although preferred embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements by those skilled in the art using the basic concept of the present invention as defined in the following claims are also provided. is within the scope of the

100 ; Bubble detection waveguide sensor module
110 ; Low frequency pump wave guide sensor unit
120 ; High-frequency transmission waveguide sensor unit
130 ; High frequency reception waveguide sensor unit

Claims (12)

It is installed on the head of a nuclear reactor using a liquid metal coolant, one end is exposed to the outside, and the other end includes a bubble detection waveguide sensor module in contact with the liquid metal coolant,
A high-frequency ultrasound beam and a low-frequency ultrasound beam are focused on the bubble detection measurement area to measure the bubble porosity by emitting leakage ultrasound into the liquid metal coolant, and then measuring the nonlinear resonance phenomenon caused by the bubble to be inside the liquid metal coolant. A bubble detector that measures the bubble size distribution and porosity of the dissolved gas to be measured. In claim 1,
The bubble detection waveguide sensor module is
a wedge for mode conversion of the ultrasonic signal received from the ultrasonic generator;
A wave guide formed long in the longitudinal direction, one end connected to the wedge and guiding the ultrasonic signal transmitted and received through the other end
A bubble detection device comprising a. In claim 2,
The bubble detection device further comprising a guide tube formed in a shape surrounding the outside of the waveguide to protect the waveguide from the liquid metal. In claim 3,
The other end of the waveguide is cut in the guide tube at a preset angle to expose one surface of the waveguide to the inside of the liquid metal coolant to form an ultrasonic beam emitting part. In claim 3,
The waveguide is a bubble detection device formed in a plate shape. In claim 5,
A bubble detection device for measuring a bubble size and a porosity of the gas to be measured using a plate wave propagating along the longitudinal direction of the waveguide. In claim 5,
The wave guide is a bubble detection device comprising a stainless steel material. In claim 5,
The bubble detection waveguide sensor module is
A bubble detection device including a low-frequency pump waveguide sensor unit, a high-frequency transmission waveguide sensor unit, and a high-frequency reception waveguide sensor unit spaced apart from each other at a set interval in a circumferential direction around a bubble detection measurement area. In claim 8,
The high-frequency transmission waveguide sensor unit and the high-frequency reception waveguide sensor unit are disposed so that opposing surfaces of the ultrasound beam emitting unit have a set angle. In claim 9,
A bubble detection device for disposing the low-frequency pump waveguide sensor unit on the opposite side where the high-frequency transmission waveguide sensor unit and the high-frequency reception waveguide sensor unit are located. In claim 8,
A multi-channel waveform generator and a gate amplifier are respectively connected to the ultrasonic transducer of the low-frequency pump waveguide sensor unit and the ultrasonic transducer of the high-frequency transmission waveguide sensor unit. In claim 11,
A bubble detection device in which a broadband reception amplifier is connected to the ultrasonic transducer of the high frequency reception waveguide sensor unit.

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