KR102160053B1 - Mobile inspection device for measuring thickness of containment liner plates - Google Patents

Abstract

The present invention relates to a mobile inspection device for measuring the thickness of a liner plate of a nuclear containment building. More specifically, the present invention provides a mobile inspection device for measuring the thickness of a liner plate of a nuclear containment building, which comprises: a moving unit attached to a containment liner plate (CLP) of the inner surface of a nuclear containment building, and moving along a wall surface of the CLP; a sensor unit for measuring the thickness of the CLP disposed in the moving unit in a non-contact manner; and a gap control unit disposed on the moving unit to constantly maintain a gap between the sensor unit and the CLP. According to the present invention, it is possible to measure the thickness of a liner plate of a nuclear containment building with reliability without being affected by the surface state of a CLP.

Description

Mobile inspection device for measuring the thickness of liner plate of nuclear power plant containment building {MOBILE INSPECTION DEVICE FOR MEASURING THICKNESS OF CONTAINMENT LINER PLATES}

The present invention relates to a mobile inspection device for measuring the thickness of a liner plate of a nuclear power plant containment building. More specifically, the present invention relates to a non-contact mobile inspection device for measuring the thickness of a liner plate of a nuclear power plant containment building.

As shown in FIG. 1, the nuclear power plant 100 includes a containment building 120 that prevents the discharge of radioactive materials in excess of the permitted amount to the atmosphere beyond the managed area in the event of the reactor 110 and the reactor 110 accident. Equipped.

A steel plate structure called a liner plate 121 (hereinafter, referred to as “CLP”) is installed on the inner surface of the containment building 120 shown in FIG. 1. CLP (121) is a part of the structure of the containment building (120), serves as a formwork of concrete when constructing a nuclear reactor, and serves to prevent external leakage of radioactivity in the event of an accident. Recently, a case of corrosion on the back side of the CLP 121 (121') has been discovered in some nuclear power plants, and corrosion sites are detected and repaired at the nuclear power plant site.

For the maintenance work of the CLP 121, it is necessary to detect the area where corrosion has occurred. Corrosion sites on the back side of the CLP can be found through thickness inspection of the CLP 121. In the prior art, for the thickness test of the CLP, it was primarily measured at wide intervals (for example, 5 cm above and below, 30 cm left and right). Furthermore, in the prior art, the area around the area where the thickness is suspected to decrease in the first inspection is inspected at a more dense interval (for example, 2.5 cm above and below, 2 cm left and right) to detect the corroded area.

The conventional CLP thickness inspection has been performed by manual inspection using a piezoelectric ultrasonic transducer. The conventional CLP thickness inspection method has been performed in such a manner that an inspector installs a scaffolding in a containment building to access the inspection site, and directly contacts a transducer at each measurement point to read an indication value. Meanwhile, in order to use such a piezoelectric ultrasonic probe, the inspector must continuously apply a couplant such as water to the measuring point.

As described above, the conventional CLP thickness inspection method has a very low inspection speed (more than thousands of hours per unit 1) because the inspector must prepare a method for directly accessing the inspection site and continuously apply a contact medium to the measurement point. ) Has its drawbacks.

In addition, there is a problem in that the contact medium applied to the measurement point remains on the surface of the CLP or flows to the bottom of the building, affecting the safety of the inspector or damaging the equipment inside the nuclear power plant.

An object of the present invention is to provide an apparatus capable of measuring the thickness of a CLP without a contact medium.

In addition, an object of the present invention is to provide an apparatus capable of measuring the thickness of a CLP without an inspector's access to the measurement site.

In order to achieve the above object, the present invention provides a mobile inspection device for measuring the thickness of a liner plate of a nuclear power plant containment building. The inspection device is a moving unit attached to a containment liner plate (CLP) on the inner surface of a nuclear power plant containment building and configured to move along the wall of the CLP, and non-contact measuring the thickness of the CLP disposed in the moving unit And a gap control unit disposed on the moving unit and maintaining a gap between the sensor unit and the CLP.

In one embodiment, the moving unit is a moving object attached to the CLP to be movable, a remote control unit disposed spaced apart from the moving object to control the movement of the moving object, and disposed on the moving object, It comprises a position recognition unit configured to recognize the position of the moving object.

In one embodiment, the mobile body and the remote control unit may be connected by wire.

In an embodiment, the sensor unit includes a thickness measurement sensor that measures the thickness of the CLP in a non-contact manner, an ultrasonic pulser and receiver that transmits a reference signal to the thickness measurement sensor, and receives a measurement signal from the thickness measurement sensor, and the A signal processing unit for analyzing a signal received from an ultrasonic pulser and a receiver may be provided.

In an embodiment, the thickness measurement sensor may be disposed on the moving body, and the ultrasonic pulser and receiver, and the signal processing unit may be spaced apart from the moving body.

In one embodiment, the gap control unit is disposed on the moving body, a gap measuring unit measuring a gap between the CLP and the moving body, and a gap disposed on the moving body to adjust a gap between the CLP and the moving body It may include a control unit.

In one embodiment, the gap measurement unit measures a gap between the CLP and the moving body in real time while the moving body is moving, and the gap control unit maintains a constant gap between the CLP and the thickness measurement sensor and the CLP. , It is possible to adjust the gap between the CLP and the moving object in real time.

In an embodiment, the thickness measurement sensor may include a coil and a permanent magnet, generate ultrasonic waves in the thickness direction of the CLP, and then receive a signal reflected from the CLP.

According to the present invention, since the thickness of the CLP can be measured in a non-contact method, reliable measurement is possible without being affected by the surface condition of the CLP.

Further, according to the present invention, it does not require access to the contact medium and the inspector to measure the CLP thickness. For this reason, according to the present invention, it is possible to lower the inspection difficulty and shorten the inspection time.

Further, according to the present invention, since the CLP thickness can be continuously measured, it is possible to eliminate the measurement shadow area.

1 is a conceptual diagram showing a cross-section of a liner plate for a nuclear power plant containment building according to the present invention.
2 is a block diagram showing the components of an inspection apparatus according to the present invention.
3 is a conceptual diagram showing an inspection apparatus according to the present invention.
4 is a conceptual diagram showing the principle of an electromagnetic ultrasonic probe, which is a thickness measurement sensor according to the present invention.
5 is a graph showing changes over time of an ultrasonic signal measured on a CLP specimen.
6 is a conceptual diagram showing an embodiment of a thickness measurement sensor according to the present invention.

It should be noted that the technical terms used in the present specification are only used to describe specific embodiments, and are not intended to limit the present invention. In addition, the technical terms used in the present specification should be interpreted as generally understood by those of ordinary skill in the technical field to which the present invention belongs, unless otherwise defined in the present specification, and excessively comprehensive It should not be construed as a human meaning or an excessively reduced meaning. In addition, when a technical term used in the present specification is an incorrect technical term that does not accurately express the spirit of the present invention, it should be replaced with a technical term that can be correctly understood by those skilled in the art. In addition, general terms used in the present invention should be interpreted as defined in the dictionary or according to the context before and after, and should not be interpreted as an excessively reduced meaning.

In addition, the singular expression used in the present specification includes a plurality of expressions unless the context clearly indicates otherwise. In the present application, terms such as "consist of" or "include" should not be construed as necessarily including all of the various elements or various steps described in the specification, and some of the elements or some steps It may not be included, or it should be interpreted that it may further include additional elements or steps.

In addition, terms including ordinal numbers such as first and second used herein may be used to describe various elements, but the elements should not be limited by the terms. These terms are used only for the purpose of distinguishing one component from another component. For example, without departing from the scope of the present invention, a first component may be referred to as a second component, and similarly, a second component may be referred to as a first component.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings, but the same or similar components are assigned the same reference numerals regardless of the reference numerals, and redundant descriptions thereof will be omitted.

In addition, in describing the present invention, when it is determined that a detailed description of a related known technology may obscure the subject matter of the present invention, a detailed description thereof will be omitted. In addition, it should be noted that the accompanying drawings are only for easily understanding the spirit of the present invention and should not be construed as limiting the spirit of the present invention by the accompanying drawings.

Hereinafter, a mobile inspection device (hereinafter, an inspection device) for measuring the thickness of a liner plate of a nuclear power plant containment according to the present invention will be described in detail.

2 is a block diagram showing components of an inspection apparatus according to the present invention, and FIG. 3 is a conceptual diagram showing an inspection apparatus according to the present invention.

The inspection apparatus according to the present invention may largely include a moving unit 210, a sensor unit 220, a gap control unit 230, a display unit 240, and a power supply unit 250. However, the present invention is not limited thereto, and the inspection apparatus according to the present invention may include more or less components than the above-described components.

In addition, each of the units may include at least one component. At least one component included in each of the units does not necessarily need to be disposed in the same physical space, and the components may be spaced apart from each other.

Hereinafter, the above-described components will be described in detail.

The moving unit 210 is a component that changes the position of the inspection device 200 according to the present invention. The moving unit 210 may include a moving body 211, a remote control unit 212, and a location recognition unit 213. The moving body 211, the remote control unit 212, and the location recognition unit 213 need not necessarily be disposed in the same physical space, and some of the elements may be disposed spaced apart from other elements.

First, the moving body 211 will be described. The movable body 211 is made to be movable while attached to the CLP wall. For example, the moving body 211 may be moved while being attached to the CLP wall through a magnet. Meanwhile, components of the inspection device 200 may be disposed on the moving body 211. This will be described later.

Meanwhile, the remote control unit 212 is a component for remotely controlling the moving body 211. The remote control unit 212 may be spaced apart from the moving body 211. The moving body 211 and the remote control unit 212 may be connected through a wire. However, the present invention is not limited thereto, and the remote controller 212 may be configured to control the mobile 211 through wireless communication with the mobile 211. In this case, a wireless communication unit may be provided in each of the mobile body 211 and the remote control unit 212. However, considering that wireless communication with the mobile 211 is not easy outside the nuclear power plant containment building, the mobile 211 and the remote control unit 212 are preferably connected by wire.

Meanwhile, the location recognition unit 213 is configured to recognize a location measured by the thickness measurement sensor 222 to be described later. In one embodiment, the position recognition unit 213 may be formed in the form of an encoder mounted on a drive motor of the moving body 211, and the encoder is based on a position where the moving body 211 is initially attached. The distance the moving object has moved is calculated. However, the location recognition unit 213 is not limited to the encoder type.

Next, the sensor unit 220 will be described. The sensor unit 220 is disposed on the moving body 211 and is configured to measure the thickness of the CLP in a non-contact manner. To this end, the sensor unit 220 includes an ultrasonic pulser/receiver 221, a thickness measurement sensor 222, and a signal processing unit 223.

The ultrasonic pulser/receiver 221 transmits a reference signal to the thickness measurement sensor 222 and receives a measurement signal from the thickness measurement sensor 222. The measurement signal received by the ultrasonic pulser/receiver 221 is transmitted to the signal processing unit 223 and analyzed.

Meanwhile, the thickness measurement sensor 222 is configured to measure the thickness of the CLP in a non-contact manner. The principle and structure of the thickness measurement sensor 222 will be described with reference to FIGS. 4 to 6.

4 is a conceptual diagram showing the principle of an electromagnetic ultrasonic probe, FIG. 5 is a graph showing a change over time of an ultrasonic signal measured on a CLP specimen, and FIG. 6 is a conceptual diagram showing an embodiment of a thickness measurement sensor according to the present invention to be.

Referring to FIG. 4, the thickness measurement sensor according to the present invention measures the thickness of a CLP using the principle of an electromagnetic ultrasonic transducer (EMAT). Specifically, when a coil is raised on the surface of an electric conductor and AC electricity of a frequency f is passed through the coil, an eddy current of the same frequency is generated on the surface of the conductor. At this time, when a magnetic field is applied in a direction perpendicular to the eddy current using a permanent magnet or the like, ultrasonic waves of a frequency f are generated in a direction perpendicular to both the magnetic field and the eddy current in the conductor according to the Lorentz force principle.

In the above-described manner, when ultrasonic waves are generated in the thickness direction of the CLP, the ultrasonic waves are continuously reflected on both surfaces formed in the thickness direction of the CLP. When the reflected signal from the CLP is measured (refer to FIG. 5), the time interval (Δt, the interval between the red circles in FIG. 5) between the reflected signals can be measured. When the time interval is measured, the thickness of the CLP can be calculated according to Equation 1 below.

[Equation 1]

In Equation 1, c is the sound velocity of ultrasonic waves, and h is the thickness of the CLP.

Meanwhile, referring to FIG. 6, the thickness measurement sensor 300 includes a signal transmission and reception coil 310, a converter body 320, a signal transmission and reception connector 330, a permanent magnet 340, and a converter cover 350. ), a converter fixing part 360 may be provided. The thickness measurement sensor 300 receives an AC current from the ultrasonic pulser/receiver 221 through a signal transmission and reception connector 330. An eddy current is generated in the conductor under the signal transmission and reception coil 310 by the AC current. Ultrasonic waves are generated in the thickness direction of the CLP by the eddy current and the permanent magnet 340.

The signal transmission and reception coil 310 proceeds within the CLP and receives a signal reflected from an interface and converts it into an electric signal. The converted electrical signal is transmitted to the ultrasonic pulser/receiver 221 through a signal transmission and reception connector 330. Through this, the ultrasonic pulser/receiver 221 receives a measurement signal from the thickness measurement sensor 222.

Meanwhile, only the thickness measurement sensor 222 may be disposed on the moving body 211, and the ultrasonic pulser/receiver 221 and the signal processing unit 223 may not be disposed. The ultrasonic pulser/receiver 221 and the signal processing unit 223 may be disposed outside the moving body 211 to be connected to the thickness measurement sensor 222 by wire or wirelessly. Through this, the present invention reduces the weight of the movable body 211 so that the movable body 211 does not fall off the CLP wall and can be easily moved. Meanwhile, for the same reason as the above-described remote control unit 212, it is preferable that the ultrasonic pulser/receiver 221 and the signal processing unit 223 are connected to the thickness measurement sensor 222 by wire.

Meanwhile, the present invention includes a gap control unit 230 for making the distance between the thickness measurement sensor 222 and the CLP wall surface constant. Since the thickness measurement sensor 222 and the CLP are in a non-contact state, the distance between the thickness measurement sensor 222 and the CLP always has a value greater than 0, and the thickness measurement sensor ( 222) and the CLP may vary.

When the distance between the thickness measurement sensor 222 and the CLP changes, signal measurement sensitivity may vary. For this reason, keeping the thickness measurement sensor 222 and the CLP interval constant is important for accurate thickness measurement.

The present invention may include a gap measurement unit 231 and a gap control unit 232 so that a gap between the thickness measurement sensor 222 and the CLP is kept constant even when the moving body 211 moves.

The gap measuring unit 231 is disposed on one surface of the moving body 211 as shown in FIG. 3 to continuously measure the distance between the moving body 211 and the CLP. According to the measurement result of the gap measurement unit 231, the gap control unit 232 disposed on the moving body 211 controls the gap between the thickness measurement sensor 222 and the CLP. Here, the gap control unit 232 may be a linear actuator, and the thickness measurement sensor 222 may be disposed on the linear actuator.

Meanwhile, the inspection apparatus 200 according to the present invention may further include a display unit 240. The display unit 240 may display the CLP thickness for each measurement location as a number or a two-dimensional image by combining the thickness measurement result according to Equation 1 and the measurement result of the location recognition unit 213. Through this, the user can check the thickness of each area of the CLP at a glance.

Finally, the present invention includes a power supply unit 250 for supplying power to the above-described components. The power supply unit is configured to apply power to each of the moving unit 210, the sensor unit 220, the gap control unit 230, and the display unit 240. The power supply unit 250 may be disposed on the moving body 211 in the form of a battery. However, in order to reduce the load of the moving body 211, it is preferable that the power supply unit 250 and the moving body 211 are connected by wire.

As described above, according to the present invention, since the thickness of the CLP can be measured in a non-contact method, reliable measurement is possible without being affected by the surface state of the CLP.

Further, according to the present invention, it does not require access to the contact medium and the inspector to measure the CLP thickness. For this reason, according to the present invention, it is possible to lower the inspection difficulty and shorten the inspection time.

Further, according to the present invention, since the CLP thickness can be continuously measured, it is possible to eliminate the measurement shadow area.

The effects of the present invention are not limited to the effects mentioned above, and other effects that are not mentioned will be clearly understood by those skilled in the art from the description of the claims.

Those of ordinary skill in the art to which the present invention pertains will be able to make various modifications and variations without departing from the essential characteristics of the present invention. Accordingly, the embodiments disclosed in the present invention are not intended to limit the technical idea of the present invention, but to explain the technical idea, and the scope of the technical idea of the present invention is not limited by these embodiments. The scope of protection of the present invention should be interpreted by the following claims, and all technical ideas within the scope equivalent thereto should be interpreted as being included in the scope of the present invention.

Claims (8)

In the mobile inspection device for measuring the thickness of the liner plate of a nuclear power plant containment,
A moving unit attached to a containment liner plate (CLP) of an inner surface of a nuclear power plant containment building and configured to be movable along the wall surface of the CLP;
A sensor unit for non-contact measuring the thickness of the CLP disposed on the mobile unit; And
And a gap control unit disposed on the mobile unit to constantly maintain a gap between the sensor unit and the CLP,
The gap control unit,
A gap measuring unit attached to the CLP and disposed on a moving body configured to be movable, and measuring a gap between the CLP and the moving body; And
A mobile inspection device for measuring the thickness of a liner plate of a nuclear power plant containment building, comprising a gap control unit disposed on the moving body and adjusting a gap between the CLP and the moving body. The method of claim 1,
The mobile unit,
A moving body attached to the CLP and made movable;
A remote control unit disposed to be spaced apart from the moving object to control the movement of the moving object; And
And a position recognition unit disposed on the moving body and configured to recognize the position of the moving body on the CLP. The method of claim 2,
The mobile inspection device for measuring the thickness of a liner plate of a nuclear power plant containment building, characterized in that the mobile body and the remote control unit are connected by wire. The method of claim 3,
The sensor unit,
A thickness measurement sensor that measures the thickness of the CLP in a non-contact manner;
An ultrasonic pulser and a receiver that transmits a reference signal to the thickness measurement sensor and receives a measurement signal from the thickness measurement sensor; And
A mobile inspection device for measuring the thickness of a liner plate of a nuclear power plant containment building, comprising a signal processing unit that analyzes the signal received from the ultrasonic pulser and the receiver. The method of claim 4,
The thickness measurement sensor is disposed on the moving body, and the ultrasonic pulser and receiver, and the signal processing unit are arranged spaced apart from the moving body. delete The method of claim 1,
The gap measurement unit measures a gap between the CLP and the mobile body in real time while the mobile body is moving,
The gap control unit controls the gap between the CLP and the moving body in real time so that the gap between the CLP and the thickness measurement sensor and the CLP is kept constant. Device. The method of claim 7,
The thickness measurement sensor,
Equipped with a coil and a permanent magnet,
After generating ultrasonic waves in the thickness direction of the CLP, the mobile inspection apparatus for measuring the thickness of the liner plate of a nuclear power plant containment building, characterized in that configured to receive a signal reflected from the CLP.

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