JP4427409B2 - Double pipe gap amount measuring device and double pipe gap amount measuring method - Google Patents

Description

  The present invention relates to a technique for measuring a gap between an inner tube and an outer tube of a double pipe.

  In a liquid metal cooled fast breeder reactor plant, liquid sodium is used as a coolant. In the steam generator, heat is exchanged between liquid sodium and water to generate steam from the water.

  Liquid sodium and water react violently when in contact. Therefore, the steam generator is required to have high reliability so that liquid sodium and water do not react. As a contrivance for this, use of a double heat transfer tube having a double wall at the boundary between water and sodium has been studied.

  In a steam generator in which a large number of heat transfer tubes are arranged in a main body cylinder through which liquid metal circulates and water supplied to the heat transfer tubes is heated by heat exchange with the liquid metal to generate steam, the heat transfer tubes are The double heat transfer tube is composed of an outer tube and an inner tube, and the double heat transfer tube is divided into (M × N) groups (M> 1, N> 1), while the steam side of the double heat transfer tube and water supply The M main steam pipe plates and the N main water supply pipe plates that respectively join the end portions to the side are provided, and the main steam pipe plate and the main water supply pipe plate are filled with an inert gas. A gas plenum communicating with the gap between the inner and outer pipes of the heat transfer pipe is formed, and one side of the (M × N) pair of gaps of the double heat transfer pipe is communicated with the gas plenum of the M-th main steam pipe plate. The other side of the gap of the (M × N) set of heat transfer tubes is connected to the gas plenum of the Nth main water supply tube plate. Steam generator is known that (see Patent Document 1).

Japanese Patent No. 2950652

  When the gap between the inner tube and the outer tube of the double heat transfer tube is large, the heat transfer performance between the water inside the inner tube and the liquid sodium outside the outer tube decreases. Furthermore, if water leaks from the inner pipe, it is preferable that the amount of water leaking from safety is small. For these reasons, it is desirable that the gap between the inner tube and the outer tube is small. Preferably, it is about several microns.

  A technique for measuring the size of the gap between the inner tube and the outer tube is desired. In particular, the fast breeder reactor steam generator is expected to be used for a long period of about 60 years, so the size of the gap may change over time, and the technology for measuring the gap between the inner and outer pipes is important. It is.

  An object of the present invention is to provide a double pipe gap amount measuring device and a double pipe gap quantity measuring method for measuring a gap between double pipes.

  In the following, means for solving the problem will be described using the numbers used in [Best Mode for Carrying Out the Invention] in parentheses. These numbers are added to clarify the correspondence between the description of [Claims] and [Best Mode for Carrying Out the Invention]. However, these numbers should not be used to interpret the technical scope of the invention described in [Claims].

According to the double pipe gap measuring method of the present invention, ultrasonic waves emitted vertically from the inside of the inner pipe (20) housed in the outer pipe (24) of the double pipe to the wall surface of the inner pipe (20) are inner. A step of measuring the intensity (H ₁ ) of the first reflected wave (30) reflected by the walls before and after the gap (22) between the tube (20) and the outer tube (24); Measuring the intensity (H ₂ ) of the second reflected wave (32) reflected by the outer wall (26), the intensity (H ₁ ) of the first reflected wave (30), and the intensity of the second reflected wave (32) And a calculation step of calculating the size of the gap (22) between the inner pipe (20) and the outer pipe (24) based on (H ₂ ).

Double tube gap amount measuring method according to the invention, the size of the intensity of the intensity of the first reflected wave (30) _{(H 1)} and the second reflected wave (32) _{(H 2)} and the ratio and the clearance (22) The step of calculating the size of the gap (22) from the ratio calculated in the calculating step by referring to the database (50) relating

  In the double pipe gap measuring method according to the present invention, an ultrasonic wave having a predetermined frequency is vertically applied from the inside of the inner pipe (20) accommodated in the outer pipe (24) of the double pipe to the wall surface of the inner pipe (20). A step of firing, a step of measuring the reflected wave (32) returned by the reflection of the ultrasonic wave on the outer wall (26) of the outer tube (24), the reflected wave (32), and an ultrasonic wave of a predetermined frequency Obtaining information on the size of the gap (22) by comparing with a database indicating how wide the gap (22) propagates.

The double pipe clearance measuring apparatus according to the present invention is configured to receive ultrasonic waves emitted vertically from the inside of the inner pipe (20) accommodated in the outer pipe (24) of the double pipe to the inner wall of the inner pipe (20). The intensity (H ₁ ) of the first reflected wave (30) reflected and returned by the wall surfaces before and after the gap (22) between the tube (20) and the outer tube (24) is measured, and further, the ultrasonic wave is An ultrasonic detector that measures the intensity (H ₂ ) of the second reflected wave (32) that has been reflected and returned by the outer wall (26) of the tube (24), and the intensity (H of the first reflected wave (30)) ₁ ) and a computer (18) for calculating the size of the gap (22) between the inner tube (20) and the outer tube (24) based on the intensity (H ₂ ) of the second reflected wave (32). ing.

Double tube gap amount measuring apparatus according to the present invention, the ratio of the intensity of the intensity of the first reflected wave (30) _{(H 1)} and the second reflected wave (32) _{(H 2),} gaps (22) size A database (50) is provided. Calculator (18), the intensity of the first reflected wave (30) and _{(H 1)} to calculate the ratio of the intensity _{(H 2)} of the second reflected wave (32), in the database (50) to the calculated ratio The size of the corresponding gap (22) is calculated.

  The double pipe gap amount measuring device according to the present invention transmits ultrasonic waves having a predetermined frequency from the inside of the inner pipe (20) accommodated in the outer pipe (24) of the double pipe to the inner wall of the inner pipe (20). The ultrasonic detection unit that measures the reflected wave that has been launched and the ultrasonic waves reflected back from the outer wall of the outer tube (24) and the gap (22) between the inner tube (20) and the outer tube (24) The ultrasonic detector detects a size and a database that stores ultrasonic waves having a predetermined frequency in association with the intensity reflected by the outer wall of the outer tube (24) through the gap (22) and the database. And a computer (18) for calculating information on the size of the gap (22) from the reflected wave.

  ADVANTAGE OF THE INVENTION According to this invention, the double pipe gap amount measuring apparatus and the double pipe gap amount measuring method which measure the gap of a double pipe are provided.

  The best mode for carrying out the present invention will be described below in detail with reference to the drawings.

  Referring to FIG. 1, there is shown a configuration of a double pipe gap amount measuring device according to the present invention. The double tube gap amount measuring device 1 is a device in which an ultrasonic flaw detector and a computer are connected. Specifically, the double tube gap amount measuring device 1 includes a transducer 4, a probe 6, an oscillator 8, a receiving unit 10, a time axis unit 12, a display unit 14, an A / D conversion unit 16, and a computer 18. ing.

  The oscillator 8 generates an electric pulse and transmits it to the probe 6. The probe 6 receives a pulse, and the received pulse is converted into an ultrasonic wave having a specific frequency by the vibrator 4. The ultrasonic wave is transmitted to the subject 2. The probe 6 also changes the sound pressure of the echo received by the transducer 4 from the subject 2 to the voltage of the electric signal and transmits it. The receiving unit 10 amplifies the voltage of the electrical signal received from the probe 6. The time axis unit 12 generates and transmits a signal for indicating time. Signals from the time axis unit and the receiving unit are sent to the display unit 14. The display unit 14 includes a cathode ray tube or the like, and displays a signal waveform having the horizontal axis as the time received from the time axis unit 12 and the vertical axis as the voltage received from the receiving unit. The A / D conversion unit 16 performs A / D conversion on the signal received from the time axis unit 12 and the signal received from the reception unit 10 and transmits the result to the computer 18.

  Referring to FIG. 2, the configuration of the computer 18 is shown. The computer 18 includes a communication unit 34 that receives a signal from the A / D conversion unit 16, an input unit 36, an output unit 38 that includes a display, a printer, and the like, a CPU 40, and a storage unit 42.

  Referring to FIG. 3, data stored in the storage unit 42 is shown. The storage unit 42 stores a wave height extraction program 44, a wave height ratio calculation program 46, a gap calculation program 48, and a database 50. The database 50 stores the wave height ratio 52 and the gap size 54 in association with each other.

  Referring to FIG. 4, there is shown a heat transfer tube to which the double pipe gap amount measuring device 1 and the double pipe gap amount measuring method according to the present invention is applied. The heat transfer tube 56 is, for example, a heat transfer tube of a steam generator 57 of a nuclear power plant. The heat transfer tube 56 is connected to the inlet 60 and the outlet 58. The inlet 58 and the outlet 60 are provided with a detachable lid, and the vibrator 4 and the probe 6 can be introduced into the heat transfer tube 56 by removing the lid.

  Referring to FIG. 5, a state in which a part of the heat transfer tube 56 is cut out and enlarged is shown. The heat transfer tube 56 is a double tube of the inner tube 20 and the outer tube 24. There is a gap 22 between the inner tube 20 and the outer tube 24. Although the gap 22 is exaggerated in the drawing, the gap 22 is actually very small, for example, several microns.

  Such a double pipe gap amount measuring device 1 operates as follows.

In the double pipe as shown in FIG. 5, the double pipe gap amount measuring apparatus 1 sends ultrasonic waves perpendicularly to the wall surface from the inner wall of the double pipe toward the outside. When the double pipe gap amount measuring device 1 is used for a double pipe, a display as shown in FIG. First, the display unit 14 displays the transmission pulse 28 at substantially the origin of the time axis (horizontal axis). The display unit 14 further displays a reflected wave 30 (height H ₁ ) reflected by the outer wall of the inner tube 20 and a reflected wave 32 (height H ₂ ) reflected by the outer wall 26 of the outer tube 24.

The height H ₁ of the reflected wave 30 reflected by the outer wall of the inner tube 20 includes the height of the reflected wave reflected by the inner wall of the outer tube.

When the gap 22 is large, since the ultrasonic wave does not propagate from the inner tube 20 to the outer tube 24, the reflected wave 32 from the outer wall 26 of the outer tube 24 is not detected and is not displayed on the display unit 14. When the gap 22 is very small size of about several microns, as the gap is small ultrasound is more strongly propagated to the outer tube 26, the height H ₂ of the reflected waves 32 from the outer wall 26 increases. That is, a functional relationship is established in which the ratio of H ₂ to H ₁ increases as the size of the gap 22 decreases.

The ratio of the height of H _{2 to} H ₁ and the size of the gap 22 can be examined by some method such as an experiment using a sample whose gap size is known, and the wave height ratio 52 and the gap size are stored in the database 50 in advance. Are stored in association with each other.

  Information output to the display unit 14 is converted into digital data by the A / D conversion unit and input to the computer 18. Hereinafter, the process that the CPU 40 reads out a program and performs according to the procedure described in the program is described as an operation performed by the program.

The wave height extraction program 44 extracts a peak wave height H ₁ near the gap 22 and a peak wave height H ₂ near the outer wall 26 along the time axis. The wave height ratio calculation program 46 calculates H ₂ / H ₁ . The gap calculation program 48 searches the database 50, calculates the gap size 54 corresponding to the calculated H ₂ / H ₁ , and outputs it to the output unit 38.

  The above operations performed by the computer 18 may be performed manually by a human by referring to the display on the display unit 14 with reference to a paper medium or a database realized by the computer.

  By performing the above operation for each predetermined distance in the length direction of the double pipe, it is possible to know the size of the gap of the double pipe over the entire double pipe. it can.

  As another method for examining the size of the gap between the double tubes, there is a method using the relationship between the frequency of ultrasonic waves used by the ultrasonic flaw detector and the size of the gap between the double tubes. The ultrasonic wave having a predetermined frequency is less likely to pass through the gap as the gap between the double tubes is larger. Therefore, the echo from the outer wall 26 of the outer tube is reduced. If the relationship between the size of the echo from the outer wall of the outer tube and the size of the gap between the double tubes has been created in advance in a database, the size of the gap between the double tubes can be calculated from the size of the echo from the outer wall of the outer tube. I can know. Preferably, if an ultrasonic flaw detector capable of using a plurality of ultrasonic frequency bands is used, a double tube of various sizes can be obtained by switching the ultrasonic frequency band according to the size of the gap. This method can be used for the gaps.

  More preferably, an apparatus capable of generating an ultrasonic wave having a variable frequency is used. How much gap is transmitted is determined by the frequency of the ultrasonic wave. If the relationship is made into a database, it is possible to examine the size of the gap by measuring the size of the echo reflected from the outer wall 26 of the outer tube while changing the frequency.

FIG. 1 shows a configuration of a double pipe gap amount measuring device. FIG. 2 shows the configuration of the computer. FIG. 3 shows the structure of data stored in the storage unit. FIG. 4 shows the piping of the steam generator. FIG. 5 shows a double pipe. FIG. 6 shows the inspection result of the double pipe by the ultrasonic flaw detection test.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Double tube clearance amount measuring device 2 ... Subject 4 ... Vibrator 6 ... Probe 18 ... Computer 20 ... Inner tube 22 ... Gap 24 ... Outer tube 26 ... Outer wall 28 ... Transmission pulse 30 ... Reflected wave 32 ... Reflection Wave 42 ... Memory 50 ... Database 56 ... Heat transfer tube 58 ... Outlet 60 ... Inlet

Claims (6)

A first reflected wave in which ultrasonic waves emitted perpendicularly to the wall surface of the inner tube from the inside of the inner tube housed in the outer tube of the double tube are reflected by the front and rear walls of the gap between the inner tube and the outer tube. Measuring the intensity of
Measuring the intensity of the second reflected wave reflected from the outer wall of the outer tube by the ultrasonic wave;
Calculating a ratio between the intensity of the first reflected wave and the intensity of the second reflected wave;
A method for measuring a gap between the double pipes, comprising: calculating a size of the gap from the ratio by referring to a database that relates the ratio and the size of the gap. Emitting ultrasonic waves of a predetermined frequency vertically from the inside of the inner tube housed in the outer tube of the double tube to the wall surface of the inner tube;
Measuring the reflected wave returned from the ultrasonic wave reflected by the outer wall of the outer tube;
Obtaining information on the size of the gap from the measured magnitude of the reflected wave by referring to a database relating the magnitude of the reflected wave and the size of the gap between the inner tube and the outer tube ; A method for measuring a gap between double pipes. Emitting ultrasonic waves while changing the frequency vertically from the inside of the inner tube housed in the outer tube of the double tube to the wall surface of the inner tube;
Measuring the reflected wave returned from the ultrasonic wave reflected by the outer wall of the outer tube;
With reference to a database showing the relationship between the ultrasonic frequency and how much gap the ultrasonic wave penetrates, the inner tube and the ultrasonic wave are calculated from the ultrasonic frequency and the magnitude of the measured reflected wave. And a step of obtaining information on the size of the gap between the outer pipe and the outer pipe . Ultrasonic waves emitted perpendicularly to the inner wall of the inner tube from the inside of the inner tube housed in the outer tube of the double tube are reflected and returned by the wall surfaces before and after the gap between the inner tube and the outer tube. An ultrasonic detector that measures the intensity of the first reflected wave, and further measures the intensity of the second reflected wave that is reflected back by the outer wall of the outer tube,
A database relating the ratio of the intensity of the first reflected wave and the intensity of the second reflected wave and the size of the gap;
A computer that calculates a ratio between the intensity of the first reflected wave and the intensity of the second reflected wave detected by the ultrasonic detector, and calculates the size of the gap corresponding to the calculated ratio in the database. A double pipe clearance measuring device. An ultrasonic wave of a predetermined frequency was emitted from the inside of the inner pipe accommodated in the outer pipe of the double pipe to the inner wall of the inner pipe, and the ultrasonic wave was reflected and returned to the outer wall of the outer pipe. An ultrasonic detector for measuring the reflected wave;
A database that stores the size of the gap between the inner tube and the outer tube and the intensity at which the ultrasonic wave of the predetermined frequency passes through the gap and is reflected by the outer wall of the outer tube;
A double pipe gap amount measuring device comprising: a computer that refers to the database and calculates information related to the size of the gap from the reflected wave detected by the ultrasonic detector. Ultrasonic waves are emitted from the inside of the inner pipe housed in the outer pipe of the double pipe while changing the frequency perpendicular to the inner wall of the inner pipe, and the ultrasonic waves are reflected back to the outer wall of the outer pipe. An ultrasonic detector for measuring reflected waves,
A database for storing the size of the gap between the inner tube and the outer tube, the frequency of the ultrasonic wave, and the intensity at which the ultrasonic wave of the frequency passes through the gap and is reflected by the outer wall of the outer tube;
A double pipe gap amount measuring device comprising: a computer that refers to the database and calculates information related to the size of the gap from the reflected wave detected by the ultrasonic detector.

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