JP2005283413A - Method and device for monitoring cracking of plant member - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and device for monitoring cracking of a plant member, capable of monitoring cracking such as stress corrosion cracking in a member such as a pipe of a plant with a simple structure without setting a reference electrode, a lead wire or the like in water on the inside of the pipe, or providing a pressure resistant flange part for taking the lead out of the pipe. <P>SOLUTION: In this method, a piezoelectric film 2 is provided on the surface of the plant member 1, and a voltage change caused in the film 2 is measured to monitor the generation or development of cracking in the plant member 1 during operation. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a crack in a plant member that monitors cracks such as stress corrosion cracking (SCC) in a member (such as a plant member for convenience) such as piping and containers constituting a plant such as a nuclear power plant and a thermal power plant online. The present invention relates to a monitoring method and apparatus.

  Austenitic stainless steel with excellent corrosion resistance is mainly used as a material for parts exposed to high-temperature water during operation in a nuclear power plant. It has been reported that there is a possibility that stress corrosion cracking may occur when residual stress in the tensile direction exists in the welded part of the plant member and a work hardened layer exists on the surface of the plant member in contact with high-temperature water. Nuclear power plants are periodically shut down once a year, and the presence of stress corrosion cracks is visually inspected for welds of recirculation pipes and furnace structures that come into contact with high-temperature water to check the soundness of the plant. I have confirmed.

  If stress corrosion cracking occurs and it is determined that repair measures are necessary, it is important to improve the operating rate by taking repair measures immediately and restarting the plant. For this reason, there is a great need for a technique for monitoring the occurrence of stress corrosion cracking during plant operation as well as during periodic inspection of welds and the like. If the occurrence of stress corrosion cracking is detected during operation, it will be examined whether repair measures are necessary, and if it is determined that repair measures are necessary, by preparing repair work for the relevant part by the next periodic inspection, The part can be repaired immediately.

A method of constantly detecting stress corrosion cracking in water piping of a plant has already been proposed. Like the corrosion detection system described in Patent Document 1 below, a plurality of reference electrodes are inserted into a corrosion monitoring unit of a pipe, and the monitoring unit There is a method of detecting the occurrence of corrosion by monitoring the potential difference between the electrode and the reference electrode. However, in this method, it is necessary to install a reference electrode and a lead wire in the water inside the pipe, and to provide a pressure-resistant flange portion for taking out the lead wire to the outside of the pipe.
JP-A-4-83153

  The present invention provides a simple structure for a member such as a pipe of a plant without installing a reference electrode, a lead wire or the like in the water inside the pipe or providing a pressure-resistant flange portion for taking out the lead wire to the outside of the pipe. It is an object of the present invention to provide a crack monitoring method and apparatus for plant members that can monitor on-line the occurrence or propagation of cracks such as stress corrosion cracking.

  In order to achieve the above object, the invention of claim 1 is provided with a piezoelectric film on the surface of a plant member, and a voltage change occurring in the piezoelectric film is measured to generate cracks in the plant member during operation or A method of monitoring progress.

  The invention of claim 2 is a method of transmitting a voltage change of the piezoelectric film to a receiver installed outside via a telemetry unit including a power source and a transmitter during plant operation.

  According to a third aspect of the present invention, the voltage change of the piezoelectric film is taken into a storage unit including a power source, a clock, and a memory, and information on the voltage change stored in the storage unit is extracted during a plant stop period to operate the plant. It is a method for evaluating the occurrence or propagation of cracks in the inside.

  According to a fourth aspect of the present invention, a voltage change of the piezoelectric film is taken into a capacitor, information on the voltage change stored in the capacitor is extracted during a plant shutdown period, and cracks are generated or propagated during plant operation. It is a method to evaluate.

  According to a fifth aspect of the present invention, there is provided a piezoelectric film provided on a surface of a plant member, an electrode provided on each of the plant member and the voltage film, a power source and a transmitter, and connected to the electrode. A telemetry unit provided on or near the surface of the member and a receiver provided outside are provided.

  The invention of claim 6 includes a piezoelectric film provided on the surface of the plant member, electrodes provided on the plant member and the voltage film, a power source, a clock, and a memory, and is connected to the electrode. It is set as the structure provided with the memory | storage part provided in the surface or the vicinity of the said plant member.

  The invention of claim 7 includes a piezoelectric film provided on a surface of a plant member, electrodes provided on the plant member and the voltage film, a down transformer, a rectifier, and a capacitor, and is connected to the electrode. And a power storage circuit provided on or near the surface of the plant member.

  The invention according to claim 8 is that the piezoelectric film is made of a material in which a carbon fiber composite reinforced plastic powder is mixed in an epoxy resin, a material in which a fine powder of zirconate titanate is mixed in an epoxy resin, or a piezoelectric polymer. The composition is made of material.

  According to the present invention, without installing a reference electrode, a lead wire, or the like in the water inside the pipe, or providing a pressure-resistant flange portion for taking out the lead wire to the outside of the pipe, a simple structure such as a pipe of a plant can be used. It is possible to provide a plant member crack monitoring method and apparatus capable of monitoring on-line the occurrence or propagation of a crack such as stress corrosion cracking in a member.

Hereinafter, first and second embodiments of the present invention will be described with reference to the drawings.
(First embodiment)
FIG. 1 shows a plant member crack monitoring method and apparatus according to the present embodiment. The monitoring device includes a piezoelectric film 2, an electrode 3, a storage unit 4, and a telemetry unit 5 provided on the plant member 1, and a receiver 6 provided at a location away from the plant member 1 or at a safe location.

  A piezoelectric coating 2 is formed by applying a piezoelectric paint to the outer surface of a welded portion, a bent portion, or the like that may cause stress corrosion cracking of the plant member 1 such as piping, and occurs in response to the strain of the plant member 1. The potential difference between the plant member 1 and the piezoelectric film 2 is recorded in the storage unit 4 via the electrode 3. Alternatively, the potential difference information is taken into the telemetry unit 5.

  The storage unit 4 includes a clock 7, a battery 8, and a memory 9, and stores potential difference information from the piezoelectric film 2 that changes over time on the memory 9, and stores the memory information in the data recording device during periodic inspection. To evaluate the occurrence of stress corrosion cracking during operation. Thus, for members that do not need to be monitored in real time during plant operation, it is possible to obtain information regarding the occurrence or propagation of cracks while the plant is stopped.

  The telemetry unit 5 includes a battery 15 and a transmitter 10 and wirelessly transmits potential difference information from the piezoelectric film 2 to the receiver 6 during operation. By using the telemetry unit 5, the occurrence or development of stress corrosion cracking can be monitored in real time during plant operation.

  As the piezoelectric film 2, a material in which a carbon fiber composite reinforced plastic powder is mixed in an epoxy resin or a material in which a fine powder of zirconate titanate (PZT) is mixed in an epoxy resin is used. Alternatively, a piezoelectric polymer material such as vinylidene fluoride (PVDF) may be used.

  By adopting the above-described configuration, the piezoelectric film 2 is distorted in accordance with the strain on the outer surface of the pipe or the like due to the occurrence or development of stress corrosion cracks on the inner surface of the plant member 1 such as the pipe, The potential difference generated in the conductive film 2 can be detected by the electrode 3 and monitored via the storage unit 4 or the telemetry unit 5. Therefore, it is possible to prevent the occurrence and development of cracks in plant members such as pipes without installing reference electrodes, lead wires, etc. in the water inside the pipes or providing pressure-resistant flanges that take out the lead wires to the outside of the pipes. Can be detected in.

(Second Embodiment)
FIG. 2 is a diagram showing a second embodiment of the present invention.
In the present embodiment, a power storage circuit 11 is provided in the vicinity of the piezoelectric film 2 instead of the storage unit 4 and the telemetry unit 5 in FIG. 1, and the piezoelectric film 2 is interposed via the down transformer 12 and the diode 13 in the power storage circuit 11. Is accumulated in the capacitor 14 as electric charges. Since this power storage circuit 11 does not require an external power source or a battery, the apparatus is simple, inexpensive and highly reliable. By periodically measuring the charge information stored in the capacitor 14 during plant operation or periodic inspection, it is possible to detect the occurrence or development of stress corrosion cracking.

  Therefore, according to the present embodiment, it is possible to monitor stress corrosion cracking that may occur in members in a nuclear power plant or the like on-line, which is effective for extending the life of the plant and for maintenance measures. Can be improved.

The crack monitoring method and apparatus of the plant member of the 1st Embodiment of this invention are shown, (a) is a perspective view which shows the attachment condition of the apparatus to a plant member, (b) is a block diagram which shows the structure of an apparatus. . The crack monitoring method and apparatus of the plant member of the 2nd Embodiment of this invention are shown, (a) is a perspective view which shows the attachment condition of the apparatus to a plant member, (b) is a block diagram which shows the structure of an apparatus. .

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Plant member, 2 ... Piezoelectric membrane, 3 ... Electrode, 4 ... Memory | storage part, 5 ... Telemetry part, 6 ... Receiver, 7 ... Clock, 8 ... Battery, 9 ... Memory, 10 ... Transmitter, 11 ... Power storage circuit, 12 ... down transformer, 13 ... diode, 14 ... capacitor, 15 ... battery.

Claims (8)

  A crack monitoring of a plant member characterized in that a piezoelectric film is provided on the surface of the plant member, and a change in voltage generated in the piezoelectric film is measured to monitor the occurrence or progress of a crack in the plant member during operation. Method.   2. The plant member crack monitoring method according to claim 1, wherein the voltage change of the piezoelectric film is transmitted to a receiver installed outside through a telemetry unit including a power source and a transmitter during plant operation.   The voltage change of the piezoelectric film is taken into a storage unit consisting of a power source, a clock and a memory, and information on the voltage change stored in the storage unit is extracted during a plant stop period to generate a crack during plant operation or The crack monitoring method for a plant member according to claim 1, wherein the progress is evaluated.   The voltage change of the piezoelectric film is taken into a capacitor, and information on the voltage change stored in the capacitor is extracted during a plant stop period to evaluate the occurrence or progress of a crack during plant operation. The crack monitoring method of the plant member of Claim 1.   A piezoelectric film provided on the surface of the plant member, an electrode provided on each of the plant member and the voltage film, a power source and a transmitter, connected to the electrode and provided on or near the plant member A crack monitoring device for a plant member, comprising: a telemetry section provided, and a receiver provided outside.   A piezoelectric film provided on the surface of the plant member, an electrode provided on each of the plant member and the voltage-sensitive film, a power source, a clock, and a memory, and connected to the electrode to be near or on the surface of the plant member A crack monitoring device for plant members, comprising: a storage unit provided in the plant.   A piezoelectric film provided on the surface of the plant member; electrodes provided on the plant member and the voltage film; respectively; a down transformer, a rectifier, and a capacitor; A plant member crack monitoring apparatus comprising a storage circuit provided in the vicinity. The piezoelectric film is made of a material obtained by mixing a carbon fiber composite reinforced plastic powder in an epoxy resin, a material obtained by mixing a zirconate titanate powder in an epoxy resin, or a piezoelectric polymer material. A plant member crack monitoring apparatus according to any one of claims 5 to 7.

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