Transactions of the Korean Society of Pressure Vessels and Piping (한국압력기기공학회 논문집)

Korean Society of Pressure Vessels and Piping (한국압력기기공학회)
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Design and Test of ElectroMagnetic Acoustic Transducer applicable to Wall-Thinning Inspection of Containment Liner Plates

격납건물 라이너 플레이트 감육 검사를 위한 전자기 초음파 트랜스듀서의 설계 및 성능 평가

  • 한순우 (한국원자력연구원 안전재료기술개발부) ;
  • 조승현 (한국표준과학연구원 안전측정센터) ;
  • 강토 (한국원자력연구원 안전재료기술개발부) ;
  • 문성인 (한국원자력연구원 안전재료기술개발부)
  • Received : 2019.04.25
  • Accepted : 2019.06.10
  • Published : 2019.06.30
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Abstract

This work proposes a noncontact ultrasonic transducer for detecting wall-thinning of containment liner plates of nuclear power plants by measuring their thickness without physical contact. Because the containment liner plate is designed to prevent atmospheric leakage of radioactive substances under severe nuclear accident, its wall-thinning inspection is important for safety of nuclear power plants. Wall-thinning investigation of containment liner plates have been carried out by measuring their thickness with contact-type ultrasonic thickness gauge by inspectors and needs a lot of time and cost. As an alternative, an electromagnetic acoustic transducer measuring precisely thickness of containment liner plates without any physical contact or couplant was suggested in this research. A transducer generating and measuring shear ultrasonic waves in thickness direction was designed and wave field produced by the transducer was analyzed to verify the design. The working performance of the suggested transducer was tested with carbon steel plate specimens with various thicknesses. The test result shows that the proposed transducer can measure thickness of the specimens precisely without any couplant and implies that swift scanning of wall-thinning of containment liner plates will be possible with the proposed transducer.

Keywords

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Fig. 1 Schematic diagram of ultrasonic signal generation by an EMAT using Lorentz force mechanism

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Fig. 2 The proposed configuration of coil and magnet for measuring CLP thickness

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Fig. 3 Shear wave generation and propagation by a racetrack coil

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Fig. 4 Analysis of ultrasonic wave field at point P generated by a racetrack coil

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Fig. 5 The wave field analysis results of the proposed transducer according to coil turns

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Fig. 6 The racetrack coil for CLP thickness measurement transducer

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Fig. 7 Configuration of coils and a magnet of the proposed transducer

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Fig. 8 The exploded illustration of the proposed transducer

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Fig. 9 The developed CLP thickness noncontact measurement transducer

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Fig. 10 Schematic diagram of the experimental setup

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Fig. 11 Plate thickness measurement by using the proposed transducer

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Fig. 12 The signal generated at the steel plate of 300 × 300 × 6 mm by the transducer

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Fig. 13 Test specimens for the verification of working performance of the developed transducer

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Fig. 14 Signal generated by the proposed transducer at the test specimens in Fig. 13 (d : thickness of a test specimen)

Table 1 Thickness of the plate in Fig. 11 measured by the suggested transducer

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Table 2. Thickness of the specimens in Fig. 13 measured by the proposed transducer

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References

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