레이저 계측법을 이용한 압력용기 결함두께 측정 신뢰성 평가

Abstract

ABSTRACT

Reliability Assessment on Thickness measurement of Pressure Vessel Using Laser Diagnostics

By Park, Chan Sic Advisor : Prof. Kim, Kyeong-Suk, Ph. D. Dept. Advanced Parts & Materials Engineering. Graduate School of Chosun University.

In the industrial site, much used industrial facility and subsidiary materials has high possibility of the deformity. Due to destruction of them, there can be the enormous loss. Therefore, the non-destructive test technique detecting the deformity quickly and accurately manages the role of being important in the whole industry. In addition, the industry technology development requires smaller, more various and reliable goods. In order to be satisfied this, non-destructive inspection changes from the contact type testing technology into the noncontact inspection technology. Particularly, much used supersonic flaw detecting test and radiant-ray test develops are being developed for the inside defect test. However, the supersonic flaw detecting test has time consumption for test and the application limit about complicated structure and anisotropy material objects according to the Point by point scanning inspection plan. When measuring the deformity, the supersonic flaw detecting test has the limit due to the restrictive cause of the risk about the radiation exposure and radiological scan direction as shown in Nuclear Electrical Power Plant of Fukushima, Japan. In this aspect, the non-destructive test technique including the Electronic Speckle Pattern Interferometry, Shearography, Thermography, and etc. is the tendency that the application is gradually enhanced in local and foreign industrial site. The laser application technology based on interferometer, laser based ultrasonic testing, Holography, speckle correlation interferometry etc. It is applied in the field including the vibration or deformation analysis, vibration analysis, non-destructive inspection, and etc. in the advantage that at the same time it measures the surface displacement of the wide area with the high resolution. In addition, the speckle correlative method for the non-destructive inspection is being developed into ESPI and Shearography and it is applied in the field including the deformation analysis of all sorts of structures, noise and vibration analysis, non-destructive inspection, and etc. With computer science and image processing technology, film-based speckle correlation interferometry evolves into ESPI, which substitute the film-based by the digitalized with CCD camera. This technology was developed in the U.S. and United Kingdom at the early 1970's at the same time and presently this application range widens to the Field of engineering. electronic speckle pattern interference technique was developed into the Phase shifting method developed by K. Creath, which can automatically extract a phase from interference pattern and demodulate the surface displacement of a target. Therefore, in this research, the thickness of the pressure vessel defect which comes into question in many industrial fields including the Nuclear Power Plant and field of the plant facility, and etc. by using the electronics speckle pattern interferometry, that is one among the laser measuring technology, is detected and the reliability is evaluated so that the theoretical access method tries to be shown and this tries to be verified through the experiment. In this research, the basic idea for measuring the defective thickness of the pressure vessel is to analyze the quantity detection mechanism of the pressure vessel deformity and to estimates the thickness of the pressure vessel internal defect through the test verification quantitatively. In this research, by using the inspection technique to be proposed, the size of the internal defect of the pressure vessel, shape, and location can be inspected with the high resolution and the concept of the quantitative nondestructive evaluation can be satisfied based on product reliability evaluation. It is expected to contribute to the base establishment promoting the Nuclear Power Plant, safety of all sorts of structures, soundness, and water retention as the fundamental research that theory including the pressure vessel deformity thickness prediction and dry well assessment technology development, and etc. and experiment are combined based on this.