스페클 전단간섭법을 이용한 마이크로급 변형 분석을 기초한 원전배관 감육 결함부 크기별 정량평가

Abstract

ABSTRACT

Evaluation of Thinning Defect Size in Nuclear Piping by Micro-scale Deformation Test Based on Shear Capacity by Using Shearography Interferometry By Sun-do Jang Advisor : Prof. Kyeong-Suk Kim, Ph.D. Dept. of Mechanical System Engineering Graduate School, Chosun University

Corrosion and cracks can occur in the piping part of high temperature and high pressure environment at the fragile part of the nuclear power plant when this defect grows. Particulary, there is a possibility of radiation leakge accident when leakage defects in the piping section of the primary system occur, so accurate inspection of corrosion and cracking is required. Flow-Acceleated Corrosion(FAC) inside the piping section often generates thinning phenomenon due to corrosion of piping section, and FAC is greatly affected by piping section environmental factors suxh as temperature and pressure. Therefore, there is a need for a non-distructive early diagnosis technique to inspect the corrosion into piping using the nuclear power plant. The shearing interferometry method, which is a non-contact method using a lasser that is handled in this research, can acquire distortion information directly with a digital-based technology that can properly construct an optical interferometer and obtain information of deformation. While shearing interferometers have interference signal processing algorithms such as ESPI, there is an advantage that the first derivative value of out-of -displacement can be directly measured due to the difference in configuration of the interferometer. These advantages can be analysed for distortion and vibration analysis by measuring changes in out-of-plane displacement while being insensitive to oscillation disturbance in the external environment and can be applied to non-destructive inspections such as quantification of defects. In this paper, shearography, which is a non-contact method using a laser that is handled. One diffuse light is applied on target, and diffused reflection from speckle is split into two lights. One is introduced to mirror 1 and reflected to image plane. The other is reflected from mirror 2, and formed on image plane through light splitter. Meanwhile, according to arbitrary angle in mirror 2, image from mirror 2 will be horizontally sheared from the one from mirror 1, and is formed at image plane of CCD. Mirror 2 is called as shearing mirror, and inclined angle is denoted as shearing amount, δx. Because of the influence of shearing direction and amount of shear, interference stripe is formed. We used a commercially available device (Q - 800 HR) to measure deformation due to micro-deformation of plate specimen, and constructed a system for basic experiment of plate specimen. the shear angle was the same, and the shear amount and deformation amount were given for each size. the larger the shear amount and deformation in the basic experiment using the plate specimen test evaluation, the phase map image is clearly clear. piping test pieces with different widths of defects were created by duplicating the piping used for the secondary piping system. in order to quantitatively confirm the displacement of the defective part, it was confirmed that the displacement corresponding to the pressure when provided in the form of a graph was using a line profile after the image filtering, and there was a little difference.