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Laboratorial technique for fabrication of outer diameter stress corrosion cracking on steam generator tubing
증기발생기 전열관 2차측 응력부식균열의 실험실적 모사 방법
Jae-Min Lee, Sung-Woo Kim, Seong-Sik Hwang, Hong-Pyo Kim, and Hong-Deok Kim
이재민, 김성우, 황성식, 김홍표, 김홍덕
Keywords: direct current potential drop method, eddy current test, non-through wall crack, steam generator tubing, stress corrosion cracking, through wall crack
Abstract: In this work, it is aimed to develop the fabrication method of axial stress corrosion cracking (SCC) defects having various sizes, on the outer diameter surface of the steam generator (SG) tubings. To control the length of the artificial SCC defect, the specific area of the SG tubing samples was exposed to an acidic solution after a sensitization heat treatment. During the exposure to an acidic solution, a direct current potential drop (DCPD) method was adopted to monitor the crack depth. The size of the SCC defect was first evaluated by an eddy current test (ECT), and then confirmed by a destructive examination. From the comparison, it was found that the actual crack length was well controlled to be similar to the length of the surface exposed to an acidic solution (5, 10, 20 or 30 mm in this work) with small standard deviation. From in-situ monitoring of the crack depth using the DCPD method, it was possible to distinguish a non-through wall crack from a through wall crack, even though the depth of the non-through wall crack was not able to be precisely controlled. The fabrication method established in this work was useful to simulate the SCC defect having similar size and ECT signals as compared to the field cracks in the SG tubings of the operating Korean PWRs.