• Title/Summary/Keyword: Corrosion detection

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Evaluation of Piping Failure Probability of Reactor Coolant System in Kori Unit 1 Considering Stress Corrosion Cracking (응력부식균열을 고려한 고리 1호기 원자로냉각재계통의 배관 파손확률 평가)

  • Park, Jeong Soon;Choi, Young Hwan;Park, Jae Hak
    • Transactions of the Korean Society of Pressure Vessels and Piping
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    • v.6 no.1
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    • pp.43-49
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    • 2010
  • The piping failure probability of the reactor coolant system in Kori unit 1 was evaluated considering stress corrosion cracking. The P-PIE program (Probabilistic Piping Integrity Evaluation Program) developed in this study was used in the analysis. The effect of some variables such as oxygen concentration during start up and steady state operation, and operating temperature, which are related with stress corrosion cracking, on the piping failure probabilities was investigated. The effects of leak detection capability, the size of big leak, piping loops, and reactor types on the piping failure probability were also investigated. The results show that (1) LOCA (loss of coolant accident) probability of Kori unit 1 is extremely low, (2) leak probability is sensitive to oxygen concentration during steady state operation and operating temperature, while not sensitive to the oxygen concentration during start up, and (3) the piping thickness and operating temperature play important roles in the leak probabilities of the cold leg in 4 reactor types having same inner diameter.

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Laser based impedance measurement for pipe corrosion and bolt-loosening detection

  • Yang, Jinyeol;Liu, Peipei;Yang, Suyoung;Lee, Hyeonseok;Sohn, Hoon
    • Smart Structures and Systems
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    • v.15 no.1
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    • pp.41-55
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    • 2015
  • This study proposes a laser based impedance measurement system and impedance based pipe corrosion and bolt-loosening monitoring techniques under temperature variations. For impedance measurement, the laser based impedance measurement system is optimized and adopted in this paper. First, a modulated laser beam is radiated to a photodiode, converting the laser beam into an electric signal. Then, the electric signal is applied to a MFC transducer attached on a target structure for ultrasonic excitation. The corresponding impedance signals are measured, re-converted into a laser beam, and radiated back to the other photodiode located in a data interrogator. The transmitted impedance signals are treated with an outlier analysis using generalized extreme value (GEV) statistics to reliably signal off structural damage. Validation of the proposed technique is carried out to detect corrosion and bolt-loosening in lab-scale carbon steel elbow pipes under varying temperatures. It has been demonstrated that the proposed technique has a potential to be used for structural health monitoring (SHM) of pipe structures.

A review of chloride induced stress corrosion cracking characterization in austenitic stainless steels using acoustic emission technique

  • Suresh Nuthalapati;K.E. Kee;Srinivasa Rao Pedapati;Khairulazhar Jumbri
    • Nuclear Engineering and Technology
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    • v.56 no.2
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    • pp.688-706
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    • 2024
  • Austenitic stainless steels (ASS) are extensively employed in various sectors such as nuclear, power, petrochemical, oil and gas because of their excellent structural strength and resistance to corrosion. SS304 and SS316 are the predominant choices for piping, pressure vessels, heat exchangers, nuclear reactor core components and support structures, but they are susceptible to stress corrosion cracking (SCC) in chloride-rich environments. Over the course of several decades, extensive research efforts have been directed towards evaluating SCC using diverse methodologies and models, albeit some uncertainties persist regarding the precise progression of cracks. This review paper focuses on the application of Acoustic Emission Technique (AET) for assessing SCC damage mechanism by monitoring the dynamic acoustic emissions or inelastic stress waves generated during the initiation and propagation of cracks. AET serves as a valuable non-destructive technique (NDT) for in-service evaluation of the structural integrity within operational conditions and early detection of critical flaws. By leveraging the time domain and time-frequency domain techniques, various Acoustic Emission (AE) parameters can be characterized and correlated with the multi-stage crack damage phenomena. Further theories of the SCC mechanisms are elucidated, with a focus on both the dissolution-based and cleavage-based damage models. Through the comprehensive insights provided here, this review stands to contribute to an enhanced understanding of SCC damage in stainless steels and the potential AET application in nuclear industry.

Evaluation of 475 ℃ embrittlement in UNS S32750 super duplex stainless steel using four-point electric conductivity measurements

  • Gutierrez-Vargas, Gildardo;Ruiz, Alberto;Lopez-Morelos, Victor H.;Kim, Jin-Yeon;Gonzalez-Sanchez, Jorge;Medina-Flores, Ariosto
    • Nuclear Engineering and Technology
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    • v.53 no.9
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    • pp.2982-2989
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    • 2021
  • One of the consequences of the 475 ℃ embrittlement of duplex stainless steels is the reduction of the resistance to localized corrosion. Therefore, the detection of this type of embrittlement before the material exhibits significant loss in toughness, and corrosion resistance is important to ensure the structural integrity of critical components under corrosion threats. In this research, conductivity measurements are performed using the alternating current potential drop (ACPD) technique with using a portable four-point probe as a nondestructive evaluation (NDE) method for detecting the embrittlement in a 2507 (UNS S32750) super duplex stainless steel (SDSS) aged at 475 ℃ from as-received condition to 300 h. The electric conductivity results were compared against two electrochemical tests namely double loop electrochemical potentiokinetic reactivation (DL-EPR) and critical pitting temperature (CPT). Mechanical tests and the microstructure characterized using scanning electron microscopy (SEM) imaging are conducted to track the progress of embrittlement. It is shown that the electric conductivity correlates with the changes in impact energy, microhardness, and CPT corrosion tests result demonstrating the feasibility of the four-point probe as a possible field-deployable method for evaluating the 475 ℃ embrittlement of 2507 SDSS.

Finite Element Analysis of Stress and Strain Distribution on Thin Disk Specimen for SCC Initiation Test in High Temperature and Pressure Environment (고온 고압 응력부식균열 개시 시험용 디스크 시편의 응력과 변형에 대한 유한요소 해석)

  • Tae-Young Kim;Sung-Woo Kim;Dong-Jin Kim;Sang-Tae Kim
    • Corrosion Science and Technology
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    • v.22 no.1
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    • pp.44-54
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    • 2023
  • The rupture disk corrosion test (RDCT) method was recently developed to evaluate stress corrosion cracking (SCC) and was found to have great potential for the real-time detection of SCC initiation in a high temperature and pressure environment, simulating the primary water coolant of pressurized water reactors. However, it is difficult to directly measure the stress applied to a disk specimen, which is an essential factor in SCC initiation. In this work, finite element analysis (FEA) was performed using ABAQUSTM to calculate the stress and deformation of a disk specimen. To determine the best mesh design for a thin disk specimen, hexahedron, hex-dominated, and tetrahedron models were used in FEA. All models revealed similar dome-shaped deformation behavior of the disk specimen. However, there was a considerable difference in stress distribution in the disk specimens. In the hex-dominated model, the applied stress was calculated to be the maximum at the dome center, whereas the stress was calculated to be the maximum at the dome edge in the hexahedron and tetrahedron models. From a comparison of the FEA results with deformation behavior and SCC location on the disk specimen after RDCT, the most proper FE model was found to be the tetrahedron model.

Prevention of Soil Contamination from Underground Storage Facilities of Petroleum Product and Hazardous Chemical Compounds (유류 및 유해화학물질 저장시설에서의 토양오염 방지대책)

  • 배우근;홍종철;정진욱;김종호
    • Journal of Soil and Groundwater Environment
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    • v.7 no.4
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    • pp.40-47
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    • 2002
  • The practices of the construction and management of the petroleum and hazardous chemical compound storage facilities in Korea were investigated extensively, and the problems were identified. The advanced technologies in the U.S.A were comparatively studied. Considering the effectiveness of leak prevention and applicability, the following measures were suggested. To prevent corrosion of a tank, a clad tank, an interior lining tank, or a double-wall tank were thought to be the most cost effective. For piping. use of non-metalic materials was suggested. A catchment basin seemed to be effective for preventing spills. For monitoring of leaks, constructions of more than one of detection systems, such as an automatic leak detection device. a vapor detection system, a groundwater monitoring system, or a double-wall monitoring system, were recommended.

Automatic Ultrasonic Inspection on Heater Sleeves and J-Groove Welds of Pressurizer (가압기 전열기 슬리브 및 J-Groove 용접부의 자동 초음파검사)

  • Ryu, Sung Woo;Chang, Hee Jun;Kim, Sun Je;Lee, Sang Duck;Sung, Jong Hwan
    • Transactions of the Korean Society of Pressure Vessels and Piping
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    • v.6 no.2
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    • pp.20-27
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    • 2010
  • In order to prevent the corrosion of component contacted primary water designed alloy 600 material in the nuclear power plant. But the primary water stress corrosion cracking(PWSCC) of alloy 600 and weld area occurs continuously due to the residual stress. The leakage accident resulted from PWSCC in the drain nozzle of the steam generator of domestic power plants. Heater sleeves of the pressurizer are welded with alloy 600 weld material and therefore exposed to the primary water environment. PWSCC occurred in heater sleeve material and weld area of many foreign power plants. The current issue of domestic nuclear power plants are consequently concentrated to PWSCC of similar material. In order to improve the detection and the sizing of the PWSCC in the welding sleeve of the pressurizer, the automatic UT system and multi-directions probe sets have been developed. The experimental studies have been performed using the mock-up block containing artificial reflectors(ID connected EDM notch) and semi-artificial cracks made from thermal fatigue. The automatic UT System is applied in the detection and the length sizing of the ID/OD on the tube and the J-groove weld area of the artificial reflectors and results of the detection and the sizing are compared respectively. Also, the developed automatic UT system is successfully accomplished to inspect the heater sleeve and the J-groove weld area on the pressurizer for the detection of PWSCC.

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Non-contact Ultrasonic Technique for the Thin Defect Evaluation by the Lamb-EMAT (비접촉 Lamb-EMAT를 이용한 두께감육 평가에 관한 연구)

  • Kim, Tae-Hyeong;Park, Ik-Geun;Lee, Cheol-Gu;Kim, Yong-Gwon;Kim, Hyeon-Muk;Jo, Yong-Sang
    • Proceedings of the KWS Conference
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    • 2005.06a
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    • pp.194-196
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    • 2005
  • Ultrasonic guided waves are gaining increasing attention for the inspection of platelike and rodlike structures. At the same time, inspection methods that do not require contact with the test piece are being developed for advanced applications. This paper capitalizes on recent advances in the areas of guided wave ultrasonics and noncontact ultrasonics to demonstrate a superior method for the nondestructive detection of thinning defects simulating hidden corrosion in thin aluminum plates. The proposed approach uses EMAT(electro-magnetic acoustic transducer) for the noncontact generation and detection of guided plate waves. Interesting features in the dispersive behavior of selected guided modes are used for the detection of plate thinning. It is shown that mode cutoff measurements provide a qualitative detection of thinning defects. Measurement of the mode group velocity can be also used to quantify of thinning depth.

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Evaluation of Corrosion Protection Efficiency and Analysis of Damage Detectability in Buried Pipes of a Nuclear Power Plant with 3D FEM (3D FEM 모델링을 이용한 원전 매설배관의 방식성능 평가 및 결함탐지능 분석)

  • Chang, Hyun Young;Park, Heung Bae;Kim, Ki Tae;Kim, Young Sik;Jang, Yoon Young
    • Transactions of the Korean Society of Pressure Vessels and Piping
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    • v.11 no.2
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    • pp.61-67
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    • 2015
  • 3D FEM modeling based on 3D CAD data has been performed to evaluate the efficiency of CP system in a real operating nuclear power plant. The results of it successfully produced sophisticated profiles of electrolytic potential and current distributions in the soil of an interested area. This technology is expected to be a breakthrough for detection technology of damages on buried pipes when it comes into combining with a brand of area potential earth current (APEC) and ground penetrated radar (GPR) technologies. 2D current distribution and 2D current vectors on the earth surface from the APEC survey will be used as boundary conditions with exact 3D geometry data resulting in visualization of locations and extents of corrosion damages on the buried pipes in nuclear power plants.

Ultrasonics and electromagnetics for a wireless corrosion sensing system embedded in structural concrete

  • Hietpas, K.;Ervin, B.;Banasiak, J.;Pointer, D.;Kuchma, D.A.;Reis, H.;Bernhard, J.T.
    • Smart Structures and Systems
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    • v.1 no.3
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    • pp.267-282
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    • 2005
  • This work describes ongoing development of an embedded sensor system for the early detection and prevention of deterioration of reinforcing steel tendons within reinforced concrete. These devices will evaluate the condition of the steel tendon using ultrasonic techniques and then wirelessly transmit this data to the outside world without human intervention. The ultrasonic transducers and the interpretation of the sensed signals that allow detection and prognosis of tendon condition are detailed. Electrical characterization of concrete mixtures used in bridge construction is conducted and a wideband microstrip antenna is designed and fabricated to operate between 2.4 and 2.5 GHz when embedded in such a medium. Simulations and measurements of the embedded antenna element are presented. Transceiver selection and implementation are discussed as well as future work in operational protocols, sensor networking, and power sources. By implementing commercially available off-the-shelf components whenever possible, these devices have the potential to save millions of dollars a year in evaluation, repair and replacement of reinforced concrete.