• Title/Summary/Keyword: Corrosion Model

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CFD Analysis to Suppress Condensate Water Generated in Gas Sampling System of HANARO (하나로 기체시료채취계통에서 생성된 응축수 억제를 위한 CFD 해석)

  • Cho, SungHwan;Lee, JongHyeon;Kim, DaeYoung
    • Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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    • v.18 no.2_spc
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    • pp.327-336
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    • 2020
  • The high-flux advanced neutron application reactor (HANARO) is a research reactor with thermal power of 30 MW applied in various research and development using neutrons generated from uranium fission chain reaction. A degasifier tank is installed in the ancillary facility of HANARO. This facility generates gas pollutants produced owing to internal environmental factors. The degasifier tank is designed to maintain the gas contaminants below acceptable levels and is monitored using an analyzer in the gas sampling panel. If condensate water is generated and flows into the analyzer of the gas sampling panel, corrosion occurs inside the analyzer's measurement chamber, which causes failure. Condensate water is generated because of the temperature difference between the degasifier tank and analyzer when the gas flows into the analyzer. A heating system is installed between the degasifier tank and gas sampling panel to suppress condensate water generation and effectively remove the condensate water inside the system. In this study, we investigated the efficiency of the heating system. In addition, the variations in the pipe temperature and the amount of average condensate water were modeled using a wall condensation model based on the changes in the fluid inlet temperature, outside air temperature, and heating cable-setting temperature.

Fretting Wear Characteristics of the Corroded Fuel Cladding Tubes for Nuclear Fuel Rod against Supporting Girds (부식된 핵연료 피복관과 지지격자 사이의 프레팅 마멸 특성)

  • Kim, Jin-Seon;Park, Se-Min;Kim, Yong-Hwan;Lee, Seung-Jae;Lee, Young-Ze
    • Tribology and Lubricants
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    • v.23 no.3
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    • pp.130-133
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    • 2007
  • Fuel cladding tubes in nuclear fuel assembly are held up by supporting grids because the tubes are long and slender. Fluid flows of high-pressure and high-temperature in the tubes cause oscillating motions between tubes and supports. This is called as FIV (flow induced vibration), which causes fretting wear in contact parts of tube and support. The fretting wear of tube and support can threaten the safety of nuclear power plant. Therefore, a research about the fretting wear characteristics of tube-support is required. The fretting wear tests were performed with supporting grids and cladding tubes, especially after corrosion treatment on tubes, in water. The tests were done using various applied loads with fixed amplitude. From the results of fretting tests, the wear amounts of tube materials can be predictable by obtaining the wear coefficient using the work rate model. Due to stick phenomena the wear depth was changed as increasing load and temperature. The maximum wear depth was decreased as increasing the water temperatures. At high temperatures there are the regions of some severe adhesion due to stick phenomena.

Fretting Wear Characteristics of the Corroded Fuel Cladding Tubes for Nuclear Fuel Rod against Supporting Girds (부식된 핵연료 피복관과 지지격자 사이의 프레팅 마멸 특성)

  • Lee, Young-Ze;Kim, Jin-Seon;Park, Se-Min;Kim, Yong-Hwan;Lee, Seung-Jae
    • Tribology and Lubricants
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    • v.24 no.3
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    • pp.129-132
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    • 2008
  • Fuel cladding tubes in nuclear fuel assembly are held up by supporting grids because the tubes are long and slender. Fluid flows of high-pressure and high-temperature in the tubes cause oscillating motions between tubes and supports. This is called as FIV (flow induced vibration), which causes fretting wear in contact parts of tube and support. The fretting wear of tube and support can threaten the safety of nuclear power plant. Therefore, a research about the fretting wear characteristics of tube-support is required. The fretting wear tests were performed with supporting grids and cladding tubes, especially after corrosion treatment on tubes, in water. The tests were done using various applied loads with fixed amplitude. From the results of fretting tests, the wear amounts of tube materials can be predictable by obtaining the wear coefficient using the work rate model. Due to stick phenomena the wear depth was changed as increasing load and temperature. The maximum wear depth was decreased as increasing the water temperatures. At high temperatures there are the regions of some severe adhesion due to stick phenomena.

Crashworthiness Evaluation of Bridge Barriers Built with Hot-dip Zinc-aluminium-magnesium Alloy-coated Steel (고내식성 용융합금도금강판 적용 교량난간의 충돌성능 평가)

  • Noh, Myung-Hyun
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.17 no.3
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    • pp.171-176
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    • 2016
  • This paper proposes road safety facilities applying Hot-dip zinc-aluminum-magnesium alloy-coated steel sheets and coils to reduce the loss of function caused by the corrosion of steel in the service state. Vehicle crash simulations and full-scale crash tests were carried out to provide reliable information on evaluating the crash performance with the products of road safety facilities built with hot-dip zinc-aluminum-magnesium alloy-coated steel. From the results of the simulations and full-scale crash tests, the impact behaviors evaluated by the three-dimensional crash simulations considering the strain-rate dependency in a constitutive model were similar to those obtained from the full-scale crash test results. The full-scale crash test results met the crashworthiness evaluation criteria; hence, the proposed bridge barrier in this paper is ready for field applications.

Evaluation of press formability of pure titanium sheet (순 티탄늄 판재의 프레스 성형성 평가(제 1보))

  • Kim, Young-Suk;In, Jeong-Hun
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.17 no.3
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    • pp.380-388
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    • 2016
  • Commercially pure titanium (CP Ti) has been actively used in plate heat exchangers due to its light weight, high specific strength, and excellent corrosion resistance. However, compared with automotive steels and aluminum alloys, there has not been much research on the plastic deformation characteristics and press formability of CP Ti sheet. In this study, the mechanical properties of CP Ti sheet are clarified in relation to press formability, including anisotropic properties and the stress-strain relation. The flow curve of the true stress-true strain relation is fitted well by the Kim-Tuan hardening equation rather than the Voce and Swift models. The forming limit curve (FLC) of CP Ti sheet was experimentally evaluated as a criterion for press formability by punch stretching tests. Analytical predictions were also made via Hora's modified maximum force criterion. The predicted FLC with the Kim-Tuan hardening model and an appropriate yield function shows good correlation with the experimental results of the punch stretching test.

Heat Pump System Using Heated Effluent of Thermal Power Generation Plant as a Heat Source (해수를 이용한 화력발전소 폐열회수 히트펌프 시스템)

  • Ryou, Y.S.;Kang, Y.K.;Kim, Y.H.;Jang, J.K.;Kim, J.G.;Lee, H.M.;Kang, G.C.;Nah, K.D.;Huh, T.H.
    • 한국신재생에너지학회:학술대회논문집
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    • 2011.05a
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    • pp.190-190
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    • 2011
  • In South Korea the gross generation and heated effluent of power generation plant was 259 TWh and 4.73 billion tons in 2008. And then the waste heat from power generation was 388 TWh. It shows that the efficiency of thermal power generation plant is about 40%. Therefore to reduce $CO_2$ emission from thermal power generation plant, the energy of this heated effluent must be reused to heat buildings or farm facilities. In South Korea horticultural facilities of about 25% are heated in winter season. Total area of greenhouses which are heated is about 13,000 ha. Total heat amount needed to warm greenhouse of 13,000 ha in winter season is only 3.4% of total waste heat from power generation plant. In this study a heat pump system was designed to reuse the waste heat from power generation. Especially new heat exchanger was developed to recover the thermal energy from waste water and this model considered anti-corrosion against sea water and low cost for economic feasibility. This heat recovery system was installed in mango growing greenhouse around thermal power generation plant in Seogwipo-city, Jeju Special Self-Governing Province. The result of preliminary test shows that the heating cost of about 90% is saved as compared to boiler using tax free light oil as a fuel.

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Prediction of Deterioration Process for Concrete Considering Combined Deterioration of Carbonation and Chlorides Ion (중성화와 염해를 고려한 콘크리트의 복합열화 예측)

  • Lee, Chang-Soo;Yoon, In-Seok
    • Journal of the Korea Concrete Institute
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    • v.15 no.6
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    • pp.902-912
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    • 2003
  • The most common deteriorating processes of concrete structures are carbonation and chloride ion ingress. Many concrete structures have been suffered from chloride ions diffusion or carbonation induced reinforcement corrosion damage and many studies have been done on it. However, those studies were confined mostly to the single deterioration of carbonation or chloride attack only, although actual environment is rather of combined conditions. In case of many in-situ concrete structures, deterioration happened more for the case of combined attack than the single case of carbonation or chloride attack. In this paper, chloride profiles of carbonated concrete is predicted by considering two layer composite model, which is based on Fick's 2nd law. From the experimental result on combined deterioration of chloride and carbonation, it was examined that high chloride concentration was built up to 3∼5 mm over depth from carbonation depth. The analytical modeling of chloride diffusion was suggested to depict the relative influence of the carbonation depth. The diffusion coefficients of carbonation concrete and uncarbonated concrete with elapsed time were considered in this modeling.

The advancing techniques and sputtering effects of oxide films fabricated by Stationary Plasma Thruster (SPT) with Ar and $O_2$ gases

  • Jung Cho;Yury Ermakov;Yoon, Ki-Hyun;Koh, Seok-Keun
    • Proceedings of the Korean Vacuum Society Conference
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    • 1999.07a
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    • pp.216-216
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    • 1999
  • The usage of a stationary plasma thruster (SPT) ion source, invented previously for space application in Russia, in experiments with surface modifications and film deposition systems is reported here. Plasma in the SPT is formed and accelerated in electric discharge taking place in the crossed axial electric and radial magnetic fields. Brief description of the construction of specific model of SPT used in the experiments is presented. With gas flow rate 39ml/min, ion current distributions at several distances from the source are obtained. These was equal to 1~3 mA/$\textrm{cm}^2$ within an ion beam ejection angle of $\pm$20$^{\circ}$with discharge voltage 160V for Ar as a working gas. Such an extremely high ion current density allows us to obtain the Ti metal films with deposition rate of $\AA$/sec by sputtering of Ti target. It is shown a possibility of using of reactive gases in SPT (O2 and N2) along with high purity inert gases used for cathode to prevent the latter contamination. It is shown the SPT can be operated at the discharge and accelerating boltages up to 600V. The results of presented experiments show high promises of the SPT in sputtering and surface modification systems for deposition of oxide thin films on Si or polymer substrates for semiconductor devices, optical coatings and metal corrosion barrier layers. Also, we have been tried to establish in application of the modeling expertise gained in electric and ionic propulsion to permit numerical simulation of additional processing systems. In this mechanism, it will be compared with conventional DC sputtering for film microstructure, chemical composition and crystallographic considerations.

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Experiment on Flexural Analysis of RC Beams Strengthened with Composite Material Panel (복합재료 패널로 보강된 철근 콘크리트 보의 휨 실험)

  • Kim, Jin-Man;Jung, Mi-Roo;Lee, Jae-Hong;Yoon, Kwang-Sup
    • Journal of Korean Association for Spatial Structures
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    • v.10 no.2
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    • pp.117-126
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    • 2010
  • Experiment on flexural analysis of RC beams strengthened with composite material panel is presented. Recently, the strengthening of reinforced concrete structures using advanced fiber reinforced plastic (FRP) composites, and in particular the behavior of FRP-reinforced concrete structure is topic that has become very popular because of good corrosion resistance and easy for site handling due to their light weight. In this study, an efficient computational analysis using ABAQUS to predict the ultimate moment capacity of reinforced concrete beams strengthened with FRP is presented. Test parameters in this study are the shape of fiber arrangement (LT, DB, DBT) and the number of carbon fiber sheets (2ply, 3ply). When comparing with results of the analytical model, results of the experiments show similar values. Furthermore, reinforced concrete beam with FRP obtains improved effects for ultimate strength.

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The Integrity Verification of Tube-end Sleeve by ECT (와전류탐상검사에 의한 튜브엔드 슬리브 건전성 검증)

  • Kim, Su Jin;Kwon, Kyung Joo;Suk, Dong Hwa;Park, Ki Tae
    • Transactions of the Korean Society of Pressure Vessels and Piping
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    • v.11 no.1
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    • pp.20-24
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    • 2015
  • Steam generator(S/G) tubes in pressurized water reactor (PWR's) are subject to several types of degradation. This degradation includes denting, pitting, intergranular attack(IGA), intergranular stress corrosion cracking(IGSCC), fatigue, fretting and wear. Degradation can be derived from either the primary side(inside) or the secondary side(outside) of the tube. Recent issue for tube degradation in domestic steam generator is the tube end cracking on seal weld region. The seal weld region at the tube end and tube itself is regarded as a pressure boundary between the primary side and the secondary side. One of the Westinghouse Model-F S/G has experienced tube end cracking and its number of plugging approximately becomes to the operating limit up to 5% due to tube end cracking which was reported as SAI/MAI(single/multiple axial indication) or SCI/MCI(Single/multiple circumferential indication) from the results of eddy current testing. Eddy current mock-up test was carried out to determine the origin of cracking whether it is from weld zone area or parent tube. This result was helpful to analyze crack location on ECT data. Correct action on this problem was the installation of tube-end sleeve. Last year, after removing 340 installed plugs from tubes, selected 269 tubes took tube-end sleeve installation. Tube-end sleeve brought pressure boundary from parent tube to installed sleeve tube. Tube-end sleeve has the benefit of reducing outage period and increasing more revenue than replacing S/G. This paper is provided to assist interest parties in effectively understanding this issue.