• Title/Summary/Keyword: Reactor Parameter

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Complex Leakage Probability Evaluation of Nuclear Pipes by Fatigue and Stress Corrosion Cracking (피로 및 응력부식균열에 의한 원전 배관의 복합누설확률 평가)

  • Kim, Seung Hyun;Goni, Nasimul;Chang, Yoon-Suk;Jang, Changheui
    • Transactions of the Korean Society of Pressure Vessels and Piping
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    • v.11 no.2
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    • pp.25-30
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    • 2015
  • In the present study, complex leakage probabilities of nuclear pipes due to fatigue and stress corrosion cracking are evaluated by using the PINTIN(Piping INTegrity INner flaws) that is developed based on the existing PRAISE(Piping Reliability Analysis Including Seismic Events) program. With regard to the aging and crack instability, small leak and big leak probabilities are calculated for several pipes in a reactor coolant system of domestic nuclear plant. Moreover, sensitivity analysis is also performed to find out the effect of parameters for the leakage of pipes, which shows the coolant temperature is the most influencing parameter.

The Effects of Combustion Parameters on the Characteristics of a Steam-Methane Reformer (연소 변수가 수증기-메탄 개질기의 특성에 미치는 영향)

  • Lee, Jae-Seong;Kim, Ho-Young
    • 한국연소학회:학술대회논문집
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    • 2012.04a
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    • pp.29-31
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    • 2012
  • The effects of combustion parameters on the characteristics of a steam-methane reformer. The reformer system was numerically simulated using a simplified two-dimensional axisymmetric model domain with an appropriate user-defined function. The fuel ratio, defined as the ratio of methane flow rate in the combustor to that in the reactor, was varied from 20 to 80%. The equivalence ratio was changed from 0.5 to 1.0. The results indicated that as the fuel ratio increased, the production rates of hydrogen and carbon monoxide increased, although their rates of increase diminished. In fact, at the highest heat supply rates, hydrogen production was actually slightly decreased. Simulations showed that equivalence ratio of 0.7 yielded the highest steam-methane mixture temperature despite a 43% higher air flow rate than the stoichiometric flow rate. This means that the production of hydrogen and carbon monoxide can be increased by adjusting the equivalence ratio, especially when the heat supply is insufficient.

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The Characteristics of Bioremediation for VOCs in Soil Column (VOCs 처리를 위한 미생물의 토양복원화 특성)

  • 손종렬;장명배;조광명
    • Journal of environmental and Sanitary engineering
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    • v.17 no.1
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    • pp.52-56
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    • 2002
  • The study was carried out to evaluate the characteristics of biodegradation by Pseudomonas putida G7 in soil column. The reactor system was used to investigate mass transfer of VOCs as Toluene in a column of unsaturated soil. Determination of the fate of VOCs in unsaturated soil is necessary to evaluate the feasibility of natural attenuation as a VOCs remediation strategy. The objective of this study was to develop a mechanistically based mathematical model that would consider the interdependence of VOC transport, microbial activity, and sorptive interactions in a moist, unsaturated soil. Because the focus of the model was on description of natural attenuation, the advective VOCs transport that is induced in engineered remediation processes such as vapor extraction was not considered. It can be concluded that the coefficient for gas liquid mass-transfer was found to be a key parameter controlling the ability of bacteria to VOCs. Finally, it appeared that bioremediation technology of VOCs which are difficult to be decomposed by chemical methods.

Parametric Study on Earthquake Responses of Soil-structure Interaction System by Substructure Method. (부분구조법에 의한 지반-구조물 상호작용 시스템의 지진응답 매재변수 해석)

  • 조양희
    • Proceedings of the Earthquake Engineering Society of Korea Conference
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    • 1997.10a
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    • pp.117-125
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    • 1997
  • ABSTRACT This paper presents results of parametric studies of the seismic responses of a reactor containment structure on layered base soil. Among the numerous parameters, this study concentrates on the effects of embedment of structure to the base soil, thickness of the soil layers, stiffness of the base soil, and the definition point of the input motion. For the analysis, a substructure method using frequency independent impedances is adopted. The method is based on the mode superposition method in time domain using the composite modal damping values of the SSI system computed from the ratio of dissipated energy to the strain energy for each mode. From the study results, the sensitives of each parameter on the earthquake responses have been suggested for the practical application of the substructure method of SSI analysis.

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An Analysis of a Post-Trip Return-to-Power Steam Line break Events

  • Baek, Seung-Su;Lee, Cheol-Sin;Song, Jin-Ho;Lee, Sang-Yong
    • Proceedings of the Korean Nuclear Society Conference
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    • 1995.05a
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    • pp.544-549
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    • 1995
  • An analysis for Steam Line Break (SLB) events which result in a return-to-power conditions after reactor trip was performed for a postulated Yonggwang Nuclear Power Plant Unit 3 cycle 8. Analysis methodology for post-trip return-to-power SLB is quite different from that of a no return-to-power SLB and is more complicated. Therefore, it is necessary to develop an methodology to analyze the response of the NSSS parameter and the fuel performance for the post-trip return-to-power SLB events. In this analysis, the cases with and without offsite power were simulated by crediting 3-D reactivity feedback effect due to local heatup around stuck CEA and compared with the cases without 3-D reactivity feedback with respect to fuel performance, departure from nucleate boiling ratio (DNBR) and linear heat generation rate (LHGR).

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Statistical Evaluation of Fracture Characteristics of RPV Steels in the Ductile-Brittle Transition Temperature Region

  • Kang, Sung-Sik;Chi, Se-Hwan;Hong, Jun-Hwa
    • Nuclear Engineering and Technology
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    • v.30 no.4
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    • pp.364-376
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    • 1998
  • The statistical analysis method was applied to the evaluation of fracture toughness in the ductile-brittle transition temperature region. Because cleavage fracture in steel is of a statistical nature, fracture toughness data or values show a similar statistical trend. Using the three-parameter Weibull distribution, a fracture toughness vs. temperature curve (K-curve) was directly generated from a set of fracture toughness data at a selected temperature. Charpy V-notch impact energy was also used to obtain the K-curve by a $K_{IC}$ -CVN (Charpy V-notch energy) correlation. Furthermore, this method was applied to evaluate the neutron irradiation embrittlement of reactor pressure vessel (RPV) steel. Most of the fracture toughness data were within the 95% confidence limits. The prediction of a transition temperature shift by statistical analysis was compared with that from the experimental data.

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Analysis of spray sodium fire phenomena in the containment vessel (격납용기내에서 분무형 나트륨화재 현상 해석)

  • 조병렬;권선길;황성태
    • Journal of the Korean Society of Safety
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    • v.11 no.2
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    • pp.79-88
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    • 1996
  • A hypothetical accident in the containment vessel of liquid metal reactor could cause a pressure, temperature rise, and a strong aerosol release. The computer codes relating to the modelization of these accident make it necessary to use various input parameter, among which is the dynamic shape factor of aerosols produced. Combustion experiments of sodium spray fire carried out in a closed vessel, which was vertical cylinder made of 1.2m in diameter and 1.8m hight with a volume of 1.7$m^3$. The results of theoretical analysis presented here was compared to data obtained from experiments. The experimental results were summarized as follows. 1) The aerodynamic diameter and geometric diameter of aerosols are decreasing with increasing of injection pressure and injection temperature of sodium 2) The dynamic shape factor of aerosol is proportional to the aerodynamic diameter for a given particle. 3) The correspondence between the aerodynamic diameter and geometric diameter can be as $D_{ae}=0.70 D_{ge}$. 4) Peak pressure rose with increase in pressure and temperature of injection sodium, being more sensitive to the injection pressure than the injection temperature.

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Application of Self Tuning Fuzzy Controller for System Stability Improvement (시스템 안정도 개선을 위한 자기조정 퍼지제어기 적용)

  • Hur, Dong-Ryol;Joo, Seok-Min;Kim, Hai-Jai
    • Proceedings of the KIEE Conference
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    • 2002.06a
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    • pp.60-63
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    • 2002
  • This paper presents a control approach for designing a self tuning fuzzy controller for SVC system, A SVC constructed by a Fixed Capacitor and a Thyristor Controlled Reactor is designed and implemented to improve the damping of a synchronous generator, as well as controlling the system voltage, The proposed parameter self tuning algorithm of fuzzy controller is based on the steepest decent method using two direction vectors which make error between inference values of fuzzy controller and output values of the specially selected PSS reduce steepestly, The related simulation results show that the proposed fuzzy controller is more powerful than the conventional ones.

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Flux Density Analysis of Linear Induction Electromagnetic Pumps for Liquid Metal (액체 금속 구동용 선형유도전자램프의 자속밀도 분포 해석)

  • Jang, Nam-Young;Eun, Jae-Jung;Park, Tae-Bong;Choi, Hun-Gi;Yoo, Geun-Jong
    • Proceedings of the KIEE Conference
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    • 2003.07b
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    • pp.906-908
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    • 2003
  • A Linear induction electromagnetic(EM) pump of liquid metal fast breeder reactor(LMFBR) is used for the purpose that the liquid metal of high temperature is transported by EM force. This paper evaluates magnetic flux density necessary for transporting liquid metal, using analytical model of the linear induction EM pump. Using the 2-D finite element method(2-D FEM), magnetic flux density is estimated in consideration of a geometric model, electric parameter, and velocity of liquid metal. From the viewpoint of hydrodynamics, the results can be used for flow analysis of the liquid metal.

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Effect of Process Parameters of UV Enhanced Gas Phase Cleaning on the Removal of PMMA (Polymethylmethacrylate) from a Si Substrate

  • Kwon, Sung Ku;Kim, Do Hyun
    • Transactions on Electrical and Electronic Materials
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    • v.17 no.4
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    • pp.204-207
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    • 2016
  • Experimental study of UV-irradiated O2/H2 gas phase cleaning for PMMA (Polymethylmethacrylate) removal is carried out in a load-locked reactor equipped with a UV lamp and PBN heater. UV enhanced O2/H2 gas phase cleaning removes polymethylmethacrylate (PMMA) better at lower process pressure with higher content of H2. O2 gas compete for UV (184.9 nm) absorption with PMMA producing O3, O(1D) and lower dissociation of PMMA. In our experimental conditions, etching reaction of PMMA at the substrate temperature between 75℃ and 125℃ had activation energy of about 5.86 kcal/mol indicating etching was controlled by surface reaction. Above the 180℃, PMMA removal was governed by a supply of reaction gas rather than by substrate temperature.