• Title/Summary/Keyword: conductance

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Development of a Simplified Fuel-Cladding Gap Conductance Model for Nuclear Feedback Calculation in 16$\times$16 FA

  • Yoo, Jong-Sung;Park, Chan-Oh;Park, Yong-Soo
    • Proceedings of the Korean Nuclear Society Conference
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    • 1995.05a
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    • pp.636-643
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    • 1995
  • The accurate determination of the fuel-cladding gap conductance as functions of rod burnup and power level may be a key to the design and safety analysis of a reactor. The incorporation of a sophisticated gap conductance model into nuclear design code for computing thermal hydraulic feedback effect has not been implemented mainly because of computational inefficiency due to complicated behavior of gap conductance. To avoid the time-consuming iteration scheme, simplification of the gap conductance model is done for the current design model. The simplified model considers only the heat conductance contribution to the gap conductance. The simplification is made possible by direct consideration of the gas conductivity depending on the composition of constituent gases in the gap and the fuel-cladding gap size from computer simulation of representative power histories. The simplified gap conductance model is applied to the various fuel power histories and the predicted gap conductances are found to agree well with the results of the design model.

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Preliminary Study for the Development of Optimum Fuel Contact Conductance Model (최적 핵연료 접촉 열전도도 모델 개발을 위한 예비 연구)

  • Yang, Yong-Sik;Shin, Chang-Hwan
    • Proceedings of the KSME Conference
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    • 2007.05b
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    • pp.2488-2493
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    • 2007
  • A gap conductance is very important factor which can affect nuclear fuel temperature. Especially, in case of an annular fuel, a gap conductance effect can lead an unexpected heat split phenomena which is caused by a large difference of an inner and outer gap conductance. The gap conductance mechanism is very complicated behavior due to the its strong dependency on microscopic factors such as a contact surface roughness, local contact pressure and local temperature. In this paper, for the decision of test temperature and pressure range, a procedure and calculation results of in-reactor fuel temperature and pressure analysis are summarized which can be applied to test equipment design and determination of test matrix. Based upon analysis results, it is concluded that the minimum and maximum test temperature are $300^{\circ}C$ and $530^{\circ}C$ respectively, and the maximum pellet/cladding interfacial contact pressure should be observed up to 45MPa.

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Real-time measurement of void fraction and its propagation speed of slug flow with two Conductance meters (두 개의 컨덕턴스미터를 이용한 슬러그류의 기공률 및 기공률 전달속력 실시간 측정)

  • Kim, Jong-Rok;Ahn, Yeh-Chan;Kang, Deok-Hong;Kim, Moo-Hwan
    • Proceedings of the KSME Conference
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    • 2004.11a
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    • pp.1569-1573
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    • 2004
  • Two ring-type conductance meters were manufactured to measure void fraction and its propagation speed in slug flow. The signal of conductance meter with two rings depends on liquid temperature. Therefore a conductance meter with separated probe designed by Coney (1973), which is independent of liquid temperature, was used and experimentally proved. The manufactured conductance meters showed a good repeatability and agreement with the analytical solution by Coney (1973). From time lag between two conductance meter, we could calculate the propagation speed of void fraction.

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Electronic Ballast Design for Ceramic MHL by using Its Conductance Model (세라믹 MHL의 컨덕턴스 모델을 이용한 전자식 안정기 설계)

  • Park, Chong-Yeon;Shin, Dong-Seok
    • Journal of Industrial Technology
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    • v.28 no.B
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    • pp.117-122
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    • 2008
  • This paper presents the conductance model at high frequency of the Ceramic Metal Halide Lamp and the designing method of the electronic ballast with the LCC resonant tank type by using that model. Conductance model is based on a physical phenomenon in the discharge tube of the lamp and model constants of conductance model are obtained by Least Squares Method. After equivalent impedances are determined by the conductance model, The LCC resonance tank is designed by using the equation of the lamp power. Simulation result using PSpice software and experimental results show that the conductance model in this paper is very useful to design the electronic ballast at high frequency for the Ceramic Metal Halide Lamps.

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Effect of Gas Beaming in the Calculation of Tube Conductance (Beaming Effect를 고려한 Tube 연결부의 Conductance 계산)

  • 이진원;이영규
    • Journal of the Korean Vacuum Society
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    • v.1 no.1
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    • pp.16-23
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    • 1992
  • Conductance calculation is essential in designing a vacuum system. Since mathematical solution is nearly impossible except for a few simple cases, it has been so usual to calculate the conductance for a series connection of components using an approximate formula by Oatley. However, Oatley's formula has a fundamental flaw of totally neglecting the effect of gas beaming. In this study, a new technique is suggested for calculating the conductance with the same accuracy as the Monte Carlo method but with much less computing time, and applied to a system of tube connections in series. The effects of gas beaming in the calculation of conductance is analyzed quantitatively by comparing the conductance calculated by this method with those from Oatley's formula.

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A NOTE ON CONDUCTANCE METHOD IN Rn

  • Chung, Bo-Hyun;Jung, Wan-Soo
    • Journal of the Chungcheong Mathematical Society
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    • v.18 no.2
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    • pp.205-213
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    • 2005
  • We introduce the conductance and examine its properties. We study the local behavior of quasiconformal mappings on the boundary of a domain $D{\subset}\overline{R}^n$ n and present some geometric applications of conductance.

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The Characterization of the Increase of Membrane Conductance after Depolarization in Single Rat Adrenal Chromaffin Cells

  • Lim, Won-Il;Kim, Sang-Jeong;Kim, Jun
    • The Korean Journal of Physiology and Pharmacology
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    • v.2 no.1
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    • pp.95-100
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    • 1998
  • The conductance change evoked by step depolarization was studied in primarily cultured rat adrenal chromaffin cells using patch-clamp and capacitance measurement techniques. When we applied a depolarizing pulse to a chromaffin cell, the inward calcium current was followed by an outward current and depolarization-induced exocytosis was accompanied by an increase in conductance trace. The slow inward tail current which has the same time course as the conductance change was observed in current recording. The activation of slow tail current was calcium-dependent. Reversal potentials agreed with Nernst equation assuming relative permeability of $Cs^+\;to\;K^+$ is 0.095. The outward current and tail current were blocked by apamin (200 nM) and d-tubocurarine (2 mM). The conductance change was blocked by apamin and did not affect membrane capacitance recording. We confirmed that conductance change after depolarization comes from the activation of the SK channel and can be blocked by application of the SK channel blockers. Consequently, it is necessary to consider blocking of the SK channel during membrane capacitance recording.

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An experimental study on heat transfer characteristics of variable conductance heat pipe (가변전열 히이트 파이프의 특성에 관한 연구)

  • 김주년;이영호;김용모
    • Journal of Advanced Marine Engineering and Technology
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    • v.8 no.1
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    • pp.4-16
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    • 1984
  • The heat-pipe is characterised by the highly effective thermal conductance. In order to change the thermal conductance, the heat-pipe is connected to a reservior having a space which is filled with non-condensable gas. In normal operation, the vapour of working fluid will tend to pump the non- condensable gas into the reservoir and the gas-vapour interface situates at some point along the condenser section. The thermal conductance is affected by non- condensable gas. It is concluded that the suitable position of interface can be used to control the temperature of condenser section. In this experiment, the evaporating part is connected to the lowest position of heat-pipe. The copper heat-pipe which is filled with Freon-113 or distilled water as working fluid utilized. As results of experimental study, thermal conductance can be increased by the operating pressure which is infulenced by non-condensable gas. A correlative equation between the thermal conductance and the mass of non- condensable gas is also obtained.

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Input conductance of neuron for Hopfield Neural Networks (Hopfield 신경회로망에서 뉴론의 입력단 컨덕턴스)

  • Kang, Min-Je
    • Journal of IKEEE
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    • v.4 no.2 s.7
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    • pp.192-201
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    • 2000
  • This paper discusses the influence of the input conductance on system stability for the continuous type Hopfield Neural Networks.. The input conductance is connected from the neuron input to ground. The input conductance has been proved to effect on stability in input space. Transient analysis is used to test the stability in input space. Also, it has been studied how to adjust the input conductance for improving the system's performance.

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A study on the impedance effect of nonvolatile memory devices (비휘발성 기억소자의 저항효과에 관한 연구)

  • 강창수
    • Electrical & Electronic Materials
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    • v.8 no.5
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    • pp.626-632
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    • 1995
  • In this paper, The effect of the impedances in SNOSFET's memory devices has been developed. The effect of source and drain impedances measured by means of two bias resistances - field effect bias resistance by inner region, external bias resistance. The effect of the impedances by source and drain resistance shows the dependence of the function of voltages applied to the gate. It shows the differences of change in source drain voltage by means of low conductance state and high conductance state. It shows the delay of threshold voltages. The delay time of low conductance state and high conductance state by the impedances effect shows 3[.mu.sec] and 1[.mu.sec] respectively.

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