• Title/Summary/Keyword: Fuel eccentricity

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Investigation on the effect of eccentricity for fuel disc irradiation tests

  • Scolaro, A.;Van Uffelen, P.;Fiorina, C.;Schubert, A.;Clifford, I.;Pautz, A.
    • Nuclear Engineering and Technology
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    • v.53 no.5
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    • pp.1602-1611
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    • 2021
  • A varying degree of eccentricity always exists in the initial configuration of a nuclear fuel rod. Its impact on traditional LWR fuel is limited as the radial gap closes relatively early during irradiation. However, the effect of misalignment is expected to be more relevant in rods with highly conductive fuels, large initial gaps and low conductivity filling gases. In this paper, we study similar characteristics in the experimental setup of two fuel disc irradiation campaigns carried out in the OECD Halden Boiling Water Reactor. Using the multi-dimensional fuel performance code OFFBEAT, we combine 2-D axisymmetric and 3-D simulations to investigate the effect of eccentricity on the fuel temperature distribution. At the same time, we illustrate how the advent of modern tools with multi-dimensional capabilities might further improve the design and interpretation of in-pile separate-effect tests and we outline the potential of such an analysis for upcoming experiments.

Influence of Pyrolyzing Fuel Disposition on Combustion Phenomena in a Cylindrical Enclosure (원형공간내 열분해 연료의 공간배치가 연소현상에 미치는 영향)

  • Han, Cho-Young;Kim, Jeong-Soo
    • Proceedings of the KSME Conference
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    • 2000.11b
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    • pp.680-685
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    • 2000
  • Investigation on ignition and flame propagation of pyrolyzing fuel in a cylindrical enclosure is accomplished. The pyrolyzing fuel of cylindrical shape is located in an outer cylinder sustained at high-temperature. Due to gravity, the buoyancy motion is inevitably incurred in the enclosure and this affects the flame initiation and propagation behavior. The radiative heat transfer plays an important role since a high temperature difference is involved in the problem. Numerical studies have been performed over overheat ratio, and vertical fuel eccentricity. The location of flame onset is affected by the vertical eccentricity of inner pyrolyzing fuel as well as thermal conditions applied.

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The Effects of Fuel Pellet Eccentricity on Fuel Rod Thermal Performance (핵연료의 편심이 연료봉 열적 성능에 미치는 영향)

  • Suh Young-Keun;Sohn Dong-Seong
    • Nuclear Engineering and Technology
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    • v.20 no.3
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    • pp.189-196
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    • 1988
  • This study investigates the effect of fuel pellet eccentricity on fuel rod thermal performance under the steady state condition. The governing equations in the fuel pellet and the cladding region are set up in 2-dimensional cylindrical coordinate (r, $\theta$) and are solved by finite element method. The angular-dependent heat transfer coefficient in the gap region is used in order to account for the asymmetry of gap width. Material propeties are used as a function of temperature and volumetric heat generation as a function of radial position. The results show the increase of maximum local heat flux at the cladding outer surface and the decrease of maximum and average fuel temperatures due to eccentricity. The former is expected to affect the uncertainties in the minimum DNBR calculation. The latter two are expected to reduce the possibility of fuel melting and the fuel stored energy. Also, the fuel pellet eccentricity introduces asymmetry in fuel pellet temperature and movement of the location of maximum fuel pellet temperature.

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Effect of Pyrolyzing Fuel Position on Ignition and Flame Propagation in a Cylindrical Enclosure (원형공간내 열분해 연료의 위치변화에 따른 점화 및 화염전파 영향)

  • Han, Jo-Yeong;Kim, Jeong-Su
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.25 no.1
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    • pp.133-142
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    • 2001
  • Investigation on ignition and flame propagation of pyrolyzing fuel in a cylindrical enclosure is accomplished. The pyrolyzing fuel of cylindrical shape is located in an outer cylinder sustained at high-temperature. Due to gravity, the buoyancy motion is inevitably incurred in the enclosure and this affects the flame initiation and propagation behavior. The radiative heat transfer plays an important role since a high temperature difference is involved in the problem. Therefore in all cases presented here, the intrinsic radiation effects are considered. Numerical studies have been performed over various governing parameters, such as Grashof number, overheat ratio, and vertical fuel eccentricity. Depending on the Grashof number, the flame behavior is found to be totally different: a separated visible flame appears as the Grashof number reaches 10(sup)7. The location of flame onset is also affected by the vertical eccentricity of inner pyrolyzing fuel as well as thermal conditions applied.

Simulation of Asymmetric Fuel Thermal Behavior Using 3D Gap Conductance Model (3 차원 간극 열전도도 모델을 이용한 핵연료봉의 열적 비대칭 거동 해석)

  • Kang, Chang Hak;Lee, Sung Uk;Yang, Dong Yol;Kim, Hyo Chan;Yang, Yong Sik
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.39 no.3
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    • pp.249-257
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    • 2015
  • A fuel assembly consists of fuel rods composed of pellets (UO2) and a cladding tube (Zircaloy). The role of the fuel rods in the reactor is to generate heat by nuclear fission, as well as to retain fission products during operation. A simulation method using a computer program was used to evaluate the safety of the nuclear fuel rods. This computer program has been called the fuel performance code. In the analysis of a light water reactor fuel rod, the gap conductance, which depended on the distance between the pellets and cladding tube, mainly influenced the thermomechanical behavior of the fuel rod. In this work, a 3D gap element was proposed to simulate the thermo-mechanical behavior of the nuclear fuel rod, considering the gap conductance. To implement the proposed 3D gap element, a 3D thermo-mechanical module was also developed using FORTRAN90. The asymmetric characteristics of the nuclear fuel rod, such as the MPS (missing pellet surface) and eccentricity, were simulated to evaluate the proposed 3D gap element.

Effects of Intake Port Swirl and Fuel Injection System on the Performance and Exhaust Emissions in a Turbocharged DI Diesel Engine (터보 차져 DI 디젤엔진에 있어서 성능 및 배기배출물에 미치는 흡기 포트 선회 유동 및 연료 분사계의 성능)

  • Yoon, Jun-Kyu;Cha, Kyung-Ok
    • Journal of ILASS-Korea
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    • v.10 no.3
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    • pp.45-53
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    • 2005
  • The purpose of this study is to analyze that intake port swirl and fuel injection system have an effect on the engine performance in a turbocharged D.I. diesel engine of the displacement 9.4L. As result of steady flow test, when the valve eccentricity ratio moved to cylinder wall, the flow coefficient and swirl intensity is increased. And as the swirl is increased, the mean flow coefficient is decreased, whereas the Gulf factor is increased. Through this engine test, it can be expected to meet performance and emissions by the following applied parameters; the swirl ratio is 2.43, injection timing is BTDC 13oCA and compression is 15.5.

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The Characteristic of Floating Ring Seal with Modified Geometry Configuration (기하학적 형상 변경에 따른 플로팅 링 실의 특성 연구)

  • Kim, Kyoung-Wook;Kim, Chang-Ho;Ha, Tae-Wong;Lee, Yong-Bok
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2006.05a
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    • pp.1142-1148
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    • 2006
  • The floating ring seal which is used in the high pressure turbo pump is frequently used in the oxidizer pump and the fuel pump of the turbo pump of the liquid propulsion rocket, because it is able to minimize clearance to decrease the leakage flow rate. But, floating ring seal has a tendency to increase the force which caused instability of system as the eccentricity ratio increases. In this paper, we devised design of floating ring seal which decrease contact area between floating and supporting ring. Modified floating ring seal has a tendency to decrease the eccentricity ratio compare with original floating ring seal. The whirl frequency ratio which is able to distinguish stability of system decrease compare with original floating ring seal

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A Study on the Flow Characteristics and Engine Performance with Swirl Ratio Variance of Intake Port (흡기포트 선회비 변경에 따른 유동특성 및 엔진성능에 관한 연구)

  • Yoon, Jun-Kyu;Cha, Kyung-Ok
    • Proceedings of the KSME Conference
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    • 2000.04b
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    • pp.899-905
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    • 2000
  • The characteristics of air flow and engine performance with swirl ratio variance of intake port In a turbocharged DI diesel engine was studied in this paper. The intake port flow is important factor which have influence on the engine performance and exhaust emission because the properties in the injected fuel depend on the combustion characteristics. The swirl ratio for ports was modified by hand-working and measured by impulse swirl meter. For the effects on performance and emission, the brake torque and brake specific fuel consumption were measured by engine dynamometer and NOx, smoke were measured by gas analyzer and smoke meter. As a result of steady flow test, when the valve eccentricity ratio are closed to cylinder wall, the flow coefficient and swirl intensity are increased. And as the swirl ratio is increased, the mean flow coefficient is decreasing, whereas the gulf factor is increasing. Also, through engine test its can be expected to meet performance and emission by optimizing the main parameters; the swirl ratio of intake port, injection timing and compression ratio.

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Effects of the Flow Characteristics of Helical Intake Port on the Performance and Emission in a Turbocharged DI Diesel Engine. (나선형 흡기포트의 유동특성이 과급식 디젤엔진의 성능 및 배출가스에 미치는 영향)

  • 윤준규;양진승;차경옥
    • Journal of Advanced Marine Engineering and Technology
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    • v.24 no.5
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    • pp.86-96
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    • 2000
  • This study is to consider that the helical intake port flow and fuel injection system have effects on the characteristics of engine performance and emissions in a turbocharged DI diesel engine of the displacement 9.4L. The swirl ratio for ports was modified by hand-working and measured by impulse torque swirl meter, For the effects on performance and emission, the brake torque, BSFC were measured by engine dynamometer and NOx, smoke were by gas analyzer and smoke meter. As a result of steady flow test, when the valve eccentricity ratio are closed to cylinder wall, the flow coefficient and swirl intensity are increased, And as the swirl is increased, the mean flow coefficient is decreasing, whereas the gulf factor is increasing. Also, through engine test its can be expected to meet performance and emission by the following applied parameter; the swirl ratio is 2.43, injection timing is BTDC $13^{\circ}$CA and compression is 15.5.

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A Study on the Characteristics of Intake Port Flow and Performance with Swirl Ratio Variance in a Turbocharged D.I. Diesel Engine (과급 디젤엔진에서 선회비 변경에 따른 흡기 포트유동 및 엔진성능 특성에 관한 연구)

  • Yoon, Jun-Kyu;Cha, Kyung-Ok
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.24 no.9
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    • pp.1185-1194
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    • 2000
  • The characteristics of intake port flow and engine performance with swirl ratio variance in a turbocharged D.I. diesel engine were studied in this paper. The intake port flow is important factor which have influence on the engine performance and exhaust emission because the properties in the injected fuel depend on the combustion characteristics. Through these experiments it can be expected to satisfy performance and emission by optimizing the main parameters; the swirl ratio of intake port, injection timing and compression ratio. The swirl ratio for ports was modified by hand-working and measured by impulse swirl meter. For the effects on performance and emission, the brake torque and brake specific fuel consumption were measured by engine dynamometer, NOx and smoke were measured by gas analyzer and smoke meter. The results of steady flow test are as follows; as the valve eccentricity ratio are closed to cylinder wall, the flow coefficient and swirl intensity are increased. Also we realized that there is a trade-off that the increase of swirl ratio decreases mean flow coefficient and increases the Gulf factor. And the optimum parameters to meet performance and emission through engine test are as follows; the swirl ratio 2.43, injection timing BTDC 13oCA and compression ratio 15.5.