The Experts below are selected from a list of 28413 Experts worldwide ranked by ideXlab platform
George Nakhla - One of the best experts on this subject based on the ideXlab platform.
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terminal settling velocity and drag coefficient of biofilm Coated Particles at high reynolds numbers
Aiche Journal, 2010Co-Authors: Mehran Andalib, George NakhlaAbstract:The drag force (Fd) on bio-Coated Particles taken from two laboratory-scale liquid–solid circulating fluidized bed bioreactors (LSCFBBR) was studied. The terminal velocities (ut) and Reynolds numbers (Ret) of Particles observed were higher than reported in the literature. Literature equations for determining ut were found inadequate to predict drag coefficient (Cd) in Ret > 130. A new equation for determining Fd as an explicit function of terminal settling velocity was generated based on Archimedes numbers (Ar) of the biofilm-Coated Particle. The proposed equation adequately predicted the terminal settling velocity of other literature data at lower Ret of less than 130, with an accuracy >85%. © 2010 American Institute of Chemical Engineers AIChE J, 2010
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Terminal settling velocity and drag coefficient of biofilm‐Coated Particles at high Reynolds numbers
AIChE Journal, 2010Co-Authors: Mehran Andalib, Jesse Zhu, George NakhlaAbstract:The drag force (Fd) on bio-Coated Particles taken from two laboratory-scale liquid–solid circulating fluidized bed bioreactors (LSCFBBR) was studied. The terminal velocities (ut) and Reynolds numbers (Ret) of Particles observed were higher than reported in the literature. Literature equations for determining ut were found inadequate to predict drag coefficient (Cd) in Ret > 130. A new equation for determining Fd as an explicit function of terminal settling velocity was generated based on Archimedes numbers (Ar) of the biofilm-Coated Particle. The proposed equation adequately predicted the terminal settling velocity of other literature data at lower Ret of less than 130, with an accuracy >85%. © 2010 American Institute of Chemical Engineers AIChE J, 2010
John T. Maki - One of the best experts on this subject based on the ideXlab platform.
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TRISO-Coated Particle Fuel Performance
Comprehensive Nuclear Materials, 2012Co-Authors: David A. Petti, Paul A. Demkowicz, John T. Maki, R.r. HobbinsAbstract:Tristructural isotropic (TRISO)-Coated Particle fuel is used in all current and planned high-temperature gas-cooled reactors (HTGRs). The robustness of this fuel, coupled with the high heat capacity of graphite, has led to the development of modular HTGRs with a high degree of passive safety. In this chapter, the irradiation and accident performance of modern TRISO-Coated Particle fuel around the world are reviewed. For all HTGRs, TRISO-Coated Particle fuel forms the heart of the concept. Such fuels have been studied extensively over the past four decades around the world, for example, in countries including the United Kingdom, Germany, Japan, the United States, Russia, China, and more recently, South Africa.
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the doe advanced gas reactor fuel development and qualification program
JOM, 2010Co-Authors: David A. Petti, John T. Maki, John D. Hunn, Peter J Pappano, Charles M Barnes, John Saurwein, Scott G Nagley, James Kendall, Richard R HobbinsAbstract:The high outlet temperatures and high thermal-energy conversion efficiency of modular high-temperature gas-cooled reactors (HTGRs) enable an efficient and cost-effective integration of the reactor system with non-electricity-generation applications, such as process heat and/or hydrogen production, for the many petrochemical and other industrial processes that require temperatures between 300°C and 900°C. The U.S. Department of Energy (DOE) has selected the HTGR concept for the Next Generation Nuclear Plant (NGNP) Project as a transformative application of nuclear energy that will demonstrate emissions-free nuclear-assisted electricity, process heat, and hydrogen production, thereby reducing greenhouse-gas emissions and enhancing energy security. The objective of the DOE Advanced Gas Reactor (AGR) Fuel Development and Qualification program is to qualify tristructural isotropic (TRISO)-Coated Particle fuel for use in HTGRs. An overview of the program and recent progress is presented.
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the doe advanced gas reactor fuel development and qualification program
JOM, 2010Co-Authors: D A Petti, John T. Maki, John D. Hunn, Peter J Pappano, Charles M Barnes, John Saurwein, Scott G Nagley, James Kendall, Richard R HobbinsAbstract:The high outlet temperatures and high thermal-energy conversion efficiency of modular high-temperature gas-cooled reactors (HTGRs) enable an efficient and cost-effective integration of the reactor system with non-electricity-generation applications, such as process heat and/or hydrogen production, for the many petrochemical and other industrial processes that require temperatures between 300°C and 900°C. The U.S. Department of Energy (DOE) has selected the HTGR concept for the Next Generation Nuclear Plant (NGNP) Project as a transformative application of nuclear energy that will demonstrate emissions-free nuclear-assisted electricity, process heat, and hydrogen production, thereby reducing greenhouse-gas emissions and enhancing energy security. The objective of the DOE Advanced Gas Reactor (AGR) Fuel Development and Qualification program is to qualify tristructural isotropic (TRISO)-Coated Particle fuel for use in HTGRs. An overview of the program and recent progress is presented.
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the challenges associated with high burnup high temperature and accelerated irradiation for triso Coated Particle fuel
Journal of Nuclear Materials, 2007Co-Authors: John T. Maki, David A. Petti, D L Knudson, Gregory K. MillerAbstract:Abstract Fuel service conditions proposed for the very high temperature reactor will be challenging. All major fuel-related design parameters (burnup, temperature, fast neutron fluence, power density, Particle packing fraction) exceed the values that were qualified in the successful German UO2 Coated Particle fuel development program in the 1980s. Of particular concern are the high burnup and high temperatures expected in the very high temperature reactor. In this paper, the challenges associated with high burnup and high temperature are evaluated quantitatively by examining the performance of the fuel in terms of different known failure mechanisms. Potential design solutions to ameliorate the negative effects of high burnup and high temperature are discussed. Also of concern are the effects of accelerated irradiation on Coated fuel that often occur during irradiation testing. These effects are evaluated in this paper and recommendations concerning allowable levels of accelerations are presented.
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The Challenges Associated with High Burnup and High Temperature for UO2 TRISO-Coated Particle Fuel
2005Co-Authors: David A. Petti, John T. MakiAbstract:The fuel service conditions for the DOE Next Generation Nuclear Plant (NGNP) will be challenging. All major fuel related design parameters (burnup, temperature, fast neutron fluence, power density, Particle packing fraction) exceed the values that were qualified in the successful German UO2 TRISO-Coated Particle fuel development program in the 1980s. While TRISO-Coated Particle fuel has been irradiated at NGNP relevant levels for two or three of the design parameters, no data exist for TRISO-Coated Particle fuel for all five parameters simultaneously. Of particular concern are the high burnup and high temperatures expected in the NGNP. In this paper, where possible, we evaluate the challenges associated with high burnup and high temperature quantitatively by examining the performance of the fuel in terms of different known failure mechanisms. Potential design solutions to ameliorate the negative effects of high burnup and high temperature are also discussed.
David A. Petti - One of the best experts on this subject based on the ideXlab platform.
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TRISO-Coated Particle Fuel Performance
Comprehensive Nuclear Materials, 2012Co-Authors: David A. Petti, Paul A. Demkowicz, John T. Maki, R.r. HobbinsAbstract:Tristructural isotropic (TRISO)-Coated Particle fuel is used in all current and planned high-temperature gas-cooled reactors (HTGRs). The robustness of this fuel, coupled with the high heat capacity of graphite, has led to the development of modular HTGRs with a high degree of passive safety. In this chapter, the irradiation and accident performance of modern TRISO-Coated Particle fuel around the world are reviewed. For all HTGRs, TRISO-Coated Particle fuel forms the heart of the concept. Such fuels have been studied extensively over the past four decades around the world, for example, in countries including the United Kingdom, Germany, Japan, the United States, Russia, China, and more recently, South Africa.
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the doe advanced gas reactor fuel development and qualification program
JOM, 2010Co-Authors: David A. Petti, John T. Maki, John D. Hunn, Peter J Pappano, Charles M Barnes, John Saurwein, Scott G Nagley, James Kendall, Richard R HobbinsAbstract:The high outlet temperatures and high thermal-energy conversion efficiency of modular high-temperature gas-cooled reactors (HTGRs) enable an efficient and cost-effective integration of the reactor system with non-electricity-generation applications, such as process heat and/or hydrogen production, for the many petrochemical and other industrial processes that require temperatures between 300°C and 900°C. The U.S. Department of Energy (DOE) has selected the HTGR concept for the Next Generation Nuclear Plant (NGNP) Project as a transformative application of nuclear energy that will demonstrate emissions-free nuclear-assisted electricity, process heat, and hydrogen production, thereby reducing greenhouse-gas emissions and enhancing energy security. The objective of the DOE Advanced Gas Reactor (AGR) Fuel Development and Qualification program is to qualify tristructural isotropic (TRISO)-Coated Particle fuel for use in HTGRs. An overview of the program and recent progress is presented.
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the challenges associated with high burnup high temperature and accelerated irradiation for triso Coated Particle fuel
Journal of Nuclear Materials, 2007Co-Authors: John T. Maki, David A. Petti, D L Knudson, Gregory K. MillerAbstract:Abstract Fuel service conditions proposed for the very high temperature reactor will be challenging. All major fuel-related design parameters (burnup, temperature, fast neutron fluence, power density, Particle packing fraction) exceed the values that were qualified in the successful German UO2 Coated Particle fuel development program in the 1980s. Of particular concern are the high burnup and high temperatures expected in the very high temperature reactor. In this paper, the challenges associated with high burnup and high temperature are evaluated quantitatively by examining the performance of the fuel in terms of different known failure mechanisms. Potential design solutions to ameliorate the negative effects of high burnup and high temperature are discussed. Also of concern are the effects of accelerated irradiation on Coated fuel that often occur during irradiation testing. These effects are evaluated in this paper and recommendations concerning allowable levels of accelerations are presented.
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The Challenges Associated with High Burnup and High Temperature for UO2 TRISO-Coated Particle Fuel
2005Co-Authors: David A. Petti, John T. MakiAbstract:The fuel service conditions for the DOE Next Generation Nuclear Plant (NGNP) will be challenging. All major fuel related design parameters (burnup, temperature, fast neutron fluence, power density, Particle packing fraction) exceed the values that were qualified in the successful German UO2 TRISO-Coated Particle fuel development program in the 1980s. While TRISO-Coated Particle fuel has been irradiated at NGNP relevant levels for two or three of the design parameters, no data exist for TRISO-Coated Particle fuel for all five parameters simultaneously. Of particular concern are the high burnup and high temperatures expected in the NGNP. In this paper, where possible, we evaluate the challenges associated with high burnup and high temperature quantitatively by examining the performance of the fuel in terms of different known failure mechanisms. Potential design solutions to ameliorate the negative effects of high burnup and high temperature are also discussed.
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Development of Improved Models and Designs for Coated-Particle Gas Reactor Fuels -- Final Report under the International Nuclear Energy Research Initiative (I-NERI)
2004Co-Authors: David A. Petti, Philippe Martin, Mayeul Phelip, Ronald G. BallingerAbstract:The objective of this INERI project was to develop improved fuel behavior models for gas reactor Coated-Particle fuels and to explore improved Coated-Particle fuel designs that could be used reliably at very high burnups and potentially in gas-cooled fast reactors. Project participants included the Idaho National Engineering Laboratory (INEEL), Centre Etude Atomique (CEA), and the Massachusetts Institute of Technology (MIT). To accomplish the project objectives, work was organized into five tasks.
Mehran Andalib - One of the best experts on this subject based on the ideXlab platform.
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terminal settling velocity and drag coefficient of biofilm Coated Particles at high reynolds numbers
Aiche Journal, 2010Co-Authors: Mehran Andalib, George NakhlaAbstract:The drag force (Fd) on bio-Coated Particles taken from two laboratory-scale liquid–solid circulating fluidized bed bioreactors (LSCFBBR) was studied. The terminal velocities (ut) and Reynolds numbers (Ret) of Particles observed were higher than reported in the literature. Literature equations for determining ut were found inadequate to predict drag coefficient (Cd) in Ret > 130. A new equation for determining Fd as an explicit function of terminal settling velocity was generated based on Archimedes numbers (Ar) of the biofilm-Coated Particle. The proposed equation adequately predicted the terminal settling velocity of other literature data at lower Ret of less than 130, with an accuracy >85%. © 2010 American Institute of Chemical Engineers AIChE J, 2010
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Terminal settling velocity and drag coefficient of biofilm‐Coated Particles at high Reynolds numbers
AIChE Journal, 2010Co-Authors: Mehran Andalib, Jesse Zhu, George NakhlaAbstract:The drag force (Fd) on bio-Coated Particles taken from two laboratory-scale liquid–solid circulating fluidized bed bioreactors (LSCFBBR) was studied. The terminal velocities (ut) and Reynolds numbers (Ret) of Particles observed were higher than reported in the literature. Literature equations for determining ut were found inadequate to predict drag coefficient (Cd) in Ret > 130. A new equation for determining Fd as an explicit function of terminal settling velocity was generated based on Archimedes numbers (Ar) of the biofilm-Coated Particle. The proposed equation adequately predicted the terminal settling velocity of other literature data at lower Ret of less than 130, with an accuracy >85%. © 2010 American Institute of Chemical Engineers AIChE J, 2010
Gregory K. Miller - One of the best experts on this subject based on the ideXlab platform.
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STRESS ANALYSIS OF Coated Particle FUEL IN GRAPHITE OF HIGH-TEMPERATURE REACTORS
Nuclear Technology, 2008Co-Authors: B. Boer, Abderrafi M. Ougouag, J.l. Kloosterman, Gregory K. MillerAbstract:The Particle STress Analysis (PASTA) code was written to evaluate stresses in Coated Particle fuel embedded in graphite of high-temperature reactors (HTRs). Existing models for predicting stresses in Coated Particle fuels were extended with a treatment of stresses induced by dimensional change of the matrix graphite and stresses caused by neighboring Particles. PASTA was applied to two practical cases in order to evaluate the significance of this model extension. Thermal hydraulics, neutronics, and fuel depletion calculation tools were used to calculate the fuel conditions in these cases. Stresses in the first fuel loading of the High-Temperature Engineering Test Reactor (HTTR) and in the fuel of a 400-MW(thermal) pebble bed reactor were analyzed. It is found that the presence of the matrix material plays a significant role in the determination of the stresses that apply to a single isolated TRISO Particle as well as in the transmittal of the stresses between Particles in actual pebble designs.
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the challenges associated with high burnup high temperature and accelerated irradiation for triso Coated Particle fuel
Journal of Nuclear Materials, 2007Co-Authors: John T. Maki, David A. Petti, D L Knudson, Gregory K. MillerAbstract:Abstract Fuel service conditions proposed for the very high temperature reactor will be challenging. All major fuel-related design parameters (burnup, temperature, fast neutron fluence, power density, Particle packing fraction) exceed the values that were qualified in the successful German UO2 Coated Particle fuel development program in the 1980s. Of particular concern are the high burnup and high temperatures expected in the very high temperature reactor. In this paper, the challenges associated with high burnup and high temperature are evaluated quantitatively by examining the performance of the fuel in terms of different known failure mechanisms. Potential design solutions to ameliorate the negative effects of high burnup and high temperature are discussed. Also of concern are the effects of accelerated irradiation on Coated fuel that often occur during irradiation testing. These effects are evaluated in this paper and recommendations concerning allowable levels of accelerations are presented.
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consideration of the effects of partial debonding of the ipyc and Particle asphericity on triso Coated fuel behavior
Journal of Nuclear Materials, 2004Co-Authors: Gregory K. Miller, David A. Petti, John T. MakiAbstract:The fundamental design for a gas-cooled reactor relies on the behavior of the Coated Particle fuel. The coating layers surrounding the fuel kernels in these spherical Particles, consisting of pyrolytic carbon and silicon carbide layers, act as a pressure vessel that retains fission product gases. Many more fuel Particles have failed in US irradiations than would be expected when only one-dimensional pressure vessel failures are considered. Post-irradiation examinations indicate that multi-dimensional effects may have contributed to these failures, such as (1) irradiation-induced shrinkage cracks in the inner pyrocarbon (IPyC) layer, (2) partial debonding between the IPyC and SiC layers, and (3) deviations from a perfectly spherical shape. An approach that was used previously to evaluate the effects of irradiation-induced shrinkage cracks is used herein to assess the effects of partial debonding and asphericity. Results of this investigation serve to identify circumstances where these mechanisms may contribute to Particle failures.
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key differences in the fabrication irradiation and high temperature accident testing of us and german triso Coated Particle fuel and their implications on fuel performance
Nuclear Engineering and Design, 2003Co-Authors: David A. Petti, John T. Maki, Richard R Hobbins, Jacopo Buongiorno, Gregory K. MillerAbstract:Historically, the irradiation performance of TRISO-Coated gas reactor Particle fuel in Germany has been superior to that in the US. German fuel generally has displayed gas release values during irradiation three orders of magnitude lower than US fuel. Thus, we have critically examined the TRISO-Coated fuel fabrication processes in the US and Germany and the associated irradiation database with a goal of understanding why the German fuel behaves acceptably, why the US fuel has not faired as well, and what process/production parameters impart the reliable performance to this fuel form. The postirradiation examination results are also reviewed to identify failure mechanisms that may be the cause of the poorer US irradiation performance. This comparison will help determine the roles that Particle fuel process/product attributes and irradiation conditions (burnup, fast neutron fluence, temperature, degree of acceleration) have on the behavior of the fuel during irradiation and provide a more quantitative linkage between acceptable processing parameters, as-fabricated fuel properties and subsequent in-reactor performance.
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statistical approach and benchmarking for modeling of multi dimensional behavior in triso Coated fuel Particles
Journal of Nuclear Materials, 2003Co-Authors: Gregory K. Miller, David A. Petti, Dominic J Varacalle, John T. MakiAbstract:The fundamental design for a gas-cooled reactor relies on the behavior of the Coated Particle fuel. The coating layers, termed the TRISO coating, act as a mini-pressure vessel that retains fission products. Results of US irradiation experiments show that many more fuel Particles have failed than can be attributed to one-dimensional pressure vessel failures alone. Post-irradiation examinations indicate that multi-dimensional effects, such as the presence of irradiation-induced shrinkage cracks in the inner pyrolytic carbon layer, contribute to these failures. To address these effects, the methods of prior one-dimensional models are expanded to capture the stress intensification associated with multi-dimensional behavior. An approximation of the stress levels enables the treatment of statistical variations in numerous design parameters and Monte Carlo sampling over a large number of Particles. The approach is shown to make reasonable predictions when used to calculate failure probabilities for irradiation experiments of the New Production – Modular High Temperature Gas Cooled Reactor Program.