The Experts below are selected from a list of 2196 Experts worldwide ranked by ideXlab platform
Haci Mehmet şahin - One of the best experts on this subject based on the ideXlab platform.
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investigation of a gas turbine modular helium reactor using reactor Grade Plutonium with 232th and 238u
Progress in Nuclear Energy, 2016Co-Authors: Sumer şahin, Ozgur Erol, Haci Mehmet şahinAbstract:Abstract Utilization of natural uranium (nat-U) and thorium as fertile fuels has been investigated by in a Gas Turbine – Modular Helium Reactor (GTMHR) using reactor Grade Plutonium as driver fuel. A neutronic analysis for the full core reactor was performed by using MCNP5 with ENDF/B-VI cross-section library. Different mixture ratios were tested in order to find the appropriate mixture ratio of fertile and fissile fuel particles that gives a comparable k eff value of the reference uranium fuel. Time dependent calculations were performed by using MONTEBURN2.0 with ORIGEN2.2 for each selected mixture. Different parameters (operation time, burnup value, fissile isotope change, etc.) were subject of performance comparison. The operation time and burnup values were close to each other with nat-U and thorium, namely 3205 days and 176 GWd/MTU for the former and 3175 days 181 GWd/MTU for the latter fertile fuel. In addition, the fissile isotope amount changed from initially 6940.1 kg–4579.2 kg at the end of its operation time for nat-U. These values were obtained for thorium as 6603.3 kg–4250.2 kg, respectively.
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weapons Grade Plutonium utilization with fertile materials in a gas turbine modular helium reactor
Annals of Nuclear Energy, 2015Co-Authors: Ozgur Erol, Haci Mehmet şahinAbstract:Abstract In this study, neutronic performances of the fertile thorium and natural uranium were studied in a Gas Turbine-Modular Helium Reactor using Weapons Grade Plutonium as fissile fuel. In the first step of the calculation procedure, a series of neutronic calculations were made in order to find the proper mixture ratios for these fertile fuel mixtures by using MCNP5 with ENDF/B-VI cross-section library. After the determination of these mixture ratios, in order to compare these fuel mixtures, time dependent neutronic calculations were made by using Monteburns 2.0 with MCNP5 and Origen 2.2. According to the results obtained, different parameters (operation time, burnup value, fissile isotope production, etc.) were compared. Results of the first step showed that, in order to reach the reference k eff value, 690.6 kg more fissile isotope was used in natural uranium mixture than the thorium mixture. In the second step of this study, time dependent calculations showed that for the natural uranium mixture, operation time and burnup values were found as 1935 days and 177.76 GWd/MTU, respectively, while these values for thorium mixture were 1925 days and 153.95 GWd/MTU.
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Utilization of thorium in a Gas Turbine – Modular Helium Reactor
Energy Conversion and Management, 2012Co-Authors: Haci Mehmet şahin, Ozgur Erol, Adem AcirAbstract:Abstract Gas Turbine-Modular Helium Reactor (GT-MHR) is one of the new types of the reactors with high efficiency and increased safety features. The usage of different kinds of fissile material in this reactor can increase the life of it. Weapons-Grade Plutonium (WGrPu), which can be acquired from the old dismantled nuclear weapons, can be an option in a GT-MHR. In order to increase the sustainability of the WGrPu resources this fuel can be mixed with thorium, which is a fertile material that can be found in the nature and has resources three times more than uranium. In this study, possibility of utilization of the weapons-Grade Plutonium–thorium mixture was investigated and an optimum mixture ratio was determined. The behavior of this mixture and the original fuel was studied by using MCNP5 1.4, Monteburns 2.0 and Origen 2.2 tools. Calculations showed that, a GT-MHR type reactor, which is using the original TRISO fuel particle mixture of 20% enriched uranium + natural uranium (original fuel) has an effective multiplication factor (keff) of 1.270. Corresponding to this keff value the weapons Grade Plutonium/thorium oxide mixture was found 19%/81%. By using Monteburns Code, the operation time, which describes the time passed until the reactor reaches a keff value of 1.02, was found as 515 days for the original fuel and 1175 days for the weapons Grade Plutonium mixture. Furthermore, the burn-up values for the original fuel and WGrPu fuels were found as 47.69 and 119.27 GWd/MTU, respectively.
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utilization of triso fuel with reactor Grade Plutonium in candu reactors
Nuclear Engineering and Design, 2010Co-Authors: Sumer şahin, Haci Mehmet şahin, Adem AcirAbstract:Abstract Large quantities of Plutonium have been accumulated in the nuclear waste of civilian LWRs and CANDU reactors. Reactor Grade Plutonium and heavy water moderator can give a good combination with respect to neutron economy. On the other hand, TRISO type fuel can withstand very high fuel burn-up levels. The paper investigates the prospects of utilization of TRISO fuel made of reactor Grade Plutonium in CANDU reactors. TRISO fuels particles are imbedded body-centered cubic (BCC) in a graphite matrix with a volume fraction of 68%. The fuel compacts conform to the dimensions of CANDU fuel compacts are inserted in rods with zircolay cladding. In the first phase of investigations, five new mixed fuel have been selected for CANDU reactors composed of 4% RG-PuO 2 + 96% ThO 2 ; 6% RG-PuO 2 + 94% ThO 2 ; 10% RG-PuO 2 + 90% ThO 2 ; 20% RG-PuO 2 + 80% ThO 2 ; 30% RG-PuO 2 + 70% ThO 2 . Initial reactor criticality ( k ∞,0 values) for the modes , , , and are calculated as 1.4294, 1.5035, 1.5678, 1.6249, and 1.6535, respectively. Corresponding operation lifetimes are ∼0.65, 1.1, 1.9, 3.5, and 4.8 years and with burn ups of ∼30 000, 60 000, 100 000, 200 000 and 290 000 MW d/tonne, respectively. The higher initial Plutonium charge is the higher burn ups can be achieved. In the second phase, a graphical-numerical power flattening procedure has been applied with radially variable mixed fuel composition in the fuel bundle. Mixed fuel fractions leading to quasi-constant power production are found in the 1st, 2nd, 3rd and 4th row to be as 100% PuO 2 , 80/20% PuO 2 /ThO 2 , 60/40% PuO 2 /ThO 2 , and 40/60% PuO 2 /ThO 2 , respectively. Higher Plutonium amount in the flattened case increases reactor operation lifetime to >8 years and the burn up to 580 000 MW d/tonne. Power flattening in the bundle leads to higher power plant factor and quasi-uniform fuel utilization, reduces thermal and material stresses, and avoids local thermal peaks. Extended burn-up Grade implies drastic reduction of the nuclear waste material per unit energy output for final waste disposal.
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Criticality investigations for the fixed bed nuclear reactor using thorium fuel mixed with Plutonium or minor actinides
Annals of Nuclear Energy, 2009Co-Authors: Sumer şahin, Haci Mehmet şahin, Adem Acir, Tawfik A. Al-kusayerAbstract:Prospective fuels for a new reactor type, the so called fixed bed nuclear reactor (FBNR) are investigated with respect to reactor criticality. These are r low enriched uranium (LEU); s weapon Grade Plutonium + ThO2; t reactor Grade Plutonium + ThO2; and u minor actinides in the spent fuel of light water reactors (LWRs) + ThO2. Reactor Grade Plutonium and minor actinides are considered as highly radioactive and radio-toxic nuclear waste products so that one can expect that they will have negative fuel costs. The criticality calculations are conducted with SCALE5.1 using S8–P3 approximation in 238 neutron energy groups with 90 groups in thermal energy region. The study has shown that the reactor criticality has lower values with uranium fuel and increases passing to minor actinides, reactor Grade Plutonium and weapon Grade Plutonium. Using LEU, an enrichment Grade of 9% has resulted with keff = 1.2744. Mixed fuel with weapon Grade Plutonium made of 20% PuO2 + 80% ThO2 yields keff = 1.2864. Whereas a mixed fuel with reactor Grade Plutonium made of 35% PuO2 + 65% ThO2 brings it to keff = 1.267. Even the very hazardous nuclear waste of LWRs, namely minor actinides turn out to be high quality nuclear fuel due to the excellent neutron economy of FBNR. A relatively high reactor criticality of keff = 1.2673 is achieved by 50% MAO2 + 50% ThO2.
Adem Acir - One of the best experts on this subject based on the ideXlab platform.
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Utilization of thorium in a Gas Turbine – Modular Helium Reactor
Energy Conversion and Management, 2012Co-Authors: Haci Mehmet şahin, Ozgur Erol, Adem AcirAbstract:Abstract Gas Turbine-Modular Helium Reactor (GT-MHR) is one of the new types of the reactors with high efficiency and increased safety features. The usage of different kinds of fissile material in this reactor can increase the life of it. Weapons-Grade Plutonium (WGrPu), which can be acquired from the old dismantled nuclear weapons, can be an option in a GT-MHR. In order to increase the sustainability of the WGrPu resources this fuel can be mixed with thorium, which is a fertile material that can be found in the nature and has resources three times more than uranium. In this study, possibility of utilization of the weapons-Grade Plutonium–thorium mixture was investigated and an optimum mixture ratio was determined. The behavior of this mixture and the original fuel was studied by using MCNP5 1.4, Monteburns 2.0 and Origen 2.2 tools. Calculations showed that, a GT-MHR type reactor, which is using the original TRISO fuel particle mixture of 20% enriched uranium + natural uranium (original fuel) has an effective multiplication factor (keff) of 1.270. Corresponding to this keff value the weapons Grade Plutonium/thorium oxide mixture was found 19%/81%. By using Monteburns Code, the operation time, which describes the time passed until the reactor reaches a keff value of 1.02, was found as 515 days for the original fuel and 1175 days for the weapons Grade Plutonium mixture. Furthermore, the burn-up values for the original fuel and WGrPu fuels were found as 47.69 and 119.27 GWd/MTU, respectively.
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Neutronic analysis of the PBMR-400 full core using thorium fuel mixed with Plutonium or minor actinides
Annals of Nuclear Energy, 2012Co-Authors: Adem Acir, H CoskunAbstract:Abstract Time evolution of criticality and burnup Grades of the PBMR were investigated for reactor Grade Plutonium and minor actinides in the spent fuel of light water reactors (LWRs) mixed with thoria. The calculations were performed by employing the computer codes MCNP and MONTEBURNS 2.0 and using the ENDF/B-V nuclear data library. Firstly, the Plutonium–thorium and minor actinides–thorium ratio was determined by using the initial keff value of the original uranium fuel design. After the selection of the Plutonium/minor actinides–thorium mixture ratio, the time-dependent neutronic behavior of the reactor Grade Plutonium and minor actinides and original fuels in a PBMR-400 reactor was calculated by using the MCNP code. Finally, keff, burnup and operation time values of the fuels were compared. The core effective multiplication factor (keff) for the original fuel which has 9.6 wt.% enriched uranium was computed as 1.2395. Corresponding to this keff value the reactor Grade Plutonium/thorium and minor actinide/thorium oxide mixtures were found to be 30%/70% and 50%/50%, respectively. The core lives for the original, the reactor Grade Plutonium/thorium and the minor actinide/thorium fuels were calculated as ∼3.2, ∼6.5 and ∼5.5 years, whereas, the corresponding burnups came out to be 99,000, ∼190,000 and ∼166,000 MWD/T, respectively, for an end of life keff set equal to 1.02.
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utilization of triso fuel with reactor Grade Plutonium in candu reactors
Nuclear Engineering and Design, 2010Co-Authors: Sumer şahin, Haci Mehmet şahin, Adem AcirAbstract:Abstract Large quantities of Plutonium have been accumulated in the nuclear waste of civilian LWRs and CANDU reactors. Reactor Grade Plutonium and heavy water moderator can give a good combination with respect to neutron economy. On the other hand, TRISO type fuel can withstand very high fuel burn-up levels. The paper investigates the prospects of utilization of TRISO fuel made of reactor Grade Plutonium in CANDU reactors. TRISO fuels particles are imbedded body-centered cubic (BCC) in a graphite matrix with a volume fraction of 68%. The fuel compacts conform to the dimensions of CANDU fuel compacts are inserted in rods with zircolay cladding. In the first phase of investigations, five new mixed fuel have been selected for CANDU reactors composed of 4% RG-PuO 2 + 96% ThO 2 ; 6% RG-PuO 2 + 94% ThO 2 ; 10% RG-PuO 2 + 90% ThO 2 ; 20% RG-PuO 2 + 80% ThO 2 ; 30% RG-PuO 2 + 70% ThO 2 . Initial reactor criticality ( k ∞,0 values) for the modes , , , and are calculated as 1.4294, 1.5035, 1.5678, 1.6249, and 1.6535, respectively. Corresponding operation lifetimes are ∼0.65, 1.1, 1.9, 3.5, and 4.8 years and with burn ups of ∼30 000, 60 000, 100 000, 200 000 and 290 000 MW d/tonne, respectively. The higher initial Plutonium charge is the higher burn ups can be achieved. In the second phase, a graphical-numerical power flattening procedure has been applied with radially variable mixed fuel composition in the fuel bundle. Mixed fuel fractions leading to quasi-constant power production are found in the 1st, 2nd, 3rd and 4th row to be as 100% PuO 2 , 80/20% PuO 2 /ThO 2 , 60/40% PuO 2 /ThO 2 , and 40/60% PuO 2 /ThO 2 , respectively. Higher Plutonium amount in the flattened case increases reactor operation lifetime to >8 years and the burn up to 580 000 MW d/tonne. Power flattening in the bundle leads to higher power plant factor and quasi-uniform fuel utilization, reduces thermal and material stresses, and avoids local thermal peaks. Extended burn-up Grade implies drastic reduction of the nuclear waste material per unit energy output for final waste disposal.
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Criticality investigations for the fixed bed nuclear reactor using thorium fuel mixed with Plutonium or minor actinides
Annals of Nuclear Energy, 2009Co-Authors: Sumer şahin, Haci Mehmet şahin, Adem Acir, Tawfik A. Al-kusayerAbstract:Prospective fuels for a new reactor type, the so called fixed bed nuclear reactor (FBNR) are investigated with respect to reactor criticality. These are r low enriched uranium (LEU); s weapon Grade Plutonium + ThO2; t reactor Grade Plutonium + ThO2; and u minor actinides in the spent fuel of light water reactors (LWRs) + ThO2. Reactor Grade Plutonium and minor actinides are considered as highly radioactive and radio-toxic nuclear waste products so that one can expect that they will have negative fuel costs. The criticality calculations are conducted with SCALE5.1 using S8–P3 approximation in 238 neutron energy groups with 90 groups in thermal energy region. The study has shown that the reactor criticality has lower values with uranium fuel and increases passing to minor actinides, reactor Grade Plutonium and weapon Grade Plutonium. Using LEU, an enrichment Grade of 9% has resulted with keff = 1.2744. Mixed fuel with weapon Grade Plutonium made of 20% PuO2 + 80% ThO2 yields keff = 1.2864. Whereas a mixed fuel with reactor Grade Plutonium made of 35% PuO2 + 65% ThO2 brings it to keff = 1.267. Even the very hazardous nuclear waste of LWRs, namely minor actinides turn out to be high quality nuclear fuel due to the excellent neutron economy of FBNR. A relatively high reactor criticality of keff = 1.2673 is achieved by 50% MAO2 + 50% ThO2.
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increased fuel burn up in a candu thorium reactor using weapon Grade Plutonium
Nuclear Engineering and Design, 2006Co-Authors: Sumer şahin, Haci Mehmet şahin, Kadir Yildiz, Necmettin şahin, Adem AcirAbstract:Abstract Weapon Grade Plutonium is used as a booster fissile fuel material in the form of mixed ThO 2 /PuO 2 fuel in a Canada Deuterium Uranium (CANDU) fuel bundle in order to assure the initial criticality at startup. Two different fuel compositions have been used: (1) 97% thoria (ThO 2 ) + 3%PuO 2 and (2) 92% ThO 2 + 5% UO 2 + 3% PuO 2 . The latter is used to denaturize the new 233 U fuel with 238 U. The temporal variation of the criticality k ∞ and the burn-up values of the reactor have been calculated by full power operation for a period of 20 years. The criticality starts by k ∞ = ∼1.48 for both fuel compositions. A sharp decrease of the criticality has been observed in the first year as a consequence of rapid Plutonium burnout. The criticality becomes quasi constant after the second year and remains above k ∞ > 1.06 for ∼20 years. After the second year, the CANDU reactor begins to operate practically as a thorium burner. Very high burn up could be achieved with the same fuel material (up to 500,000 MW·D/T), provided that the fuel rod claddings would be replaced periodically (after every 50,000 or 100,000 MW·D/T). The reactor criticality will be sufficient until a great fraction of the thorium fuel is burnt up. This would reduce fuel fabrication costs and nuclear waste mass for final disposal per unit energy drastically.
A Caro - One of the best experts on this subject based on the ideXlab platform.
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triso particle and beryllium pebble thermo mechanical response in a fusion fission engine for incineration of weapons Grade Plutonium
ASME 2010 Pressure Vessels and Piping Conference: Volume 6 Parts A and B, 2010Co-Authors: M Caro, P Demange, J Marian, A CaroAbstract:Among the laser inertial fusion-fission energy (LIFE) engine concepts being considered at Lawrence Livermore National Laboratory (LLNL), weapons-Grade Plutonium (WGPu) LIFE is of particular interest because it is designed to burn excess WGPu material and achieve over 99% fraction of initial metal atoms (FIMAs). At the center of the LIFE concept lies a point source of 14MeV neutrons produced by inertial-confinement fusion (ICF) which drives a sub-critical fuel blanket located behind a neutron multiplier. Current design envisions tristructural isotropic (TRISO) particles embedded in a graphite matrix as fuel and Be as multiplier, both in pebble bed form and flowing in Flibe molten salt coolant. In previous work, neutron lifetime modeling and design of Be pebbles was discussed [10]. Constitutive equations were derived and a design criteria were developed for spherical Be pebbles on the basis of their thermo-mechanical behaviour under continued neutron exposure in the neutron multiplier for the LIFE engine. Utilizing the available material property data, Be pebbles lifetime could be estimated to be a minimum of 6 years. Here, we investigate the thermo-mechanical response of TRISO particles used for incineration of WUPu under LIFE operating conditions of high temperature and high neutron fast fluence. To this purpose, we make use of the thermo-mechanical fuel performance code HUPPCO, which is currently under development. The model accounts for spatial and time dependence of the material elastic properties, temperature, and irradiation swelling and creep mechanisms. Preliminary results show that the lifetime of WGPu TRISO particles is affected by changes in the fuel materials properties in time. At high fuel burnup, retention of fission products relies on the SiC containment boundary behavior as a minute pressure vessel. The discussion underlines the need to develop high-fidelity models of the performance of these new fuel designs, especially in the absence of a fast neutron source to test these fuels under relevant conditions.© 2010 ASME
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TRISO Particle and Beryllium Pebble Thermo-Mechanical Response in a Fusion/Fission Engine for Incineration of Weapons Grade Plutonium
ASME 2010 Pressure Vessels and Piping Conference: Volume 6 Parts A and B, 2010Co-Authors: M Caro, P Demange, J Marian, A CaroAbstract:Among the laser inertial fusion-fission energy (LIFE) engine concepts being considered at Lawrence Livermore National Laboratory (LLNL), weapons-Grade Plutonium (WGPu) LIFE is of particular interest because it is designed to burn excess WGPu material and achieve over 99% fraction of initial metal atoms (FIMAs). At the center of the LIFE concept lies a point source of 14MeV neutrons produced by inertial-confinement fusion (ICF) which drives a sub-critical fuel blanket located behind a neutron multiplier. Current design envisions tristructural isotropic (TRISO) particles embedded in a graphite matrix as fuel and Be as multiplier, both in pebble bed form and flowing in Flibe molten salt coolant. In previous work, neutron lifetime modeling and design of Be pebbles was discussed [10]. Constitutive equations were derived and a design criteria were developed for spherical Be pebbles on the basis of their thermo-mechanical behaviour under continued neutron exposure in the neutron multiplier for the LIFE engine. Utilizing the available material property data, Be pebbles lifetime could be estimated to be a minimum of 6 years. Here, we investigate the thermo-mechanical response of TRISO particles used for incineration of WUPu under LIFE operating conditions of high temperature and high neutron fast fluence. To this purpose, we make use of the thermo-mechanical fuel performance code HUPPCO, which is currently under development. The model accounts for spatial and time dependence of the material elastic properties, temperature, and irradiation swelling and creep mechanisms. Preliminary results show that the lifetime of WGPu TRISO particles is affected by changes in the fuel materials properties in time. At high fuel burnup, retention of fission products relies on the SiC containment boundary behavior as a minute pressure vessel. The discussion underlines the need to develop high-fidelity models of the performance of these new fuel designs, especially in the absence of a fast neutron source to test these fuels under relevant conditions.© 2010 ASME
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thermo mechanical response of a triso fuel particle in a fusion fission engine for incineration of weapons Grade Plutonium
Presented at: TMS 2010 Seattle WA United States Feb 14 - Feb 18 2010, 2009Co-Authors: M Caro, P Demange, J Marian, A CaroAbstract:The Laser Inertial Fusion-based (LIFE) engine is an advanced energy concept under development at Lawrence Livermore National Laboratory (LLNL). LIFE engine could be used to drive a subcritical fission blanket with fertile or fissile fuel. Current LIFE engine designs envisages fuel in pebble bed form with TRISO (tristructural isotropic) particles embedded in a graphite matrix, and pebbles flowing in molten salt Flibe (2LiF+BeF{sub 2}) coolant at T {approx} 700C. Weapons-Grade Plutonium (WGPu) fuel is an attractive option for LIFE engine involving the achievement of high fractional burnups in a short lifetime frame. However, WGPu LIFE engine operating conditions of high neutron fast fluence, high radiation damage, and high Helium and Hydrogen production pose severe challenges for typical TRISO particles. The thermo-mechanical fuel performance code HUPPCO (High burn-Up fuel Pebble Performance COde) currently under development accounts for spatial and time dependence of the material elastic properties, temperature, and irradiation swelling and creep mechanisms. In this work, some aspects of the thermo-mechanical response of TRISO particles used for incineration of weapons Grade fuel in LIFE engine are analyzed. Preliminary results show the importance of developing reliable high-fidelity models of the performance of these new fuel designs and the need of new experimental data relevant to WGPu LIFE conditions.
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Thermo-Mechanical Response of a TRISO Fuel Particle in a Fusion/Fission Engine for Incineration of Weapons Grade Plutonium
2009Co-Authors: M Caro, P Demange, J Marian, A CaroAbstract:The Laser Inertial Fusion-based (LIFE) engine is an advanced energy concept under development at Lawrence Livermore National Laboratory (LLNL). LIFE engine could be used to drive a subcritical fission blanket with fertile or fissile fuel. Current LIFE engine designs envisages fuel in pebble bed form with TRISO (tristructural isotropic) particles embedded in a graphite matrix, and pebbles flowing in molten salt Flibe (2LiF+BeF{sub 2}) coolant at T {approx} 700C. Weapons-Grade Plutonium (WGPu) fuel is an attractive option for LIFE engine involving the achievement of high fractional burnups in a short lifetime frame. However, WGPu LIFE engine operating conditions of high neutron fast fluence, high radiation damage, and high Helium and Hydrogen production pose severe challenges for typical TRISO particles. The thermo-mechanical fuel performance code HUPPCO (High burn-Up fuel Pebble Performance COde) currently under development accounts for spatial and time dependence of the material elastic properties, temperature, and irradiation swelling and creep mechanisms. In this work, some aspects of the thermo-mechanical response of TRISO particles used for incineration of weapons Grade fuel in LIFE engine are analyzed. Preliminary results show the importance of developing reliable high-fidelity models of the performance of these new fuel designs and the need of new experimental data relevant to WGPu LIFE conditions.
John C Butler - One of the best experts on this subject based on the ideXlab platform.
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a multiattribute utility analysis of alternatives for the disposition of surplus weapons Grade Plutonium
Operations Research, 1998Co-Authors: James S Dyer, Thomas A Edmunds, John C ButlerAbstract:This paper describes an application of multiattribute utility theory to support the selection of a technology for the disposition of surplus weapons-Grade Plutonium by the Department of Energy (DOE). This analysis evaluated 13 alternatives, examined the sensitivity of the recommendations to the weights and assumptions, and quantified the potential benefit of the simultaneous deployment of several technologies. The measures of performance that were identified through the creation of a hierarchy of objectives helped to organize the information collected during the evaluation process, and the results of the analysis were presented to DOE on several occasions. This analysis supported the final DOE recommendation to pursue a strategy of the parallel development of two of the most preferred technologies.
Sumer şahin - One of the best experts on this subject based on the ideXlab platform.
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investigation of a gas turbine modular helium reactor using reactor Grade Plutonium with 232th and 238u
Progress in Nuclear Energy, 2016Co-Authors: Sumer şahin, Ozgur Erol, Haci Mehmet şahinAbstract:Abstract Utilization of natural uranium (nat-U) and thorium as fertile fuels has been investigated by in a Gas Turbine – Modular Helium Reactor (GTMHR) using reactor Grade Plutonium as driver fuel. A neutronic analysis for the full core reactor was performed by using MCNP5 with ENDF/B-VI cross-section library. Different mixture ratios were tested in order to find the appropriate mixture ratio of fertile and fissile fuel particles that gives a comparable k eff value of the reference uranium fuel. Time dependent calculations were performed by using MONTEBURN2.0 with ORIGEN2.2 for each selected mixture. Different parameters (operation time, burnup value, fissile isotope change, etc.) were subject of performance comparison. The operation time and burnup values were close to each other with nat-U and thorium, namely 3205 days and 176 GWd/MTU for the former and 3175 days 181 GWd/MTU for the latter fertile fuel. In addition, the fissile isotope amount changed from initially 6940.1 kg–4579.2 kg at the end of its operation time for nat-U. These values were obtained for thorium as 6603.3 kg–4250.2 kg, respectively.
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utilization of triso fuel with reactor Grade Plutonium in candu reactors
Nuclear Engineering and Design, 2010Co-Authors: Sumer şahin, Haci Mehmet şahin, Adem AcirAbstract:Abstract Large quantities of Plutonium have been accumulated in the nuclear waste of civilian LWRs and CANDU reactors. Reactor Grade Plutonium and heavy water moderator can give a good combination with respect to neutron economy. On the other hand, TRISO type fuel can withstand very high fuel burn-up levels. The paper investigates the prospects of utilization of TRISO fuel made of reactor Grade Plutonium in CANDU reactors. TRISO fuels particles are imbedded body-centered cubic (BCC) in a graphite matrix with a volume fraction of 68%. The fuel compacts conform to the dimensions of CANDU fuel compacts are inserted in rods with zircolay cladding. In the first phase of investigations, five new mixed fuel have been selected for CANDU reactors composed of 4% RG-PuO 2 + 96% ThO 2 ; 6% RG-PuO 2 + 94% ThO 2 ; 10% RG-PuO 2 + 90% ThO 2 ; 20% RG-PuO 2 + 80% ThO 2 ; 30% RG-PuO 2 + 70% ThO 2 . Initial reactor criticality ( k ∞,0 values) for the modes , , , and are calculated as 1.4294, 1.5035, 1.5678, 1.6249, and 1.6535, respectively. Corresponding operation lifetimes are ∼0.65, 1.1, 1.9, 3.5, and 4.8 years and with burn ups of ∼30 000, 60 000, 100 000, 200 000 and 290 000 MW d/tonne, respectively. The higher initial Plutonium charge is the higher burn ups can be achieved. In the second phase, a graphical-numerical power flattening procedure has been applied with radially variable mixed fuel composition in the fuel bundle. Mixed fuel fractions leading to quasi-constant power production are found in the 1st, 2nd, 3rd and 4th row to be as 100% PuO 2 , 80/20% PuO 2 /ThO 2 , 60/40% PuO 2 /ThO 2 , and 40/60% PuO 2 /ThO 2 , respectively. Higher Plutonium amount in the flattened case increases reactor operation lifetime to >8 years and the burn up to 580 000 MW d/tonne. Power flattening in the bundle leads to higher power plant factor and quasi-uniform fuel utilization, reduces thermal and material stresses, and avoids local thermal peaks. Extended burn-up Grade implies drastic reduction of the nuclear waste material per unit energy output for final waste disposal.
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Criticality investigations for the fixed bed nuclear reactor using thorium fuel mixed with Plutonium or minor actinides
Annals of Nuclear Energy, 2009Co-Authors: Sumer şahin, Haci Mehmet şahin, Adem Acir, Tawfik A. Al-kusayerAbstract:Prospective fuels for a new reactor type, the so called fixed bed nuclear reactor (FBNR) are investigated with respect to reactor criticality. These are r low enriched uranium (LEU); s weapon Grade Plutonium + ThO2; t reactor Grade Plutonium + ThO2; and u minor actinides in the spent fuel of light water reactors (LWRs) + ThO2. Reactor Grade Plutonium and minor actinides are considered as highly radioactive and radio-toxic nuclear waste products so that one can expect that they will have negative fuel costs. The criticality calculations are conducted with SCALE5.1 using S8–P3 approximation in 238 neutron energy groups with 90 groups in thermal energy region. The study has shown that the reactor criticality has lower values with uranium fuel and increases passing to minor actinides, reactor Grade Plutonium and weapon Grade Plutonium. Using LEU, an enrichment Grade of 9% has resulted with keff = 1.2744. Mixed fuel with weapon Grade Plutonium made of 20% PuO2 + 80% ThO2 yields keff = 1.2864. Whereas a mixed fuel with reactor Grade Plutonium made of 35% PuO2 + 65% ThO2 brings it to keff = 1.267. Even the very hazardous nuclear waste of LWRs, namely minor actinides turn out to be high quality nuclear fuel due to the excellent neutron economy of FBNR. A relatively high reactor criticality of keff = 1.2673 is achieved by 50% MAO2 + 50% ThO2.
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increased fuel burn up in a candu thorium reactor using weapon Grade Plutonium
Nuclear Engineering and Design, 2006Co-Authors: Sumer şahin, Haci Mehmet şahin, Kadir Yildiz, Necmettin şahin, Adem AcirAbstract:Abstract Weapon Grade Plutonium is used as a booster fissile fuel material in the form of mixed ThO 2 /PuO 2 fuel in a Canada Deuterium Uranium (CANDU) fuel bundle in order to assure the initial criticality at startup. Two different fuel compositions have been used: (1) 97% thoria (ThO 2 ) + 3%PuO 2 and (2) 92% ThO 2 + 5% UO 2 + 3% PuO 2 . The latter is used to denaturize the new 233 U fuel with 238 U. The temporal variation of the criticality k ∞ and the burn-up values of the reactor have been calculated by full power operation for a period of 20 years. The criticality starts by k ∞ = ∼1.48 for both fuel compositions. A sharp decrease of the criticality has been observed in the first year as a consequence of rapid Plutonium burnout. The criticality becomes quasi constant after the second year and remains above k ∞ > 1.06 for ∼20 years. After the second year, the CANDU reactor begins to operate practically as a thorium burner. Very high burn up could be achieved with the same fuel material (up to 500,000 MW·D/T), provided that the fuel rod claddings would be replaced periodically (after every 50,000 or 100,000 MW·D/T). The reactor criticality will be sufficient until a great fraction of the thorium fuel is burnt up. This would reduce fuel fabrication costs and nuclear waste mass for final disposal per unit energy drastically.
