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Article Citation - WoS: 6Citation - Scopus: 15Investigation of a Gas Turbine-Modular Helium Reactor Using Reactor Grade Plutonium With 232th and 238u(Pergamon-elsevier Science Ltd, 2016) Sahin, Sumer; Erol, Ozgur; Sahin, Haci MehmetUtilization 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. (C) 2016 Elsevier Ltd. All rights reserved.Conference Object Citation - WoS: 34Citation - Scopus: 40Criticality and burn up evolutions of the Fixed Bed Nuclear Reactor with alternative fuels(Pergamon-elsevier Science Ltd, 2010) Sahin, Suemer; Sahin, Haci Mehmet; Acir, AdemTime evolution of criticality and burn-up grades of the Fixed Bed Nuclear Reactor (FBNR) are investigated for alternative fuels. These are: (1) low enriched uranium, (2) weapon grade plutonium, (3) reactor grade plutonium, and (4) minor actinides in the spent fuel of light water reactors (LWRs). The criticality calculations are conducted with SCALE 5.1 using S(8)-P(3) approximation in 238 neutron energy groups with 90 groups in thermal energy region. The main results of the study can be summarized as follows: (1) Low enriched uranium (UO(2)): FBNR with an enrichment grade of 9% and 19% will start with k(eff) = 1.2744 and k(eff) = 1.36 and can operate similar to 8 and >15 years with the same fuel charge, where criticality drops to k(eff) = 1.06 and a burn-up grade of 54 000 and >110000 MW.D/t can be attained. (2) Weapon grade plutonium: Such a high quality nuclear fuel suggests to be mixed with thorium. Second series of criticality calculations are conducted with fuel compositions made of thoria (ThO(2)) and weapon grade PuO(2), where PuO(2) component has been varied from 1% to 100%. Criticality with k(eff) > 1.0 is achieved by similar to 2.5% PuO(2). At 4% PuO(2), the reactor criticality will become satisfactory (k(eff) = 1.1121), rapidly increasing with more PuO(2). A reasonable mixture will by around 20% PuO(2) and 80% ThO(2) with a k(eff) = 1.2864. This mixed fuel would allow full power reactor operation for >20 years and burn-up grade can reach 136 000 MW.D/t. (3) Reactor grade plutonium: Third series of criticality calculations are conducted with fuel compositions made of thoria and reactor grade PuO(2), where PuO(2) is varied from 1% to 100%. Reactor becomes critical by 8% PuO(2) content. One can achieve k(eff) = 1.2670 by 35% PuO(2) and would allow full power reactor operation also for >20 years and burn-up grade can reach 123 000 MW.D/t. (4) Minor actinides in the spent fuel of LWRs: Fourth series of criticality calculations are conducted with fuel compositions made of thoria and MAO(2), where MAO(2) is varied from 1% to 100%. Reactor becomes critical by similar to 17% MAO(2) content. Reasonably high reactor criticality (k(eff) = 1.2673) is achieved by 50% MAO(2) for a reactor operation time of 15 years with a burn up of 86 000 MW.D/t without fuel change. On that way, the hazardous nuclear waste product can be transmuted as well as utilized as fuel. (C) 2010 Elsevier Ltd. All rights reserved.Article Citation - WoS: 12Citation - Scopus: 14Neutronic Investigations of a Laser Fusion Driven Lithium Cooled Thorium Breeder(Pergamon-elsevier Science Ltd, 2014) Sahin, Sumer; Sarer, Basar; Celik, YurdunazThe paper investigates the main parameters of a Laser Inertial Confinement Fusion Fission Energy (LIFE) driven thorium breeder. A similar blanket to the (LIFE) engine design in Lawrence Livermore National Laboratory is chosen in order to allow mutual feedback between two geographically separated teams towards a more advanced and improved design under consideration of totally independent views. In the basic design, frozen (D,T) fusion fuel ice is shot to the center of 5 m diameter spherical fusion reactor chamber cavity in pulsed mode (10-30 Hz). Fusion fuel burns through direct or indirect laser beam irradiation. The first wall surrounds the fusion chamber and is made of S-304 steel (2 cm). The fusion reactor cavity is kept in high vacuum. It is followed by a natural lithium coolant zone. A 2nd S-304 layer (2 cm) separates the lithium zone on the right side from the graphite reflector (30 cm). The outer boundary of the graphite reflector is also covered with a 3rd S-304 layer (2 cm). The calculations have been performed for a fusion driver power of 500 MWth with the last available version of MCNP, namely with MCNPX-2.7.0. In the first calculation phase, the thickness of the natural lithium coolant-tritium breeder zone (MU has been varied as 50, 60, 70, 80, 90 and 100 cm to select the coolant thickness Delta R-Li; to have a satisfactory tritium breeding ratio (TBR) for continuous fusion reactor operation. For a pure fusion blanket without any fissionable elements in the coolant, TBR values are calculated as 1.237, 1.312, 1.370, 1.415, 1.449 and 1.476, respectively, for corresponding coolant thicknesses. A Delta R-Li value of 50 cm would keep TBR > 1.05 for self-sustaining tritium supply. These Delta R-Li values lead to blanket energy multiplication values of M = 1.209, 1.216, 1.219, 1.222, 1.223 and 1.224, respectively, and have been calculated, as a result of exoenergetic neutron absorption in Li-6. For coolant thickness values >50 cm, the increase of "M" would remain minor. In the second phase, ThO2 has been suspended in the form of micro-size tristructural-isotropic (TRISO) particles in the lithium coolant for U-233 breeding. TRISO fuel has the great advantage of high mechanical stability. Furthermore, fission products will be separated from the coolant. TRISO particles have been dispersed homogenously in the lithium coolant with volume fractions V-tr = 1, 2, 3, 4, 5 and 10 vol-%. Calculations with Delta R-Li = 50 cm and by variable V-tr result with TBR = 1.229, 1.222, 1.214, 1.206, 1.1997 and 1.1622, respectively. Parasitic neutron absorption in Thorium decreases the TBR values. For V-tr < 5 vol-% TRISO in the coolant, the increase of the neutron absorption in thorium will be compensated to a great degree through neutron multiplications via Th-232(n,f) and Th-232(n,2n) reactions so that the sacrifice on TBR remains acceptable. However, for V-tr 5 TRISO vol-%, neutron absorption in thorium reduces TBR drastically. On the other hand, the blanket energy multiplication M increases with thorium volume fraction, namely as M = 1.2206, 1.2322, 1.2426, 1.2536, 1.2636, 1.3112 for respective TRISO volume fractions due to the contribution of fission energy. Fissile fuel productions in the blanket are calculated as 17.23, 33.09, 48.66, 64.21, 79.77 and 159.71 U-233 (kg/year), respectively. (C) 2014 Elsevier Ltd. All rights reserved.Article Citation - WoS: 11Citation - Scopus: 14Energy Multiplication and Fissile Fuel Breeding Limits of Accelerator-Driven Systems With Uranium and Thorium Targets(Pergamon-elsevier Science Ltd, 2015) Sahin, Sumer; Sarer, Basar; Celik, YurdunazThe study analyses the integral U-233 and Pu-239 breeding rates, neutron multiplication ratio through (n,xn)- and fission-reactions, heat release, energy multiplication and consequently the energy gain factor in infinite size thorium and uranium as breeder material in an accelerator driven systems (ADS), irradiated by a 1-GeV proton source. Energy gain factor has been calculated as M-energy = 1.67, 4.03 and 5.45 for thorium, depleted uranium (100% U-238) and natural uranium, respectively, where the infinite criticality values are k(infinity) = 0.40, 0.752 and 0.816. Fissile fuel material production is calculated as 53 Th-232(n,gamma)U-233, 80.24 and 90.65 U-238(n,gamma)Pu-239 atoms per incident proton, respectively. The neutron spectrum maximum is by similar to 1 MeV. Lower energy neutrons E < 1 MeV have major contribution on fissile fuel material breeding (>97.5%), whereas their share on energy multiplication is negligible (0.2%) for thorium, depleted uranium. Major fission events occur in the energy interval 1MeV < E < 50 MeV. Copyright (C) 2015, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.
