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Conference Object Citation - WoS: 9Citation - Scopus: 10Comparisons of the Calculations Using Different Codes Implemented in Mcnpx Monte Carlo Transport Code for Accelerator Driven System Target(Amer Nuclear Soc, 2012) Sarer, Basar; Sahin, Sumer; Gunay, Mehtap; Celik, YurdunazThe MCNPX code offers options based on physics packages; the Bertini, ISABEL, INCL4 intra-nuclear models, and Dresner, ABLA evaporation-fission models and CEM2k cascade-exciton model. The study analyzes the main quantities determining ADS performance such as neutron yield, neutron leakage spectra, and neutron and proton spectra in the target and in the beam window calculated by the MCNPX-2.5.0 Monte Carlo transport code, which is a combination of LAHET and MCNP codes. The results obtained by simulating different models, cited above and implemented in MCNPX are compared with each other. The investigated system is composed of a natural lead cylindrical target and stainless steel (HT9) beam window. Target has been optimized to produce maximum number of neutrons with a radius of 20 cm and 70 cm of height. Target is bombarded with a high intensity linear accelerator by a 1 GeV, 1 mA proton beam. The protons are assumed uniformly distributed across the beam of radius 3 cm, and entering the target through a hole of 5.3 cm radius. The proton beam has an outer radius of 5.3 cm and an inner radius 5.0 cm. The maximum of the neutron flux in the target is observed on the axis similar to 10 cm below the beam window, where the maximum difference between 7 different models is similar to 15 %. The total neutron leakage out of the of the target calculated with the Bertini/ABLA is 1.83x10(17) n/s, and is about 14 % higher than the value calculated by the INCL4/Dresner (1.60x10(17) n/s). Bertini/ABLA calculates top, bottom and side neutron leakage fractions as 20 %, 2.3 %, 77.6 % of the total leakage, respectively, whereas, they become 18.6 %, 2.3 %, 79.4 % with INCL4/Dresner combination.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.Article Citation - WoS: 13Citation - Scopus: 14Commercial Utilization of Weapon Grade Plutonium as Triso Fuel in Conventional Candu Reactors(Pergamon-elsevier Science Ltd, 2012) Sahin, Sumer; Sahin, Haci Mehmet; Acir, AdemLarge quantities of weapon grade (WG) plutonium have been accumulated in the nuclear warheads. Plutonium and heavy water moderator can give a good combination with respect to neutron economy. TRISO type fuel can withstand very high fuel burn up levels. The paper investigates the prospects of utilization of TRISO fuel made of WG-plutonium in CANDU reactors. Three different fuel compositions have been investigated: (1): 90% ThC + 10% PuC, (2): 70% ThC + 30% PuC and (3): 50% ThC + 50% PuC. The temporal variation of the criticality k(infinity) and the burn-up values of the reactor have been calculated by full power operation up to 17 years. Calculated startup criticalities for these fuel modes are k(infinity.0)= 1.6403, 1.7228 and 1.7662, respectively. Attainable burn up values and reactor operation times without new fuel charge will be 94700, 265000 and 425000 MW.D/MT and along with continuous operation periods of similar to 3.5, 10 and 17 years, respectively, for the corresponding modes. These high burn ups would reduce fuel fabrication costs and nuclear waste mass for final disposal per unit energy drastically. (C) 2012 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.Conference Object Citation - WoS: 2Citation - Scopus: 2Radiation Source Terms of Myrrha Reactor Components and Equipment(Pergamon-elsevier Science Ltd, 2016) Celik, Yurdunaz; Stankovskiy, Alexey; Engelen, Jeroen; Van den Eynde, Gert; Sarer, Basar; Sahin, SumerIn-vessel structural components of nuclear reactors are subject to prompt and residual neutron and photon activation. The MYRRHA fast spectrum facility, when operated in sub critical mode, suffers additional activation due to a wide range of energetic particles produced in the interactions of 600 MeV-primary protons with matter. The purpose of this work was to assess the source term (activation, heating and induced radiation level) of ex core equipment and components located inside the reactor vessel. Numerous stainless steel samples uniformly distributed inside the vessel have been used to simulate the activation of equipment in order to take into account the perturbation of the neutron spectrum caused by structural materials of components and equipment. The calculated quantities were prompt and residual activation, heating, radiation dose and radiation damage. The calculations were carried out with the ALEPH2 depletion code which invokes the MCNPX code for radiation transport. Copyright (C) 2016, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.Editorial Preface To the Special Issue on "17th International Conference on Emerging Nuclear Energy Systems (icenes'2015), 4-8 October 2015, Istanbul, Turkey"(Pergamon-elsevier Science Ltd, 2016) Sahin, Sumer; Sahin, Haci Mehmet; Martinez-Val, Jose; Wu, Yican[No Abstract Available]Conference Object Citation - WoS: 8Citation - Scopus: 7UTILIZATION OF REACTOR GRADE PLUTONIUM AS ENERGY MULTIPLIER IN THE LIFE ENGINE(Amer Nuclear Soc, 2012) Sahin, Sumer; Sahin, Haci Mehmet; Acir, AdemThe accumulated reactor grade (RG)-plutonium as nuclear waste of conventional reactors is estimated to exceed 1700 tonnes. Laser Inertial Confinement Fusion Fission Energy (LIFE) engine is considered to incinerate RG-plutonium in stockpiles. Calculations have been conducted for a constant fusion driver power of 500 MWth in S-8-P-3 approximation using 238-neutron groups. RG-plutonium out of the nuclear waste of LWRs is used in form of fissile carbide fuel in TRISO particles with volume fractions of 2, 3, 4, 5 and 6 %, homogenously dispersed in the Flibe coolant. Respective tritium breeding ratio (TBR) values per incident fits ion neutron are calculated as TBR = 1.35, 1.52, 1.73, 2.02 and 2.47 at start-up. With the burn up of fissionable RG-Pu isotopes in the coolant, TBR decreases gradually. Similarly, blanket energy multiplications are calculated as M-0 = 3.8, 5.5, 7.7, 10.8 and 15.4 at start-up, respectively. Calculations have indicated prospects of achievability of very high burn up values (> 400 000 MD.D/MT).Conference Object Renewability and Sustainability Aspects of Nuclear Energy(Amer inst Physics, 2014) Sahin, SumerRenewability and sustainability aspects of nuclear energy have been presented on the basis of two different technologies: (1) Conventional nuclear technology; CANDU reactors. (2) Emerging nuclear technology; fusion/fission (hybrid) reactors. Reactor grade (RG) plutonium, U-233 fuels and heavy water moderator have given a good combination with respect to neutron economy so that mixed fuel made of (ThO2/RG-PuO2) or (ThC/RG-PuC) has lead to very high burn up grades. Five different mixed fuel have been selected for CANDU reactors composed of 4 % RG-PuO2 + 96 % ThO2; 6 % RG-PuO2 + 94 % ThO2; 10 % RG-PuO2 + 90 % ThO2; 20 % RG-PuO2 + 80 % ThO2; 30 % RG-PuO2 + 70 % ThO2, uniformly taken in each fuel rod in a fuel channel. Corresponding operation lifetimes have been found as similar to 0.65, 1.1, 1.9, 3.5, and 4.8 years and with burn ups of similar to 30 000, 60 000, 100 000, 200 000 and 290 000 MW.d/ton, respectively. Increase of RG-PuO2 fraction in radial direction for the purpose of power flattening in the CANDU fuel bundle has driven the burn up grade to 580 000 MW. d/ton level. A laser fusion driver power of 500 MWth has been investigated to burn the minor actinides (MA) out of the nuclear waste of LWRs. MA have been homogenously dispersed as carbide fuel in form of TRISO particles with volume fractions of 0, 2, 3, 4 and 5 % in the Flibe coolant zone in the blanket surrounding the fusion chamber. Tritium breeding for a continuous operation of the fusion reactor is calculated as TBR = 1.134, 1.286, 1.387, 1.52 and 1.67, respectively. Fission reactions in the MA fuel under high energetic fusion neutrons have lead to the multiplication of the fusion energy by a factor of M = 3.3, 4.6, 6.15 and 8.1 with 2, 3, 4 and 5 % TRISO volume fraction at start up, respectively. Alternatively with thorium, the same fusion driver would produce similar to 160 kg U-233 per year in addition to fission energy production in situ, multiplying the fusion energy by a factor of similar to 1.3.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.Editorial Report on the Special Issue Set2012, the 10th International Conference on Sustainable Energy Technologies, Istanbul, Turkiye (4-7th September 2011)(Pergamon-elsevier Science Ltd, 2012) Sahin, Sumer[No Abstract Available]
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