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Şahin, Sümer
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Name Variants
Sahin, Suemer
S.,Sumer
Sahin, Sumer
S., Sahin
S., Sumer
S.,Sahin
Sumer, Sahin
S.,Şahin
Ş.,Sümer
Sahin,S.
Şahin, Sümer
Şahin,S.
Sümer, Şahin
S.,Sumer
Sahin, Sumer
S., Sahin
S., Sumer
S.,Sahin
Sumer, Sahin
S.,Şahin
Ş.,Sümer
Sahin,S.
Şahin, Sümer
Şahin,S.
Sümer, Şahin
Job Title
Profesör Doktor
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Main Affiliation
Department of Mechanical Engineering
Status
Former Staff
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Scholarly Output
45
Articles
24
Citation Count
275
Supervised Theses
0
45 results
Scholarly Output Search Results
Now showing 1 - 10 of 45
Article Citation - WoS: 6Assessment of Criticality and Burn Up Behavior of Candu Reactors With Nuclear Waste Trans Uranium Fuel(Pergamon-elsevier Science Ltd, 2012) Sahin, Sumer; Ahmed, Rizwan; Khan, Mohammad Javed; Department of Mechanical EngineeringLarge quantities of nuclear waste plutonium and minor actinides (MAs) have been accumulated in the civilian light water reactors (LWRs) and CANDU reactors. These trans uranium (TRU) elements are all fissionable, and thus can be considered as fissile fuel materials in form of mixed fuel with thorium or naturanium in the latter. CANDU fuel compacts made of tristructural-isotropic (TRISO) type pellets would withstand very high burn ups without fuel change. As carbide fuels allow higher fissile material density than oxide fuels, following fuel compositions have been selected for investigations: (1) 90% nat-UC + 10% TRUC, (2) 70% nat-UC + 30% TRUC and (3) 50% nat-UC + 50% TRUC. Higher TRUC charge leads to longer power plant operation periods without fuel change. The behavior of the criticality k(infinity) and the burn up values of the reactor have been pursued by full power operation for > similar to 12 years. For these selected fuel compositions, the reactor criticality starts by k(infinity) = 1.4443, 1.4872 and 1.5238, where corresponding reactor operation times and burn up values have been calculated as 2.8 years, 8 years and 12.5 years, and 62, 430 MW.D/MT, 176,000 and 280,000 MW.D/MT, with fuel consumption rates of similar to 16, 5.68 and 3.57 g/MW.D respectively. These high burn ups would reduce the nuclear waste mass per unit energy output drastically. The study has show clearly that TRU in form of TRISO fuel pellets will provide sufficient criticality as well as reasonable burn up for CANDU reactors in order to justify their consideration as alternative fuel. (c) 2012 Elsevier Ltd. All rights reserved.Conference Object Citation - WoS: 2Citation - Scopus: 3Influence of Void Fraction on Bwr Spent Fuel Direct Recycling Scenario(Pergamon-elsevier Science Ltd, 2015) Waris, Abdul; Su'ud, Zaki; Sahin, Hacz Mehmet; Kurt, Erol; Sahin, Sumer; Department of Mechanical EngineeringPreliminary study on influence of changing void fraction (VF) on SUPEL (Straight Utilization of sPEnt LWR fuel in LWR system) scenario for boiling water reactor (BWR) spent fuel direct recycling scheme has been carried out. Several VF values of BWR have been investigated to determine the criticality of reactor. The VF values range from 20% to 60%. The fraction of spent fuel to the total loaded fuel was changed from 5% to 20%. The required uranium enrichment for criticality becomes higher with the increasing of VF as well as the enlarging of the fraction of spent fuel in loaded fuel. The neutron spectra become harder with the augmenting of VF. The plutonium and minor actinides isotopes are produced more in the reactor. Copyright (C) 2015, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.Article Citation - WoS: 12Citation - Scopus: 14Utilization of Nuclear Waste Plutonium and Thorium Mixed Fuel in Candu Reactors(Wiley, 2016) Sahin, Sumer; Sarer, Basar; Celik, Yurdunaz; Department of Mechanical EngineeringSpent nuclear fuel out of conventional light water reactors contains significant amount of even plutonium isotopes, so called reactor grade plutonium. Excellent neutron economy of Canada deuterium uranium (CANDU) reactors can further burn reactor grade plutonium, which has been used as a booster fissile fuel material in form of mixed ThO2/ PuO2 fuel in a CANDU fuel bundle in order to assure reactor criticality. The paper investigates incineration of nuclear waste and the prospects of exploitation of rich world thorium reserves in CANDU reactors. In the present work, the criticality calculations have been performed with 3-D geometrical modeling of a CANDU reactor, where the structure of all fuel rods and bundles is represented individually. In the course of time calculations, nuclear transformation and radioactive decay of all actinide elements as well as fission products are considered. Four different fuel compositions have been selected for investigations: 95% thoria (ThO2) + 5% PuO2,. 90% ThO2 + 10% PuO2,. 85% ThO2 + 15% PuO2 and. 80% ThO2 + 20% PuO2. The latter is used for the purpose of denaturing the new U-233 fuel with U-238. The behavior of the criticality k8 and the burnup values of the reactor have been pursued by full power operation for similar to 10 years. Among the investigated four modes, 90% ThO2 + 10% PuO2 seems a reasonable choice. This mixed fuel would continue make possible extensive exploitation of thorium resources with respect to reactor criticality. Reactor will run with the same fuel charge for similar to 7 years and allow a fuel burnup similar to 55 GWd/ t. Copyright (C) 2016 John Wiley & Sons, Ltd.Editorial Citation - WoS: 0Citation - Scopus: 0Editor's Report on Nurer2012, the Iii. International Conference on Nuclear and Renewable Energy Resources, Istanbul, Turkiye (20-23rd May 2012)(Pergamon-elsevier Science Ltd, 2013) Sahin, Sumer; Department of Mechanical Engineering[No Abstract Available]Article Citation - Scopus: 5Candu Reactors With Reactor Grade Plutonium/Thorium Carbide Fuel(Carl Hanser Verlag, 2011) Şahin,S.; Khan,M.J.; Ahmed,R.; Department of Mechanical EngineeringReactor grade (RG) plutonium, accumulated as nuclear waste of commercial reactors can be re-utilized in CANDU reactors. TRISO type fuel can withstand very high fuel burn ups. On the other hand, carbide fuel would have higher neutronic and thermal performance than oxide fuel. In the present work, RG-PuC/ThC TRISO fuels particles are imbedded body-centered cubic (BCC) in a graphite matrix with a volume fraction of 60%. The fuel compacts conform to the dimensions of sintered CANDU fuel compacts are inserted in 37 zircolay rods to build the fuel zone of a bundle. Investigations have been conducted on a conventional CANDU reactor based on GENTILLYII design with 380 fuel bundles in the core. Three mixed fuel composition have been selected for numerical calculation; (1) 10% RG-PuC + 90% ThC; (2) 30% RG-PuC+70% ThC; (3) 50% RG-PuC + 50% ThC. Initial reactor criticality values for the modes (1), (2) and (3) are calculated as k∞,0 = 1-4848, 1.5756 and 1.627, respectively. Corresponding operation lifetimes are ~ 2.7, 8.4, and 15 years and with burn ups of ∼ 72000, 222000 and 366000 MW.d/tonne, respectively. Higher initial plutonium charge leads to higher burn ups and longer operation periods. In the course of reactor operation, most of the plutonium will be incinerated. At the end of life, remnants of plutonium isotopes would survive; and few amounts of uranium, americium and curium isotopes would be produced. © Carl Hanser Verlag, München.Article Utilization of Reactor Grade Plutonium as Energy Multiplier in the LIFE Engine(Fusion Science and Technology, 2017) Şahin, Sümer; Şahin, Hacı Mehmet; Acır, Adem; Department of Mechanical EngineeringThe 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 S8-P3 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 fusion 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 M0 = 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).Editorial Citation - WoS: 0Citation - Scopus: 0Preface 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; Department of Mechanical Engineering[No Abstract Available]Editorial Citation - WoS: 1Citation - Scopus: 1Editor's Notes on Icenes'2013, 16th International Conference on Emerging Nuclear Energy Systems(Pergamon-elsevier Science Ltd, 2015) Sahin, Sumer; Department of Mechanical Engineering[No Abstract Available]Article Citation - WoS: 26Citation - Scopus: 28Utilization of Triso Fuel With Reactor Grade Plutonium in Candu Reactors(Elsevier Science Sa, 2010) Sahin, Suemer; Sahin, Haci Mehmet; Acir, Adem; Department of Mechanical EngineeringLarge 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 (1) 4% RG-PuO2+ 96% ThO2; CD 6% RG-PuO2 + 94% ThO2; (3) 10% RG-PuO2+ 90% ThO2; 20% RG-PuO2+ 80% ThO2; (5) 30% RG-PuO2 + 70% ThO2. Initial reactor criticality (k(infinity,0) values) for the modes (1), (2), (3), (4) and are calculated as 1.4294, 1.5035, 1.5678, 1.6249, and 1.6535, respectively. Corresponding operation lifetimes are similar to 0.65, 1.1, 1.9.3.5, and 4.8 years and with burn ups of 30000, 60000, 100000. 200000 and 290000 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% PuO2, 80/20% PuO2/ThO2, 60/40% PuO2/ThO2, and 40/60% PuO2/ThO2, 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. (C) 2010 Elsevier BM. All rights reserved.Article Citation - WoS: 0Citation - Scopus: 0Incidence of Medical Device-Related Pressure Injuries and Identification of Risk Factors in the Neonatal Unit(Elsevier Sci Ltd, 2024) Yarkiner, Zalihe; Bahar, Arzu; Sonmez, Munevver; Kapan, Emine; Sahin, Simge; Kostekci, Ezgi; Erdeve, Omer; Department of Mechanical Engineering; NursingAim: This study was conducted to investigate the incidence of medical device-related pressure injuries (MDRPIs) and the risk factors influencing their occurrence in the neonatal intensive care unit (NICU). Method: This study is a prospective, descriptive study. The research was conducted with 116 newborns between June 1, 2022, and June 1, 2023. Newborns who stayed in the neonatal intensive care unit for at least 24 h were observed daily for medical device-related pressure injuries under and around each medical device throughout their stay in the intensive care unit. The "Case Report Form," "MDRPIs Monitoring Form," "Braden Q scale for children," National Pressure Injury Advisory Panel (NPIAP) Pressure Grading, and Glasgow Coma Scale were used in the research. Results: The incidence of medical device-related pressure injuries is 35.3 % (41/116). It was found that 38.1 % (16/42) of medical device-related pressure injuries developed due to Near-Infrared Spectroscopy (NIRS) probes, and 33.5 % (14/42) developed due to medical devices related to the respiratory system. In terms of anatomical location, 38.1 % occurred on the forehead, and 23.8 % on the arm/leg. The difference between birth weight, gestational age, development of MDRPIs in newborns receiving sedation and inotropes was found to be statistically significant. Regression analysis identified gestational age (p = 0.040, OR = 0.795, 95%CI = [0.632-1.000]) as an independent risk factor for the occurrence of medical device-related pressure injuries. Conclusions: The incidence of medical device-related pressure injuries in newborns was relatively high in this study, with gestational age being the most significant risk factor for MDRPIs formation. It is crucial for neonatal intensive care nurses to consider associated risk factors while providing newborn care and implement appropriate preventive measures to reduce the incidence of MDRPIs.
