Browsing by Author "Ozdemir, Omer Faruk"

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Calculation of Photo-Nuclear Reaction Cross Sections for 16o
(E D P Sciences, 2015) Arasoglu, Ali; Ozdemir, Omer Faruk
Because of the high thermal expansion coefficient of uranium, the fuel used in nuclear power plants is usually in the form of UO2 which has ceramic structure and small thermal expansion coefficient. UO2 include one uranium atom and two oxygen atoms. After fission progress, total energy values of emitted gamma are about 14 MeV. This gamma energy may cause transmutation of O-16 isotopes. Transmutation of O-16 isotopes changes physical properties of nuclear fuel. Due to above explanations, it is very important to calculate photo-nuclear reaction cross sections of O-16. In this study; for (gamma,p), (gamma,np), (gamma,n) and (gamma,2n) reactions of O-16, photo-nuclear reaction cross-sections were calculated using different models for pre-equilibrium and equilibrium effects. Taking incident gamma energy values up to 40 MeV, Hybrid and Cascade Exciton Models were used for pre-equilibrium calculations and Weisskopf-Ewing (Equilibrium) Model was used for equilibrium model calculations. Calculation results were compared with experimental and theoretical data. While experimental results were obtained from EXFOR, TENDL-2013, JENDL/PD-2004 and ENDF/B VII.1 data base were used to get theoretical results.
Comprehensive Natural Radioactivity and Pollution Risk Assessments of Aquatic Media and Sediment in Lake Van (T?rkiye)
(Pergamon-elsevier Science Ltd, 2023) Zorer, Ozlem Selcuk; Yorgun, Nergiz Yildiz; Ozdemir, Omer Faruk; Ogun, Erdal; Aydin, Harun; Atici, Ataman Altug; Elp, Mahmut
This paper studies the radionuclide (137Cs, 226Ra, 232Th, 40K) activity concentrations and gross radioactivities in waters and sediments of Lake Van, which is the third largest closed lake (with no natural or artificial outlet) within the Earth. The physico-chemical parameters were measured and evaluated in the lake waters. The mean gross alpha activities in surface, middle and bottom waters are 0.04, 0.03 and 0.03 Bq/L, respectively, and in the same order, the mean gross beta activities are 0.30, 0.23 and 0.33 Bq/L, respectively. In sediment samples, the mean activity concentrations were measured as 1.98 Bq/g for gross-alpha, 3.46 Bq/g for gross-beta, 48.3 Bq/kg for 226Ra, 32.0 Bq/kg for 232Th, 540.1 Bq/kg for 40K and 25.9 Bq/kg for 137Cs. The radiation hazard parameters values based on the measured activities were calculated and Raeq values are lower than the world average value in all samples, while Dout and AED values are relatively high in some sediment samples.
Determining Radiological Hazards Due To the Natural Radioactivity in Building Materials Used in Van, Turkey
(Parlar Scientific Publications (p S P), 2018) Yildiz-Yorgun, Nergiz; Gur-Filiz, Filiz; Ozdemir, Omer Faruk; Oto, Berna
The activity concentrations of building materials commonly used in Van province of Turkey were analyzed by using NaI (T1) detector. The observed highest values for Ra-226, Th-232 and K-40 activity concentrations of these samples were determined as 77.62 +/- 8.12 (Ahlat stone 3), 54.72 +/- 6.02 (Ahlat stone 3) and 1344.85 +/- 120.97 (Ahlat stone 2) Bq/kg, respectively, and compared with data related to samples collected from different part of the world. Moreover, the radium equivalent activities (Ra-eq), the indoor absorbed dose rate in air (D-in), indoor annual effective dose equivalent (AEDE(in)), the external hazard index (H-ex), the internal hazard index (FLO and he gamma index (1(gamma)) associated with the natural radionuclide were calculated to assess the radiation hazard of the natural radioactivity in the building materials. According to our results, the building material used in Van is safe to use in construction due to an acceptable limit values for human health considerations.
The Electronic, Structural, and Optical Properties of Canb2o6 Compound: Theoretical Study
(Wiley-v C H verlag Gmbh, 2021) Duman, Ubeyt; Aycibin, Murat; Ozdemir, Omer Faruk
Based on the density functional theory (DFT) as incorporated in the Wien2k package, the lattice parameters and atomic position of calcium niobate (CaNb2O6) were optimized. Furthermore, the electronic, optical, and structural properties of the relaxed compound were calculated. Relaxed calcium niobate presents a direct band gap with 3.5 eV, which makes it a good candidate for photovoltaic applications. The DFT calculation reveals that the O atoms make the major contributions in the valence band, while Nb and Ca atoms are the dominant contributors in lower and upper portions of the conduction band, respectively. Moreover, the optical properties of compounds such as refractivity, dielectric constant, reflectivity, etc. are calculated and discussed in detail.
(N,p), (N,2n), (N,d), and (N,α) Cross-Section Calculations of 16o With 0-40 Mev Energy Neutrons
(E D P Sciences, 2015) Ozdemir, Omer Faruk; Arasoglu, Ali
Oxygen is one of the elements which interacts with emitted neutrons after fission reactions. Oxygen exists abundantly both in nuclear fuel (UO2) and moderators (H2O). Nuclear reactions of oxygen with neutrons are important in terms of stability of nuclear fuel and neutron economy. In this study, equilibrium and pre-equilibrium models have been used to calculate (n,p), (n,d), (n,2n) and (n,alpha) nuclear reaction cross-sections of O-16. In these calculations, neutron incident energy has been taken up to 40 MeV. Hybrid and Standard Weisskopf-Ewing Models in ALICE-2011 program, Weisskopf-Ewing and Full Exciton Models in PCROSS program, and Cascade Exciton Model in CEM03.01 program have been utilized. The calculated results have been compared with experimental and theroretical cross-section data which are obtained from libraries of EXFOR and ENDF/B VIII.1.
Neutron Cross Section and Emission Spectra Calculations of Na Nucleus
(Springer, 2014) Arasoglu, Ali; Ozdemir, Omer Faruk
Flibe (Li2BeF4) and Flinabe (LiFNaFBeF2) are molten salt which are used as a first wall and blanket in advanced power extraction. Since they have low vapor pressure at high temperature and don't pollute plasma. Moreover, they are used as a coolant material due to their high thermal cycling capacity. There are lots of benefits of using liquid wall such as reducing cost, increasing the reactor power and extending the life time of first steel wall. Being in Flinabe (LiFNaFBeF2) molten salt, (23) Na is also considered as a coolant material in fast reactors. Therefore, the reaction including neutron and (23) Na is getting important. In this study, the cross section calculations of neutron induced reactions for (23) Na were performed. Using pre-equilibrium and equilibrium models, excitation functions of (23) Na(n,p)(23) Ne, (23) Na(n,d)(22) Ne, (23) Na(n,alpha)(20) F, (23) Na(n,2n)(22) Na reactions and (23) Na(n,x alpha), (23) Na(n,xn) emission spectrums were calculated. We calculated alpha emission spectrum obtained when (23) Na nuclei projectiled with 14.1 MeV neutrons and also neutron emission spectrum emitted when (23) Na nuclei was bombardment with 14.6 MeV neutrons.
Pre-Service Physics Teachers' Metacognitive Knowledge About Their Instructional Practices
(Eurasia, 2015) Yerdelen-Damar, Sevda; Ozdemir, Omer Faruk; Unal, Cezmi
This study aims to investigate pre-service physics teachers' metacognitive knowledge about their teaching practices. The participants included six pre-service physics teachers. A taxonomy of metacognition for teaching was developed to analyze the level of pre-service physics teachers' metacognitive knowledge about their teaching practices. Analysis of data showed that pre-service physics teachers' metacognitive knowledge about their content knowledge was quite satisfactory; however, their metacognitive knowledge about instructional methods, students' pre-instructional knowledge, and the task of teaching needs to be improved. The results of the study provided evidence that metacognitive knowledge on teaching is a fruitful framework to generate interpretations about the participants' instructional processes.