M.S. Theses
Permanent URI for this collection
Browse
Recent Submissions
Item Theory of and computer aided neutron activation analysis(Thesis (M.S.) - Bogazici University. Institute for Graduate Studies in Science and Engineering, 1983., 1983.) Sağlam, Semiha.; Altıntaş, Sabri.Neutron activation analysis, NAA, has become a widely used and important analytical technique, not only intrace analysis but also indetermining alloy elements and minor constituents. The microqualitative and quantitative analysis can usually be performed by NAA invarious fields, such as biology, criminology, geochemistry, cosmochemis try, industry etc. Thus, the field of application of the method is very wide. In this study, first the basic concepts and principles of NAB is introduced. The detection methods and various types of detectors are discussed. The use o f computers i n NAA problems are also given. Then, a predeveloped computer code, Gretel, which is set up for routine batch wise processing of spectrometric data obtained by GE(Li) detector sisintroduced. This code, programmed originally for the IBM 3701165 computer, is adopted to the UNIVAC 1106 computer in BU for further studies. The UNIVAC version of the program, the input and the out put data are finally recorded on to a magnetictape. Also, another computer code prepared for NAA, Corgam, which was studied previously is introduced briefly . The comparison of these two codes are given at the end of this study.Item Computer aided neutron activation analysis(Thesis (M.S.)- Bogazici University. Institute for Graduate Studies in Science and Engineering, 1982., 1982.) Böğrün, Haluk.; Altın, Vural.Item Uranium dioxide neclear fuel element production techniques and evalution of the related studies in Turkey(Thesis (M.S.)- Bogazici University. Institute for Graduate Studies in Science and Engineering, 1982., 1982.) Erbay, Berrin.; Avcı, H. İbrahim.Item Concentration of uranium content of the Black Sea sediments using froth flotation(Thesis (M.S.)- Bogazici University. Institute for Graduate Studies in Science and Engineering, 1982., 1982.) Behar, Selim.; Altın, Vural.The recent studies about The Black Sea Sediments sowed that it containst trace amounts of uranium. In the production of uranium metal, uranium minerals are separated from gange minerals by hydrometallurgical processes. Since the Black Sea Sediments have very low uranium content the direct application of hydrometallurgical processes in creases the reagent amounts. To overcome this problem, in this thesis work application of flotation in order to obtain a concent rate which will be rich in uranium content is studied. In flotation experimentst the effect of changes of pH, the quantity of filotation reagents and pulp density on uranium r concentration were studied. A method of uranium analysis based on spectrophotometry was chosen for the analysis of the sediments tailing and concentrate. The highest yield obtained was 31.8 % , and this recovery was obtained using 0.01148 gr Na2Si03 with 17 minutes conditioning time, 0.01 gr FeC13 with 15 minutes conditioning time and a mixture of aeropromoter reagents with 60 minutes conditioning time. The other parameters were chosen as follows : Pulp density 20 %, medium pH 8 and flotation time 5 minutes.Item Mining and transport of uranium containing black sea sediments(Thesis (M.S.) - Bogazici University. Institute for Graduate Studies in Science and Engineering, 1982., 1982.) Teziç, Sadi.; Enginol, Turan Bozkurt.Item Evaluation of gammagraphy for different materials(Thesis (M.S.) - Bogazici University. Institute for Graduate Studies in Science and Engineering, 1984., 1984.) Büyükyüksel, Sinan.; Bilge, Ali Nezihi.Garareagraphy which is a part of radiography, is one of the important and effective methods in nondestructive tes%ing and determination of exposure time in gamrnagraghy has a special importance from the point of view ofcradiographic results. The aim of this study is to evaluate the methods of expssiase time determination (ETD) then, after choosing the most reliable method, to construct ETD tables for workers in this field, There are several methods used in determination of exposme time in gammagraphy. In this study tiexposure charte method which is an experimental method and a theoretical approach is used, The theoretical method is modified by using build up factors and improved as an "alternativew method, The reason for the choice of these methods is that they are very appropriate for computer analysis so that a realistic comparison of the methods could be done, The study can be divided into two main parts, In the first step, all ETD methods were computerized for several gamma sources, films, film densities, arid materials and the results were compared. Then, in the next step, which is the experimental past of the study, some radiographs were taken with aBOUN%he methods by using a 30 Curies Cobalt-60 source and the methsd giving the best result was determined, The results obtained from the computer analysis and experiments showed that the alternative method has given the best radiographs among the other ETD methods.Item Development of a charged particle thickness gauge(Thesis (M.S.) - Bogazici University. Institute for Graduate Studies in Science and Engineering, 1989., 1989.) Uzonur, Mutlu Onur.; Bilge, Ali Nezihi.The determination of the unknown sample thicknesses by using a radioactive source is one of the most widely used non-destructive measurement methods. In this work, an attempt was made to determine the unknown thicknesses of paper sheets by using a beta source. The components of the experimental system and their configurations were determined by minimizing the scatterings and considering physical events like the absorption of beta particles taking place in the surrounding medium. A nonlinear curve fitting procedure was applied to the experimentally obtained data points in addition to the iinear least squares method. Errors were analyzed, interpreted and for some of the investigated cases only the source of error was located. Finally some suggestions have been made for further work in this subject and applications in the field of on-line measurements.Item A study of the two dimensional multigroup diffusion analysis code :|Erebus(Thesis (M.S.) - Bogazici University. Institute for Graduate Studies in Science and Engineering, 1981., 1981.) Şen, Mehmet.; Altın, Vural.Item Methods of xenon stability analysis in nuclear reactors(Thesis (M.S.)- Bogazici University. Institute for Graduate Studies in Science and Engineering, 1981., 1981.) Şener, Tamer.; Altın, Vural.The subject of this study is the constsuction of some sufficiernt conditions for Xenon stability in therinal reactors during operation, and the approximate time behaviour of the point kinetics system with feedback. The same topic had been investigated by J, Chernick, G. Lellouche and W. Wollmann[7] in 1961. It had been shown that Xenon instability remains a serious concern in the preseace of temperature damping. Later A. Z. Akpasu and P. Akhtar studied the problem in 1966 [2]. They approached the problem as one of asymptotic stability in the large for point reactors with non-linear feedback; and gave a new criterion for boundedaess of Xenon oscillations in the presence of temperature feedback, In the first three chapters basic kinetic equations are derived for the point reactor model, mainly to emphasize the extent of careful work required to obtain the mean neutron generation time. Then global stability analysis of Xenon is examined and the region of asymptotic stability in the large in the plane of equilibrium flux vs, temperature coeffioient is determined. In chapter four linear stability analysis is considered a d conditions for linear stability are determined with and without delayed neutrons; and the results axe compared. In constructing the stability conditions, various approximations arid combinations of parameters were utilized, Further, point kinetics equations are solved for certain reactor operating conditions and the time behaviour of the flux is observed in order to assess some properties such as period and amplitude of oscillations in the region of stability and instability. The results are compared with that of other workers in the field[2]. Results, plots and the discussions are given in the last chapler. Computer programs used in this work are also provided in the appendices.Item The thermal-hydraulic codes COBRA III-C and terhid and anlaysis and comparison(Thesis (M.S.)- Bogazici University. Institute for Graduate Studies in Science and Engineering, 1981., 1981.) Çağıl, Gülsevin.; Borak, Fahir.In this work the thermal-hydraulic programroes TERHID, which makes steady state and transient thermal-hydraulic analysis for plate type nuclear fuel elements , and COBRA 111-C, a computer programme for steady state and transient state therma l-hydraulic analysis of rod bundle fuel elements with subchannel approach analysed and compared. The comparison of the two programmes cover the anslysis of the conduction and the convection models, the assumptions made in the models , and the solution algorithms . The numerical applications consist of two parts. In the first part the sample problem given in TERBID is applied as input to COBRA 111-C. The transient solutions for different time increment are intercompared for this programme. In these condpart another applictaion is carried out for the identical problem using both codes by considering the effect of the inlet temperature change, inlet mass flux change and power change as a function of time during transients.Item Characterization of gammagraphic resolution in different media(Thesis (M.S.)- Bogazici University. Institute for Graduate Studies in Science and Engineering, 1986., 1986.) Cimit, Ömer Ufuk.; Bilge, Ali Nezihi.Item Thorium utilisation in gas cooled reactors(Thesis (M.S.) - Bogazici University. Institute for Graduate Studies in Science and Engineering, 1986., 1986.) Çatkan, Barbaros.; Enginol, Turan Bozkurt.Intensive effort for energy prduction through alternate paths is being spent in developed countries because of the limitedness of resources such as natural gas, petroleum, coal that make great contributions t o energy production. Nuclear energy can be noted as one of the most important amongst these alternatives. R & D work is being carried out for the purpose of reducing the reliance on the U-235 isotope and for more economical utilisation of known Uranium resources because of the limitedness of the isotope U-235 which plays an important role on today's reactor technology. In this study, the Thorium fuel cycle which offers the possibility of reducing mined Uranium ore requirements is examined in connection with the High Temperature Gas cooled Reactor concept which supports the Thorium cycle. The Pebble-Bed core which employs spherical fuel elements is particularly interesting as it provides On-Load Refuelling. A s a prelude, the first chapter provides the basic information to introduce the concept to the reader. The properties of Thorium material are described in chapter 2. Several Thorium fuel cycles are discussed in chapter 3 and the technology associated with Thorium fuel along with HER designs is introduced in chapter 4. A possible strategy utilising Thorium is examined in chapter 5. The sixth chapter covers information about current HTGR models under active development.Item Development of a thickness gauge for measuring thin materials(Thesis (M.S.)- Bogazici University. Institute for Graduate Studies in Science and Engineering, 1984., 1984.) Baytaş, A. Cihat.; Bilge, Ali Nezihi.Thickness gauges using nuclear techniques and radioactive sources are devised to measure the material thicknesses of the order of microns in a non-destructive manner without contacting the material. This allows for quality control by measuring the thickness during production and adjustment of the system in the case of a failure. The thickness gauge which is the subJect of my thesia study is designed to use gamma transmission method, In the transmission method,the set-up consists of the detector and the radioactive source placed at opposite sides of the material whose thickness is t o be measured. Unknown thicknesses can be found by using this thickness gauge with the and of calibration curves that have been prepared according to the source and the geometry used. Minhwn detection limits of various materials that can be rneaeused with this gauge have also been determined so as to give an idea about the accuracy of tne gauge.Item Analysis of the integral transport theory code gels and its application to PWR cell homogenization with the purpose of thorium conversion(Thesis (M.S.)- Bogazici University. Institute for Graduate Studies in Science and Engineering, 1981., 1981.) Albayrak, Sırrı.; Altın, Vural.Item Design and construction of a portable neutron radiographic camera(Thesis (M.S.) - Bogazici University. Institute for Graduate Studies in Science and Engineering, 1984., 1984.) Akbulut, Dursun.; Enginol, Turan Bozkurt.The subject of this thesis is to provide a coherent picture of the components and methods involved i n neutron radiography, that is by now a proven technique in non destructive testing. Having presented a detailed picture of the prioriples related to neutron radiography, design and construction of a neutron radiographic camera, containing a 241 Am - Be neutron source has been developed. In ths first chapter the methods and companents of a neutron radiography unit has been described. In chapters two, three, four and five the components of neutron radiographic facility has been considere in a detailed manner. In chapter six the design of a neutron radiographic camera has been considered and some theoretical methods have been applied to determine the thermal neutron distrition and the doserates. Finally, construct on of a neutron radiographic camera and discussion of prospects on this topic and applications have been presented in the last section.Item Analysis of gamma ray spectra from neutron activation studies(Thesis (M.S.) - Bogazici University. Institute for Graduate Studies in Science and Engineering, 1984., 1984.) Akın, H. Levent.; Altın, Vural.Neutron activation analysis coupled with Gamma Ray Spectrometry is a powerful and highlyprecise, non-destructive elemental analysis method. In this work a program package, BUCAASA, was developed for the analysis of gamma rayspectra. The first program of the package BUCAASA/FIND, using an improved version of the method of the smoothed first derivative identifies the peaks in the spectrum. The second program BuCAASA/FIT is then used for fitting a function to the peaks for the accurate determination of peak location and peak area. The function used for fitting was developed by Ciftcioglu. The third program SUCAASA/CALIBR performs energy and efficiency calibration. The constituent nuclides together with their activities are identified by the fourth program BUCAASA/NUCLIDE which is an adapted versionof SAMP080 PART 111. All of the programs are interactive and can be used for both routine and academic work. Since they are coded in standard FORTRAN 77 programming language their implementation on other computers is easy. Implementation on microcomputers requires overlaying however.