Sharif Digital Repository

Natural boron consists of two stable isotopes, mass 10 (19.3%) and mass 11 (80.7%). 10B isotope has a large thermal neutron capture cross-section and it therefore, used widely in such aspects as modern industry, military equipment, medical science and so on. specially the demand of atomic energy industry for the boron isotope is increased severely. So the separation of 10B from natural boron has received very wide attention at present. There are many kinds of methods on the boron isotopes separation, such as chemical exchange reaction and distillation in boron trifluoride method, ion exchange in boric acid solution method, counter current recycle membrane cascades in boron trifluoride... 

The most abundant source of deuterium, of course, is natural water. Other potential natural sources are natural gas and petroleum. Of these, natural water is by far the most significant. Until 1943, all the heavy water produced commercially was made by electrolysis. The largest single producer of heavy water was the Norsk Hydro Company, which operated the world's largest electrolytic hydrogen plant at Rjukan, Norway. In a detailed laboratory investigation of the effect of cell variables on the deuterium separation factor in electrolysis of water, Brun and co-workers [B13] have found that a: depends on the cathode material, electrolyte composition, and cell temperature, generally as... 

Uranium dioxide (UO2) has been widely used as nuclear fuel in water cooled reactors since 1960s. UO¬2 is a refractory oxide with a melting point in excess of 28000C and therefore, requires high sintering temperature around 17000C in a hydrogen atmosphere for several hours. In the conventional method, the sintering is incorporated with indirect heating of green pellets in a refractory-type electrical resistance furnace. This furnace, however, uses a large number of expensive heating elements and refractory materials to achieve and maintain the high temperature for a long time. Moreover, it consumes much electrical energy and time. Since nanocrystalline materials contain a large fraction of... 

One of the challenging issues in Iran's nuclear talks and Group 5+1 countries is the amount of Iran's enrichment capacity and the number of centrifuges needed to meet this demand. In this regard, Iran has recently announced that the basis for determining its enrichment capacity is the supply of fuel for the Bushehr power plant.Modeling and optimizing of gas centrifuge cascade is one of the most important problems in fuel cycle and isotope separation fields. To achieve this goal it is needed to comprehend of single centrifuge operation. Knowing the effectofsingle centrifuge parameters, it is easy to design a desired cascade. Minimizing the number of machines in the cascade is an anticipated... 

Lithium has two stable isotopes, 6Li and 7Li. Abundance of these isotopes are 7.53% and 92.43% respectively. Each isotope has an important role in nuclear industry. For example, 6Li compounds is used in production of tritium in nuclear fusion reactors coated with DT fuel and as fuel in nuclear fusion reactors that operate with laser inertial confinement method applied. 7LiOH is used to adjust the pH of the fluid coolant in light water reactors and also in Breeding Reactors. Lithium isotope separation in different ways so far been brought into operation. The other aspect to this work, it can be both continuous and batch for action. Lithium isotopes for the first time by electrolysis using... 

I-131 isotope is one of the most significant radio medicines for treatments of the thyroid cancer and nuclear tomography of thyroid. As for purification of this radioisotope several methods have been developed among which adsorption-desorption on metallic copper is the most promising. The current study is aimed at elaboration of the kinetics behavior of the different types of metallic copper for adsorption of iodine vapor. The used copper samples included plain and silica-supported Cu nanoparticles as well as micronized copper. The silica-supported Cu nanoparticles were prepared by impregnation of highly porous silica (≈500 m2/g) in Cu(NO3)2 solution, heating of the solution to above... 

The main methods have been used clinically for cancer treatment are included: surgery, chemotherapy, radiation therapy and hyperthermia. Hyperthermia (heat therapy) treatment method in which by raising the temperature of the tumor it removed. Magnetic hyperthermia is known as a kind of hyperthermia that have been represent appropriate results. In this study, using iron oxide nanoparticle coated with graphene for cancer treatment under a magnetic field of the laser. In the first stage, graphene oxide nanosheets and nanoparticles Magntayt are synthesized by chemical oxidation and co-precipitation, respectively. At the end, the nanoparticles on the substrate of graphene layer is obtained... 

In this thesis, a computer program is produced to measure the activity of 137Cs and 60Co radionuclides in waste packages generated at Bushehr Nuclear Power Plant (BNPP). In this program, the activity of waste drum was calculated by dividing the waste matrix into very small identical cubic cells, and each cell was considered as a point source (in the center of the cell). The activity was calculated using the theory developed by Krings & Mauerhofer. Detection efficiencies were calculated by the developed program at different conditions of a) different detector distance from drum surface, b) different collimator length, c) different cell size and d) up to 4 segment number. The results were... 

One layer mirrors are inexpensive and perform robustly across a broad range of angles, wavelengths, but they exhibit limited reflectivity. Multilayer interference mirrors are routinely used for optical applications requiring high reflectivity and wavelength selectivity. Although they can be designed to achieve a wide range of optical characteristics. One of the main applications of this multilayers in accelerators is guide outpot beamline to receive user. We can optimize these mirrors to give hight reflectivities, and outpot beam with reflect in canal that is equiped this mirrors reach to user. Conditions such as: material of layers, thickness and number of layers, surface roughness, …etc.... 

In this thesis, desublimation (deposition) of xenon gas has been studied. Through the past decades, desublimation, became one of the important methods of separation. High purity products and applicability when common methods of separation, as distillation, are not applicable, make desublimation more efficient. Heat transfer phenomenological study of direct phase change of gas to solid (desublimation), evaluation of variation of different parameters during the phase change and finally comparison of experimental results of desublimation and mathematical modeling data are the main considerations in present thesis. Because of low cost and accessibility and heat transfer phenomenological study... 

Centrifuge is a method in which great gravitational-like forces are used. Gravitational forces which cause molecules to move and are relevant to molecular weight; can cause isotope separation. The separation of light isotope from heavy one is done with a centrifugal field which produces a pressure gradient for the gas mixture. Pressure gradient is different for each of the isotopes due to the dependence of pressure gradient to the mass of the materials. But the separation in this way is very limited. The capacity of separation can be brought up by producing an additional axial flow in the rotor. This rotational flow can be produced with internal or external incitement. Rotational flow with... 

Uranium conversion process is one of the most important stages in nuclear fuel cycle. The Uranium Conversion Facilities (UFC) of Iran is located in Isfahan. In this plant, the Yellowcake (impure uranium oxide, U3O8) is converted to Uranium hexa-fluoride, UF6. During the process, considerable amounts of uranium-containing liquid waste are generated. This liquid waste was collected in evaporation pools inside the UCF Plant. In the course of time, a thick layer of precipitated salt form in bottom of the pools which are collected and stored in drums inside a building. This solid waste contains uranium at concentration levels much higher than that permitted for land disposal of the waste.... 

Nanoparticles have attracted the attention of many researchers because of the distinct physical and chemical properties. Besides the traditional applications in plastic reinforcement, fluid rheological additive, etc., the nanoparticles could be applied to many new fields and high-functional devices. Various chemical methods have been employed for the production of nanoparticles with narrow size distribution, such as co-precipitation, micro-emulsion, electrochemical synthesis, hydrothermal synthesis, sol–gel processing, flame spray pyrolysis, plasma chemical vapor deposition (CVD), hot-soap method and electrospray pyrolysis. But most of them have some problems so that only a few of them... 

The leaching process is the first stage in the process of extracting uranium out of the ore. The leaching, based on the used material is divided into two main methods of acidic and alkali leaching. Each of these two techniques have their own pros and cones. It is notable that due to lower costs, and faster kinetics, the acid leaching is the first option of the mines unless the percentage of carbonates (and the other acid-soluble materials) in the ore are too high that makes this process uneconomical because of higher acid consumption. The kinetics of the acid leaching of the uranium depends on various parameters such as acid concentration, the particle size, exposure time and the temperature... 

One of the main uranium separations of ore that uranium percent application of enhanced design strategies in the industrial cracking furnaces are of practical interest for oil, gas and petrochemical industries. For such engineering purposes the exact simulation of temperature, species concentration and flow fields in the furnace is essential. In this paper, a study was performed to simulate 3D flue gas flow pattern, temperature and species concentration field in the radiation section of an industrial cracking furnace using the computational fluid dynamics (100-500) ppm technique. The steady-state Reynolds Averaged Navier–Stokes (Resin in pulp)equations were solved, in a finite volume scheme,... 

The major features of batch sublimation were investigated in an experimental-theoretical study. An experimental setup with real-time displays, sublimated dry ice blocks of different sizes, with circular or rectangular geometries. When temperature of hotplate was changed from -30 to 200 oC, heat transfer coefficient “hsub” decreased from 126 to 70 W/m2K, while thermal flux increased, linearly. Weight and area of the block had a positive/negative effects on “hsub”, respectively. In theoretical part, at first, two “linear-gradient” and “cubic” models were developed by a combined mass-momentum-energy balance. The latter used Von Karman temperature profile, and in cases of circular and...