مجله علوم و فنون هسته ای
سال چهلم شماره 4 (پیاپی 90، زمستان 1398)

Three fresh fuel rods containing pellets inside zirconium tubes with three different enrichments and different dimensions have been evaluated using neutron radiography examinations at the Tehran Research Reactor. To obtain the information of the internal structure of the fuel rods, two different imaging methods, based on using single coated radiography film and phosphorous imaging plate were applied. The quantitative and qualitative evaluations of the fuel rods have been made using neutronic images of these examinations. In the qualitative evaluation of the images, the internal components of the fuel rod, such as pellets, springs, and end plugs, were well visible. The single coated radiography film had a better spatial resolution rather than the image plate so that the internal details of the rods and the gaps between the pellets were clearly detectable. In the quantitative evaluation, the pellets dimensions, the gaps between pellets, and the dependence of the absorption cross-section with the pellets enrichment have been measured and compared with the manufacturer specifications. This information was in good agreement with each other.

In this paper, for recovery and purification of uranium from the slag, three simple operations, including heat treatment at low temperature, leaching operations at the ambient temperature, and uranium sedimentation in conventional methods, as well as the combined sedimentation method at the ambient temperature were proposed. The overall role for each of these operations has been studied on the purity of the manufactured products. During the heat treatment, the combination of the insoluble U4+</sup> in the slag structure was oxidized to soluble uranium compounds. Then, with the leaching process and using a dilute nitric acid solution, ammonium bicarbonate solution and methanol, the separation of uranium from the saturated solid phase was performed. The leached uranium in the presence of the fluorine ions in the form of AUC(ammonium uranyl carbonate), ADU(ammonium diuranate) was precipitated with high purity and high efficiency, and a very pure U3</sub>O8</sub> containing fluorine concentrations of less than the permitted limit in the nuclear fuel pellet was used. The results of the analysis of the U3</sub>O8</sub> shows that the elements that affect the uranium enrichment process and the fuel performance is decreased under the permitted limit.

Urania nanostructures were synthesized by a facile, which is a simple and clean and straightforward deposition method, for two different deposition time durations. The morphology and structures of the products were characterized by the X-ray diffraction analysis (XRD) and Scanning Electronic Microscopy (SEM). The SEM images indicated that the morphology of the synthesized samples for 10 minutes was composed of a coin-like structure with a nano-scale dimension in a narrow- size distribution. The results indicated that the deposition time affects the morphology while it does not affect the structure. The XRD results identified the sample structures as UO2 </sub>crystal. The chemical composition of different points of the sample surface was determined by the energy dispersive spectroscopy (EDS) technique and the results clarified that the samples have a homogeneous composition of uranium oxide. The synergistic properties of the substrate surface, and uranium ions are responsible for the formation of an outstanding and a novel structure.

Holmium-loaded AcAc nanoparticles are potential agents for radionuclides endoradiotherapy because of their low density, biodegradability and favorable radiation characteristics. In this study, production, quality control and biodistribution studies of 166</sup>Ho-AcAc nanoparticles have been presented. Firstly, the stable 165</sup>Ho acetylacetonate (AcAc) spheres were prepared by the solvent evaporation technique. The 165</sup>Ho-AcAc nanoparticles were converted to the 166</sup>Ho-AcAc by irradiation in the Tehran Research Reactor. The morphology, stability, and structural parameters of the complex were investigated by SEM, ITLC, IR and XRD, respectively. The complex solutions (100 μCi/100 μl) were injected intra-tail into rat followed by scarification studies post- injection. The results indicated that the 166</sup>Ho-AcAc nanoparticles were prepared successfully with an optimal mean particle size of 70-100 nm and displayed a smooth surface with a high radiochemical purity of more than 97%. The complex was stable at 4ºC, human serum, PBS buffer, and room temperature. The most upper %ID/g of the 166</sup>Ho-AcAc nanoparticles was observed in the liver. Our data showed that the AcAc nanoparticles could be made in the optimal size range for the laser irradiation, and their ability to retain 166</sup>Ho makes them attractive agents for endoradiotherapy.

A useful benchmark for the reliability of gamma spectrometry results is to provide measurement uncertainty. Due to the importance and necessity of radiation monitoring in water resources, this research has been oriented toward providing measurements of the gamma- emitting radionuclides along with introducing the expression for the uncertainty that appeared in these measurements. To calculate the uncertainty of the activity measurements in water, a sample, where its radioactive elements were obtained from the PolAtom Company, was used. The calculations were performed based on the 661 keV peak of 137</sup>Cs radionuclide and a high-purity germanium detector (HPGe). The investigations show that the factors affecting the measurement uncertainty are composed of two parts, including counting with the gamma spectroscopy system and sample preparation, where each of these parts comes from several sources of uncertainty such as uncertainties associated with the counting process, efficiency calibration, emission probability, the counting correction factors, and the mass measurement. The results of analyses show that the relative uncertainty is about 3.7% (Coverage factor = 1) for a water sample with an activity of 425 Becquerel from 137</sup>Cs.

The dynamic adsorption behavior of granular activated carbon and 5Å molecular sieve adsorbers on xenon adsorption has been studied. The goal was to design and fabricate an absorber pack bed with optimized conditions. To measure the xenon in the column output contains adsorbent, a chromatography apparatus equipped with a thermal conductivity detector was used. The effect of isotherm gas flow rate and temperature variations at a constant flow velocity of gas on the dynamic adsorption process were studied. Variables such as range of the mass transfer zone and range of the unused bed have been calculated using breakthrough curves. The Langmuir model was used to predict the required absorber quantity and proper adsorption process by calculating the adsorption capacity of the absorbent. The results have shown an appropriate consistency with the model outputs, and a better adsorption performance was approved for the granular activated carbon absorber.

Thorium is an actinide substance with an atomic number of 90. Natural thorium is radioactive and, although not fissile, it undergoes a nuclear reaction (n, γ) and then beta radiation into a fissile material of the uranium. In this paper, some thermodynamic properties of the thorium have been investigated. On the other hand, the Equation of State (EOS) is an essential and suitable tool for studying the thermo-physical behavior of the materials and predicting them in different conditions in terms of pressure, temperature and amount. At present, there are different equations of state that can be categorized as theoretically, empirically, and semi-empirical. The purpose of this paper is to study some thermodynamic functions of thorium in liquid-vapor equilibrium such as vapor pressure, saturated liquid and vapor density, enthalpy and internal energy of vaporization using equations of state in the van der Waals model. In this model, the thermodynamic behavior of the materials is due to the contribution of the attractive and repulsive forces, which itself  is represented as a sum of the aforementioned statements mentioned above in a compressibility factor. In this research, we use the van der Waals equation, Berthelot equation, and the Radilich- Kwang equation. Our studies show the data obtained from Berthelot equation is in better agreement with experimental data for the studied thermodynamic functions quantitatively and qualitatively.

In this study, the electron structure of the α-Al2</sub>O3</sub> rhombohedral graft has been investigated. The alpha-alumina structure belongs to the space group R3c and the rhombohedral with two units of formula (10 atoms) in the primary unit cell. Although the most widely used structure is hexagonal, it consists of 12 aluminum atoms and 18 atomic oxygen units, six units of formulas. The role of defects in the crystalline network, especially the vacancy defect, is investigated in this work. The band structure changes are evaluated in the absence of one of the O or Al atoms. The calculations showed that α-Al2</sub>O3</sub> has a direct transition at Γ, and the energy gap obtained from the density functional theory (DFT) method is 6.3 eV. Also, the depletion effect of O is higher than that of Al on the crystal electron structure: α-Al2</sub>O3</sub>:C, and is useful in increasing the response of this crystal as a detector.

Since the discovery of graphene in 2004, two-dimensional (2D) materials have attracted broad interest due to their outstanding electronic and optical properties. In 2014, a new carbon allotrope named penta-graphene ids theoretically was predicted. The advent of penta-graphene inspired various explorations for new pentagonal 2D nanostructures. In this paper, by using the first- principles calculations based on the density functional theory as implemented in Wien2K, Quantum Espresso, and Material Studio codes, a new two- dimensional pentagonal SiGeP2 monolayer is predicted. The structural, kinetic, and thermal stabilities of the newly found monolayer are evaluated and confirmed by cohesive energy computation, phonon dispersion calculation, and first- principles molecular dynamics simulations, respectively. The electronic properties investigations reveal that the predicted monolayer has a strain tunable indirect bandgap of 2.95 calculated by the GGA-PBE level of theory. Through, the presence of a narrow phonon bandgap between acoustic and optical modes suggests its application in electro-mechanical resonators.

Due to the high refractive index and smooth surface of Polyester fibers, a significant fraction of the incident light is reflected from their surfaces. Thus, dyeing of these fibers with dark colors, mainly black, makes it a difficult tasks. High surface reflectance of Polyester microfibers reveals that appearance of these fibers is seen paler in consequently comparison to the conventional polyester fibers, and consequency it is required to use a latge amount of color to obtain the same color depth. In this study, upon creating surface roughness by laser beams treatment, as a new and environmental friendly method, was investigated to increase the dark color depth in the dyeing of polyester fabrics. An Argon Fluoride laser was used for the irradiation of the samples. The samples were prepared for evaluating the effects of the number of laser pulses, radiation before and after dyeing. The changes in the color depth of samples were analyzed through surface morphology with SEM images, and crystallinity index and crystal size with X-Ray diffraction. The results from spectra data showed that the reflection at different areas of the reflectance spectrum was reduced by increasing the number of laser pulses irradiation. The maximum deep shade in the black chromic of polyester fiber was achieved at the optimum value of 15 laser pulses

The study zone is a part of 1:100000 Anarak map which is located in the east of Isfahan province, at 10 km North of Anarak town. The Structures of this Zone is formed in Anarak-Khor region and are affected by the movement toward the north of Arabian plate, and activation of two strike-slip faults (Dorouneh and Biabanak) as a result of the mentioned movement. There is thrust fault in Chahshoureh with the east-west direction. This fault is not only a thrust but also it has during the different duration, dextral component, and then instal components. Polymetal mineralization is restricted to the hanging wall and into vein and veinlet of the listwanites of the study zone. Litswanites are uncommon carbonated rocks that forms from the alteration of ultramafic units and are abundant in silicic-carbonated threads. Ophiolites of this area belong to the ring ophiolites of central Iran. In this study, the direction of an effective paleo-stress field is reconstructed with the collecting data from slickenlines of faults and processing them by using inversion method. Trend and position of principle paleo stress axes are calculated from analysis of slickenlines by using T-tecto3 software, and it is found a that listwanites has formed in  a tear fault. As the tectonic regime of the study zone show an iterative model it could be listwanites are forming is the similar way and restricting U- mineralization to their veins and veinlets. Also, according to the same forming, it could be concluded that in the west listwanites we have a poly-metal and U-mineralization.

Nowadays, one of the essential needs of human societies is the need for energy. Our country has also turned to new sources of energy supplies, i.e., the establishment of nuclear power plants in the direction of industrialization and energy supply. In this research we are reporting the discovery of radioactive elements in the western part of Kerman province. The study area is located at 160 km southwest of Kerman and 40 km north of Sirjan. This range is longitudinal, 55° 30' 00'' - 56° 00' 00'' eastern and 55° 30' 00'' - 56° 00' 00'' north latitude in 100,000 sheet of Pariz geological map. In this study, various methods such as mixture tuned matched filtering (MTMF), and orthogonal subspace projection (OSP) were applied for the process of the remote sensing data, and single-variable methods were also used to process the radiometric data. The results have indicated the high potential of the Sentinel 2 in showing the alterations associated with the uranium deposits. Also, due to the geology of the area and the alteration holes and the cross-sectional study of the mixture tuned matched filtering regulation, the MTMF method has been able to show the argillic alteration in the Sentinel 2. According to the geology of the area, these images have the proper potential to separate sandstones and silica gravel from other units. Finally, the promising areas for radioactive elements were identified and preserved. Also, due to the process validation, the previous field surveys from the area were also investigated, and the presence of high levels of radioactive elements in the area was confirmed.

In this paper, a one-dimensional simulation for discus plate dielectric barrier discharge (DBD) is done by COMSOL Multiphysics software. The effects of different parameters such as voltage, frequency, dielectric thickness, dielectric constant and electrode’s material on the temperature and density of electrons are investigated, it is found that secondary electron emission coefficient of the electrode, dielectric constant and the thickness of dielectric have a direct impact on the density of electron. The voltage increment from 5 to 50 kV, causes electron density growing from 4×1017</sup>m-3 </sup>to 3.2×1018</sup>m-3</sup>. Based on this study, electron density could reach up to the orders of 1018</sup>m-3</sup> by optimizing material and dimensions of dielectric and electrodes without applying high voltage and frequency which results a significant lower production cost.

The management of waste produced in the reactor is an essential aspect of the nuclear fuel cycle. In this research, it has been tried to reduce the amount of reactor waste at the end of the cycle without substantial changes in the fuel dimension and the core structure of the research reactor. Minimized the heat generation. The MCNPX2.6 code is used to calculate the fuel consumption and neutronic parameters of the reactor core. The results show that without any significant change in the structure of the reference core, the amount of waste decreases only by increasing the fuel enrichment and reducing the reactor power. In this study, two core models are proposed and investigated. The waste activity at the end of the cycle in the converted reactor cores reaches 15% -19% of its original value in the reference core. Moreover, fuel burn- up has increased up to 32% -40% relative to the reference core.

The genome of a plant is the most critical factor to control bakery- quality trait in wheat, where it can bemade by applying genetic variation upon using mutagens for its improvement. In this study, chemical and Farinograph experiments were investigated in T-66-58-60, O-64-1-10, RO-1, RO-3 and RO-5 lines from Tabassi, Omid, and Roshan cultivar, respectively. Also, the sigmoid transfer function was used for the assessment of factors by the model of feed-forward neural network with training method of levenberg-Marquardt algorithm. The chemical traits of Zeleny number, the hardness, wet gluten and protein content in the RO-3 line increased significantly compared with the control. Also, water absorption percentage and valorimeter value increased substantially in the O-64-1-10, whereas it was shown that the dough softening after 10 and 20 minutes decreased significantly compared with the control. The protein content, bread volume, Farinograph quality number and E10 properties had the most significant impact on the neural network model. The results show a positive effect of the irradiation on the improvement of dough quality properties.