[en] In this paper two geometries for pulsed neutron counter structure have been introduced and to increase the activation counter efficiency, plastic scintillation along with silver foils was used. Cubic and cylindrical geometries for activation counter cell were modeled using MCNP4C code. In respect of absorption reaction rate in silver, the number of silver foils and the length of the counter were optimized. The optimum length of 14 centimeters had been proposed for counter cell and because of the economic aspects, the optimum number of silver foils for cubic and cylindrical geometries are 20 and 10, respectively. The optimum data were used to construct a cubic counter and the neutron yield of SBUPF1 plasma focus device was measured by this counter. Experimental results show that about 3.71*10⁷ neutrons are produced per pulse.

[en] Solid-liquid separation is one of the most important sections in mineral processing. High percentage of clay material and fine particles (-200 mesh) cause different problems in separation of uranium leach liquor from the residual solid particles in filtration unit of Bandar Abbas Uranium Plant. The laboratory tests showed that thickener is a suitable device for solid-liquid separation, after leaching unit. For this reason, thickeners were selected for separating of leach liquor from the residual solid particles. For determination of the size and number of thickeners, sedimentation experiments were performed with different Flocculent, ^Magna floc LT-25^was selected as a suitable Flocculent in 75 g/ton. The diameter of thickener was determined to be 13-14 m. In the counter current decantation, the loss percentage of uranium, using 5 thickeners, was selected to be 2.09%

[en] Cs-137 is one of the fission products that is usually released in environment after nuclear accidents. This contamination remains in environment for a long time due to long half life of Cs-137 (30 years) and can enter easily into the human food chain. A two-compartmental model was implemented to describe caesium intake and its distribution in Dicentrarchus Labrax, using a proposed differential equation model. The model included two compartments, the first compartment was the blood and the second one was the tissue. The activity of Cs-137 was undertaken in each compartment by means of a numerical method and the activity of Cs-137 was considered as an input of compartmental equations. We obtained the transfer coefficients between fish tissues by comparing the radiation curves with the actual data. In the light of the differences with the transfer coefficients, the calculation by the COMKAT software was found to be about 2%. Then, we provided the activity curves of Cs-137 and their characteristics (feature extractions) by changing the transfer coefficients and they were utilized to train the neural network. The network was trained for six data groups, and the results of the network testing had about 99% correct response, therefore it can be employed to estimate the transfer coefficients in fish tissue, the salinity range, and the activity of Cs-137 in water.

[en] Zirconium molybdate gel has an excellent characteristic to be used as a column matrix material of ⁹⁹Tc generators. The preparation conditions of zirconium molybdate gels will directly influence their physico-chemical characteristics and thus generator performances. In this work a series of zirconium molybdate gels were synthesized under different conditions and characterized by inductively coupled plasma, thermo gravimetric analysis , XRD and scanning electron microscopy Techniques. The effects of different parameters including p H of molybdate solution, Zr:Mo molar ratios, order of reactants addition, washing and granulating of gel on the performance of technetium-99m generators were evaluated. The experiments show that the optimum conditions for synthesis of the gel consist of: p H=4-4.5, Zr:Mo ratio of 1:1, gradual addition of molybdate solution to zirconium oxy chloride solution, no washing and grinding the resulted gel.

[en] Finite element and Monte Carlo are two basic and useful methods in numerous modeling and simulation codes. Charged particles transport in electric and magnetic fields based on these methods is the feasible manipulation of some software. There are, however few codes that have the ability of explaining the secondary radiation transport resulting from the movement of the charged particles in a magnetic field. FLUKA, for example, is known to be one of them. In this paper, a modeling and the simulation process using the FLUKA code for the survey of the synchrotron radiation of the electron are presented. The results found to be in agreement with those predicted by the known theoretical approach. The analysis of the synchrotron radiation of the output photon beam and the beam energy reduction are the basic results of the present work. For this investigation a specific field card MAGFLD and a USRBIN card have been applied.

[en] The fresh fuel for Bushehr Nuclear Power Plant-1 is due to be transported inside special containers which are supposed to be designed to stand against vibrations and impacts in order to protect the fuel from any possible damage. In order to perform die structural dynamic analysis of the containers, while being subjected to impact of dynamic forces, it is necessary to perform the vibration analysis which will lead to the vibrational modes and their natural frequencies for the structure of the containers. The vibration opposition of the containers must be far beyond the critical resonance. The resonance frequencies about the natural frequency of the structure will cause the enhancement of the oscillation range and may be ended with its disintegration. Determination of the natural frequencies and their mode shapes can be achieved by vibration-analyzing-methods. The amount of the natural frequency of any structure depends strongly on its shape, material and its lean points, as well as the amount and the type of the loads which the structure will be subjected to. In the present research, the container of the fresh fuel of Bushehr Nuclear Power Plant-1 is simulated by ANSYS^R10.0 and their ten natural frequency modes have been calculated

[en] :Quadrupole ion trap is widely used as an ion storage in gaseous phase and as mass spectrometer. In its classical approach, a sinusoidal voltage form is used to confine the ions in a small region. By using an impulsional voltage, on the other hand, it is possible to increase the mass spectrometer resolution so as to be applicable for separation of light isotopes. In this article we present the theoretical treatment based on the first and second ion stability region. The results show that the first stability region is more adaptable to the impulsional mode of ion trap operation

[en] The decay heat from radioactive waste that is to be disposed in the once proposed geologic repository at Yucca Mountain (YM) will significantly influence the moisture conditions in the fractured rock near emplacement tunnels (drifts). Additionally, large-scale convective cells will form in the open-air drifts and will serve as an important mechanism for the transport of vaporized pore water from the fractured rock in the drift center to the drift end. Such convective processes would also impact drift seepage, as evaporation could reduce the build up of liquid water at the tunnel wall. Characterizing and understanding these liquid water and vapor transport processes is critical for evaluating the performance of the repository, in terms of water-induced canister corrosion and subsequent radionuclide containment. To study such processes, we previously developed and applied an enhanced version of TOUGH2 that solves for natural convection in the drift. We then used the results from this previous study as a time-dependent boundary condition in a high-resolution seepage model, allowing for a computationally efficient means for simulating these processes. The results from the seepage model show that cases with strong natural convection effects are expected to improve the performance of the repository, since smaller relative humidity values, with reduced local seepage, form a more desirable waste package environment.

[en] A coupled thermal-hydrologic-airflow model is developed, solving for the transport processes within a waste emplacement drift and the surrounding rockmass together at the proposed nuclear waste repository at Yucca Mountain. Natural, convective air flow as well as heat and mass transport in a representative emplacement drift during post-closure are explicitly simulated, using the MULTIFLUX model. The conjugate, thermal-hydrologic transport processes in the rockmass are solved with the TOUGH2 porous-media simulator in a coupled way to the in-drift processes. The new simulation results show that large-eddy turbulent flow, as opposed to small-eddy flow, dominate the drift air space for at least 5000 years following waste emplacement. The size of the largest, longitudinal eddy is equal to half of the drift length, providing a strong axial heat and moisture transport mechanism from the hot to the cold drift sections. The in-drift results are compared to those from simplified models using a surrogate, dispersive model with an equivalent dispersion coefficient for heat and moisture transport. Results from the explicit, convective velocity simulation model provide higher axial heat and moisture fluxes than those estimated from the previously published, simpler, equivalent-dispersion models, in addition to showing differences in temperature, humidity and condensation rate distributions along the drift length. A new dispersive model is also formulated, giving a time- and location-variable function that runs generally about ten times higher in value than the highest dispersion coefficient currently used in the Yucca Mountain Project as an estimate for the equivalent dispersion coefficient in the emplacement drift. The new dispersion coefficient variation, back-calculated from the convective model, can adequately describe the heat and mass transport processes in the emplacement drift example.

[en] In spite of chickpea's use in Iran and its ability of being replaced to adjust the shortage of protein in dietary habits, yield production is very low. One of the main reasons for chickpea's low yield production is its sensitiveness to some diseases, pest and environmental stresses. Genetic variation in chickpea is very low, because of its self pollination. In breeding programs, genetic variation plays an essential role so that the induction of genetic variation in plant population is very important for the plant breeders. The induced mutation through different kinds of mutagens is one of the important ways of genetic variation. In this research, first the sensitiveness of four cultivars (ILC.486, Philip86, Bivinich, Jam) were assessed to different gamma ray doses (100, 200, 300, 400 Gy). The results showed that with an increase in gamma ray dose, the growth rate of chickpea's genotypes decreases. In this respect, the decrease of growth rate has a linear relationship with the gamma ray dose and it is independent from the genotypes. The root length is more sensitive to gamma ray doses than its shoot, and it was observed that at the low doses the root growth decreases, comparing to the shoot growth. On the other hand, in high doses of gamma ray growth abrasion (Ageotropism, Albinism and etc.) were observed. Some traits variation (such as leaf shape, leaf size, leaf color, Albinism, etc.) were seen in M₂ generation, and finally to continue the project, three doses of gamma ray (150,200,250) were selected for the next year