مجله علوم و فنون هسته ای
سال چهل و پنجم شماره 3 (پیاپی 109، پاییز 1402)

Heavy metal ions have increased wastewater production with the development of various nuclear activities. One of the most significant metal ions that harm the environment and living organisms, especially humans, is the uranyl ion. There are many methods to remove metal ions, and biological adsorption is the cheapest and most efficient method. In this research, the absorption of uranyl ions from aqueous solutions from tea waste has been studied. Due to the presence of various functional groups such as carboxyl, hydroxyl, amine, etc, tea wastes have good cations adsorption ability. The effective parameters in adsorption including pH, adsorbent dose, temperature, initial uranyl concentration, and contact time parameters were investigated. Response surface methodology (RSM) was used to conduct experiments and analyze the results. The optimum conditions for uranyl adsorption by tea waste adsorbent were pH = 3.9, temperature 25°C, adsorbent dose 0.275 g, initial concentration of uranyl 10 mg/L, and contact time 90 minutes. Using Freundlich's isothermal and pseudo-second-order models, we fitted the most accurate isothermal and kinetic models. Results showed that tea waste was a good bio adsorbent for uranyl adsorption from real wastewater with a 93.50% adsorption rate.

Xenon radioisotopes are one of the products of nuclear fission of uranium. These radioisotopes are released in the form of gas in the process of dissolving the uranium target to extract 99Mo. The aim of this research is to measure the activity of released xenon radioisotopes. For this, radioxenon is separated from other fission products using activated charcoal and purified after passing through a carbon molecular sieve. Pure radioxenon is directed into the measurement chamber and determined using HPGe detector. Calibration of the detector efficiency has been performed via using experimental and simulation (using MCNPX27e code) methods in which the difference was less than 22%. In this way, the average activity of 100 cc of radioxenon gas at the moment after the end of irradiation was equal to 54225 ±2272 Bq.

One of the important steps in the nuclear fuel cycle is uranium enrichment. It is essential to carry out control processes using continuous measurement on the way to uranium with the desired enrichment of the facility. On the other hand, due to being in the environment with high external radiation and also suitable for internal exposure of the operator, especially when working with uranium powder, it is necessary to use accurate instruments with the ability to monitor online and continuously, which is a special place in the nuclear instrumentation. In this work, we decided to work on a conceptual design of the enrichment and weight measurement system for uranium tetrafluoride powder into loading and handling tanks in the nuclear industry. For this purpose, with the aim of reducing costs while eliminating maximum counting error, focus on reading only gamma rays emitted from powder or with radioactive lateral source was considered. The design was based on geometric location optimization of scintillating detector/detectors around the tank containing uranium tetrafluoride powder in order to have maximum accuracy in measurement. The simulation results in Monte Carlo software show that for different enrichment percentages and also different heights of uranium powder inside the cylindrical tank, we are able to have maximum accuracy in measuring two parameters of richness percentage and powder weight at specific angles.

In this research, ultra violet (UV) photodetectors based on rather aligned ZnO nanorods thin film with controllable responsivity were fabricated. Aligned nanorods were grown on the seeded glass substrates by chemical bath method. Then, they were characterized using Scanning Electron Microscope (SEM), X-Ray Diffraction (XRD), photoluminescence (PL), and Energy Dispersive X-ray Analysis (EDAX). The effect of perimeter and area variation of interdigitated electrodes on the responsivity of UV ZnO nanorods-based photodetector was investigated. The responsivity shows a decreasing trend with decreasing electrode perimeter and keeping the area constant. By keeping the perimeter constant in the maximum value, it is observed that the response of the photodetector is increased with increasing the gap between the fingers of the electrode so that the gap of 160 µm reaches the maximum as high as 105 AW-1 at 2 V bias voltage. The dominant mechanism for change of the responsivity with electrode geometry is purposed on the basis of variation in the area of depletion regions resulting from Schottky barriers between ZnO and Au and the formed barriers between ZnO nanorods due to adsorption and desorption of oxygen species. This research demonstrates a simple way of optimizing the responsivity of photodetector devices for practical applications.

By applying two relativistic high intensity laser beams under different conditions on low density plasma, the effects of beams relative distance and angle on their filamentation were investigated and studied. The results of the simulations using the particle in cell (SMILEI) two-dimensional code show that when the distance and the relative angel between the pulses is zero, the results are the same as a powerful pulse with the intensity equals four times a single pulse. Meanwhile, it was clear that, the impact of relative beams angles on the pulse filamentaion is so important and sensible than the effect of distance variation. So that, it is shown than by increasing the distance, separate plasma channels formed and more filaments observed. Moreover, the effect of relative beams angles variation reveal that, at unexpectedly, wo distinct channel formed and traveled through plasma so that by increasing the angle to , the channels merge together and formed a single wide channel. Further, for a constant beams distance, the maximum filaments observed at the middle angles . It should be noted that studying laser beams filamentation in plasma is so important for stable pulse propagation through the plasma and our simulations indicate that in some relative angles we will not have stable and efficient pulse propagation which could be distractive in some experiment such as inertial confinement fusion.

By applying two relativistic high intensity laser beams under different conditions on low density plasma, the effects of beams relative distance and angle on their filamentation were investigated and studied. The results of the simulations using the particle in cell (SMILEI) two-dimensional code show that when the distance and the relative angel between the pulses is zero, the results are the same as a powerful pulse with the intensity equals four times a single pulse. Meanwhile, it was clear that, the impact of relative beams angles on the pulse filamentaion is so important and sensible than the effect of distance variation. So that, it is shown than by increasing the distance, separate plasma channels formed and more filaments observed. Moreover, the effect of relative beams angles variation reveal that, at unexpectedly, wo distinct channel formed and traveled through plasma so that by increasing the angle to , the channels merge together and formed a single wide channel. Further, for a constant beams distance, the maximum filaments observed at the middle angles . It should be noted that studying laser beams filamentation in plasma is so important for stable pulse propagation through the plasma and our simulations indicate that in some relative angles we will not have stable and efficient pulse propagation which could be distractive in some experiment such as inertial confinement fusion.

We are studying the experimental behavior of non-refractory and refractory wires in the 1 kJ pulsed electrical system. This article discusses the experimental study of the behavior of non-refractory (copper-nickel) and refractory (tungsten) explosive wires in pulsed electric discharge systems. The energy of the system is 1 kJ, the length of the wire is 4 cm, and its diameter is 200 μm. In order to study the behavior of the wires, the electrical parameters of current and voltage of electric discharge and shock wave have been investigated. In non-refractory wires, the current is established periodically and has two peaks. In refractory wires, two current peaks are formed at a longer time interval, which shows that the energy level of 1 kJ was not enough to change the state and create plasma in this sample of wires. Finally, with the current test conditions and comparison of the experimental results, it can be seen that the non-refractory wires create a more substantial shock wave than the refractory samples. This pressure is 8.5 MPa in non-refractory wire (copper-nickel) and 6 MPa in refractory wire (tungsten). Also, we compared the electrical discharge current for three copper-nickel wires with diameters of 100, 200, and 300 micrometers and experimentally observed that the electrical discharge current is higher in the wire with a thicker diameter.

One of the frequently observed random processes in nuclear experiments, is the Poisson process. Due to the dead time effect of the detection systems, the experimental process is different from the Poisson process. In this work, based on stochastic methods, a nuclear detection system is identified. One of typical pulse mode detectors is BF3 detector. In this research, a typical BF3 detector is selected to implement the above method, and then observed pulses at the output of the detector in the time domain were measured and analyzed using the stochastic analysis of fluctuations. In experiments such as measurements related to the zero-power reactor noise theory, the transfer function of the detection system itself also has an effect on the obtained results. Therefore, knowledge of the transfer function of the detection system used in these experiments is of particular importance. Also, in the measurements where it is necessary to correct the dead time of the detection system, the specificity of the transfer function can provide useful information about the effects of the dead time. In this research, the transfer function of a typical neutron detection system based on BF3 detector has been investigated.

For the neutronic and thermal-hydraulic analysis of nuclear reactors core, it is necessary to develop nuclear computing softwares in order to calculate the neutronic and thermal-hydraulic parameters for the safe operation of them. In this paper, S4HC software was developed for steady-state thermal-hydraulic core calculations using single heated channel method. In order to analyze the core of Bushehr reactor, after calculating neutron parameters by nodal expansion method, thermal-hydraulic analysis of fuel assemblies was performed using S4HC software. After thermal-hydraulic calculations for the fuel assemblies, including the hot fuel assembly, it was concluded that all the thermal-hydraulic parameters of the coolant are within their allowed ranges and the reactor has a good saturation margin.

The product of Molybdenum-99 purification process, obtained from the acid dissolution of Uranium-235 fission products, has a degree of purity of 90%-95%, which its present active and inactive impurities are destructive reducing the efficiency of 99mTc/99Mo generators. The use of indirect sublimation method as an excessive purification step could increase purity and reduce molybdenum lost instead of commonly sublimation method. In this method, the molybdenum in product will be absorbed by passing through the column containing alumina and then the dried absorbent will be sublimated. In the present study, the effective factors in molybdenum absorption such as the amount of adsorbent, the volume and flow rate of the input solution and molybdenum were optimized. The finally absorption efficiency reached 97-99%. This investigation is predicted for the production of molybdenum-99 in the industrial scale.

In this study, in order to produce and develop a new diagnostic radiopharmaceutical for the imaging of tumors overexpressed somatostatin receptor, [113mIn]In-DOTATATE labeled compound was prepared in optimal conditions using an in-house generator and its precilinical studies was performed. The final product was obtained with a radiochemical purity of nearly 99% (RTLC and HPLC) and a specific activity of 26.2×1015 Bq/mol. The investigation of the stability of the labeled compound showed a radiochemical purity of more than 96% for at least three hours in PBS buffer and in human blood serum.. The results of the biodistribution and the images assessment of the [113mIn]In-DOTATATE labeled compound in normal mice showed that the organs of the gastrointestinal tract such as the pancreas, stomach and intestine, which have cells expressing the somatostatin receptor, have high uptake.

60Co is used as an important industrial radioactive source in the sterilization of food and medical equipment. kCi sources can mainly be used for laboratory research, however, there are few industrial centers that use these sources for irradiating agricultural products. Hence, in this study, the potential of producing tens of kCi of 60Co sources in Tehran research reactor has been investigated using MCNPX code. Different assemblies including 59Co rods were modeled by computational code. In addition, the loading of the 59Co rod assembly in different arrangements of the Tehran research reactor core was investigated and the 59Co production yield was calculated in each of the modeled cases. The results of this study show that by optimizing the 59Co rod assembly in a 27-fuel 1401 year core arrangement of the Tehran Research Reactor, it is possible to achieve about 40 kCi of 60Co product after 3 years of irradiation. The use of beryllium reflector with optimized geometry can reduce the negative reactivity caused by the loading of 59Co assembly. Also, loading the cobalt-59 assembly in the periphery of the equilibrium core of the Tehran research reactor can lead to the production of about 23 kCi of cobalt-60.

In this study, the Monte Carlo based simulation code, Geant4, was used to model the 2-inch NE-213 detector and Am-Be source available in Sharif University Faculty of Energy and the neutron and gamma spectrum for this source in the NE-213 detector could be achieved. Furthermore, a circuit based on analogue Constant Fraction Method (CFM) was used in laboratory to get the neutron and gamma spectrum of the same source to be used for further comparisons. For next step, three digital filters named as Triangular, Trapezoidal and Flat Top Cusp were scripted in MATLAB not only to see how each filter performs in discrimination of these two spectrums, but also to find the optimum values for the effective parameters in each of the filters by comparing the filter outputs with the results obtained from constant fraction method in lab. As it appeared, in triangular filter for k=11, trapezoidal filter for k=10 and L=5 and in the flat top cusp filter for k=10 and L=20, best results were obtained. By comparing the results for these values in each filter, it was shown that the trapezoidal filter performed the best in spectrum discrimination.

In this research, the effect of simultaneous application of plasma rotation and static external magnetic field in a plasma with power law density function on the growth rate of Rayleigh-Taylor instability has been studied analytically. The plasma is assumed to be an incompressible and is enclosed between two planes z=0 and z=h. In a linear growth rate regime, the dispersion relation for the ideal MHD equations was first derived by applying the rotation effect and appropriate boundary conditions. The final dispersion relation represents the effect of the simultaneous combination of the axial magnetic field and the constant angular velocity of the plasma on the growth rate of Rayleigh-Taylor instability. The results show that the growth rate of the instability depends on the horizontal component of the magnetic field, the plasma rotation and also the dimensionless parameter λ*. The maximum instability occurs at the value of λ*=-1.5. Compared to the corresponding non-rotational case, recent results show that the simultaneous combination of rotation and static external magnetic field improves the management of the instability growth rate.

Saintpaulia ionantha is a beautiful ornamental plant. to induce diversity by creating new genotypes of African violet in vitro Gamma ray and EMS were applied as physical and chemical mutagens respectively. Explants were cultured in MS medium containing 2 mg L-1 BA, 1 mg L-1 NAA, 30g L-1 sucrose and 7g L-1 agar. after two days they were treated with radiation (0, 20 and 40Gy) or EMS (0, 0.1, 0.3 and 0.6%). the dose of 40Gy and 0.3% and 0.6% of EMS reduced the regeneration of explants, the number of regenerated plantlets and leaves and caused enhanced variation and morphological changes. the color of leaves, their shapes and sizes were modified. afterwards genetic diversity of the mutant plants was investigated with ISSR marker. Eight primer pairs in PCR amplified different fragments of the genomic DNAs. Overall, 71 locations (bands) were scored. The dendrogram of cluster analysis using Jaccard coefficient and UPGMA algorithm showed high variability. The mutants were divided into 4 groups in similarity of 0.51%. Genetic similarity coefficient varied between 0.45-0.98 and 6 mutants were introduced based on morphological and molecular variations. the results showed in vitro mutagenesis of African violet by gamma radiation a suitable strategy to increase diversity.

Cold atmospheric plasma technology has found wide applications in agriculture as a suitable alternative to traditional and environmentally friendly methods. In this research, the effect of RF plasma treatment on the germination characteristics of oilseed rape in response to drought stress has been investigated. This study was conducted as a factorial experiment based on completely randomized design in 1401. The plasma factor in seven levels (P1, P2, P3, P4, P5, P6 and P7) and the drought stress factor in three levels were -0.3, -0.5 and -0.9 MPa. The results showed that the drought stress levels of -0.5 and -0.9 MPa caused a significant decrease of 50.16 and 61.92% of root length, 8.42 and 71.57% of shoot length, 21.79 and 85.46% of root dry weight, 4.87% and 39.08% of stem dry weight, 16% and 24% of germination percentage compared to drought level -0.3 MPa. In this experiment, the longitudinal growth of the stem compared to the longitudinal growth of the root was more affected by severe drought. Therefore, it can be a suitable feature to evaluate tolerance to drought stress. Exposure of canola seeds to plasma treatments of 200 W for nine minutes showed the most stimulating effect regarding the percentage of germination and seedling growth in canola.

In this research, extraction of cobalt ions from non-aqueous medium was carried using Aliquat336 extractant. The effect of different parameters on the non-aqueous extraction process including ethylene glycol concentration, extractant concentration, hydrochloric acid concentration and cobalt ions concentration in aqueous solution was investigated using the experimental design approach. According to the desirability of one and the maximum extraction efficiency of cobalt ions, the optimal conditions include volume percentage of Aliquat336 (19.2%), cobalt concentration (899.4 ppm), volume percentage of ethylene glycol (65.3%) and hydrochloric acid concentration (7.81 M) were obtained. The validity of the data was observed with minimal error between the predicted data (94.82%) and the experimental data (99.36%).

Albumin particles are used in nuclear medicine as carriers of diagnostic and therapeutic radionuclides. For this purpose, these particles were prepared using temperature. After size determination, the particles were labeled with gamma irradiated radionuclide 99mTc in the presence of stannous chloride as a reducing agent. Radiochemical purity was determined by chromatography methods. For labeled particles, stability in normal saline and biodistribution in normal and glioma tumorized rat were determined. The size of particles was determined in the range below 50 nm. Radiochemical purity of more than 98% was obtained. Evaluation of labeled particles stability showed a radiochemical purity of more than 90% during 6 hr in saline and human serum solutions. The results of biodistribution studies determined liver and tumor uptake followed by high kidneys washout. Gamma imaging scintigraphy in rat, showed tumor and kidneys. The results confirmed the ability of labeled particles as a tumor diagnostic radiopharmaceutical.

In this research, the effects of high-energy proton bombardment produced by the plasma focus device on the surface morphology and structural parameters of tungsten and molybdenum were investigated. Tungsten and molybdenum samples, placed at a distance of 6 cm from the anode head, were irradiated with hydrogen ions in 20 discharges. The samples were examined before and after irradiation using a scanning electron microscope (SEM). The SEM results revealed the formation of blisters, cracks, and surface melting on both tungsten and molybdenum samples due to the high-energy proton irradiation. To characterize the ion beam of the plasma focus device, Lee's code was employed. The results from Lee's code indicated that approximately 7.9 × 1014 ions are emitted from the plasma column in each discharge. Additionally, the SRIM code was utilized to calculate the damage created in tungsten and molybdenum, as well as the hydrogen density at various depths within the materials. According to the SRIM code results, the maximum value of displacements per atom (dpa) per shot for tungsten and molybdenum samples irradiated with hydrogen ions was estimated to be 0.025 and 0.014, respectively, at depths of 150 nm and 250 nm. Moreover, the maximum concentration of hydrogen ions in the irradiated samples of tungsten and molybdenum at depths of 150 nm and 250 nm was found to be 0.4% and 0.035%, respectively.

A factorial experiment was conducted to determine the effects of different doses of gamma irradiation on postharvest life and quality of bulbs of four Iranian onion cultivars (White-Ghom, White-Neyshabour, Red-Ridge-Lump, Red-Ray-Corrugated) during 120 days storage at 10-15 °C and 70% relative humidity. Interactive effects of cultivar and irradiation dose significantly affected sprouting, weight loss, firmness, soluble solids content (TSS), and contents of reducing sugars and pyruvic acid (PA) of the bulbs after 120 days of storage. Sprouting of the bulbs ranged between 10-100%. The untreated bulbs represented the highest sprouting and weight loss. Gamma irradiation (30-150 Gy) significantly restricted sprouting percentage and consequently decreased weight loss of the bulbs. Firmness of the irradiated bulbs (90-150 Gy) was higher than the control bulbs. Weight loss of the bulbs was positively correlated with sprouting and it was negatively correlated with bulb firmness. The irradiation treatments increased TSS (30-150 Gy) and reducing sugar content (60-150 Gy) of the bulbs. The untreated bulbs had the lowest PA content at the end of the experiment. Exposure to 90-150 Gy irradiation doses resulted in the highest PA content in the bulbs. In summary, application of 90 to 120 Gy of gamma radiation for improving postharvest shelf life and quality of onions can be considered as a general guideline.

Nowadays, due to the need of all countries to provide sustainable energy, nuclear energy plays a significant role in the energy portfolio of developed countries as well as developing countries. For this reason, it is very important to choose the appropriate nuclear fuel cycles for the optimal use of nuclear energy and drawing the road map of the country's nuclear industry. ; which itself is a function of several parameters (the level of nuclear knowledge, sources and reserves of nuclear materials and economic factors, etc. They are factors that play a significant role in determining the appropriate cycle). In this research, four main scenarios have been proposed by comparing the types of uranium, plutonium, and thorium fuel cycles, as well as by examining the nuclear material capacity, and suitable and cautious fuel cycles have been introduced for each required nuclear fuel scenario and the amount of consumption. Among the proposed scenarios, the scenario of "accessing sufficient uranium resources and opening up the enrichment and reprocessing" was introduced as the most likely scenario and based on the proposed axes, the most suitable closed uranium fuel cycles, with a fast sodium reactor and uranium, TRU and FP fuel cycle” were selected" with a minimum of 2320 and a maximum of 5296 GW of energy production and total costs of approximately $117 million per GW of energy.