مجله علوم و فنون هسته ای
سال چهل و سوم شماره 2 (پیاپی 100، تابستان 1401)

This study uses real data of Bushehr nuclear power plant (BNPP), and by soft computing methods and without using the data of self-powered neutron detectors (SPNDs), the maximum linear heat rate of BNPP is estimated. The efficient learning algorithms of artificial neural network (ANN), including Levenberg-Marquardt (LM) and Bayesian regularization (BR) in combination with different features selection techniques including Pearson, Spearman, and Kendall’s tau, are employed to estimate the target parameter. Results show that the proposed method is appropriate for estimating the maximum linear heat rate. Given the importance of this parameter in terms of safety and the fact that its excessive increase actuates the shutdown signal of the reactor, the use of the appropriated approaches such as the present study can increase the safety of the plant and improve Defense-In-Depth (DID).

In proton therapy, as a prominent method for treating tumors, investigation of transport of the protons in the matter, which is a result of three main interactions of stopping, scattering, and nonelastic nuclear interactions, is highly important. In addition to the experimental method Monte Carlo simulations and the analytical process. There are sufficiently accurate physical beam models in the analytical approach to approximate the depth-dose distribution. However, this study involves challenges in the presence of localized inhomogeneities, which are unavoidable in body tissues. Investigating the behavior of protons in such a medium is vital to investigate three factors, including scattering, energy distribution, and fluence reduction in the boundaries. The present study deals with the scattering of protons in the slabs of different lengths and materials using the Fermi-Eyges theory. The results showed that the material composition also has a key effect on the scattering of protons in addition to the depth of penetration. The studies on the arrangement of layers and the effect of energy on the scattering showed that the arrangement of materials in the beam path has no significant effect on the final result. The scattering decreases with increasing the energy of the incident beam. It was found that the results are confirmed with the expected physics of the solved problems. To validate the results, the maximum scattering angle of the analytical method was compared with those of to the simulation using the MCNPX Monte Carlo code.

Recently, research has shown that PIN photodiodes can be used in ionization radiation detection, especially in medical applications. In this research, three photodiode-based X-ray detectors have been implemented. The preamplifiers in these circuits have completely different structures; the number of pulse shaper stages and the bias of photodiodes are different. The first circuit benefits lower manufacturing costs due to its simple structure. The second circuit has a preamplifier with feedback impedance that generates pulses with a large amplitude. The third circuit has better noise than the second circuit due to the transistor preamplifier structure with a small feedback capacitor, and its gain is larger than the first circuit. The S1223-01 photodiode from Hamamatsu Corporation has been utilized in the experiments, which is excited using the 232Th. Comparing the conversion gain, dissipation power, and pulse period of these circuits, the second circuit with a gain of 66.75-dB can be claimed to have the largest amplitude. Also, the first circuit with a noise power of 1.215-nV2 and a dissipation power of 36.6-mW, has recorded the lowest noise and energy consumption among others. The third circuit with a time period of 8.2-μs has the lowest pulse duration and dead time.

Thespot-scan based methods are expected to perform better than other methods for proton therapy in delivering the dose to the intended target. In this study, the GATE computer code is used to evaluate important dosimetric quantities in proton therapy, such as Full width at half maximum, peak position, range and peak-to-entrance dose ratio (percentage depth dose) in the proton therapy process under the same conditions based on spot scanning and passive scattering. Water phantom was selected and system energy parameters were measured using a set of depth-dose curve in the energy range of 120 to 235 MeV. Bragg peaks were generated with an accuracy of 0.7 mm in range. Spread out Bragg-peak were produced with 7 cm modulation and 10 mm range accuracy and peak-to-entrance dose ratio difference at an input dose of 8%. To evaluate the versatility of the beam, the Full width at half-maximum was evaluated with a maximum difference of 7% between the two methods. As a result, based on the simulations performed for different beam delivery systems, the ability of the spot scanning method in adapting to the target volume, better control over dose distribution and less extra-tumor dose was demonstrated.

By replacing hydrogen with deuterium in water molecules, the energy level of molecular bonds changes which cause different physical, chemical, nuclear, and biological properties. Owing to that, the Equation of State (EOS) is an important and appropriate tool for studying the thermophysical behavior of materials and predicting them in different conditions in terms of pressure, temperature, and volume. Due to the importance of heavy water and its role in various researches, especially nuclear research and its application in medicine and industry, the present work aims to calculate the fugacity and virial coefficients of this material using the new generalized state equations and to compare the results obtained with experimental data to have an accurate evaluation of the equations used. The generalized equations in this research include the generalization of the equations based on the Redlich-Kwong equation (RK) and the Dietrici equation (D). The studies showed that generalization improves the results of the second virial coefficient below the critical temperature, which is more effective in the RK equation and leads to appropriate results according to the experimental data. However, in the case of fugacity, generalization improves the results in Equation D and further deviates the results in the RK equation. The results show that below the critical temperature, the van der Waals and Dietrici models do not offer a good prediction of the behavior of the third virial coefficient. Therefore, more other models should be used to predict their behavior quantitatively and qualitatively.

Gamma ray measurement in various research fields requires high efficient detectors. In photon dosimetry, NaI(Tl) scintillation detector as one of the inorganic scintillation detector is noticeable, due to have the high amount of light output. In this study, the basics determination of photon dosimetry for the NaI(Tl) scintillation detector utilizing the Monte Carlo code (MCNPX) and using different methods of dose calculation (tally F6, * F4, + F6 and * F8) is studied. Regularly, the output of a radiation detector (counting the number of pulses) cannot be used to determine the radiation dose value. Therefore, in this study the spectro-dosimetry method based on software method is used to find out the value of the conversion coefficients to convert the detector spectrum to the value of air karma. In this method, the radiation dosimetry response is obtained with use of the MCNPX code simulation. The response function of the NaI(Tl) 3"×3" scintillation detector for several specific gamma rays was determined and then the functions of energy dependent conversion coefficients for calculating the dose values were obtained. Finally, with comparison of the measured data and simulation calculations results it is shown that the proposed method has a high accuracy in photon dosimetry

In this paper, the Hamiltonian of Bohr-Mottelson model was solved to determine the energy levels and also energy surfaces of 190Hg nucleus in the Z(5) critical point. The Morse and Harmonic oscillator potentials are used for radial and angular parts of Hamiltonian, respectively. The asymptotic iteration method is used to solve radial equation and the constants of model are extracted in comparison with experimental data. The results are compared with the predictions of previous studies which solved Bohr-Hamiltonian in this critical point with using infinite well potential for radial part and also the predictions of O(6) dynamical limit of interacting boson model. Significant improvements are yield with using Morse potential in determination of energy levels of excited energy bands. Also, the results of this potential show more corresponding with the predictions of O(6) dynamical model.

In this research, utilization of typical moisture separation process in conventional steam cycle power plants, for NPPs are recommended; and by applying CFD, two-phase flow of this process is simulated. Results show that with increasing of loading, the pressure drop across the separator increases, and a linear relationship between pressure drop and inlet flow kinetic energy density is established. Also, with increasing inlet width, pressure drop decreases and the efficiency increases. However, excessive increasing of input width leads to a decrease in mass flow at lateral outputs. Study on the variation of lateral outlet diameter show that variation of mentioned parameter does not affect pressure drop and efficiency significantly, but reducing of that lead to increasing lateral out let steam mass fraction. Based on the performed assessment, horizontal steam separator as a component with desirable efficiency and pressure drop, can be recognized as a suitable option for utilization in small and low power NPPs as well as propulsion systems. For validation, an analysis of two phase flow in a vertical cylinder cyclone is performed and results show good agreement with experimental data.

The Chahgaz iron deposit (XIV Anomaly) is located in the Bafq mining district in the Central Iranian geostructural zone in Yazd province. The Chahgaz deposit is hosted by Early Cambrian subvolcanic and volcanic rocks that range compositionally from granite to diorite. The field gamma spectrometry, mineralogical and geochemical studies in this deposit indicate that the thorium mineralization is mainly associated with Na-Ca and Mg- alterations, and in minor amount with the magnetite ore. The mineralogical studies by optical and electron microscope (SEM and EPMA) indicate that the main thorium host mineral in the Chahgaz deposit is thorite associated with minor titanite, allanite and zircon. The average contents of Th and ΣREE in the Th-mineralization zone are 450 and 596 ppm, respectively. Thorite is paragenesis with albite, actinolite, tremolite and augite in the Na-Ca alteration zone, and with talc in the Mg- alteration zone. In the Th-bearing iron ore, thorite is paragenesis with magnetite, calcite and apatite mineral assemblage. The similarity in mantle-normalized REE patterns of host rocks and thorium mineralization zone suggests that Th-mineralization is related to Early Cambrian calc-alkaline magmatism in continental-margin arc setting. The occurrence of paragenetic magnetite with thorite and distinct negative Eu anomaly in the thorium mineralization zone can be inferred probably a reduced condition for thorium mineralizing fluids.

In this study, the extraction of dysprosium was investigated using a supported liquid membrane (SLM) system. The experiments were performed using bis (2, 4, and 4-trimethylpentyl) phosphinic acid (Cyanex272) as the carrier. The effect of various parameters such as stirrer speed, feed phase pH, extractant concentration, initial metal concentration and membrane pore size on dysprosium transfer was studied. The highest membrane permeability was obtained with Cyanex272 at concentration of0.6 M and initial pH of the feed phase equal to 5 and stripping phase concentration of 1 M. Under optimal conditions, the membrane permeability of 2.15×10-5 m s-1 was obtained. Examination of SLM stability showed that the membrane used was stable for 6 periods (3 days) and permeability did not change significantly

Polymeric absorbers used in solar thermal collectors must have appropriate thermal and mechanical properties. In this work, polyethylene/graphite (PE/NG) nanocomposite was selected as polymeric absorber and the effect of radiation on the thermal and mechanical behavior of that has been investigated. PE/NG composites containing 0.05, 0.1 and 2.25% nanographite was prepared through melt extrusion process. The SEM images of the samples proved the fair dispersion of NG in polymer matrix. Then the samples were irradiated by electron beam at doses ranging from 100 to 200 kGy. The specimens were characterized by tensile testing, Differential Scanning Calorimetry (DSC) and FT-IR spectroscopy. The results show that nanocomposite containing 2.25% graphite irradiated at 100 kGy has the best tensile strength and thermal stability. The results of DSC show that the addition of 2.25% NG to polyethylene improves the melting point and thermal properties. DSC and carbonyl index results of this composite in accelerated aging condition display no remarkable changes occur in thermal performance and structure of composite during aging. Also, with addition of NG to PE the UV/Vis absorbance of the PE/NG nanocomposite increases. Altogether, the experimental results reveal PE/NG as suitable candidates for solar thermal absorbers.

In This study, an absorbent consisting of DEHPA impregnated onto Amberlite XAD-7 resin was prepared and used for the adsorption of Ce (ΙΙΙ) and La(ΙΙΙ) ions from aqueous solution. The absorbent (XAD-7 + DEHPA) was charaterized by SEM and FTIR analysis Techniques. Several influential variables such as, contact time, pH and  temperature were studied in batch mode of operation. Th results showed that the optimum adsorption condition  were acjieved at pH=6, optimum amount of absorbent and the equilibrium time equal to 0.6 gr and 180 min, respectively. According to the results the adsorption percentage of cerium and lanthanum ions onto the aforementioned resin were 99.99%, 78.76% respectively. Various isotherms models such as Langmuir, Freundlich, Temkin and Dubinin-Radushkevich were used in 25°C to analyze the equilibrium isotherm data and results showed that  Langmuir model had a better agreement with the experimental data. The maximum adsorption capacity of the resin  for cerium and Lanthanum ions were 8.28 mg.g-1, 5.52 mg.g-1 respectively. The kinetic data were fitted to pesudo- frist- order, pesudo-second-order and Intra particle diffusion models. Based on the results, the pesudo- frist- order model and Intra particle diffusion  model described the experimental data as well. Thermodynamic parameters of adsorption such as ΔHº, ΔS°, ΔG° were calcutated. Positive ΔHº and negative ΔG° were indicative of the endothermic and spontaneous nature of the adsorption. The  aforementioned resin shows the stability during the five cycles of adsorption-desorption and it’s  degradation was less than 3%

The purpose of this paper is to investigate the possibility of using tubular fuel assemblies in Tehran Research Reactor (TRR) from the thermal hydraulic perspective. Tubular fuels have been used successfully in many Russian model research reactors in recent decades. The most important advantages of this fuel are higher neutron flux, more reactivity and less fuel loading compared to the current plate fuels. In this study, by selecting a tubular fuel assembly of IRT-4M type that is more geometrically compatible with the geometry and dimensions of the core grid plate, we modeled it using the Fluent software and also the RELAP5/Mod3.2 code. The thermal hydraulic parameters of this assembly have been calculated under the operating conditions of current MTR fuel. The results of the calculations showed that the maximum clad temperature in both calculation tools is sufficiently lower than 105°C, which indicates that without changing the current flow rate of the core, the heat produced in the tubular fuel can be well removed. Moreover, the maximum fuel temperature in tubular fuel is about 10°C lower than the maximum fuel temperature in the current standard fuel element, which is another advantage for this fuel type.

Nowadays, due to the threats of radioactive materials, control of border and sensitive facilities is of particular importance. For this reason, every year the International Atomic Energy Agency publish a report on the theft, loss or lack of monitoring and control on the movement of the radioactive materials in some countries. Therefore, introducing new methods to deal with such threats is essential. One of the most effective systems for detecting radioactive materials and contaminants are radioactive portal monitors. In this study, the results of performance evaluation of large plastic scintillation detectors for use in this type of monitoring systems are presented. Initially, the design and construction of detection circuits, electronic and mechanical holders were done. Then, the functional tests of the device were performed using 60Co and 137Cs sources. Finally, the minimum detectable activity using this monitoring device was determined. The results of the tests to determine the minimum detectable activity of the system showed that it can detect a 60Co source with a minimum activity of 1 µCi at a maximum distance of 100 cm and a 137Cs source with a minimum activity of 2 µCi at a maximum distance of 75 cm. Regard to the obtained results, it was found that the developed monitoring system has the ability to detect the radioactive sources with good accuracy.

In this paper, Yrast spectrum and the ratio of the electromagnetic reduced transition probability, B(M1)/B(E2) has been calculated up to the spins 47/2+,33/2+ and 31/2+ for 185-187-189Os isotopes using projected shell model, respectively. In the B(M1)/B(E2) ratio were observed great drops in spins 39/2+, 33/2+ and 29/2+ that corresponds to decreases the nuclear rotation that can be the reason of band crossing of three quasi-particles with single-particle neutron band in yrast spectra. Finally, in general, it is observed that with increasing number of nucleons, the trend of increasing the ratio of electromagnetic transitions is the and for the second one only for 189Os isotope after spin 39/2+, rotation and magnetic properties of nucleus increases.

Induction of Gynogenesis in sturgeon is important, therefore, the aim of this study was gynogenesis inducing in Ship sturgeon Acipenser nudiventris by gamma radiation to the heterologous sperm of Persian sturgeon Acipenser persicus. At first, sperm was extracted, and in the next stage, irradiation was performed with doses of 0.45, 0.6, 0.75, 0.9 and 1.05 kGy. Then oocytes were obtained from fish and fertilized by different dosages of irradiated sperms and cold shock was used to ploidy inducing. Control group (fertilization of normal sperm and oocytes), hybrid (fertilization of normal Persian sturgeon sperm and ship sturgeon oocytes), haploid (fertilization of irradiated sperm and normal ship oocytes), and triploid (fertilization of ship sperm and oocytes with cold temperature shock) were considered. The fertilized eggs were transferred to the incubator until hatching and the percentage of fertilization and hatching was calculated after the evolutionary period in the incubation. DNA was extracted from different group’s larvae and the success rate of inoculation was determined using Afu9 and Afu68 microsatellite markers. The results showed that the 0.9 kGy group had a higher rate of fertilization and hatching (P <0.05). Inheritance assessment showed that gynogenesis was performed successfully in different groups. It can be concluded that gynogenesis in this fish has been done successfully and due to the higher efficiency, 0.9 kGy dose, it was recommended for this species gynogenesis.

The risk assessment of local nuclear fuel melting in nuclear power plants (NPPs) due to its localized nature and the difficulty in accurate monitoring is of vital importance for safe operation of nuclear reactors. Experiences have shown that flow blockage accident without safety control rod axe man (SCRAM) can lead to local nuclear fuel melting which consequently affect the safety of NPPs. The purpose of this study is to analyze the transient states leading to local fuel melting based on ATWS-related events given in FSAR of the VVER-1000/V446 nuclear reactor including pump failure, local blockage, power level increasing and their combinations. In this work, a coupling framework is first developed based on the MCNPx and the COBRA/EN codes. After validation with available data, the results showed that despite 18% deviation from the mass flow rate reduction limitation, 470 kPa from the channel pressure drop limitation, and 204K from the clad temperature limitation in the most pessimistic situation, the reactor SCRAM does not occur. However, in these conditions (where SCRAM does not occur), 70% void fraction for 12 minitues is observed in some channels. Therefore, there may be dry spots and local melting of fuel in normal operational and ATWS conditions that need to be identified. According to the results, the occurrence of the void fraction above zero is locally expectant and an appropriate monitoring system should be used to identify weakness points of the system.

In this paper, the effect of cold plasma treatment on the removal of amoxicillin from its aqueous solution is investigated. First, the atmospheric cold plasma system made based on the dielectric barrier discharge.  The geometry of this system is cylindrical and air plasma generates with AC electrical discharge at atmospheric pressure. The treatment was performed in such a way that the liquid was flowed in a thin layer on the surface of the internal electrode of the plasma reactor and was subjected to plasma at different times from 5 to 120 minutes. Hear, for experiments, 3 liters of amoxicillin solution with an initial concentration of 100 mg/lit was used. Then, the aeration effect was investigated by simultaneous injection of oxygen gas. In this work, the analysis was performed using HPLC. The results showed that after 120 minutes of treatment, the concentration of amoxicillin decreased by about 88% and the synergy of oxygen gas improved the degradation process by about 13%. Therefore, high-energy electrons and oxidizing species produced in the cold plasma system can well degrade amoxicillin. It is predicted that with this method, water can be free of medicinal compounds, without the need to use chemicals or filtration.

In this article, the behavior of a short pulse, pre-ionized flashlamp for pumping the laser-induced plasma has been experimentally studied. The total discharged energy is nearly 2 joules to generate 1 microsecond optical pulses. For this means, an especially designed discharge circuit with a single high voltage switch where consists of three trigatron switches in series was implemented. The observations show that the flashlamp doesn’t obey the classical Goncz’s V-I characteristics with a constant  under experimental conditions. The flashlamp behavior can be more suitably described with a Freundlich’s equation. Moreover, the parameter is a function of the discharge current with a different behavior on the leading and falling edges of the current pulse. The shortest flashlamp optical pulses were achieved with about 5 microseconds delay time among the pre-ionization and the main discharge of flashlamp.

In the enrichment industry, it is very important to study the transport coefficients such as thermal conductivity, viscosity and diffusion coefficients of isotope gases such as xenon, tellurium hexafluoride and uranium hexafluoride. In general, there are two perspectives for studying the behavior of gas: the macroscopic and the microscopic perspective. The macroscopic model considers the behavior of a gas as continuous and the microscopic model, considers the gas as separate particles and for each particle, a position and velocity at a specific time. In this paper, the thermal conductivity, viscosity and diffusion coefficients of single-component, binary mixture, multicomponent and isotopic gases are investigated using the microscopic properties of gases. Then the values of these coefficients are determined for all isotopes of xenon, tellurium hexafluoride and uranium hexafluoride. The COT POD software has also been prepared by these relationships extracted for transport coefficients. Due to the lack of experimental results for isotopic validation, the results of microscopic relationships obtained from the software are compared with the experimental results of a mixture of different gases including helium and neon and then neon, argon and krypton multi-component systems. Results have a good agreement with each other.