Abstract This paper presents the design of an artificial neural network (ANN) to identify the In-Core Loose Parts in the Instrumentation Position (ILOPAIP) in the Bushehr nuclear reactor. Initially, a neutron noise simulator generates the outputs for the 54 neutron detectors in the reactor core due to ILOPAIP. These outputs are then used to design and train a multilayer perceptron. The neutron noise source caused by ILOPAIP comprises two components: an absorber of variable strength type. Therefore, the first step involves determining the location of the neutron noise source of the absorber type with variable strength. An ANN with a hidden layer is designed to identify the location of this neutron noise source. The results show a deviation of about 1% from the desired output values. Subsequently, the location of ILOPAIP is identified using an ANN with two hidden layers. The results show a deviation of about 3% from the desired output values. Overall, the findings indicate that due to the complex relationship and the dependence of neutron noise on the location of the detectors, the use of ANN is effective for this identification.

Abstract This study investigates uranium recovery from a chloride medium using a bulk liquid membrane containing the crown ether DB18C6. The effects of pH and chloride concentration in the donor phase, diluent type and carrier concentration in the liquid membrane phase, and the type and concentration of the acceptor phase, along with transport kinetics, were examined. Results indicated that increasing the crown ether concentration in the liquid membrane phase initially enhanced ion transfer. However, beyond a certain point, further increases in crown ether concentration reduced ion transfer due to increased viscosity. While diluents alone could not transfer ions, the type of diluent influenced the transfer process. Optimal uranyl ion transfer was achieved with a donor phase containing 2 M potassium chloride at pH 4. The type and concentration of the mineral acid in the acceptor phase significantly affected the transfer efficiency, with 0.1 M hydrochloric acid facilitating the maximum transfer of uranyl ions. The study of transfer kinetics revealed that the rate-controlling step is the release of uranyl ions from the liquid membrane into the acceptor phase. Under optimal conditions, selective transfer of uranyl ions was achieved in the presence of molybdenum, niobium, titanium, vanadium, and tungsten. The uranium transfer rate from the donor to the receiving phase exceeded 91%.

Abstract Dynamic Positron Emission Tomography (PET) imaging has significant potential for extracting kinetic parameters of tracers, particularly the Ki parameter. This study evaluates the use of the Dual Time Point (DTP) technique to generate parametric Ki images from two 3-minute static PET scans. A simulation study was conducted using the XCAT phantom, generating six realistic heterogeneous tumors embedded in lung and liver tissues with various levels of [18F] FDG uptake. Parametric Ki images were generated and evaluated using Patlak analysis and a population-based input function (PBIF). Additionally, TBR and CNR parameters in SUV images and parametric images produced by DTP and full dynamic methods were compared and analyzed. The results showed a significant correlation (> 0.9) between the Ki parameter derived from DTP and full dynamic imaging methods. Moreover, the high TBR parameter in DTP images compared to SUV images (70% for lung tumors, 35% for liver tumors) indicates improved contrast and image quality. Consequently, DTP images can be a suitable alternative to complete dynamic PET and SUV images in clinical settings.

Abstract This research evaluates the hydrodynamic behavior of a packed-agitated column, which includes agitated and irregularly packed sections, for extracting thorium ions from an aqueous solution. The effects of various operating parameters on the column's hydrodynamic conditions were investigated. Results indicate that increasing operating parameters such as agitation speed, dispersed phase velocity, and continuous phase velocity enhances thorium extraction efficiency. The maximum extraction efficiency achieved was 97.54% at an agitation speed of 220 rpm, with dispersed and continuous phase velocities of 0.66 mm/s. Increasing the agitation speed results in smaller droplet sizes and a narrower droplet size distribution. Additionally, an increase in continuous phase velocity, while keeping other parameters constant, creates resistance to the movement of dispersed phase droplets, leading to a decrease in slip velocity.

Abstract Propelling transport means using nuclear energy (nuclear propulsion) is a significant application of this energy. Currently, only nuclear-weapon states possess and operate nuclear propulsion systems. However, some non-nuclear-weapon states are also attempting to acquire this technology. This article investigates and evaluates whether international rules permit non-nuclear-weapon states to operate nuclear propulsion systems using a descriptive-analytical approach. The findings indicate that, under current international rules and subject to certain requirements, non-nuclear-weapon states are allowed to obtain or operate nuclear propulsion systems. Nevertheless, the legal framework governing nuclear propulsion in non-nuclear-weapon states is marked by inadequacies, ambiguities, and challenges that may impose practical restrictions on their ability to acquire and operate such technology.

Abstract In studying the interaction of hydrogen ions emitted from a plasma focus device with selected materials for the first wall of a tokamak, characterizing the ion beam is crucial. For this purpose, a Faraday-cup detector was designed and built for the MTPF plasma focus device, and its electrical parameters were extracted. The signals obtained from the Faraday-cup exhibited two peaks: the first peak corresponds to radiation impact, and the second peak is due to the impact of the hydrogen ion beam on the graphite electrode of the Faraday-cup. Using the time-of-flight (TOF) method, the average energy of the hydrogen ion beam was determined to be 46 keV. The flux parameters of the beam at the aperture of the Faraday-cup were 2.37×10^24 ions.m^-2.s^-1 and 1.45×10^16 ions.m^-2, respectively. The specifications of the MTPF plasma focus device were incorporated into the Lee model code, and the resulting ion beam specifications from the code showed good agreement with the experimental results obtained from the Faraday-cup signal. Additionally, other characteristics of the hydrogen ion beam were extracted.

Abstract Inertial electrostatic confinement fusion (IECF) devices are utilized for studying nuclear fusion reactions, particularly for fusion neutron production. A strong electric field between two transparent electrodes results in the formation and acceleration of ions toward the device's center. The energy level of these accelerated ions reaches tens of kilo-electron volts, sufficient to produce fast neutrons through nuclear fusion reactions when deuterium gas is used. Overheating due to collisions of high-energy ions with the cathode surface is a primary issue that limits the applied power and long-term stable operation of these devices. In this research, an actively cooled cathode was designed and constructed for the IR-IECF device. Deionized recirculating water was used as the coolant to reduce the cathode temperature. The cathode, connected to a high voltage power supply via a feedthrough, can prevent high voltage breakdown and melting at input powers exceeding three kilowatts. Both theoretical and experimental results show excellent agreement in heat removal during continuous operation.

Abstract This research investigates and optimizes the parameters of solvent extraction processes using thorium leach solutions from Chahgaz ore with D2EHPA. The effective parameters in the solvent extraction process were evaluated through experimental design to maximize thorium extraction and minimize iron extraction. Under optimum conditions—pH 0.6, extraction time of 2 minutes, 16% solvent concentration, and an organic-to-aqueous phase ratio of 1:2—thorium and iron recoveries were 99.47% and 9.60%, respectively. For the optimization of the stripping process, 89.75% thorium and 0.6% iron were recovered in 3.34 minutes with an organic-to-aqueous phase ratio of 2:1 and a sulfuric acid concentration of 3.9M.

Abstract This study proposes a design, based on theoretical calculations, to increase the density of deuterium in titanium beyond its initial value using a deuterium plasma enrichment plan. The target for enrichment is a copper disc coated with titanium, which is immersed in deuterium plasma to implant deuterium ions. The target is connected to a high-power modulator and subjected to negative voltage pulses. These pulses accelerate deuterium ions towards the target, causing them to penetrate and implant into it. Initially, due to the low diffusion coefficient of titanium, the incident ions do not diffuse quickly and accumulate near the target surface. The diffusion equation describes the predicted distribution of ions inside the target, revealing that the deuterium concentration in titanium can be significantly increased within a few weeks, exceeding the initial value by several orders of magnitude.

Abstract Liquid wastes containing fission fragments are valuable sources of useful radioisotopes that can be extracted using suitable radiochemical methods. This article addresses the challenge of unavailable waste by simulating a solution equivalent to the liquid waste from a 99Mo production facility using the MCNPX code and preparing it with laboratory-available salts. Various radiotracers of elements were subsequently produced via the neutron activation method and added to the equivalent solution. Investigations focused on tracing cerium in the process, utilizing the 145.4 keV gamma radiation from ¹⁴¹Ce produced during activation. The irradiation mechanism and spectroscopy were simulated using the MCNPX code, and the results were compared with experimental measurements.

Abstract The reliability of the transmission grid significantly influences the occurrence frequency of Loss of Offsite Power (LOOP), the predominant core damage-inducing event in non-passive nuclear power plants (NPPs). With the increasing integration of wind farms into transmission grids for economic and environmental reasons, grid stability is affected. Therefore, it is imperative to investigate how these changes impact the frequency of Grid-Related LOOP (GR-LOOP). This study examines the effects of varying grid conditions, specifically wind farm penetration levels, on GR-LOOP occurrence frequency. A proposed methodology is applied to grids under different operational scenarios, considering varying percentages of wind farm penetration, different loading conditions, and power flow methods. The frequency of GR-LOOP scenarios is evaluated for grids with 0%, 10%, and 20% wind penetration before a 3-phase short circuit fault occurs on transmission lines. Results show that at the riskiest power plant location, the occurrence frequencies are 3.23E-05, 4.49E-05, and 4.86E-05 per reactor-year for the respective wind penetration levels. Conversely, at the safest location, frequencies are 8.58E-06, 1.55E-05, and 1.52E-05 per reactor-year. These findings underscore the significant impact of wind farm penetration on GR-LOOP frequency in mixed grids. The non-linear and non-proportional changes in frequency with increasing wind penetration highlight the necessity of integrating such considerations into safety assessments for nuclear power plants.

Abstract This study investigates the effect of coherent state superposition on quantum scissors. The scissor is subjected to ideal single-photon, vacuum state, and superpositions of coherent states as incident fields. Detectors are employed to measure single photons and zero photons, resulting in a superposition state of single-photon and vacuum states at the output. The study calculates the scissor's probability of success, amplification factor, fidelity, and efficiency factor. The probability of success depends on the coherent field's amplitude, incident field phase, and transmission coefficients of the beam splitters. The maximum probability of success reaches 25%, attributed to even coherent state superpositions. Quantum scissors demonstrate the capability to amplify states under specific conditions. Results indicate maximum amplification when the incident field phase approximates π. Besides amplification, this phase significantly influences the distribution of zero and single-photon states in the superposition output. Thus, altering the incident field phase or beam splitter transmission can modify this distribution. For a fixed incident field intensity, closer proximity of the incident phase to π correlates with reduced scissor efficiency. These findings underscore how quantum scissors can characterize coherent state superpositions due to their sensitivity to incident state characteristics.

Abstract The experimental investigation of supercontinuum generation in deionized water using an amplified Ti:sapphire femtosecond laser pulses is presented. During the propagation of femtosecond pulses in deionized water, self-focusing leads to filamentation and subsequent supercontinuum generation. The effects of varying the focal point distance from the cell and altering the incident femtosecond laser pulse energy on the supercontinuum spectra were studied. Near critical power, ring and cone emissions contribute significantly to the continuum. The central white light part covers the output signal at very high laser powers. A supercontinuum emission with a bandwidth of 600 nm was achieved using a laser pulse energy of 1.19 mJ. The spectrum broadening, due to Kerr self-focusing and plasma defocusing, was analyzed for 37 femtosecond laser pulses with average powers ranging from 420 to 3800 times the critical power. Increasing the input pulse energy to 460 µJ, corresponding to 2900 times the critical power, resulted in an asymmetric broadening of the spectrum, with the blue edge shifting to 400 nm. Further increases in energy showed no additional shift due to intensity clamping.

Abstract Low-intensity laser prepulse (<10^13 W cm^−2, nanosecond duration and <10^17 W cm^−2, picosecond duration) significantly impact experiments on laser-induced proton generation, often constraining the performance of proton sources from high-intensity lasers. Depending on the intensity regime and target thickness, various effects can result from the prepulse. This study focuses on hydrodynamic simulations using a fluid code to replicate real-world conditions, specifically targeting the prepulse parameters of the ATLAS laser facility (including a 20-picosecond duration) across different target thicknesses (1-0.12 μm). The simulations extract target parameters at the end of the prepulse phase. For these specific prepulse conditions, the results indicate that a target thickness of 0.25 μm optimizes the interaction with the main laser pulse. Thinner targets exhibit altered density profiles on the rear surface, thereby reducing acceleration efficiency.

Abstract This paper investigates the interaction mechanism of a single collective laser pulse and two counter-propagating laser pulses (with the total field amplitude divided between them in varying ratios) with a near-critical density plasma using 1D3V Particle-in-Cell (PIC) simulations. The study focuses on the dependence of key properties of the emitted photon bunch on the amplitude ratio, comparing them with the single collective pulse scenario. For counter-propagating pulses, nonlinear inverse Compton scattering results in the maximum photon emission occurring early during the collision of the pulses. The directionality of emitted photons along the pulse propagation direction is highest for counter-propagating pulses and lowest for the single collective pulse. Larger differences in divided field amplitudes bring the results closer to those of a single collective pulse. The maximum electron energy cutoff and emitter number are observed for counter-propagating pulses with amplitude ratios of 0.9:0.1 and 0.8:0.2, respectively, while the ratio 0.5:0.5 shows minimal values. The peak photon density corresponds to the highest cutoff energy, observed for the 0.9:0.1 counter-propagating pulses. Furthermore, the total absorbed energy by electrons and photons directly correlates with the injected electromagnetic energy into the system, being highest for the single pulse scenario. However, the overall electromagnetic radiation emission is maximized for counter-propagating pulses. These findings provide insights valuable for optimizing high-power laser interactions with plasmas and their applications.

Abstract In this research, the gamma ray protective properties of iron-doped nano-hydroxides were evaluated by calculating effective quantities such as the half-value layer (HVL), mean free path (MFP), mass attenuation coefficient (𝜇m) and linear attenuation coefficient (LAC) in the range of 0.015 to 15 MeV using the Geant4 Monte Carlo simulation tool. To investigate the quantitative difference between the mass attenuation coefficient of nano-materials and normal materials, the simulation results were compared with data extracted from the NIST-XCOM database, which can only calculate the mass attenuation coefficient of normal materials. In this comparison, it was observed that the data extracted from the database and the results of the Geant4 simulation tool differed as the concentration of iron contamination increased. The percentage of deviation (RD) between the data extracted from the database and the results of the Geant4 simulation tool increased from 0.1 to 3.2%. This deviation was attributed the increase in the concentration of nano-iron contamination in the composition. Therefore, the nano-hydroxide composition with the highest percentage of iron contamination (Fe-HAp-48) had the most favorable protective composition in terms of density compared to other selected protective materials. This composition, which is lightweight and antibacterial, provides effective protection against gamma rays in the specified energy range.

Abstract One of the primary challenges faced by operational personnel at the Tehran Research Reactor (TRR) is the handling and management of spent fuel assemblies. Estimating the radiation dose from these fuels in the air is crucial for assessing risks and implementing necessary safety measures during transportation. Due to the high radiation intensity and dose rates of spent fuels, direct measurement of their airborne dose rate is impractical. Instead, the dose rate is measured within the reactor pool water and then converted to an estimate for the air using conversion factors. This research focuses on estimating the dose conversion factor from water to air for gamma rays emitted by spent fuels at TRR. Experimental data from a fission molybdenum source and Monte Carlo simulations using the MCNP code were utilized to determine this conversion factor. The results obtained from both methods demonstrate relatively good agreement with each other.

Abstract From an economic perspective, increasing nuclear fuel burnup (up to 50 GWd/t) and thereby extending reactor cycles are compelling reasons to develop models that incorporate High Burnup Structure (HBS) phenomena into fuel performance codes. This research focuses on investigating the behavior of fission gases within HBS by implementing two semi-empirical models in the MSFGR-02 code. These models describe the formation of HBS, encompassing polygonization (recrystallization) and the release of intra-granular fission gas. The study utilizes grain size measurements obtained from references and applies them to radial positions where data reconstruction was incomplete. This approach yields semi-empirical relationships for grain radius size and restructured volumetric fraction as functions of fuel burnup. Comparisons between changes in fission gas concentration during irradiation until HBS formation and experimental data from references demonstrate acceptable agreement.

Abstract Copper-67 (⁶⁷Cu) is a suitable radioisotope for targeted radionuclide therapy, nuclear medicine imaging, and dosimetry calculations during treatment. This study investigates the optimal reaction for producing ⁶⁷Cu in cyclotron accelerators. The excitation functions of the reactions ⁶⁸Zn(p,2p)⁶⁷Cu, ⁷⁰Zn(p,α)⁶⁷Cu, ⁷⁰Zn(d,x)⁶⁷Cu, and ⁶⁴Ni(α,p)⁶⁷Cu were simulated in the energy range of 0 to 100 MeV using TALYS-1.96 and EMPIRE-3.2.2 Monte Carlo codes. The target thickness and mass stopping power of these reactions were calculated using the SRIM-2013 code. The theoretical yield of these reactions was derived from the excitation function data and mass stopping power, and compared with experimental results. The maximum yield of ⁶⁷Cu production without ⁶⁴Cu contamination at energies of 100, 35, 40, and 30 MeV for the reactions ⁶⁸Zn(p,2p)⁶⁷Cu, ⁷⁰Zn(p,α)⁶⁷Cu, ⁷⁰Zn(d,x)⁶⁷Cu, and ⁶⁴Ni(α,p)⁶⁷Cu, respectively, were obtained. According to the results from EMPIRE and TALYS codes, these yields were 0.442, 1.248, 9.842, 7.77, 21.131, 11.542, 1.638, and 1.621 MBq/µAh, respectively. Based on the obtained results and their comparison with experimental data, the ⁷⁰Zn(d,x)⁶⁷Cu reaction at 40 MeV is identified as the best reaction for producing ⁶⁷Cu without ⁶⁴Cu contamination.

Abstract In this research using the MCNPX code, calculations were done for nuclear designing of portable two-chamber gamma irradiator facility for irradiation of grains and legumes according to international standards. Calculations were made in two parts of dose uniformity ratio and mass flow rate of the irradiated product, as well as gamma-ray shielding using 100 kCi Cobalt-60 line sources, model GIK-A6m of Mayak Co., Russia. The dose uniformity ratios of internal and external irradiation chambers were found to be about 1.77 and 2.18, respectively. Also, the mass flow rate of an irradiated typical grain with a bulk density of 800 kg m-3 was calculated to be about 3.2 ton h-1. A typical grain will receive a dose between 300-656 Gy, which is less than the maximum recommended limit of absorbed dose for grains and legumes (1 kGy) in purpose of shelf-life extension and insect disinfestation by the IAEA. According to ANSI/HPS N43.7, the leakage dose rate at a distance of 5 cm far from the surface of the irradiator in the irradiate mode and for restricted areas, was calculated to be less than 200 µSv/h (maximum permissible radiation level). The results showed that the lead shield of irradiator facility with maximum thickness of 29 cm, easily blocks the emitted gamma rays and working with such a facility would not pose any radiation risk to the employees. Finally, the energy efficiency of the facility was estimated to be about 25% with an increase of about 10.5% due to the addition of external chamber.