Ramin Mehrabifard
Abstract
Dielectric barrier discharge (DBD) plasma is used for various applications. DBD is also one of the most efficient and low-cost methods for active fluid flow control. In this study, a detailed physical model of DBD in atmospheric pressure at 1 kV DC voltage is developed with COMSOL Multiphysics software. ...
Read More
Dielectric barrier discharge (DBD) plasma is used for various applications. DBD is also one of the most efficient and low-cost methods for active fluid flow control. In this study, a detailed physical model of DBD in atmospheric pressure at 1 kV DC voltage is developed with COMSOL Multiphysics software. Argon gas is also used as a background gas and electrodes are assumed to be copper. Plasma parameters such as electron and ion density, electric field, potential, and temperature for different gap distances of electrodes (1.0 mm, 0.9 mm, 0.8 mm) and different dielectric types (Quartz, Silica Glass, Mica). The results of the simulation show that the longitudinal distance of the grounded electrodes to the power electrodes has a direct influence on parameters such as electron temperature, and electron and ion density which are the main factors of fluid flow control. These parameters have the maximum value when Mica is used as a dielectric and the lowest value when Silica Glass is utilized.
Ehsan Boustani; Mostafa Hassanzadeh; Rohollah Ahangari
Abstract
The occurrence of core uncovering following a loss of coolant accident is conceivable and should be taken into account for its significant possible consequences. Source terms are calculated using ORIGEN 2.1 code, and the gamma dose of the uncovered core is calculated for three different normal and anticipated ...
Read More
The occurrence of core uncovering following a loss of coolant accident is conceivable and should be taken into account for its significant possible consequences. Source terms are calculated using ORIGEN 2.1 code, and the gamma dose of the uncovered core is calculated for three different normal and anticipated accidents scenarios. Under containment gamma dose rates have been calculated analytically as well as using MCNPX 2.6.0 code. The uncovered core of the Tehran research reactor is supposed to operate in nominated power of 5 MW for 30 days. The results illustrated that the under-containment dose rate of gamma in some locations would be about 200 Svh-1, far from the annual occupational exposure limit of 50 mSv. For preventing this occurrence, it would be possible to use an emergency make-up tank as an engineered safety feature, with functions of the avoidance of damaging fuel after the loss of coolant accident as well as controlling exposure from the core.
Reza Pourimani; Saeed Ghahani; Parisa Nobakht; Iman Mirzae Moghadam
Abstract
Today, with the development of nuclear technology and radiation therapy equipment, radiation protection is important. This study aimed to design heavy concrete with high compressive strength and effective protection against neutron and gamma rays. In this study, 11 types of concrete with different mixing ...
Read More
Today, with the development of nuclear technology and radiation therapy equipment, radiation protection is important. This study aimed to design heavy concrete with high compressive strength and effective protection against neutron and gamma rays. In this study, 11 types of concrete with different mixing designs including 88 samples were made. In these samples, iron ore aggregates galena, limonite, hematite, polypropylene fibers, nanoparticles, micro-particles of silicon, and B4C powder have been used. Concrete quality coefficient, compressive strength, gamma, and neutron attenuation coefficients were measured for all samples. Also, the neutron attenuation coefficient for all samples was calculated using the Monte Carlo simulation (MCNPX) code and compared with the experimental values. The density, neutron attenuation coefficient, and compressive strength of concrete samples varied from 2.37 to 3.17 g.cm-3, from 0.0162 to 0.0306 cm2.g-1, and from 48.0 to 81.3 MPa respectively. The linear gamma attenuation coefficient and gamma-ray tenth value layer (TVL) were obtained from 0.148 to 0.398 cm-1 and 15.74 to 5.85 cm respectively. These results showed that the highest neutron and gamma attenuation coefficients were obtained for concrete containing 70% galena iron ore and 20% boron carbide and the highest compressive strength belonged to sample G15 containing 15% galena iron ore and 1.8% boron carbide. G70 was the best concrete regarding the quality factor, defined as the product of multiplying the compressive strength and linear attenuation coefficients of neutron and gamma.
Elham Edalatkhah; Shahab Sheibani
Abstract
By expanding the applications of GEM detectors, a newer pattern of such detectors was introduced in 2004, named THGEM detectors. In this work, a sample of an X-ray detector was designed and constructed using 2cm×2cm THGEMs domestically produced with a thickness of 250 μm, a hole diameter of ...
Read More
By expanding the applications of GEM detectors, a newer pattern of such detectors was introduced in 2004, named THGEM detectors. In this work, a sample of an X-ray detector was designed and constructed using 2cm×2cm THGEMs domestically produced with a thickness of 250 μm, a hole diameter of 300 μm and a pitch of 500 μm, for the first time. The triple THGEM detector working in Ar/CO2 gas mixture was characterized. Influence of gas pressure and gas mixture on gain of the detector was investigated. Results show the detector operated in a stable mode with no discharges. The gain of the detector increased with high voltage across the THGEM electrodes exponentially. This verified the performance of a detector as a proportional counter. Also, the detector’s gain is maximum at Ar/CO2 (80/20) gas mixture and voltage of 700 V applied to each multiplier. The detector is promising for localization applications such as particle physics experiments.
Hamed Khodadadi; Kamyar Sabetghadam
Abstract
Probabilistic uncertainty and sensitivity analysis is frequently recommended for safety and reliability assessment of computer simulations. For this purpose, SUAP has been developed, and its latest version is capable of working on analysis results obtained using five well-known nuclear codes (i.e. FRAPCON, ...
Read More
Probabilistic uncertainty and sensitivity analysis is frequently recommended for safety and reliability assessment of computer simulations. For this purpose, SUAP has been developed, and its latest version is capable of working on analysis results obtained using five well-known nuclear codes (i.e. FRAPCON, FRAPTRAN, FEMAXI, MCNP, and COBRA). SUAP provides support to properly quantify input uncertainties as to probability distributions and appropriate dependency functions. Using the Monte-Carlo sampling method, random combinations of different uncertain input parameters are generated and used to make input files for the corresponding code applied for the modeling. To quantify uncertainties, SUAP determines the variation range for each specific output parameter at any chosen time and/or location. Moreover, sensitivity analysis is accomplished based on the Spearman correlation. In this study, in order to evaluate SUAP applicability, UQ&SA for fuel performance modeling of VVER-1000 fuel rods using FRAPCON code has been accomplished. Acquired results exhibit the possible range of uncertainties in fuel centerline temperature, as well as the importance of different uncertain input parameters on that.
Roohalah Mirzaeian; Seyede Nasrin HoseiniMotlagh; Mahboobeh Shaghaghian
Abstract
In recent years, various designs for controlled thermonuclear fusion based on the p11B reaction have been reviewed and optimized. In this article, to innovate in achieving a better power and energy gain of neutron-free p11B fusion reaction, the improvement of the cross-section and also the kinetic effects. ...
Read More
In recent years, various designs for controlled thermonuclear fusion based on the p11B reaction have been reviewed and optimized. In this article, to innovate in achieving a better power and energy gain of neutron-free p11B fusion reaction, the improvement of the cross-section and also the kinetic effects. Then, the effects of bremsstrahlung radiation and ion and electron energy exchange rate have been evaluated by introducing relativistic effects and its role on improving fusion energy gain. As a result, the temperature of the electron is kept lower than that of the ion, which improves fuel performance. Finally, it leads to an increase in the number of protons at higher energies compared to the pure Maxwellian distribution and it causes a significant increase in reactivity compared to previous research. Also, the number of alpha particles obtained through calculations coincides with the latest research and leads to an enhancement of approximately 13%. This means that by improving the fusion cross-section of p11B, our calculations show that considering the avalanche effects, the range of achievable energy gain in the temperature range of 300 to 500 keV and the stable characteristic time of 0.64 ps reaches 89 to 111. While in the same temperature range and with the stable characteristic time of 0.74 ps, regardless of the improved cross-section, the energy gain range is 75 to 98.
Saba Khatami; Mohammad Mahdavi; Sohail Khoshbinfar
Abstract
In this research, the effect of deuterium beam energy distribution function resulting from TNSA and RPA mechanisms on the fast ignition of D/He-3 fuel pellet has been investigated. The fuel is irradiated with a deuterium beam through a conical guide. The energy distribution function will be different ...
Read More
In this research, the effect of deuterium beam energy distribution function resulting from TNSA and RPA mechanisms on the fast ignition of D/He-3 fuel pellet has been investigated. The fuel is irradiated with a deuterium beam through a conical guide. The energy distribution function will be different in different mechanisms. Penetration depth and stopping power of ignitor beam with mono- energy, Maxwellian and Gaussian distribution of energy are calculated. Calculations show that the Maxwellian beam from TNSA mechanism, penetrates up to about 100 μm in the fuel and the height of deposition peak is still in plasma corona. The height of the peak has also increased about 25 times compared to the case where the Gaussian beam is considered. Also, the obtained results are shown that the energy deposit of the deuterium beam resulting the RPA mechanism will be completely localized and will be more concentrated in the dense fuel core.
Farshid Pourranjbar; Elham Edalatkhah; Seyed Mohammad Mahdi Abtahi
Abstract
Fricke gel dosimeters obtained by modifications on standard Fricke dosimeter presents some advantages like easy preparation, tissue equivalence, good reproducibility and dose mapping. In this work, dose response characteristics of Gelatin Fricke gel dosimeters ...
Read More
Fricke gel dosimeters obtained by modifications on standard Fricke dosimeter presents some advantages like easy preparation, tissue equivalence, good reproducibility and dose mapping. In this work, dose response characteristics of Gelatin Fricke gel dosimeters was investigated and compared with Fricke agarose gel dosimeters in terms of sesitivity. After prepration of three different formulation of Gelatin Fricke gel dosimeters and gamma irradiation of the samples, a spectrophotometer was applied to measure the optical absorbance of the samples. Results indicate a linear dose range response of 10 to 30 Gy, as well as increased gelatin concentrations cause the sensitivity of the dosimeter to detereorate with a 80% reduction of dose response for a change in gelatin concentration from 3 to 8 weight percent. Obtained coefficient variation verifies the good repeatability of the gel response. The gel dosimeter has no dose rate dependence. Comparison of the most sensitive Gelatin Fricke gel sample with the prepared Fricke agarose gel samples confirm that Fricke agarose dosimeter is more sensitive than Gelatin Fricke gel dosimeter.
Reza Pourimani; Monire Mohebian; Mobina Abdi
Abstract
Nuclear radiations are harmful to the human body. The main sources of nuclear radiation are the decay chains of U-238, U-235, and Th-232 and also some radionuclides as K-40, which are present in small amounts in the materials of the earth's crust, including plants, rocks, soil and water. Radioactive ...
Read More
Nuclear radiations are harmful to the human body. The main sources of nuclear radiation are the decay chains of U-238, U-235, and Th-232 and also some radionuclides as K-40, which are present in small amounts in the materials of the earth's crust, including plants, rocks, soil and water. Radioactive substances are transferred to the human body in a variety of ways, including plant and animal products. Therefore, it is very important to determine the amount of radioactive substances in food products. In this research, seven samples of pistachios with different types were collected from Tehran markets in Iran. In this project, ultra-pure germanium spectroscopy system model GCD30195 was used. The specific activities of Ra-226, Th-232 and K-40 varied from <1.96 to 9.86, from 1.21 to 1.95, and from 317.22 to 382.80 Bq.kg-1. The artificial radionuclide of Cs-137 in all samples was lower than minimum detectable value (MDA). Calculations of the radiological impact showed that consumption of pistachios would endanger human health. The results of this study also showed that the amount of natural radionuclides in pistachio cores is higher than pistachio shells.
Morteza Akbari; Farrokh Khoshahval
Abstract
In this research, the governing dynamic equations of the Bushehr NPP core are studied and modeled using Matlab (Simulink) software. The point kinetic equation with the temperature feedbacks and the fuel-coolant energy balance equations in the time domain were used for this purpose. The model is validated ...
Read More
In this research, the governing dynamic equations of the Bushehr NPP core are studied and modeled using Matlab (Simulink) software. The point kinetic equation with the temperature feedbacks and the fuel-coolant energy balance equations in the time domain were used for this purpose. The model is validated against the rod drop accident data available in BNPP-1 FSAR, and they agreed. Then, this time-domain model is used to find the maximum movement speed of the control rods. For this goal, linear and non-linear rod movement equations have been modeled. In this regard, the maximum withdrawal speed of the working bank (H10) with a worth of 1.1 dollars has been investigated. Using the linear CR model, a speed limit of 9 cm.s-1 has been obtained to prevent the initiation of a reactor trip. The maximum speed using the non-linear model of the CR was found out to be dependent on its initial position. Thus, in three positions of the H10 bank: 100%, 80%, and 50% of the length inside the reactor, the maximum withdrawal speed values were valuated 11.5, 7.7, and 4.4 cm.s-1 respectively. According to the results, among the reactor parameters including power, period, and fuel temperature, which are monitored by the reactor protection system to initiate the reactor trip, the reactor power is the limiting factor for specifying the maximum withdrawal speed. This study is performed using time domain analysis, and the obtained results are consistent with the results reported in the previous research using Laplace transform approach.
Leyli Mogheiseh; Ali Asghar Mowlavi; Sayyed Bijan Jia; Reza Shamsabadi
Abstract
Proton therapy of liver tumors can be challenging due to the absorbed dose of produced secondary particles in non-target organs. This study aims to evaluate the absorbed dose of secondary particles during the proton therapy of liver cancer through the MCNPX Monte Carlo (MC) code by a simplified MIRD-UF ...
Read More
Proton therapy of liver tumors can be challenging due to the absorbed dose of produced secondary particles in non-target organs. This study aims to evaluate the absorbed dose of secondary particles during the proton therapy of liver cancer through the MCNPX Monte Carlo (MC) code by a simplified MIRD-UF standard phantom. At first, a simplified MC model of MIRD-UF standard phantom was simulated using MCNPX. After the proper proton energies calculation ranging from 90 to 120 MeV for 4×4×4 cm3 tumor irradiation, mesh tally type 3 and F6 tally were used to calculate the depth dose profiles as well as the absorbed dose of protons and secondary particles in non-involved organs. The obtained results illustrated that the fluence of internal secondary particles doses was considerably small in comparison with primary protons. Furthermore, most of neutrons and photons doses were absorbed around the liver tissue for all performed proton energies (i.e., 90 and 120 MeV) which non-target organs did not receive a significant high dose. Furthermore, the absorbed dose of secondary photons and neutrons had slight variations in considered normal tissues near the liver. The calculated results in this study indicated that during the proton therapy of liver cancer, the most contribution of the secondary particle doses was absorbed inside the liver tissue. Hence, it can be expected the probable side effects (secondary cancers) associated with the liver cancer proton therapy may be decreased however, the presence of secondary particles should not be ignored.
Elham Edalatkhah; Mahsa Sedighi; Payvand Taherparvar
Abstract
Gamma radiation indicators are appropriate tools for monitoring visually whether or not the irradiation process has been carried out properly. Among chemical radiation indicators available worldwide, a few are suitable for monitoring low dose ranges (especially for blood irradiation, below 50 Gy). Addressing ...
Read More
Gamma radiation indicators are appropriate tools for monitoring visually whether or not the irradiation process has been carried out properly. Among chemical radiation indicators available worldwide, a few are suitable for monitoring low dose ranges (especially for blood irradiation, below 50 Gy). Addressing this scope, PVA-Fricke gel was proposed in this work. Irradiation of the prepared PVA-Fricke gel samples was performed by Co-60 gamma cell unit up to a dose of 80 Gy. Color change of the samples was observed from orange to purple proportional to increasing absorbed dose. Prepared samples were divided into three groups, kept at different environmental conditions, to investigate stability of the gel against temperature and light. Results revealed that the irradiated samples kept at dark and refrigerator were stable for seven days. Optical absorbance measurement of the samples also estimated pre- and post-irradiation color stability. The gel can be easily used to identify processed and unprocessed products in blood irradiation. Although the gel is designed to be a qualitative indicator, it is also a good quantitative dosimeter for gamma rays.
Measurement of Radiation and Radioactivity
Hora Kavarian; Armin Mosayebi; Hamideh Daneshvar
Abstract
In this research work, commercial beta-tricalcium phosphate powder is converted into tablets by pressure-less sintering method. Thermoluminescence responses of tablet and powder samples in the dose range of 20 to 1500 Gy have been compared and effective factors in tablet conversion such as mass in the ...
Read More
In this research work, commercial beta-tricalcium phosphate powder is converted into tablets by pressure-less sintering method. Thermoluminescence responses of tablet and powder samples in the dose range of 20 to 1500 Gy have been compared and effective factors in tablet conversion such as mass in the range of 30 to 60 mg, force between 1 to 3 N, concentration of granulating solution and tablet diameter in the range of 0.4 to 15 mm are investigated based on the results of dosimetric response and tablet hardness. The results show that by turning into tablets, the grain size increases, and the possibility of the first-order kinetics increases by the conversion of powders into tablets. It is possible to achieve a better dosimetric response than the it’s powder by applying suitable conditions for turning into tablets; also, the diameter of the sample can affect hardness, and it is better to make the tablets with a smaller size. Based on the results obtained from fading, reproducibility, sensitivity, peak shaping of the glow curve, and microhardness measurement, it can be seen that the samples that have been subjected to less pressure perform better and in order to achieve the desired results of converting to TLD dosimetry tablets, it is better to use more mass for tablets if more pressure is needed.
Nuclear Reactor science and Technology
Ali Zahian; Mahdi Aghaie
Abstract
In this analysis, nanofluid properties are evaluated by interaction correlations between particles using molecular dynamics (MD) method, and thermal-hydraulics characteristics of nanofluids in a WWER-1000 reactor is investigated by Computational Fluid Dynamics (CFD). This study conceptualizes power increase ...
Read More
In this analysis, nanofluid properties are evaluated by interaction correlations between particles using molecular dynamics (MD) method, and thermal-hydraulics characteristics of nanofluids in a WWER-1000 reactor is investigated by Computational Fluid Dynamics (CFD). This study conceptualizes power increase by changing the cooling from pure water to nanofluid without changing the safety parameters. The Copper nanoparticles are used in primary loop cooling system, to evaluate the heat removal from the core. Thermophysical properties such as thermal conductivity and shear viscosity of Cu-Water nanofluids are obtained by MD in operating pressure and temperature of the Bushehr reactor core. These properties have been used in thermal-hydraulics analysis and nanofluids are considered as a homogeneous fluid. Thermal hydraulic properties of coolant have been calculated for different volume fractions of nanofluids. Thermal hydraulic simulation illustrated enhancement of the thermal characteristics of the core, due to the increment in heat transfer coefficient and thermal diffusivity. The thermal-hydraulic analysis of the reactor core has been performed in steady state at different powers. The requirements for changing the reactor power are not to change the fuel center temperature and Outer Cladding Surface temperature compared to the current state.
Nuclear Reactor science and Technology
Mohammad Askari; Nikoo Darestani Farahani; Mehdi Bakhshzad Mahmoudi; Fereydoun Abbasi Davani
Abstract
Metal surface cleaning or etching techniques using reactive plasma are emerging as one of the dry processing techniques for surface contaminants with high bond energy, especially for cleaning and decontamination of nuclear components and equipment. In this study, the plasma reaction due to the discharge ...
Read More
Metal surface cleaning or etching techniques using reactive plasma are emerging as one of the dry processing techniques for surface contaminants with high bond energy, especially for cleaning and decontamination of nuclear components and equipment. In this study, the plasma reaction due to the discharge of a dielectric barrier of a mixture of 95% helium and 5% fluorine with cobalt oxide film (Co3O4) grown on the surface of stainless steel 304 was studied experimentally. Experimental results show that cobalt oxide becomes a powder after plasma irradiation and is easily separated from the surface of the base metal. The optimal plasma generating conditions of the dielectric barrier discharge used in this experimental study were obtained at atmospheric pressure, voltage 4.5 kV, and frequency 25 kHz with an etching rate of 10.875 μmol.min-1. The samples were analyzed before and after plasma irradiation, using Scanning Electron Microscopy with Energy Dispersive X-ray spectroscopy and the purification rate was performed using a sequential weighting of the samples with scales 10-4 g accurately obtained. The results show the ability of this method to effectively remove the surface contamination of cobalt from the surface of stainless steel 304.
Monte Carlo Method
Ali Azizi Ganjgah; Payvand Taherparvar
Abstract
Radiation therapy aims to maximize doses to cancer cells while minimizing damage to normal tissues. Today, nanoparticles containing high-atomic-number elements, such as gold, gadolinium, and silver, have proven effective as radiosensitizers in radiotherapy to enhance dose delivery for cancer treatment. ...
Read More
Radiation therapy aims to maximize doses to cancer cells while minimizing damage to normal tissues. Today, nanoparticles containing high-atomic-number elements, such as gold, gadolinium, and silver, have proven effective as radiosensitizers in radiotherapy to enhance dose delivery for cancer treatment. In this study, we used the Geant4-DNA toolkit to investigate the effects of multiple nanoparticles (NPs) with varying sizes (radius= 3.15 to 5 nm) on DNA damage when exposed to monoenergetic photons with energies of 15, 40, 50, and 68 keV. Direct and indirect single-strand breaks (SSBs), double-strand breaks (DSBs), and hybrid double-strand breaks (Hybrid DSBs) were calculated in the presence and absence of 1 to 4 nanoparticles (NPs) of the same total volume of gold, gadolinium, and silver nanoparticles for the 1ZBB model (selected from the Protein Data Bank (PDB) library). The results show that increasing the number of gold, gadolinium, and silver NPs and decreasing the photon beam energy increases the total number of strand breaks. Furthermore, gold nanoparticles (GNPs) are more effective options than gadolinium nanoparticles (GdNPs), and silver nanoparticles (SNPs) for inhibiting and controlling cancer cells.
Measurement of Radiation and Radioactivity
Zohreh Gholamzadeh; Reza Ebrahimzadeh; Mohammad Hossein Choopan Dastjerdi; Javad Mokhtari
Abstract
New nitrile butadiene rubber (NBR) materials are being considered to use for neutron shielding especially for the positions which needs a flexible neutron shield. Such light, low-cost, and suitable material could be used for sealing of the gaps or even for shielding of low radiation environments. In ...
Read More
New nitrile butadiene rubber (NBR) materials are being considered to use for neutron shielding especially for the positions which needs a flexible neutron shield. Such light, low-cost, and suitable material could be used for sealing of the gaps or even for shielding of low radiation environments. In the present work, experimental investigation of NBR shielding performance of neutrons and gamma rays was proposed using the beam line of the Isfahan Miniature Neutron Source Reactor . MCNPX code was used to simulate the 30 kW research reactor beam line. Six NBR sheet with 2 cm thickness were used at the outlet of the beam line respectively to measure its neutron shielding as well as gamma shielding power on thickness. The experiment situations were modeled using the computational code. The obtained results showed the flexible and cheap material could be used as a good neutron shield while it acts as a very weak shield for gamma rays too. Also there is good conformity between simulation and experimental data with maximum 37% relative discrepancy.
Particle Accelerators, Ion sources
Sajad Hajikhani; Ramin Mehrabifard; Hamed Soltani Ahmadi
Abstract
Plasma technology has undeniably revolutionized industrial processes in recent decades. Atmospheric pressure plasma (APP) has emerged as a prominent and widely applicable tool in various scientific disciplines. Notably, plasma-assisted flow control has become a subject of intense interest, particularly ...
Read More
Plasma technology has undeniably revolutionized industrial processes in recent decades. Atmospheric pressure plasma (APP) has emerged as a prominent and widely applicable tool in various scientific disciplines. Notably, plasma-assisted flow control has become a subject of intense interest, particularly applying surface dielectric barrier discharge (SDBD) plasma actuators for aerodynamic flow control. In this study, a two-dimensional model of the SDBD plasma actuator is developed using the COMSOL Multiphysics program, incorporating air gas discharge reactions with N2/O2/Ar gases in specific ratios (0.78, 0.21, 0.01). The investigation focuses on the impact of dielectric materials (mica, silica glass, quartz, and polytetrafluoroethylene (PTFE)) on plasma characteristics and body force within the plasma actuator under constant input parameters. Moreover, the study explores how variable pressure (760, 660, and 560 torr) in different applications influences plasma properties, ultimately affecting the magnitude of the body force in the plasma actuator. These findings contribute to optimizing plasma technology for flow control applications and enhance industrial efficiency and performance.
Radiation Applications
Hamed Kargaran
Abstract
The estimation of flux in radiation transport Monte Carlo problems needs to calculate the volumes and surface areas of the geometric regions. The particle flux is often estimated as the track length per unit volume or the number of particles crossing a surface per unit area in Monte Carlo transport problems. ...
Read More
The estimation of flux in radiation transport Monte Carlo problems needs to calculate the volumes and surface areas of the geometric regions. The particle flux is often estimated as the track length per unit volume or the number of particles crossing a surface per unit area in Monte Carlo transport problems. Various representations such as constructive solid geometry (CSG), boundary representation (B-Rep), and combinatorial geometry (CG) are proposed in the literature for geometry modeling and calculation of surface area and volume. MCNP series and OpenMC as Monte Carlo particle transport codes utilize CG modeling and are not able to calculate surface area as well as volume for non-rotationally symmetric or non-polyhedral cells. In this work, a comprehensive approach based on the Cauchy-Crofton formula using the Monte Carlo method has been implemented to the radiation transport codes as an extra module for computing surface area and volume of complex geometries. We used a random sampling procedure to create the required probe lines and points in the computational approach. The results show that this method can accurately compute surface areas and volumes of complex geometries with a relative error of less than 0.1% and a short computation time of a few seconds, which is not achievable with the cuurent MCNP and OpenMC modules.
Measurement of Radiation and Radioactivity
Nahid Hajiloo; Mostafa Mohammadi; Omid N. Ghodsi; Hamideh Daneshvar; Soheil Moghtader
Abstract
The International Atomic Energy Agency (IAEA), sends dosimeters annually to Secondary Standard Dosimetry Laboratories (SSDL) around the world, to calibrate their radiation field. Therefore, they mainly send thermo-luminescent dosimeters as transfer dosimeters to the SSDL laboratories, to be irradiated ...
Read More
The International Atomic Energy Agency (IAEA), sends dosimeters annually to Secondary Standard Dosimetry Laboratories (SSDL) around the world, to calibrate their radiation field. Therefore, they mainly send thermo-luminescent dosimeters as transfer dosimeters to the SSDL laboratories, to be irradiated under the requested conditions and sent back to the IAEA laboratories for reading. In this way, by reading the dosimeters, the uncertainty of the dosimetry carried out by SSDL and, consequently, the calibration of its radiation fields is determined. In this research, with the aim of feasibility of comparative dosimetry program by SSDL laboratory for radiation therapy centers, this program was carried out for a number of centers. In this way, TLD-700 thermoluminescence dosimeters were irradiated in the same conditions in the SSDL laboratory and also in the selected centers to a certain amount. After reading and applying the correction coefficients and calibration factors, the obtained results were compared with the measurement results using ion chamber reference dosimeter. In this work the uncertainty of the dosimetry using TLD tablet was less than 1.12% in comparison to the reference ionization chamber dosimeter and was within the acceptable range of less than 3%.
Experimental and Theoretical Nuclear Physics
Zeinab Sadat Imani; Omidreza Kakuee; Yavar Taghipour Azar; Amir Abbas Sabouri Dodaran
Abstract
The production of light, energetic and low-flux ions as a secondary beam caused by nuclear reaction can be used in various branches of nuclear physics. Due to the limited availability of energy in small laboratories equipped with electrostatic accelerators, accessing energetic light particles is crucial. ...
Read More
The production of light, energetic and low-flux ions as a secondary beam caused by nuclear reaction can be used in various branches of nuclear physics. Due to the limited availability of energy in small laboratories equipped with electrostatic accelerators, accessing energetic light particles is crucial. For this purpose, selected nuclear reactions were introduced. In this research, primary proton, deuterium and helium-3 beams with energy less than 2 MeV were used for samples with a thickness of 1019 atom.cm-2 and the yield of reactions was obtained. The laboratory setup was designed in such a way that in addition to the access to the nuclear reaction products with a suitable yield, favorable conditions were provided for the extraction and transfer of the reaction products as well as their interaction with the sample. In these exothermic nuclear reactions, the yield is in the order of 106 particles and secondary proton and alpha particles with energies of 4 to18.5 MeV have been obtained. Also, the selected reactions are in accordance with the radiation protection protocols of similar laboratories.