Hamid Rahimpour; HamidReza Mirzaei; Masoomeh Yarmohammadi Satri; Zafar Riazi Mobaraki
Abstract
A continuous-wave solid-state-based power amplifier is designed and simulated in this paper to work as an RF injector into an ECR ion source chamber. Employing a solid-state radio frequency power amplifier, instead of microwave tubes, leads to having higher efficiency, lower price, compact size, and ...
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A continuous-wave solid-state-based power amplifier is designed and simulated in this paper to work as an RF injector into an ECR ion source chamber. Employing a solid-state radio frequency power amplifier, instead of microwave tubes, leads to having higher efficiency, lower price, compact size, and longer lifetime. Also, a modular design can be achieved for designing higher output power by repeating lower power sources and combining them. The proposed solid-state source can deliver more than 200-watt power to the ion chamber with a single high-power transistor. The selected Doherty high-power transistor is internally matched to 50 ohms and doesn’t need a bias sequence circuit. Two gain stages are applied to drive the high-power transistor. The designed RF source is simulated using the Advanced Design System (ADS) based on the measured scattering parameters of components. Simulations show an output power of more than 57 dBm with a tunable frequency bandwidth from 2.3 to 2.5 GHz.
Milad Payandeh; Mahdi Sadeghi; Dylan Richeson; Somayeh Gholami
Abstract
It is important to have accurate information regarding the dose distribution for treatment planning and to accurately deposit that dose in the tissue surrounding the brachytherapy source. However, the practical measurement of dose distribution for various reasons is associated with several problems. ...
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It is important to have accurate information regarding the dose distribution for treatment planning and to accurately deposit that dose in the tissue surrounding the brachytherapy source. However, the practical measurement of dose distribution for various reasons is associated with several problems. In this study, 6711 I-125, Micro Selectron mHDR-v2r Ir-192, and Flexisource Co-60 sources were simulated using the MCNP5 Monte Carlo method. To simulate the sources, the exact geometric characteristics of each source, the material used in them, and the energy spectrum of each source were entered as input to the program, and finally, the dosimetric parameters including dose rate constant, radial dose function, and anisotropy function were calculated for considered seeds according to AAPM, TG-43 protocol recommendation. Results obtained for dosimetric parameters of dose rate constant, radial dose function, and anisotropy function for I-125, Ir-192, and Co-60 sources agreed with other studies. According to the good agreement obtained between the parameters of TG43 and other studies, now these datasets can be used as input in the treatment planning systems and to validate their calculations.
Ali Biganeh; Banin Shakeri Jooybari
Abstract
Compton scattering events are the main source of error on the peak counting during the Neutron Activation Analysis (NAA). The Compton suppressor system in instrumental NAA reduces the detection limit of the technique and leads to a data with a higher degree of precision. In this paper, a two-dimensional ...
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Compton scattering events are the main source of error on the peak counting during the Neutron Activation Analysis (NAA). The Compton suppressor system in instrumental NAA reduces the detection limit of the technique and leads to a data with a higher degree of precision. In this paper, a two-dimensional pseudo coincidence Compton suppressor system is presented for the NAA technique. The system is established based on a CAEN digitizer which directly records the pre-amplifier output signals of the two HPGe detectors. The recorded events in the list mode file are analyzed offline by a Matlab code and the correlated photopeak events are realized. The performance of the system for Compton suppression is tested by measuring the gamma lines of Ba-133 and Cs-137 standard sources. The results show that the presented technique provides the peak to Compton ratio up to 104 and can be an alternative for conventional Compton suppressor systems.
Abolfazl Shoghi; Seyed Ali Hosseini; Amir Saeed Shirani; Mehdi Zangian
Abstract
The pressurizer is a key equipment to ensure the safe operation of pressurized water reactor by maintaining the reactor coolant system pressure within allowed tolerances. Various pressure control systems (Pressurizer) are adopted in industrial applications to satisfy their characteristics. In accordance ...
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The pressurizer is a key equipment to ensure the safe operation of pressurized water reactor by maintaining the reactor coolant system pressure within allowed tolerances. Various pressure control systems (Pressurizer) are adopted in industrial applications to satisfy their characteristics. In accordance with the purpose of using nuclear facilities, Steam, Gas-Steam, and Gas Pressurizer (PRZ) have been used. In nuclear industry, the dynamic behavior of each PRZ is different. Peak pressure is one of the important parameters in choosing the type of PRZ. This study has been evaluated for the University of Wisconsin High-Pressure Critical Heat Flux (WHPCHF) facility as the base loop. Three PRZs are connected to the WHPCHF loop to evaluate their performance during the in-surge scenario. The Peak pressure of the three PRZs is evaluated during transients. The results showed that the use of the Non-condensable Gas (NCG) increases the peak pressure due to the lack of NCG condensation during transient conditions. The use of gas PRZ makes it possible to change the pressure quickly. Also, the pure gas PRZ has the highest peak pressure but has straightforward control logic. The gas PRZ is the best choice for small reactors and high-pressure test facilities.
Amir Charkhi; Parisa Zaheri; Amjad Sazgar; Iman Dehghan
Abstract
Since the production of tellurium hexafluoride gas requires the design of a suitable reactor system, so the study of tellurium oxide fluorination kinetics is of great importance. For this purpose, a novel laboratory system was designed and constructed to study the fluorination reactions by the volumetric ...
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Since the production of tellurium hexafluoride gas requires the design of a suitable reactor system, so the study of tellurium oxide fluorination kinetics is of great importance. For this purpose, a novel laboratory system was designed and constructed to study the fluorination reactions by the volumetric method. Fluorine gas was injected into the reactor containing a tellurium oxide pellet, and the reaction was studied by following the changes in pressure of the gas phase using a pressure transmitter instrument. In this volumetric system, the kinetic parameters of the reaction between tellurium oxide pellet and fluorine gas have been derived for a pressure range of 137.9 and 181.2 kPa by monitoring the gas phase pressure. The reaction temperature was adjusted to 204±1 ◦C using a heater. The results showed that the fluorination reaction of tellurium oxide is a first-order reaction. The reaction rate constant is calculated to be 6.86 × 10-4 s-1.
Akbar Abdi Saray; Hossein Zaki Dizaji; Mortaza Taheri Balanoji
Abstract
To monitor personal safety in the fields of biomedical and health physics, it is necessary to be aware of radiation doses to protect the health and safety of persons. Radiation protection quantities such as air kerma, ambient dose equivalent, and exposure dose rate are obtained by the measured spectrum ...
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To monitor personal safety in the fields of biomedical and health physics, it is necessary to be aware of radiation doses to protect the health and safety of persons. Radiation protection quantities such as air kerma, ambient dose equivalent, and exposure dose rate are obtained by the measured spectrum to determine energy-dependent conversion coefficients/factors. This study aims to obtain and compare an ambient dose equivalent to H∗(10) from the measured gamma-ray spectra by the NaI(Tl) scintillation detector using two various methods. The first method, which is based on the detector response function to find the conversion function, is called the G(E) method. The second method is subdividing the measured gamma-ray spectra into the multiple energy bins, and then obtaining the ambient dose equivalent by using conversion coefficient functions (ω(E)), which were determined by the conversion coefficients (ωi) of each energy bin for three energy intervals of ≤185 keV, 185 to 850 keV, and ≥850 keV. To calculate the detector response matrix and the conversion coefficients of each region of energy, the Monte Carlo simulation code was used for the quasi-mono energetic gamma radiation sources and the synthetic spectra. The results indicate that using the technique based on subdividing the measured spectrum into multiple energy bins helps to avoid the inverse detector response matrix dimension limitations that occur in the G(E) method and also have a lower error percentage in the dose quantity calculation. Consequently, NaI(Tl) scintillation detector has an excellent potential to replace the classical dose rate instruments, i.e. Geiger-Muller, for the early warning of environmental radiation monitoring.
