Radiation Physics and Engineering
Year:2022 | Volume:3 | Issue:2|Papers Count:6

In this study, cold atmospheric pressure plasma jets for treatment application was studied with COMSOL Multiphysics by a finite element solver. The device operated with argon gas in atmospheric pressure which was supplied by an alternating current power supply. Effective plasma parameters for treatment such as electron density and temperature as well as electrical potential were investigated. Plasma parameters that affect treatment were determined by establishing a virtual laboratory before the experiment. Using this virtual laboratory, the plasma parameters with probable effects on the treatment can be determined before the experiment. The results showed that the electron density value was suitable for the therapeutic applications and the plasma temperature was in the allowable range for treatment.

In this research work, powder hydroxyapatite samples were synthesized using a solid-state reaction method to investigate the annealing effect. The crystal structure was carried out by XRD system produced data, and the Rietveld method using MAUD software. The samples were irradiated in different radiation absorbed doses up to 1500 Gy and their thermoluminescence properties including glow curve, response, fading effect and reproducibility were investigated from dosimetry point of view. The results showed that the annealing temperature significantly affects the crystal structure and thermoluminescence dosimetry response of hydroxyapatite samples, consequently. It was concluded that high temperature annealing process can lead to formation of ,-TCP crystal phase during the synthesis of hydroxyapatite. Percentage of this formed phase increases with rising the temperature, and finally leads to increasing of the thermoluminescence response. It was concludded that in the solid state reaction method to increasing the TL response, it is better to use high annealing temperature for the synthesis of hydroxyapatite sample.

In this experimental work, Polycarbonate/Bismuth Oxide (PC-Bi2O3) nanocomposites were prepared in various concentrations of 0, 10, 30, and 50 wt% with thicknesses of 1 mm and irradiated by a pure beta-emitter source of Sr-90. To fabricate the electrodes, copper sheets with thickness of 100 μ, m were attached to the top and bottom surfaces of the samples using the silver paste. Then, electric current as the dosimetry response, was measured at various dose rates ranging from 30 to 102 mSv. h−, 1 at a fixed voltage of 400 V using an electrometer. Results showed that increasing the Bi2O3 wt% led to improvement in the dosimetry response linearly at various dose rates. Also, the amounts of sensitivities for the samples of 0, 10, 30, and 50 wt% were measured as 20. 3, 19. 8, 28. 6, and 36. 7 nC. mSv−, 1. cm−, 3, respectively. Regarding the mechanism of beta interaction with a polymer-heavy metal oxide nanocomposite, the Bremsstrahlung radiation can be considered as a dominant effect.

Two main insulating gases of SF6 and N2/CO2 mixture are employed to increase voltage capability of electrostatic accelerators. SF6 offers more insulating capability, but environmental and technical disadvantages of SF6 makes usage of N2/CO2 mixture a desirable option. This paper aims to replace SF6 with N2/CO2 in design of a 500 kV/30 mA parallel-fed voltage multiplier. High-voltage section of the accelerator is a capacitive structure which in combination with rectifying elements, generates the accelerating high-voltage. The structure which is called Voltage Multiplier Capacitive Structure (VMCS) is designed and analyzed in this paper. The first structure is designed to employ SF6 as insulating gas (VMCS500). Then, the structure is modified to be capable of using N2/CO2 as insulating gas with lower breakdown voltage (VMCS500-m). The modified structure requires more complex mechanical manufacturing process, but offers the simplicity of using N2/CO2 mixture, the option of using the modified structure with superior SF6 gas, increasing the output voltage and beam energy. CST EM STUDIO was used for capacitance calculation and electric field analysis. LTSPICE was used for equivalent circuit analysis of the high voltage generating section.

In the present work performance of film badge as an alternative personal dosimeter for thermal neutrons is investigated. To do this, a cadmium-lead (Cd-Pb) filter with the same thickness as the tin-lead (Sn-Pb) filter is attached to the AERE/RPS badge. Since thermal neutrons are mixed with gamma rays, the dosimeter is irradiated by the Co-60 gamma rays standard field of Karaj Secondary Standard Dosimetry Lab as well as the mixed neutron-gamma field of the radiography beamline of Isfahan Miniature Neutron Source Reactor. In the both fields, ten personal dose-equivalent values between 0. 1 to 10 mSv are chosen. For any dose, three film badges are used and the net optical density is determined as the average of their optical densities. Finally, the calibration curves of the film badge are plotted to determine the dose-equivalent values. Obtained results reveal that film badge simultaneously determines the thermal neutrons and gamma rays dose fractions. Also, the thermal neutron doses are at most 50% different from the nominal values considered.

After some accidents like TMI and Fukushima Daiichi, the belief that nuclear fuels can safely and reliably be used up to 65 MW. d/kgU was revised, and many efforts have been devoted to develope different Accident Tolerant Fuel (ATF) concepts. In this study, an optimized cathodic arc PVD (ARC-PVD) coating condition, from the coating layer homogeneity and defect density point of views, have been obtained. Two coating material (i. e. pure Chromium and Chromium Nitride) with thicknesses up to 10 microns on typical VVER-1000 cladding tubes (Zr-1%Nb alloy) are developed. Presented SEM results approved improvements in coatings visual properties, and further modifications have been postponed until finalizing the performance examinations in normal operational as well as accidental conditions (LB LOCA). Eventyally, the general list of planned tests, from characterizations to mechanical and performance viewpoints, which are currently being carried out, is reported.