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- 검색키워드
- 저자 : A. Mirvakili (검색결과 5 건)
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Z. GHOLAMZADEH,S.A.H. FEGHHI,S.M. MIRVAKILI,A. JOZE-VAZIRI,M. ALIZADEH 한국원자력학회 2015 Nuclear Engineering and Technology Vol.47 No.7
The use of subcritical aqueous homogenous reactors driven by accelerators presents anattractive alternative for producing 99Mo. In this method, the medical isotope productionsystem itself is used to extract 99Mo or other radioisotopes so that there is no need toirradiate common targets. In addition, it can operate at much lower power compared to atraditional reactor to produce the same amount of 99Mo by irradiating targets. In this study,the neutronic performance and 99Mo, 89Sr, and 131I production capacity of a subcriticalaqueous homogenous reactor fueled with low-enriched uranyl nitrate was evaluated usingthe MCNPX code. A proton accelerator with a maximum 30-MeV accelerating power wasused to run the subcritical core. The computational results indicate a good potential for themodeled system to produce the radioisotopes under completely safe conditions because ofthe high negative reactivity coefficients of the modeled core. The results show thatapplication of an optimized beam window material can increase the fission power of theaqueous nitrate fuel up to 80%. This accelerator-based procedure using low enricheduranium nitrate fuel to produce radioisotopes presents a potentially competitive alternativein comparison with the reactor-based or other accelerator-based methods. This systemproduces ~1,500 Ci/wk (~325 6-day Ci) of 99Mo at the end of a cycle.
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M.R. Rahimpour,A. Mirvakili 한국공업화학회 2013 Journal of Industrial and Engineering Chemistry Vol.19 No.2
In this study, decalin and hydrogen looping approach is proposed in optimized thermally coupled membrane ternary reactors in gas-to-liquid technology (GTL). This novel configuration is named thermally coupled membrane ternary reactor (TCMTR), in which decalin dehydrogenation reaction is coupled with Fischer–Tropsch synthesis (FTS) reactions. Three different reactors are fabricated and integrated with membrane reactor where decalin and hydrogen are produced and utilized simultaneously. Under the optimized operating conditions of TCMTR via differential evolution method,decalin can be properly utilized in this novel configuration as a hydrogen carrier and the required decalin can be produced within the continuous loop and a slight amount of decalin is required for supplementation. 4.77% of the produced hydrogen in the first reactor is utilized in FTS reactions in the second reactor and the remaining 95.23% is utilized in hydrogenation reaction of naphthalene in the third reactor which leads to decalin production as a reactant of the first reactor. A comparison is made between the performances of optimized TCMTR (OTCMTR), conventional tubular reactor (CR) and thermally coupled membrane dual-type reactor (TCMDR). Significant decrease in decalin consumption rate can be achieved in this new scheme, and the hydrogen storage problem and no requirement for injection of fresh feed in each process. The results demonstrate the superiority of OTCMTR to all previously proposed configurations. Furthermore, the hydrogen storage problem is properly addressed by OTCMTR and significant decrease in decalin consumption rate can be achieved in this new scheme.
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A. Mirvakili,F. Samimi,A. Jahanmiri 한국공업화학회 2014 Journal of Industrial and Engineering Chemistry Vol.20 No.4
In thermal decomposition process, ammonium nitrate decomposition takes place in fluidized bed reactor (FR) and nitrogen oxide (NOx), as an undesirable product is produced in high temperatures. In this study, two novel configurations named membrane fluidized bed reactor (MFR) and free air membrane fluidized bed reactor (AMFR) is proposed to reduce NOx emission. Models predictions are validated by experimental data presented by Bhowmick et al. The results show 16% and 7% decrease in NOx concentration in AMFR and MFR respectively, compared with FR. Reduction of NOx emission and enhancement of ammonium nitrate conversion, demonstrate superiority of AMFR to previous configurations.
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Effect of gamma irradiation on the critical heat flux of nano-coated surfaces
A. Rahimian,H. Kazeminejd,H. Khalaf,A. Akhavan,M. Mirvakili 한국원자력학회 2020 Nuclear Engineering and Technology Vol.52 No.10
An anodic electrophoretic deposition (EPD) technique is used to create a uniform TiO2 thin film coating on boiling thin steel plates (1.1 mm by 90 mm). All of the effective parameters except time of the EPD method are kept constant. To investigate the effect of gamma irradiation on the critical heat flux (CHF), the test specimens were irradiated in a gamma cell to different doses ranging from 100 to 300 kGy, and then SEM and BET analysis were performed. For each coated specimen, the contact angle and capillary length were measured. The specimens were then tested in a boiling pool for CHF and boiling heat transfer coefficient. It was observed that irradiation significantly decreases the maximum pore diameter while it increases the porosity, pore surface area and pore volume. These surface modifications due to gamma irradiation increased the CHF of the nano-coated surfaces compared to that of the unirradiated surfaces. The heat transfer coefficient (HTC) of the nano-coated surfaces irradiated at 300 kGy increased from 83 to 160 kW/(m2 K) at 885 kW/m2 wall heat flux by 100%. The CHF of the irradiated (300 kGy) and unirradiated surfaces are 2035 kW/m2 and 1583 kW/m2, respectively, an increase of nearly 31%.
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Z. Gholamzadeh, E. Bavarnegin,E. Bavarnegin,M.Lamehi Rachti,S.M. Mirvakili,M.H.Choopan Dastjerdi,H. Ghods,A. Jozvaziri,M. Hosseini 한국원자력학회 2018 Nuclear Engineering and Technology Vol.50 No.1
The neutron powder diffractometer (NPD) is used to study a variety of technologically important andscientifically driven materials such as superconductors, multiferroics, catalysts, alloys, ceramics, cements,colossal magnetoresistance perovskites, magnets, thermoelectrics, zeolites, pharmaceuticals,etc. Monte Carloebased codes are powerful tools to evaluate the neutronic behavior of the NPD. In thepresent study, MCNPX 2.6.0 and Vitess 3.3a codes were applied to simulate NPD facilities, which couldbe equipped with different optic devices such as pyrolytic graphite or neutron chopper. So, the MonteCarloebased codes were used to simulate the NPD facility of the 5 MW Tehran Research Reactor. Thesimulation results were compared to the experimental data. The theoretical results showed goodconformity to experimental data, which indicates acceptable performance of the Vitess 3.3a code in theneutron optic section of calculations. Another extracted result of this work shows that application ofneutron chopper instead of monochromator could be efficient to keep neutron flux intensity higherthan 106 n/s/cm2 at sample position.
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