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RISS 인기검색어
- 검색키워드
- 저자 : Jahanfarnia, Gh. (검색결과 4 건)
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Zare, Nafiseh,Jahanfarnia, Gholamreza,Khorshidi, Abdollah,Soltani, Jamshid Korean Nuclear Society 2020 Nuclear Engineering and Technology Vol.52 No.9
In this study, a fractional order proportional integral derivative (FOPID) controller is designed to create the reference power trajectory and to conquer the uncertainties and external disturbances. A fractional nonlinear model was utilized to describe the nuclear reactor dynamic behaviour considering thermal-hydraulic effects. The controller parameters were tuned using optimization method in Matlab/Simulink. The FOPID controller was simulated using Matlab/Simulink and the controller performance was evaluated for Hard variation of the reference power and compared with that of integer order a proportional integral derivative (IOPID) controller by two models of fractional neutron point kinetic (FNPK) and classical neutron point kinetic (CNPK). Also, the FOPID controller robustness was appraised against the external disturbance and uncertainties. Simulation results showed that the FOPID controller has the faster response of the control attempt signal and the smaller tracking error with respect to the IOPID in tracking the reference power trajectory. In addition, the results demonstrated the ability of FOPID controller in disturbance rejection and exhibited the good robustness of controller against uncertainty.
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Ghafour Ahmad Khanbeigi,Gholamreza Jahanfarnia,Naser Mansour Sharifloo,Mohamad Kazem Sheikh-el-Eslami,Kaveh Karimi 대한전기학회 2020 Journal of Electrical Engineering & Technology Vol.15 No.5
In this paper a close solution is presented to determine the trade-off between cost and safety to cope with station blackout (SBO) in Pressurized Water Reactors (PWRs). To compute the profi t of each generation unit, a Supply Function Equilibrium (SFE) model swhich considers carbon tax is used in a uniform electricity market. A hierarchical heuristic method is applied for decision making on safety improvement of Nuclear Power Plants (NPPs). In this method the break-even point is used as a criterion to make a decision on comparing cost of safety improvement and profi t of NPP in a deregulated electricity market. This method is applied in a case of adding an Emergency Water Supply (EWS) and an Emergency Diesel Generator (EDG) to a NPP where impacts of its investment cost and its profi t are investigated. The achieved results show that the break-even point of investment cost and net profi t of the NPP by adding the EDG is one month later than NPP with addition of EWS.
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Mokhtari, K.,Kheradmand Saadi, M.,Ahmadpanahi, H.,Jahanfarnia, Gh. Korean Nuclear Society 2021 Nuclear Engineering and Technology Vol.53 No.9
The concrete is considered as an important radiation shielding material employed widely in nuclear reactors, particle accelerators, laboratory hot cells and other different radiation sources. The present research is dedicated to the shielding properties study of the ordinary concrete reinforced with different weight fractions of lead oxide micro/nano particles. Lead oxide particles were fabricated by chemical synthesis method and their properties including the average size, morphological structure, functional groups and thermal properties were characterized by XRD, FESEM-EDS, FTIR and TGA analysis. The gamma ray mass attenuation coefficient of concrete composites has been calculated and measured by means of the Monte Carlo simulation and experimental methods. The simulation process was based on the use of MCNP Monte Carlo code where the mass attenuation coefficient (μ/ρ) has been calculated as a function of different particle sizes and filler weight fractions. The simulation results showed that the employment of the lead oxide filler particles enhances the mass attenuation coefficient of the ordinary concrete, drastically. On the other hand, there are approximately no differences between micro and nano sized particles. The mass attenuation coefficient was increased by increasing the weight fraction of nanoparticles. However, a semi-saturation effect was observed at concentrations more than 10 wt%. The experimental process was based on the fabrication of concrete slabs filled by different weight fractions of nano lead oxide particles. The mass attenuation coefficients of these slabs were determined at different gamma ray energies using <sup>22</sup>Na, <sup>137</sup>Cs and <sup>60</sup>Co sources and NaI (Tl) scintillation detector. The experimental results showed that the HVL parameter of the ordinary concrete reinforced with 5 wt% of nano PbO particles was reduced by 64% at 511 keV and 48% at 1332 keV. Reasonable agreement was obtained between simulation and experimental results and showed that the employment of nano PbO particles is more efficient at low gamma energies up to 1Mev. The proposed concrete is less toxic and could be prepared in block form instead of toxic lead blocks.
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Mehdi Dehjourian,Reza Sayareh,Mohammad Rahgoshay,Gholamreza Jahanfarnia,Amir Saied Shirani 한국원자력학회 2016 Nuclear Engineering and Technology Vol.48 No.5
Hydrogen release during severe accidents poses a serious threat to containment integrity. Mitigating procedures are necessary to prevent global or local explosions, especially in large steel shell containments. The management of hydrogen safety and prevention of overpressurization could be implemented through a hydrogen reduction system and spray system. During the course of the hypothetical large break loss-of-coolant accident in a nuclear power plant, hydrogen is generated by a reaction between steamand the fuel-cladding inside the reactor pressure vessel and also core concrete interaction after ejection of melt into the cavity. The MELCOR 1.8.6 was used to assess core degradation and containment behavior during the large break loss-of-coolant accident without the actuation of the safety injection system except for accumulators in Beznau nuclear power plant. Also, hydrogen distribution in containment and performance of hydrogen reduction system were investigated.
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