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- 저자 : Ochbelagh, Dariush Rezaei (검색결과 3 건)
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Thermal neutron albedo and flux for different geometries neutron guide
S. Azimkhani,D. Rezaei Ochbelagh,F. Zolfagharpour 한국원자력학회 2019 Nuclear Engineering and Technology Vol.51 No.4
This paper presents a study on thermal neutron reflection properties of neutron guide for cylinder,spindle, elliptic and parabolic geometries using 241Am-Be neutron source (5.2 Ci) and BF3 detector,whereas neutron guide is important instrument for transportation of neutrons. To this goal, the requiredinner and outer radii of neutron guide have been calculated to achieve the highest guided thermalneutron flux based on MCNPX Monte Carlo code. The maximum flux of cylinder geometry with a length50 cm has been obtained at an inner radius 9 cm and an outer radius 21 cm. Also, the maximum value ofthermal neutron albedo is 0.46 ± 0.001 at 12 cm thickness of parabolic guide.
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Mehran Vagheian,Dariush Rezaei Ochbelagh,Morteza Gharib 한국원자력학회 2019 Nuclear Engineering and Technology Vol.51 No.5
A new moving-mesh Finite Volume Method (FVM) for the efficient solution of the two-dimensionalneutron diffusion equation is introduced. Many other moving-mesh methods developed to solve theneutron diffusion problems use a relatively large number of sophisticated mathematical equations, andso suffer from a significant complexity of mathematical calculations. In this study, the proposed methodis formulated based on simple mathematical algebraic equations that enable an efficient mesh movementand CV deformation for using in practical nuclear reactor applications. Accordingly, a computationalframework relying on a new moving-mesh FVM is introduced to efficiently distribute the meshesand deform the CVs in regions with high gradient variations of reactor power. These regions of interestare very important in the neutronic assessment of the nuclear reactors and accordingly, a higher accuracyof the power densities is required to be obtained. The accuracy, execution time and finally visual comparison of the proposed method comprehensivelyinvestigated and discussed for three different benchmark problems. The results all indicated a higheraccuracy of the proposed method in comparison with the conventional fixed-mesh FVM.
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Mahmoudi, Sayyed Mostafa,Rad, Milad Mansouri,Ochbelagh, Dariush Rezaei Korean Nuclear Society 2021 Nuclear Engineering and Technology Vol.53 No.11
One of the important parts of the in-core fuel management is loading pattern optimization (LPO). The loading pattern optimization as a reasonable design of the in-core fuel management can improve both economic and safe aspects of the nuclear reactor. This work proposes the hybrid of fuzzy logic controller with harmony search algorithm (HS) for loading pattern optimization in a pressurized water reactor. The music improvisation process to find a pleasing harmony is inspiring the harmony search algorithm. In this work, the adjustment of the harmony search algorithm parameters such as the bandwidth and the pitch adjustment rate are increasing performance of the proposed algorithm which is done through a fuzzy logic controller. Hence, membership functions and fuzzy rules are designed to improve the performance of the HS algorithm and achieve optimal results. The objective of the method is finding an optimum core arrangement according to safety and economic aspects such as reduction of power peaking factor (PPF) and increase of effective multiplication factor (Keff). The proposed approach effectiveness has been tried in two cases, Michalewicz's bivariate function problem and NEACRP LWR core. The results show that by using fuzzy harmony search algorithm the value of the fitness function is improved by 15.35%. Finally, with regard to the new solutions proposed in this research it could be used as a trustworthy method for other optimization issues of engineering field.
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