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| 1 | An improved semi-implicit direct kinetics method for transient analysis of nuclear reactors显示文摘Semi-implicit direct kinetics(SIDK)is an innovative method for the temporal discretization of neutronic equations proposed by J.Banfield.The key approximation of the SIDK method is to substitute a timeaveraged quantity for the fission source term in the delayed neutron differential equations.Hence,these equations are decoupled from prompt neutron equations and an explicit analytical representation of precursor groups is obtained,which leads to a significant reduction in computational cost.As the fission source is not known in a time step,the original study suggested using a constant quantity pertaining to the previous time step for this purpose,and a reduction in the size of the time step was proposed to lessen the imposed errors.However,this remedy notably diminishes the main advantage of the SIDK method.We discerned that if the original method is properly introduced into the algorithm of the point-implicit solver along with some modifications,the mentioned drawbacks will be mitigated adequately.To test this idea,a novel multigroup,multi-dimensional diffusion code using the finitevolume method and a point-implicit solver is developed which works in both transient and steady states.In addition to the SIDK,two other kinetic methods,i.e.,direct kinetics and higher-order backward discretization,are programmed into the diffusion code for comparison with the proposed model.The final code is tested at different conditions of two well-known transient benchmark problems.Results indicate that while the accuracy of the improved SIDK is closely comparable with the best available kinetic methods,it reduces the total time required for computation by up to 24%. | Roozbeh Vadi Kamran Sepanloo | 2019 | Nuclear Science and Techniques2019，30，11： | 3 |
| 2 | Loss of offsite power (LOOP) accident analysis by integration of deterministic and probabilistic approaches in Bushehr-1 VVER-1000/V446 nuclear power plant显示文摘The results of an accident analysis for the loss of offsite power(LOOP)scenario in a reference Bushehr-1 VVER-1000/V446 nuclear power plant(NPP)are presented in this paper.This study attempted to provide a better analysis of LOOP accident management by integrating deterministic and probabilistic approaches.The RELAP5 code was used to investigate the occurrence of specific thermal–hydraulic phenomena.The probabilistic safety assessment of the LOOP accident is presented using the SAPHIRE software.LOOP accident data were extracted from the Bushehr NPP final safety analysis reports and probabilistic safety analysis reports.A deterministic approach was used to reduce the core damage frequency in the probabilistic analysis of LOOP accidents.The probabilistic approach was used to better observe the philosophy of defense in depth and safety margins in the deterministic analysis of the LOOP accident.The results show that the integration of the two approaches in LOOP accident investigations improved accident control. | Mohsen Esfandiari Gholamreza Jahanfarnia Kamran Sepanloo Ehsan Zarifi | 2022 | Nuclear Science and Techniques2022，33，5： | 2 |
| 3 | Adsorptive separation of La(Ⅲ)from aqueous solution via the synthesized[Zn(bim)_(2)(bdc)]_(n) metal-organic framework显示文摘Lanthanum is one of the rare earth metals which due to specific chemio-physical properties,has wide applications in different industries.In this research,the ability of the synthesized metal-organic framework(MOF),[Zn(bim)_(2)(bdc)]_(n)(ZBB) for the removal of lanthanum ions from the aqueous stream was investigated in the batch and column processes.The synthesized MOF was characterized by using scanning electron microscopy(SEM),Brunauer-Emmett-Teller(BET),Fourier transform infrared spectroscopy(FTIR) and thermogravimetric analysis(TGA).The effect of pH on lanthanum ions adsorption was evaluated in the range from 1 to 7.Moreover,isothermal,kinetic,and thermodynamic parameters for adsorption of La(Ⅲ) ions onto the synthesized MOF were evaluated.The adsorption capacity of lanthanum ions onto the synthesized MOF was calculated to be about 130 mg/g.Thermodynamic studies demonstrate the endothermic and chemical nature of lanthanum adsorption,while kinetic studies suggest the pseudo-first-order of reaction.In column mode,the effect of solution flow rate passing through the fixed-bed was studied.Experimental data confirm that increasing the bed flow rate causes a decrease in the adsorption capacity of lanthanum ions on the synthesized MOF. | Sareh Ammari Allahyari Reza Saberi Kamran Sepanloo Ahmad Lashkari | 2021 | Journal of Rare Earths2021，39，6： | 1 |
| 4 | An improved porous media model for nuclear reactor analysis显示文摘In this study, two modifications are proposed to mitigate drawbacks of the conventional approach of using the ‘‘Porous Media Model''(PMM) for nuclear reactor analysis. In the conventional approach, whole reactor core simplifies to a single porous medium and also, the resistance coefficients that are essential to using this model are constant values. These conditions impose significant errors and restrict the applications of the model for many cases,including accident analysis. In this article, the procedures for calculating the coefficients are modified by introducing a practical algorithm. Using this algorithm will result in obtaining each coefficient as a function of mass flow rate.Furthermore, the method of applying these coefficients to the reactor core is modified by dividing the core into several porous media instead of one. In this method, each porous medium comprises a single fuel assembly. PMM with these two modifications is termed ‘‘multi-region PMM'' in this study. Then, the multi-region PMM is introduced to a new CFD-based thermo-hydraulic code that is specifically devised for combining with neutronic codes.The CITVAP code, which solves multi-group diffusion equations, is the selected as the neutronic part for this study. The resulting coupled code is used for simulation of natural circulation in a MTR. A new semi-analytic method,based on steady-state CFD analysis is developed to verify the results of this case. Results demonstrate considerable improvement, compared to the conventional approach. | Roozbeh Vadi Kamran Sepanloo | 2016 | Nuclear Science and Techniques2016，27，1： | 0 |
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