The Experts below are selected from a list of 189 Experts worldwide ranked by ideXlab platform
Khorshed Ahmad Kabir - One of the best experts on this subject based on the ideXlab platform.
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Study on the Positive Step Reactivity Insertion Effect on Reactor Period in BAEC TRIGA Mark-II Research Reactor
2018 International Conference on Innovation in Engineering and Technology (ICIET), 2018Co-Authors: Nazmul Hossain, Md. Abdul Malek Soner, Md. Hossain Sahadath, Md. Mahidul Haque Prodhan, Khorshed Ahmad KabirAbstract:The behavior of Reactor Period in response to any sudden change in reactivity is very important for nuclear Reactor control. In this study, experiments have been performed to analyze the effects of positive step reactivity insertion on Reactor Period. The 3 MW BAEC TRIGA Mark-II research Reactor was subjected to positive step reactivity insertion for initial power of 1 kW and 100 kW with continuous recording of change in Reactor power level. The Reactor Period is calculated for different positive reactivity and a comparison is shown how the initial power affects the Reactor Period. Reactor Period shows significant variations due to reactivity insertion at low initial power. The difference between the theoretical and experimental value of Reactor Period was greater for low reactivity insertion. The results of this research work will play a crucial role to ensure the safe and reliable nuclear Reactor operation.
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Measurement and Comparison of Control Rod Worth of BTRR using Inhour Equation and Period reactivity conversion table
Journal of Bangladesh Academy of Sciences, 2017Co-Authors: Iqbal Hosan, Mam Soner, Khorshed Ahmad KabirAbstract:In a nuclear Reactor, control rod is a very essential part and plays the elementary role in the Reactor control during Reactor start up, normal power operation, experimental research and shutdown. To perform all these operations safely, knowledge of differential and integral worth of the control rod is mandatory. In this study, the differential and integral worth curve of all control rods of BAEC TRIGA Research Reactor (BTRR) have been determined by using the positive Period method. Reactor Period was measured from 1.5 folding time, doubling time, 5 folding time respectively; and in the above three cases reactivity has also been calculated from INHOUR equation and Period reactivity conversion table. The total worth of all control rods of BTRR are measured as 14.888 $, 14.672 $, 14.348 $ from INHOUR equation and 13.978 $, 13.672 $, 13.357 $ from Period reactivity conversion table for 1.5 folding time, doubling time and 5 folding time respectively. The measured reactivity has also been compared with the previously measured reactivity and due to fuel burn up of the Reactor expected lower values were observed. Journal of Bangladesh Academy of Sciences, Vol. 41, No. 1, 95-103, 2017
Andrea Zoia - One of the best experts on this subject based on the ideXlab platform.
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Chaos in eigenvalue search methods
Annals of Nuclear Energy, 2018Co-Authors: Davide Mancusi, Andrea ZoiaAbstract:Abstract Eigenvalue searches for multiplying systems emerge in several applications, encompassing the determination of the so-called alpha eigenvalues associated to the asymptotic Reactor Period and the adjustment of albedo boundary conditions or buckling in assembly calculations. Such problems are usually formulated by introducing a free parameter into a standard power iteration, and finding the value of the parameter that makes the system exactly critical. The corresponding parameter is supposed to converge to the sought eigenvalue. In this paper we show that the search for the critical value of the parameter might fail to converge for deep sub-critical systems: in this case, the search algorithm may undergo a series of Period doubling bifurcations (leading to a multiplicity of solutions) instead of converging to a fixed point, or it may even crash. This anomalous behaviour is explained in terms of the mathematical structure of the search algorithm, which is shown to be closely related to the well-known logistic map for a few relevant applications illustrated in the context of the rod model. The impact of these findings for real-life applications is discussed, and possible remedies are finally suggested.
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Analysis of dynamic reactivity by Monte Carlo methods: The impact of nuclear data
Annals of Nuclear Energy, 2017Co-Authors: Andrea Zoia, Cédric Jouanne, Patricia Siréta, Pierre Leconte, George Braoudakis, Lindee WongAbstract:Abstract We compute the dynamic reactivity of several Reactor configurations by resorting to Monte Carlo simulation. The adjoint-weighted kinetics parameters are first determined by the Iterated Fission Probability (IFP) method, together with precursor decay constants, and the reactivity is then estimated by the inhour equation. When literature values are available for the reactivity as a function of the asymptotic Reactor Period, comparison with the Monte Carlo simulation findings allows validating the IFP algorithm and at the same time probing the accuracy of the nuclear data libraries used in numerical simulations. For our calculations we resort to the T ripoli-4 ® Monte Carlo code, developed at CEA, where IFP methods have been recently implemented. We perform a detailed analysis of the IPEN/MB-01 core, the SPERT III E-core, and the SPERT IV D-12/25 core, for which benchmark-quality Reactor specifications have been published. We single out some systematic discrepancies between computed and measured core reactivity that might mirror possible inconsistencies in nuclear data libraries.
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Generalized Iterated Fission Probability for Monte Carlo eigenvalue calculations
Annals of Nuclear Energy, 2017Co-Authors: Nicholas Terranova, Andrea ZoiaAbstract:Abstract The so-called Iterated Fission Probability (IFP) method has provided a major breakthrough for the calculation of the adjoint flux and more generally of adjoint-weighted scores in Monte Carlo eigenvalue calculations. So far, IFP has been exclusively devoted to the analysis of the standard k -eigenvalue equation, by resorting to a formal identification between the adjoint fundamental eigenmode φ k † and the neutron importance I k . In this work, we extend the IFP method to the α -eigenvalue equation, enabling the calculation of the adjoint fundamental eigenmode φ α † and the associated adjoint-weighted scores, including kinetics parameters. Such generalized IFP method is first verified in a simple two-group infinite medium transport problem, which admits analytical solutions. Then, α -adjoint-weighted kinetics parameters are computed for a few Reactor configurations by resorting to the Monte Carlo code Tripoli-4 ®, and compared to the k -adjoint-weighted kinetics parameters obtained by the standard IFP. The algorithms that we have developed might be of interest in the interpretation of reactivity measurements, in the context of Reactor Period calculations by Monte Carlo simulation.
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Reactor physics analysis of the SPERT III E-core with Tripoli-4®
Annals of Nuclear Energy, 2016Co-Authors: Andrea Zoia, Emeric BrunAbstract:Abstract In this paper we detail a Monte Carlo model for the SPERT III E-core and we illustrate the simulation results obtained for the Reactor physics parameters (including the effective multiplication factor, the reactivity worth of the core components and the kinetics parameters) by resorting to the production code T ripoli -4®. We have considered three Reactor configurations, namely, initial core loading, zero cold power and hot zero power in stationary conditions, based on the large database of available experimental measurements. This analysis is aimed at establishing a firm background for the future investigation of the time-dependent behavior of the E-core under reactivity excursions by resorting to Reactor Period calculations and dynamic Monte Carlo methods.
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monte carlo methods for Reactor Period calculations
Annals of Nuclear Energy, 2015Co-Authors: Andrea Zoia, Emeric Brun, Frederic Damian, Fausto MalvagiAbstract:Abstract Several technological issues, such as Reactor start-up analysis or kinetics studies of accelerator-driven systems, demand the asymptotic time behaviour of neutron transport to be assessed. Typically, this amounts to solving an eigenvalue equation associated to the Boltzmann operator, whose precise nature depends on whether delayed neutrons are taken into account. The inverse of the dominant eigenvalue can be physically interpreted as the asymptotic Reactor Period. In this work, we propose a Monte Carlo method for determining the dominant alpha eigenvalue of the Boltzmann operator and the associated fundamental mode for arbitrary geometries, materials, and boundary conditions. Extensive verification tests of the algorithm are performed, and Monte Carlo calculations are finally validated against Reactor Period measurements carried out at the ORPHEE facility of CEA/Saclay.
Tadashi Narabayashi - One of the best experts on this subject based on the ideXlab platform.
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sensitivity analysis for Reactor Period induced by positive reactivity using one point adjoint kinetic equation
Nuclear Data Sheets, 2014Co-Authors: Go Chiba, Masashi Tsuji, Tadashi NarabayashiAbstract:Abstract In order to better predict a kinetic behavior of a nuclear fission Reactor, an improvement of the delayed neutron parameters is essential. The present paper specifies important nuclear data for a Reactor kinetics: Fission yield and decay constant data of 86 Ge, some bromine isotopes, 94 Rb, 98 m Y and some iodine isotopes. Their importance is quantified as sensitivities with a help of the adjoint kinetic equation, and it is found that they are dependent on an inserted reactivity (or a Reactor Period). Moreover, dependence of sensitivities on nuclear data files is also quantified using the latest files. Even though the currently evaluated data are used, there are large differences among different data files from a view point of the delayed neutrons.
J.r. Taylor - One of the best experts on this subject based on the ideXlab platform.
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The central void reactivity in the Oak Ridge National Laboratory enriched uranium (93.2) metal sphere
Nuclear Science and Engineering, 1998Co-Authors: John T. Mihalczo, J.j. Lynn, J.r. TaylorAbstract:The reactivity worth of a central void region in the Oak Ridge National Laboratory (ORNL) unmoderated and unreflected uranium (93.20 wt% {sup 235}U) metal sphere was obtained by replacement measurements in a small (0.460-cm-diam) central spherical region in this 3.4420-in.-radius sphere. The measured central void region worth was 9.165 {+-} 0.023 {cents} using the delayed neutron parameters of Keepin, Wimett, and Zeigler to obtain the reactivity from the measured stable Reactor Periods. This value is slightly larger than measurements for GODIVA I with larger cylindrical samples of uranium (93.70 wt% {sup 235}U) in the center: 135.50 {+-} 0.12 {cents}/mol for GODIVA I and 138.05 {+-} 0.34 {cents}/mol for the ORNL sphere measurements. The difference could be due to sample size effect. The central worth was also calculated by neutron transport theory methods to be 6.02 {+-} 0.01 {times} 10{sup {minus}4} {Delta}k. The measured and calculated values are related by the effective delayed neutron fraction. The value of the effective delayed neutron fraction obtained in this way from the ORNL sphere is 0.00657 {+-} 0.00002, which is in excellent agreement with that obtained from GODIVA I measurements, where the effective delayed neutron fraction was determined as the increment between delayed andmore » prompt criticality and was 0.0066. From these ORNL measurements, using the delayed neutron parameters of ENDF-B/VI to obtain the reactivity from the stable Reactor Period measurements, the central void worth is 7.984 {+-} 0.021 {cents}, and the inferred effective delayed neutron fraction is 0.00754. These values are 14.2% higher than those obtained from use of the Keepin, Wimett, and Zeigler delayed neutron data and produce a value of effective delayed neutron fraction in disagreement with GODIVA I measurements, thus questioning the usefulness of the six-group delayed neutron parameters (fast fission) of uranium from ENDF-B/VI for obtaining the reactivity from the measured Reactor Period using the Inhour equation.« less
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The central void reactivity in the Oak Ridge enriched uranium (93.2) metal sphere
1997Co-Authors: J.t. Milhalczo, J.j. Lynn, J.r. TaylorAbstract:The central reactivity void worth was measured in the Oak Ridge unmoderated and unreflected uranium (93.20 wt% {sup 235}U) metal sphere by replacement measurements in a small (0.460-cm-diam) central spherical region in an 8.7427-cm-radius sphere. The central void worth was 9.165 {+-} 0.023 cents using the delayed neutron relative abundances and decay constants of Keepin, Wimett, and Zeigler to obtain the reactivity in cents from the stable Reactor Period measurements using the Inhour equation. This value is slightly larger than measurements with GODIVA 1 with larger cylindrical samples of uranium (93.70 wt% {sup 235}U) in the center: 135.50 {+-} 0.12 cents/mole for GODIVA 1 and 138.05 {+-} 0.34 cents/mole for the Oak Ridge sphere measurements, and the difference could be due to sample size effect. The central worth in {Delta}k units was calculated by neutron transport theory methods to be 6.02 {+-} 0.01 x 10{sup {minus}4} {Delta}k. The measured and calculated values are related by the effective delayed neutron fraction. The value of the effective delayed neutron fraction obtained in this way from the Oak Ridge sphere is 0.00657 {+-} 0.00002, which is in excellent agreement with that obtained from GODIVA 1 measurements, where the effective delayed neutron fraction was determined as the increment between delayed and prompt criticality and was 0.0066. From these Oak Ridge measurements, using the delayed neutron parameters of ENDF-B/VI to obtain the reactivity from the stable Reactor Period measurements, the central void worth is 7.984 {+-} 0.021 cents, and the inferred effective delayed neutron fraction is 0.00754. This central void worth and effective delayed neutron fractions are 14.2% higher than those obtained from use of the Keepin et al. delayed neutron data and produce a value of delayed neutron fraction in disagreement with GODIVA 1 measurements, thus questioning the usefulness of the relative abundances and decay constants of the six-group delayed neutron parameters of ENDF-B/VI for uranium for obtaining the reactivity from the measured Reactor Period using the Inhour equation.
Yasushi Nauchi - One of the best experts on this subject based on the ideXlab platform.
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attempt to estimate Reactor Period by natural mode eigenvalue calculation
International Conference on Supercomputing, 2014Co-Authors: Yasushi NauchiAbstract:A calculation technique of the inverse Reactor Period of a perturbed state is investigated. That is achieved by solving the natural mode equation which expresses the neutron balance where the core power changes exponentially with time. The technique is implemented into the MCNP-5 code and tested for perturbed states. The convergence of the calculated inverse Reactor Period is observed and the ratio of the converged values to experimental data in literature ranges 0.93~1.28. The error would be mainly attributed to estimations of the neutron balance between production and annihilation.
