The Experts below are selected from a list of 78 Experts worldwide ranked by ideXlab platform
Peter Moller - One of the best experts on this subject based on the ideXlab platform.
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status of Delayed Neutron Precursor data half lives and Neutron emission probabilities
Progress in Nuclear Energy, 2002Co-Authors: B Pfeiffer, K L Kratz, Peter MollerAbstract:Abstract We present in this paper a compilation of the present status of experimental Delayed-Neutron Precursor data; i.e. β-decay half-lives ( T 1/2 ) and Neutron emission probabilities ( P n ) in the fission-product region (27 ≤ Z ≤ 57). These data are compared to two model predictions of substantially different sophistication: (i) an update of the empirical Kratz-Herrmann formula (KHF), and (ii) a unified macroscopic-microscopic model within the quasi-particle random-phase approximation (QRPA). Both models are also used to calculate so far unknown T 1/2 and P n values up to Z = 63. A number of possible refinements in the microscopic calculations are suggested to further improve the nuclear-physics foundation of these data for reactor and astrophysical applications.
B Pfeiffer - One of the best experts on this subject based on the ideXlab platform.
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status of Delayed Neutron Precursor data half lives and Neutron emission probabilities
Progress in Nuclear Energy, 2002Co-Authors: B Pfeiffer, K L Kratz, Peter MollerAbstract:Abstract We present in this paper a compilation of the present status of experimental Delayed-Neutron Precursor data; i.e. β-decay half-lives ( T 1/2 ) and Neutron emission probabilities ( P n ) in the fission-product region (27 ≤ Z ≤ 57). These data are compared to two model predictions of substantially different sophistication: (i) an update of the empirical Kratz-Herrmann formula (KHF), and (ii) a unified macroscopic-microscopic model within the quasi-particle random-phase approximation (QRPA). Both models are also used to calculate so far unknown T 1/2 and P n values up to Z = 63. A number of possible refinements in the microscopic calculations are suggested to further improve the nuclear-physics foundation of these data for reactor and astrophysical applications.
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status of Delayed Neutron Precursor data half lives and Neutron emission probabilities
arXiv: Nuclear Experiment, 2001Co-Authors: B Pfeiffer, K L Kratz, P MoellerAbstract:We present in this paper a compilation of the present status of experimental Delayed-Neutron Precursor data; i.e. beta-decay half-lives (T_1/2) and Neutron emission probabilities (P_n) in the fission-product region (27 <= Z <= 57). These data are compared to two model predictions of substantially different sophistication: (i) an update of the empirical Kratz-Herrmann formula (KHF), and (ii) a unified macroscopic-microscopic model within the quasi-particle random-phase approximation (QRPA). Both models are also used to calculate so far unknown T_1/2 and P_n values up to Z=63. A number of possible refinements in the microscopic calculations are suggested to further improve the nuclear-physics foundation of these data for reactor and astrophysical applications.
H Rouch - One of the best experts on this subject based on the ideXlab platform.
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development of an openfoam model for the molten salt fast reactor transient analysis
Chemical Engineering Science, 2014Co-Authors: Manuele Aufiero, Antonio Cammi, O Geoffroy, Mario Losa, Lelio Luzzi, Marco Enrico Ricotti, H RouchAbstract:Abstract In the paper, the development of a multiphysics model for the transient analysis of non-moderated Molten Salt Reactors is discussed. Particular attention is devoted to the description of the adopted time integration and physics coupling strategies. The proposed model features the adoption of an implicit Runge–Kutta scheme and the coupling among Neutron diffusion, Reynolds-Averaged Navier–Stokes equations for mass and momentum conservation, and energy and Delayed Neutron Precursor balance equations, in order to accurately catch thermal feedbacks on Neutronics. The solver is aimed at performing fast-running simulations of the full-core three-dimensional Molten Salt Fast Reactor geometry. The Neutronics modelling is assessed against Monte Carlo simulations and the results of a simplified case study are compared to those from multiphysics tools previously developed. As an example of the capability of the model, an unprotected MSFR single pump failure accidental scenario is simulated and discussed. The main purpose of the present model is to serve as fast-running computational tool in the phase of design optimization of fuel loop components. More in general, it is of valuable help in the study of reactor physics of circulating-fuel systems.
G R Ansarifar - One of the best experts on this subject based on the ideXlab platform.
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core power control of the fast nuclear reactors with estimation of the Delayed Neutron Precursor density using sliding mode method
Nuclear Engineering and Design, 2016Co-Authors: G R Ansarifar, M N Nasrabadi, R HassanvandAbstract:Abstract In this paper, a nonlinear controller using sliding mode method which is a robust nonlinear controller is designed to control a fast nuclear reactor. The reactor core is simulated based on the point kinetics equations and one Delayed Neutron group. Considering the limitations of the Delayed Neutron Precursor density measurement, a sliding mode observer is designed to estimate it and finally a sliding mode control based on the sliding mode observer is presented. The stability analysis is given by means Lyapunov approach, thus the control system is guaranteed to be stable within a large range. Sliding Mode Control (SMC) is one of the robust and nonlinear methods which have several advantages such as robustness against matched external disturbances and parameter uncertainties. The employed method is easy to implement in practical applications and moreover, the sliding mode control exhibits the desired dynamic properties during the entire output-tracking process independent of perturbations. Simulation results are presented to demonstrate the effectiveness of the proposed controller in terms of performance, robustness and stability.
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sliding mode observer design for a pwr to estimate the xenon concentration Delayed Neutrons Precursor density based on the two point nuclear reactor model
Progress in Nuclear Energy, 2015Co-Authors: G R Ansarifar, M H Esteki, M ArghandAbstract:One of the important operations in nuclear power plants is load-following in which imbalance of axial power distribution induces xenon oscillations. These oscillations must be maintained within acceptable limits otherwise the nuclear power plant could become unstable. Therefore, bounded xenon oscillation considered to be a constraint for the load-following operation. In other hands, Precursors produce Delayed Neutrons which are most important in control of nuclear reactor, but xenon concentration & Precursor density cannot be measured directly. In this paper, non-linear sliding mode observer which has the robust characteristics facing the parameters uncertainties and disturbances is proposed based on the two point nuclear reactor model to estimate the xenon concentration & Delayed Neutron Precursor density of the Pressurized-Water Nuclear Reactor (PWR) using reactor power measurement. The stability analysis is given by means Lyapunov approach, thus the system is guaranteed to be stable within a large range. The employed method is easy to implement in practical applications. This estimation is done taking into account the effects of reactivity feedback due to temperature and xenon concentration. Simulation results clearly show that the sliding mode observer follows the actual system variables accurately and is satisfactory in the presence of the parameters uncertainties & disturbances.
M Arghand - One of the best experts on this subject based on the ideXlab platform.
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sliding mode observer design for a pwr to estimate the xenon concentration Delayed Neutrons Precursor density based on the two point nuclear reactor model
Progress in Nuclear Energy, 2015Co-Authors: G R Ansarifar, M H Esteki, M ArghandAbstract:One of the important operations in nuclear power plants is load-following in which imbalance of axial power distribution induces xenon oscillations. These oscillations must be maintained within acceptable limits otherwise the nuclear power plant could become unstable. Therefore, bounded xenon oscillation considered to be a constraint for the load-following operation. In other hands, Precursors produce Delayed Neutrons which are most important in control of nuclear reactor, but xenon concentration & Precursor density cannot be measured directly. In this paper, non-linear sliding mode observer which has the robust characteristics facing the parameters uncertainties and disturbances is proposed based on the two point nuclear reactor model to estimate the xenon concentration & Delayed Neutron Precursor density of the Pressurized-Water Nuclear Reactor (PWR) using reactor power measurement. The stability analysis is given by means Lyapunov approach, thus the system is guaranteed to be stable within a large range. The employed method is easy to implement in practical applications. This estimation is done taking into account the effects of reactivity feedback due to temperature and xenon concentration. Simulation results clearly show that the sliding mode observer follows the actual system variables accurately and is satisfactory in the presence of the parameters uncertainties & disturbances.