5,566 research outputs found
Interaction between Fluid-Dynamics and Neutronic Phenomena in the Physics of Molten-Salt Systems
No full textThe paper is devoted to the analysis of the importance of fluid-dynamics phenomena in the neutronic simulation of fluid-fuel multiplying nuclear systems. The motion of the delayed neutron precursors has important effects on both steady-state and transient situations. In this paper the role of the motion is studied by assuming that the coupled neutronic-fluid-dynamics model is simplified, introducing different velocity fields as input data for the delayed neutron precursor balance equations. Significant effects are evidenced for steady-state spatial distributions and integral parameters, such as reactivity and effective delayed neutron fractions. Full time-dependent evaluations are also performed to investigate the response in different system configurations to various transient initiator perturbation
Performance of Non-Conventional Factorization Approaches for Neutron Kinetics
No full textThe use of factorization techniques provides a interesting option for the simulation of the time-dependent behavior of nuclear systems with a reduced computational effort. While point kinetics neglects all spatial and spectral effects, quasi-statics and multipoint kinetics allow to produce results with a higher accuracy for transients involving relevant modifications of the neutron distribution. However, in some conditions these methods can not work efficiently. In this paper, we discuss some possible alternative formulations for the factorization process for neutron kinetics, leading to mathematical models of reduced complications that can allow an accurate simulation of transients involving spatial and spectral effects. The performance of these innovative approaches are compared to standard techniques for some test cases, showing the benefits and shortcomings of the method propose
Analytical Solutions to some Neutron Transport Problems in the Spirit of Silvio E. Corno's Teachings
No full text
Analysis of the Role of Fluid-Dynamic Phenomena in the Neutronics of Molten-Salt Systems
No full textDynamics of fluid fuel reactors in the presence of periodic perturbations
No full textThe appearance of perturbations characterized by a periodic time behavior in fluid fuel reactors is connected to the possible precipitation of fissile compounds which are moved within the primary circuit by the fuel motion. In this paper the time-dependent response of a critical fluid fuel system to periodic perturbations is analyzed, solving the full neutronic model and comparing the results with approximate methods, such as point kinetics. A fundamental eigenvalue of the problem is defined, characterizing the trend of divergence of the power. Parametric studies on the reactivity insertion, the fuel velocity and the recirculation time are performed, evidencing the sensitivity of the eigenvalue on typical design parameters. Non-linear calculations in the presence of a negative feedback term are then performed, in order to assess the possibility to control a fluid fuel system when periodic reactivity perturbations are involved
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