Abstract
The determination of the subcriticality level constitutes an important issue in the assessment of the accelerator-driven system technology. For this purpose, the interpretation of flux measurements requires a lumped-parameter model employed in an inverse fashion. This papers addresses the drawbacks of point kinetics in performing such a task. In particular, the problem of the generation of integral parameters is considered, in connection with the use of a shape function and of a projection weight tailored to the neutron flux detector. Furthermore, the question of the generation of the effective source is analysed, and some proposals to modify the time dependence of such a function to account for the time delay at the flux detector are presented and discussed.
Highlights
The assessment of the feasibility of subcritical acceleratordriven systems requires the performance of experiments to verify the kinetic response features and the determination of the integral parameters that characterize the physical multiplying structure
The flux interpretation scheme needs unavoidably to account for spectral and spatial effects. It has been shown [6] by numerical simulations that the point model with integral kinetic parameters may be inadequate when local flux signals are used in a point framework to reconstruct the global system reactivity in an inverse fashion, while it may perform rather well for the analysis of the full power evolution, which is, seldom available from the direct experimental information
To simplify the analysis of the results, the shape is adopted as the source-driven neutron distribution within the system, and the attention is focused on the type of point kinetic model that can be constructed by adopting different choices for the weight
Summary
The assessment of the feasibility of subcritical acceleratordriven systems requires the performance of experiments to verify the kinetic response features and the determination of the integral parameters that characterize the physical multiplying structure. The flux interpretation scheme needs unavoidably to account for spectral and spatial effects It has been shown [6] by numerical simulations that the point model with integral kinetic parameters may be inadequate when local flux signals are used in a point framework to reconstruct the global system reactivity in an inverse fashion, while it may perform rather well for the analysis of the full power evolution, which is, seldom available from the direct experimental information. The present paper shall discuss the effectiveness of the weighting to simulate in a point-like manner the evolution of local flux signals, envisaging the possibility of devising tailored point models to interpret experimental measurements and establish the limits of the technique Another aspect that plays an important role in the interpretation procedure for source transients is the suitable timeshape of the neutron source that is assumed in the lumpedparameter model [11].
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