Decoupling of neutron and delayed neutron precursor evolutions in source-driven subcritical systems

P. Bosio; T. D. Burns; Jr., P. Ravetto; R. A. Rydin

doi:10.3139/kern-2001-0102

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Article

Decoupling of neutron and delayed neutron precursor evolutions in source-driven subcritical systems

P. Bosio , T. D. Burns , Jr., P. Ravetto and R. A. Rydin

Published/Copyright: March 17, 2022

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From the journal Kerntechnik Volume 66 Issue 5-6

Abstract

The behaviour of neutron and delayed neutron precursors in subcritical systems is considered in time-dependent physical models at different levels of detail. Point kinetics and a simple space model in one-group diffusion theory are assumed at first, in order to be able to construct analytical solutions and to gain a full insight into the problem. More realistic calculations are then performed using a numerical multigroup diffusion code in two-dimensional cylindrical geometry. The results presented clearly show the appearance of a decoupling phenomenon between the evolutions of neutrons and delayed neutron precursors, which is enhanced by the subcriticality level of the multiplying system.

Abstract

Das Verhalten von Neutronen und Mutternukliden verzögerter Neutronen in unterkritischen Systemen wird in zeitabhängigen physikalischen Modellen betrachtet. Zuerst werden punktkinetische Modelle und einfache Raummodelle in der EingruppenDiffusionstheorie angesetzt, um analytische Lösungen zu finden und einen vollständigen Einblick in das Problem zu gewinnen. Danach werden realistischere Berechnungen durchgeführt mit Hilfe eines numerischen Multigruppen-Diffusionscodes in zwei-dimensionaler zylindrischer Geometrie. Die vorgestellten Ergebnisse zeigen klar das Auftreten von Entkoppelungs-Phänomenen zwischen der Entwicklung der Neutronen und der Mutternuklide, die verstärkt werden durch den Subkritikalitätsgrad des multiplizierenden Systems.

References

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Received: 2001-06-26

Published Online: 2022-03-17

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https://doi.org/10.3139/kern-2001-0102