One-dimensional gas-fueled nuclear reactor with thermal feedback

Fuente: arXiv
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Auteurs principaux: Caprais, Mathis, François-Elie, Kacim, Tomatis, Daniele
Format: Preprint
Publié: 2024
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author Caprais, Mathis
François-Elie, Kacim
Tomatis, Daniele
author_facet Caprais, Mathis
François-Elie, Kacim
Tomatis, Daniele
contents This study explores a simplified one-dimensional subchannel of a graphite-moderated nuclear reactor operating with a gaseous core in steady-state conditions, reproducing a neutronic-thermal-fluid-dynamics coupled problem with thermal feedback. The fuel gas, consisting of a homogeneous mixture of uranium hexfluoride (\ce{UF_6}) and helium, is assumed to be ideal, with simplifications made to its thermodynamic state. Due to the high thermal expansion of the fuel, a possible interesting strong coupling is anticipated. The discrete ordinates' method is used to compute the one group scalar flux, the effective multiplication factor and the power released by the core. Six groups of Delayed Neutron Precursors (DNPs) are used to take into account the fuel motion drift. Compressible Euler equations are solved with a monolithic approach and the two-physics problem is treated with Picard iterations. As expected, the effective multiplication factor of a subchannel is shown to increase with the inlet pressure. The critical pressure, representing the threshold at which the system achieves criticality, changes as the fuel mixture changes. High thermal feedback coefficients are observed due to the high thermal expansion of the fuel. The amount of helium in the mixture greatly affects the temperature at core outlet in critical configurations. This study shows that a gaseous fuel reactor can be brought to criticality varying the inlet pressure. The thermal feedback is strong and should be taken into account in the design of the system.
format Preprint
id arxiv_https___arxiv_org_abs_2407_12530
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle One-dimensional gas-fueled nuclear reactor with thermal feedback
Caprais, Mathis
François-Elie, Kacim
Tomatis, Daniele
Computational Physics
This study explores a simplified one-dimensional subchannel of a graphite-moderated nuclear reactor operating with a gaseous core in steady-state conditions, reproducing a neutronic-thermal-fluid-dynamics coupled problem with thermal feedback. The fuel gas, consisting of a homogeneous mixture of uranium hexfluoride (\ce{UF_6}) and helium, is assumed to be ideal, with simplifications made to its thermodynamic state. Due to the high thermal expansion of the fuel, a possible interesting strong coupling is anticipated. The discrete ordinates' method is used to compute the one group scalar flux, the effective multiplication factor and the power released by the core. Six groups of Delayed Neutron Precursors (DNPs) are used to take into account the fuel motion drift. Compressible Euler equations are solved with a monolithic approach and the two-physics problem is treated with Picard iterations. As expected, the effective multiplication factor of a subchannel is shown to increase with the inlet pressure. The critical pressure, representing the threshold at which the system achieves criticality, changes as the fuel mixture changes. High thermal feedback coefficients are observed due to the high thermal expansion of the fuel. The amount of helium in the mixture greatly affects the temperature at core outlet in critical configurations. This study shows that a gaseous fuel reactor can be brought to criticality varying the inlet pressure. The thermal feedback is strong and should be taken into account in the design of the system.
title One-dimensional gas-fueled nuclear reactor with thermal feedback
topic Computational Physics
url https://arxiv.org/abs/2407.12530