An iterative scheme to include turbulent diffusion in advective-dominated transport of delayed neutron precursors

• Published in: arXiv.org
• Main Authors: Mathis Caprais, Bergeron, André
• Format: Paper
• Language: English
• Published: Ithaca Cornell University Library, arXiv.org 06.11.2024
• Subjects: Diffusivity; Fission products; Fluid dynamics; Fluid flow; High Reynolds number; Mass balance; Method of characteristics; Precursors; Schmidt number; Turbulent diffusion; Turbulent flow; Two dimensional flow

In this study, the Method of Characteristics (MOC) for Delayed Neutron Precursors (DNPs) is used to solve the precursors balance equation with turbulent diffusion. The diffusivity of DNPs, significantly higher than molecular diffusivity, emerges in turbulent flows from the time-averaging of the DNPs mass balance equation. To integrate this effect within the MOC framework, the advection-reaction component of the DNPs balance equation is solved using the MOC, while the diffusive source is computed from the concentration of the previous iteration. The method is validated on a 2D recirculating pipe reactor with high Reynolds number flow, comparing the MOC with diffusion to a standard finite volume (FV) discretization of the fission products balance equation. Additionally, the impact of the diffusivity term on DNP distributions and reactor reactivity is quantified as a function of the turbulent Schmidt number.