A computationally efficient method for full-core conjugate heat transfer modeling of sodium fast reactors

Abstract

For efficient and accurate temperature predictions of sodium fast reactor structures, a 3-D full-core conjugate heat transfer modeling capability is developed for an advanced system analysis tool, SAM. The hexagon lattice core is modeled with 1-D parallel channels representing the subassembly flow, and 2-D duct walls and inter-assembly gaps. The six sides of the hexagon duct wall and near-wall coolant region are modeled separately to account for different temperatures and heat transfer between coolant flow and each side of the duct wall. The Jacobian Free Newton Krylov (JFNK) solution method is applied to solve the fluid and solid field simultaneously in a fully coupled fashion. The 3-D full-core conjugate heat transfer modeling capability in SAM has been demonstrated by a verification test problem with 7 fuel assemblies in a hexagon lattice layout. Additionally, the SAM simulation results are compared with RANS-based CFD simulations. Very good agreements have been achieved between the results of the two approaches.

A fully-implicit high-order system thermal-hydraulics model for advanced non-LWR safety analyses

“…A more in-depth discussion of the conjugate heat transfer modeling in SAM can be found in Ref. [14].…”

“…A more detailed discussion of the conjugate heat transfer modeling in SAM can be found in Ref. [14]. The inlet of the core channel flow is fixed at constant temperature and flow rate.…”

FY20 SAM Code Developments and Validations for Transient Safety Analysis of Advanced non-LWRs

“…(porous − medium model) (2)(3)(4) and the additional source term in the energy equation, Se, in the fluid energy equation is given as…”

“…It aims to provide fast-running, modest-fidelity, whole-plant transient analyses capabilities, which are essential for fast turnaround design scoping and engineering analyses of advanced reactor concepts. While SAM is being developed as a system-level modeling and simulation tool, advanced modeling techniques being implemented include a reduced-order three-dimensional module [3], pseudo 3-D conjugate heat transfer modeling in reactor core [4], flexible and multi-scale modeling of heat transfer between fluid and structures [5], in addition to the advances in software environments and design, and numerical methods. SAM aims to be a generic system-level safety analysis tool for advanced non-LWRs, including Liquid-Metal-cooled fast Reactors (LMR), Molten Salt Reactors (MSR), Fluoride-salt-cooled High-temperature Reactors (FHR), and High-Temperature Gas-cooled Reactors (HTGR).…”

SAM Developments to Support Transient Safety Analysis of Advanced non-LWRs

“…It aims to provide fast-running, modest-fidelity, whole-plant transient analyses capabilities, which are essential for fast turnaround design scoping and engineering analyses of advanced reactor concepts. While SAM is being developed as a system-level modeling and simulation tool (Hu 2015, Hu 2017b, advanced modeling techniques including a reduced-order three-dimensional module (Hu 2019), pseudo 3-D conjugate heat transfer modeling in reactor core (Hu and Yu 2016), in additional to the advances in software environments and design, numerical methods. SAM aims to be a generic system-level safety analysis tool for advanced non-LWRs, including Liquid-Metal-cooled fast Reactors (LMR), Molten Salt Reactors (MSR) or Fluoride-salt-cooled High-temperature reactor (FHR), and high-temperature gas-cooled reactor (HTGR).…”