TY - GEN
T1 - High-Fidelity CFD Simulation of Mixed Convection in a Pebble Bed Test Reactor Core
AU - Yuan, Haomin
AU - Shaver, Dillon
AU - Nguyen, Tri
AU - Merzari, Elia
AU - Reger, David
AU - Yau, Ka Yen
AU - Busco, Giacomo
AU - Salpeter, Nate
AU - Brian Jackson, R.
N1 - Publisher Copyright:
© 2023 Proceedings of the 20th International Topical Meeting on Nuclear Reactor Thermal Hydraulics, NURETH 2023. All rights reserved.
PY - 2023
Y1 - 2023
N2 - The Hermes low-power (35 MWth) reactor will be built and operated by Kairos Power LLC to demonstrate their Fluoride cooled high-temperature reactor (KP-FHR) technology. In the KP-FHR, the reactor core is composed of randomly packed pebbles with TRISO fuel particles inside. FLiBe flows upward through the pebble bed acting as a coolant to remove heat. Under low to moderate flow conditions, buoyancy plays a critical role. In this study, we simulated a pebble bed core with 34374 pebbles randomly packed, similar to the Hermes reactor's size. The core radius is 14 times of the pebble-diameter, while the core height is 45 times. A Large-Eddy Simulation (LES) of the flow inside the pebble bed has been performed at Re = 160 (based on inlet velocity and pebble diameter) and pebble power at 1680 W per pebble. The Spectral Element CFD code NekRS with GPU acceleration was used for this study. The low-Mach number approximation has been applied to address property changes in the FLiBe and account for buoyancy. A pure hexahedral mesh with 60 million elements was generated by the Voronoi-cell method. The Grashof number in the simulation is on the order from 106 to 107. The local Reynolds number is on the order of 103, resulting in a Richardson number between 1 and 10 across the domain. Thus, the flow is in the mixed convection regime. The Nusselt number across the domain is obtained and compared with empirical correlations.
AB - The Hermes low-power (35 MWth) reactor will be built and operated by Kairos Power LLC to demonstrate their Fluoride cooled high-temperature reactor (KP-FHR) technology. In the KP-FHR, the reactor core is composed of randomly packed pebbles with TRISO fuel particles inside. FLiBe flows upward through the pebble bed acting as a coolant to remove heat. Under low to moderate flow conditions, buoyancy plays a critical role. In this study, we simulated a pebble bed core with 34374 pebbles randomly packed, similar to the Hermes reactor's size. The core radius is 14 times of the pebble-diameter, while the core height is 45 times. A Large-Eddy Simulation (LES) of the flow inside the pebble bed has been performed at Re = 160 (based on inlet velocity and pebble diameter) and pebble power at 1680 W per pebble. The Spectral Element CFD code NekRS with GPU acceleration was used for this study. The low-Mach number approximation has been applied to address property changes in the FLiBe and account for buoyancy. A pure hexahedral mesh with 60 million elements was generated by the Voronoi-cell method. The Grashof number in the simulation is on the order from 106 to 107. The local Reynolds number is on the order of 103, resulting in a Richardson number between 1 and 10 across the domain. Thus, the flow is in the mixed convection regime. The Nusselt number across the domain is obtained and compared with empirical correlations.
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U2 - 10.13182/NURETH20-40499
DO - 10.13182/NURETH20-40499
M3 - Conference contribution
AN - SCOPUS:85202919297
T3 - Proceedings of the 20th International Topical Meeting on Nuclear Reactor Thermal Hydraulics, NURETH 2023
SP - 645
EP - 658
BT - Proceedings of the 20th International Topical Meeting on Nuclear Reactor Thermal Hydraulics, NURETH 2023
PB - American Nuclear Society
T2 - 20th International Topical Meeting on Nuclear Reactor Thermal Hydraulics, NURETH 2023
Y2 - 20 August 2023 through 25 August 2023
ER -