Date of Award

Fall 2025

Document Type

Open Access Thesis

Department

Nuclear Engineering

First Advisor

Travis Knight

Abstract

High-fidelity computational fluid dynamics (CFD) programs can resolve complex thermohydraulic behavior in high-temperature gas-cooled reactors (HTGRs), but this comes with prohibitive computational cost, especially for accident transient analyses. This work develops and validates reduced-order, 3D/1D conjugate heat transfer simulations of the University of South Carolina’s Transportable Helium-cooled One-megawatt Reactor (THOR) using Argonne National Laboratory’s Systems Analysis Module, which is built upon Idaho National Laboratory’s MOOSE framework. The methodologies discussed herein couple 3D solid conduction to 1D fluid convection using the MOOSE MultiApp system, achieving modest fidelity simulation of HTGR thermohydraulic behaviors, capable of accurate solutions with significantly reduced computational resource requirements. The methodologies were benchmarked in steady-state against both high-fidelity STAR-CCM+ simulations and experimental data from the L-STAR facility in Karlsruhe, Germany. Transient data from the L-STAR facility was also utilized to conduct a transient benchmark. The ROM methodologies discussed herein are shown to be flexible and provide accurate solutions with dramatic reductions in both runtime and computational complexity when compared to modern CFD approaches.

Rights

© 2025, Matthew R. Phipps

Available for download on Thursday, December 31, 2026

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