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Description
This study computationally evaluates a hybrid nuclear fuel cycle in which partially depleted fuel pebbles from a compact maritime Fluoride-salt-cooled High-temperature Reactor (FHR) are transferred to a larger terrestrial FHR for continued utilization. Neutronic behavior is analyzed using a high-fidelity Monte Carlo framework: the Hyper-Fidelity (HxF) tool models detailed depletion in the maritime reactor, while the Search Equilibrium tool determines the equilibrium steady-state fuel composition in the terrestrial core. Results indicate that the hybrid approach significantly enhances total energy extraction per unit mass of heavy metal compared to independent single-reactor operation. While a conventional once-through cycle achieves an average burnup of 148 MWd/kgHM, transferring pebbles at burnup of 47.5 MWd/kgHM enables a subsequent burnup of 110 MWd/kgHM in the terrestrial core, yielding a total of 157.5 MWd/kgHM, a 6.4% increase. Additionally, performance improves further at lower transfer burnups, with 35 MWd/kgHM transfers achieving total burnups up to 163 MWd/kgHM. These results demonstrate that sequential burning of pebbles in spectrally different reactor environments can outperform the energy extraction limit of single-core operation, providing a potential path toward improved fuel utilization and reduced waste generation for advanced FHR fleets, and potentially other TRISO fueled reactors.