fuelcycle

A modular and flexible package to model nuclear fusion fuel cycle based on the residence time method.

The model is based on 4 main objects:

• Component: recursive container for states and component properties, with the possibility of defining children components.
• State: species properties defined per component, exposed as component.T.
• CompiledModel: flat CVODE (scikit-sundae) runtime arrays, callbacks, and sparse Jacobian pattern.
• SolveResult: solver output.

Minimal example

import fuelcycle_cvode as fc

 # define a base component, describing the entire model
system = fc.Component("system")

# add components
storage = system.add_component("storage")
fueling = system.add_component("fueling")

# define states
storage.add_species("T", N=1.0e22, tau=100.0)
fueling.add_species("T", N=0.0, tau=20.0)

# connect states/components and visualize the network
system.connect(storage, fueling, species="T", fraction=0.2, name="storage_to_fueling")
print(system.connection_map_text(include_equations=True))

# solve
result = system.solve((0.0, 100.0), backend="auto", t_eval=[0.0, 10.0, 100.0])
print(result.final(fueling.T))

References:

• Abdou, M., Riva, M., Ying, A., Day, C., Loarte, A., Baylor, L.R., Humrickhouse, P., Fuerst, T.F., Cho, S., 2021. Physics and technology considerations for the deuterium–tritium fuel cycle and conditions for tritium fuel self sufficiency. Nucl. Fusion 61, 013001. https://doi.org/10.1088/1741-4326/abbf35

• Meschini, S., Ferry, S.E., Delaporte-Mathurin, R., Whyte, D.G., 2023. Modeling and analysis of the tritium fuel cycle for ARC- and STEP-class D-T fusion power plants. Nucl. Fusion 63, 126005. https://doi.org/10.1088/1741-4326/acf3fc

• Meschini, S., Delaporte-Mathurin, R., Tynan, G.R., Ferry, S.E., 2025. Impact of trapping on tritium self-sufficiency and tritium inventories in fusion power plant fuel cycles. Nucl. Fusion 65, 036010. https://doi.org/10.1088/1741-4326/adacfa

• Hattab, F., Igitkhanov, Y., Narcisi, V., Santucci, A., Giannetti, F., Centomani, G.V., Staniec, P.A., Kembleton, R., Giegerich, T., 2026. Analysis and modelling of Inner Fuel Cycle performance using exhaust bypass and Direct Internal Recycling. Fusion Engineering and Design 225, 115668. https://doi.org/10.1016/j.fusengdes.2026.115668