Tritium Breeding Cycle Twin
A breeder twin tracks the tritium produced, bred, extracted, and consumed, closing the fuel cycle accounting in real time.
Accounting for the fuel
A deuterium-tritium plant must breed at least as much tritium as it burns, because tritium is scarce and decays. The breeding blanket surrounds the plasma with lithium, which captures fusion neutrons and produces tritium. A twin of the breeding cycle tracks the full inventory, how much is produced, bred, extracted, stored, and consumed, and forecasts whether the cycle stays closed.
The tritium breeding ratio
The key figure of merit is the tritium breeding ratio, the tritium bred per tritium consumed. It must exceed one, with margin, for a plant to be self-sufficient. The Hyperion breeder is designed to a tritium breeding ratio of 1.8, a deliberate margin above unity. A twin does not assume this number; it tracks the effective, as-operated breeding ratio from neutronics and extraction data, and flags any shortfall against the design intent.
What the twin couples
- Neutron production from the plasma, tied to the reconstructed reaction rate
- Neutron transport and capture in the blanket, producing tritium
- Extraction efficiency and holdup of tritium in materials
- Storage inventory and the tritium fed back to the plasma
Why estimation is essential
Tritium inventory is notoriously hard to measure directly, since tritium hides in materials and moves through many stages. The twin reconstructs the inventory from indirect measurements and neutronics, with uncertainty, providing an accounting that direct instruments cannot. This matters for both operations and the strict accountancy that tritium handling requires.
In the Hyperion breeder
The Hyperion breeder is a deuterium-tritium spherical tokamak whose purpose includes breeding tritium. Its twin couples neutronics, blanket chemistry, and inventory tracking to monitor the cycle against the design breeding ratio of 1.8. All of this is developed today on validated neutronics and design models; the effective breeding ratio can only be measured once the machine operates, with first tritium targeted near 2030, and no self-sufficiency claim is made before then. See neutronics twin.