The burner's fuel cycle is tritium-lean by construction: it produces tritium only as a transient D-D by-product, burns much of it immediately, and lets the rest decay toward helium-3. Its standing tritium inventory is a trace, enforced by the cycle's own mass balance.
Unlike a D-T plant, the burner never stores tritium as fuel. The D-D breeding branch makes a small amount, about 17% of which burns in secondary reactions; the remainder decays to helium-3 — the fuel the plant actually wants. The mass-balance ledger holds the standing inventory to a trace quantity.
A fuel cycle that keeps tritium a trace species is a fuel cycle with a small radiological source term. Tritium-lean is therefore both a licensing posture and a fuel-cycle fact, and it falls directly out of choosing D-3He over D-T.
| Burner tritium | transient D-D by-product |
| Burned immediately | ~17% |
| Remainder | decays to helium-3 |
| Standing inventory | trace (mass-balance enforced) |
| Consequence | small radiological source term |