The burner's neutron output is computed from stored cross sections across every reaction channel — the D-3He primary, both D-D branches, and the secondary D-T burn — not carried as a hardcoded constant. The provenance of every neutron is traceable.
The solve partitions fusion power by reaction: the neutron-free D-3He channel dominates, with the D-D neutron branch, the D-D proton branch, and a computed secondary D-T burn each contributing. The neutron fraction — 5.44% of fusion power at the deposited design point — is the sum of these, each derived from cross sections and plasma parameters, not a hardcoded literal.
A neutron fraction computed from first principles can be re-derived and challenged; a constant cannot. This is the same discipline the whole programme applies — solve it, don't assume it — applied to the number the plant's shielding, activation, and licensing all depend on.
| Neutron fraction (design point) | 5.44% of fusion power |
| D-3He primary | neutron-free (dominant) |
| Channels summed | D-3He, both D-D, secondary D-T |
| Method | stored cross sections |
| Not | a hardcoded constant |