MetroVolt's first wall sees 0.074–0.089 MW/m² of neutron load at the Mode-D operating ledger — roughly an order of magnitude below a D-T power plant. Over 30 full-power years that integrates to ~22 dpa, inside the vessel alloy's ~36-dpa qualification target: the wall is designed to die of old age with the plant.
Wall dose is fuel chemistry made visible: at the operating 7.70% neutronicity and 1.22 GW, the deposited fluence ledger (KX-10D/S81) gives 0.74 dpa per full-power year at the MetroVolt wall. The vessel class is a CrMoNbV high-entropy alloy carried against an explicit ≈36-dpa capability qualification — stated as a target for the alloy programme, not a solved problem.
The same ledger, applied with the same conversion to a 2.0–2.5 MW/m² D-T comparator, yields 20–25 dpa/FPY — blanket and wall replacement every 1.2–1.5 full-power years, ~20–25 changeouts over a plant life. MetroVolt schedules zero.
Availability is the quiet variable that decides fusion economics. A blanket-changeout cycle caps a D-T plant near 0.71–0.75 availability; MetroVolt's wall imposes no such cycle, preserving the N+1-redundant plant availability >0.9 computed in the series. That difference alone is worth +33–42% on levelized cost — derived, deposited, and ours to keep.
| First-wall load | 0.074–0.089 MW/m² (Mode D) |
| Dose rate | 0.74 dpa / full-power year (deposited) |
| Lifetime dose | ≈22 dpa over 30 FPY ≤ ~36-dpa qualification |
| Scheduled wall/blanket changeouts | 0 (vs ~20–25 for D-T comparator) |
| Availability protected | >0.9 (N+1 basis) |