S81 asks what MetroVolt's 5.25% neutron budget is worth over a plant lifetime, using only the deposited fluence ledger and applying the same conversion to both contenders. The answer is the strongest single exhibit in the economics case.
MetroVolt: 1.0 dpa per full-power year at the wall → 30 dpa over 30 FPY, inside the 36-dpa qualification — the first wall and vessel last the plant's life, and no breeding blanket exists to replace. D-T comparator at 2.0–2.5 MW/m² by the identical deposited conversion: 20–25 dpa/FPY, replacement every 1.2–1.5 FPY, ~20–25 changeouts over the same life, each a months-long outage.
The blanket cycle alone caps the comparator's availability at 0.71–0.75. On capital-dominated economics that is a +33–42% levelized-cost penalty MetroVolt structurally avoids — derived, not asserted, with the honest flag that the magnet-conductor fluence line sits ~8% above a degradation onset (onset, not failure; margin posture carried in the series).
Fuel choice is usually argued with physics adjectives. S81 converts it to money using our own deposited numbers and mainstream external anchors — the kind of comparison a due-diligence team can re-run in an afternoon. It is the low-neutron thesis, priced.
| MetroVolt lifetime wall dose | 30 dpa ≤ 36-dpa qualification |
| MetroVolt scheduled changeouts | 0 (no breeding blanket) |
| D-T comparator | ~20–25 changeouts · availability 0.71–0.75 |
| Avoided penalty | +33–42% LCOE |
| Method | same deposited dpa conversion, both sides (S81) |