MetroVolt's ratified Mode-D point operates at normalized pressure βN = 4.96 — at the computed wall-stabilised limit of 5.0 (the binding constraint of the whole design, +1% margin). The deposited MHD programme states what that requires: rotation plus kinetic resistive-wall-mode control, carried as baseline physics, not upside.
Ideal-MHD analyses (MISHKA/MARS-K-class decks, S22/S25) adjudicate the with-wall limit at βN ≈ 5.0, conditioned on plasma rotation and kinetic resistive-wall-mode stabilization — requirements stated, not waved away. The robustness envelope (S79) prices the prize: at βN = 5.0 the same frozen geometry delivered +24% fusion power in the as-studied hot-ion-era pricing (2,409 → 2,999 MW) at unchanged confinement quality, with the density limit becoming the next boundary — an envelope the Mode-D re-basis then adopted as the operating regime.
The Mode-C era ran at βN 4.33 with the wall-stabilised regime held in reserve; the corrected-physics re-optimization (24 July 2026) moved the operating point to 4.96 against the 5.0 limit, so what was an upgrade path is now baseline-critical — stated plainly and carried in the gap register.
The honest statement is the inverted one: after the corrected physics, MetroVolt needs the wall-stabilised regime to operate, and says so. The MARS-K decks that adjudicate it are public, the rotation requirement is explicit, and the graceful-retreat path (S80 operating window, −37% density room) is priced.
| Operating βN | 4.96 (Mode D) vs computed limit 5.0 — binding, +1% |
| No-wall limit | βN 3.20 (S21) |
| Mode-C-era point | 4.33 (labeled history) |
| Conditions | rotation + kinetic RWM stabilization — baseline-critical |
| Next boundary after β | Greenwald fraction 1.30 |