Tritium Self-Sufficiency Is Not Yet Proven

A D-T machine must breed more tritium than it consumes; for the breeder this closure is a design target the record explicitly labels as unproven.

The closure condition

Tritium does not exist in useful natural quantity and decays with a 12.3-year half-life. A D-T fusion machine must therefore breed its own. Self-sufficiency is the condition that tritium bred, over a period, exceeds tritium burned plus tritium lost to decay and to processing. The breeder (Hyperion) is designed toward this closure; it has not demonstrated it.

# Tritium balance (schematic closure condition)
# bred >= burned + decay_losses + process_losses + startup_holdup
# net_TBR = bred / burned  must exceed 1 with margin for the losses.
# Status: target net TBR toward 1.8; local-vs-net gap OPEN;
#         closure is a DESIGN TARGET, not a demonstrated result.

Why it is honest to flag this

Every D-T fusion concept faces this problem, and a program that does not name it is hiding its hardest fuel-cycle question. The breeder record states plainly that self-sufficiency is unproven, that it depends on resolving the local-vs-net TBR, and that a startup tritium inventory and fuel-cycle losses must be counted in the balance, not assumed away.

What would prove it

Proof requires a validated net-TBR analysis at realistic geometry followed by FOAK operation measuring the actual tritium accounting. Until both exist, the correct statement is that the machine is designed to be self-sufficient, and whether it is remains to be shown.

Startup is a distinct part of the problem that is easy to overlook. A breeder cannot breed before it operates, so a first inventory of tritium must come from elsewhere to begin, and the fuel cycle must then overtake burn and losses to become self-supporting. The record counts this startup holdup in the balance rather than presenting self-sufficiency as a property the machine possesses from the first shot.

This page describes a design-and-simulation study, not a built machine. Construction of the breeder (Hyperion) begins Q2 2027; first-of-a-kind first tritium is targeted near 2030. No hardware net-gain claim is made before FOAK.