Supply and Demand Boundary Conditions

Whether a tritium source is a net supplier depends on breeding surplus, internal burn, processing losses, and the external demand it is asked to serve.

The balance that must close

A tritium account balances sources against sinks. Sources are breeding and any imported make-up. Sinks are internal burn, decay at ~5.5%/yr, processing losses, and external withdrawals. A device is a net supplier only when breeding exceeds every sink combined, with headroom to spare.

Why headroom matters

A design that is just barely self-sufficient has no cushion: a small increase in losses or a small shortfall in breeding tips it into deficit, and decay does the rest. This is why the breeder studies TBR as high as 1.8 — surplus above self-sufficiency is what turns a fuel-neutral machine into a dependable external source.

• Sinks include decay, which never pauses.
• Surplus above self-sufficiency is the exportable quantity.
• Thin surpluses are fragile to modest losses.

Why thin balances are fragile

A balance that closes only barely is fragile in a specific way: small, realistic errors can flip its sign. A modest increase in processing loss, a slight shortfall in breeding, or a temporary rise in internal burn can each push a just-sufficient design into deficit, and decay then compounds the shortfall. Designing for headroom above self-sufficiency buys tolerance against exactly these ordinary variations. This is the practical reason the breeder study reaches toward higher breeding values rather than aiming to close the balance by the smallest possible amount.

These boundary conditions are evaluated in simulation for the breeder. The resulting surplus is a computed design target; the actual balance is a measurement that FOAK operation is intended to provide.