Redundancy Topologies

N, N+1, 2N, and distributed-redundant topologies trade spare capacity for uptime; the choice sets how the burner fleet, storage, and grid combine to reach Tier III.

Choosing how much spare to carry

Redundancy comes in standard shapes. N carries exactly the load with no spare. N+1 adds one spare unit. 2N duplicates the entire supply into two independent systems. Distributed-redundant (sometimes N+1 spread across many modules) shares spare capacity across the whole plant. Each buys more uptime with more idle capacity.

For a MetroVolt campus the topology decides how the members combine. An N+1 burner fleet plus an independent grid and battery may reach Tier III with modest spare; a 2N approach carries more idle capacity but tolerates the loss of an entire supply path. Given the availability gate, most designs will lean toward richer redundancy than a conventional plant, because the base source is less reliable to start with.

Topology also interacts with the burner's other gates. More units means more helium-3 demand, so the fuel-supply gate pushes back on carrying large idle fusion capacity purely for redundancy — one reason the grid and storage layers, which need no He-3, are attractive redundancy members.

The engineering task is to pick the topology whose combined availability clears Tier III while minimizing idle fusion capacity, leaning on the fuel-free grid and battery layers to supply much of the redundancy.

• N, N+1, 2N, distributed-redundant trade spare for uptime
• Weaker base source favors richer redundancy
• More burner units means more He-3 demand
• Grid and battery add redundancy without fuel demand