Integration Readiness
Integration Readiness Levels measure whether subsystems that each work alone will work together as a plant.
The interfaces are where systems fail
Most complex-system failures live at interfaces, not inside boxes. Integration Readiness Levels (IRLs) grade how well two subsystems have been shown to interoperate — from an interface merely identified through interfaces verified and validated under mission conditions. A fusion plant has many such interfaces: plasma to magnets, magnets to cryogenics, blanket to fuel cycle, control system to everything.
Where integration risk concentrates
- The breeder fuel cycle: tritium bred in the blanket must be recovered and returned faster than it decays or is lost — the local-vs-net TBR question is fundamentally an integration question.
- The burner plug: sustaining a 26.49 T plug at the required plasma density couples magnet, heating, and confinement subsystems, and the plug-density requirement remains an open gate.
- Real-time plasma control couples sensing, computation, and actuation on microsecond timescales.
Why the twin exists
A predictive digital twin lets integration be rehearsed before hardware exists, so interface assumptions are tested in simulation first. This raises integration confidence but does not substitute for it: an integrated hardware demonstration is the only thing that closes an IRL at the top of the scale.