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Question
What is the biggest technical risk in the Kronos design?
The confinement requirement — H98 = 1.84 — is the single largest bet, and its nonlinear-gyrokinetic verification is the outstanding item, tested first at the G1 gate.
Kronos names its biggest risk rather than hiding it: the confinement bet. Its honest open-item register and the Falsifiable Seven exist precisely to make these risks checkable.
Questions & answers
What is the biggest risk in the design?
The confinement requirement. The design needs a confinement multiplier of H98 = 1.84, which assumes negative triangularity suppresses turbulence as expected. That is supported by reduced-order models and the DIII-D NT database, but the load-bearing nonlinear gyrokinetic (CGYRO) verification is not yet complete.
What are the other main open items?
The hot-ion posture (a full analysis found it isn't sustainable at the ceiling, so the near-thermal case is the baseline); divertor detachment at f_rad ≈ 0.998; energetic-particle (TAE) transport; and runaway-electron mitigation. Kronos publishes all of them in a ranked open-item register.
How does Kronos manage these risks?
By pre-registering them as falsifiable predictions and testing the load-bearing ones at the G1 confinement testbed before committing further — and by planning to the conservative baseline, treating the upside as something to be earned.
Honest gapThe nonlinear gyrokinetic (CGYRO) confirmation of H98 = 1.84 is the outstanding load-bearing verification; the hot-ion ceiling is not sustainable per S61, so the near-thermal baseline governs.