Deep Dive: Disruptions & Safety

How Kronos reduces disruption likelihood, budgets a 10 GJ event, and relies on fusion's passive safety — with runaway mitigation stated as an open item.

Design case

~10 GJ at 42.5 MA

Reduced by

ELM-free edge, vertical margin 2.02, RWM feedback

Passive safety

No chain reaction; plasma fails safe

Open item

Runaway-electron mitigation

Safety in a tokamak is dominated by disruptions — the sudden loss of confinement — and by fusion's inherent passive safety. Kronos addresses both.

Reducing disruptions. The negative-triangularity edge is ELM-free, removing one whole class of edge events; the vertical-control margin is 2.02 (S69); and a resistive-wall-mode feedback system holds the plasma stable at high beta. Fewer triggers, stronger control.

Budgeting the loads. When a disruption does occur, the design accounts for an event of order 10 GJ at 42.5 MA — thermal, electromagnetic, and mechanical loads all budgeted. The honest open item is runaway-electron mitigation at that current.

Passive safety. Fundamentally, fusion cannot melt down or run away — the plasma holds seconds of fuel and fails safe on any loss of input. The engineered hazards (magnet energy, tritium, activation) are controlled, not accident-scale.