Decommissioning Waste

At end of life the machine itself becomes the waste inventory — activated structure that, after decay, is largely recyclable or clearable.

When a fusion plant reaches end of life, the waste is the machine: the activated first wall, blanket, shield, vessel, and the innermost building structure. Because there is no spent fuel to remove and no actinides to isolate, decommissioning is fundamentally a materials-management exercise — let the activation decay, then recycle or clear as much as possible and dispose of the remainder as low-level waste.

The decommissioning sequence

• Defuel and detritiate: remove the small tritium inventory and outgas tritiated components.
• Decay storage: allow short- and medium-lived activation to decay, in place or in interim storage.
• Dismantle and sort: separate by activation level, guided by material records.
• Recycle, clear, or dispose: recover metals where possible; dispose of the residual as LLW/ILW.

The contrast with fission decommissioning is that there is no separate, long-lived spent-fuel problem sitting outside the reactor building. The whole inventory decays on a timescale set by activation, not by actinides, so the endpoint is reached in decades rather than being deferred to a geological repository.

Planning decommissioning during design, not after operation, is what keeps it bounded: material records, modular construction, and clearance-oriented material choices are all decided up front. The result is an end-of-life plan whose timescale and volume are known before the machine ever operates.

The honest part is that decommissioning still requires decay time, remote dismantling of the highest-flux components, and a real, if modest, disposal stream. It is a managed, bounded operation. These are design-and-simulation expectations for machines whose service lives are still ahead.