Center-Post Lifetime — the ~0.01 fpy Note
The center-post has a short design life, on the order of 0.01 full-power-years before replacement — an honest constraint the machine plans around.
A short life, stated plainly
The center-post's design life is short. As a working note the breeder carries an order of ~0.01 full-power-years (fpy) of accumulated operation before the center-post needs replacement. This is not a failure of the design; it is a consequence of putting the most stressed, most irradiated conductor in the least-shielded volume of a deliberately compact machine.
Why so short
The inboard center stack has little room for shielding, so the center-post absorbs a high neutron dose per unit of operation. Fast-neutron damage degrades conductor and insulation properties quickly, and the mechanical environment is severe. Rather than enlarge the machine to protect the center-post — which would defeat the compact rationale — the design accepts frequent replacement.
- ~0.01 fpy is a design working figure, not a target to hide.
- Short life follows directly from minimal inboard shielding.
- Enlarging the machine to extend life defeats the compact design.
- Replacement is engineered in from the start.
What it demands of the rest of the machine
A short center-post life is only acceptable if replacement is fast and reliable. This drives the remote-handling design, the way the center stack is segmented, and the maintenance schedule. The ~0.01 fpy note is stated openly because it is a genuine constraint that shapes the whole machine, and hiding it would misrepresent the design.
This page documents a design and simulation study, not a built machine. Construction begins Q2 2027; first-of-a-kind first tritium is targeted near 2030. Figures are computed, reproducible targets, not measurements.