Centrepost Fluence, Damage, and the Consumable-Cartridge Life of a Spherical-Tokamak Breeder

Centrepost fast-neutron fluence, displacement damage, and consumable-cartridge life of a compact spherical-tokamak breeder from coupled OpenMC neutronics. The damage rate and cartridge-replacement interval are booked against a tungsten-carbide shield whose thickness trades directly against machine size and breeding coverage; the mid-current point extends the life. The centrepost is handled as a scheduled-replacement cartridge, not a lifetime component. Physics and engineering only.