Tritium breeding lifetime assessment of a ceramic-based blanket in a fusion tokamak device

Achieving tritium self-sufficiency is a critical requirement for the viability of future fusion power plants. Here, a comprehensive assessment of the operational lifetimes of ceramic breeder materials under neutron irradiation within a tokamak environment is resented, focusing on the evolution of the tritium breeding ratio (TBR) over reactor-relevant timescales. This is defined here as the operational timeframe at which the TBR is maintained above a critical threshold of ≈1.10. Using the depletion capabilities within the OpenMC neutronics code, both conventional ceramic breeders (Li2TiO3, Li4SiO4, and advanced ceramic breeder – ACB) and emerging hybrid breeder-multiplier ceramics (Li8PbO6, Li2Be2O3) are assessed for operational lifetime strategies. Initial optimisation identifies breeder-to-multiplier volumetric ratios that maximise TBR at time zero, followed by time-dependent simulations to quantify TBR degradation due to lithium depletion during service. It is shown that while higher initial multiplier fractions enhance TBR, they also accelerate lithium depletion, reducing blanket lifetime. Conversely, hybrid ceramics with intrinsic neutron multiplication show reduced sensitivity to additional multipliers. A novel layer-wise optimisation approach, varying breeder and multiplier distributions radially and poloidally, is shown to extend blanket lifetimes and maintain TBR above the critical threshold for longer periods demonstrating lifetime limitations may be elsewhere within the breeder blanket. Verification against FISPACT-II confirms the accuracy of the OpenMC depletion methodology utilised. The results highlight the importance of spatially optimised material distributions and lithium inventory management in maximising breeder blanket longevity. This work provides robust framework for the design of next-generation solid breeder blankets, offering practical strategies to minimise replacement frequency and support sustainable fusion energy.